Doctors have found a way to use 3D printing technology to design human skin grafts in the lab that have been shown to heal wounds faster than traditional grafts.
Skin grafts are done when a person has suffered severe burns or ulcers and after surgery to remove the cancer. They typically require surgeons to remove skin from an undamaged part of the body and apply it to wounds.
Grafts that come from the patient or a deceased donor are often temporary or leave unattractive scars, but scientists at Wake Forest University in North Carolina have bioengineered a near-perfect replica of human skin for the first time to help regenerate meat in the most serious cases. wounds.
The bioprinted skin, tested on mice and pigs, was made using human skin cells designed to be used as ink for a 3D printer-like device. The printer produced thick human-like skin that, when transplanted, effectively formed new blood vessels and helped it regenerate and restore its structure.
Skin is one of the most commonly transplanted organs in the US, and an estimated 160,000 grafts are performed each year. But the current standard for grafts has serious drawbacks, including a limited supply of healthy tissue that can be transplanted, cost and unattractive scars.
Bioprinted skin was grafted onto mice wounds and followed for 90 days, along with a control that received a hydrogel graft and a group that received traditional wound dressings and nothing else. Bioprinted skin grafts helped wounds heal by sending healing skin cells to the wound site instead of pulling the skin tightly together (shrinkage).
To date it has not been possible to create full thickness skin with a bioprinter. If scaled up properly, the technology could help 160,000 people who need skin grafts annually
Wake Forest researchers developed skin in the laboratory that mimicked the biological composition of human skin using six types of human skin cells: epidermal keratinocytes, melanocytes, dermal fibroblasts, dermal follicle papilla cells, dermal microvascular endothelial cells, and adipocytes.
The cells were placed in vials of a specific type of ink used to print biological materials such as organ tissue.
That ink was then used to create a three-by-three-centimeter patch of skin that consisted of the three layers that make up healthy human skin: the epidermis, dermis, and hypodermis.
The three layers together constitute what is known as “full-thickness” skin, and creating it using 3D printing has been impossible until now, the researchers said.
Using six different human cells to develop the skin patches to be used in mice was also crucial in ensuring that the printed graft worked in the same way that natural human skin does when healing wounds.
The researchers said that a shortcoming of previous efforts to develop bioprinted skin was that they contained only two types of cells.
The scientists conducted a similar proof-of-concept experiment in four pigs using four different types of human cells to validate their theory that bioprinting full-thickness skin grafts in a laboratory could be applied to real wounds.
The researchers tested their bioprinted skin on four mice, four others received a control treatment without the bioprinted skin graft, and the final four received a standard bandage.
Photographs of the healing process were taken every week for three weeks. By day 14, the wounds in the mice that were covered with bioprinted skin were completely closed.
At the same time, mice that received the control graft or traditional bandages had their wounds only 64 percent closed.
The human cells used in the skin grafts helped accelerate the migration of epithelial cells to the wound site, the quintessential healing marker known as epithelialization.
Approximately 160,000 skin graft procedures are performed each year in the U.S. This can be challenging, as doctors may not be able to remove the amount of healthy skin needed from one part of a person to repair a wound in another part of the body. Grafts can also go horribly wrong, possibly leading to infection and amputation.
Mice that received bioprinted skin grafts had the fastest healing period compared to other groups. Researchers attribute this to bioprinting’s unique ability to deliver healing cells to the wound site, helping the wound heal cleanly without limiting mobility in the surrounding skin area.
The wounds in the mice that underwent the bioprinted skin grafts also showed signs of forming distinct patterns of human-like ridges and grooves that join the layers of skin. This was notable because normal mouse skin has a very different flat, thin appearance.
The scientists also created full-thickness skin wounds on laboratory pigs. Like the mice, some pigs received a control skin graft, the newly designed bioprinted skin graft, or a traditional wound dressing with bandages without any additional graft. Their healing status was checked twice a week for 28 days.
All pigs, regardless of the treatment they received, saw their wounds completely closed by day 28. However, one important difference was that the pigs that received the bioprinted graft saw their wounds heal through epithelialization rather than contraction, which pushes the surrounding tissues inward. leading to the formation of an unattractive scar.
The epithelialization process also typically lends itself to faster healing and a lower risk of losing mobility due to tight skin, as well as less scarring.
Dr. Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine and co-author of the study, said, “Comprehensive skin healing is a major clinical challenge affecting millions of people worldwide, with limited options.”
“These results show that bioengineering full-thickness human skin is possible and promotes faster healing and more natural-looking results.”
