P-12

To avoid animal testing, in-vitro cell-based assays are used for pharmaceutical testing. These concepts advantageously circumvent species differences in terms of genetics and biochemistry by employing cells of human origin. We work on a heart-on-a-chip (HoaC), a microfluidic device providing an excellent model for the human heart. A biocompatible and flexible cell substrate is essential in order to maintain the physiological function of cardiomyocytes. An indicator is necessary to determine the cell culture condition. Current methods to study viability are able to detect when effects are severe, meaning cells are already dying. We will test a promising new method using atomic force microscopy (AFM) in fluid combined with the nAnostic® tool as a biomarker for proper cell function (to indicate compromised cell function at an initial stage). The AFM gathers information by "feeling" the surface with a mechanical probe and is able to recognize details of down to one nanometer on the cell. Membrane protrusions or indentations are quantified using computer vision according to nAnostic® algorithms. As a candidate structure, tiny membrane invaginations of 50-200nm in diameter are quantitated. It is hypothesized, that the number of these „caveolae“ will correlate with the caveolin-3 protein expression and with the degree of differentiation of HiPSC-cardiomyocytes. The technique is employed to investigate these nanoscopic membrane features influenced by polymer substrates desired for HoaC devices. Surface density and architecture of caveolae are evaluated as an indicator for affected heart cell function.

Schematic illustration of heart cell tissue embedded in a microfluidic chip. An AFM probe is used to scan the cell membrane for nano sized features that may indicate cell functioning.