B ro n c h o p u l m o n a r y D y s p l a s i a an d C h ro n i c L u n g D i s e a s e : Stem Cell Therapy Maria Pierro, MDa,b,*, Elena Ciarmoli, Bernard Thébaud, MD, PhDd,e,f
MD
c
,
KEYWORDS Bronchopulmonary dysplasia Prematurity Stem cells Newborn Clinical translation KEY POINTS In the past few years, increasing insight into stem cell biology has generated excitement about the potential of stem cells to repair, and perhaps to regenerate, damaged organs. Among stem cells, mesenchymal stromal (stem) cells (MSCs) have attracted much attention because of their ease of isolation, multilineage potential, and immunomodulatory properties. MSCs ameliorate many critical aspects of bronchopulmonary dysplasia pathogenesis in preclinical models by mitigating lung inflammation, inducing vascular and alveolar growth, and inhibiting lung fibrosis. MSCs are preferentially attracted to sites of injury where they exert their therapeutic effects thanks to the interaction with the immune system and to the paracrine secretion of anti-inflammatory, antioxidant, antiapoptotic, trophic, and proangiogenic factors. Several details, including timing of administration, route of administration, dose, cell source, and manufacturing processes of the final stem cell product, may influence success or failure of the therapy.
The authors have nothing to disclose. a Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca` Granda Ospedale Maggiore Policlinico, University of Milan, Via della Commenda 12, Milan 20122, Italy; b Neonatal Intensive Care Unit, IRCCS Istituto Giannina Gaslini, Via Gerolamo Gaslini, 5, Genova 16148, Italy; c Neonatal Intensive Care Unit, MBBM Foundation, San Gerardo Hospital, Via Pergolesi 33, Monza 20900, Italy; d Division of Neonatology, Department of Pediatrics, Children’s Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada; e Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, 501 Smyth Road, Ottawa, Ontario K1H8L6, Canada; f Department of Cellular and Molecular Medicine, Sinclair Institute of Regenerative Medicine, University of Ottawa, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada * Corresponding author. Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca` Granda Ospedale Maggiore Policlinico, University of Milan, Via della Commenda 12, Milan 20122, Italy. E-mail address: [email protected] Clin Perinatol 42 (2015) 889–910 http://dx.doi.org/10.1016/j.clp.2015.08.013 perinatology.theclinics.com 0095-5108/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
890
Pierro et al
INTRODUCTION
Despite continuous advances of perinatal care, bronchopulmonary dysplasia (BPD) remains a significant burden of extreme prematurity because it lacks a safe and effective treatment.1,2 In the past few years, increasing insight into stem cell biology has generated excitement about the potential of stem cells to regenerate damaged organs. Stem cells are primitive cells capable of extensive self-renewal with the potential to give rise to multiple differentiated cellular phenotypes. Stem cells play a crucial role in organogenesis and growth during the early stages of development, as well as in organ repair and regeneration throughout life.3 MESENCHYMAL STROMAL CELLS
Among stem cells, mesenchymal stromal (stem) cells (MSCs) have attracted much attention because of their ease of isolation, multilineage potential, and immunomodulatory properties.4 MSCs represent a broad and heterogeneous cell population, defined by 3 minimum criteria: (1) adhesion to plastic when cultured in a tissue culture flask under standard culturing conditions, (2) expression of specific surface markers (CD73, CD90, CD105) and lack of expression of hematopoietic markers, and (3) ability to differentiate into mesodermic (osteogenic, chondrogenic, and adipogenic) lineages on in vitro stimulation.4 DISRUPTION OF MESENCHYMAL STROMAL CELL HOMEOSTASIS IN THE EVENTS THAT LEAD TO BRONCHOPULMONARY DYSPLASIA
It is now generally accepted that MSCs reside in all tissues of the human body.5 Although all MSCs share the 3 minimum criteria, MSCs from different tissues, including lung-resident MSCs, also display distinct functional characteristics to support their specific microenvironment6 and are considered guardians of tissue repair and maintenance. The role of lung-resident MSCs in the development of BPD remains to be elucidated. Circulating and lung-resident MSCs number and function seems to be perturbed in human and experimental BPD.7–9 These findings provide a rational for exogenous supplementation of MSCs for the prevention or repair of neonatal lung injury.9 PRECLINICAL EVIDENCE OF MESENCHYMAL STROMAL CELL EFFECTS ON ARRESTED LUNG DEVELOPMENT Bronchopulmonary Dysplasia is an Arrest in Lung Development
BPD is a form of chronic lung disease, peculiar to the extremely premature infants, born at the early stages of pulmonary development, in whom lung growth may be permanently arrested. BPD lungs consist of enlarged and simplified breathing structures (Fig. 1A), typical of the canalicular stage, as opposed to the alveolar ducts at term, characterized by smaller, more numerous and more complex alveoli (see Fig. 1A), essential to ensure adequate gas exchange.10 The arrest of lung development, exacerbated by prenatal and postnatal proinflammatory stimuli (see Fig. 1), make traditional therapies ineffective in treating this disease.1 Animal Models of Arrested Lung Development: the Hyperoxia-Induced Lung Injury
Few models in different animal species have been able to mimic BPD or some of its aspects. Practically, all the studies testing the administration of MSCs in experimental BPD have been carried out in the rodent hyperoxia models.11,12 Rats and mice are
Bronchopulmonary Dysplasia and Chronic Lung Disease
Fig. 1. Arrest of alveolarization in human and experimental BPD and effects of MSCs. (A) Lung histology (newborn). (A1) Autopsy from a term infant who died at 5 months of life. The lung specimen shows numerous secondary crests and alveolar structures within the airspaces and alveolar ducts (AD). (A2) Ex-preterm infant with BPD. Lung specimen from an open lung biopsy at 8 months of age shows enlarged airspaces, ADs with alveolar simplification (arrow). (B) Lung histology (rat). (B1) Normoxic control rat pup at 21 days of life. Lungs show well-organized alveoli with numerous secondary crests (black arrow). (B2) Rat pup exposed to hyperoxia between 4 and 14 days of life. Lungs show enlarged and simplified alveoli (asterisk). (B3) Rat pup exposed to hyperoxia between 4 and 14 days of life and treated endotracheally with MSCs on day 4 of life. Lung architecture with secondary crests (black arrow) is preserved. (Adapted from [A] Coalson JJ. Pathology of new bronchopulmonary dysplasia. Semin Neonatol 2003;8:79, with permission; and [B] Reprinted with permission of the American Thoracic Society. Copyright Ó 2015 American Thoracic Society. van Haaften T, Byrne R, Bonnet S, et al. Airway delivery of mesenchymal stem cells prevents arrested alveolar growth in neonatal lung injury in rats. Am J Respir Crit Care Med 2009;180:1135. Official Journal of the American Thoracic Society.)
naturally born at the canalicular stage of lung development, equivalent to the developmental stage of extreme preterm infants. Exposure of the developing rat lung to various concentrations of hyperoxic gas during the alveolar stage (day 5 to day 14 of life) impairs normal alveolarization, resulting in fewer and enlarged alveolar air spaces, reminiscent of structural changes seen in human BPD11,12 (see Fig. 1B). Treatment with Mesenchymal Stromal Cells Ameliorates Hyperoxia-Induced Arrest in Lung Growth Prophylactic treatment
Prophylactic administration of MSCs (before exposure to hyperoxia) (Fig. 2) improves survival in experimental BPD and consistently and remarkably prevents lung injury (see Fig. 1B).9,13–17 Results seem to be most beneficial by endotracheal (ET), compared with intravenous (IV) or intraperitoneal, administration14 and dosedependent with no benefit at 5 103 (approximately 5 102/g body weight) and increased benefit from 5 104 (approximately 5 103 cells/g) to 5 105 cells (approximately 5 104 cells/g).15 Lung compliance and exercise tolerance are also significantly improved by ET administration of MSCs9,17 (Table 1). Effective results have
891
892
Pierro et al
Fig. 2. Experiments testing the therapeutic effect of MSCs in experimental BPD. Rats exposed to hyperoxia during the saccular stage (day 4 to 14 of life). MSCs can be administered prophylactically (before exposure to hyperoxia) or as rescue (after exposure to hyperoxia). In both scenarios, MSCs can be delivered through a systemic route, either intravenously (IV) or intraperitoneally (IP) or through local endotracheal (ET) administration.
been obtained with rodent bone marrow–derived MSCs (BM-MSCs)9,13 and human cord or cord blood–derived MSCs (hC-MSCs).13–17 Rescue treatment
Rescue administration of MSCs (after exposure to hyperoxia) (see Fig. 2), have led to less compelling results. Rat BM-MSCs elicited no response at a dose of 1 105,9 whereas hC-MSCs produced only a slight improvement with a dose of 5 105, as opposed to early treatment.16 However, in both rescue studies, the same absolute dose as the prophylactic experiments was used without adjusting for the increase in body weight of the older animals. When the dose was adjusted per body weight, although the prophylactic treatment still elicited a superior response, the rescue administration of hC-MSCs was able to ameliorate lung injury.17 Taken together, these data suggest a possible beneficial effect of rescue MSC treatment but early timing seems to be more efficient.
PRECLINICAL EVIDENCE OF MESENCHYMAL STROMAL CELL EFFECTS ON DISRUPTED VASCULAR DEVELOPMENT Hypoplastic Vascular Bed in Human Bronchopulmonary Dysplasia
BPD is also characterized by an abnormal distribution of pulmonary vessels and a reduction in the number of small arteries, which are functionally hyperreactive and hypertonic, culminating in pulmonary arterial hypertension and right ventricular hypertrophy.18 Early and late pulmonary hypertension, assessed by indirect echocardiographic measurements (Fig. 3A), is detected in approximately 20% to 25% of the infants with BPD and worsens outcome.18,19 Impaired pulmonary vascular growth may contribute to the irreversible arrest of lung development in BPD.20 Hyperoxia Induces Pulmonary Vascular Disruption and Pulmonary Hypertension
Exposure of term pups to hyperoxia simulates the typical vascular dysregulation of the dysplastic lung (Fig. 3C, D). Lung arterial vessels are reduced in number with thickened medial wall, resulting in right ventricular hypertrophy.11,12 Echocardiography
Table 1 Studies testing the therapeutic effect of stem or progenitor cells in experimental models of bronchopulmonary dysplasia Outcomes Experiment Ref Number Dose
Route Source
Timing
Alveolar Ctrl Cells Damage
Functional Data
1 105 5 1 104/g IT
Mouse-BM P4
PASMC
b
1 105 5 5 103/g IT
Mouse-BM P14
PASMC
13
—
5 104 5 1 104/g IV
Mouse-BM P4
No
Modest No reports improvement
14
a
5 105 5 5 104/g IT
hC
P5
Fibs
b
2 106 5 2 105/g IP
hC
P5
Fibs
a
3 105 5 3 104/g IT
hC
P4
Fibs
b
6 105 5 3 104/g IT
hC
P14
No
a b
5 103 5 5 102/g IT 5 104 5 5 103/g IT
hC hC
P5 P5
No No
c
5 105 5 5 104/g IT
hC
P5
No
a
5 105 5 5 104/kg 5 105 5 2.5 104/g 5 105 5 5 104/g1
IT
hC
P3
No
IT
hC
P10
No
IT
hC
P31P10 No
17
15
16
b c
Significant Improved exercise Decreased improvement capacity No effects Improved exercise No reports capacity
No reports
Improved
No reports
No reports
Decreased
Reduced
No reports
Significant No reports improvement No effects No reports
No reports
Reduced
No reports
No reports
Slightly Reduced
No reports
Significant Improved lung improvement compliance Modest No reports improvement
No reports
No reports
No reports
No reports
No reports
No reports
No effects No reports Modest No reports improvement Significant No reports improvement
No reports No reports
No effects Slightly reduced Extremely reduced
No effects Improved
Significant No reports improvement Modest No reports improvement Significant No repots improvement
No reports
Extremely reduced Slightly reduced Extremely reduced
Improved
No reports
No reports No reports
Improved
No effects Improved
Abbreviations: BM, bone marrow; Ctrl, control; Fibs, fibroblasts; hC, human cord; IP, intraperitoneal; IT, intratracheal; P, postnatal day; PASMC, pulmonary artery smooth muscle cells.
Bronchopulmonary Dysplasia and Chronic Lung Disease
a
9
Pulmonary Hypertension Inflammation Survival
893
894
C
1
Micro-Angio CT-Scan
Scanning Electron Microscopy
D Normoxia
Hyperoxia
Hyperoxia + MSC
Hyperoxia + PASMC
2
Normoxia
Hyperoxia Vessels/High Powered Field
300
B
*
250
P
MD
c
,
KEYWORDS Bronchopulmonary dysplasia Prematurity Stem cells Newborn Clinical translation KEY POINTS In the past few years, increasing insight into stem cell biology has generated excitement about the potential of stem cells to repair, and perhaps to regenerate, damaged organs. Among stem cells, mesenchymal stromal (stem) cells (MSCs) have attracted much attention because of their ease of isolation, multilineage potential, and immunomodulatory properties. MSCs ameliorate many critical aspects of bronchopulmonary dysplasia pathogenesis in preclinical models by mitigating lung inflammation, inducing vascular and alveolar growth, and inhibiting lung fibrosis. MSCs are preferentially attracted to sites of injury where they exert their therapeutic effects thanks to the interaction with the immune system and to the paracrine secretion of anti-inflammatory, antioxidant, antiapoptotic, trophic, and proangiogenic factors. Several details, including timing of administration, route of administration, dose, cell source, and manufacturing processes of the final stem cell product, may influence success or failure of the therapy.
The authors have nothing to disclose. a Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca` Granda Ospedale Maggiore Policlinico, University of Milan, Via della Commenda 12, Milan 20122, Italy; b Neonatal Intensive Care Unit, IRCCS Istituto Giannina Gaslini, Via Gerolamo Gaslini, 5, Genova 16148, Italy; c Neonatal Intensive Care Unit, MBBM Foundation, San Gerardo Hospital, Via Pergolesi 33, Monza 20900, Italy; d Division of Neonatology, Department of Pediatrics, Children’s Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada; e Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, 501 Smyth Road, Ottawa, Ontario K1H8L6, Canada; f Department of Cellular and Molecular Medicine, Sinclair Institute of Regenerative Medicine, University of Ottawa, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada * Corresponding author. Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca` Granda Ospedale Maggiore Policlinico, University of Milan, Via della Commenda 12, Milan 20122, Italy. E-mail address: [email protected] Clin Perinatol 42 (2015) 889–910 http://dx.doi.org/10.1016/j.clp.2015.08.013 perinatology.theclinics.com 0095-5108/15/$ – see front matter Ó 2015 Elsevier Inc. All rights reserved.
890
Pierro et al
INTRODUCTION
Despite continuous advances of perinatal care, bronchopulmonary dysplasia (BPD) remains a significant burden of extreme prematurity because it lacks a safe and effective treatment.1,2 In the past few years, increasing insight into stem cell biology has generated excitement about the potential of stem cells to regenerate damaged organs. Stem cells are primitive cells capable of extensive self-renewal with the potential to give rise to multiple differentiated cellular phenotypes. Stem cells play a crucial role in organogenesis and growth during the early stages of development, as well as in organ repair and regeneration throughout life.3 MESENCHYMAL STROMAL CELLS
Among stem cells, mesenchymal stromal (stem) cells (MSCs) have attracted much attention because of their ease of isolation, multilineage potential, and immunomodulatory properties.4 MSCs represent a broad and heterogeneous cell population, defined by 3 minimum criteria: (1) adhesion to plastic when cultured in a tissue culture flask under standard culturing conditions, (2) expression of specific surface markers (CD73, CD90, CD105) and lack of expression of hematopoietic markers, and (3) ability to differentiate into mesodermic (osteogenic, chondrogenic, and adipogenic) lineages on in vitro stimulation.4 DISRUPTION OF MESENCHYMAL STROMAL CELL HOMEOSTASIS IN THE EVENTS THAT LEAD TO BRONCHOPULMONARY DYSPLASIA
It is now generally accepted that MSCs reside in all tissues of the human body.5 Although all MSCs share the 3 minimum criteria, MSCs from different tissues, including lung-resident MSCs, also display distinct functional characteristics to support their specific microenvironment6 and are considered guardians of tissue repair and maintenance. The role of lung-resident MSCs in the development of BPD remains to be elucidated. Circulating and lung-resident MSCs number and function seems to be perturbed in human and experimental BPD.7–9 These findings provide a rational for exogenous supplementation of MSCs for the prevention or repair of neonatal lung injury.9 PRECLINICAL EVIDENCE OF MESENCHYMAL STROMAL CELL EFFECTS ON ARRESTED LUNG DEVELOPMENT Bronchopulmonary Dysplasia is an Arrest in Lung Development
BPD is a form of chronic lung disease, peculiar to the extremely premature infants, born at the early stages of pulmonary development, in whom lung growth may be permanently arrested. BPD lungs consist of enlarged and simplified breathing structures (Fig. 1A), typical of the canalicular stage, as opposed to the alveolar ducts at term, characterized by smaller, more numerous and more complex alveoli (see Fig. 1A), essential to ensure adequate gas exchange.10 The arrest of lung development, exacerbated by prenatal and postnatal proinflammatory stimuli (see Fig. 1), make traditional therapies ineffective in treating this disease.1 Animal Models of Arrested Lung Development: the Hyperoxia-Induced Lung Injury
Few models in different animal species have been able to mimic BPD or some of its aspects. Practically, all the studies testing the administration of MSCs in experimental BPD have been carried out in the rodent hyperoxia models.11,12 Rats and mice are
Bronchopulmonary Dysplasia and Chronic Lung Disease
Fig. 1. Arrest of alveolarization in human and experimental BPD and effects of MSCs. (A) Lung histology (newborn). (A1) Autopsy from a term infant who died at 5 months of life. The lung specimen shows numerous secondary crests and alveolar structures within the airspaces and alveolar ducts (AD). (A2) Ex-preterm infant with BPD. Lung specimen from an open lung biopsy at 8 months of age shows enlarged airspaces, ADs with alveolar simplification (arrow). (B) Lung histology (rat). (B1) Normoxic control rat pup at 21 days of life. Lungs show well-organized alveoli with numerous secondary crests (black arrow). (B2) Rat pup exposed to hyperoxia between 4 and 14 days of life. Lungs show enlarged and simplified alveoli (asterisk). (B3) Rat pup exposed to hyperoxia between 4 and 14 days of life and treated endotracheally with MSCs on day 4 of life. Lung architecture with secondary crests (black arrow) is preserved. (Adapted from [A] Coalson JJ. Pathology of new bronchopulmonary dysplasia. Semin Neonatol 2003;8:79, with permission; and [B] Reprinted with permission of the American Thoracic Society. Copyright Ó 2015 American Thoracic Society. van Haaften T, Byrne R, Bonnet S, et al. Airway delivery of mesenchymal stem cells prevents arrested alveolar growth in neonatal lung injury in rats. Am J Respir Crit Care Med 2009;180:1135. Official Journal of the American Thoracic Society.)
naturally born at the canalicular stage of lung development, equivalent to the developmental stage of extreme preterm infants. Exposure of the developing rat lung to various concentrations of hyperoxic gas during the alveolar stage (day 5 to day 14 of life) impairs normal alveolarization, resulting in fewer and enlarged alveolar air spaces, reminiscent of structural changes seen in human BPD11,12 (see Fig. 1B). Treatment with Mesenchymal Stromal Cells Ameliorates Hyperoxia-Induced Arrest in Lung Growth Prophylactic treatment
Prophylactic administration of MSCs (before exposure to hyperoxia) (Fig. 2) improves survival in experimental BPD and consistently and remarkably prevents lung injury (see Fig. 1B).9,13–17 Results seem to be most beneficial by endotracheal (ET), compared with intravenous (IV) or intraperitoneal, administration14 and dosedependent with no benefit at 5 103 (approximately 5 102/g body weight) and increased benefit from 5 104 (approximately 5 103 cells/g) to 5 105 cells (approximately 5 104 cells/g).15 Lung compliance and exercise tolerance are also significantly improved by ET administration of MSCs9,17 (Table 1). Effective results have
891
892
Pierro et al
Fig. 2. Experiments testing the therapeutic effect of MSCs in experimental BPD. Rats exposed to hyperoxia during the saccular stage (day 4 to 14 of life). MSCs can be administered prophylactically (before exposure to hyperoxia) or as rescue (after exposure to hyperoxia). In both scenarios, MSCs can be delivered through a systemic route, either intravenously (IV) or intraperitoneally (IP) or through local endotracheal (ET) administration.
been obtained with rodent bone marrow–derived MSCs (BM-MSCs)9,13 and human cord or cord blood–derived MSCs (hC-MSCs).13–17 Rescue treatment
Rescue administration of MSCs (after exposure to hyperoxia) (see Fig. 2), have led to less compelling results. Rat BM-MSCs elicited no response at a dose of 1 105,9 whereas hC-MSCs produced only a slight improvement with a dose of 5 105, as opposed to early treatment.16 However, in both rescue studies, the same absolute dose as the prophylactic experiments was used without adjusting for the increase in body weight of the older animals. When the dose was adjusted per body weight, although the prophylactic treatment still elicited a superior response, the rescue administration of hC-MSCs was able to ameliorate lung injury.17 Taken together, these data suggest a possible beneficial effect of rescue MSC treatment but early timing seems to be more efficient.
PRECLINICAL EVIDENCE OF MESENCHYMAL STROMAL CELL EFFECTS ON DISRUPTED VASCULAR DEVELOPMENT Hypoplastic Vascular Bed in Human Bronchopulmonary Dysplasia
BPD is also characterized by an abnormal distribution of pulmonary vessels and a reduction in the number of small arteries, which are functionally hyperreactive and hypertonic, culminating in pulmonary arterial hypertension and right ventricular hypertrophy.18 Early and late pulmonary hypertension, assessed by indirect echocardiographic measurements (Fig. 3A), is detected in approximately 20% to 25% of the infants with BPD and worsens outcome.18,19 Impaired pulmonary vascular growth may contribute to the irreversible arrest of lung development in BPD.20 Hyperoxia Induces Pulmonary Vascular Disruption and Pulmonary Hypertension
Exposure of term pups to hyperoxia simulates the typical vascular dysregulation of the dysplastic lung (Fig. 3C, D). Lung arterial vessels are reduced in number with thickened medial wall, resulting in right ventricular hypertrophy.11,12 Echocardiography
Table 1 Studies testing the therapeutic effect of stem or progenitor cells in experimental models of bronchopulmonary dysplasia Outcomes Experiment Ref Number Dose
Route Source
Timing
Alveolar Ctrl Cells Damage
Functional Data
1 105 5 1 104/g IT
Mouse-BM P4
PASMC
b
1 105 5 5 103/g IT
Mouse-BM P14
PASMC
13
—
5 104 5 1 104/g IV
Mouse-BM P4
No
Modest No reports improvement
14
a
5 105 5 5 104/g IT
hC
P5
Fibs
b
2 106 5 2 105/g IP
hC
P5
Fibs
a
3 105 5 3 104/g IT
hC
P4
Fibs
b
6 105 5 3 104/g IT
hC
P14
No
a b
5 103 5 5 102/g IT 5 104 5 5 103/g IT
hC hC
P5 P5
No No
c
5 105 5 5 104/g IT
hC
P5
No
a
5 105 5 5 104/kg 5 105 5 2.5 104/g 5 105 5 5 104/g1
IT
hC
P3
No
IT
hC
P10
No
IT
hC
P31P10 No
17
15
16
b c
Significant Improved exercise Decreased improvement capacity No effects Improved exercise No reports capacity
No reports
Improved
No reports
No reports
Decreased
Reduced
No reports
Significant No reports improvement No effects No reports
No reports
Reduced
No reports
No reports
Slightly Reduced
No reports
Significant Improved lung improvement compliance Modest No reports improvement
No reports
No reports
No reports
No reports
No reports
No reports
No effects No reports Modest No reports improvement Significant No reports improvement
No reports No reports
No effects Slightly reduced Extremely reduced
No effects Improved
Significant No reports improvement Modest No reports improvement Significant No repots improvement
No reports
Extremely reduced Slightly reduced Extremely reduced
Improved
No reports
No reports No reports
Improved
No effects Improved
Abbreviations: BM, bone marrow; Ctrl, control; Fibs, fibroblasts; hC, human cord; IP, intraperitoneal; IT, intratracheal; P, postnatal day; PASMC, pulmonary artery smooth muscle cells.
Bronchopulmonary Dysplasia and Chronic Lung Disease
a
9
Pulmonary Hypertension Inflammation Survival
893
894
C
1
Micro-Angio CT-Scan
Scanning Electron Microscopy
D Normoxia
Hyperoxia
Hyperoxia + MSC
Hyperoxia + PASMC
2
Normoxia
Hyperoxia Vessels/High Powered Field
300
B
*
250
P
