Femke Mathot

Chapter 6 102 Figure 5. Snapshots of the obtained micro-CT scans that served for the volume measurements of normal nerves (A) autografts (B), allografts (C), allografts seeded with undifferentiated MSCs (D) and allografts seeded with differentiated MSCs (E). The nerves are positioned from proximal (left) to distal (right). The smallest vessels are not detected by the micro-CT due to its effective pixel size. DISCUSSION The purpose of this study was to determine whether the previously demonstrated different gene expression profiles of differentiated and undifferentiated MSCs would lead to different levels and patterns of vascularization when dynamically seeded onto processed/ decellularized nerve allografts. Digital photography and micro-CT imaging allowed for the quantification and comparison of vascularity. Neoangiogenesis has been previously quantified by counting of RECA-1 positive structures (immunohistochemical staining) and histomorphometric evaluation or the measurement of capillary density. 20, 43-45 These methods unfortunately fall short when aiming to precisely quantify and describe vascularity volumes and vascularization patterns. An evaluation strategy in which both 2D and 3D measures can be reliably obtained was used in the current study in order to compare the effect of undifferentiated versus differentiated MSCs. 42 With respect to vascularization, there was an increase in the vascular surface area of processed allografts when seeded with undifferentiated and differentiated MSCs. However, only the effect of differentiated MSCs was statistically significant, suggesting that differentiated MSCs enhance (neo)angiogenesis to a greater extent than undifferentiated MSC. The enhanced expression of neurotrophic and angiogenic genes of MSCs when