Experimental Studies Of The Efftects Of Transforming Growth Factor β(TGF-β) Upon Osteogenesis

TGF-β is an acid- and heat- stable, disulfide-linked homodimeric 25 KD protein that consists of two identical amino acid subunits. Total amino acid sequence deduced from the cDNA clones shows that the processed human and bovine TGF-β s are identical. TGF- β presents in most tissues and is known to play an important regulatory role in cell growth, migration and differentiation. TGF-β is present in blood platelets and bones in high quantities.TGF-β may be involved in bone formatoin. TGF-β also induces the synthesis of carlage-specific proteoglycan and type II collagen by mesenchymal cells and stimulates proliferation and collagen synthesis by osteoblasts. Studies have demonstrated synthesis of TGF- β by both chondrocytes and osteoblasts and accumulateion of TGF-β in an in vivo model of endochondral ossification. Based on the high concentration of TGF- β fond in bone, the effect of TGF-β on protein synthesis by chondrocytes and osteoblasts in vitro and the release of TGF-β into the fracture hematoma by platelets, TGF- β may be responsible for regulating cartilage and bone formation in the process of fracture and bone defect repair.The aims of the present study was to extract and purify TGF- β from bovine blood platelets, to demonstrate its biologic activities after injection into subperiosteum, to analyse its effects on bone repair when reconstituted with chemically treated bovine cancellous bone , and to compare its effects with that of TGF- β /BMP complex in a segmental bone defect model.1. Bovine blood platelet TGF-β — Extraction and purification and bloassayAcidic ethanol extracts of bovine platelets were purified to homogeneity by sequential gel filtration on Bio-Gel P60 columns, first in the absence and then in the presence of ultra-pure urea. As determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, the protein is mainly...