In this research line the (patho)fysiologie of cartilage disease is studied using state of the art molecular biological research tools such as microarray analysis, chip on chip, chip on DNA and DNA methylation arrays combined with biophysical techniques like Förster (Fluorescence) Resonance Energy Transfer (FRET), Fluorescent Recovery after photobleaching (FRAP), single particle tracking and Fluorescent Correlation Spectroscopy (FCS). The aim is to unravel the intricate intracellular network of protein-protein and protein-DNA interactions that are responsible for homeostasis of healthy articular cartilage. The data are feed into computer models that are aimed at reconstructing an in silico chondrocyte. These models allow visualization of key events in chondrocyte biology and will enable the simulation of chondrocyte behavior in health and disease. This research strategy will be used to identify new targets for therapeutic intervention in cartilage disease and cartilage regeneration and predict their potential (side-)effects. These new targets can be used for optimization and incorporation of biofunctionality in scaffolds for cartilage repair.
Here research activities are aimed at optimization of the protocols for culture expansion of primary chondrocytes and mesenchymal stem cells (MSC) aimed at improved and accelerated de novo cartilage matrix formation upon implantation in patients. Attention is focused on the role of the MSC in cartilage repair. We have shown that MSCs stimulate cartilage formation of chondrocytes by stimulating chondrocyte proliferation and matrix production rather than differentiating themselves into chondrocytes. Furthermore, we have shown beneficial effects of micro-aggregation of chondrocytes on cartilage matrix formation. Activities are focused on unraveling the underlying molecular mechanisms and use these mechanisms for optimization of current cell therapy protocols. We plan to develop intraoperative methods for the generation of micro-aggregates of chondrocytes and MSCs that can be implanted in cartilage defects in an one step surgical procedure. In addition, the molecular mechanisms underlying the improved cartilage formation in hypoxic conditions is studied with special attention for the enzyme AMPKinase as a key mediator of cell metabolism. Using state of the art molecular biological techniques and mass spectrometry, we aim at elucidating the key molecular mechanisms involved in improved cartilage formation in these models and translate these mechanisms in strategies for cartilage repair.
Research activities are aimed at developing a scaffold for extrahepatic transplantation of islets of Langerhans to bypass the inadequate current transplantation in the liver. Research focuses on the development of sheets with microwell designs for capturing individual islets. Strategies are developed to enable the rapid vascularization of these scaffolds for example by biofunctionalization of the biomaterial surface using growth factors. Various technologies are used to incorporate holes in the scaffold that are compatible with blood vessel ingrowth. These scaffolds are implanted in relevant small animal models to study biocompatibility and Islet survival and function with respect of glucose homeostasis.
In this research line we aim at the development of biomimetic injectable in situ gelating hdyrogels for soft tissue repair focusing on cartilage and Islets of Langerhans.
In cartilage, present attention is focused on the exploitation of enzymatic cross linkable hydrogels using chemically modified natural and synthetic polymers. Examples of such natural polymers are glycosaminoglycans and / or collagens. Attention is focused both on the fundamental aspects of polymer chemistry and development of chemical methods needed for hydrogel generation as well as on methods for the detailed physicochemical characterization of the hydrogels at macro- and nanoscale. The developed hydrogels will be evaluated in vitro and in vivo using suitable animal models; i.e. mice for initial biocompatibility studies and rabbits and horses for orthotopic implantation.
In Islets of Langerhans research, the injectable hydrogels will be developed to facilitate neovascularization and survival of the transplanted islets. Using a combinatorial chemistry approach in combination with microfluidics gel compositions will be optimized for specific purposes; i.e. Islet survival after transplantation by facilitating neovascularization; Islet reconstruction out of single dispersed β and α cells or of the stem cells of the Islets (duct cells). These structures are evaluated in relevant animal models.
In the future, using the combinatorial chemistry approach injectable in situ gelating matrices will be developed optimized for specific regenerative purposes. Collaborative projects have been started to develop a specific matrix for skin wound healing that can be applied in a spray or to develop an injectable matrix for adipose tissue reconstruction in plastic surgery. These novel hydrogels are evaluated in relevant animal models.