Fetal and Neonatal Stem Cells

FETAL AND NEONATAL STEM CELLS

Concise Review: Stem Cell Interventions for People With

Cerebral Palsy: Systematic Review With Meta-Analysis
IONA NOVAK,a,b KAREN WALKER,a,c ROD W. HUNT,d,e,f EUAN M. WALLACE,g MICHAEL FAHEY,h
NADIA BADAWIa,c
Key Words. Stem cells x Cerebral palsy x Systematic review x Efficacy x Safety

a
Cerebral Palsy Alliance, The ABSTRACT
University of Sydney, Sydney, Evidence for stem cells as a potential intervention for cerebral palsy is emerging. Our objective was to
New South Wales, Australia; determine the efficacy and safety of stem cells for improving motor and cognitive function of people
b with cerebral palsy. Searches were conducted in October 2015 in CENTRAL, EMBASE, MEDLINE, and
University of Notre Dame
Australia, Fremantle, Cochrane Libraries. Randomized controlled trials and controlled clinical trials of stem cells for cerebral
Western Australia, Australia; palsy were included. Two authors independently decided upon included trials, extracted data, quality,
c
Grace Centre for Newborn and risk of bias. The primary outcome was gross motor function. Secondary outcomes were cognitive
function and adverse events (AEs). Effects were expressed as standardized mean differences (SMD)
Care, Children’s Hospital at
with 95% confidence intervals (CI), using a random-effects model. Five trials comprising 328 partici-
Westmead, The University of pants met inclusion criteria. Four cell types were studied: olfactory ensheathing, neural, neural pro-
Sydney, Sydney, New South genitors, and allogeneic umbilical cord blood (UCBs). Transplantation procedures differed from
Wales, Australia; dNeonatal central nervous system neurosurgical transplantation to intravenous/arterial infusion. Participants
Medicine, The Royal were followed short-term for only 6 months. Evidence of variable quality indicated a small statistically
Children’s Hospital, significant intervention effect from stem cells on gross motor skills (SMD 1.27; 95% CI 0.22, 2.33), with
Melbourne, Victoria, UCBs most effective. There were insufficient and heterogeneous data to compare cognitive effects.
Australia; eNeonatal Serious AEs were rare (n = 4/135 [3%] stem cells; n = 3/139 [2%] controls). Stem cells appeared to
Research, Murdoch Childrens induce short-term improvements in motor skills. Different types of stem cell interventions were com-
Research Institute, pared, meaning the data were heterogeneous and are a study limitation. Further randomized con-
trolled trials are warranted, using rigorous methodologies. STEM CELLS TRANSLATIONAL MEDICINE
Melbourne, Victoria,
2016;5:1014–1025
Australia; fDepartment of
Paediatrics, University of
Melbourne, Melbourne, SIGNIFICANCE
Victoria, Australia; gThe
Ritchie Centre, Department Stem cells are emerging as a scientifically plausible treatment and possible cure for cerebral palsy, but
of Obstetrics are not yet proven. The lack of valid animal models has significantly hampered the scope of clinical
and Gynaecology and trials. Despite the state of current treatment evidence, parents remain optimistic about the potential
h
Department of Paediatrics, improvements from stem cell intervention and feel compelled to exhaust all therapeutic options, in-
Monash University, cluding stem cell tourism. Receiving unproven therapies from unvalidated sources is potentially dan-
Melbourne, Victoria, gerous. Thus it is essential that researchers and clinicians stay up to date. A systematic review and
Australia meta-analysis summarizing and aggregating current research data may provide more conclusive ev-
idence to inform treatment decision making and help direct future research.
Correspondence: Iona Novak,
Ph.D., Head of Research, Cerebral
Palsy Alliance, The University of
Sydney, P.O. Box 6427, French’s INTRODUCTION By definition, individuals with cerebral palsy
Forest, New South Wales 2086, have motor impairments that can be grouped into
Australia. Telephone: Cerebral palsy (CP) is the most common physi- five levels of severity, from ambulatory to wheel-
61 409078917. E-Mail: inovak@ cal disability in childhood, with an incidence of
cerebralpalsy.org.au chair dependent, using the Gross Motor Function
2.1 per 1,000 live births [1]. CP is a lifelong con- Classification System (GMFCS) [4]. However, almost
Received November 30, 2015; dition, and disability increases with age [2]. Care, all individuals experience additional comorbidities,
accepted for publication March 7, loss of income, and tax revenue losses from ce-
2016; published Online First on often leading to additional impairment [5]. For ex-
May 31, 2016. rebral palsy cost the Australian and American ample, among people with cerebral palsy, 3 in 4 are
economies $87 billion per annum [2]. For the in pain, 1 in 2 have an intellectual disability, 1 in 3
©AlphaMed Press
1066-5099/2016/$20.00/0 first time in history, the rate of CP in the devel- cannot walk, 1 in 3 have a hip displacement, 1 in 4
oped world is beginning to decline [3]. Despite cannot talk, 1 in 4 have epilepsy, 1 in 4 have a be-
http://dx.doi.org/
10.5966/sctm.2015-0372 this pleasing progress in the prevention of CP, havior disorder, 1 in 4 have bladder control problems,
for those individuals with CP it remains an incur- 1 in 5 have a sleep disorder, 1 in 5 dribble, 1 in 10 are
able condition. blind, 1 in 15 are tube fed, and 1 in 25 are deaf [6].

