In late stages of inherited and acquired retinal diseases such as Stargardt disease (STGD) or dry age-related macular degeneration (AMD), loss of retinal pigment epithelia (RPE) cells and subsequently photoreceptors in the macular area result in a dramatic decline of central visual function. Repopulating this area with functional RPE cells may prevent or decline the progression of photoreceptor loss. In the present study, the viability, survival, and integration of human induced pluripotent stem cell (hiPSC)-derived RPE cells (hiPSC-RPE) is assessed generated using clinical-grade protocol and cultured on a clinically relevant scaffold (poly-L-lactide-co-D, L-lactide, PDLLA) after subretinal implantation in immunosuppressed minipigs for up to 6 weeks. It is shown that transplanted hiPSC-RPE cells maintain the RPE cell features such as cell polarity, hexagonal shape, and cell-cell contacts, and interact closely with photoreceptor outer segments without signs of gliosis or neuroinflammation throughout the entire period of examination. In addition, an efficient immunosuppressing strategy with a continuous supply of tacrolimus is applied. Continuous verification and improvement of existing protocols are crucial for its translation to the clinic. The results support the use of hiPSC-RPE on PDLLA scaffold as a cell replacement therapeutic approach for RPE degenerative diseases.

• Keywords
• Human induced pluripotent stem cells;minipigs, age‐related macular degeneration, cell therapy, retina, retinal degeneration, retinal pigment epithelium,
• MeSH
• Photoreceptor Cells * MeSH
• Induced Pluripotent Stem Cells * cytology   transplantation   MeSH
• Humans MeSH
• Macular Degeneration therapy   MeSH
• Swine, Miniature MeSH
• Swine MeSH
• Retina * cytology   MeSH
• Retinal Pigment Epithelium * cytology   transplantation   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Age-related macular degeneration (AMD) is the most frequent cause of blindness in developed countries. The replacement of dysfunctional human retinal pigment epithelium (hRPE) cells by the transplantation of in vitro-cultivated hRPE cells to the affected area emerges as a feasible strategy for regenerative therapy. Synthetic biomimetic membranes arise as powerful hRPE cell carriers, but as biodegradability is a requirement, it also poses a challenge due to its limited durability. hRPE cells exhibit several characteristics that putatively respond to the type of membrane carrier, and they can be used as biomarkers to evaluate and further optimize such membranes. Here, we analyze the pigmentation, transepithelial resistance, genome integrity, and maturation markers of hRPE cells plated on commercial polycarbonate (PC) versus in-house electrospun polylactide-based (PLA) membranes, both enabling separate apical/basolateral compartments. Our results show that PLA is superior to PC-based membranes for the cultivation of hRPEs, and the BEST1/RPE65 maturation markers emerge as the best biomarkers for addressing the quality of hRPE cultivated in vitro. The stability of the cultures was observed to be affected by PLA aging, which is an effect that could be partially palliated by the coating of the PLA membranes.

• Keywords
• AMD, DNA damage, RPE, eye, gene expression, nanofibrous membrane, retina, retinal pigment epithelium,
• Publication type
• Journal Article MeSH

Retinal pigment epithelium (RPE) is a critical cell monolayer forming the blood-retina-barrier (BRB) and a permeable bridge between the choriocapillaris and the retina. RPE is also crucial in maintaining photoreceptor function and for completing the visual cycle. Loss of the RPE is associated with the development of degenerative diseases like age-related macular degeneration (AMD). To treat diseases like AMD, pluripotent stem cell-derived RPE (pRPE) has been recently explored extensively as a regenerative module. pRPE like other ectodermal tissues requires specific lineage differentiation and long-term in vitro culturing for maturation. Therefore, understanding the differentiation process of RPE could be useful for stem cell-based RPE derivation. Developing pRPE-based transplants and delivering them into the subretinal space is another aspect that has garnered interest in the last decade. In this review, we discuss the basic strategies currently employed for stem cell-based RPE derivation, their delivery, and recent clinical studies related to pRPE transplantation in patients. We have also discussed a few limitations with in vitro RPE culture and potential solutions to overcome such problems which can be helpful in developing functional RPE tissue.

• Keywords
• cell delivery, differentiation, embryonic stem cells, induced pluripotent stem cells, retinal pigment epithelium,
• MeSH
• Cell Differentiation MeSH
• Humans MeSH
• Macular Degeneration * therapy   metabolism   MeSH
• Pluripotent Stem Cells * MeSH
• Retina MeSH
• Retinal Pigment Epithelium metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH