Effect of proteoglycan purified from rat superior colliculus on the survival of murine retinal ganglion cells.

Recently, Schulz and coworkers purified a chondroitin sulfate proteoglycan from the superior colliculus of the neonatal rat which promoted survival of neonatal rat retinal ganglion cells in vitro. The present work tests whether this factor supports the survival of axotomised retinal ganglion cells in vivo. To this effect, murine retinae 15 and 20 days after conception were explanted to the chorioallantoic membrane of live chicken embryos. The explants, which were left in the egg for 1, 2 or 7 days, differentiated and grew according to a normal timetable. Purified proteoglycan from neonatal rat superior colliculus was applied daily to one group of retinae while a control group received Ham's F-10 medium. Results indicated that application of proteoglycan resulted in the preferential survival of large cells in the ganglion cell layer, namely ganglion cells, for up to 7 days post-explantation. In addition, the proteoglycan had a significant short-term anti-traumatic effect on the ganglion cell layer of explants by causing a 72% decrease in the number of dead cells relative to controls 1 day post-explantation. It was concluded that the chondroitin sulfate proteoglycan purified from the superior colliculus of the neonatal rat promotes the survival of fetal and neonatal murine retinal ganglion cells in retinae explanted to the chorioallantoic membrane of the chick.