www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2 1
Embryonic stem cell trials for macular degeneration:
a preliminary report
Steven D Schwartz, Jean-Pierre Hubschman, Gad Heilwell, Valentina Franco-Cardenas, Carolyn K Pan, Rosaleen M Ostrick, Edmund Mickunas,
Roger Gay, Irina Klimanskaya, Robert Lanza
Background It has been 13 years since the discovery of human embryonic stem cells (hESCs). Our report provides the
first description of hESC-derived cells transplanted into human patients.
Methods We started two prospective clinical studies to establish the safety and tolerability of subretinal transplantation
of hESC-derived retinal pigment epithelium (RPE) in patients with Stargardt’s macular dystrophy and dry age-related
macular degeneration—the leading cause of blindness in the developed world. Preoperative and postoperative
ophthalmic examinations included visual acuity, fluorescein angiography, optical coherence tomography, and visual
field testing. These studies are registered with ClinicalTrials.gov, numbers NCT01345006 and NCT01344993.
Findings Controlled hESC differentiation resulted in greater than 99% pure RPE. The cells displayed typical RPE
behaviour and integrated into the host RPE layer forming mature quiescent monolayers after trans plantation in
animals. The stage of differentiation substantially affected attachment and survival of the cells in vitro after clinical
formulation. Lightly pigmented cells attached and spread in a substantially greater proportion (>90%) than more
darkly pigmented cells after culture. After surgery, structural evidence confirmed cells had attached and continued to
persist during our study. We did not identify signs of hyperproliferation, abnormal growth, or immune mediated
transplant rejection in either patient during the first 4 months. Although there is little agreement between investigators
on visual endpoints in patients with low vision, it is encouraging that during the observation period neither patient
lost vision. Best corrected visual acuity improved from hand motions to 20/800 (and improved from 0 to 5 letters on
the Early Treatment Diabetic Retinopathy Study [ETDRS] visual acuity chart) in the study eye of the patient with
Stargardt’s macular dystrophy, and vision also seemed to improve in the patient with dry age-related macular
degeneration (from 21 ETDRS letters to 28).
Interpretation The hESC-derived RPE cells showed no signs of hyperproliferation, tumorigenicity, ectopic tissue
formation, or apparent rejection after 4 months. The future therapeutic goal will be to treat patients earlier in the
disease processes, potentially increasing the likelihood of photoreceptor and central visual rescue.
Funding Advanced Cell Technology.
Since their discovery in 1998,1 human embryonic stem
cells (hESCs) have been thought a promising source of
replacement cells for regenerative medicine. Despite great
scientific progress, hESCs are among the most complex
biological therapeutic entities proposed for clinical use.2 In
addition to the dynamic complexity of their biology, many
regulatory concerns have hindered clinical translation,
including the risk of teratoma formation and the challenges
associated with histo incompatibility. Until reprogramming
technologies, such as somatic-cell nuclear transfer3 or
induced pluripotent stem cells,4,5 are further developed,
diseases affecting the eye and other immunoprivileged
sites will probably be the first pluripotent stem cell-based
therapies in patients. It is well established that the
subretinal space is protected by a blood–ocular barrier, and
is characterised by antigen-specific inhibition of both the
cellular and humoral immune responses.6
In the retina, degeneration of the retinal pigment
epithelium (RPE) leads to photoreceptor loss in many
sight-threatening diseases, including dry age-related
macular degeneration and Stargardt’s macular dystrophy.
Dry age-related macular degeneration is the leading
cause of blindness in the developed world, and Stargardt’s
macular dystrophy is the most common paediatric
macular degeneration. Although both are untreatable at
present, there is evidence in models of macular
degeneration in mice and rats that transplantation of
hESC-derived RPE can rescue photoreceptors and prevent
loss of vision.7,8 Among its functions, the RPE maintains
the health of photoreceptors by recycling photopigments,
metabolising vitamin A, and phago cytosing photoreceptor
outer segments.9,10 In studies in the Royal College of
Surgeons (RCS) rat, an animal model in which vision
deteriorates because of RPE dysfunction, subretinal
transplantation of hESC-derived RPE resulted in
extensive photoreceptor rescue and improvement in
vision without evidence of untoward pathological effects.7
These and other safety studies8 suggest that hESCs could
serve as a potentially safe and inexhaustible source of
RPE for the efficacious treatment of many retinal
January 23, 2012
Jules Stein Eye Institute Retina
Division, Department of
Ophthalmology, David Geffen
School of Medicine, University
of California, Los Angeles, CA,
USA (Prof S D Schwartz MD,
J-P Hubschman MD,
G Heilwell MD,
V Franco-Cardenas MD,
C K Pan MD, R M Ostrick MPH);
and Advanced Cell Technology,
Marlborough, MA, USA
(E Mickunas MS, R Gay PhD,
I Klimanskaya PhD, R Lanza MD)
Prof Steven D Schwartz,
Ahmanson Professor of
Ophthalmology, Chief, Retina
Division, Jules Stein Eye Institute,
Los Angeles, CA 90095, USA
Dr Robert Lanza, Chief Scientific
Officer, Advanced Cell
MA 01752, USA
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2
Transplantation of intact sheets and suspensions of
primary RPE cells has been previously attempted in
people, with mixed results; both in terms of graft survival
and improvement in vision.11–18 However, there are
advantages to the use of progeny obtained from hESCs
as a source of replacement tissue for clinical studies. In
addition to producing an unlimited number of healthy
young cells with potentially reduced immunogenicity,19,20
the stage of in-vitro differentiation can be controlled to
ensure optimum safety, identity, purity, and potency
before transplantation into the targeted population of
patients. The hESC derivatives must be free of patho-
gens, possess the appropriate characteristics of the
differentiated cell, be of high purity, and free of
undifferentiated cells. They must also be extensively
tested in animals for absence of teratomas, migration of
cells into other organs, and adverse effects. The goal of
our studies was to assess the safety and tolerability of
hESC-derived RPE cells, including teratoma formation,
hyperproliferation of the cells, ectopic tissue formation,
and immune rejection. We report our preliminary
experience with two patients: one with dry age-related
macular degeneration and one with Stargardt’s disease.
We selected patients on the basis of several inclusion
and exclusion criteria (webappendix), including end-
stage disease, central visual loss, the absence of other
clinically significant ophthalmic pathological effects,
a cancer-free medical history, present cancer screening,
the absence of contraindications for systemic immuno-
suppression, the ability to undergo a vitreoretinal
surgical procedure under monitored anaesthesia care,
and psychological suitability to participate in a first-in-
human clinical trial involving hESC-derived transplant
tissue. Patients provided written informed consent and
ethical approval was obtained from the University of
California, Los Angeles, institutional review board.
We used hESC line MA09 cells21 to generate a master cell
bank with Good Manufacturing Practices; this cell line
has ex-vivo exposure with mouse embryo cells and is
thus classified as a xenotransplantation product. The
hESC master cell bank was thawed and expanded on
mitomycin-C-treated mouse embryonic fibroblasts for
three passages. After embryoid body formation and
cellular outgrowth, we isolated pigmented RPE patches8
with collagenase. After purification and trypsinisation,
the cells were expanded and cryopreserved at passage
2 for clinical use. We characterised RPE in-process and
after freezing and formulation, including karyo typing,
pathogen and phagocytosis assay testing, and differen-
tiation and purity evaluation by morpho logical
assessment, quantitative PCR, and quantitative immuno-
staining for RPE and hESC markers (webappendix).
In preclinical studies we injected hESC-RPE subretinally
into National Institutes of Health (NIH) III immune-
nude mice (tumorigenicity and biodistribution studies),
and dystrophic RCS rats and ELOVL4 mice (efficacy
studies) as described elsewhere.8 To detect human cells
in the injected eyes and other organs, we used DNA
quantitative PCR, designed to amplify human Alu Y
DNA sequences, and immuno staining of paraffin
sections for human mitochondria and human bestrophin
For clinical studies we thawed, washed, and
resuspended vials of cryopreserved MA09-RPE at a
density of 2×10³ viable cells per µL of BSS Plus
(Alcon, Hünenberg, Switzerland). A vial containing the
appropriate volume of formulated RPE and a paired vial
containing the appropriate volume of BSS Plus at 2–8°C
were delivered to the operating room. Immediately before
injection, the two vials were reconstituted in a 1 mL
syringe to obtain the targeted injection density of
333 viable RPE cells per µl. 150 µL of reconstituted
RPE was injected through a MedOne PolyTip cannula
25/38 delivering the targeted dose of 50 000 viable RPE
cells into the subretinal space of each patient’s eye.
