1. By Jordan Sudario-Cook

2. Axolotl The axolotl is a species of salamander that lives mainly in areas of Mexico. This species of salamander have extensive regenerative properties and can regenerate their limbs, tail, spinal cord and even parts of their brain. Researchers have been studying this animal for many decades trying to figure out the process in which these animals regenerate their limbs and how they could eventually replicate the process in humans.

3. Current Research Right now scientists have been using two main procedures to study the regenerative properties of Axolotl limbs. In the primary method the scientists simply amputate a leg from the Axolotl. In the second method, scientist create a wound in an area of the body and cut a nerve around the wound and place a skin graft from an area of the limb onto the wound.

4. Regenerative Process After the limb has been amputated, neurotrophic factors called fibroblast growth factors act on the wound epithelium of the area forming an apical epithelial cap which is a layer of signaling cells. This apical epithelial cap, along with the cut nerve, help to inhibit wound healing. While this cap is forming, fibroblasts from the surrounding connective tissue migrate to the amputated area.

5. Regenerative Process(cont.) These fibroblasts form a blastema which is a mass of cells located at the amputated site that are capable of regeneration. At first these blastema were thought to contain undifferentiated pluripotent cells but it is now believed that these blastema may contain cells that remember the cells of the former limb. This means that these cells are a collection of restricted progenitor cells. Once the limb bud forms, research has shown that the same developmental genes (such as HoxA and HoxD) that were seen in the developing limb in the embryo are also present in this limb regeneration. Once these genes are presented, the limb reforms in the span of about a month to two months and is indistinguishable from the former limb.

6. Human Regeneration By fully understanding this process in the Axolotl salamander, scientists may be able to replicate the process in humans. This process is still not fully understood and could still take many years to truly see how it works. The major landmark would be figuring out how to prevent the natural scarring that occurs in humans as the blastema formation seems to be the major factor in regenerating limbs.

7. Ethical Considerations The issue of animal testing is a major consideration because these animals are being bred only to be experimented on. The Axolotl species is close to extinction. Giving humans the ability of other animals is seen by some people as going against the process of evolution.

8. Future If scientists were able to replicate this in humans, this method could be used in amputee patients and maybe even in organ regeneration. This field could completely replace prosthetics.

9. References http://life-sea.blogspot.com/2011/12/axolotl.html http://en.dogeno.us/2009/08/cells-memorize-their-tissue-origin-during-axolotl-limb-regeneration- the-blastema-is-a-heterogeneous-collection-of-restricted-progenitor-cells/ http://en.dogeno.us/2009/08/cells-memorize-their-tissue-origin-during-axolotl-limb-regeneration- the-blastema-is-a-heterogeneous-collection-of-restricted-progenitor-cells/ http://onlinelibrary.wiley.com/doi/10.1002/ar.22529/pdf downloads.hindawi.com/journals/tswj/2006/630306.pdf http://en.wikipedia.org/wiki/Axolotl http://www.sci-news.com/genetics/article00615.html http://www.rationalskepticism.org/biology/fluorescent-cells-tracked-in-axolotl-limb-regeneration- t22918.html http://www.rationalskepticism.org/biology/fluorescent-cells-tracked-in-axolotl-limb-regeneration- t22918.html http://www.wired.com/wiredscience/2009/07/regeneration/ http://www.biomedcentral.com/1741-7007/7/83