Burn care has improved a lot over the last few decades, but large burns still take a long time to heal and the patient often has to stay in the hospital for a long time. Large burns also often cause significant scarring and disability. This is because it is hard for the body to repair large areas of skin injured by burn.
The body’s natural repair process involves special cells in the skin whose job it is to form new skin. These skin stem cells work together with other types of cell that form new blood vessels to feed the newly-formed skin and that control inflammation. However, deep burns destroy these skin stem cells and helper cells and, as a result, normal healing can’t occur. This can result in scarring where the wound becomes covered with stiff, hard, itchy, discolored scar rather than with healthy skin. To avoid or minimize scarring, surgeons take a very thin layer of healthy skin from an uninjured part of the patient and place it over the area with the deep burn. This skin graft brings with it new stem cells that can form new, healthy skin.
Image of a healing wound showing the different layers of the skin
An example of scarring after burn
Sometimes the skin graft is prepared in a way that allows a relatively small amount of healthy skin to be used to treat a much larger area of burn. This process is called “meshing”. In meshing tiny slits are made in the graft so that it can be spread or expanded to cover a larger area. Skin stem cells within the graft then heal the tiny expanded slits to create healthy skin. But, skin stem cells are only part of the solution. Growth of healthy, normal skin requires helper cells that create new blood vessels to feed the new skin and that control inflammation.
A meshed skin graft ready to be applied to a burn wound
Fat Tissue as a Source of Helper Cells for Regenerative Medicine
It turns out that fat tissue, also known as adipose, may be a particularly good source of these helper cells. This is likely because fat is the one tissue in the adult human body that can undergo substantial increases and decreases in size (as a person gains and loses weight). Fat can do this because it contains helper cells with special properties in and around its blood vessels. These cells are called Adipose-Derived Regenerative Cells (ADRCs).
For the past several years Cytori, the company sponsoring the RELIEF Trial, has been studying the ability of ADRCs to help heal burn wounds and meshed skin grafts. Studies in animals performed by Cytori scientists have shown that giving an animal its own ADRCs through a vein can improve healing of skin grafts and skin graft donor sites following burn injury. Based on this work and a large body of other preclinical and clinical research, the US Food and Drug Administration has approved the company to perform a clinical trial using ADRCs in patients with burns. This trial is known as the RELIEF clinical trial.
The RELIEF clinical trial will test the safety of using ADRCs to help heal burn wounds and whether this would be a practical way to treat burns. This knowledge may help future burn patients, including members of our Armed Forces burned by improvised explosive devices or other enemy weapons.