Abstract
Purpose: :
Mural (perivascular) cells, including pericytes help to maintain vessel stability and have an inhibitory effect on endothelial cell proliferation. In different organs the coverage of microvessels shows a significant difference. Retinal capillaries have a greater pericytic coverage than capillaries in many other organs. In diabetic retinopathy a significant decrease in the pericytic coverage has been reported. Interestingly, isolated mural cells of microvessels are endowed with Mesenchymal Stem Cell (MSC)-like traits capable of multilineage differentiation. Thus, MSC-like pericytes around retinal vessels could potentially represent a source for tissue regeneration. To establish a framework for future comparative and functional/regeneration studies we investigated the phenotypic features, development/age-related changes of pericytes and addressed their potential heterogeneity in situ on retinal vessels in two rodent species.
Methods: :
Rat and murine retinae were investigated at the end of the second postnatal week shortly after the release of the fusion of the eyelids and in young adult animals. In whole mount preparations and horizontal cryosections of these samples pericytes were identified based on the expression of NG2, a chondroitin sulfate proteoglycan. In double staining experiments, the samples were co-stained with a panel known stem/progenitor cell markers (e.g. CD146, Sox2) and were subsequently analyzed by epifluorescence.
Results: :
Our results show a distinct distribution pattern of perivascular NG2-positive cells around the retinal microvessels in postnatal and young adult rodents. Double staining in rats also reveals a phenotypic heterogeneity of the cells in adult perivascular cells based on expression of CD146. These data will be discussed.
Conclusions: :
Future studies are needed in order to assess the potential trans-differentiation capacity and enrolment in regenerative processes both in situ and on isolated and transplanted pericytes.
Keywords: retina • development • anatomy