Differential effects of platelet-derived growth factors on fetal hippocampal and cortical grafts: evidence from intraocular transplantation in rats.

Effects of platelet-derived growth factor-AA (PDGF-AA) and platelet-derived growth factor-BB (PDGF-BB) on developing parietal cortex (E16) and hippocampal (E18-E19) grafts were studied using the in vivo method of intraocular transplantation. Survival and growth of grafts in the anterior eye chamber of adult host rats under the influence of regular treatments with 0.5 ng (in a 100 ng/ml concentration) PDGF-AA or PDGF-BB was followed and compared to those receiving vehicle solution alone (0.5 mg HSA/ml Hanks). Both PDGF-AA and PDGF-BB increased the volume of transplanted cortical grafts. PDGF-BB also exerted trophic effects on grafted hippocampal tissue whereas PDGF-AA seemed to inhibit hippocampal growth. Histological and immunohistochemical studies revealed an increase in the density of astroglial elements in PDGF-AA- and PDGF-BB-treated cortical grafts whereas the PDGF-AA- and PDGF-BB-treated hippocampal grafts maintained a cytoarchitecture closely resembling that of control grafts. These findings support in vitro experiments showing that developing glial cells are stimulated by PDGFs and we further propose regional differences of action of PDGFs in the developing central nervous system.