Abstract
Purpose: :
Retinal progenitor cells (RPCs) continuously proliferate in serum–free culture, and co–express nestin and retinal specific neuronal markers while undergoing an in vitro neuronal linage differentiation pathway. This study investigated the proliferation and differentiation characteristics of RPCs in vivo at different time points following subretinal transplantation in retinal degenerate rats.
Methods: :
Embryonic day17 derived rat retinal progenitor cells (RPCs) were cultured and expanded in serum free media. Passage 2 RPCs were transplanted into the subretinal space of postnatal day 48 S334ter–3 rats (12 rats received RPC transplants and 4 received PBS injections). The total 16 rats were evenly divided into 4 groups and sacrificed at postoperative week 1,2,3,4 respectively. All rats were examined by biomicroscopy and fluorescein angiography (FA) at postoperative week one, and received peritoneal injections of BrdU for 3 consecutive days prior to sacrifice. Serial cryosections containing RPC transplants were stained by immunohistochemistry for nestin, BrdU, glial fibrillary acidic protein (GFAP), as well as for retinal specific neuronal markers.
Results: :
Postoperative biomicroscopy and FA demonstrated no significant inflammatory reaction following RPC transplantation in any animal, and only mild subretinal hemorrhages in 3 rats.BrdU immunoreactive cells were not observed within the RPC grafts or in the degenerated retina (of PBS injected animals) at any follow–up time point. Nestin expression was upregulated in the transplanted area (both within the graft and the host retina), and the pattern of nestin staining was similar to that of GFAP.
Conclusions: :
Proliferation of RPCs appears to cease immediately after subretinal transplantation in end–stage retinal degeneration rats. The subretinal environment of adult retinal degenerate rats may harbor inhibitory cues for cell proliferation.
Keywords: retina • transplantation • retinal development