MedicalResearch.com Interview with: Won Kyung Song MD.PhD Assistant Professor, Vitreoretinal service, Department of Ophthalmology CHA Bundang Medical Center CHA University Republic of Korea

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: The retina is a light-sensitive neural tissue lining the inner surface of the human eye. The center of this retina is calledthe macula, which is responsible for high quality vision and central visual field. Retinal pigment epithelium is a layer of cells in the outer layer of the retina which has a critical role in maintaining and supporting the retina, especially the macula.

Age-related macular degeneration(AMD) is the leading cause of vision loss in the elderly in Western countries. There are two types of AMD, wet (neovascular or exudative) and dry (atrophic).The retinal pigment epithelium and choroid, are closely related with the pathophysiology of AMD. In dry AMD,age-relateddegeneration ofRPE cellsleads to the loss of photoreceptor cells and visual deficit. Currently, some therapies are available for amelioratingthe wet AMD. However, there are no effective therapy available for dry AMD.

Previous studies have shown that healthy RPE cells can be implanted to replace unhealthy RPE cells in lesion areas where RPE cells have been lost.Allogenic RPEs resulted in graft rejection and autologous RPEs are difficult to harvest leading to surgery related complications. Now, abundant RPEs with stable genotype and phenotyemay be generated from embryonic stem cells. Therefore, we have undergone subretinal transplantation of human embryonic stem cell derived RPE cells. (Clinicaltrials.govNCT 01674829)Among the patients enrolled for

this clinical trial, we noted epiretinal membrane(ERM) with pigmentations over the retina in a proportion of patients as an adverse event. One patientwithdry AMD and an epiretinal membrane after the hES-RPE transplantationundergoneremoval of this ERM. The histologic examination of this ERM with pigmentations showed that the pigmented cellsoriginatedfrom thetransplantedhES-RPE cells which survived in the recipient for 22 months without anaplasia.

MedicalResearch.com: What should readers take away from your report?

Response: The main concerns of clinical application of hES derived cellsaretumorigenesisand immune rejection.

Thereare limitations of these trials lackingconfirmative measurements of engraftment of the transplanted cells. Because biopsy of the retina results in focal loss of nurosensory retina and labelling the cells may cause additional clinical harm.

This is the first report showing that hES derived cells has survived upto 22 months in human organwithout anaplasia and may form an ERM.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: Objective measurement of engraftment is necessary, together with advancement of an objective visual function measurements.

MedicalResearch.com: Is there anything else you would like to add?

Response: The case reported in thisjournalis a finding froma patient enrolled in the clinical trial sponsored byCHAbiotech.Co,Ltd.

HI12C1794(A121941)

MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.

Citation:

Shim SH, Kim G, Lee DR, Lee JE, Kwon HJ, Song WK. Survival of Transplanted Human Embryonic Stem CellDerived Retinal Pigment Epithelial Cells in a Human Recipient for 22 Months. JAMA Ophthalmol. Published online February 09, 2017. doi:10.1001/jamaophthalmol.2016.5824

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Transplanted Human Embryonic Stem Retinal Pigment Cells Survive 22 months in a Human Recipient - MedicalResearch.com (blog)