Recombinant Forms of the Neurotrophic Factor Pigment Epithelium-Derived Factor Activate Cellular Metabolism and Inhibit Proliferation of the RAW Macrophage Cell Line

Abstract
Recombinant forms of the neurotrophic factor pigment epithelium-derived factor (PEDF) activate metabolism of RAW macrophage cells while simultaneously inhibiting their proliferation. The recombinant forms (rPEDF) acted with EC50s of 0.1–1 nM while full-length native bovine PEDF was inactive. Urea, which is the buffer used to extract recombinant PEDF, stimulated RAW cell proliferation, the first report of an effect of urea on non-kidney cells. PEDF acted within 12 h and its effects persisted up to 72 h with continuous exposure. Although rPEDF had no direct action on glioma cell lines, it increased the amount of a soluble factor released by RAW cells which was capable of blocking glioma cell division. Thus PEDF may function as a neuroimmune modulator, affecting both neural and immune system cells.