Healing: Encyclopedia II - Healing - Healing by regeneration

Healing - Healing by regeneration

In order for an injury to be healed by regeneration, the cell type that was destroyed must be able to replicate. Most cells have this ability, although it is believed that cardiac muscle cells and neurons are two important exceptions.

Cells also need a collagen framework along which to grow. Alongside most cells there is either a basement membrane or a collagenous network made by fibroblasts that will guide the cells' growth. Since ischaemia and most toxins do not destroy collagen, it will continue to exist even when the cells around it are dead.

Healing - Example of regeneration

Acute tubular necrosis (ATN) in the kidney is a case in which cells heal completely by regeneration. ATN occurs when the epithelial cells that line the kidney are destroyed by either a lack of oxygen (such as in hypovolemic shock, when blood supply to the kidneys is dramatically reduced), or by toxins (such as some antibiotics, heavy metals or carbon tetrachloride).

Although many of these epithelial cells are dead, there is typically patchy necrosis, meaning that there are patches of epithelial cells still alive. In addition, the collagen framework of the tubules remains completely intact.

The existing epithelial cells can replicate, and, using the basement membrane as a guide, eventually bring the kidney back to normal. After regeneration is complete, the damage is undetectable, even microscopically.

Adapted from the Wikipedia article "Healing by regeneration", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki