Purchase this article with an account.
Jie Zhu, Joseph Reynolds, Deepak A Lamba; Defining parameters for photoreceptor replacement therapy. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1276.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Retinal degeneration often results in the loss of photoreceptors. Generating transplantable photoreceptors from human embryonic stem cells (hESCs) to replace lost cells holds promise to treat a variety of retinal degenerative diseases. Parameters that are critical for improving the efficiency of integration are needed to advance photoreceptor replacement therapy to the clinic. This study describes several factors influencing integration and maturation of hESC-derived photoreceptors in host mouse retinas.
hESC-derived photoreceptors were generated as previously described (Lamba et al 2006). The cells were characterized via QPCR and immunocytochemistry 3 and 5 months after directed differentiation. Some of the experiments involved 24-hour pretreatment of the cells in vitro with Notch inhibitor, DAPT, prior to transplantation. GFP expressing retinal cells were injected into the subretinal space of 4-6 week old mice including IL2rg-/-, Crxtvrm65 and Crx tvrm65/IL2rg-/- mice. Eyes were collected at several time points to analyze integration and maturation of donor cells by immunohistochemistry.
Upon transplantation of hESC-derived retinal cells cultured for 3 months, more photoreceptors integrate into host normal retinas at 3 months compared to 6 weeks. The integrated cells express mature rod and cone markers including opsins. Donor cells cultured for 5 months integrated much faster into the host retina. At 6 weeks post transplantation, we observed integrated mature rod and cone photoreceptors indicating prolonged differentiation in vitro promotes integration. In addition, pretreatment of cells in vitro with DAPT to drive differentiation also promoted integration. Finally, donor photoreceptors transplanted into Crxtvrm65 had lower survival and integration at 3 months. Immunosuppression (Crx tvrm65/IL2rg-/-) improved integration of photoreceptors in these mice but was still lower than in normal retinas.
In conclusion, our work has identified a set of important parameters for effective integration of hESC-derived photoreceptors. Integration requires immunosuppression especially against xenorejection. Promoting differentiation of photoreceptors either via prolonged culture or transient Notch signaling inactivation facilitates the integration of donor cells in host retinas. In general, integration is worse in degenerating retinas suggesting a need for additional strategies.<br />
This PDF is available to Subscribers Only