生医工程人员不断的想出新的方法以取代现有以塑料、钛合金或陶瓷材质的医疗器材，因为这些材质大多不被身体所接受，时间一久就会损坏或老旧。布朗大学(Brown University)以及普度大学(Purdue University)的研究人员发现，只要简单地改变移植器材的表面结构，就能让体内的细胞生长而能预防再阻塞的情况。
最近有两份实验特别针对撑开血管的支架(stents)等材质进研究，分别发表于Tissue Engineering以及Journal of Biomedical Materials Research期刊。研究人员表示目前大约只有30%的小直径血管移植(直径小于6 mm)，但超过20%的支架因为动脉壁增厚或阻塞而需要更换，虽然在几年前已开发出药物涂料型支架(drug-coated stents)来克服动脉再阻塞(restenosis)的问题，但最近也出现有血块凝结的情况发生。
健康的血管内壁有一层薄的内皮细胞(endothelium)，外围由较厚的平滑肌细胞环绕以组成动脉壁，当然在内壁还有一些由胶原蛋白(collagen)及弹性蛋白(elastin)所组成的奈米级结构，这与大部份由微米级结构组成的移植物形成强烈的对比。Thomas Webster及Karen Haberstroh两位教授想到也许能利用身体的结构将外来的材质融入，于是他们试图去找寻能被身体接受的材质。
当研究人员将移植物的表面材质改成奈米级后，就与内皮细胞的天然结构较为接近，他们发现内皮细胞很快的就在移植物的表面生长出来并掩盖住移植物，避免平滑肌细胞在移植物上过度生长。当内皮细胞长出整齐的一层后，便开始产生胶原蛋白及弹性蛋白。Webster及Haberstroh接下来将在动物试验中测试奈米结构的移植物，是否也能让内皮细胞快速的生长，并让移植物融入身体中，以避免引发免疫反应以及能更长效的使用这些移植物。
(资料来源 : Bio.com)
英文原文：
Nanotextured Implant Materials: Blending In, Not Fighting Back
04/11/07 -- Biomedical engineers are constantly coming up with ways to repair the human body, replacing defective and worn out parts with plastic, titanium, and ceramic substitutes ? but the body does not always accept such substitutes seamlessly. Engineers from Brown and Purdue universities have found that simply changing the surface texture of implants can dramatically change the way cells colonize a wide variety of materials.
Two recent experiments have focused on the materials used in stents ? those springy little cylinders that hold open once-clogged arteries ? and artificial blood vessels. Currently only about 30 percent of small diameter blood vessel grafts (less than 6 mm diameter) last more than five years, and up to 20 percent of stents need to be replaced because the artery walls thicken in and around them in a process known as restenosis. Drug-coated stents were introduced years ago as one way to combat this problem, but concerns have surfaced recently about increased clotting.
Instead of using chemistry to fight the body?s response to such foreign materials, Thomas Webster, an associate professor of engineering, and Karen Haberstroh, an assistant professor of engineering, thought maybe they could use physical structure to allow the foreign materials to blend in better. ?What we?re trying to do is fundamentally different,? says Webster. ?We?re trying to find materials that the body accepts, rather than develop drugs or develop materials that will kill a cell ? no matter if it kills a bad cell or a good cell. We?re trying to find materials that accept good cells, as opposed to killing off bad cells.?
Normal healthy blood vessels have a thin lining of specialized cells called the endothelium, surrounded by a thicker layer of smooth muscle cells that make up the arterial wall. The proteins collagen and elastin make up much of this lining and create a texture of fine nanoscale bumps on the inside of the blood vessel. This contrasts strongly with most of the materials used in implants, which have microscale texture, but are nearly smooth at the nanoscale.