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Novak, Walker, Hunt et al. 1015

Description of the Intervention and, in so doing, has limited the scope of patient-based clinical
Numerous rehabilitative and medical interventions exist that help trials [10].
people with cerebral palsy to both develop functional skills in Despite the state of current treatment evidence, parents re-
spite of their permanent physical disability and prevent further main optimistic about the potential improvements from stem cell
physical deterioration from secondary impairments [7]. Despite intervention [13] and many parents are compelled to exhaust all
evidence for the efficacy of rehabilitation and surgical interven- therapeutic options for their child [14], including stem cell tour-
tions for the treatment of comorbidities in people with CP, no sin- ism [13]. Stem cell tourism clinics could be viewed as exploiting
gle medical or rehabilitation treatment currently exists that cures desperate families who have exhausted established medicine
the condition, reduces the severity of the condition, or helps the and rehabilitation interventions and find the wait for stem cells
individual progress upward into a milder GMFCS level. Under- to progress to clinical trials and established therapy too slow
standably, people with cerebral palsy and their families are strong [15]. The safety and efficacy of stem cell treatment and tourism
advocates for urgent research into treatments targeting cure [8]. are not yet clear and apart from the great costs to the family, there
One of their highest-priority research topics (that they identify) is have been several anecdotal reports of serious side effects, in-
the efficacy of stem cells for promoting brain repair [8]. cluding death [16]. Despite this, such clinics often make claims re-
Eminent stem cell scientists and cerebral palsy experts unan- garding the benefits of treatment, without risks disclosed or
imously advised the California Institute for Regenerative Medi- ongoing safety monitoring [15]. Receiving unproven therapies
cine that there was sufficient scientific evidence that “cell from unvalidated sources [15] is potentially dangerous. Thus it
replacement therapies might be particularly effective for cerebral is essential that researchers and clinicians stay up to date with
palsy” [9]. First, because the brain damage in cerebral palsy is of- the outcomes from the numerous registered stem cell clinical tri-
ten “regionally restricted, non-progressive, and appears limited als that aim to cure or treat cerebral palsy. A systematic review
to a few cell types, [thus] stem cell therapy has tremendous po- and meta-analysis summarizing and aggregating current research
tential” [9]. Second, because cerebral palsy involves demyelin- data may provide more conclusive evidence to inform treatment
ation either through primary oligodendrocyte injury or through decision making and help direct future research. This review also
secondary Wallerian degeneration, processes common to other helps to clarify which groups of patients are better suited to these
diagnoses already pioneering stem cell research, “Cell replace- treatments.
ment therapies are exciting eventual options for treating cerebral The objectives are as follows: (a) to assess the efficacy of stem
palsy, and cerebral palsy could be a good testing ground for stem cells (of any type) for improving the motor function of people with
cell replacement in the brain” [9]. cerebral palsy, (b) to assess the efficacy of stem cells (of any type)
The following types of stem cells have been identified for po- for improving the cognitive function of people with cerebral palsy,
tential use in cerebral palsy: amnion epithelial cells (hAECs), and (c) to assess the safety of stem cell transplantation or trans-
CD34-expressing cells from umbilical cord blood, embryonic stem fusion in this group of people.
(ES) cells, fetal stem cells, induced pluripotent stem cells (iPS
cells), mesenchymal stem cells (MSCs), multipotent adult progen-
itor cells (MAPCs), neural stem cells (NSCs), olfactory ensheathing MATERIALS AND METHODS
cells, oligodendrocyte progenitor cells (OPCs), and umbilical cord Criteria for Considering Studies for This Review
blood (UCB)/human UCB [10–12].
Types of Studies, Participants, and Interventions
We included randomized controlled trials (RCTs) and controlled
How the Intervention Might Work trials, with or without blinded outcome assessment, that com-
The mechanisms by which stem cells might treat cerebral palsy pared the outcomes of interventions with stem cells of any type
are proposed to include (a) regenerative mechanisms, replace- versus standard care or no treatment at all or placebo (controls),
ment and/or repair of damaged brain cells brought about by en- in people with cerebral palsy. We included studies of humans with
graftment and proliferation of transplanted cells, which may or cerebral palsy. We did not apply any age, gender, severity of mo-
may not include differentiation of transplanted cells into new tor impairment, or race restrictions. We included comparisons of
microglia or astrocytes to promote reorganization; (b) anti- outcomes after all types of stem cell transplantation or transfu-
inflammatory mechanisms, attenuation of the inflammatory im- sion (allogeneic or autologous) versus standard care or no inter-
mune response to brain injury, via a reduction in the release of vention or placebo (controls).
excitotoxins, cytotoxins, and oxygen free radicals, which if used
early enough might evoke a protective response that reduces
the size and extent of the white matter injury; and (c) trophic
Types of Outcome Measures
mechanisms, to promote cell survival via release of neurotrophic Primary Outcome. Gross motor function was the primary out-
factors secreted from progenitor cells to induce endogenous cell come because physical disability is the chief presenting problem
migration, proliferation, and differentiation and/or to promote in cerebral palsy. Since improvements in motor function from
angiogenesis and new blood vessel formation [10–12]. conventional therapies are small, gains in motor function from
a new therapy may provide a clear advantage.

