New 3D Bioprinting Technique Utilizes Vasculature that Closely Simulates Human Skin

Scientists are making more and more amazing advances in bioprinting—using a type of 3D printing to manufacture biological tissues. Researchers at Rensselaer Polytechnic Institute developed a technique for 3D printing living skin that also has blood vessels. They published their research in the journal Tissue Engineering Part A.

3D printing is also called “addictive manufacturing.” It is a method for making a three-dimensional solid object from a digital file. 3D printing used in industrial applications typically utilizes carbon fiber as a source material. In bioprinting, biological materials, such as single cell suspensions, are used as source materials.

The Rensselaer researchers used living human cells as “bio-inks” and printed them into skin-like structures. The addition to this technique was adding human endothelial cells that line the inside of blood vessels and human pericyte cells, which surround the endothelial cells. These were used with animal collagen and other types of structural cells usually found in a skin graft. Within a few weeks, the cells began communicating and forming vascular structure.

“Right now, whatever is available as a clinical product is more like a fancy Band-Aid,” said Pankaj Karande, an associate professor of chemical and biological engineering and member of the Center for Biotechnology and Interdisciplinary Studies (CBIS). Karande led the research. “It provides some accelerated wound healing, but eventually it just falls off; it never really integrates with the host cells.”

But that doesn’t not appear to be the case with this new approach, because of the functioning vascular system.

“As engineers working to recreate biology, we’ve always appreciated and been aware of the fact that biology is far more complex than the simple systems we make in the lab,” Karande said. “We were pleasantly surprised to find that, once we start approaching that complexity, biology takes over and starts getting closer and closer to what exists in nature.”

Another group of researchers at Yale University grafted the experimental 3D-printed skin onto a mouse model. The skin began to communicate and connect with the mouse’s own blood vessels. Karande noted that this meant there was an actual transfer of blood and nutrients to the graft.

The next step is to advance the skin graft to human clinical use. To do so they need to edit the donor cells using something akin to CRISPR gene editing so the blood vessels won’t be rejected by the patient’s body.

“We are still not at that step, but we are one step closer,” Karande said.

In addition, skin grafts are used with burn patients, who often have damaged nerve and vascular endings. That’s still a way down the road, but this new research is very promising. It is also likely to have more immediate applications for less complex skin graft demands, such as diabetic or pressure ulcers.

“For these patients,” Karande said, “these would be perfect, because 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.”

“This significant development highlights the vast potential of 3D bioprinting in precision medicine, where solutions can be tailored to specific situations and eventually to individuals,” said Deepak Vashishth, the director of CBIS. “This is a perfect example of how engineers at Rensselaer are solving challenges related to human health.”