Stem Cell Transplantation for Pulpal Regeneration: A Systematic Review.

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Tissue Engineering Part B: Reviews Stem/progenitor cell transplantation for pulpal regeneration: A systematic review and meta-analysis of animal studies (doi: 10.1089/ten.TEB.2014.0675) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

1

Stem Cell Transplantation for Pulpal Regeneration: A Systematic Review Karim M. Fawzy El-Sayed1,2, Kimberley Jakusz3, Arne Jochens4, Christof Dörfer1, Falk Schwendicke3 1

Clinic for Conservative Dentistry and Periodontology, Christian-Albrechts-Universität Kiel,

Germany 2

Oral Medicine and Periodontology Department, Faculty of Oral and Dental Medicine, Cairo

University, Egypt 3

Department of Operative and Preventive Dentistry, Charité – Universitätsmedizin Berlin,

Germany 4

Institute for Medical Informatics and Statistics, Christian-Albrechts-Universität Kiel,

Germany

Corresponding author: Dr. Karim M. Fawzy El-Sayed, MSc, PhD, MFDS-RCSEd Clinic for Conservative Dentistry and Periodontology School of Dental Medicine Christian Albrechts-Universität zu Kiel Arnold-Heller-Str. 3, Haus 26, 24105 Kiel, Germany Phone:

(+49) 431 597 2817

Fax:

(+49) 431 597 4108

Email: [email protected]

Number of words in abstract: 271


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2

Total words (abstract – acknowledgements): 2573

Total tables and figures: 5

Supplemental tables and figures: 2

Number of references: 30

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3 Abstract For

treating

pulpal

pathological

conditions,

pulpal

regeneration

via

transplanted

stem/progenitor cells might be an alternative to conventional root canal treatment. A number of animal studies demonstrated beneficial effects of stem/progenitor cell transplantation for pulp-dentin complex regeneration, i.e. pulpal tissue, neural, vascular and dentinal regeneration. We systematically reviewed animal studies investigating stem/progenitor cell mediated pulp-dentin complex regeneration. Studies quantitatively comparing pulp-dentin complex

regeneration

after

transplantation

of

stem/progenitor

cells

versus

no-

stem/progenitor cell transplantation controls in intraoral in vivo teeth animal models were analysed. The following outcomes were investigated: regenerated pulp area per root canal total area, capillaries per total surface, regenerated dentinal area per total defect area and nerves per total surface. PubMed and EMBASE were screened for studies published until July 2014. Cross-referencing and hand search were used to identify further articles. Standardised mean differences (SMD) and 95% Confidence Intervals (95%CI) were calculated using random-effects meta-analysis. To assess possible bias, SYRCLE’s risk of bias tool for animal studies was used. From 1364 screened articles, five studies (representing 64 animals) were included in the quantitative analysis. Risk of bias of all studies was high. Stem/progenitor cell transplanted pulps showed significantly larger regenerated pulp area per root canal total area (SMD [95%CI]: 2.28 [0.35-4.21]) and regenerated dentin area per root canal total area (SMD: 6.91 [5.39-8.43]) compared to nostem/progenitor cells transplantation controls. Only one study reported on capillaries per or nerves per total surface, and found both significantly increased in stem/progenitor cell transplanted pulps compared to controls. Stem/progenitor cell transplantation seems to enhance pulp-dentin complex regeneration in animal models. Due to limited data quantity and quality, current evidence levels are insufficient for further conclusions. Keywords: Stem cells, Pulp, regeneration, systematic review, meta-analysis

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4 Introduction Conventional

endodontic

treatment

focuses on

the

three-dimensional

mechanical

preparation, disinfection and subsequent obturation of the root canal space using inert biocompatible materials without any regeneration of pulpal tissues. Given the impact of pulpal loss of vitality on the prognosis of teeth (1), repair and/or regeneration of the pulpdentin complex remain a major goal of dental endodontics (2). Recent advances in tissue engineering have paved the way for biologically reparative/regenerative pulpal therapy (3). Stem/progenitor cell transplantation for tissue regeneration has been applied with promising results in various medical fields, including the treatment of cardiovascular diseases (4) and for periodontal regeneration (5). Generally, such treatments aim at modulating the local microenvironment to be more inductive for endogenous cells (6, 7), to enhance the migration, proliferation, and commitment of endogenous and/or exogenous stem/progenitor cells to suitably committed cells, and to favor the biosynthesis of extracellular matrix components for tissue regeneration (8). The locally delivered stem/progenitor cells thereby exert their effects at multiple levels, including neovascularization (9), immunomodulation (10) and tissue regeneration (5), relying on their multipotency (11) and sensitivity to local paracrine activity (4). The pulp-dentin complex originates embryonically from the neural crest-ectomesenchyme and constitutes physiologically and functionally a single unit, providing vital functions for tooth homeostasis (12). The dental pulp is a richly vascularized and innervated connective tissue, comprised of heterogeneous cell populations, among which stem/progenitor cells are anticipated to constantly replenish odontoblasts to form secondary and tertiary/reparative dentin throughout adult life (13). In reparative/regenerative approaches, mesenchymal stem/progenitor cells transplantation into endodontically treated root canals was therefore attempted to regenerate the damaged dental pulp–dentin complex. So far, most of this research has been performed in animal experiments due to remaining doubts about the safety and efficacy of such treatments as well as ethical constraints.

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5 However, to translate experimental outcomes from animal models to human clinical trials, both the design and the results of these animal studies need to be critically and systematically appraised to identify gaps in their validity and to assess the reported effects of the regenerative endodontic therapy. The goal of the present study was to provide such systematic and critical review of the available data from animal studies on stem/progenitor cells transplantation for pulp-dentine complex regeneration. Methods Reporting of this review follows guidelines outlined by the SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) (14). Searching We systematically screened electronic databases (Medline via PubMed, EMBASE) for papers published between November 1971 and July 2014, and additionally performed hand searches in relevant journals including Journal of Dental Research, Journal of Endodontics, Stem Cells and Tissue Engineering. Unpublished (grey) literature was searched via opengrey.eu. Our search strategy used a two-pronged approach, combining keywords for stem cells with keywords for pulp regeneration (Tab. S1). No language restriction was applied. Screening of titles and abstracts was independently performed twice by two reviewers (KFE, KJ). A third reviewer (CD) was consulted in case of disagreement to reach consensus regarding potential eligibility. Identified papers were assessed in full-text and eligibility independently decided by two reviewers (KFE, KJ). In case of disagreement, consensus was obtained by consulting a third reviewer (CD). Bibliographies of full-texts were used for cross-referencing. Selection The following inclusion criteria were applied:

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6 (I)

Study design: We included animal studies transplanting stem/progenitor cells in intraoral experimental pulpal regeneration models, mimicking the clinical oral condition in humans. Studies needed to quantitatively report on one or more of the defined outcomes (see below).

(II)

Intervention: stem/progenitor cells transplantation without further treatment with growth/differentiation factors etc.

(III)

Control: no stem/progenitor cells transplantation. Controls were groups without active treatments, i.e. only scaffold/carrier or no treatment (empty pulpal cavum) groups.

(IV)

Outcomes: We assessed one primary and three secondary outcomes: Pulpal regeneration (regenerated pulp area per amputated root canal total areas); dentinal regeneration (regenerated dentinal area per total defect area); vascular regeneration (capillaries per amputated root canal total area); and neuronal regeneration (nerves per amputated root canal total area).

