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Artificial skin-like systems can be used in place of animals to test pharmaceuticals and cosmetics or to model how wounds heal. But commercially available human skin equivalents (HSEs), typically last about one week before degradation begins. A new matrix, however, could enable longer-terms studies of human skin responses over weeks or even months and be tuned to match specific cell or skin requirements.
Materialstoday.com reports that researchers have found a way to use silk to make artificial skin last longer. The report quotes a study in Biomaterials (2018) by a team from Tufts University and Carnegie Mellon University that combined collagen gels with silk-derived proteins to create a silk-collagen composite system that can support and cultivate skin equivalents, including nerves, without degrading significantly.
“[Our] hybrid silk-collagen matrix supports ameliorate the problem with collagen contraction over time, which can limit in vitro cell cultures and limit their utility to acute versus chronic studies,” says David L. Kaplan, who led the research. “The silk provides a stable framework or scaffolding that does not significantly change in morphology over time, holding the collagen in an open porous state to support cell culture.”
The team first created a composite biomaterial matrix from a mixture of extracted silk proteins and collagen using an enzyme-driven free radical cross-linking method. Important cell types (including adipocytes, pre-adipocytes, endothelial cells, smooth muscle perocytes, and immune cells) are then introduced into the matrix, along with human-induced neural stem cell (hiNSCs), which differentiate into neurons within a week.
The silk prevents the contraction of the collagen by stabilizing the three-dimensional porous matrix, which in turn supports oxygen and nutrient transport to cells. Moreover, the mechanical properties of the silk-collagen composite can be tuned to resemble those of native human skin.
Kaplan believes that the silk-collagen matrix, which is fully biodegradable and made from FDA-approved components, could be suitable for in vitro testing and research immediately and, in the longer term after full FDA approval, for in vivo applications such as treating burns, chronic wounds, or trauma injuries.
“We are looking for corporate partners to use the system in both these ways,” Kaplan told Materials Today. “For in vitro skin studies related to transport, toxicology, and disease; and animal and then humans studies for in vivo applications.”