French scientists have unveiled a new medical procedure to create a “human textile” from someone’s own skin. The body’s immune system is less likely to reject the patient’s native biological material after a tissue graft – or so the thinking goes.
Researchers at the French National Institute of Health and Medical Research in Bordeaux said:
“These human textiles offer a unique level of biocompatibility and represent a new generation of completely biological tissue-engineered products.”
If all goes as planned, surgeons will be able to close wounds or implant skin grafts from the patient’s tissue.
First, thin sheets of human skin cells were cut into long, fine strips. The stringy cells were then woven together to make a tenuous, translucent substance that resembles gooey yarn. The yarn can be assembled into all sorts of configurations.
Nicholas L’Heureux, the lead researcher, explained the many uses of this human cell-based string:
“We can sew pouches, create tubes, valves, and perforated membranes. With the yarn, any textile approach is feasible: knitting, braiding, weaving, even crocheting.”
So far, the bio-yarn has passed tests on a lab rat and a sheep. The rat healed well two weeks after wounds were sutured with the new material. A skin graft fashioned on a custom-made loom patched a sheep’s artery and stopped it from leaking.
One sheet of human skin cells is called a cell-assembled extracellular matrix (CAM). CAMs are completely natural, biological, and hardy. They can be made in large quantities for clinical applications using normal, adult, human fibroblasts – the main active cells of connective tissue – with a lower chance of producing inflammation.
The French bioengineers had developed the biomaterial CAMs as human tissue-based blood vessels in a previous project. They wanted a good clinical alternative in native vein or artery for vascular surgery to artificial, allergy-producing or foreign vessels that had a high rate of patient intolerance (rejection, thrombosis, chronic inflammation, and poor mechanical properties).
Their underlying theory was the same: reduce the chance of organ rejection from an immune system response by using biomaterial from the patient being treated. This would reduce or eliminate the need for powerful immunosuppressant drugs post-operatively.
Adult human fibroblasts extracted from skin biopsies were harvested from individuals with advanced cardiovascular disease. The scientists constructed tissue-engineered blood vessels (TEBVs) as arterial bypass grafts in long-term animal studies.
The mechanical properties between TEBVs and human blood vessels are similar. TEBVs, however, include no synthetic or scaffolding from materials originating outside the body (exogenous).
The TEBVs were shown to be stable mechanically and anti-clotting (anti-thrombogenic) for 8 months in laboratory test tubes. Further analysis led the bioengineers to conclude that their tissue-engineered blood vessel can be assembled exclusively from a person’s own cells as a viable alternative to synthetic or other foreign tissue repair solutions.
According to the innovators, “this material can be used as a simple suture to close a wound or can be assembled into fully biological, human, tissue-engineered vascular grafts (TEVG) that have high mechanical strength and are implantable.”
The French bio-developers are optimistic that their invention will be useful to humans, too:
“By combining this truly ‘bio’ material with a textile-based assembly, this original tissue engineering approach is highly versatile and can produce a variety of strong human textiles that can be readily integrated in the body.”
A 33-year-old Frenchman named Franck could have used a TEVG after he arrived at a hospital in critical condition with deep burns from a work accident in September 2016. To reduce the chance of rejection, doctors called in Franck’s twin who donated skin grafts. Because the siblings were genetically identical, Franck’s immune system accepted the new skin as his own.
Maurice Mimoun, a surgeon at the Saint-Louis Hospital in Paris, where the procedure was carried out, said this was not the first twin-on-twin skin transplant but was the first to cover such a large area.
Franck needed about 10 graft surgeries over four-and-a-half months while he was hospitalized before being stepped down to a rehabilitation center.
Normally, skin grafts are harvested from a deceased donor and typically rejected within weeks of the surgery. By that time, the patient’s natural skin often has begun healing.
Franck from France reported mending well after his twin’s skin transplants. Before his job injury, he had been in good health and was a non-smoker, boosting his body’s ability to repair damaged tissue.
For those of us who don’t have a biological twin, home-grown tissue-engineered stitchery may come to the rescue.