Tissue regeneration is the process of regrowing or replacing damaged or diseased tissue in order to restore or repair it. The need for tissue regeneration is spurred by hereditary disorders, deformities, and disease-induced tissue damage. Tissue engineering is a technique for preserving, restoring, and improving the function of wounded tissue. By rebuilding damaged organs such as the kidneys, the tissue regeneration process increases a patient's life expectancy. Regenerative medicine has the ability to end the current organ donor shortage; for example, tissue reengineered skin is extremely useful for skin replacement, burn wounds, and ulcers that affect the leg and foot.