Joris van Dongen

321 Adipose ECM hydrogels to release paracrine factors DISCUSSION The results of this research show that human adipose tissue-derived ECM hydrogel are non-cytotoxic and support adhesion, survival as well as migration and proliferation of immortalized ASCs. These are promising results that warrant further implementation e.g. as a delivery vehicle of stem cells, in animal and later also clinical trials. Cells cultured in the 3D hydrogel environment showed different morphologywith respect to extending and elongating structures compared to cell morphology in plain cell culture plastic 2D environment culture.We also showed that immortalized ASC show the same characteristics as normal ASC (CD markers, colony forming ability and differentiation ability). ECM derived hydrogels can have various implementations.. ECM hydrogels are currently being used as a 3D culturing model and as bioengineering printing bio- ink. As shown by this study, culturing of cells differs in a 2D environment as compared to a 3D environment, especially in morphology. A study by Sung et al. showed that fibroblast in 3D culture released more signalling molecules which resembles more precisely their behaviour in the human organism. 29 Therefore, a 3D ECM hydrogel culture system is a better representative of how processes in the human body function and, therefore, an ideal culture system to study the effect of treatments on different cellular processes. The ECM hydrogels will likely impact bioengineering, as bio-ink for printing organoids together with vascular and connective tissue cells. Currently, ECM hydrogels from different origins have been tested in a variety of medical fields. 18-22 A study by Ghuman et al. induced a stroke in rats and subsequently injected an ECM hydrogel derived from adult porcine urinary bladder tissue into the necrotic stroke area. 30 This resulted in increased tissue regeneration in the brain after injection of an ECM hydrogel. The injected ECM hydrogel caused more cell infiltration as compared to the control group. Although different origins of extracellular matrix are available, the use of human adipose tissue-derived ECM provides several advantages as compared to decellularized tissue from other origins. First, human adipose tissue is more easily accessiblewithout adverse side-effects compared tootherorgansof thehumanbodysuch as skin. Second, the human adipose tissue is widely available since patients frequently donate liposuction adipose tissue. Third, the obtained adipose tissue-derived ECM can be used as both autologous as well as allogeneic treatment modality, while autologous transplantation is not possible for most of the other decellularized organs of the human body ( e.g. heart, lung). Allogeneic transplantation is possible due to the lack of a cellular component causing an immune response after transplantation. This study served to setup a platform technology and focused on potential adverse influence of ECM hydrogels on two stromal cell types ASC and fibroblasts. Current research comprises of co-culture systems in ECM hydrogels of different organs and investigating processes relevant to tissue regeneration such as vascularisation. Thus, co-cultures of two or more