Quality assessment For risk of bias assessment, guidelines outlined by SYRCLE (14) were used. The following domains were evaluated: 1. Selection bias: Method of sequence generation was assessed and results of randomisation controlled by evaluating baseline characteristics of test and control groups (age, sex, weight, rearing conditions). Allocation was evaluated with regards to allocation sequence (sequence generation before lesion induction or not) and adequate concealment. 2. Performance bias: Random housing (i.e. comparable housing of test and control animals) was assessed, since housing conditions might influence study outcomes (14). Blinding of operators and personnel involved with the animals was evaluated.

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7 3. Detection bias: Blinded outcome assessment and outcome assessment at random (i.e. test and control animals were randomly assessed) was evaluated. 4. Reporting bias: If available, comparisons between published protocols and eventually reported data were made. Selective reporting was further evaluated by comparing expected with actual outcome reporting. 5. Other bias, for example by industry sponsorship.

Data abstraction and study characteristics

Aggregated data was abstracted from each included study using pilot-tested spread-sheets. Data abstraction was independently performed by two reviewers (KFE, KJ) and eventually pooled, with consensus being reached by discussion or mediation by a third reviewer (CD). Missing information was retrieved from study authors if possible. The following outcomes were assessed: Study design (random or non-random allocation of interventions, parallelgroup or split-mouth study), animal model (in which animals and teeth were interventions performed), defect to be regenerated (what kind of defects were treated and how were they induced), stem/progenitor cells generation (source and preparation of stem/progenitor cells), carrier (type and preparation of carrier), intervention groups (what interventions were performed in which teeth, total and group sample size), examination (follow-ups and histological preparation and assessment), planned and reported outcomes (assessed from text, tables, or via evaluation of figures), funding information and reported conflict of interest. For further quantitative evaluation, data from the latest time point at which relevant outcomes were reported was used, as long-term effects are more relevant with regards to regeneration outcomes. Quantitative synthesis The unit of analysis for quantitative synthesis was the treated pulpal defect. To standardize the results of studies assessing the same outcome via different measurement parameters, we used standardized mean differences (SMD) and 95% confidence intervals (95%CI) as

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8 effect estimates (15). If studies reported separate estimates for subgroups of test and control interventions, those two interventions most closely fitting to the inclusion criteria– as decided by two reviewers (KFE, KJ) – were used for meta-analysis. Inverse generic meta-analysis was performed using Comprehensive Meta-Analysis 2.2.64 (Biostat, Englewood, NJ, USA). Heterogeneity was assessed using Cochran’s Q and I²-statistics (16). Since heterogeneity was mostly found to be substantial (I2>50%), random-effect models were used for metaanalysis. Given the low number of included studies, no subgroup or meta-regression analyses were performed. Publication bias was assessed using Funnel plots as well as Egger regression intercept test (17). Note that given the low number of included studies (see below), the outcomes of such tests should be interpreted with caution. Results Our search yielded 1364 records, with 92 articles being possibly eligible after review on abstract level and hand searching. 87 studies were excluded (Tab. S2), whilst five studies were included, reporting about 64 animals and 222 pulps (Fig. 1). Two of these studies allocated treatment and controls at random (18, 19), whilst three used a non-random design. All studies were published between 2004 and 2013, and used parallel-group designs. All but one study (19) used dogs as experimental animals. Four studies transplanted allogenic stem/progenitor cells into the experimental defects, while one study transplanted autogenous cells (20). All stem/progenitor cells were isolated from adult animal dental pulps, except for a one study obtaining the cells from the pulps of deciduous teeth (19). Two studies selected subcultures from the pulp stem/progenitor cells for transplantation (21, 22). Follow-up ranged between 28 and 180 days (median 90 days). Pulpal, dentinal, vascular, and neuronal regeneration were reported histologically by three, two, one and one studies, respectively (Tab. 1). Regeneration was investigated on multiple hematoxylin and eosin stained histological sections taken at intervals ranging from 100 µm to 150 µm in conjunction with digital imaging techniques. For vascular and neural regeneration assessments, staining via BS1-lectin and PGP9.5 was conducted, respectively, to facilitate specific quantification.

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9 Consequently, ratios of the regenerated pulpal, dentinal, vascular or neural tissues to the experimentally created defects were calculated for quantification purposes (Tab. 2). Two studies did not quantitatively report results from the scaffold/carrier or no treatment group (20, 22). In these cases, no pulpal or dentinal regeneration was assumed, with standard deviations being imputed (0.0001) for quantitative synthesis (see below). We checked for the impact of this assumption using sensitivity analysis. Risk of bias of included studies was generally high, with high risk of selection, performance and detection bias in all included studies (Tab. 3). Additionally, four of the five studies were published by the same group, which might raise doubts regarding the generalizability of the results. All studies were funded by the authors’ institutions and the authors reported no potential conflict of interest. Pooling data from three studies (7/7 animals and 23/23 treated pulps in test/control group, respectively), the regenerated pulpal area was found to be significantly larger after stem/progenitor cell transplantation than after control transplantation (SMD [95%CI] = 3.12 [0.38-6.26]). This estimate decreased, but remained statistically significantly in favor of transplantation when imputed estimates were omitted from the analysis. Neither funnel plot inspection nor Egger-test indicated publication bias. Pooling data from two studies (5/3 animals and 29/21 treated pulps in test/control group, respectively), dentinal regeneration was found to be significantly larger after stem/progenitor cell transplantation than after control transplantation (SMD = 6.91 [5.39-8.43]). This remained statistically significantly in favor of transplantation when imputed estimates were omitted. For both comparisons, substantial statistical heterogeneity was present (Fig. 2). Only one study (18) with 3/3 animals and 12/12 treated test/control teeth reported vascular and neural regeneration, and found the regenerated capillary area (SMD=5.10 [3.45-6.75]) and regenerated neural area (SMD=8.85 [6.23-11.50]) to be significantly larger after stem/progenitor cell transplantation compared with the control (Fig. 2). Discussion

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10 Pulpal tissue regeneration is a hard fought goal in regenerative endodontology (3, 23). The efficacy of pulpal tissue regeneration has been predominantly assessed using qualitative histological approaches, with only few studies applying quantitative evaluations (defining and quantifying the amount of the experimentally regenerated tissues). A challenge to the quantitative assessment of a successful pulp-dentin complex regeneration remains the definition of the primary regenerative outcomes; whether neural, vascular, soft or hard tissue/dentinal regeneration. The current systematic review explored the current quantitative evidence of the capacity of stem/progenitor cells to regenerate the pulp-dentin complex in animals. Interpretation of the results from this systematic review should be made with caution and balanced according to the limited number and quality of included studies. None of the studies had performed sample size calculations, resulting in limited statistical power. The choice of experimental animals was not standardised as well (four studies employed an experiment model in dogs, while one study used a mini-pig model), and further heterogeneity stemmed from differences in the creation of experimental defects, which comprised pulp chamber defects (19) and partially (22) or completely removed or amputated pulps with variable apical foramen enlargement (18, 20, 21). No sound evidence exists as to which of these models is most suitable to mimic the pathophysiology in humans. Moreover, no splitmouth designs were applied in the animal models to reduce inter-individual variability, whilst clustering of statistical units within the same animal was common, which artificially decreases statistical variation. Randomization of treatments to defects was performed in only two studies (18, 19), while blinding of the examiners was reported in only one study (19). Overall, studies were at high risk of selection, performance, detection and reporting bias. Except for one study using autogenous stem/progenitor cell transplantation (20) all studies transplanted allogenically isolated stem/progenitor cells. All stem/progenitor cells were isolated from pulps of adult animals, except for a single study obtaining the cells from the pulps of deciduous teeth (19). The selection of different subcultures from the pulp

