Often misused synonymously with cosmetic surgery, plastic surgery refers to procedures used to repair and reconstruct missing or damaged skin. This can certainly have cosmetic purposes, but by and large the main aim of plastic surgery is to restore the function of tissues and skin to as close to normal as possible.
One of the main plastic surgery techniques is a skin graft, where healthy skin from an unaffected area of the body is removed and used to replace lost or damaged skin. These can be divided into split thickness skin grafts and full thickness skin grafts.
In split thickness grafts, a paper-thin layer of skin is shaved from an area like the buttock, thigh or calf and placed onto a donor area. A full thickness skin graft is where all three skin layers are removed, usually from an area like the neck, upper arm or groin.
Of course, it’s not as easy as cut and paste. Skin grafts can be rejected, particularly if a patient smokes or has circulatory issues affecting the transplant area. If this happens, they may well need a second skin graft, creating further wounds on their body.
Now, 3D printing may offer an alternative.
Let’s get the blood flowing
Researchers at Rensselaer Polytechnic Institute in New York have developed a way to 3D-print living skin, complete with blood vessels. This 3D-printed skin could allow patients to undergo skin grafts without having to suffer secondary wounds to their body.
Skin has been 3D-printed before, but has lacked a functioning vascular system needed for grafting surgeries.
In a November 2019 statement, Rensselaer Polytechnic Institute associate professor Pankaj Karande said: “Right now, whatever is available as a clinical product is more like a fancy Band-Aid. It provides some accelerated wound healing, but eventually it just falls off; it never really integrates with the host cells.”
The graft is formed through two bio-inks. The first is made using human foreskin dermal fibroblasts (FBs), human endothelial cells (ECs) derived from cord blood, human endothelial colony-forming cells (HECFCs) and human placental pericyte cells (PCs) suspended in rat tail type I collagen to form a dermis. A second bio-ink containing human foreskin keratinocytes (KCs) is then printed to form an epidermis.
The KCs replicate and mature to form a multi-layered barrier, while the ECs and PCs self-assemble into interconnected microvascular networks. The cells start communicating and forming a biologically relevant structure within a few weeks.
Thus far, the skin has been grafted on to the backs of immunodeficient mice. The blood vessels of the 3D-printed skin were seen to communicate and connect with the blood vessels of the mice, transferring blood and nutrients. This was vital to prove the future efficacy of the technology, as it let the research team know that the 3D-printed skin would actually stay alive once grafted.
More work needed
A fair bit of work is needed to take this 3D-printed skin to the clinic and start grafting it to wounded humans. To make it usable on a clinical level the researchers will need to edit the donor cells, potentially using CRISPR technology, so that the blood vessels will integrate and be accepted by a patient’s body.
If it makes it into the clinic, the 3D-printed skin is also more likely to reach patients with diabetic and pressure ulcers than it is burn victims who face nerve and vascular damage.
Karande said: “Ulcers usually appear at distinct locations on the body and can be addressed with smaller pieces of skin. Wound healing typically takes longer in diabetic patients, and this could also help to accelerate that process.”
Skin grafts are a relatively simple procedure, but there’s always the risk of donor site infection, which can be especially concerning for patients in poorer health. There’s also the aesthetic side of the coin, as graft sites often retain a ‘meshed’ appearance after healing which many patients want to avoid on more prominent areas of the body – especially the face. Skin grafts have also been known to grow hair, and the tone of the donor skin may not match the site it is transferred to.
By tailor-making 3D-printed, living skin for these operations, the risk of complications is drastically reduced and aesthetic concerns can be worked around with more finesse. If artificial skin grafts are to be the future of this kind of surgery, then the research coming out of Rensselaer Polytechnic is definitely something to keep an eye on.