Tiam Mana Saffari

255 SUMMARY / SAMENVATTING 12 studies in this thesis. We recommend this simple technique to add vascularization to various tissues in the lower abdomen, genital area, thigh, and upper limb of the rat. To objectively measure angiogenesis in nerve samples, the use of conventional photography and micro computed tomography (micro CT) was investigated in Chapter 4 . Vascular volume and vascular surface area, calculated with micro CT and photography respectively, both reflect vessel percentage of the nerve graft and could be used in the same samples. Besides the amount of vascularity, these methods allow for dimensional visualization of vessels to allow for insight in the connectivity of the vascular tree. The micro CT specifically, provides three-dimensional (3D) interconnectivity of the vasculature and contributes to crucial description of neovascularization patterns. Our results indicated a significant correlation (r = 0.951, p = 0.049) between the vascular volume and the vascular surface area measurements, demonstrating that these methods could be used either complementary or separately, depending on the aims of the study. In Chapter 5 , described techniques in Chapter 3 and Chapter 4 were combined to investigate revascularization patterns in a rat sciatic nerve defect model over time. Starting at two weeks, vascularization consisting of a mesh network occurred from both host stumps in decellularized nerve allografts and SIEF nerve samples, leaving the middle part avascularized. Over time, sprouted vessels reached the middle parts of the nerve and this was more evident from the proximal than from the distal end. The SIEF flap significantly improved revascularization of allograft nerve at two, 12 and 16 weeks compared to allograft alone. In nerve autografts, longitudinal running vessels were recognized that ran along the entire length of the nerve. These vessels appeared thicker compared to the newly formed vessels in the allograft and SIEF nerve samples, comparable to unoperated samples (negative control). This study suggests that an improved vascularized bed promotes longitudinal inosculation, in particular proximal inosculation, and confirms the theory of centripetal revascularization. In Chapter 6 , the effect of angiogenesis was studied at a cellular level in a rat sciatic nerve defect model to investigate its effect on nerve fibrosis. In this study, we demonstrated that a well vascularized bed (i.e. SIEF f lap) enhances the local cellular environment near the nerve repair site, called the paracrine environment, to support tissue healing after injury and subsequently diminish fibrosis. Fibrocytes