Ueda Hiroki, Hong Liu, Yamamoto Masaya, Shigeno Keiji, Inoue Masatoshi, Toba Toshinari, Yoshitani Makoto, Nakamura Tatsuo, Tabata Yasuhiko, Shimizu Yasuhiko
Institute for Frontier Medical Sciences, Kyoto University, Japan.
Biomaterials. 2002 Feb;23(4):1003-10. doi: 10.1016/s0142-9612(01)00211-3.
The objective of this study was to evaluate the potential of collagen sponge incorporating transforming growth factor-beta1 (TGF-beta1) to enhance bone repair. The collagen sponge was prepared by freeze-drying aqueous foamed collagen solution. Thermal cross-linking was performed in a vacuum at 140 degrees C for periods ranging from 1 to 48 h to prepare a number of fine collagen sponges. When collagen sponges incorporating 125I-labeled TGF-beta1 were placed in phosphate-buffered saline (PBS) solution at 37 degrees C, a small amount of TGF-beta1 was released for the first hour, but no further release was observed thereafter, irrespective of the amount of cross-linking time the sponges had received. Collagen sponges incorporating 125I-labeled TGF-beta1 or simply labeled with 125I were implanted into the skin on the backs of mice. The radioactivity of the 125I-labeled TGF-beta1 in the collagen sponges decreased with time; the amount of TGF-beta1 remaining dependent on the cross-linking time. The in vivo retention of TGF-beta1 was longer in those sponges that had been subjected to longer cross-linking times. The in vivo release profile of the TGF-beta1 was matched with the degradation profile of the sponges. Scanning electron microscopic observation revealed no difference in structure among sponges subjected to different cross-linking times. The TGF-beta1 immobilized in the sponges was probably released in vivo as a result of sponge biodegradation because TGF-beta1 release did not occur in in vitro conditions in which sponges did not degrade. We applied collagen sponges incorporating 0.1 microg of TGF-beta1 to skull defects in rabbits in stress-unloaded bone situations. Six weeks later, the skull defects were covered by newly formed bone, in marked contrast to the results obtained with a TGF-beta1 free empty collagen sponge and 0.1 microg of free TGF-beta1. We concluded that the collagen sponges were able to release biologically active TGF-beta1 and were a promising material for bone repair.
本研究的目的是评估含有转化生长因子-β1（TGF-β1）的胶原海绵促进骨修复的潜力。胶原海绵通过冻干水性泡沫胶原溶液制备。在140℃真空条件下进行热交联1至48小时，以制备多种优质胶原海绵。当将含有125I标记的TGF-β1的胶原海绵置于37℃的磷酸盐缓冲盐水（PBS）溶液中时，最初1小时会释放少量TGF-β1，但此后无论海绵接受的交联时间长短，均未观察到进一步释放。将含有125I标记的TGF-β1或仅标记有125I的胶原海绵植入小鼠背部皮肤。胶原海绵中125I标记的TGF-β1的放射性随时间降低；剩余的TGF-β1量取决于交联时间。交联时间越长的海绵，TGF-β1在体内的保留时间越长。TGF-β1的体内释放曲线与海绵的降解曲线相匹配。扫描电子显微镜观察显示，不同交联时间的海绵在结构上没有差异。固定在海绵中的TGF-β1可能由于海绵的生物降解而在体内释放，因为在海绵不降解的体外条件下未发生TGF-β1释放。我们将含有0.1μg TGF-β1的胶原海绵应用于处于应力卸载骨状态的兔颅骨缺损处。六周后，颅骨缺损被新形成的骨覆盖，这与使用不含TGF-β1的空白胶原海绵和0.1μg游离TGF-β1所得到的结果形成显著对比。我们得出结论，胶原海绵能够释放生物活性TGF-β1，是一种有前景的骨修复材料。
