Tissue regeneration is the process of renewal and growth to repair or replace tissue that is damaged or suffers from a disease. There are some human organs and tissues that regenerate rather than simply scar, as a result of injury. These include the liver, fingertips, and endometrium. Some human organs, e.g. liver and skin, also regenerate when they are damaged. Studying regeneration in other species will help us understand how the human body heals and repairs itself. This could help researchers develop regenerative medicines to help the human body more fully heal. Smooth muscle tissue can regenerate from a type of stem cell called a pericyte, which is found in some small blood vessels. Pericytes allow smooth muscle cells to regenerate and repair much more readily than skeletal and cardiac muscle tissue. Humans have limited regeneration ability, all the organ tissues can regrow, but it is very limited except the liver. Studies can find new methods to deal with regeneration. Recently, scientists are investigating the genes and factors which are active during regeneration.