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Regenerative Medicine for Battlefield Injuries

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Annual rept. 19 Oct 2011-18 Oct 2012

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The purpose of this research is to identify the optimum combination of growth factors that stimulate cartilage regeneraton across a critical size defect CSD in a long bone, using the axolotl, Abystoma mexicanum as a model system. The scope of the research is to characterize fracture repair and determine the length of the CSD in the fibula, use bioinformatics analysis and biochemical analysis of limb proteins to reveal the potential growth factors involved in CSD regeneration, and test these growth factors for their ability to stimulate cartilage regeneration when delivered by a standard pig small intestinal submucosa scaffold SIS. In year one, we have characterized the response of the fibula to fracture and segment defects of 10, 20, 40 and 50 via X-ray, CT, methylene bluealizarin red MBAR limn skeleton whole mount staining, and H E staining of sections at intervals of 15 days, one month, six weeks, two months and three months post-operation. Cartilage formation is detected by H E staining within one month after fracture and by six weeks with MB stain. The cartilage is mature by 3 months and can be visualized by X-ray and CT. Using the same imaging methods, we determined that the CSD length at which 50 or more of cases fail to regenerate is slightly less than 40 of the length of the bone. Because 50 defects fail to regenerate by 3 months in 100 of cases, we will use these defects to test growth factors. We found that a gelatin-coated 8-strand SIS braid releases protein continually for at least 72 hr., indicating that the choice of this scaffold was the right one. Experiments grafting axolotl cartilage and muscle to Xenopus tarsal CSDs indicate that the tissues enhance regeneration, most probably by a paracrine effect they also enhance regeneration of amputated Xenopus limbs, providing evidence that limb proteins are capable of stimulating regeneration across gaps.

Subject Categories:

  • Biochemistry
  • Anatomy and Physiology
  • Medicine and Medical Research

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