人工血管開発における研究の動向

人工血管の開発研究における動向について，我々の行ってきた研究をまじえて世界の動きを解析した。近年の砺究の流れは過去1世紀にわたる試行錯誤の上にあって，さらに大きく揺れ動いている。人工血管の内面に必要な抗血栓性の獲得においても，設計者によって考えを異にし，米国では，人工心臓に用いる抗血栓性合性高分子材料をもってそれに当てようとしているものが多い。我々はあくまで宿主のもつ諸機能を引き出し，自然の動きの一つとしての治癒を無理なく導いて，内皮細胞によって内面を覆わせる方法を採用している。そのいくつかの例として，超極細ポリエステル繊維製人工血管，結合組織管，バイオマトリックス人工血管，ヘパリン化生体組織由来人工血管，成長できる人工血管などについて解説した。

Vascular prostheses have been used in the treatments of various vascular diseases. We expect much from their contribution in the field of further fine vascular surgery. In this communication, new trend of the development of them with our new ideas in our recent research works were described. 1. Healing process of fabric vascular prostheses. Neointima formation of the vascular prosthesis implanted in the descending thoracic aortae of experimental animals were described in detail. This showed a standard behaviour of various cells which contributed the construction of a new arterial wall. 2. Problems of vascular prostheses which were used in clinic. Several problems such as a bleeding from the graft wall, aneurysmal dilatation, and degenerative changes of the neointimae were explained in detail. These problems were related with the structure of each vascular prosthesis. 3. Vascular prostheses developing with new ideas. Several vascular prostheses developing today were described as follows. (a) Fabric prosthesis with high healing ability. A prosthesis made of ultra-fine polyester fibers which can accerelate cell migration and proliferation inside the prosthetic wall was introduced. The neointima in this prosthesis was constructed very rapidly compared with that of the prostheses made of polyester fiber ordinally used. (b) Antithrombogenic small diameter vascular prostheses. Large caliber vascular prostheses have been used very safely in clinic, however, small diameter ones were seldom used due to its low patency rate by their occlusion. The grafts should have an antithrombogenic property to prevent the thrombus formation. Recently, some technologies to give antithrombogenic property to the vascular prostheses were developed. They were a heparin slow release technique, antithrombogenic segmented polyurethane, highly hydrous surface, heparinized collagen tube, etc. They were applied for the development of small diameter vascular grafts and showed good results in some animal experiments. (c) Growable vascular graft. A vascular graft which can grow with the growth of its recipient baby was demonstrated. The animal study showed as expected growth and stop growing at the expected time. (d) Vascular graft for aorto-coronary bypass surgery. A small diameter antithrombogenic, and flexible vascular grafts were explained. They were developed along our own ideas. This showed high patency rate m animal experiments. (e)Endothelial cell seeding techniques. In human, endothelialization m the vascular grafts is delayed and the inner surface was thrombogenic for a long period of time. To accerelate the endothelialization, cell seeding technique have been investigated in the last decade. We developed a new technology to transplant autologous cells in the peripheral vein tissue for this purpose. This was very reliable and simple. It was applicable in any hospital without any special technique and facility. Peripheral venous tissue fragments were transplanted into the fabric vascular prosthetic wall. Endothelial cells and smooth muscle cells migrated and proliferated from the tissue fragments. The neointima was constructed very rapidly with this active cell migrations.