Photoreceptor degenerative diseases are a major cause of blindness for which cell replacement is one of the most encouraging strategies. For stem cell-based therapy using human induced pluripotent stem cells (hiPSCs), it is crucial to obtain a homogenous photoreceptor cell population. We confirmed that the cell surface antigen CD73 is exclusively expressed in hiPSC-derived photoreceptors by generating a fluorescent cone rod homeobox (Crx) reporter hiPSC line using CRISPR/Cas9 genome editing. We demonstrated that CD73 targeting by magnetic-activated cell sorting (MACS) is an effective strategy to separate a safe population of transplantable photoreceptors. CD73+ photoreceptor precursors can be isolated in large numbers and transplanted into rat eyes, showing capacity to survive and mature in close proximity to host inner retina of a model of photoreceptor degeneration. These data demonstrate that CD73+ photoreceptor precursors hold great promise for a future safe clinical translation.

Human ESC–derived retinal pigment epithelial cell sheets are more effective than cell suspensions at rescuing photoreceptor cell loss in rats with retinal dystrophy.

The rapid progress in the field of stem cell research has laid strong foundations for their use in regenerative medicine applications of injured or diseased tissues. Growing evidences indicate that some observed therapeutic outcomes of stem cell-based therapy are due to paracrine effects rather than long-term engraftment and survival of transplanted cells. Given their ability to cross biological barriers and mediate intercellular information transfer of bioactive molecules, extracellular vesicles are being explored as potential cell-free therapeutic agents. In this review, we first discuss the state of the art of regenerative medicine and its current limitations and challenges, with particular attention on pluripotent stem cell-derived products to repair organs like the eye, heart, skeletal muscle and skin. We then focus on emerging beneficial roles of extracellular vesicles to alleviate these pathological conditions and address hurdles and operational issues of this acellular strategy. Finally, we discuss future directions and examine how careful integration of different approaches presented in this review could help to potentiate therapeutic results in preclinical models and their good manufacturing practice (GMP) implementation for future clinical trials.

Dysfunction or death of retinal pigment epithelial (RPE) cells is involved in some forms of Retinitis Pigmentosa and in age-related macular degeneration (AMD). Since there is no cure for most patients affected by these diseases, the transplantation of RPE cells derived from human pluripotent stem cells (hPSCs) represents an attractive therapeutic alternative. First attempts to transplant hPSC-RPE cells in AMD and Stargardt patients demonstrated the safety and suggested the potential efficacy of this strategy. However, it also highlighted the need to upscale the production of the cells to be grafted in order to treat the millions of potential patients. Automated cell culture systems are necessary to change the scale of cell production. In the present study, we developed a protocol amenable for automation that combines in a sequential manner Nicotinamide, Activin A and CHIR99021 to direct the differentiation of hPSCs into RPE cells. This novel differentiation protocol associated with the use of cell culture robots open new possibilities for the production of large batches of hPSC-RPE cells while maintaining a high cell purity and functionality. Such methodology of cell culture automation could therefore be applied to various differentiation processes in order to generate the material suitable for cell therapy.

Huntington disease (HD) is associated with early psychiatric symptoms including anxiety and depression. Here, we demonstrate that wild-type huntingtin, the protein mutated in HD, modulates anxiety/depression-related behaviors according to its phosphorylation at serines 1181 and 1201. Genetic phospho-ablation at serines 1181 and 1201 in mouse reduces basal levels of anxiety/depression-like behaviors. We observe that the reduction in anxiety/depression-like phenotypes is associated with increased adult hippocampal neurogenesis. By improving the attachment of molecular motors to microtubules, huntingtin dephosphorylation increases axonal transport of BDNF, a crucial factor for hippocampal adult neurogenesis. Consequently, the huntingtin-mediated increased BDNF dynamics lead to an increased delivery and signaling of hippocampal BDNF. These results support the notion that huntingtin participates in anxiety and depression-like behavior and is thus relevant to the etiology of mood disorders and anxiety/depression in HD.