Tissue engineering in wound repair: the three "R"s--repair, replace, regenerate

Horses are predisposed to traumatic wounds that can be labor intensive and expensive to manage. Skin has a considerable potential for efficient and functional repair however, while cutaneous repair is a regenerative process in the fetus, this capability declines in late gestation as inflammation and scarring alter the outcome of healing. The historical gold standard for replacement of lost skin is the autologous skin graft. However, the horse's lack of redundant donor skin limits the practicality of full-thickness grafting to smaller wounds; moreover, graft failure is relatively common in equine patients as a result of infection, inflammation, fluid accumulation beneath the graft, and motion. Tissue engineering has emerged as an interdisciplinary field with the aim to regenerate new biological material for replacing diseased or damaged tissues or organs. In the case of skin, the ultimate goal is to rapidly create a construct that effects the complete regeneration of functional skin, including all its layers and appendages. Moreover, an operational vascular and nervous network, with scar-free integration within the surrounding host tissue, is desirable. For this to be achieved, not only is an appropriate source of cells required, but also a scaffold designed from natural or synthetic polymers. The newly created tissue might finally meet the numerous needs and expectations of practitioners and surgeons managing a catastrophic wound in a horse.