Why It Is Important to Do This Review Secondary Outcomes. Cognitive function was a secondary out-
Stem cells are emerging as a scientifically plausible treatment and come because half of all children with cerebral palsy have an in-
possible cure for cerebral palsy, but are not yet proven. The lack of tellectual disability, which lowers the likelihood of employment
a valid animal model for such a heterogeneous condition has sig- and independent living plus elevates the risk of premature death
nificantly hampered the translation of laboratory-based research [5]. Rates and types of adverse events were also examined to shed

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1016 Stem Cells for Cerebral Palsy Systematic Review

light on the risk:benefit ratio of stem cell transplantation to in- reporting; and (f) other potential threats to validity. The quality
form patient decision making. of evidence was assessed using the Grades of Recommendation,
Assessment, Development, and Evaluation (GRADE) approach
Search Methods for Identification of Studies [18] and the PEDro Scale, which has established reliability pro-
viding a score out of 10 [19]. Quality ratings allowed objective
Electronic Searches
comparisons of trials. We also summarized study limitations
We developed a search strategy conforming to the recommen- and any imprecision of the evidence that might have affected
dations of the Cochrane Handbook of Systematic Reviews of Inter- the outcomes reported.
ventions [17]. Our comprehensive search used the highly sensitive
search filter for randomized controlled trials [17] to identify both
published and unpublished trials, with no restriction on language Data Synthesis and Measures of Treatment Effect
or study years. Search terms are described in supplemental online Results were presented in a summary of findings table [17]. A
Table 1. priori we planned to perform a meta-analysis. We planned that
The following electronic databases were searched: (a) if two or more included studies had comparable demographics
Cochrane Central Register of Controlled Trials (CENTRAL) (The and outcomes, the mean differences of outcomes would be
Cochrane Library, latest issue), (b) MEDLINE (from 1950 to Octo- pooled using Review manager software (RevMan5), to provide
ber 2015), and (c) EMBASE (from 1950 to October 2015). a summary estimate of a stem cell’s effects. For continuous
outcomes with comparable units, effects were expressed as
Searching Other Resources mean differences with 95% confidence intervals. For continu-
ous outcomes with different units, effects were expressed as
A hand search of the reference list of included studies identified in
standardized mean differences (SMD) with 95% confidence
the electronic searches was also conducted. In addition we elec-
intervals. Analysis was conducted at the individual allocation
tronically and manually searched the conference proceedings of
level because we included studies that used parallel group de-
the American Academy of Cerebral Palsy and Developmental
signs where participants had been randomized (or assigned) to
Medicine, the Australasian Academy of Cerebral Palsy and Devel-
interventions. We assessed heterogeneity of treatment ef-
opmental Medicine, the European Academy of Childhood Disabil-
fects between trials, using chi-square with a significance level
ity, the Pediatric Societies of America, and the International Child
at p , .05. We considered I2 . 25% moderate heterogeneity
Neurology Association Conference to include any gray literature
and I2 . 75% high heterogeneity.
(from 1980 to October 2015). We searched the Internet for infor-
mation on ongoing trials and request information from study in-
vestigators to include within the review, e.g., http://www. RESULTS
clinicaltrials.gov/ (accessed October 15, 2015).
Results of the Search
Data Collection and Analysis Results of the search are reported in a PRISMA flow diagram (Fig.
1) [20]. The initial search was carried out in October 2013 and
Selection of Studies
updated in October 2015. The electronic and hand searches eli-
Two review authors (I.N. and K.W.) independently reviewed the cited 144 references. After screening, 41 studies were potentially
titles and abstracts of studies identified from the aforemen- eligible. After inspecting full texts, 5 studies met eligibility. Rea-
tioned sources. At title and abstract screening we excluded in- sons for exclusion are summarized in the flow diagram. The 5 in-
eligible studies. If the title or the abstract did not provide cluded trials studied 328 participants with cerebral palsy. Studies
sufficient information to determine eligibility, two indepen- meeting inclusion criteria were all published in English. No data
dent reviewers appraised the full texts. We planned that if there were missing and so no contact with authors was needed.
were any disagreements on which articles met inclusion, we
would invite a third reviewer to resolve disagreements. We
planned that where multiple publications were reporting on Included Studies
the same study, only the relevant data would be extracted Types of Study Designs
and included once. We included four RCTs [21–24] plus one nonrandomized clinical
trial (CT) [25] that evaluated the short-term effectiveness of stem
Data Extraction and Management cell intervention for improving the gross motor function of people
Two review authors independently extracted the data with cerebral palsy. Three of the five studies compared stem cells
from the included studies, using the Cochrane methodology with rehabilitation to rehabilitation alone [21, 23, 25]. One trial
[17], extracting citations, methodology, participants, inter- was a three-group RCT comparing (a) stem cells plus erythropoi-
ventions, outcomes, adverse events, and trial limitations. etin plus rehabilitation versus (b) erythropoietin plus rehabilita-
There was agreement on all extracted data. tion versus (c) rehabilitation alone [24], whereas one trial
compared stem cells alone to placebo [22].
Risk of Bias
Two review authors independently assessed risk of bias, using Types of Participants
the Cochrane criteria [17]. There were no disagreements. The All five studies included 100% of participants with the diagnosis of
following methodological attributes were critiqued: (a) se- cerebral palsy. Only one study specified which subtypes of cere-
quence generation; (b) allocation sequence concealment; (c) bral palsy were included [23], which were spastic, dyskinetic, and
blinding of participants, treating clinicians, and outcome asses- mixed. Three of the five studies specified the participant’s gross
sors; (d) incomplete outcome data; (e) selective outcome motor function level at enrollment: all GMFCS levels were

