Aim: To extract and purify the transforming growth factor beta (TGF beta), and to demonstrate its biological activity in vivo and induction of apoptosis of hepatocytes in vitro.
Methods: TGF beta was isolated from fresh bovine platelets by acid/ethanol extraction method and purified with ion exchange and gel chromatography. The extracted TGF beta was injected subcutaneously to mice, and its biological activity in vitro was observed 72 hrs post-injection by HE staining. The morphological changes were observed by HE staining and the occurrence of apoptosis was detected by TUNEL method after the human normal hepatic cell line QZG was treated with 8 microg.(-1)TGFbeta for 12 hrs in vitro.
Results: The molecular mass 25 ku TGFbeta protein was successfully extracted. It was able to induce localized granulation tissue formation in vitro. TGF beta-treated hepatocytes showed obvious apoptotic morphological changes, including the pyknosis and dense-stained nuclei and cytoplasm, the fragmentary, annular or crescent nuclei, and the "bubbling" cytoplasm. Moreover, its apoptotic rate was significantly higher than that of the control group (P<0.05).
Conclusion: Biological active TGF beta protein is extracted and purified successfully from bovine platelets, and it is able to induce the apoptosis of hepatocytes.