Long-term survival of implanted cells requires oxygen and nutrients, the need for which is met by vasculari- zation of the implant. The use of scaffolds with surface-attached heparin as anchoring points for angiogenic growth factors has been reported to improve this process. We examined the potential role of surface modification of gelatin scaffolds in promoting endothelial cell infiltration by using a unique macromolecular conjugate of heparin as a coating. Compared to other heparin coatings, this surface modification provides flexible heparin chains, representing a new concept in heparin conjugation. In vitro cell infiltration of scaffolds was assessed using a three-dimensional model in which the novel heparin surface, without growth factors, showed a 2.5-fold increase in the number of infiltrating endothelial cells when compared to control scaffolds. No additional improvement was achieved by adding growth factors (vascular endothelial growth factor and/or fibroblast growth factor-2) to the scaffold. In vivo experiments confirmed these results and also showed that the addition of angiogenic growth factors did not significantly increase the endothelial cell infiltration but increased the number of inflammatory cells in the implanted scaffolds. The endothelial cell-stimulating ability of the heparin surface alone, combined with its growth factor-binding capacity, renders it an interesting candidate surface treatment to create a prevascularized site prepared for implantation of cells and tissues, in particular those sensitive to inflammation but in need of supportive revascularization, such as pancreatic islets of Langerhans. / <p>De två sista författarna delar sistaförfattarskapet.</p>

In search of better scaffolding materials for in vitro culture of chondrocytes, the combination of chitosan (similar to glycosoaminoglycans) and gelatin (denatured collagen) was tested due to its resemblance to cartilage extra-cellular matrix (ECM). Porous scaffolds were fabricated from chitosan gelatin blends (1:1, 2:1, and 3:1). The response of chondrocytes to them was evaluated from the amount of sulphated GAG and collagen type 2 secreted after 3 and 5 weeks. The effect due to static (transwell inserts) and dynamic (rotating bioreactor) culture methods was analyzed. Results indicate that 1:1 chitosan gelatin blends showed the best chondro-conductive potential. The rotating bioreactor facilitated better cell distribution across scaffold but did not show higher ECM secretion compared to transwell culture after 3 weeks. Gelatin leeched out by dissolution in culture media and left an open and interconnected chitosan network. Chitosan gelatin scaffolds show a potential for use in cartilage tissue engineering applications