We did pars plana vitrectomy including surgical
induction of posterior vitreous separation from the optic
nerve anteriorly to the posterior border of the vitreous
base. Submacular injection of 5×10⁴ hESC-RPE cells in
150 µL was delivered into a preselected region of the
pericentral macula that was not completely lost to disease.
We carefully chose transplantation sites on the basis of
optical coherence tomographic data suggesting the
presence of native, albeit compromised, RPE and
similarly compromised overlying photoreceptors, to
optimise the chances of transplant integration and
potential for photoreceptor-cell rescue. We thought trans-
plant engraftment within a completely atrophic central
macula was unlikely in view of the loss of Bruch’s
membrane in advanced atrophic disease.22 Further,
complete macular atrophy does not mimic central
macular status in earlier stages of degeneration, which
might be the ultimate therapeutic target of a stem-cell-
based regenerative transplant strategy.
The immunosuppression regimen included low-dose
tacrolimus (target blood concentrations 3–7 ng/mL)
and mycophenolate mofetil (ranging from 0·25 to
2·00 g orally per day) a week before the surgical
procedure and continued for 6 weeks. At week 6, the
regimen calls for discontinuation of tacrolimus and
a continuation of mycophenolate mofetil for an
additional 6 weeks. These studies are registered
with ClinicalTrials.gov, numbers NCT01345006 and
Role of the funding source
The sponsor of the study participated in study design,
data collection, data analysis, data interpretation, and
writing of the report. The corresponding authors had full
See Online for webappendix
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2 3
access to all the data in the study and had final
responsibility for the decision to submit for publication.
Controlled hESC differentiation resulted in greater than
99% pure RPE (figure 1). A single six-well plate of
pigmented patches produced about 1·5×10⁸ RPE cells
(sufficient to treat >50 patients). The cells displayed typical
RPE behaviour, losing their pigmented cobblestone
morphology during proliferation and redifferentiating
into a monolayer of polygonal cuboidal pigmented
epithelium once confluence was established. Quantitative
PCR showed that markers of pluripotency (OCT4,
NANOG, and SOX2) were substantially downregulated,
whereas the transient marker of neuroectoderm differen-
tiation, PAX6, and RPE markers, RPE65, bestrophin, and
MITF, were expressed at high levels (web appendix). In
mature cultures greater than 99% of the cells were
positive for ZO-1 and bestrophin, PAX6, or both (PAX6
disappearing in more mature cells). After cryo preserva-
tion, cells were thawed and formulated for transplantation.
Staining for PAX6, MITF, or both (figure 1) was done on
formulated RPE cultured overnight, confirming greater
than 99% RPE purity. After further culture PAX6/
bestrophin and ZO-1 immunostaining was similar to
preharvest cultures, and a potency assay showed greater
than 85% of the cells phagocytosed bioparticles
Since the hESCs were exposed to animal cells, the
master cell bank and RPE were extensively tested for
animal and human pathogens. We confirmed the cells
were free of microbial contaminants, including animal
13 14 1516 1718
6789 1011 12
Log up or down regulation
Reference RPE lot
Clinical RPE lot
Total cell fluorescence (FL2-area)
Figure 1: Characterisation of RPE generated from hESC-MA09 cells
A six-well plate with pigmented patches of RPE formed in differentiating culture of embryoid bodies (A) and assessment of molecular markers in thawed and formulated RPE (B–H). (B) Hoffman
modulation contrast microphotography of 3-week-old RPE after formulation showing that the confluent cobblestone monolayer with medium pigmentation has been established. (C) MITF/PAX6
merged (MITF=red, PAX6=green). (D) DAPI corresponding to MITF/PAX6. (E) Bestrophin (red)/PAX6 (green) merged. (F) Corresponding DAPI. (G) ZO-1. (H) Corresponding DAPI. Note that near 100%
of cells in C–H are positive for the marker(s) assessed. Magnification ×400 (B–H). (I) Quantitative PCR showing up-regulation of RPE markers and down-regulation of hESC markers in the thawed
clinical RPE compared with a reference RPE lot. (J) Flow cytometry histogram showing phagocytosis of PhRodo bioparticles by hES-RPE at 37°C and at 4°C (control). (K) normal female (46 XX)
karyotype of the clinical RPE lot. MITF and PAX6 (C, D) were assessed in overnight cultures of freshly formulated cells and bestrophin/PAX6 and ZO-1 immunostaining was done on 3-week-old cultures.
