Abstract
Purpose::
A current goal of stem cell research is to generate differentiated cell types for transplantation, but it is not known whether differentiated retinal neurons, for example, will integrate into the adult retina. The purpose of this study was to evaluate the survival and integration of purified rat retinal ganglion cells (RGCs) following intravitreal transplantation into wild-type mature rat eyes.
Methods::
Postnatal day 5 rat retinas were digested and RGCs purified by immunopanning. RGCs were labeled with CFDA fluorescent dye for identification post-transplant. MTT assays were performed to assess the survival and viability of cells prior to transplantation. Between 2x104-2x105 RGCs in 2 µL were transplanted intravitreally into adult wild-type rat eyes. The injected animals were sacrificed and enucleated at various time points (1 hour, 1 day, 2 days, 1 week) following injection. The enucleated globes were cryo-sectioned and mounted. The resulting histologic sections were stained with DAPI nuclear and other markers and evaluated by light microscopy.
Results::
MTT survival assays demonstrated that RGC survival was not adversely affected by intravitreal injection. At 1 hour following intravitreal injection of purified postnatal RGCs, transplanted cells and cell aggregates were seen layering along the retinal surface. At later time points, rare examples of retinal integration were seen.
Conclusions::
Transplanted RGCs do not appear to easily integrate into wild-type rat retinas. Further data regarding cell viability and integration at extended post-transplantation intervals is necessary to evaluate the feasibility of transplantation of differentiated RGCs in this animal model. Future experiments will examine the role of host factors such as age and prior retinal or optic nerve injury.
Keywords: ganglion cells • transplantation • retina