Advances in 3D printing technology play significant roles in medical development. Because 3D-printed custom prosthetics are significantly less expensive and faster to fabricate than conventional aids, for example, more families can afford to replace prosthetics for growing children. We’ve written about 3D-printed bionic eyes, skin with integrated sensors, and customized compound pharmaceuticals. While 3D printing can create relatively homogeneous components, it remains a challenge to build items with complex structures with different types of components.

Researchers at the Rensselaer Polytechnic Institute Center for Biotechnology and Interdisciplinary Studies have moved 3D printing further down the development path with an application that made me sit up straighter in my chair. First published in Tissue Engineering Part A, the RPI team printed a two-layer an implantable, multi-layered vascularized bioengineered skin graft. The greatest advantage of the RPI living skin is the ability to inosculate, that is, to connect or join with blood vessels in adjacent skin to allow blood flow.

Current clinical skin graft materials don’t integrate with host cells and eventually fall off, according to RPI’s Pankaj Karande, associate professor of chemical and biological engineering. This is due to a lack of a blood supply to deliver nutrients to the graft.

There are two bio-inks used in the breakthrough RPI process. The first bioink layer contains the dermis which is the lower layer of skin. The ink is a blend of human foreskin fibroblasts, human endothelial cells, and human placental pericytes all suspended in a rat tail collagen. This mix is able to create the vascular structures required to deliver blood to the skin to maintain it. In experiments with rats, this material was able to connect to the existing blood vessels.

The outer layer of the skin is the epidermis layer and it is printed on the dermis with a bio-ink containing human foreskin keratinocytes.

The recipe for the dermis, reminiscent though it may be of the witches’ song in Macbeth, is the magic of the RPI development. Additional research is required before this will become a practical treatment. For example, there will likely need to be a way to incorporate donor cells in the bio-inks so that the living graft is not rejected by the patient’s immune system.