Quantitative immunohistochemical staining was done with standard methods with the percentage of positive stained cells normalised to the number of DAPI stained nuclei inspected. Assessment of
RPE purity and the extent of differentiation were based on the percentage of bestrophin, PAX6, ZO-1, and MITF stained cells. RPE=retinal pigment epithelium. hESC=human embryonic stem cells.
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2
and human viral pathogens (webappendix). The final
RPE product had normal female (46 XX) karyotype
(figure 1); a high sensitivity assay ruled out the
presence of contaminating hESCs: examination of
2 million/9 million cell RPE samples (at P1/P2) stained
for OCT4 and alkaline phosphatase showed no presence
of pluripotent cells. Tumorigenicity, biodistri bution, and
spiking studies done in NIH III mice showed no adverse
or safety issues in any animals. Additionally, we did not
identify tumours in animals injected with 5–10×10⁴ RPE
cells spiked with either 0·01%, 0·1%, or 1% un-
differentiated hESCs, whereas undifferentiated hESCs
developed teratomas by 2 months in all animals. Survival
of hRPE was confirmed in the eyes of all the animals up
to 3 months after injection, and in 48 (92%) of the
52 animals at 9 months (webappendix). hRPE survived
for the lifetime of the animals and integrated into the
mouse RPE layer; although morphologically indiscernible
from the host RPE (figure 2), they could be identified by
immuno staining and expressed bestrophin in a typical
basolateral fashion. Ki-67 staining showed a low level of
proliferation 1–3 months after transplantation, but we
did not identify Ki-67-positive cells at 9 months, sug-
gesting that the hESC-RPE had formed quiescent
We harvested two lots of RPE at different levels of
pigmentation (melanin content was 4·8 pg per cell
[SD 0·3] for the lighter pigmented lots and 10·4 [SD 0·9]
for the more heavily pigmented lots). We processed cells
from both lots with the protocol for clinical transplantation
described in the Methods section. After extrusion through
the injection cannula, we seeded the cells onto gelatin-
coated plates and monitored for attachment and
subsequent growth. RPE from the lighter pigmented lot
showed a minimal number of floating cells in overnight
cultures; most of the cells had attached and spread,
displaying typical RPE morphology for this stage of
growth (figure 3). After 3 days in culture, the number of
lighter pigmented cells had increased from 4·0×10⁴ to
10·6×10⁴ cells (figure 3). By contrast, the heavily
pigmented RPE had large numbers of floating cells; only
a small proportion of the cells attached and survived,
with a substantially decreased number of cells (<10%
[9·0×10³] noted in the lighter lot) after 3 days in culture
(figure 3). These results suggest a strong correlation
between the stage of RPE differentiation and the ability
to adhere and thrive in vitro. The RPE lot we used had a
melanin content of 4·1 pg per cell with similar attachment
and growth to the lighter lot. Stresses associated with
the freeze–thaw cycle, washings, centrifugation, and
extrusion through the injection cannula might account
in part for the recorded differences between lightly and
heavily pigmented cells.
We did not identify any hyperproliferation or abnormal
growth in either patient at any point during the follow-
up period when assessed by detailed biomicroscopic and
indirect ophthalmoscopic clinical examinations at
multiple postoperative assessments. Absence of teratoma
formation was confirmed with laboratory studies
including spectral domain optical coherence tomography,
high resolution digital fundus photography, autofluores-
cence imaging, and fluorescein angiography studies
done serially throughout the follow-up period.
