Tiam Mana Saffari

205 FUNCTIONAL MOTOR RECOVERY OF STEM CELLS DELIVERED TO NERVE GRAFTS 9 fibers do not neccesarily feature improved contractility 36 . ITF has been described to objectively quantify contractility of muscle fibers and is easily reproducible 36 . The vulnerability of CMAP measurements, which is affected by the placement of all individual electrodes, may explain why the CMAP outcomes are greater than the ITF measures 40 . Histologically, the autografts had significantly better N-ratios in the peroneal nerves at both time points compared to all other groups. Although not examined, this could be explained by less formation of fibrosis in autografts 41 . Due to small groups and insufficient sensitivity of density measures, the histology outcomes could not be significantly confirmed by immunof luorescence outcomes, but unseeded nerve allografts subjectively seem to contain less Schwann cells and axons compared to all other groups. Autografts were used as control group to test whether MSCs could improve outcomes of decellularized allografts up to a level equal to that of autografts. While an additional control group in which sham surgery is performed would also be interesting to include, it would require the undesirable and precious use of additional animals. Alternatively, outcomes of the operated side were normalized to the unoperated control side in order to relate the test-outcomes to normal nerve and muscle function (providing a R/L ratio). The significant differences between groups presented at 12weeks and normalized after 16 weeks, insinuates that nerve regeneration in motor nerves in rats will occur after 12 weeks, independently from the type of nerve repair. This finding may be correlated to the demonstrated finite survival of MSCs up to 29 days in vivo . It is suggested that MSCs significantly enhance nerve regeneration up to 12 weeks after which the superlative neuroregenerative capacity of rats takes over, due to the apoptosis of the MSCs 42 . The superlative neuroregenerative capacity of rats is a commonly described explanation and can be mitigated in a larger animal model 26,39 . Absent significant differences when comparing cross-sectional tibial muscle areas is also a likely consequence of using a small animal model with small cross-sectional nerve areas, relatively leading to larger standard errors and less significant differences between groups 31,32 . Future research should be performed on multiple time points in larger animal models with larger nerve gaps to potentially translate outcomes to humans.