in situ Tissue Engineering on digestive systems.

胃肠道原位组织工程再生的研究在本研究项目中，我们尝试使用原位组织工程技术来再生整个消化系统各层。靶向胃肠道由四层组成：粘膜上皮、粘膜下结缔组织、肌肉和浆膜。产生消化液的腺体和常染色体神经位于这四层。将胶原海绵和PGA无纺布作为支架应用于再生部位。我们尝试了修复犬实验性胃、小肠、结肠、胆总管的缺损区。我们已经观察到这个系统中有缺陷的粘膜上皮、结缔组织和腺体的早期再生。然而，肌层(主要是平滑肌层)未能再生。为了解决这一问题，我们加入了生长因子(FGE、转化生长因子β)，但效果并不明显，这可能是由于缺乏干细胞以及血液供应不足所致。因此，在这个项目的最后一年，从宿主肌肉组织中分离出了祖细胞，并在体外进行了增殖。然后，我们尝试将这些增殖的细胞与血管诱导生长因子如血管内皮生长因子一起应用于促进肌肉组织的再生。利用这一技术，我们证实了在兔的肢体中可以产生肌样组织，并用人工可生物降解的神经导管桥接了腹内常染色体神经的缺损处，这有力地表明了PGA-胶原管作为神经导向器的可行性。因此，显然，即使是在像比格犬这样的大型哺乳动物中，利用原位组织工程技术制造消化组织似乎也是非常有吸引力的。

Research for the regeneration of the gastro-intestinal tract with in situ Tissue Engineering.In this research program, we tried to regenerate the whole layers of digestive system using in situ Tissue Engineering technique. Targeted gastro-intestinal tract is composed of four layers ; the mucous epithelium, the sub-mucosal connective tissue, the muscle, and the serosa. The glands which produce digestive juice and the autosomal nerves are situated in these four layers. As a scaffold, collagen sponge and the PGA unwoven fabric were applied to the site of the regeneration. We tried repair of the defect of the stomach, the small intestine, the colon, the common bile duct of canine experimental model. We have already observed the early regeneration of the defective mucous epithelium, the connective tissue, and the glands in this system. However, the muscle layers (mainly the smooth muscle) failed to be regenerated. To solve this problem, we had added the growth factors (FGE,TGF β) but the effect was not obvious.This may because of absence of the stem cell as well as poor blood supply. Therefore, in the last year of this project, the progenitor cells were isolated from the host muscle tissue and consequently proliferated in vitro. Then, we tried to apply these proliferated cells with vascular inductive growth factor such as VEGF to promote the regeneration of muscle tissue. Using this technique we confirmed that the muscle-like tissue could be produced in the lower extremities of rabbits.We bridged the nerve defect of the intraabdominal autosomal nerve with artificial biodegradable nerve guide tube, in which the feasibility of the PGA-collagen tube as a nerve guide were strongly indicated. Thus, apparently, even in large mammalians such as beagle dog, it seems highly promizing to make a digestive tissue with a technique of in situ Tissue Engineering.