德国科学家发现，可以用蜘蛛丝培育人类皮肤，这项研究为皮肤移植等医学难题提供了好的解决办法。
蜘蛛侠电影中神奇的蜘蛛丝具有高强度的拉伸和延展性
德国研究人员培育蜘蛛丝的实验前后对比图
皮肤移植是医学界的一个重要课题，皮肤移植片对治愈烧伤病患和其他病患非常重要。比如，美国每年有650万住院病人有褥疮等慢性伤口，仅这项疾病的医疗支出就高达250亿美元。
目前，很多科研团队正在研制人造皮肤以替代从人体自身提取皮肤进行移植。理想的可用于移植的人造皮肤是一种能被身体接受的材料，有皮肤细胞内置于其中来取代受损的组织，随着时间的推移，当长出的新皮肤的柔韧度足以对抗普通皮外伤后，人造皮肤会安全地“隐退”。
德国汉诺威医学院的细胞组织工程师汉娜·文德特表示，迄今所研发材料的柔韧度似乎都不足以完成这个任务。经过一番研究后，她们认为，蜘蛛丝或许能胜任这个任务。
蜘蛛丝是自然界中已知的最坚韧材料，2000多年前，民间就流传着很多关于蜘蛛丝与医疗应用的传说，例如，蜘蛛丝在对抗感染、出血、让伤口愈合等方面都能“有所作为”，另外，蜘蛛丝还可作为人造韧带使用。
蜘蛛丝具有非凡的柔韧度和延展性，这使科学家能通过对其进行简单地处理和变换来制造各种不同类型的移植物。另外，与蚕丝不同的是，蜘蛛丝不会触发人体的排斥反应。
为了测试蜘蛛丝是否有用，文德特和同事首先通过敲打金丝蛛属圆蛛的丝腺让它们吐丝，并将吐出的丝纤维缠绕起来，然后用这些丝线在金属框架上编织出网格，并将人体的皮肤细胞置于网格上进行培养。四天后，皮肤细胞就从角落进入网格内，一周后，皮肤细胞就相互结合在一起。
研究人员发现，如果给予适宜的培育、养分、温度和空气，置于这些网格上的人体皮肤细胞会旺盛地生长，经过35天的培养后，细胞的存活率高达98%。
文德特称，他们能用这种方法将两种主要的皮肤细胞——角蛋白形成细胞和纤维原细胞培育成类似皮肤的表皮（皮肤的最外层结构）和真皮（表皮之下的一层活细胞，包含有毛细血管、神经末梢、汗腺、毛囊）等功能结构。
Artificial Skin Spun from Spider Silk
The secret to creating artificial skin might be spider silk, researchers now suggest.
Skin grafts are vital for treating burn victims and other patients. For instance, chronic wounds such as bedsores in hospitalized patients afflict 6.5 million in the United States alone for estimated costs of $25 billion annually.
Instead of using skin from a body for a graft, scientists are investigating artificial skin. Ideally such a graft would be of a material tolerated by the body, have skin cells embedded within it to replace lost tissue, degrade safely over time as the new skin grows in and be strong enough to withstand all the rigors ordinary skin experiences. Materials investigated until now did not seem strong enough for the task, said tissue engineer Hanna Wendt at Medical School Hannover in Germany.
Now Wendt and her colleagues suggest silk might be up for the job.
Spider silk is the toughest known natural material. Moreover, there is abody of folklore dating back at least 2,000 years regarding the potential medical value of webs — for instance, in fighting infections, stemming bleeding, healing wounds and serving as artificial ligaments.
The extraordinary strength and stretchiness of spider silk "are important factors for easy handling and transfer of many kinds of implants," Wendt said. In addition, unlike silk from silkworms, that from spiders apparently does not trigger the body's rejection reactions.
To test spider silk's usefulness, first Wendt and her colleagues essentially milked golden silk orb-weaver spiders by stroking their silk glands and spooling up the silk fibers that came out. They next wove meshes from this silk onto steel frames. [See images of skin cells growing]
The researchers found that human skin cells placed on these meshes could flourish, given proper nurturing with nutrients, warmth and air. They were able to cultivate the two main skin cell types, keratinocytes and fibroblasts, into tissue-like patterns resembling epidermis, the outermost layer of skin, and dermis, the layer of living tissue below the epidermis that contains blood capillaries, nerve endings, sweat glands, hair follicles and other structures.
"It was impressive to observe how human cells use spider silk," Wendt told LiveScience.
Currently, harvesting large amounts of spider silk for industrial standards is not practical. "I think in the long term, for widespread daily clinical use, synthetic silk fibers providing the same mechanical- and cell culture- properties will be needed," Wendt said. Currently, many research groups are investigating ways to grow synthetic spider silk.
The scientists detailed their findings online July 26 in the journal PLoS ONE.