Neither patient studied had hESC-RPE proliferation
outside the subretinal space on clinical examination or
laboratory testing. After extensive scanning of the
preretinal space of both patients with spectral domain
ocular coherence tomography, we detected a single
pigmented cell on the retinal surface of the patient
with Stargardt’s macular dystrophy. This cell is near
the retinotomy site and has not shown any sign of
proliferation or contraction.
At no point after transplantation did we detect any
signs of intraocular inflammation or hyperproliferation
in either patient. Absence of clinically detectable
inflam mation was corroborated with slit lamp
Photoreceptor cells Photoreceptor cells
Figure 2: Survival and integration of RPE generated from hESC-MA09 into an NIH III mouse eye after 9 months
Section stained with anti-human mitochondria (A) and anti-human bestrophin (B). Note the precise colocalisation
of human mitochondria and bestrophin staining in the same cells (C; A and B merged) and absence of staining in
mouse RPE (F; A, B, C, and E merged). Frame on the bright field image (E) is enlarged in D to show morphology of
human RPE. Magnification ×200 (A–C, E, and F), D is additionally magnified ×4·5. RPE=retinal pigment epithelium.
hESC=human embryonic stem cells. NIH=National Institutes of Health.
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2 5
biomicroscopic photography, fundus photography,
intravenous fluor escein angiography, and spectral
domain ocular coherence tomography (webappendix).
Both operated eyes were free of inflammation throughout
the post operative period. Indeed, we did not detect any
signs of clinically significant intraocular inflammation
related safety signals such as uveitis, cataract, macular
oedema, secondary glaucoma, rises in intraocular
pressure, serous retinal detachment, pain, or photophobia.
Both eyes studied had an uneventful postoperative
surgical course with mild conjunctival haemorrhage and
hyperaemia resolving within the first postoperative week.
Both patients were comfortable during the postoperative
period and tolerated the procedures well. Neither patient
needed postoperative analgesia.
A secondary concern is whether the subretinal bleb
created by the transplant injection might lead to retinal
detachment. We noted 100% flattening of the surgical
bleb in both patients at 4 h after transplantation. At no
point did we detect retinal detachment or any lesion
predisposing to retinal detachment in either eye studied.
evidence of hESC-RPE has been difficult to confirm in
the patient with dry age-related macular degeneration.
On postoperative day 1, the bed of the transplant bleb
seemed to be hyperpigmented on biomicroscopic
examination. However, on subsequent serial assessments
we could not confirm clinically detectable hyper pigment-
ation. During the first post operative week, the patient
with age-related macular degeneration did not comply
with the immunosuppression regimen and blood
concentrations of the agents dropped below the
We noted anatomical evidence of hESC-RPE survival
and engraftment in the patient with Stargardt’s macular
dystrophy. We detected clinically increased pigmentation
at the level of the RPE within the bed of the transplant
beginning at postoperative week 1 to month 3 (figure 4).
The transplanted cells seem to have involved regions of
complete pretransplant RPE loss as well as regions
of pretransplant RPE compromise (figure 4). Spectral
domain ocular coherence tomograph images collected at
postoperative month 3 show survival and engraftment
of hESC-RPE. Our findings confirm the recorded
morphological RPE features of the pigmentation, and
localise the transplanted cells to precisely the desired
We recorded functional visual improvements in both
patients. Despite the lack of anatomical evidence, the
patient with macular degeneration had functional
improvements that included best corrected visual acuity
changes from 21 Early Treatment Diabetic Retinopathy
Study (ETDRS) letters (20/500) at baseline to 33 ETDRS
letters (20/200) at week 2. By week 6 she was reading
28 ETDRS letters (20/320) and has remained stable at
this level through postoperative month 3. Goldman visual
fields done by an experienced certified examiner (from
Cell number per well
Days in culture
Figure 3: Difference in attachment and growth of RPE with different degrees of pigmentation
RPE from two lots were thawed, formulated, extruded through the injection cannula, and subsequently plated in
cell culture medium on gelatin-coated plates. Micrographs show attachment and behaviour of cells from a lighter
(A, C, E) and a darker (B, D, F) pigmented lot. A and B show the total cell population at 21 h after plating. The
number of flat and adhering cells is an indication of relative plating efficiency. Note that most cells in the lighter
pigmented lot (A) have attached, whereas most cells in the darker lot (B) remain rounded and unattached. C and D
show the same cultures as A and B after removal of floating cells (arrows show flat adherent cells). E and F show the
same cultures 3 days after plating. The lighter pigmented lot (E) has a greater number of cells and a confluent
monolayer is established, whereas the darker lot (F) is still under confluent. Magnification ×200. G illustrates the
growth of RPE cells from both lots showing the total cell number per well on 3 consecutive days after plating. On the
indicated day, cells were trypsinised and counted in a haemocytometer. Data are the mean cell number ± SD of cell
counts done on triplicate wells. RPE=retinal pigment epithelium.
