Biomaterials combined with Engineered Growth Factors with collagen binding affinity for tissue regeneration.

我们通过融合纤连蛋白胶原结合结构域（CBD）来改造生长因子（EGF、HGF、VEGF等）以赋予胶原结合活性。所得工程化生长因子显示稳定的结合活性。当它们与胶原结合时，细胞生长促进活性也得到改善。固定在培养容器中的一种这样的融合蛋白（CBD-HGF）继续刺激内皮细胞的生长，而无需更换培养基。也就是说，在延长培养期间，不需要额外的因子。本研究将CBD-HGF与组织工程材料相结合，进一步探讨CBD-HGF在再生医学中的应用。1）将CBD-HGF与小口径人工血管（直径3 mm，ePTFE）复合，植入犬股动脉。与对照血管和天然HGF处理的血管相比，植入的血管显示出更早的内皮化（4周）。2）胶原海绵与CBD-HGF联合应用于大鼠皮下移植2周后可诱导大量血管生成，而对照组和HGF处理的海绵血管生成最少。3）CBD-HGF灌注大鼠颈动脉球囊损伤后，可促进损伤区的内皮化。本研究的结果表明，胶原结合生长因子在以下几个方面的应用：1）细胞治疗的培养系统，2）生物材料结合生长因子活性诱导组织修复，3）药物诱导组织修复。

We engineered growth factors (EGF, HGF, VEGF etc) to confer collagen binding activity by fusion of fibronectin collagen-binding domain (CBD). Resulting engineered growth factors showed stable binding activity. Cell growth promotion activity was also improved when they were combined with collagen. One of such fusion protein (CBD-HGF) immobilized to the culture vessels continued to stimulate growth of endothelial cells without medium change. That is, additional factor was unnecessary during prolonged culture. This will be suitable for developing culture system (or bioreactor) of growing large number of cells for cell-implantation therapy.We further examined CBD-HGF on the applicability to regenerative medicine by combining with tissue engineering materials as follows.1) Small caliber artificial blood vessels (3mm in diameter, ePTFE) were combined with CBD-HGF and implanted into dog femoral artery. The implanted vessels showed earlier endothelialization (4weeks) as compared to control vessels and native HGF treated vessels. The fusion HGF may be used to develop implantable vessels with long patency for bypass graft of coronary artery.2) Collagen sponges combined with CBD-HGF induced extensive angiogenesis by 2 weeks after implantation into rat subcutaneous tissue, while control and HGF-treated sponge showed minimal angiogenesis. The sponge may be useful to repair ischemic cardiac tissues, leg ulcer etc.3) CBD-HGF infused to balloon-injured carotid artery of rats promoted endothelialization of denuded areas. It may be used to prevent restenosis after angioplasty using balloon catheter.The results of the present study indicated the applicability of collagen-binding growth factor (s) in the following ways;1) Culture system for cell therapy, 2) biomaterial combined with growth factor activity to induce tissue repair and 3) medicine to induce tissue repair.