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11 stem/progenitor cells in two of the studies (21, 22) adds to the mentioned heterogeneity. No evidence exists regarding the influence of such subculture selection on the properties of the cells and their regenerative outcomes. The selection of the biomaterial/scaffold used to support the stem/progenitor cells’ delivery is critical in influencing the treatment outcome and the regenerated tissue types (24). Ideally the scaffold should mimic the cells’ microenvironment, giving the required structural signals, adhesion molecules and pore size for homing, differentiation and phenotypic acquisition (25), while allowing cell-cell and cell-matrix interactions (26). Even minute differences in the scaffolds geometry, pore size, elasticity, mechanical properties, chemical composition and degradation rate can greatly influence the cells regenerative behaviour in vivo (23, 27). In the analysed studies, the scaffold/carrier selection was closely related to the design of the experimental defect, with mineralized β-TCP used for capping of pulp defects, whilst those studies with partial to complete pulpal removal/amputation used cell pellets in the absence of a scaffold, or applied cells on different collagen carriers to conform to the respective pulp chamber form. Again, these scaffolds have not been sufficiently and comparatively validated a priori, whilst potentially affecting the transplanted cells’ attributes, including cell proliferation rate and differentiation (28). Due to the complexity of pulpal tissues, no universally accepted primary outcome is currently available to assess pulp-dentin complex regeneration. However, a consensus exist about the importance of neural and vascular re-innervation for successful pulp-dentin complex regeneration (29). Four regenerative outcomes were investigated by the present review, namely regenerated pulp area, regenerated dentinal area, capillaries per total surface, and nerves per total surface. Insufficient studies were present to draw conclusions regarding vascular and neuronal regeneration. All outcomes had been assessed using the described specific or unspecific histological assessments. Functional pulp regeneration, however, additionally requires evidence of thermal or electric pulp testing results, which assess whether there is response to a stimulus mainly by functional Aδ fibres innervation, in addition to using pulse oximetry or laser Doppler ﬂowmetry evaluating the pulp’s vascular supply both

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12 with high sensitivity and specificity (30). Apart from a significant correlation recorded in case of an absence of vitality response and complete pulpal necrosis, the pulpal histological status generally poorly correlate with vitality testing results (30), posing a limitation in relying solely on histological methods and requiring the combination with additional functional innervation and vascularization tests to comprehensively assess functional pulp-dentin complex regeneration. The fact that four of the five studies included in the quantitative synthesis were conducted by the same group might further impact on the generalizability of the findings (18, 20-22). Despite that stem/progenitor cell transplanted defects showed significantly larger regenerated pulpal and dentinal regeneration than no-stem/progenitor cells transplantation controls histologically, the clinical relevance of these effects remains unclear. Moreover, the need to impute values for control groups increases the uncertainty within the estimates, whilst sensitivity analyses did not find our findings to be greatly altered when omitting these values from the analysis. The variability in outcome reporting calls for a defined set of outcomes for animal studies investigating pulp-dentin complex regeneration. Conclusion Stem/progenitor cell transplantation seems to enhance pulp-dentin complex regeneration in intra-oral animal models in vivo. However, these findings are based on a small number of included studies, with greatly deviant models, different interventions and controls, and high inherent risk of bias. Thus, our results should be interpreted with caution. Future studies should apply an accepted and standardised methodology and use a defined set of outcomes that best represent functional regeneration of pulpal tissues in humans. These outcomes should be assessed comprehensively, i.e. using other than histologic means, with comparable and reproducible methods used for evaluating pulpal regeneration. Current evidence levels are insufficient for further conclusions. Acknowledgements

Tissue Engineering Part B: Reviews Stem/progenitor cell transplantation for pulpal regeneration: A systematic review and meta-analysis of animal studies (doi: 10.1089/ten.TEB.2014.0675) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof. Page 13 of 46

13

This study was funded by the authors’ institutions.

Declaration of conflict of interest

The authors declare no conflict of interest.

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14 References 1. Setzer, F.C., andKim, S. Comparison of long-term survival of implants and endodontically treated teeth. J Dent Res 93, 19, 2014. 2. Nakashima, M., andAkamine, A. The application of tissue engineering to regeneration of pulp and dentin in endodontics. J Endod 31, 711, 2005. 3. Rosa, V., Zhang, Z., Grande, R.H., andNor, J.E. Dental pulp tissue engineering in fulllength human root canals. J Dent Res 92, 970, 2013. 4. Psaltis, P.J., Zannettino, A.C., Worthley, S.G., andGronthos, S. Concise review: mesenchymal stromal cells: potential for cardiovascular repair. Stem Cells 26, 2201, 2008. 5. Monsarrat, P., Vergnes, J.N., Nabet, C., Sixou, M., Snead, M.L., Planat-Benard, V., Casteilla, L., andKemoun, P. Concise Review: Mesenchymal Stromal Cells Used for Periodontal Regeneration: A Systematic Review. Stem Cell Transl Med 3, 768, 2014. 6. Ilic, D., andPolak, J. Stem cell based therapy--where are we going? Lancet 379, 877, 2012. 7. Shin, L., andPeterson, D.A. Human mesenchymal stem cell grafts enhance normal and impaired wound healing by recruiting existing endogenous tissue stem/progenitor cells. Stem Cells Transl Med 2, 33, 2013. 8. Hynes, K., Menicanin, D., Gronthos, S., andBartold, P.M. Clinical utility of stem cells for periodontal regeneration. Periodontol 2000 59, 203, 2012. 9. Wu, Y., Chen, L., Scott, P.G., andTredget, E.E. Mesenchymal stem cells enhance wound healing through differentiation and angiogenesis. Stem Cells 25, 2648, 2007. 10. Shi, Y., Hu, G., Su, J., Li, W., Chen, Q., Shou, P., Xu, C., Chen, X., Huang, Y., Zhu, Z., Huang, X., Han, X., Xie, N., andRen, G. Mesenchymal stem cells: a new strategy for immunosuppression and tissue repair. Cell Res 20, 510, 2010. 11. Dominici, M., Le Blanc, K., Mueller, I., Slaper-Cortenbach, I., Marini, F., Krause, D., Deans, R., Keating, A., Prockop, D., andHorwitz, E. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy 8, 315, 2006. 12. Mao, J.J., andProckop, D.J. Stem cells in the face: tooth regeneration and beyond. Cell stem cell 11, 291, 2012. 13. Kim, S.G., Zheng, Y., Zhou, J., Chen, M., Embree, M.C., Song, K., Jiang, N., andMao, J.J. Dentin and dental pulp regeneration by the patient's endogenous cells. Endodontic topics 28, 106, 2013. 14. Hooijmans, C., Rovers, M., de Vries, R., Leenaars, M., Ritskes-Hoitinga, M., andLangendam, M. SYRCLE's risk of bias tool for animal studies. BMC medical research methodology 14, 43, 2014. 15. Higgins, J.P.T., andGreen, S. Cochrane handbook for systematic reviews of interventions. Version 5.10 (updated March 2011): The Cochrane Collaboration. 2011. 16. Higgins, J.P.T., andThompson, S.G. Quantifying heterogeneity in a meta-analysis. Statistics in medicine 21, 1539, 2002. 17. Egger, M., Smith, G.D., Schneider, M., andMinder, C. Bias in meta-analysis detected by a simple, graphical test. BMJ 315, 629, 1997. 18. Iohara, K., Murakami, M., Takeuchi, N., Osako, Y., Ito, M., Ishizaka, R., Utunomiya, S., Nakamura, H., Matsushita, K., andNakashima, M. A Novel Combinatorial Therapy With Pulp Stem Cells and Granulocyte Colony-Stimulating Factor for Total Pulp Regeneration. Stem Cell Transl Med 2, 521, 2013. 19. Zheng, Y., Wang, X.Y., Wang, Y.M., Liu, X.Y., Zhang, C.M., Hou, B.X., andWang, S.L. Dentin Regeneration Using Deciduous Pulp Stem/Progenitor Cells. J Dent Res 91, 676, 2012. 20. Nakashima, M., Iohara, K., Ishikawa, M., Ito, M., Tomokiyo, A., Tanaka, T., andAkamine, A. Stimulation of reparative dentin formation by ex vivo gene therapy using dental pulp stem cells electrotransfected with growth/differentiation factor 11 (Gdf11). Hum Gene Ther 15, 1045, 2004.

