Bioprinting directly onto the body seems a logical evolution of the state of the art in this part of the field, given the emerging ability to bioprint full thickness skin, or at least a living structure very close to that. It is interesting to consider how bioprinting in situ could be made to work for internal organs. We might envisage something akin to keyhole surgery with a machine-guided printing head. The easier initial applications might include printing a patch of tissue directly onto the heart, akin to the present development of heart patches that are grown outside the body and then transplanted. The Lygenesis approach of liver or thymus organoids inside lymph nodes might also be amenable to this sort of evolution, given suitable printing hardware.

Imagine a day when a bioprinter filled with a patient's own cells can be wheeled right to the bedside to treat large wounds or burns by printing skin, layer by layer, to begin the healing process. That day is not far off. Scientists have created such a mobile skin bioprinting system - the first of its kind - that allows bi-layered skin to be printed directly into a wound. Affecting millions of Americans, chronic, large or non-healing wounds such as diabetic pressure ulcers are especially costly because they often require multiple treatments.

The major skin cells - dermal fibroblasts and epidermal keratinocytes - are easily isolated from a small biopsy of uninjured tissue and expanded. Fibroblasts are cells that synthesize the extracellular matrix and collagen that play a critical role in wound healing while keratinocytes are the predominant cells found in the epidermis, the outermost layer of the skin. The cells are mixed into a hydrogel and placed into the bioprinter. Integrated imaging technology involving a device that scans the wound, feeds the data into the software to tell the print heads which cells to deliver exactly where in the wound layer by layer. The bioprinter deposits the cells directly into the wound, replicating the layered skin structure, and accelerating the formation of normal skin structure and function.

The researchers demonstrated proof-of-concept of the system by printing skin directly onto pre-clinical models. The next step is to conduct a clinical trial in humans. "The technology has the potential to eliminate the need for painful skin grafts that cause further disfigurement for patients suffering from large wounds or burns."