Everyone’s skin is made up of several cell types, including but not limited to keratinocytes, melanocytes, fibroblasts, endothelial cells, and adipocytes, an these together make up the epidermis, dermis, and hypodermis. Our skin is our body’s largest organ and our first line of defense from any unwanted debris/viruses/infections that come from the outside world. Injuries to the skin pose a risk to our immune health. however, some people see the skin more as an ornament, a sign of beauty, youth, and perfection. Thus, injuries that put this idea of beauty at risk become more than just a medical issue, they become a cosmetics issue.

In the event of severe injury where a skin transplant may be needed, there are challenges with both site shortage and scarring. Tissue engineering of skin is an attempt to reduce or maybe eliminate both of these issues.

The greatest demonstrated need for skin substitutes comes from patients who have burn injuries and those with chronic open wounds. Current technology has 3 different types of skin substitutes, epidermal layer, dermal supportive structure, and a combined epidermal and dermal layer. These substitutes can be both acellular or have a cellular component to improve the uptake and function.

Many of these substitutes are made up of natural materials, such as bovine collagen . For example, Apligraf makes a dermoepidermal substitute that is made up of a bovine collagen type I matrix which is then seeded with allogeneic keratinocytes and fibroblasts cultured from neonatal foreskins. Another company, Orcel, makes a similar bovine collagen sponge matrix, seeded with neonatal foreskin derived keratinocytes and fibroblasts, but this sponge matrix is non-porous and gel coated on its epidermal side.

However, there are some issues that need to be addressed to make this skin substitutes even better. For example, there are vascularization issues with skin grafts that are more than 1.00 mm in thickness, as the blood vessels cannot grow quick enough to adequately nourish the overlaying epidermal layer. By prevascularizing skin grafts, this could be avoided, and prevascularized grafts could also benefit patients who require grafts in poorly vascularized wound beds. In this figure, we see the improvements of skin substitutes and the ways the human body interacts. in A, the red staining shows Cytokeratin 19-positive basal human cells that are indicative of a epidermal homeostasis located only in the well-defined stratum basale, and stained in green are human dermal fibroblasts that are successfully recognized. In B, the white arrows point to supranuclear melanin caps that are able to protect DNA from harmful UV lights, and these formed in an animal transplantation assay of a skin substitute.

Having the options of cellular and acellular skin grafts are promising because they can be cellularized with native cells, reducing risk of rejection. Further, an issue is shortage of actual transplantable tissue. By continuing to successfully develop skin grafts, this shortage can be eliminated.

Finally, the nature of these skin substitutes coming from natural materials and utilizing other biomaterials (ie hydrogel coatings), we see the marriage across disciplines that is working hard to solve issues that we face on an everyday basis, and also finding ways to help victims of tragic events feel themselves again. This could continue to expand to help victims of crimes, such as acid attacks, that permanently damage their skin and ultimately their confidence. It can help victims of tragic accidents, such as fires, as well.