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2
whom the treatment was not masked) showed no
diminution of visual field; this could reasonably be
interpreted as improved vision (preoperative and
postoperative fields are shown in the webappendix).
Confounding these apparent functional gains in the
study eye, we also detected mild visual function increases
in the fellow eye of the patient with age-related macular
degeneration during the postoperative period.
We noted clear functional visual improvement in the
study eye of the patient with Stargardt’s macular
dystrophy corresponding subjectively to the transplanted
region of the posterior pole. At baseline the central
vision was hand motions. By week 2, best corrected
visual acuity was improved to counting fingers (one
ETDRS letter). We recorded continued improvement
during the study period (five ETDRS letters [best
corrected visual acuity 20/800] at 1, 2, and 3 months;
table). The patient is very reliable and worked for years
as a graphic artist. She reports subjectively improved
colour vision and improved contrast and dark adaptation
from the operated eye. Importantly, we have not detected
functional visual change in the fellow eye, and no
subjective improvement to the fellow eye has been
reported. Similarly, Goldman visual fields done by an
Figure 4: Images of the hESC-RPE transplantation site in the patient with Stargardt’s macular dystrophy
Colour fundus photographs of the patient’s left macula preoperatively and postoperatively (A–C). The region inside the rectangle bisects the border of the surgical
transplantation site and corresponds to macular atrophy not included in the surgical injection. (A) Baseline macular colour image with widespread RPE and
neurosensory macular atrophy. (B) Colour macular image 1 week after hESC-RPE transplantation. Note the mild pigmentation most evident in the region of baseline
RPE atrophy. This pigmentation increased at week 6 (C). (D–G) Colour fundus photographs and SD-OCT images at baseline (D) and month 3 after transplant (F).
Colour images show increasing pigmentation at the level of the RPE from baseline to month 3. Registered SD-OCT images (E, G) show increasing pigmentation is at
the level of the RPE, normal monolayer RPE engraftment, and survival at month 3 (arrow) adjacent to region of bare Bruch’s membrane devoid of native RPE.
hESC=human embryonic stem cells. RPE=retinal pigment epithelium. SD-OCT=spectral domain ocular coherence tomography.
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2 7
experienced certified examiner from whom the
treatment was not masked showed no diminution of
visual field and could reasonably be interpreted as
improved (preoperative and post operative fields are
shown in the webappendix).
The therapeutic use of hESCs poses daunting translational
challenges. We provide clinical evidence suggesting that
hESC-derived cells might be safely transplanted into
human patients (panel). In our study, we transplanted a
low dose (5×10⁴ cells) of RPE cells generated from hESCs
into one eye of two patients with different forms of
To optimise the chances the cells would attach to
Bruch’s membrane, we selected a submacular injection
site where the macular anatomy (photoreceptors, Bruch’s
membrane, and RPE) was still present and potentially
viable, thus maximising the potential that the trans-
planted cells would integrate with the native RPE and
rescue compromised perimacular tissue. Both patients
tolerated the transplant well without signs of post-
operative inflammation, rejection, or tumorigenicity at
the time of this report. Although the 4 month follow-up
reported herein is short, ours and other studies confirm
that teratoma formation usually happens within
8 weeks1,19,21,25,26 and is often detected within 4 weeks
after transplanta tion.19,23 At 3 months, there was a nearly
four-times increase in the weight of the eyes of animals
injected with undifferentiated hESCs because of teratoma
growth. Similarly, immune rejection and clinical ocular
safety signals relating to intraocular inflammation were
expected during this period—we detected none. Although
we did not detect any signs of transplant rejection or
inflammation, it is possible the transplant was
Our findings suggest that transplanted hESC-RPE
cells in the patient with Stargardt’s macular dystrophy
attached to Bruch’s membrane and persisted for the
duration of our observation period. At present, we do
not know if the transplanted cells have reduced
immuno genicity or whether they will undergo rejection
without immuno suppression in the long term.