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Novak, Walker, Hunt et al. 1017

End Points
Two of the five trials measured a short-term 1-month after
transplantation/transfusion end point, whereas the other trials
measured at 3–6 months post-transplantation. Only one trial
measured 12-month outcomes. The outcome data at each end
point for each trial are summarized in Table 1. Only one single
common data point existed between the trials (6 months post-
transplantation) and was therefore used in the meta-analysis.

Types of Outcomes Measured

All five trials measured the effect of stem cells on gross motor
function, using the Gross Motor Function Measure (GMFM),
with one trial reporting the data in the alternative Gross Motor
Performance Measure (GMPM) format. The GMFM data were
treated as a continuous variable for analysis.

Effects of Interventions
Effect on Gross Motor
All five trials narratively reported benefits from stem cell inter-
vention on gross motor function, as measured on the GMFM. Four
of five trials reported statistically significant between-group dif-
ferences on GMFM favoring stem cell intervention, but one trial
did not calculate between-group differences [23]. Overall, stem
cells with or without rehabilitation had a greater effect on gross
motor function (as measured on the GMFM) than rehabilitation
alone, SMD = 1.27 [95% CI 0.22–2.33] (Fig. 2A). However, there
was significant heterogeneity between studies (I2 = 92%). In ad-
dition, some trials collected extra motor data before and after
stem cell intervention, including strength measured on the
Figure 1. Flow diagram. manual muscle test [22], fine motor function measured on
the Peabody Developmental Motor Scales (PDMS) [23], and de-
velopmental motor measured on the Bayley Scales of Infant De-
included in Kang and Luan’s studies [22, 23], whereas Chen’s 2013 velopment (Version III) [24]. These data were heterogeneous
study [25] focused on those with more severe physical disability— and could not be pooled.
levels III–V. The age range of participants varied. Three trials stud- Umbilical cord blood was used in two studies and was pooled
ied children less than 12 years old [21, 23, 24], whereas, two trials for separate analysis. Umbilical cord blood, with or without reha-
studied both children and adults simultaneously [22, 25]. bilitation, had a greater effect on gross motor function (as mea-
sured on the GMFM) than rehabilitation alone, SMD = 2.62 [95%
CI 1.51–3.74], but with significant heterogeneity (I2 = 73%). The
Types of Intervention forest plot (Fig. 2B) summarizes the UCB studies.
All five studies aimed to improve the gross motor function using
stem cells plus or minus rehabilitation, allowing meta-analysis. Effect on Cognition
Two studies aimed to improve cognitive function and collected Two studies collected cognitive outcome data [23, 24]. Both sets
cognitive data [22, 24]. The types of stem cells implanted varied of cognitive data had high risk of bias and were of insufficient
and included olfactory ensheathing cells (OECs), NSCs, NPCs, quality for pooling. One trial collected cognitive outcomes on
and allogeneic UCBs. Umbilical cord blood was delivered by an invalidated investigator-designed instrument [23]. The other
both intravenous and intra-arterial transfusion, whereas the trial used the Bayley II rather than the updated Bayley III [24].
OECs, NSCs, and NPCs were neurosurgically transplanted di-
rectly into the central nervous system: either the spine or the Ongoing Studies
brain since OECs, NSCs, and NPCs do not cross the blood–brain
barrier readily. Given the varied cell types and varied doses of We are aware of one ongoing RCT that had completed primary
cells meta-analysis of dose effects was not possible. Type of end-point data collection, which would have met the criteria
cells, origin of cells, dose, transplantation method, and con- for inclusion in this review. Contact was made with the investiga-
comitant use of immunosuppression are summarized in tors but no outcome data were available at the time of writing.
Table 1. The rehabilitation was described with insufficient de- Further information about this study is available at https://
tail to allow replication in future studies. The stem cells used in clinicaltrials.gov/ct2/show/NCT01147653?term=Kurtzberg&rank=3.
the included trials for cerebral palsy, the mechanism of action
[10, 12], the supporting preclinical [10, 12, 26–28] and thera- Risk of Bias in Included Studies
peutic evidence [21–25], and associated risks [10, 12] are sum- The risk of bias in the five included studies was variable and has
marized in Table 2. been summarized in Table 3. Table 3 also includes a summary of

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 Table 1. Summary of findings
1018

Transplant Donor Immuno

Citation Country Method Participants Intervention Cell type Cell dose Cell source method matching suppression Outcomes
Chen et al. China RCT Cerebral palsy Group 1: Stem cell + OECs Single dose 2 3 Allogeneic: Injected into the Yes: None At 6 months:
[21] n = 33 Subtype: Not defined rehabilitation (n = 18) 106 OECs, in 100 Aborted bilateral corona Matching Motor: Improved motor
n = 18 dropouts Severity: Not defined Group 2: ml of medium human fetal radiata in the not on GMFM-66 favoring
Age: 1-12 years Rehabilitation alone olfactory bulb frontal lobe of the described stem cell group (p = .04)
(n = 15) brain Care: No differences
Rehabilitation: between groups for

