CELLULAR-LOCALIZATION OF PDGF MESSENGER-RNAS IN DEVELOPING HUMAN FOREBRAIN

Platelet-derived growth factor (PDGF) has been implicated in the proce sses regulating gliogenesis in the CNS. Conflicting in vivo data in ro dents have variously implicated either glia or neurons as being the pr imary source of PDGF. We have used in situ hybridization and immunocyt ochemical analysis to study the in vivo expression and cellular locali zation of PDGF-A, sis/PDGF-B, together with the two PDGF receptors alp ha and beta, in developing human forebrain, In this study we demonstra te the strong expression of mRNA and protein of both EDGE chains, A an d B, and their receptors, alpha and beta, in human embryonic glial cel ls. The neurons, in contrast to glial cells, expressed lower levels of PDGF and PDGF-receptor mRNAs and protein. Identification of the cell types expressing the PDGF and PDGF-receptor mRNAs was achieved by coun terstaining with antibodies specific for glial cells (GFAP) and neuron s (NF). The predominant glial-specific expression of both PDGF-A and P DGF-B, together with the coexpression of their receptors alpha and bet a, suggests an important role for the PDGF isoforms in the development of human embryonic glial cells and neurons in vivo.