Tissue regeneration is the process of regrowing or replacing damaged or diseased tissue to restore or repair it. Congenital disorders, abnormalities, and disease-induced tissue damage all increase the need for tissue regeneration. Tissue engineering is a technique for preserving, restoring, and improving the function of damaged tissue. By rebuilding damaged organs, such as the kidneys, the tissue regeneration process enhances a patient's life expectancy. Regenerative medicine can end the current organ donor shortage; for example, tissue reengineered skin is beneficial for skin replacement, burn wounds, and ulcers that affect the leg and foot.