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15 21. Iohara, K., Imabayashi, K., Ishizaka, R., Watanabe, A., Nabekura, J., Ito, M., Matsushita, K., Nakamura, H., andNakashima, M. Complete Pulp Regeneration After Pulpectomy by Transplantation of CD105(+) Stem Cells with Stromal Cell-Derived Factor-1. Tissue Eng Pt A 17, 1911, 2011. 22. Iohara, K., Zheng, L., Ito, M., Ishizaka, R., Nakamura, H., Into, T., Matsushita, K., andNakashima, M. Regeneration of dental pulp after pulpotomy by transplantation of CD31()/CD146(-) side population cells from a canine tooth. Regen Med 4, 377, 2009. 23. Albuquerque, M.T., Valera, M.C., Nakashima, M., Nor, J.E., andBottino, M.C. Tissueengineering-based Strategies for Regenerative Endodontics. J Dent Res 93, 1222, 2014. 24. Kolind, K., Leong, K.W., Besenbacher, F., andFoss, M. Guidance of stem cell fate on 2D patterned surfaces. Biomaterials 33, 6626, 2012. 25. Chen, F.M., Wu, L.A., Zhang, M., Zhang, R., andSun, H.H. Homing of endogenous stem/progenitor cells for in situ tissue regeneration: Promises, strategies, and translational perspectives. Biomaterials 32, 3189, 2011. 26. Chen, F.M., Zhang, J., Zhang, M., An, Y., Chen, F., andWu, Z.F. A review on endogenous regenerative technology in periodontal regenerative medicine. Biomaterials 31, 7892, 2010. 27. Tevlin, R., McArdle, A., Atashroo, D., Walmsley, G.G., Senarath-Yapa, K., Zielins, E.R., Paik, K.J., Longaker, M.T., andWan, D.C. Biomaterials for Craniofacial Bone Engineering. J Dent Res 2014. 28. Sundelacruz, S., andKaplan, D.L. Stem cell- and scaffold-based tissue engineering approaches to osteochondral regenerative medicine. Seminars in cell & developmental biology 20, 646, 2009. 29. Zhang, W., andYelick, P.C. Vital pulp therapy-current progress of dental pulp regeneration and revascularization. International journal of dentistry 2010, 856087, 2010. 30. Gopikrishna, V., Pradeep, G., andVenkateshbabu, N. Assessment of pulp vitality: a review. International journal of paediatric dentistry / the British Paedodontic Society [and] the International Association of Dentistry for Children 19, 3, 2009.


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16

Tables


17

Tissue Engineering Part B: Reviews em/progenitor cell transplantation for pulpal regeneration: A systematic review and meta-analysis of animal studies (doi: 10.1089/ten.TEB.2014.067 been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ f

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Study

Study design

Stem cells; source

Blind; random; design No; random; parallel

Animal model

Defects

Carrier/ scaffold

Groups (bold: test & control)

72 incisors; 18 dogs

whole pulp removed, apical foramen enlarged to 0.6 mm

Atelocollagen; collagen

DPSCs; allogenic

Blind; random; parallel

56 premolars; 7 mini- pigs

pulp chamber defects (3-4 mm diameter)

β-TCP scaffolds

(1) DPSCs/G-CSF/atelocollagen (2) total pulp cells/ G-CSF (3) DPSCs (4) total pulp cells (5) G-CSF (6) Collagen (1) Ca(OH)2 (2) β-TCP (3) DPSCs/β-TCP

Iohara et al. 2009

No; no; parallel

54 canines; 18 dogs

pulp partial removal 1mm under the cervical line

Mixture of collagen type I & III (1:1)

primary pulp cells; allogenic

Nakashim a et al. 2004

No; no; parallel

24 teeth; 6 dogs

pulps amputated

No carrier/ scaffold

(1) CD31-/CD146- cells (2)CD31+ /CD146- cells, (3) no pellet (4) scaffold only (5) CD31-/CD146- cells (6) CD31+ /CD146- cells (7) scaffold only (8) CD31-/CD146- cells (9) CD31+ /CD146- cells (10) scaffold only (groups 1-4 harvested after 14 days for histology, groups 5-7 harvested after 30 days and groups 8-10 harvested after 60 days) (1) Gdf11-transfected pellets (2) pEGFP-transfected pellets (3) no transplantation

Iohara et al. 2011

No; no; parallel

60 incisors; 15 dogs

whole pulp removal; enlargement of apical foramen to 0.7 mm

Mixture of collagen type I & III

(1) Pulp CD105+ cells + SDF-1, (2) Adipose CD105+ cells + SDF-1 (3) Total pulp cells + SDF-1 (4) SDF-1 only, (5) Pulp CD105+ (6) scaffold (7) Pulp CD105+ cells + SDF-1 (8) CD105+ cells with SDF-1, adipose CD105+ with SDF-1 and total pulp cells with SDF-1 (9) normal teeth (groups 1-6 harvested after 14 days, group 7 after 28 and group 8 after 90 days)

dental pulp cells; allogenic

Iohara et al. 2013

Zheng et al. 2012

Pulp tissue regeneration (regenerated pulp area/root canal total area (%))

Test N; mean±SD DPSCs 12; 13.5±5.5

Control N; mean±SD Collagen 12; 9.6±2.9

SHEDs; allogenic

CD31/CD1466; 121.1±17.2

DPSCs/β -TCP 24; 81.4±7.3

β-TCP

pEGFPtransfect ed pellets 5; 0.32± 0.077

no transplan tation 2; 0

16; 34.6±4.5

CD31+ /CD1466; 57.2±7.9

DPSCs; autogenous

CD105+ 5; 9.81±3.8

Dentin regeneration (regenerated dentin/ total defect area (%) or tubular reparative dentin in mm²) Test Control N; N; mean±SD mean±SD

Scaffold 5; 4.3±1.6

Vascularization (capillaries/total surface (%))

Neural regeneration (nerves/total surface (%))






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Abbreviations: DPSCs: dental pulp stem cells, SHEDs: stem cells from human deciduous teeth, β-TCP: β-tri calcium phosphate, Ca(OH)2: Calcium hydroxide, G-CSF: Granulocytes colony stimulating factor, Gdf11: growth/differentiation factor 11, SDF-1: stromal cell-derived factor, SP: Side population

Table 1: Included studies


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Pulp tissue regeneration

Dentin regeneration

Vascularization

Neural regeneration

 Paraffin sections (5 μm in thickness) were histomorphologically examined after staining with hematoxylin and eosin (HE). For examining relative amounts of regenerated tissue, three sections at 150-μm intervals for each tooth were measured on a binocular microscope (Leica, M 205 FA) and the surface area of these outlines was determined by using Leica Application Suite software (Leica, version 3.4.1). Ratio of regenerated root canal area per root canal total area measured on the histological sections. Data are means ±SD of five determinations. The experiment was repeated three times (Iohara et al. 2013).

