The utilization of fluorescent reporter transgenes to discriminate donor versus host cells has been a mainstay of photoreceptor transplantation research, the assumption being that the presence of reporter1 cells in outer nuclear layer (ONL) of transplant recipients represents the integration of donor photoreceptors. We previously reported that GFP 1 cells in the ONL of cone-GFP transplanted retinas exhibited rod-like characteristics, raising the possibility that GFP signal in recipient tissue may not be a consequence of donor cell integration. To investigate the basis for this mismatch, we performed a series of transplantations using multiple transgenic donor and recipient models, and assessed cell identity using nuclear architecture, immunocytochemistry, and DNA prelabeling. Our results indicate that GFP 1 cells in the ONL fail to exhibit hallmark elements of donor cells, including nuclear hetero/euchromatin architecture. Furthermore, GFP signal does not appear to be a consequence of classic donor/host cell fusion or transfating post-transplant, but is most likely due to material exchange between donor and host photoreceptors. This transfer can be mediated by rods and cones, is bidirectional between donor and host cells, requires viable photoreceptors, occurs preferentially at sites of outer limiting membrane disruption and can be detected in second-order retinal neurons and M€ uller glia. Collectively, these data warrant re-evaluation of the use of lineage tracing fluorescent reporters in transplantation studies involving the retina and other CNS tissues. Furthermore, the reinterpretation of previous functional rescue data, based on material exchange, rather than cell integration, may offer a novel approach to vision rescue. STEM CELLS 2017;35:932-939 SIGNIFICANCE STATEMENTGFP labeled photoreceptors are observed in the outer nuclear layer of recipient retinas following transplantation of GFP-tagged photoreceptors. The historical interpretation of this observation has centered around the migration of donor cells into recipient retina, and maturation of these cells into functional photoreceptors. This study challenges this interpretation by showing that there is almost no donor cell integration into intact retinal tissue, and provides evidence that the origin of the GFP signal in the recipient retina is due to exchange of GFP signal between donor and host retinal cells. This work reveals that the adult retina is not as receptive to donor cell integration as was previously thought and deepens our understanding of how photoreceptor therapy, via material exchange, could work therapeutically.

Platinum-based chemotherapy is widely used to treat various cancers. However, exogenous platinum is apt to cause severe side effects and drug resistance induced by upregulated glutathione (GSH) in cancer cells...

No abstract

No abstract

No abstract