A 3-dimensional vascularized cardiac tri-culture model using chitosan nanofiber scaffolds

The development of an in vitro tissue model that can mimic the 3-dimenisonal (3-D) cellular architecture and mosaic of myocardial tissue holds great value for cardiac tissue engineering, modeling, and cardiovascular drug screening applications. The main objective of this project was to develop a 3-D vascularized cardiac tissue model in vitro for improved survival and function. The cellular mosaic of the myocardial tissue demands the intricate integration of an extracellular matrix-like scaffold, cellular constituents, and biological factors. The first aim of the research was to fabricate and characterize a biodegradable chitosan nanofiber scaffold that would resemble the extracellular matrix (ECM) physically and chemically. Chitosan, a natural polysaccharide that shares structural homology to the ECM glycosaminoglycans was processed into nanofibers via electrospinning to resemble the physical nano-architecture of the ECM. The second aim was to biologically modify the scaffold using a two step method: (1) Adsorption of fibronectin to improve cellular attachment and migration and (2) Induction of endothelial tubulogenesis to recreate the vascularized architecture of the myocardium. The third aim was to investigate the effect of co-culturing cardiomyocytes with fibroblasts on cardiomyocytes’ survival and contractility in the vascularized 3-D chitosan scaffold. This was based on the fact that 70% of the native myocardial tissue is composed of fibroblasts The chitosan scaffold was characterized for its physio-chemical properties, including in-vitro structural integrity and bio-degradability. The biomodification of the scaffold via fibronectin adsorption improved cellular attachment, verified by staining of actin (cytoskeletal protein) and vinculin (cell-adhesion protein). The endothelial cells formed a network of interconnected tubes and secreted GAGs that were immobilized onto the chitosan scaffold. The cellular studies showed that cardiomyocyte mono-cultures resulted in islands of isolated contractions and minimal ...