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Physiotherapy and reduced caregiver
home program, type burden on Caregiver
of physiotherapy not Questionnaire Scale
defined (NS, p = .09)
Chen et al. China Clinical trial, Cerebral palsy Group 1: Stem cell + NSC-like 2 doses, 3 weeks Autologous: Injected into N/A None At 1, 3, 6 months:
[25] nonrandomized Subtype: Not defined rehabilitation (n = 30) apart, 1–2 3 107 Bone marrow subarachnoid Motor: Improved motor
n = 60 Severity: GMFCS Group 2: of NSC-like cells in MSCs cavity of spine at on GMFM-66 favoring
n = 0 dropouts III–V Rehabilitation alone 5-ml cell cultured and L3–L5 stem cell group, 1
Age: 1–32 years (n = 30) suspension propagated in month (NS, p = .09), 3
Rehabilitation: Type vitro until months (p = .01), and 6
not defined differentiated months (p = .01)
into NSCs Language: No
differences between
groups for language on
Gesell LDQ 1 month (NS,
p = .75), 3 months (NS,
p = .52), and 6 months
(NS, p = .30)
Kang et al. South Korea RCT Cerebral palsy Group 1: Stem cell UCB Single dose Allogeneic: Intravenous ,2 HLA i.v. At 1 and 3 months:
[22] n = 36 Subtype: Not defined (n = 17) .2 3 107/kg of Donor UCB infusion and disparities cyclosporine Motor: Improved
n = 2 exclusions Severity: GMFCS I–V Group 2: Placebo UCB from cord Intra-arterial administered muscle strength on
Age: 6.5–20 years (n = 17) blood bank infusion 23/day for 3 manual muscle testing
Rehabilitation: Not days; oral (p , .05).
provided cyclosporine At 6 months:
administered Motor: Improved motor
daily for 9 on GMFM-66 favoring
days; i.v. the stem cell group (p ,
solumedrol .05).
31 dose Those who received a
higher cell dose (which
cannot be controlled
using UCBs) had higher
outcome scores.
Stem Cells for Cerebral Palsy Systematic Review

S TEM C ELLS T RANSLATIONAL M EDICINE

 Table 1. (Cont’d)
Transplant Donor Immuno
Citation Country Method Participants Intervention Cell type Cell dose Cell source method matching suppression Outcomes
Luan et al. China RCT Cerebral palsy Group 1: Stem cell + NPCs Single dose 8–10 Allogeneic: Injected using No None At 1, 6, and 12 months:
[23] n = 94 Subtype: Spastic, rehabilitation (n = 45) 3 106 of NPCs in Aborted ultrasound Motor: Improved motor
dyskinetic, and Group 2: 200 ml normal human fetal guidance into the on GMFM-66 and
mixed Rehabilitation alone saline forebrain lateral ventricles PDMS-FM for stem cell
Severity: GMFCS I–V (n = 49) tissue, of brain through group; however,
Age: 0–3.5 years Rehabilitation: OT cultured and unclosed between-group analysis

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and PT training of propagated fontanelle or burr not provided.
Novak, Walker, Hunt et al.

gross motor, upper for 2–3 weeks hole At 12-months:

extremity function in vitro Improved motor, fine
and activities of daily motor, and cognition
living, plus massage on an
investigator-developed
nonvalidated checklist,
favoring the stem cell
group (p , .001)
Min et al. South Korea RCT Cerebral palsy Group 1: Stem cell + Umbilical Single dose 3 3 Allogeneic: Intravenous Yes: UCB group At 6 months:
[24] n = 105 Subtype: Not defined erythropoietin + cord 107/kg of UCB Donor UCB infusion 4–6/6 HLA received Motor: Improved motor
n = 9 dropouts Severity: Not defined rehabilitation (n = 35) blood from cord match cyclosporine on GMPM (p , .010)
Age: 10 months to Group 2: (UCB) blood bank intravenously and BSID-II Motor scale
10 years Erythropoietin + 23/day for 1 (p , .002) favoring the
rehabilitation + week + oral stem cell group
placebo stem cell cyclosporine Cognition: Improved
(n = 36) for 3 weeks cognition on the BSID-II
Group 3: Mental (p , .008) and
Rehabilitation + the “social cognition”
placebo stem cell + scale in WeeFIM
placebo (p , .013)
erythropoietin
(n = 34)
Rehabilitation: Type
not defined
Abbreviations: BSID, Bayley Scales of Infant Development; GMFM, Gross Motor Function Measure; GMPM, Gross Motor Performance Measure; HLA, human leukocyte antigen; LDQ, Language Developmental
Quotient; MSC, mesenchymal cell; N/A, not applicable; NPC, neural progenitor cell; NS, not significant; NSC, neural stem cell-like; OEC, olfactory ensheathing cell; OT, occupational therapy; PDMS, Peabody
Developmental Motor Scales; PT, physiotherapy; RCT, randomized controlled trial; UCB, umbilical cord blood; WeeFIM = Wee Functional Independence Measure.

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Table 2. Cell types and mechanisms of action, supporting evidence, and associated risks
Assumed mechanism of cell action Preclinical evidence in
Citation Cell types and description for cerebral palsy cerebral palsy Therapeutic evidence in cerebral palsy Associated risks
Chen et al. [21] OECs Mechanism unclear Unknown in cerebral palsy but One included clinical trial [21] Safety in cerebral palsy unknown
Description: OECs are a. Regenerative: OECs ensheathe spinal cord animal model data reported short-term motor gains in Neurosurgical and infection risks exist
macroglia found in the axons in the olfactory receptors, exist children with cerebral palsy but high from the transplantation procedure
nervous system and support and it is hypothesized they might risk of bias existed Tumorigenic risks unknown and

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neurogenesis throughout life have this remyelination action in monitoring should occur using
Source: Adult derived or fetal the brain [21] neuroimaging
derived glial cells from nasal b. Anti-inflammatory: Assumed no
tissue c. Tropic: Assumed yes to promote
tissue sparing and stimulate
endogenous repair [21]
Chen et al. [25] and NSCs and NPCs Mechanisms proposed to include Rodent model: In the neonatal Two included clinical trials [23, 25] Neurosurgical and infection risks exist
Luan et al. [23] Description: NSCs are found in a. Regenerative: NSCs make cerebral palsy stroke model reported short-term motor gains in from the transplantation procedure
the brain and give rise to myelin and it is hypothesized they and hypoxic-ischemic rat children with cerebral palsy but high Tumorigenic risks have not been
neurons, astrocytes, and might remyelinate an injured model NSCs reduce the risk of bias existed observed in phase 1 trials using adult
oligodendrocytes brain or brain with arrested severity of brain injury NSCs with immunosuppression but
Source: Fetal or adult derived myelination from prematurity conferring neurobehavioral safety is unknown for NPCs or NSC-like
adult multipotent cells b. Anti-inflammatory: Assumed no and motor gains [26] cells and therefore monitoring should
c. Tropic: Assumed yes by occur using neuroimaging
stimulating other repair
mechanisms
Kang et al. [22] and UCB Mechanism unclear [10, 12] Rodent model: In the neonatal Two included clinical trials [22, 24] Long-term safety in cerebral palsy
Min et al. [24] Description: UCB contains a. Regenerative: UCBs cannot cerebral palsy stroke model reported short-term motor gains in unknown
hematopoietic stem cells replace damaged brain cells but and hypoxic-ischemic rat people with cerebral palsy from Autologous UCB assumed to be
(HSCs) capable of making all might support regeneration model UCBs reduce the allogeneic UCB transfusion probably safe given the decades of
types of blood cells, but also b. Anti-inflammatory: Assumed severity of brain injury Cerebral palsy clinical trials using long-term safety data in hematologic
comprises a mixture of cells yes given UCB contains MSCs conferring neurobehavioral autologous UCB are under way but applications
including MSCs (see row c. Tropic: Assumed yes since UCBs and motor gains [10, 12] not yet complete Allogeneic UCB appeared relatively
below for more information) home to injured tissue and Sheep model: In the Cerebral palsy clinical trials using safe in the two included clinical trials
and CD34 cells provide paracrine effects that hypoxic-ischemic sheep MSCs are under way but not yet [22, 24] but the theoretical risk of
Source: Adult multipotent might support regeneration model for cerebral palsy, UCB complete graft-versus-host (GVH) disease
cells Mechanism unclear [10, 12] prevents neuronal apoptosis Comment: MSCs are more likely to be exists, even though GVH is considered
MSCs a. Regenerative: MSCs cannot [27] helpful for infants with cerebral palsy unlikely to occur in people with
Description: Bone marrow replace damaged brain cells but Rodent model: In the neonatal during the early acute and cerebral palsy with healthy immune
stromal cells, composed of a might support regeneration cerebral palsy stroke model, inflammatory brain injury phase, systems
mixture of cell types b. Anti-inflammatory: Assumed intranasal delivery of MSCs e.g., in neonatal stroke and Long-term safety in cerebral palsy is
Source: Adult multipotent yes significantly reduces infarct hypoxic-ischemic encephalopathy unknown
cells c. Tropic: Assumed yes since MSCs size and gray matter loss [28] causal pathways to cerebral palsy Assumed to be low risk because they
Comment: Umbilical cord home to injured tissue and Primate model: MSCs have historically been assumed to be
blood contains MSCs provide paracrine effects that transplantation leads to immune privileged, although this
might support regeneration, e.g., upregulation of IL-10 knowledge is evolving
by sparing intrinsic cells and expression, plus a decrease in
secretion of growth factors that neuronal apoptosis and
stimulate repair processes astroglial activity in the
periischemic area [10]
Abbreviations: MSC, mesenchymal stem cell; NPC, neural progenitor cell; NSC, neural stem cell-like; OEC, olfactory ensheathing cell; UCB, umbilical cord blood.
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Novak, Walker, Hunt et al. 1021

Figure 2. Forest plot. Abbreviation: CI, confidence interval.

