Joris van Dongen

297 Adipose ECM hydrogels to release paracrine factors the hydrogels did not substantially affect the biological activity nor concentrations of the released factors; small differences in kinetics of biological assays were seen for unknown reasons. Yet, diabetic ECM derived hydrogels had a too low mechanical strength and are therefore less suitable for clinical applications. Thus, CMe incubated non-diabetic derived hydrogels seems to be a promising new treatment modality to augment wound healing. The released factors byASC-CMe-loaded ECMhydrogels stimulated several important wound healing related processes including an increased fibroblast proliferation and migration as well as sprouting by HUVECs i.e. surrogate angiogenesis. Diabetic origin did not affect either of these processes, except that cell proliferation of fibroblasts was reduced 24h and 48h after release of factors by non-diabetic hydrogels in comparison with diabetic hydrogels. Yet, the immunoassay showed similar concentrations of factors released by both types of hydrogels. This suggests that the releasing pattern of some factors might be different when released by hydrogels of diabetic origin e.g. a faster release. A faster release of factors results, however, in a faster depletion of factors in ASC-CMe-loaded hydrogels and thus a shorter time to promote wound healing. Moreover, factors will be actively subtracted from the hydrogel in vivo instead of accumulation of factors until a concentration balance is reached between inside and outside the hydrogel. Additionally, fibroblast cell proliferation increased over time after using released factors in an incremental fashion up to 96h. Wound healing comprises different processes that show spatiotemporal overlapping phases with different processes of which some e.g. angiogenesis, fibroblast proliferation and migration are investigated in this study. Our results suggest that released factors fromASC-CMe loaded hydrogels influence both the course and kinetics of these phases. These human ECM-derived hydrogels allow the allogenic administration because both factors released by ASC as well as ECM will not induce an adverse immune reaction. In fact, ECM components are evolutionary highly conserved which warrants the use of animal-derived ECM hydrogels e.g. pig dermal ECM hydrogels. The potential therapeutic value of this ‘one-donor-for-all’ treatment modality for wound healing purposes is based on biological properties as well as physical properties. Biologically, a plethora of factors can be bound and released by ECM. In this way, wound healing can be enhanced by influencing processes like angiogenesis, apoptosis, chemoattraction of immune cells and support of local mesenchymal or progenitor cells 29 . Angiogenesis is enhanced by VEGF and FGF1, especially under hypoxia 30 . ASC-CMe, which contains VEGFandFGF1, increases endothelial proliferationand suppresses cell apoptosis under hypoxia. Both proliferation of endothelial cells and survival are important mechanisms in wound healing 31 . Additionally, VEGF also functions as a chemoattractant for local progenitor cells as well as macrophages 32 . Macrophages, attracted by chemokines