TGF-β诱导体内成骨效应

Effects of transforming growth factor β upon in vivo osteogenesis

目的：β转化生长因子（ＴＧＦ┐β）可诱导间充质细胞合成软骨特异性蛋白聚糖和Ⅱ型胶原，刺激成骨细胞的增殖及胶原合成．本实验旨在探讨牛血小板ＴＧＦ┐β在体内的成骨活性．方法：以牛血小板为原料，采用酸醇抽提方法，提取血小板蛋白．经柱层析纯化出其中分子质量为２５ｋｕ的ＴＧＦ┐β．在小鼠股骨中下段前方骨膜下注射ＴＧＦ┐β溶液２０μｌ（含ＴＧＦ┐β４００ｎｇ）；每日一次，最长连续注射１０次．结果：骨膜下注射ＴＧＦ┐β，注射后第３日，骨膜间充质细胞增殖、软骨细胞分化；第７日开始软骨细胞大量增殖，并有软骨内化骨效应；第１４日，大量新生骨痂形成；随后骨改建，出现板层骨．结论：骨膜下注射ＴＧＦ┐β导致局部新生骨质形成过程与正常骨折愈合时相一致，表明外源性的ＴＧＦ┐β可以启动骨生成过程；

Objective: Transforming growth factor β (TGF β) induces the synthesis of cartilage specific proteoglycan and type Ⅱ collagen by mesenchymol/Lal cells and stimulates proliferation and collagen synthesis by osteoblasts. The aim of the present study was to demonstrate the biologic activities of TGF β after injecting it into subperiosteum in vivo . Methods: TGF β, purified from the acidic ethanol extracts of bovine blood platelets, was injected daily into subperiosteum of adult mouse femurs. At 3, 7, 14, 21, 28 d after injection, the animals were sacrificed separately for histological observation. Results: After 2 injections of TGF β, mesenchymal cells in periosteum proliferated greatly with differentiated chondrocytes. Chondrocytes increased obviously after 6 continous injections of TGF β. Endochondral osteogenesis increased greatly at the 14th day. After cessation of the injections, endochondral ossification occurred widely, resulting in replacement of cartilage with new bone. Conclusions: These data demonstrate that exogenous TGF β stimulates mesenchymal proliferation and differentiation as occurs in early fracture healing, suggesting the possibility of clinical application of TGF β for the fracture repair and bone transplantation.