 Measurements were done at six different positions from the buccal to the lingual side. Sections of 5 to 6 μm thickness from the embedded specimen were stained with H&E. The area of mineralization was analysed semiquantitatively by one blinded histological expert using histomorphometric techniques (Imagepro Express, Bethesda, MD, USA). The amount of the regenerated dentin was expressed as a percentage of regenerated dentin in the total defect area (means ±SD) (Zheng et al. 2012).

 Paraffin sections 5 µm in thickness were stained with H&E. Capturing of video images of the histological preparations on a Keyence BZ-9000 fluorescence microscope (Keyence, Tokyo, Japan) or a binocular microscope (Leica, M 205 FA). Three sections at intervals 150 µm of each tooth were examined. On-screen image outlines of newly regenerated pulp tissues were traced and the surface area of these outlines in the cavity of the amputated pulp was determined by a BZ-II analyser software (Keyence) or Leica Application Suite software. The ratio of regenerated area to cavity area on the amputated pulp was calculated in three sections of each tooth and means ±SD determined (Iohara et al. 2009, 2011).

 Dentin formation was examined in a series of paraffin sections stained with H&E. Each sample was examined by capturing video images of the histological preparations. Five sections at 100 µm intervals from each tooth were examined. On-screen image outlines of reparative dentin was traced, and the surface area of these outlines in the cavity of amputated pulp was determined with NIH Image 1.62 software. Results expressed as millimetre square (means ±SD) (Nakashima et al. 2004).

 50-μm-thick paraffin sections were deparaffinized and stained with Fluorescein Griffonia (Bandeiraea) Simplicifolia Lectin 1/fluorescein-galanthus nivalis (snowdrop) lectin (BS-1 lectin). Ratio of positively stained area by BS1-lectin for capillaries per root canal total area were measured on histological sections in a frame composed of 310 µm × 240 µm. Microscopic digital images of six sections every 120 µm were scanned in the frame. Data are means ±SD of five determinations. The experiment was repeated three times (Iohara et al. 2013).

 Free floating 50-μmthick paraffin sections were deparaffinized and incubated for 15 minutes with 0.3% Triton X-100 (Sigma). After incubation with 2.0% normal goat serum to block non-specific binding, they were incubated with rabbit antihuman PGP9.5 (Ultra Clone) (1:10,000) at 4°C overnight. Bound antibodies were further reacted with Fluoresceinconjugated Donkey anti-rabbit IgG secondary antibody (Jackson ImmunoResearch, Baltimore) (1:200) for 1 hour at room temperature. Ratio of positively stained area (by PGP9.5) of neurites per root canal total area were measured on histological sections in a frame composed of 310 µm × 240 µm. Microscopic digital images of six sections every 120 µm were scanned in the frame. Data are means ±SD of five determinations. The experiment was repeated three times (Iohara et al. 2013).


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Table 2: Outcome measurement for dental pulpal regeneration

Abbreviations: H&E: Hematoxylin and eosin, SD: standard deviation.

Table 2: Outcome measurement for dental pulpal regeneration

Tissue Engineering Part B: Reviews em/progenitor cell transplantation for pulpal regeneration: A systematic review and meta-analysis of animal studies (doi: 10.1089/ten.TEB.2014.067 been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ f Page 23 of 46

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Page 24 of 46

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Study

Selection bias

Performance bias

Sequence

Baseline

Allocation

Random

generation

characteristics

concealment

housing

Blinding

Detection bias

Attrition

Reporting

bias

bias

Incomplete

Selective

Other sources

outcome

outcome

reporting

of bias

assessment

data

Random

Blinding

Other bias

Iohara 2009

no

yes

no

unclear

no

no

no

unclear

unclear

no

Iohara 2011

no

yes

no

unclear

no

no

no

unclear

unclear

no

Iohara 2013

yes

yes

unclear

unclear

no

no

no

unclear

no

no

no

yes

no

unclear

no

no

no

unclear

no

no

yes

yes

no

unclear

no

yes

no

unclear

unclear

no

Nakashima 2004 Zheng 2012

Table 2: Risk of bias

Table 3: Risk of bias


25


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Figure legends


27


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29

Figure 1: Flow-chart of study selection. Details of studies excluded at full-text stage can be found within the appendix.


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Figure 2: Meta-analysis for pulpal, vascular and dentinal regeneration of pulpal defects after stem/progenitor cell or control transplantation. Study data, standardized mean differences (SMD) and 95% confidence intervals (95% CI), relative weight (%), pooled effect estimates for different outcomes (bold) from random-effects meta-analysis are presented. Heterogeneity was assessed using Cochran’s Q and I2-statistics, and publication bias was evaluated using Egger test if more than two studies were pooled. For pulpal and dentinal regeneration, we imputed missing values from control groups (indicated by asterisk). Omitting these values from the analysis decreased the effect estimates, but did not change the level of statistical significance (asterisks, thin-lined diamonds). Z overall test statistics, p level of significance.


31

Appendix

Supplementary Table 1: Search sequence for PubMed

Supplementary Table 2: Excluded studies with reasons for exclusion


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33


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Page 35 of 46


35 Appendix Supplementary Table 1: Search sequence for PubMed Search ((((((((((((((((((((((((((((((((((((((((((((((((((((("stem cell") OR "stem cells") OR "progenitor cells") OR "progenitor cell") OR "stem/progenitor cell") OR "stem/progenitor cells") OR "stem progenitor cell") OR "precursor cell") OR "precursor cells") OR "precursor stem cells") OR "pluripotent stem cells") OR "pluripotent stem cell") OR "pluripotent cell") OR "pluripotent cells") OR "multipotent cells") OR "multipotent cell") OR "multipotent stem cell") OR "multipotent stem cells") OR "omnipotent stem cells") OR "omnipotent stem cell") OR "omnipotent cell") OR "omnipotent cells") OR "totipotent cells") OR "totipotent cell") OR "totipotent stem cell") OR "totipotent stem cells") OR "embryonic stem cells") OR "embryonic stem cell") OR "embryonic cell") OR "embryonic cells") OR "undifferentiated cell") OR "alkaline phosphatase positive cell") OR "alkaline phosphatase positive cells") OR "ips cells") OR "ips cell") OR "ips") OR "MSCs") OR "MSC") OR "reserve cell") OR "mother cell") OR "mother cells") OR "vegetative cells") OR "vegetative cell") OR "unspecialized cells") OR "unspecialized cell") OR "somatic cells") OR "somatic cell") OR "parent cell") OR "mesenchymal stem cell") OR "mesenchymal stem cells") OR "mesenchymal cell") OR "mesenchymal cells")) AND ((((((((((("pulp progress") OR "pulp curing") OR "pulp cure") OR "pulp mending") OR "pulp regrowth") OR "pulp healing") OR "pulp tissue") OR "pulp treatment") OR "pulp therapy") OR "pulp regeneration") OR "pulp")

Supplementary Table 2: Excluded studies Number Study 1 Abe S, Hamada K, Miura M, Yamaguchi S (2012). Neural crest stem cell property of apical pulp cells derived from human developing tooth. Cell biology international 36(10):927-936. 2 Al-Hazaimeh N, Beattie J, Yang X, Duggal M (2012). Vasculogenic differentiation of dental pulp stromal cells in vitro and in vivo. Cell and tissue

Reason for exclusion Ectopic transplantation (subcutaneous)

Ectopic transplantation (subcutaneous)

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3

4

5

6

7

8

9

10

11

research. Almushayt A, Narayanan K, Zaki AE, George A (2006). Dentin matrix protein 1 induces cytodifferentiation of dental pulp stem cells into odontoblasts. Gene therapy 13(7):611620. Alongi DJ, Yamaza T, Song Y, Fouad AF, Romberg EE, Shi S et al. (2010). Stem/progenitor cells from inflamed human dental pulp retain tissue regeneration potential. Regenerative medicine 5(4):617-631. Ballini A, De Frenza G, Cantore S, Papa F, Grano M, Mastrangelo F et al. (2007). In vitro stem cell cultures from human dental pulp and periodontal ligament: new prospects in dentistry. International journal of immunopathology and pharmacology 20(1):9-16. Blitz N, Serota KS (1995). Rehabilitation of the endodontically treated tooth: exploding the myths, defining the future. Oral health 85(12):19-24; quiz 24. Chen B, Sun HH, Wang HG, Kong H, Chen FM, Yu Q (2012). The effects of human platelet lysate on dental pulp stem cells derived from impacted human third molars. Biomaterials 33(20):5023-5035. Choung HW, Lee JH, Lee DS, Choung PH, Park JC (2013). The role of preameloblast-conditioned medium in dental pulp regeneration. Journal of molecular histology 44(6):715-721. Cordeiro MM, Dong Z, Kaneko T, Zhang Z, Miyazawa M, Shi S et al. (2008). Dental pulp tissue engineering with stem cells from exfoliated deciduous teeth. Journal of endodontics 34(8):962-969. d'Aquino R, De Rosa A, Laino G, Caruso F, Guida L, Rullo R et al. (2009). Human dental pulp stem cells: from biology to clinical applications. Journal of experimental zoology Part B, Molecular and developmental evolution 312b(5):408-415. Dangaria SJ, Ito Y, Luan X, Diekwisch

No stem cell transplantation


Review

Review




Review


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12

13

14

15

16

17

18

19

20

TG (2011). Successful periodontal ligament regeneration by periodontal progenitor preseeding on natural tooth root surfaces. Stem cells and development 20(10):1659-1668. Galler KM, Cavender AC, Koeklue U, Suggs LJ, Schmalz G, D'Souza RN (2011). Bioengineering of dental stem cells in a PEGylated fibrin gel. Regenerative medicine 6(2):191-200. Glick M (2009). Stem cell research and oral health. Journal of the American Dental Association (1939) 140(5):512, 514. Goldberg M, Smith AJ (2004). Cells and extracellular matrices of dentin and pulp: A biological basis for repair and tissue engineering. Critical reviews in oral biology and medicine : an official publication of the American Association of Oral Biologists 15(1):1327. Gotlieb EL, Murray PE, Namerow KN, Kuttler S, Garcia-Godoy F (2008). An ultrastructural investigation of tissueengineered pulp constructs implanted within endodontically treated teeth. Journal of the American Dental Association (1939) 139(4):457-465. Gronthos S, Mankani M, Brahim J, Robey PG, Shi S (2000). Postnatal human dental pulp stem cells (DPSCs) in vitro and in vivo. Proceedings of the National Academy of Sciences of the United States of America 97(25):13625-13630. Gronthos S, Brahim J, Li W, Fisher LW, Cherman N, Boyde A et al. (2002). Stem cell properties of human dental pulp stem cells. Journal of dental research 81(8):531-535. Gronthos S (2011). The therapeutic potential of dental pulp cells: more than pulp fiction? Cytotherapy 13(10):1162-1163. Guo W, Gong K, Shi H, Zhu G, He Y, Ding B et al. (2012). Dental follicle cells and treated dentin matrix scaffold for tissue engineering the tooth root. Biomaterials 33(5):1291-1302. Harichane Y, Dimitrova-Nakov S,

Ectopic transplatation (subcutaneous)

Review

Review


Ectopic transplantation (dorsal surface)


Review

No quantitative analysis

No pulpal regeneration model

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21

22

23

24

25

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Poliard A, Goldberg M, Kellermann O (2010). P43-implantation of odontoblast progenitors in the rat molar pulp leads to the formation of reparative osteodentin. Bulletin du Groupement international pour la recherche scientifique en stomatologie & odontologie 49(3):109-110. Harichane Y, Hirata A, DimitrovaNakov S, Granja I, Goldberg A, Kellermann O et al. (2011). Pulpal progenitors and dentin repair. Advances in dental research 23(3):307312. He J (2006). Recent advances and future directives in pulp biology. Practical procedures & aesthetic dentistry : PPAD 18(1):49-50, 52. Huang GT, Yamaza T, Shea LD, Djouad F, Kuhn NZ, Tuan RS et al. (2010). Stem/progenitor cell-mediated de novo regeneration of dental pulp with newly deposited continuous layer of dentin in an in vivo model. Tissue engineering Part A 16(2):605-615. Hung CN, Mar K, Chang HC, Chiang YL, Hu HY, Lai CC et al. (2011). A comparison between adipose tissue and dental pulp as sources of MSCs for tooth regeneration. Biomaterials 32(29):6995-7005. Iohara K, Nakashima M, Ito M, Ishikawa M, Nakasima A, Akamine A (2004). Dentin regeneration by dental pulp stem cell therapy with recombinant human bone morphogenetic protein 2. Journal of dental research 83(8):590-595. Iohara K, Murakami M, Nakata K, Nakashima M (2014). Age-dependent decline in dental pulp regeneration after pulpectomy in dogs. Experimental gerontology 52(39-45. Ishizaka R, Iohara K, Murakami M, Fukuta O, Nakashima M (2012). Regeneration of dental pulp following pulpectomy by fractionated stem/progenitor cells from bone marrow and adipose tissue. Biomaterials 33(7):2109-2118. James D (2010). Stem cell visits. British


Review




Missing "no stem cells" control

Missing "no stem cells" control

Review

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29

30

31

32

33

34

35

36

dental journal 209(6):263. Ji YM, Jeon SH, Park JY, Chung JH, Choung YH, Choung PH (2010). Dental stem cell therapy with calcium hydroxide in dental pulp capping. Tissue engineering Part A 16(6):18231833. Jing W, Wu L, Lin Y, Liu L, Tang W, Tian W (2008). Odontogenic differentiation of adipose-derived stem cells for tooth regeneration: necessity, possibility, and strategy. Medical hypotheses 70(3):540-542. Jung HS, Lee DS, Lee JH, Park SJ, Lee G, Seo BM et al. (2011). Directing the differentiation of human dental follicle cells into cementoblasts and/or osteoblasts by a combination of HERS and pulp cells. Journal of molecular histology 42(3):227-235. Kerkis I, Kerkis A, Dozortsev D, StukartParsons GC, Gomes Massironi SM, Pereira LV et al. (2006). Isolation and characterization of a population of immature dental pulp stem cells expressing OCT-4 and other embryonic stem cell markers. Cells, tissues, organs 184(3-4):105-116. Khan FR, Ahmad T, Badruddin N (2011). Stem cells and tissue engineering in dentistry--a myth or reality. JPMA The Journal of the Pakistan Medical Association 61(6):619. Kim J, Park JC, Kim SH, Im GI, Kim BS, Lee JB et al. (2014). Treatment of FGF2 on stem cells from inflamed dental pulp tissue from human deciduous teeth. Oral diseases 20(2):191-204. Kodonas K, Gogos C, Papadimitriou S, Kouzi-Koliakou K, Tziafas D (2012). Experimental formation of dentin-like structure in the root canal implant model using cryopreserved swine dental pulp progenitor cells. Journal of endodontics 38(7):913-919. Kuo TF, Lin HC, Yang KC, Lin FH, Chen MH, Wu CC et al. (2011). Bone marrow combined with dental bud cells promotes tooth regeneration in miniature pig model. Artificial organs





Review




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37

38

39

40

41

42

43

44

35(2):113-121. Lacerda-Pinheiro S, Jegat N, Septier D, Priam F, Bonnefoix M, Bitard J et al. (2006). Early in vivo and in vitro effects of amelogenin gene splice products on pulp cells. European journal of oral sciences 114 Suppl 1(232-238; discussion 254-236, 381-232. Lacerda-Pinheiro S, Marchadier A, Donas P, Septier D, Benhamou L, Kellermann O et al. (2008). An In vivo Model for Short-Term Evaluation of the Implantation Effects of Biomolecules or Stem Cells in the Dental Pulp. The open dentistry journal 2(67-72. Lacerda-Pinheiro S, Dimitrova-Nakov S, Harichane Y, Souyri M, Petit-Cocault L, Legres L et al. (2012). Concomitant multipotent and unipotent dental pulp progenitors and their respective contribution to mineralised tissue formation. European cells & materials 23(371-386. Laino G, Graziano A, d'Aquino R, Pirozzi G, Lanza V, Valiante S et al. (2006). An approachable human adult stem cell source for hard-tissue engineering. Journal of cellular physiology 206(3):693-701. Lee JH, Lee DS, Choung HW, Shon WJ, Seo BM, Lee EH et al. (2011). Odontogenic differentiation of human dental pulp stem cells induced by preameloblast-derived factors. Biomaterials 32(36):9696-9706. Lei G, Yan M, Wang Z, Yu Y, Tang C, Wang Z et al. (2011). Dentinogenic capacity: immature root papilla stem cells versus mature root pulp stem cells. Biology of the cell / under the auspices of the European Cell Biology Organization 103(4):185-196. Liao J, Al Shahrani M, Al-Habib M, Tanaka T, Huang GT (2011). Cells isolated from inflamed periapical tissue express mesenchymal stem cell markers and are highly osteogenic. Journal of endodontics 37(9):12171224. Lovelace TW, Henry MA, Hargreaves






Ectopic transplantation (renal capsules)



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46

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48

49

50

51

52

KM, Diogenes A (2011). Evaluation of the delivery of mesenchymal stem cells into the root canal space of necrotic immature teeth after clinical regenerative endodontic procedure. Journal of endodontics 37(2):133-138. Mao JJ, Giannobile WV, Helms JA, Hollister SJ, Krebsbach PH, Longaker MT et al. (2006). Craniofacial tissue engineering by stem cells. Journal of dental research 85(11):966-979. Mao JJ (2009). Stem cells and dentistry. Journal of dental hygiene : JDH / American Dental Hygienists' Association 83(4):173-174. Mohamadreza BE, Khorsand A, Arabsolghar M, Paknejad M, Ghaedi B, Rokn AR et al. (2012). Autologous Dental Pulp Stem Cells in Regeneration of Defect Created in Canine Periodontal Tissue. The Journal of oral implantology. Nakashima M (1990a). An ultrastructural study of the differentiation of mesenchymal cells in implants of allogeneic dentine matrix on the amputated dental pulp of the dog. Archives of oral biology 35(4):277-281. Nakashima M (1990b). The induction of reparative dentine in the amputated dental pulp of the dog by bone morphogenetic protein. Archives of oral biology 35(7):493-497. Nakashima M, Mizunuma K, Murakami T, Akamine A (2002). Induction of dental pulp stem cell differentiation into odontoblasts by electroporationmediated gene delivery of growth/differentiation factor 11 (Gdf11). Gene therapy 9(12):814-818. Nakashima M, Reddi AH (2003). The application of bone morphogenetic proteins to dental tissue engineering. Nature biotechnology 21(9):10251032. Nakashima M, Tachibana K, Iohara K, Ito M, Ishikawa M, Akamine A (2003). Induction of reparative dentin formation by ultrasound-mediated gene delivery of

Review

Review





Review

No stem cell transplanation

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55

56

57

58

59

60

61

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growth/differentiation factor 11. Human gene therapy 14(6):591-597. Nakashima M (2005). Tissue engineering in endodontics. Australian endodontic journal : the journal of the Australian Society of Endodontology Inc 31(3):111-113. Nakashima M, Iohara K (2011). Regeneration of dental pulp by stem cells. Advances in dental research 23(3):313-319. Okamoto Y, Sonoyama W, Ono M, Akiyama K, Fujisawa T, Oshima M et al. (2009). Simvastatin induces the odontogenic differentiation of human dental pulp stem cells in vitro and in vivo. Journal of endodontics 35(3):367372. Park JY, Jeon SH, Choung PH (2011). Efficacy of periodontal stem cell transplantation in the treatment of advanced periodontitis. Cell transplantation 20(2):271-285. Ravindran S, Song Y, George A (2010). Development of three-dimensional biomimetic scaffold to study epithelialmesenchymal interactions. Tissue engineering Part A 16(1):327-342. Rosa V, Zhang Z, Grande RH, Nor JE (2013). Dental pulp tissue engineering in full-length human root canals. Journal of dental research 92(11):970975. Schmalz G, Galler KM (2011). Tissue injury and pulp regeneration. Journal of dental research 90(7):828-829. Shi S, Bartold PM, Miura M, Seo BM, Robey PG, Gronthos S (2005). The efficacy of mesenchymal stem cells to regenerate and repair dental structures. Orthodontics & craniofacial research 8(3):191-199. Shimizu A, Nakakura-Ohshima K, Noda T, Maeda T, Ohshima H (2000). Responses of immunocompetent cells in the dental pulp to replantation during the regeneration process in rat molars. Cell and tissue research 302(2):221-233. Song JS, Stefanik D, Damek-Poprawa M, Alawi F, Akintoye SO (2009).

Review



Periodontal model



Review



Ectopic transplantation (subcunateous)

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64

65

66

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Differentiation and regenerative capacities of human odontomaderived mesenchymal cells. Differentiation; research in biological diversity 77(1):29-37. Srisuwan T, Tilkorn DJ, Al-Benna S, Abberton K, Messer HH, Thompson EW (2013). Revascularization and tissue regeneration of an empty root canal space is enhanced by a direct blood supply and stem cells. Dental traumatology : official publication of International Association for Dental Traumatology 29(2):84-91. Stevens A, Zuliani T, Olejnik C, LeRoy H, Obriot H, Kerr-Conte J et al. (2008). Human dental pulp stem cells differentiate into neural crest-derived melanocytes and have label-retaining and sphere-forming abilities. Stem cells and development 17(6):11751184. Takeda T, Tezuka Y, Horiuchi M, Hosono K, Iida K, Hatakeyama D et al. (2008). Characterization of dental pulp stem cells of human tooth germs. Journal of dental research 87(7):676681. Tziafas D, Alvanou A, Panagiotakopoulos N, Smith AJ, Lesot H, Komnenou A et al. (1995). Induction of odontoblast-like cell differentiation in dog dental pulps after in vivo implantation of dentine matrix components. Archives of oral biology 40(10):883-893. Vakhrushev IV, Antonov EN, Popova AV, Konstantinova EV, Karalkin PA, Kholodenko IV et al. (2012). Design of tissue engineering implants for bone tissue regeneration of the basis of new generation polylactoglycolide scaffolds and multipotent mesenchymal stem cells from human exfoliated deciduous teeth (SHED cells). Bulletin of experimental biology and medicine 153(1):143-147. Wang J, Liu X, Jin X, Ma H, Hu J, Ni L et al. (2010). The odontogenic differentiation of human dental pulp stem cells on nanofibrous poly(L-lactic







