Fabrication of microchannels in methacrylated hyaluronic acid hydrogels

Culturing cells in a vascularized three-dimensional (3D) hydrogel scaffold has significant applications ranging from tissue engineering to drug discovery. In many large 3D scaffolds, mass transport and nutrient exchange leads to cell necrosis, limiting functionality. Here we present a technique for fabricating microfluidic channels in cell-laden methacrylated hyaluronic acid (MeHA) hydrogels. Using standard soft lithographic techniques, MeHA pre-polymer was molded against a PDMS master and cross-linked using UV light. A second UV cross-linking step generated sealed channels. Channels of different dimensions and geometric complexity demonstrated that MeHA, though highly porous, is a suitable material for microfluidics. Cells embedded within the microfluidic molds were well distributed and media pumped through the channels allowed the exchange of nutrients and waste products. Through repeated stacking and crosslinking steps, we were able to form multiple layers of 3D MeHA channels to form a highly perfuse microchannel network. Incorporating collagen into the MeHA to form a semi-interpenetrating network enabled endothelial cell attachment to the interior of the channels. Further development of this technique may lead to the generation of biomimetic synthetic vasculature for tissue engineering and drug screening.