Femke Mathot

Chapter 6 94 ABSTRACT Purpose Adipose derived mesenchymal stem cells (MSCs) are hypothesized to supplement tissues with growth factors essential for regeneration and neovascularization. The purpose of this study was to determine the effect of MSCs with respect to neoangiogenesis when seeded onto a decellularized nerve allograft in a rat sciatic defect model. Methods Allograft nerves were harvested from Sprague-Dawley rats and decellularized. MSCs were obtained from Lewis rats. 10mm sciatic nerve defects in Lewis rats were reconstructed with reversed autograft nerves, decellularized allografts, decellularized allografts seeded with undifferentiated MSC or decellularized allografts seeded with differentiated MSCs. At 16 weeks, the vascular surface area and volume were evaluated. Results The vascular surface area in normal nerves (34.9 ± 5.7%.), autografts (29.5 ± 8.7%), allografts seeded with differentiated (38.9 ± 7.0%) and undifferentiated MSCs (29.2 ± 3.4%) did not significantly differ from each other. Unseeded allografts (21.2 ± 6.2%) had a significantly lower vascular surface area percentage than normal non-operated nerves (13.7%, p=0.001) and allografts seeded with differentiated MSCs (17.8%, p=0.001). Although the vascular surface area was significantly correlated to the vascular volume (r=0.416; p=0.008), no significant differences were found between groups concerning vascular volumes. The vascularization pattern in allografts seeded with MSCs consisted of an extensive non-aligned network of micro-vessels with a centripetal pattern, while the vessels in autografts and normal nerves were more longitudinally aligned with longitudinal inosculation patterns. Conclusions Neoangiogenesis of decellularized allograft nerve was enhanced by stem cell seeding, in particular by differentiated MSCs. The pattern of vascularization was different between processed allograft nerves seeded with MSCs compared to autograft nerves.