NEUROGENIC SUBSTANCE-P STIMULATES OSTEOGENESIS IN-VITRO

Previous studies have shown that there is colocalization of substance P (SP) and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in bone, periosteum and bone marrow. Because SP may also possi bly play a role in bone formation, we decided to test whether it has a n osteogenic stimulating effect on developing bone in vitro. To this e nd, 0.4, 4 and 40 mu g/ml of SP in BGJb medium was added daily to 3 mi llion light density (LD) bone marrow white cells which were separated by Ficoll-Paque density gradient separation then seeded onto a previou sly prepared fibroblast feeder layer in Petri dishes. Seven days after adding SP, in the control without SP there were 2 bone colonies; with 0.4 mu g of SP there were 3 colonies; with 4 mu g there were 5 coloni es; with 40 mu g there were 7 colonies. In addition, there was an incr ease in the size of bone colonies in the SP-added group. The results i ndicated that SP had a dose-related osteogenic stimulating effect. The increase in the number and size of bone colonies by SP was probably c aused by stimulating stem cell mitosis, osteoprogenitor cell different iation or osteoblastic activity. (C) 1997 Elsevier Science Inc.