Similarly, we are uncertain at this point whether any of
the visual gains we have recorded were due to the
transplanted cells, the use of immunosuppressive
drugs, or a placebo effect.
Although the transplantation of intact sheets and
suspensions of primary RPE cells has been previously
attempted,11–18 RPE derived from adult and paediatric
donors are restricted in both their capacity to proliferate27
and their ability to differentiate in vitro.28 Clinically,
sheets of adult RPE engrafted into the subretinal space of
patients with dry age-related macular degeneration have
failed to improve visual function.29 Although RPE derived
from prenatal and postnatal tissue has been successfully
dissociated and induced to grow in vitro,30–32 such sources
are extremely limited and variable with regard to quality
and expansion capacity. By contrast with adult and fetal
tissue, a central feature of hESCs is that they have the
capacity to proliferate indefinitely, providing a virtually
unlimited source of youthful cells as starting material.
Another crucial advantage is that the stage of in-vitro
differentiation can be controlled to maximise survival
and functionality. Attachment of the transplanted cells to
(number of letters)
hESC=human embryonic stem cells. RPE=retinal pigment epithelium. BCVA=best
corrected visual acuity. ETDRS=Early Treatment Diabetic Retinopathy Study visual
Table: Change in visual acuity after hESC-RPE transplantation in patient
with Stargardt’s macular dystrophy
Panel: Research in context
We search PubMed for all publications, including clinical
trials, meta-analyses, and reviews, with the terms “age-
related macular degeneration”, “dry-AMD”, “Stargardt’s
macular dystrophy”, “Stargardt’s disease”, and “stem cells”
and identified no similar studies. Although several new drugs
are available for the treatment of the exudative (wet) type of
age-related macular degeneration, no proven treatments
exist for patients with geographic atrophy (dry age-related
macular degeneration).23 Evidence from studies in animals
suggests that stem cells could be useful as part of new
treatment strategies for currently incurable degenerative
Our study provides the first description of hESC-derived cells
transplanted into the eyes of patients with two different
forms of macular degeneration.
www.thelancet.com Published online January 23, 2012 DOI:10.1016/S0140-6736(12)60028-2
Bruch’s membrane, and their subsequent survival and
integration into the host RPE layer is crucial to the
success of this therapeutic strategy. Our data show that
the extent of RPE maturity and pigmentation might
substantially affect subsequent attachment and growth of
the cells in vitro.
Our study is designed to test the safety and tolerability
of hESC-RPE in patients with advanced-stage Stargardt’s
macular dystrophy and dry age-related macular degen-
eration. So far, the cells seem to have transplanted into
both patients without abnormal proliferation, teratoma
formation, graft rejection, or other untoward pathological
reactions or safety signals. Continued follow-up and
further study is needed. The ultimate therapeutic goal
will be to treat patients earlier in the disease processes,
potentially increasing the likelihood of photoreceptor and
central visual rescue.
SDS and J-PH performed the transplant surgeries. SDS, J-PH, GH,
VF-C, CKP, RMO, RG, IK, and RL contributed to data collection and
analysis. SDS, EM, RG, IK, and RL contributed to study design. SDS,
RG, IK, and RL contributed to literature search, data interpretation, and
writing of the report.
Conflicts of interest
EM, RG, IK, and RL are employees of Advanced Cell Technology, a
biotechnology company in the area of stem cells and regenerative
medicine. The other authors declare that they have no conflicts of
We thank M McMahon and J Grossman for assessment of patients and
follow-up; S Mishra and D Kohn for GMP therapeutic material
preparation; T Li, D Peak, and J Ratliff for their help in preparing the
RPE lot used in this study; C Immanuel for oversight of safety and
quality testing; and J Shepard and B Davis for assay development and
data collection, and E Haupt for clinical data monitoring.
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