Skin with blood and lymphatic capillaries grown

Conventional skin grafting involves healthy skin being removed from one area of the body to replace damaged skin. Only small areas of skin can be removed from the patient because it creates a new wound. Skin can also be engineered for grafting, which involves taking a patient's cells and growing skin from them. This is then used to replace damaged skin. So far, engineered skin has not contained blood or lymphatic capillaries, sebaceous glands, pigmentation, hair follicles or nerves.

But the research team, from the University of Zurich and the University Children's Hospital Zurich, has discovered a way to create skin that contains fully functional blood and lymphatic capillaries.

Lymphatic capillaries are small vessels located in the spaces between all cells in the body, except the tissues of the central nervous system and non-vascular tissue. The main function of the lymphatic capillaries is to drain excess fluid that has been excreted from tissues following a wound. This helps the wound healing process. Blood capillaries are the smallest of all blood vessels in the body that connect the veins and the arteries.

For the study, the researchers isolated blood and lymphatic capillary cells from samples of human skin. Using these cells, they were able to engineer a skin graft similar to full-thickness skin that contains fully functioning blood and lymphatic capillaries. The research team found that the lymphatic capillary cells instinctively arranged themselves into lymphatic capillaries and had the same characteristics as lymphatic vessels. When the investigators put this engineered skin to the test in preclinical trials, they found that both the blood and lymphatic capillaries were able to connect with those of laboratory animals.

What's novel in this is that the lymphatic capillaries collected and transported tissue fluid; hence they were functional. It can be assumed that skin grafts with lymphatic and blood capillaries will, in future, both prevent the accumulation of tissue fluid and ensure rapid blood supply of the graft. The investigators say the first clinical application of these skin grafts is already planned to take place this year. But they note that approval still has to be achieved for testing with blood and lymphatic capillaries, and therefore the skin grafts will go ahead without them.