Skin bio-printing: the concept
Wake Forest researchers developed a clinical prototype of the skin bio-printer and tested it in several animal studies. Today’s prototype is mobile, and would allow clinicians to wheel it to a patient’s hospital bed and print directly on the wound.
Initial animal studies for skin bio-printing were in nude mice, before researchers moved to an incisional wound model in pigs.
In the pig study, scientists made incisional wounds on the pigs’ backs. Each was 10 cm by 10 cm, or 100 cm2. They left one of the wounds untreated, using standard care of bandaging. In the second wound, they used a matrix, or hydrogel, which included fibrin and collagen. In the third wound, they used that same hydrogel with the culture expanded cells and applied two different layers of cells.
“We would add the dermal fibroblasts to the fibrin collagen hydrogel and print that first; then, we would print the keratinocytes in the hydrogel over top of that first layer,” he says.
By “printing,” Dr. Jackson means applying air pressure, which pushes the hydrogel and cells out of the print nozzle.
The skin cells came from a small biopsy of an uninjured area on the pig. They isolated two cell types —keratinocytes, then, dermal fibroblasts — then, expanded the cell types in culture to later bio print them directly into the created wounds.
“For our technique, we actually take small biopsies of skin and expand them in culture, so you have to do that expansion in a special facility under very strict conditions because you’re manipulating the cells,” Dr. Jackson says. “Then we take the cells and place them into our bio printer. In conjunction with the skin bio printer, we have a laser scanner. We scan the wound, which gives a 3D rendering of the wound. That information is processed by the computer and controls the bio printer to fill the wound.”
The scanner determines the number of cells needed for the deeper and shallower wound areas, he says.
The researchers found that the bio-printed cells enhanced the healing of the wound by three to four weeks, when compared to untreated or the matrix treated wounds. A manuscript is under review describing the data from these studies, Dr. Jackson says.