Live skin can now be printed in 3D, including blood vessels

In order to treat the severely burned and for the treatment of various diseases affecting the skin, the development of artificial skin grafts has become a field of future research, but so far, the absence of functional vascular system in the grafts is a significant barrier to their integration. To remedy this problem, researchers at the Rensselaer Polytechnic Institute have developed a way to 3D-print "living skin" by incorporating blood vessels.

" Right now, all that is available as a clinical (transplant) product is more like a sophisticated dressing ," said Pankaj Karande, associate professor of chemical and biological engineering and a member of the Center for Biotechnology and Biotechnology. Interdisciplinary Studies (CBIS), which led this research project at the Rensselaer Polytechnic Institute (USA). " They allow accelerated healing of wounds, but they eventually fall; they never really integrate with host cells  . "

The absence of a functional vascular system in skin grafts constitutes a major obstacle to this integration. Karande has been trying to meet this challenge for several years. He has published previously one of the first articles showing that it was possible, from two types of living human cells, to turn them into "bio-inks" to print skin with more natural biological properties. Since then, he and his team have been working with researchers at the Yale School of Medicine to incorporate blood vessels into artificial grafts.

Their new design, detailed in a document published last week in the journal Tissue Engineering Part A , represents an important step in the creation of artificial grafts with properties close to those of human skin.

Allow cellular communication to interconnect vascular structures

In their article, the researchers show that if they add some key elements, the cells begin to communicate and form a biologically relevant vascular structure within a few weeks. These key elements include: human endothelial cells (keratinocytes) (lining the inside of blood vessels), human pericytes (which surround endothelial cells) as well as animal collagen and other structural cells commonly found in grafts skin.

" As engineers working on the reenactment of biology, we have always appreciated and understood that biology is much more complex than the simple systems we make in the lab,  " said Karande. " We were pleasantly surprised to see that as soon as we tackle this complexity, biology takes over and begins to get closer to what exists in nature  ."

Once the Yale team grafted the new skin onto a special type of mouse, the blood vessels printed by the Rensselaer team began to communicate and connect with the natural vessels of the mouse.

" This is extremely important because we know there is actually a transfer of blood and nutrients to the graft, which keeps it alive,  " said Karande.

Make the graft compatible using the CRISPR genetic editing technique

In order to make artificial skin usable at the clinical level, researchers must be able to edit donor cells using CRISPR technology, so that vessels can integrate and be accepted by the patient's body. " We're not at this point yet, but we're getting closer ," Karande said.

" This significant development (presented in the study) highlights the vast potential of 3D bioimprinting in precision medicine, where solutions can be tailored to specific situations and ultimately to individuals,  " said Deepak Vashishth, director of CBIS. " This is a perfect example of how Rensselaer's engineers solve human health problems  ."

Karande said more studies will be needed to address the challenges associated with burns, including the loss of nerve and vascular endings. But the plugins created by his team will encourage other researchers to help people with more discreet problems, such as diabetes or pressure ulcers.

" For these patients, it would be perfect because ulcers usually appear in separate parts of the body and can be treated with smaller pieces of skin,  " said Karande. " Wound healing usually takes longer in diabetic patients, which could also help speed up this process  ."

In the video below, Karande presents her design:


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