Development of a gelatin-based hydrogel to deliver pro-angiogenic growth factors for creating human blood-brain blood

The brain is, by far, the most complex and delicate human organ, which has evolved with an extra protective system of blood-brain barrier (BBB) that prevents toxins and other harmful substances from reaching it. Due to this particularity, pharmacological companies face the challenge of translating laboratorial results to clinical, deterring from investing in an active BBB drug-targeting program. Thus, relevant in vitro human BBB models are needed to better underline the pathophysiological molecular transport mechanisms and improve the design of targeted therapies for neurological disorders. With the goal to develop a BBB in vitro model with properties closest to the ones found in human brain, a mimicking extracellular matrix (ECM) was developed as gelatin-based hydrogel incorporating heparin, as a pro-angiogenic growth factor immobilization molecule, and hyaluronic acid (HA), to improve mechanical strength and regulation of physiological processes related with BBB cells. The hydrogel 3D-network was achieved by activation of carboxylic acid groups of heparin and HA with EDC/sulfo-NHS that served as crosslinking agent to the amino groups of gelatin by click chemistry. Physicochemical and rheological properties of hydrogels were investigated, along with cellular studies using endothelial cells (HUVECs), namely membrane adhesion and cell-cell cohesion.