Femke Mathot

6 Vascularization in stem cell seeded nerve allografts 101 Revascularization pattern The vessels of normal, non-operated nerves aligned in the same longitudinal direction as the axons and the vasculature is equally distributed among the entire length of the nerve. The preserved vessels in autograft nerves seemed to be largely longitudinally aligned consistent with inosculation pattern of revascularization, but were less extensively present than in normal nerves. Unseeded allografts had less vascularization in general and demonstrated minimal if any vascularization in their mid-segment. In both MSC-seeded allograft groups, an extensive, non-aligned network of micro-vessels extended from the very proximal to the very distal graft end with a centripetal pattern of revascularization. In all groups, the ingrowth of vessels occurs from both nerve ends, but particularly from the proximal stump. Vascular volume The vascular volume measurements showed the same trend as the vascular surface area measurements; the allografts seeded with differentiated MSCs contained the highest vascular volume (4.6 ± 3.6%), the outcomes of the autografts (3.78 ± 0.7%) and the allografts seeded with undifferentiated MSC (3.4 ± 0.2%) did not differ and the unseeded allografts scored the least (2.7 ± 1.0%). ANOVA analysis between groups showed no statistically significant differences between the groups (F=0.916; p=0.455) ( figure 4 and 5 ). The vascular surface area and the vascular volume measurements were significantly correlated (r=0.416; p=0.008). Figure 4. The vascular volume outcomes of autografts, allografts, allografts seeded with undifferentiated MSC and allografts seeded with differentiated MSCs. None of the differences between the groups was statistically significant. Error bars = standard deviation of the mean uMSC = undifferentiated Mesenchymal Stem Cells, dMSCs = differentiated Mesenchymal Stem Cells Autografts Allografts Allografts + uMSCs Allografts + dMSCs Normal nerves 0 2 4 6 8 10 Vascular volume Mean vessel %