生醫(yī)工程人員不斷的想出新的方法以取代現(xiàn)有以塑料,、鈦合金或陶瓷材質(zhì)的醫(yī)療器材,，因為這些材質(zhì)大多不被身體所接受，時間一久就會損壞或老舊,。布朗大學(Brown University)以及普度大學(Purdue University)的研究人員發(fā)現(xiàn),，只要簡單地改變移植器材的表面結(jié)構(gòu)，就能讓體內(nèi)的細胞生長而能預防再阻塞的情況,。
最近有兩份實驗特別針對撐開血管的支架(stents)等材質(zhì)進研究,，分別發(fā)表于Tissue Engineering以及Journal of Biomedical Materials Research期刊。研究人員表示目前大約只有30%的小直徑血管移植(直徑小于6 mm),，但超過20%的支架因為動脈壁增厚或阻塞而需要更換,，雖然在幾年前已開發(fā)出藥物涂料型支架(drug-coated stents)來克服動脈再阻塞(restenosis)的問題，但最近也出現(xiàn)有血塊凝結(jié)的情況發(fā)生,。
健康的血管內(nèi)壁有一層薄的內(nèi)皮細胞(endothelium),，外圍由較厚的平滑肌細胞環(huán)繞以組成動脈壁，當然在內(nèi)壁還有一些由膠原蛋白(collagen)及彈性蛋白(elastin)所組成的奈米級結(jié)構(gòu),，這與大部份由微米級結(jié)構(gòu)組成的移植物形成強烈的對比,。Thomas Webster及Karen Haberstroh兩位教授想到也許能利用身體的結(jié)構(gòu)將外來的材質(zhì)融入，于是他們試圖去找尋能被身體接受的材質(zhì),。
當研究人員將移植物的表面材質(zhì)改成奈米級后,，就與內(nèi)皮細胞的天然結(jié)構(gòu)較為接近，他們發(fā)現(xiàn)內(nèi)皮細胞很快的就在移植物的表面生長出來并掩蓋住移植物,，避免平滑肌細胞在移植物上過度生長,。當內(nèi)皮細胞長出整齊的一層后，便開始產(chǎn)生膠原蛋白及彈性蛋白,。Webster及Haberstroh接下來將在動物試驗中測試奈米結(jié)構(gòu)的移植物,，是否也能讓內(nèi)皮細胞快速的生長，并讓移植物融入身體中,，以避免引發(fā)免疫反應以及能更長效的使用這些移植物,。
(資料來源 : 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.
