The processes that contribute to organ regeneration involve stimulating growth in specific cells. By studying the regenerative abilities of certain animals, researchers obtain a better understanding of what human bodies require to repair or regrow tissue. Regenerative medicine research has revealed the role cytokines, growth factors, stem cells, and other factors that play a role in tissue regeneration.
Since the 18th century, scientists have marveled at the unusual ability of certain animals to undergo cell regeneration. Newts can regrow a severed limb, and salamanders can replace a missing tail. Some species of fish can regrow a damaged fin. A new planaria worm will grow from each piece of a dissected planaria worm.
Three factors contribute to organ regeneration in animals. Organ and other tissue cells that normally do not reproduce will do so during injury or illness. In certain animals, cells transform from one type of tissue into another. Stem cells are also involved in these regenerative processes. In comparison, human bodies have the capacity to heal, though not without scarring.
Once scarring occurs, cell growth generally ceases. Researchers discovered a means of inhibiting this process by developing a substance called extracellular matrix, one type of which contains connective tissue, pig bladder cells, and proteins. When applied to the severed finger of a patient, the substance prevented scarring and triggered reproduction of various types of cells in the digit. In about four weeks, the patient reportedly regrew the entire portion of the severed finger.
Organ regeneration usually begins with placing specific tissue cells, along with a growth medium, into petri dishes. Tissue that develops from the cells is placed over a specially designed foundation. Depending on the type of regenerated tissue, mature growth usually occurs in about eight weeks. Surgeons typically implant the entire specimen into the patient's body, including the foundation scaffold. The scaffold generally dissolves and the new tissue functions without the possibility of rejection.
Using this technique for tissue regeneration, physicians have successfully grown dozens of animal and human tissue types. Blood vessels, connective and muscle tissue, as well as bladders, are among the regenerative advancements patients receive surgically. These laboratory grown replacements all began as cells donated by the patients themselves.
In addition to the benefit of not having to take antirejection medications, natural organ regeneration increases the number of options for patients on transplant lists. The number of patients requiring donated organs generally exceeds the number of available organs. Advancements in regenerative medicine will allow patients the opportunity to grow their own body parts.