the quality ratings of the included studies and the trial limitations. rehabilitation or placebo. In addition, we wanted to review
The two trials using umbilical cord blood, from the same South the safety of stem cell intervention by reviewing the numbers
Korean research group, used high-quality methodologies and of adverse events. There were five trials (four RCTs and one
had low risk of bias [22, 24]. nonrandomized trial) of stem cell interventions for people with
cerebral palsy included in the review, with all studies providing
Adverse Events sufficient data to be included in the primary outcome of the
meta-analysis about gross motor effects. Meta-analysis dem-
Serious adverse events associated with stem cell transplanta- onstrated a positive short-term treatment effect for stem cell
tion were reported from two of the five included trials [23, intervention on gross motor outcomes measured on the Gross
24]. In two of the five trials, the details about adverse events Motor Function Measure. It is difficult to determine whether
were scant and considered insufficient, given the potential risks the size of the effect is of clinical significance because of the
[21, 25]. Neuroimaging was not performed in the trials where wide age ranges of the participants studied. Larger effect sizes
invasive stem cell transplantation techniques were used [21, are possible, expected, and needed in younger children for the
23, 25], and untoward adverse effects, like tumor growth, were result to be clinically meaningful, since their gross motor skills
therefore not adequately monitored. Adverse event details rapidly develop in childhood. Yet in the included studies, young
were most comprehensively reported in the Kang [22] and children and adults were included within the same samples.
Min [24] trials. A summary of the rates of serious adverse events The methodological decision to group children more than 5
for each trial is described in Table 4. Serious adverse events in- years old with adults and compare this to children under 5
cluded death of one participant in the stem cell group of Min’s years old may have confounded study findings, since children’s
trial. The cause of death was unknown. Of note, the participant gross motor potential plateaus after 5 years of age [29] and it
had a seizure 24 hours prior to death, plus the family had not would be reasonable to expect their capability to respond to
implemented the recommended nonoral feeding intervention. this type of intervention might be different. Moreover, from
The other n = 6 serious adverse events (AEs) recorded across a regenerative medicine perspective, it would be reasonable
all five trials were equally distributed across the stem cell and to expect better intervention responses from participants
control groups. Fever was a nonserious adverse event that oc- whose age was closer to the timing of the injury. Future studies
curred equally across groups. should carefully consider gender and age at transfusion/
transplantation as covariates and ultimately aim to treat youn-
ger patients.
DISCUSSION
An earlier systematic review investigated the effectiveness of
The objectives of this systematic review were to determine stem cell intervention for people with cerebral palsy and con-
the effect of stem cell intervention for people with cerebral cluded that “There were very few well-designed controlled
palsy on gross motor and cognitive function compared with clinical studies. There is a need for well-designed controlled

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Table 3. Risk of bias, methodological quality, and trial limitations

Random sequence Allocation Blinding of participants Blinding of outcome Incomplete Selective PEDro GRADE
generation: concealment: and personnel: assessment: outcome data: reporting: trial quality quality
Citation selection bias selection bias performance bias detection bias attrition bias reporting bias score rating Study limitations
Chen et al. Low risk Low risk Unclear risk Unclear risk High risk High risk 5/10 Low Sample: Large number of dropouts (n = 18/33); n = 7/33 of

©AlphaMed Press 2016

[21] intended sample not recruited; wide age range studied
Design and analysis: Small sample size
Chen et al. High risk High risk High risk Low risk Low risk Low risk 5/10 Low Design and analysis: Lack of randomization; small sample size
[25] Instruments: Validlity of Gessell data collected in children too
old for the instrument; redundancy of collecting the
GMFM-88 data, when GMFM-66 also collected
Kang et al. Low risk Low risk Low risk Low risk Unclear risk Low risk 8/10 High Sample: Wide age range studied; placebo group median age
[22] is older and therefore may be less responsive to any
intervention; unclear why n = 2 participants were excluded
after randomization
Design and analysis: Lack of rehabilitation protocol for both
arms of the trial, when rehabilitation is standard of care (i.e.,
patients could have been worsening by natural history)
Instruments: Manual muscle test validity in (a) 6-month-old
children who cannot respond to commands and (b) people
without the selective motor control to complete testing;
validly of Bayley II, PEDI, weeFIM data collected in children
and adults too old for the instrument’s upper age range; use
of Bayley II, not Bayley III
Intervention: Use of i.v. and i.a. infusion in the same study,
resulting in some data needing to be excluded; confounding
use of cyclosporine as an immunosuppressant, since
cyclosporine might also have neuroprotective effects
Luan et al. Unclear risk Unclear risk Unclear risk Low risk Low risk High risk 6/10 Moderate Design and analysis: Not stated if participants were blinded;
[23] no between-group analysis conducted for standardized
measures
Instruments: Use of an author-devised cognitive assessment
test, which had unknown psychometric properties
Min et al. Unclear risk Low risk Low risk Low risk Low risk Low risk 9/10 High Design and analysis: Lack of a UCB + rehabilitation group to
[24] allow examination of the effects of UCB; random sequence
generation not described
Instruments: Validly of Bayley II, PEDI, weeFIM data collected
in children and adults too old for the instrument’s upper age
range; use of Bayley II, not Bayley III
Intervention: Confounding use of cyclosporine as an
immunosuppressant, since cyclosporine might also have
neuroprotective effects
Abbreviations: GMFM, Gross Motor Function Measure; PEDI, Pediatric Evaluation of Disability Inventory; UCB, umbilical cord blood; WeeFIM = Wee Functional Independence Measure.
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Table 4. Rates of serious adverse events

Serious adverse events
Citation Event Stem cell Rehabilitation Erythropoietin
Chen et al. [21] Death 0/6 0/8 N/A
Other serious adverse event 0/6 0/8 N/A
Total (%) 0/6 (0) 0/8 (0) N/A
Chen et al. [25] Death 0/30 0/30 N/A
Other serious adverse event 0/30 0/30 N/A
Total (%) 0/30 (0) 0/30 (0) N/A
Kang et al. [22] Death 0/18 0/18 N/A
Other serious adverse event 0/18 0/18 N/A
Total (%) 0/18 (0) 0/18 (0) N/A
Luan et al. [23] Death 0/45 0/49 N/A
Other serious adverse event 1/45 0/49 N/A
Total (%) 1/45 (2) 0/49 (0) N/A
Min et al. [24] Death 1/35 0/34 0/34
Other serious adverse event 2/35 3/34 3/34
Total (%) 3/36 (8) 3/34 (9) 3/36 (8)
Total (%) 4/135 (3) 3/139 (2) 3/36 (8)
Abbreviation: N/A, not applicable.

studies with more objective outcome measures” [30]. Dartnell’s in both groups, but since fever can escalate to a serious health
[30] systematic review, however, did not include all the high-level risk, monitoring after transplantation and transfusion is advised in
evidence clinical trials we identified in our comprehensive search future trials.
nor did it include a meta-analysis and therefore our update was
warranted. To our knowledge, this is the first meta-analysis of
stem cell interventions for people with cerebral palsy. CONCLUSION
Our review and meta-analysis have a number of limitations Our meta-analysis demonstrated that stem cell interventions for
concerning stem cell intervention. The experimental stem cell people with cerebral palsy have a small but significant short-term
interventions in this review varied in terms of the types and impact on gross motor skills. Stem cell intervention is not yet a cure,
ages of participants that received intervention, the types of but has a larger treatment effect than rehabilitation alone. Rehabil-
cells used, the types of transplant/transfusion methods used, itation, pharmacology, and orthopedic surgery are the current stan-
the cell doses, the theoretical rationale for why the cells might dard of care. The rate of serious adverse events reported in these
offer a treatment effect, the type and intensity of concomitant trials was low (3% stem cells, 2% controls), suggesting an acceptable
rehabilitation, and the duration of follow-up. This resulted in benefit:risk ratio. Further and longer-duration studies are therefore
significant levels of heterogeneity when pooling gross motor advisable to determine whether stem cell interventions might be an
outcomes and, therefore, limits the conclusions that can be additive intervention that could be included within the cocktail of
drawn from these results. In addition, the studies measured interventions that compose standard care.
only short-term benefits and the long-term effects remain
unknown.
Different cognitive measurement tools were used in the stud- Implications for Research
ies, restricting the ability to pool data. It is possible either that The result of the meta-analysis indicates that more stem cell re-
these studies have no effect on cognitive outcome or that the search for cerebral palsy is worthwhile. Future clinical trials
measures did detect the effects of intervention but our interpre- evaluating the effectiveness of stem cell intervention for cere-
tation of the meaning of these gains is cautious given the high risk bral palsy should use high-quality designs, sensitive measures,
of bias. There were fewer measurement tools used for assessing larger samples, and younger and more homogeneous pa-
gross motor change than those used for assessing cognitive tients closer to the timing of injury when considering age of
change, which made it possible to pool the motor data for transfusion/transplantation; measure whether gender affects
meta-analysis. outcomes; use well-matched allogeneic donor cells, noncon-
The combined AE results conservatively suggest statistically founding or no immunosuppression drugs, and more tightly
comparable risks between groups (3% in the stem cell groups, controlled rehabilitation; measure long-term impact; and con-
2% in the rehabilitation groups). Given the concern of the risks, sider tractography as one outcome as well as neuroimaging to
continued safety monitoring post-transplantation or -transfusion is detect adverse events. Future cerebral palsy stem cell research
advised. All future trials should include detailed adverse event studies should focus on mechanisms with supporting preclinical
logs such as the one provided by Min et al. [24] and neuroimag- data, and human studies should be designed using the SPIRIT
ing when invasive transplantation techniques are used. The statement [31] and reported according to the CONSORT state-
cause of the one death was unknown. Fever equally occurred ment [32]. We have summarized cerebral palsy stem cell

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1024 Stem Cells for Cerebral Palsy Systematic Review

Figure 3. Recommendations for future research.

research progress to date and our recommendations for the of manuscript; R.W.H., E.M.W., M.F., N.B.: critical review and revi-
field going forward in Figure 3. sion of manuscript, final approval of manuscript.

ACKNOWLEDGMENTS
DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST
All authors approved the final manuscript as submitted and agree
to be accountable for all aspects of the work. R.W.H. has compensated research funding from a project grant from
the National Health and Medical Research Council (NHMRC) for study
investigating the utility of amplitude-integrated electroencephalogra-
AUTHOR CONTRIBUTIONS
phy (aEEG) in the management of electrographic seizures. M.F. has
I.N.: conception and design, initial manuscript writing, data extrac- compensated research funding from Umbilical Cord Blood (UCB) Clin-
tion, analyses, final approval of manuscript; K.W.: data extraction, ical Trials and compensated stock options from Sigma Pharmaceuti-
critical analyses, review and revision of manuscript, final approval cals. The other authors indicated no potential conflicts of interest.

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