Joris van Dongen

349 English summary The key therapeutic components of tSVF consist of a cellular fraction i.e. ASCs and tissue fraction i.e. extracellular matrix. ASCs are one of the regenerative key players in the cellular fraction of tSVF and are able to stimulate other cell types by released paracrine factors. In chapter 12 , extracellular matrix was isolated through an extensive decellularization protocol and enzymatically micronized using pepsin to subsequently form a self-assembly hydrogel. This hydrogel was loaded with conditioned medium from cultivated ASCs containing the complete secretome of ASCs in order to stimulate angiogenesis aswell as fibroblast proliferation andmigration in vitro .This study showed that extracellular matrix isolated from tSVF plays an important role in binding and releasing growth factors released from ASCs in a controlled fashion. Moreover, these factors are still biologicallyactiveovertime e.g. stimulateangiogenesis aswell asfibroblast proliferation and migration. No differences were observed between extracellular matrix isolated from diabetic patients and non-diabetic patients. Besides in chapter 5, we have showed the anti-inflammatory effect of tSVF on pro-inflammatory chondrocytes in vitro . These findings indicate that tSVF is able to stimulate angiogenesis, remodel extracellular matrix and acts immunomodulative in vitro . The extracellular matrix derived hydrogel loaded with released factors from ASCs might be a therapeutic option itself in the future as well. This hydrogel is suitable for allogenic transplantation and contains all regenerative key components of tSVF. Yet, the production of the extracellular matrix derived hydrogel consist of an extensive decellularization process requiring cytotoxic reagents. Hence, in chapter 13 we have studied the cytotoxic effects of these hydrogels on connective tissue i.e. fibroblasts. Cytotoxicity was studied using a metabolic activity assay (MTT) and show that the extracellular matrix derived hydrogels were non-cytotoxic. Therefore, clinical use of these hydrogels might be an interesting possibility in the future.