Limitation Of The Strengths And Repitations Of Human...

Many animals have the ability to restore their tissue after injury. Among the most fascinating vertebrate models are newts and axololts, which can regenerate their entire appendages. This intricately regulated process is mediated by the formation of the blastema. While much has been learned about limb regeneration in the past decades, several underlying mechanisms remain to be elucidated. A recent study by Sandoval-Guzman and colleagues has shed light on the regeneration of muscle in such salamander species. This review will briefly discuss the findings of the paper and compare the strengths and limitations of each research model. To study the regenerative capacity in the newt and axolotl after amputation, the authors employed a†¦show more content†¦Next, the authors sought to determine whether myofiber dedifferentiation was taking place during the early stages of regeneration. This was true in the newt species, as evidenced by the existence of YFP MHC positive cells in the stump region and the lack of such nuclei in the blastema. Furthermore, cells within the distal blastema were mononuclear and actively proliferating as determined by the PCNA and EdU assays. This finding prompted researchers to examine if myofiber dedifferentiation was paralleled in the axolotl. Surprisingly, YFP positive nuclei were restricted to the upper limb proximal to the amputation site, and absent in the lower limb and hand. This indicated that myofibers did not invade the blastema or contribute to limb regeneration. Moreover, such outcome was verified using a grafting experiment that transferred donor blastema â€Å"CAGGS: ert2-cre-ert2-T2A-nucGFP† to the upper arm tissue of the amputee host â€Å"CAGGS:loxp-GFP-STOP-loxp-Cherry†. The fusion of transgenic myoblast nuclei gave rise to a chimeric limb that expressed Cherry in its myofibers after treatment with tamoxifen. Subsequently, the newly formed limb was amputated and Cherry positive cells failed to colonize the regenerate tissue. With myofiber dedifferentiation ruled out, Sandoval-Guzman and colleagues went on to investigate other mechanisms that can stimulate de novo myogenesis in the axolotl. The authors