Biomaterials with Functionally Graded Stiffness

There are many different tissues in the body, each possessing different mechanical properties and varying amounts of stiffness that are needed for cells to function properly and survive. A challenge to recreating in vitro tissues is to accurately recapitulate the mechanical properties of the native tissue. The focus of this research was to produce a substrate with a functionally graded stiffness for use with in vitro culture of cardiomyocytes, the cells of the heart responsible for contraction. Young's modulus, a measure of stiffness of materials, is a key characteristic parameter for tissues. Currently, there is a lack of substrate systems that span the range of Young's modulus needed to represent both healthy and diseased myocardium. This is problematic when trying to model cardiovascular disease. For example, after myocardial infarction, there are regions of soft and stiff underlying tissue that impact the behavior of cardiomyocytes differently. The goal of this research was to create a substrate system with a stiffness gradient spanning from 5 to 50 kPa upon which the cardiomyocytes derived from stem cell could be cultured. This in vitro substrate system was designed to mimic the range of physiological environments in which cardiomyocytes exist in vivo . This substrate model is specifically being designed to aid in better understanding and reducing cardiovascular disease. The method investigated that showed the most promise was UV curing of polyacrylamide hydrogels. A gradient photomask was designed to allow different amounts of UV light to penetrate over the span of the substrate. This mask was then placed over the prepolymer gel during UV exposure. This method produced a stiffness gradient of 55 to 75 kPa over a 1 cm distance. Further work is needed to optimize the photomasks and gel reagents to produce the lower end of modulus representative of healthy myocardium. Support or Funding Information Supported with funding from the Karen Thompson Medhi Professor at the University of Wisconsin‐Madison and the National Science Foundation through the University of Wisconsin‐Madison Materials Research Science and Engineering Center (DMR‐0520527) and Nanoscale Science and Engineering Center (DMR‐0425880). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Science Foundation. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .