Scholarly article on topic 'Two-Year Follow-Up Outcomes of Premature Infants Enrolled in the Phase I Trial of Mesenchymal Stem Cells Transplantation for Bronchopulmonary Dysplasia'

Two-Year Follow-Up Outcomes of Premature Infants Enrolled in the Phase I Trial of Mesenchymal Stem Cells Transplantation for Bronchopulmonary Dysplasia Academic research paper on "Clinical medicine"

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{"mesenchymal stem cells" / "cell transplantation" / "infant / premature" / "cord blood stem cell transplantation" / "bronchopulmonary dysplasia"}

Abstract of research paper on Clinical medicine, author of scientific article — So Yoon Ahn, Yun Sil Chang, Ji Hye Kim, Se In Sung, Won Soon Park

Objective To determine the long-term safety and outcomes of mesenchymal stem cells (MSCs) for bronchopulmonary dysplasia in premature infants enrolled in a previous phase I clinical trial up to 2 years of corrected age (CA). Study design We assessed serious adverse events, somatic growth, and respiratory and neurodevelopmental outcomes at visit 1 (4-6 months of CA), visit 2 (8-12 months of CA), and visit 3 (18-24 months of CA) in a prospective longitudinal follow-up study up to 2 years' CA of infants who received MSCs (MSC group). We compared these data with those from a historical case-matched comparison group. Results One of 9 infants in the MSC group died of Enterobacter cloacae sepsis at 6 months of CA, the remaining 8 infants survived without any transplantation-related adverse outcomes, including tumorigenicity. No infant in the MSC group was discharged with home supplemental oxygen compared with 22% in the comparison group. The average rehospitalization rate in the MSC group was 1.4/patient because of respiratory infections during 2 years of follow-up. The mean body weight of the MSC group at visit 3 was significantly higher compared with that of the comparison group. No infant in the MSC group was diagnosed with cerebral palsy, blindness, or developmental delay; in the comparison group, 1 infant was diagnosed with cerebral palsy and 1 with developmental delay. Conclusions Intratracheal transplantation of MSCs in preterm infants appears to be safe, with no adverse respiratory, growth, and neurodevelopmental effects at 2 years' CA. Trial registration ClinicalTrials.gov: NCT01632475.

Academic research paper on topic "Two-Year Follow-Up Outcomes of Premature Infants Enrolled in the Phase I Trial of Mesenchymal Stem Cells Transplantation for Bronchopulmonary Dysplasia"

ARTICLE IN PRESS

The Journal of Pediatrics • www.jpeds.com

ORIGINAL

ARTICLES

Two-Year Follow-Up Outcomes of Premature Infants Enrolled in the Phase I Trial of Mesenchymal Stem Cells Transplantation for Bronchopulmonary Dysplasia

So Yoon Ahn, MD, PhD1*, Yun Sil Chang, MD, PhD123*, Ji Hye Kim, MD, PhD4, Se In Sung, MD, PhD1, and

Won Soon Park , MD , PhD1' 2 ■ 3

Objective To determine the long-term safety and outcomes of mesenchymal stem cells (MSCs) for bronchopulmonary dysplasia in premature infants enrolled in a previous phase I clinical trial up to 2 years of corrected age (CA).

Study design We assessed serious adverse events, somatic growth, and respiratory and neurodevelopmental outcomes at visit 1 (4-6 months of CA), visit 2 (8-12 months of CA), and visit 3 (18-24 months of CA) in a prospective longitudinal follow-up study up to 2 years' CA of infants who received MSCs (MSC group). We compared these data with those from a historical case-matched comparison group.

Results One of 9 infants in the MSC group died of Enterobacter cloacae sepsis at 6 months of CA, the remaining 8 infants survived without any transplantation-related adverse outcomes, including tumorigenicity. No infant in the MSC group was discharged with home supplemental oxygen compared with 22% in the comparison group. The average rehospitalization rate in the MSC group was 1.4/patient because of respiratory infections during 2 years of follow-up. The mean body weight of the MSC group at visit 3 was significantly higher compared with that of the comparison group. No infant in the MSC group was diagnosed with cerebral palsy, blindness, or developmental delay; in the comparison group, 1 infant was diagnosed with cerebral palsy and 1 with developmental delay. Conclusions Intratracheal transplantation of MSCs in preterm infants appears to be safe, with no adverse respiratory, growth, and neurodevelopmental effects at 2 years' CA. (J Pediatr 2017MWM^-^W). Trial registration ClinicalTrials.gov: NCT01632475.

Bronchopulmonary dysplasia (BPD), a chronic lung disease that occurs in premature infants receiving prolonged oxygen and ventilator therapy, is a serious complication of preterm birth.1 BPD remains an important cause of mortality and long-term respiratory morbidities such as airway hyperreactivity, poor lung function, asthma, or chronic obstructive pulmonary disease,2 and neurologic morbidities such as developmental delay and cerebral palsy in survivors.3

Moreover, because the risk for developing BPD correlates with the extent of immaturity,4 recent improvements in the survival of the most immature infants have resulted in increased rates of BPD.5 Therefore, developing new effective therapies to prevent BPD in premature infants is an urgent and crucial issue.

Recently, we and others demonstrated that the exogenous transplantation of mesenchymal stem cells (MSCs) significantly attenuate hyperoxic lung injury in newborn animal models.6-16 Based on this promising experimental evidence, a phase I clinical trial was conducted, which revealed that single intratracheal transplantation Fr°T the1Department Pediat(ricsj Samsung Medical

' & r Center, Sungkyunkwan University School of Medicine;

of allogenic MSCs in very preterm infants at high risk for developing BPD was 2DePartment °f Hea|th Sciences and Te^^gy,

r r rr . . 'ii Samsung Advanced Institute for Health Sciences &

safe, feasible, and potentially efficacious in attenuating BPD compared with that Technology, Sungkyunkwan University; 3Stem Cell and

in a historical control group matched for gestational age, birth weight, and re- CRenteenreSaeoVuel MReedpCuibnlecIofsKu:eaSaanmdsuDgpMa:t;;;ceanlt of spiratory severity.17 However, the long-term safety and benefits of MSC ft^togy^^rtwfoMmagmg^^ce, a^mg

L ' ' o / Medical Center, Sungkyunkwan University School of

Medicine, Republic of Korea

"Contributed equally.

Funded by the Korean Health and Medical Technology R&D Program, Ministry for Health, Welfare and Family Affairs, Republic of Korea (A102136). Samsung Medical Center and MEDIPOST Co., Ltd have issued or filed patents for ''Method of treating lung diseases using cells separated or proliferated from umbilical cord blood'' under the name of Yun Sil Chang, Won Soon Park, and Yoon Sun Yang (CT/KR2007/000535). The other authors declare no conflicts of interest.

BPD Bronchopulmonary dysplasia

BSID-II Bayley Scales of Infant Development-Second Edition

CA Corrected age

CAT Cognitive adaptive scale

CLAMS Clinical linguistic and auditory milestone scale

DQ Developmental quotient

LMS Lambda, mu, and sigma

MDI Mental developmental index

MRI Magnetic resonance imaging

MSCs Mesenchymal stem cells

PDI Psychomotor developmental index

SAEs Serious adverse events

Portions of this study were presented as a poster during the Pediatric Academic Society meeting, Vancouver, BC, Canada, May 3-6, 2014.

0022-3476/$ - see front matter. © 2017 The Authors). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). http://dx.doi.org10.1016/jjpeds.2017.02.061

transplantation in growth, respiratory outcomes, and neurodevelopmental outcomes in very preterm infants transplanted with MSCs remains unknown.

In the present study, we investigated the long-term safety, growth, respiratory outcomes, and developmental outcomes of the very preterm infants who were enrolled in the phase I study of MSCs transplantation for BPD, until 24 months of corrected age (CA). This follow-up study was presented to the parents during the period of the phase clinical 1 trial.

Methods

As previously reported, the primary study was an open label, single center, dose escalation phase I clinical trial of a single intratracheal transplantation of allogenic human umbilical cord blood-derived MSCs to 9 very preterm infants at high risk for developing BPD. The infants had a mean gestational age of 25.3 ± 0.9 weeks and a mean birth weight of 793 ± 127 g, and received MSCs at a mean age of 10.4 ± 2.6 days after birth.17 The first 3 infants were given a low dose (1 X 107 cells/kg in 2 mL/kg of saline), and the next 6 were given a high dose (2 X 107 cells/kg in 4 mL/kg of saline). The MSCs were administered intratracheally in 2 fractions, using the same method for administering surfactant. The primary goal was to demonstrate the safety of intratracheal allogenic MSCs transplantation in very preterm infants, and the secondary goal was to evaluate the feasibility and potential efficacy of MSCs transplantation for BPD compared with a historical case-matched comparison group.

Nine infants discharged alive and whose parents agreed that the infant could be enrolled in the study, were prospectively followed up until 24 months of CA. The primary goal was to determine the long-term safety of MSCs transplantation in the enrolled infants up to 24 months of CA. Safety was defined as the absence of treatment-related serious adverse events (SAEs), according to the Consolidated Standards of Reporting Trials.18 An SAE was defined as an untoward medical occurrence that resulted in death, or was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, or resulted in persistent or significant disability. The secondary goal was to evaluate the potential long-term effects of MSCs transplantation on growth, respiratory outcomes, and neurodevelopmental outcomes up to 24 months of CA.

Infants were evaluated at 4-6 months, 8-12 months, and 18-24 months of CA in the Neonatal High Risk Follow-up Clinic of Samsung Medical Center (Figure 1; available at www.jpeds.com). At each visit, infants were examined with standard outcome assessments, including ascertainment of growth, respiratory health status, and neurodevelopmental outcomes by using a standardized follow-up interview, growth measurements, and thorough physical and neurologic examinations. In the standardized interview with parents, all medication use (including bronchodilators, inhaled/systemic steroids, and home oxygen therapy), the occurrence of wheezing or whistling sounds in the chest, and rehospitalization since the last visit were documented. The infants' height, body weight, and head circumference were measured for growth assessment, and these values

were converted to the sex- and age-specific z score of weight, height, and head circumference. Z scores were obtained using formulae based on the lambda, mu, and sigma (LMS) method, and sex- and age-specific LMS variables were obtained with reference to the database for 2007 Korean National Growth Charts.19 Catch-up growth was defined as >10th percentile weight, height, or head circumference according to the 2007 Korean National Growth Charts.19 At 18-24 months of CA, the neurodevelopmental outcome was evaluated with the mental developmental index (MDI) and psychomotor developmental index (PDI) of the Bayley Scales of Infant Development-Second Edition (BSIDII); neurodevelopmental delay was defined as MDI or PDI score <70. Blindness was defined as no useful vision in either eye. Deafness was defined as requiring hearing amplification aids in both ears. Cerebral palsy was defined as a Palisano gross motor function score >2. Brain magnetic resonance imaging (MRI) was performed for all surviving infants at 18-24 months of CA. The cognitive adaptive scale (CAT) and clinical linguistic and auditory milestone scale (CLAMS) was administered by a pediatric rehabilitation specialist as part of a comprehensive developmental assessment. The score on the CLAMS was based on the parent's report of language skill attainment. The score on the CAT was based on the child's performance with the administered items. The scores from the CAT/ CLAMS were expressed as developmental quotients (DQs = developmental age/chronologic age X 100).

The historical comparison group of the study included 2-year follow up of 2 matched infants for each MSCs transplantation patient (enrolled from February to September 2011); a nested comparison group enrolled in our previously reported phase I clinical trial, matched for birth between January 2009 and November 2011, gestational age within 3 days, birth weight within 50 g, as well as similar ventilator modes and mean respiratory severity scores (mean airway pressure X fraction of inspired oxygen) within 24 hours before MSCs transplantation. Clinical data including mortality, home oxygen at first discharge, growth measurements, and developmental outcomes up to 24 months of CA were obtained from a retrospective review of medical records.

This follow-up study protocol was approved by the institutional review board of the Samsung Medical Center in Seoul, Korea (No. 2013-10-052), and this study was registered on ClinicalTrials.gov (NCT01632475). Informed consent for this follow-up study was obtained from both parents of each child after review with the principal investigator or study staff.

Statistical Analyses

Continuous variables were summarized as mean and SD, and categorical variables were summarized by counts and percentages. Continuous anthropometric outcomes, such as weight, height, and head circumference, and their z scores were compared between the 2 study groups using the 2-sample t test and Wilcoxon rank sum test, additionally. Using histograms, we confirmed that their distributions were not severely skewed. Categorical anthropometric outcomes and neurodevelopmental outcomes were associated using Fisher exact test. Two-sided P values less than 5% were considered statistically signifi-

Table I. SAEs during follow-up of 24 months of CA

Patients A1 A2 A3 B1 B2 B3 B4 B5 B6

Gestational age (wk) 25+6 25+3 24+3 24+0 24+4 25+4 25+0 26+4 26+1

Birth weight (g) 770 870 720 630 740 850 650 1030 880

BPD severity Mild Mild Mild Mild Mod Mild Mod Mod Mild

Survival N Y Y Y Y Y Y Y Y

Cause of death Sepsis/enteritis

Respiratory Sx-related re-hospitalization

First admission

CA (mo) 0.5 mo (June) 4 mo (Oct) 4 mo (Dec) 7 mo (May) 12 mo (Dec) 5 mo (May)

Admission/ventilator care duration (d) 6/3 7/0 5/0 4/0 2/0 15/0

Proved pathogen — — Rhino Rhino — Parainfl

Second admission

CA (mo) 1 mo (July) 10 mo (Aug) 10 mo (Oct)

Admission/ventilator care duration (d) 7/0 7/0 6/0

Proved pathogen — — RSV

Third admission

CA (mo) 7 mo (Jan) 12 mo (Oct)

Admission/ventilator care duration (d) 3/0 6/0

Proved pathogen — —

Mod, moderate; N, no; Parainfl, parainfluenza virus; Rhino, rhinovirus; RSV, respiratory syncytial virus; Sx, symptom; Y yes.

cant. All statistical analyses were conducted using SAS v 9.4 (SAS Institute Inc, Cary, North Carolina).

Results

Table I shows SAEs, including mortality and rehospitalization that occurred up to 24 months of CA, in the infants who received MSCs transplantation who had been enrolled from February to September 2011. One infant, after discharge at 4 months of CA, suffered Enterobacter cloacae sepsis with subsequent disseminated intravascular coagulation despite appropriate antibiotic treatment. Although autopsy was not performed, no clinical evidence associated this SAE with MSCs transplantation.

The 8 surviving infants who received MSCs transplantation were rehospitalized at an average of 1.4 times (range, 0-3) because of respiratory infection during the 24 months of follow-up period (Table I). Of the total 11 rehospitalizations, 6 (55%)

occurred during the first autumn-winter season, and the identified pathogens included 2 rhinoviruses, 1 parainfluenza virus, and 1 respiratory syncytial virus in a patient who did not receive palivizumab prophylaxis. No infant who received MSCs transplantation was rehospitalized because of respiratory infection after 12 months of CA. No infant who received MSCs transplantation showed any abnormality, such as a visible mass lesion, in the chest radiograph taken at visit 3.

In the comparison group, 4 of 18 (22%) infants were discharged with oxygen therapy for an average duration of 33 days (range, 15-60 days). No infant who received MSCs transplantation was discharged with supplemental oxygen. No infant who received MSCs transplantation was diagnosed with asthma or required continuous steroid/bronchodilator treatment up to 24 months of CA.

Body weight, height, and head circumference were measured at each visit. Table II shows comparisons of age- and

Table II. Anthropometric measurements at 18-24 months of CA

Matched-control group (n = 14) MSC transplantation group (n = 8) P value

Weight, kg 10.3 ± 1.2 11.4 ± 1.0 .04

(10.4, 8.5-14.9) (11.6,10.0-13.0) .06*

Z score for weight for age -1.6 ± 0.9 -0.7 ± 0.8 .04

(-1.6, -3.3-1.7) (-0.6, -1.9-0.3) .05*

Height, cm 85.4 ± 2.6 85.1 ± 2.6 .96

(85.6, 80.4-90.0) (85.4, 81.2-90.0) .95*

Z score for height for age -0.2 ± 0.8 -0.3 ± 0.7 .32

(-0.2, -1.8-1.1) (-0.3, -1.6-0.8) .32*

Head circumference, cm 46.2 ± 1.7 47.0 ± 1.0 .23

(45.8, 43.5-49.0) (47.0, 45.0-48.2) .26*

Z score for head circumference for age -1.2 ± 1.0 -0.8 ± 0.6 .98

(-1.2, -3.0-0.2) (-0.7, -1.9-0.1) .97*

Weight catch-up 36% (5) 62% (5) .38

Height catch-up 86% (12) 87% (7) .34

Head circumference catch-up 57% (8) 86% (6) .15

Data are presented as number and percentage of total or mean ± SD with (median ± range). *P value assessed by Wilcoxon rank sum test.

Figure 2. Growth profiles of infants until the CA of 24 months. Age- and sex-specific z scores of body weight, height, and head circumference.

sex-specific converted standardized z scores in the 8 surviv-

ing infants who received MSCs transplantation with data for

14 out of 18 infants from the matched comparison group who could be followed up to 24 months of CA. There were no significant differences in body weight, length/height, and head circumference measured at visit 1 and 2 (4-6 months of CA and 8-12 months of CA); the mean body weight, but not length/ height or head circumference, was significantly higher in the patients who received MSCs transplantation compared with that in the case control group at visit 3 (18-24 months of CA)

(Figure 2, Table II). There were no significant differences in the catch-up growth, defined as >10th percentile in body weight, height, or head circumference, between the 2 study groups at visit 3 (Table II).

Neurodevelopmental outcomes were assessed at visit 3(18-24 months of CA) in the 8 surviving infants who received MSCs transplantation and in 14 of the 18 infants from the matched control group who could be followed up to 24 months of CA

(Table III). No infant who received MSCs transplantation was

f- ->

Table III. Neurodevelopmental outcomes

Matched-control MSC transplantation

group group P value

(n = 14) (n = 8)

Cerebral palsy 7% (1/14) 0% (0/8) 1.0

Hearing aid 0% (0/14) 0% (0/8) —

Blindness 0% (0/14) 0% (0/8) —

BSID-II scores (n = 10) (n = 8)

MDI 88 ± 18 89 ± 15 .95

(86, 58-110) (86,70-112) .94*

PDI 86 ± 9 95 ± 14 .13

(84, 73-100) (96,73-114) .14*

MDI <70 10% (1/10) 0% (0/8) 1.0

PDI <70 0% (0/10) 0% (0/8) —

Data are presented as number and percentage of total or mean ± SD and (median ± range). *P value assessed by Wilcoxon rank sum test.

diagnosed with cerebral palsy, deafness, or blindness. In the comparison group, 1 infant with severe BPD and recurrent seizures was diagnosed with hemiplegic cerebral palsy; the BSID-II test was not performed in this patient because of markedly delayed motor development. There were no significant differences in the BSID-II test results between the 8 infants who received MSCs transplantation and 10 out of 14 infants from the comparison group. One infant in the comparison group had an MDI score <70, indicative of developmental delay (Table III).

We used CAT and CLAMS as additional methods to detect developmental delay. No difference was observed between MSCs and control group infants in the CAT DQ (MSC: 99 ± 4vs comparison: 94 ± 3), and CLAMS DQ (MSC: 97 ± 5 vs comparison: 93 ± 5). Findings of brain MRI obtained at 36-40 weeks of CA and 24 months of CA were not remarkable in 7 of the 8 infants with MSCs transplantation. In an infant (B2 case) with congenital candidiasis, initial MRI performed at 37 weeks CA revealed small cystic encephalomalacia and numerous noncavitary punctate lesions as well as diffuse excessive high signal intensity in the periventricular white matter. These lesions eventually evolved to the typical periventricular leukomalacia with abnormal white matter signal intensity and ventricular margin on follow-up MRI (Figure 3; available at www.jpeds.com).

Discussion

In our previous preclinical translational studies to determine the therapeutic efficacy,9 the optimal route,9,20 dose and timing,13,21 and long-term effects11 of human umbilical cord blood-derived MSCs in the newborn rat hyperoxic lung injury model, the protective effects of MSCs transplantation against neonatal hyperoxic lung injuries consistently showed no long-term toxicity or tumorigenicity.22 In our previous phase I clinical trial,17 intratracheal transplantation of allogenic human umbilical cord blood-derived MSCs in 9 extremely preterm infants at postnatal day 7-14 was well tolerated without any SAEs or dose-limiting toxicity up to 84 days following transplantation, indicating the safety and feasibility of this therapy. Although the long-term safety of MSCs transplantation remains

unknown, in 2 long-term studies in rats up to 70 days11 and 6 months of age,14 comparable with human adolescence and mid-adulthood, respectively, the protective effects of MSCs were persistent and no abnormal gross or histologic findings such as tumors were observed in any of the organs. Wilson et al23 recently reported a phase 1 clinical trial of intravenous MSCs transplantation in 9 adult patients with acute respiratory distress syndrome. In this study, MSCs were infused intravenously and 1 patient was discovered to have embolic infarcts in multiple organs, thought to have occurred prior to the MSC infusion based on MRI results. This study also enrolled high-risk patients with potential risk of death, and reported 2 patients expired within 7 days after MSCs injection, and an additional patient expired after intensive care unit discharge on day 31 after transplantation because of aspiration. In the same study, SAEs associated with MSCs were not observed during 60 days of follow-up after MSC transplantation.23 Furthermore, no adverse outcomes including tumorigenicity have been reported in more than 36 clinical studies of MSCs transplantation conducted worldwide.24 In the present study, although 1 out of the 9 infants died of E cloacae sepsis and the ensuing disseminated intravascular coagulation despite appropriate antibiotic therapy, these SAEs were not judged to be related to MSCs transplantation. No SAE associated with MSCs transplantation including tumorigenicity was observed in the remaining 8 infants up to 24 months of CA. Taken together, these findings support the safety up to 24 months of CA of human intratracheal transplantation of MSCs in preterm infants at high risk for developing BPD. Currently, an extended long-term follow-up study up to 5 years of age (NCT02023788) is underway to assess the long-term safety of the MSCs-transplanted preterm infants from the phase I trial.

Because the infants with BPD can continue to require supplemental oxygen after discharge,25 our data of no home oxygen therapy in the infants who received MSCs transplantation compared with 22% (4/18) of case control infants is encouraging and may indicate reduced BPD severity.17 Other long-term respiratory complications such as wheezing, asthma, or bronchial hyperresponsiveness26 were not observed in this study. Overall, to prove long-term efficacy and further safety, larger phase 2 and 3 trials will be necessary.

In the present study, body weight, height, and head circumference at visit 1 (4-6 months of CA) and were not different between groups. At visit 3 (18-24 months of CA), body weight but not height or head circumference was significantly higher in the MSC group. Our data support that MSCs transplantation may not be harmful and might even be beneficial for later somatic growth. However, our data did not support that higher weight gain in infancy was associated with improved neurodevelopment at 18-24 months of CA. Further studies will be necessary to clarify the associations of later weight gain with better long-term neurodevelopmental outcomes.27

BPD has been identified as an independent risk factor for the development of long-term neurodevelopmental impairments, including cerebral palsy and developmental delays, even in the absence of catastrophic brain injury.28-30 In preclinical studies in newborn rats,31 the intratracheal transplantation of

MSCs simultaneously attenuated both hyperoxic lung and brain injuries, and the extent of neuroprotection was closely linked with that of pulmo-protection. In the present study, no infant who received MSCs transplantation was diagnosed with cerebral palsy or developmental delay, while 1 infant was diagnosed as cerebral palsy and another infant showed BSID-II MDI score of <70 in the comparison group. Overall, these findings suggest that intratracheal transplantation of MSCs in preterm infants at early time points was not detrimental to neurodevelopment. We speculate that improvements in BPD after MSCs transplantation might reduce neurodevelopmental morbidities such as cerebral palsy.3,28-30 The higher weight gain in the infants transplanted with MSCs suggests that these infants may have been overall healthier compared with those in the comparison group during follow-up to 2 years' CA, which would also promote better neurodevelopment.

The promising results observed in the present study provide an important first step toward the safe clinical translation of stem cell therapy for BPD. Safety is suggested by our data; however, considering the major limitations of phase I trials (including small sample size and lack of an appropriate control group), further evaluation is needed. The data collection of historical comparison group was based on the retrospective chart review, so we were unable to collect exact number of readmission or steroid/bronchodilator treatment done in hospitals other than Samsung Medical Center to calculate exact rehospitalization rates or rates of steroid/bronchodilator treatment. Our data warrant further evaluation with double blind randomized phase II/III clinical trials and long-term follow-up of these infants to clarify the safety and efficacy of stem cell therapy for BPD.

In summary, transplantation of MSCs to prevent and/or treat BPD in premature infants at a critical early time point appears safe and potentially effective up to 2 years' CA. This warrants a phase II trial in more infants to further evaluate safety and efficacy. We are currently conducting a phase II clinical trial, as well as long-term follow-up through age 5 years of the infants who completed both the phase I and phase II clinical trials (Clinicaltrials.gov number: NCT02023788). ■

We are grateful to Seungmin Yeon and Sin-Ho Jung for their statistical support.

Submitted for publication Sep 9, 2016; last revision received Dec 30, 2016; accepted Feb 22, 2017

Reprint requests: Won Soon Park, MD, PhD, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Republic of Korea. E-mail: wonspark@skku.edu

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26. Walsh MC, Hibbs AM, Martin CR, Cnaan A, Keller RL, Vittinghoff E, et al. Two-year neurodevelopmental outcomes of ventilated preterm infants treated with inhaled nitric oxide. J Pediatr 2010;156:556-61, e1.

27. Belfort MB, Kuban KC, O'Shea TM, Allred EN, Ehrenkranz RA, Engelke SC, et al. Weight status in the first 2 years of life and neurodevelopmental impairment in extremely low gestational age newborns. J Pediatr 2016;168:30-5, e2.

28. Ratner V, Kishkurno SV, Slinko SK, Sosunov SA, Sosunov AA, Polin RA, et al. The contribution of intermittent hypoxemia to late neurological handicap in mice with hyperoxia-induced lung injury. Neonatology 2007;92:50-8.

29. Anderson PJ, Doyle LW. Neurodevelopmental outcome of bronchopul-monary dysplasia. Semin Perinatol 2006;30:227-32.

30. Dammann O, Leviton A, Bartels DB, Dammann CE. Lung and brain damage in preterm newborns. Are they related? How? Why? Biol Neonate 2004;85:305-13.

31. Kim YE, Park WS, Sung DK, Ahn SY, Sung SI, Yoo HS, et al. Intratra-cheal transplantation of mesenchymal stem cells simultaneously attenuates both lung and brain injuries in hyperoxic newborn rats. Pediatr Res 2016;80:415-24.

Visit 1

Visit 2

1st Nicu CA 4-6 months

Discharge

CA 8-12 months

Visit 3

CA 18-24 months

5 years ongoing

Outpatient clinic Outpatient clinic Outpatient clinic

Neonatology Neonatology Neonatology

Ped Neurology Ped Neurology Ped Neurology

Ped Rehabilitation Ped Rehabilitation Ped Rehabilitation

Ped Opthalmology Ped Otolaryngology

Ped Opthalmology

Growth Growth

Body weight Body weight Growth

Height Height Body weight

Head circumference Head circumference Height

Head circumference

Respiratory Respiratory

outcomes outcomes Respiratory

medication medication outcomes

readmission readmission Medication

Readmission

Development

Cerebral palsy

CAT/CLAMS

Brain MRI

Hearing test

Figure 1. The schedule of follow-up examinations. NICU, neonatal intensive care unit; Ped, pediatric.

CA 37 weeks

CA 24 months

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Figure 3. Brain MRI of B2, who received MSCs transplantation. A, Tl-weighted axial image shows small cyst in the left periventricular leukomalacia (PVL, arrow) and multiple punctate high signal intensity spots in both periventricular white matter. B, Follow-up fluid-attenuated inversion recovery axial image reveals evolution of the punctate white matter lesions into more apparent high signal intensity lesions suggesting astrogliosis. Previously noted cystic encephalomalacia became obliterated, and minimal undulation of the ventricular wall is suggesting periventricular white matter loss.