Left: the silk mesh 1 day after being seeded with fibroblast cells. Right: 4 days after seeding.
What’s the News: People have long known that spider silk has many practical uses, even in the medical field; Ancient Greeks, for example, employed the strong, flexible fiber as bandages
. But the clinical uses of spider silk may stretch beyond that: scientists may someday be able to use the silk to help create artificial skin, according to new research out of the Hannover Medical School in Germany. In the study, published recently in the journal PLoS One
, researchers successfully grew tissue-like skin on a mesh frame of silk harvested from golden silk orb-weaver spiders
. What’s the Context:
Adult skin is made up of two tissue layers: the epidermis and dermis. The epidermis is the outermost layer of the skin, which provides a sort of barrier against the environment. Below this is the dermis, a layer of tissue that provides strength, nourishment, and resilience to the epidermis.
Effective artificial skin (for patients that need skin grafts, such as burn victims) needs to replace both layers of skin and be able to degrade over time as new skin grows in. Recent techniques have created matrices for artificial skin from collagen and synthetic polymers like poly(lactic-co-glycolic acid), but these materials have a low mechanical strength and don’t degrade quick enough, according to the researchers of the current study. Spider silk, on the other hand, is strong, biodegradable, and does not produce a harmful immune response.
How the Heck:
Tissue engineer Hanna Wendt and her team began by harvesting silk from the spiders—they stroked the arachnids’ silk glands and spooled the silk fibers that came out. They weaved the dragline silk onto a rectangular steel frame, creating a thin, easy-to-handle scaffold that they then sterilized with steam.
With the right amount of nutrients, warmth, and air, the researchers grew tissue-like skin onto the silk weave. They started by seeding their mesh constructs with fibroblast cells, which produce the extracellular matrix of the dermis. After cultivating the fibroblasts for two weeks, the team added in keratinocytes, the predominate cells of the epidermis. The cells eventually created a bilayer skin model, with tissue-like patterns resembling epidermis and dermis.
Not So Fast:
The current setup is not ready for widespread medical use. One major issue is the difficulty of harvesting the necessary amounts of spider silk from actual spiders. "Synthetic silk fibers providing the same mechanical- and cell culture properties will be needed," Wendt told LiveScience.
Another problem is the use of a stainless steel frame, which has a fixed structure and cannot be absorbed by the body. As the researchers point out in their paper, further experiments could yield “an absorbable frame or a knitted spider silk matrix” to fix this issue.
Image courtesy of H. Wendt,