Peripheral Nerve Contribute to Repair And Regen-eration of Injured Mammalian Tissue

Background: Mammals have lost multi-tissue regenerative capacity in comparison with amphibians, but they have this ability for the distal digit amputation. During regeneration of the mouse digit tip, Schwann Cell Precursors (SCPs) that exist in peripheral nerve, dedifferentiate and move into the injured tissue. Schwann cell precursors are derived from neural crest, researches indicate that neural crest-derived cells appear to respond to injury and stress by acquisition of a new cell fate in a process that likely involves dedifferentiation and in vivo reprogramming. Recent researches also showed mesenchymal cells that reside within nerves play a crucial role in mammalian tissue repair and regeneration. They identified a specific popu-lation of mesenchymal cells that represent a reservoir of precur-sors that expand and differentiate into bone and dermis during tissue regeneration and repair.Materials and Methods: Immunostaining used for visualizing to report expressing PDGFRα gene. For neural crest-derived, using a mouse carrying a Wnt1-Cre transgene that is expressed in embryonic neural crest precursors and a TdTomato reporter gene with an upstream floxed stop cassette in the Rosa26 locus. Results: It has been shown, Following digit tip removal, these dedifferentiated SCPs localize to injured tissue, where they se-cret oncostatin M (OSM) and platelet-derived growth factor AA(PDGF-AA), to promote self-renewal of mesenchymal cell, expansion of the blastema, and regeneration. Previous research showed that OSM also can promote osteogenic differentiation. The authors discovered that kinds of epineurial and perineurial fibroblasts exist regardless of whether the nerve is damaged or not. However, endoneurial fibroblasts change and downregulate some connective-tissue-associated genes while upregulating other genes, it highlights the hypothesis in which regenerative and repair cells are derived from endoneurium. endoneurial fi-broblasts arise from neuroectoderm neural crest cells instead of the lateral plate mesoderm.Conclusion: Finally, proposed that nerve damage causes dedi-fferentiation of Schwann cells and expansion of endoneurial precursor-like mesenchymal cells which then migrate into in-jured tissues, where they promote repair by two complementary mechanisms; the dedifferentiated Schwann cells secrete growth factors like PDGF-AA and oncostatin M and nerve-derived mesenchymal cells differentiate into tissues like the dermis and bone in response to local cues.

کلیدواژه ها:

Mammalian Tissue Repair ، Mesenchymal Cell ، Pe-ripheral Nerve ، Schwann Cell Precursors