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acid) scaffolds in vitro and in vivo. Acta biomaterialia 6(10):3856-3863. Wang Y, Zhao Y, Jia W, Yang J, Ge L (2013). Preliminary study on dental pulp stem cell-mediated pulp regeneration in canine immature permanent teeth. Journal of endodontics 39(2):195-201. Wei F, Song T, Ding G, Xu J, Liu Y, Liu D et al. (2013). Functional tooth restoration by allogeneic mesenchymal stem cell-based bio-root regeneration in swine. Stem cells and development 22(12):1752-1762. Wu G, Deng ZH, Fan XJ, Ma ZF, Sun YJ, Ma DD et al. (2009). Odontogenic potential of mesenchymal cells from hair follicle dermal papilla. Stem cells and development 18(4):583-589. Xiao L, Tsutsui T (2013). Human dental mesenchymal stem cells and neural regeneration. Human cell 26(3):91-96. Xu L, Tang L, Jin F, Liu XH, Yu JH, Wu JJ et al. (2009). The apical region of developing tooth root constitutes a complex and maintains the ability to generate root and periodontium-like tissues. Journal of periodontal research 44(2):275-282. Yamamura T (1985). Differentiation of pulpal cells and inductive influences of various matrices with reference to pulpal wound healing. Journal of dental research 64 Spec No(530-540. Yang KC, Wang CH, Chang HH, Chan WP, Chi CH, Kuo TF (2012a). Fibrin glue mixed with platelet-rich fibrin as a scaffold seeded with dental bud cells for tooth regeneration. Journal of tissue engineering and regenerative medicine 6(10):777-785. Yang X, Zhang S, Pang X, Fan M (2012b). Pro-inflammatory cytokines induce odontogenic differentiation of dental pulp-derived stem cells. Journal of cellular biochemistry 113(2):669677. Yen AH, Sharpe PT (2008). Stem cells and tooth tissue engineering. Cell and tissue research 331(1):359-372. Young CS, Kim SW, Qin C, Baba O,




Review

Ectopic transplantation (subrenal)

Review


Retracted

Review


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Butler WT, Taylor RR et al. (2005). Developmental analysis and computer modelling of bioengineered teeth. Archives of oral biology 50(2):259-265. Yu J, Deng Z, Shi J, Zhai H, Nie X, Zhuang H et al. (2006). Differentiation of dental pulp stem cells into regularshaped dentin-pulp complex induced by tooth germ cell conditioned medium. Tissue engineering 12(11):3097-3105. Yu J, Wang Y, Deng Z, Tang L, Li Y, Shi J et al. (2007). Odontogenic capability: bone marrow stromal stem cells versus dental pulp stem cells. Biology of the cell / under the auspices of the European Cell Biology Organization 99(8):465-474. Yu J, Jin F, Deng Z, Li Y, Tang L, Shi J et al. (2008). Epithelial-mesenchymal cell ratios can determine the crown morphogenesis of dental pulp stem cells. Stem cells and development 17(3):475-482. Yuan GH, Yang GB, Wu LA, Chen Z, Chen S (2010). Potential Role of Dentin Sialoprotein by Inducing Dental Pulp Mesenchymal Stem Cell Differentiation and Mineralization for Dental Tissue Repair. Dental hypotheses 1(2):69-75. Zhang C, Chang J, Sonoyama W, Shi S, Wang CY (2008). Inhibition of human dental pulp stem cell differentiation by Notch signaling. Journal of dental research 87(3):250-255. Zhang W, Abukawa H, Troulis MJ, Kaban LB, Vacanti JP, Yelick PC (2009). Tissue engineered hybrid tooth-bone constructs. Methods (San Diego, Calif) 47(2):122-128. Zhang W, Ahluwalia IP, Literman R, Kaplan DL, Yelick PC (2011). Human dental pulp progenitor cell behavior on aqueous and hexafluoroisopropanol based silk scaffolds. Journal of biomedical materials research Part A 97(4):414-422. Zhou J, Shi S, Shi Y, Xie H, Chen L, He Y et al. (2011). Role of bone marrowderived progenitor cells in the










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87 maintenance and regeneration of dental mesenchymal tissues. Journal of cellular physiology 226(8):20812090. Zhu X, Zhang C, Huang GT, Cheung GS, Dissanayaka WL, Zhu W (2012). Transplantation of dental pulp stem cells and platelet-rich plasma for pulp regeneration. Journal of endodontics 38(12):1604-1609. Nominal scale (0/1 for pulpal regeneration)

Allogeneic bone marrow mesenchymal stem cell transplantation for periodontal regeneration.

Recent Stem Cell Advances: Cord Blood and Induced Pluripotent Stem Cell for Cardiac Regeneration- a Review.

Lung transplantation following hematopoietic stem cell transplantation: report of two cases and systematic review of literature.

Hematopoietic stem cell transplantation in the leukodystrophies: a systematic review of the literature.

Ventral root axotomy regeneration after mesenchymal stem cell transplantation.

Systematic review and meta-analysis of autologous stem cell transplantation in peripheral T cell lymphoma.

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review.

Stem cell transplantation of matched sibling donors compared with immunosuppressive therapy for acquired severe aplastic anaemia: a Cochrane systematic review.

Efficacy of Mesenchymal Stem Cell Therapy for Steroid-Refractory Acute Graft-Versus-Host Disease following Allogeneic Hematopoietic Stem Cell Transplantation: A Systematic Review and Meta-Analysis.

Rituximab after autologous stem cell transplantation enhances survival of B-cell lymphoma patients: a meta-analysis and systematic review.

Allogeneic stem-cell transplantation for peripheral T-cell lymphoma: a systemic review and meta-analysis.

Stem cell therapy for intervertebral disk regeneration.

Stem cell-based approaches to improve nerve regeneration: potential implications for reconstructive transplantation?

Stem Cell Transplantation for Peripheral Nerve Regeneration: Current Options and Opportunities.

Safety of Cultivated Limbal Epithelial Stem Cell Transplantation for Human Corneal Regeneration.

Liver transplantation for hepatic tumors: a systematic review.

Sickle cell disease and pulpal necrosis: a review of the literature for the primary care dentist.

Stem cell transplantation in traumatic spinal cord injury: a systematic review and meta-analysis of animal studies.

Effects of stem cell transplantation on cognitive decline in animal models of Alzheimer's disease: A systematic review and meta-analysis.

Influence of cyclosporine on the occurrence of nephrotoxicity after allogeneic hematopoietic stem cell transplantation: a systematic review.

Sarcopenia in lung transplantation: a systematic review.

Experimental considerations concerning the use of stem cells and tissue engineering for facial nerve regeneration: a systematic review.

Hematopoietic stem cell transplantation for infantile osteopetrosis.

Allogeneic stem cell transplantation for thalassemia major.