Biology subjects

Hoerning, M.

Publications and source records attributed to Hoerning, M..

2 recordsLinked to original sources

bioRxiv2024

Optimization of H9c2 differentiation leads to calcium-active and striated cardiac cells without addition of retinoic acid.

As a reliable alternative to animal testing in cardiovascular research, it is crucial to improve differentiation of immortalized cell lines. In this study, we focused on optimizing the differentiation efficiency of the H9c2 cell line into cardiomyocytes using a high-throughput, automated image processing approach. While previous studies used protocols involving retinoic acid to enhance cardiac differentiation, we applied a simplified medium composition that results in higher differentiation rates. Along that line, we differentiated H9c2 cells into cardiomyocytes, which not only showed sarcomere-characteristic striation but also periodic intracellular calcium signaling for the first time. As a second step, we examined the potential application of polyacrylamide hydrogels (E = 12 kPa) with defined fibronectin coating densities. The optimum fibronectin density of 2.6 {micro}g/cm2 found for single cells was investigated to further improve the differentiation efficiency. However, the differentiation and proliferation dynamics dominate the adhesion forces between the cells and the hydrogel, and thus, result in premature clustering and detachment. In conclusion, we identified an optimized differentiation protocol and provided a basis for the further investigation necessary to potentially use hydrogels as natural cell environment, aiming to raise the differentiation efficiency even more.

developmental biology↗

bioRxiv2024

Self-organization of PIP3 signaling is controlled by the confinement, topology, and curvature of the cell membrane.

PIP3 is a signaling lipid on the plasma membrane that plays a fundamental role in cell signaling with a strong impact on cell physiology and diseases. It is responsible for the protruding edge formation, cell polarization, macropinocytosis and other membrane remodeling dynamics in cells. It has been shown that the membrane confinement and curvature affects the wave formation of PIP3 and Factin. But even in the absence of F-actin, a complex self-organization of the spatiotemporal PIP3 waves is observed. In recent findings, we have shown that these waves can be guided and pinned on strongly bended Dictyostelium membranes caused by molecular crowding and curvature limited diffusion. Based on these experimental findings, we investigate the spatiotemporal PIP3 wave dynamics on realist 3D cell-like membranes to explore the effect of curvature limited diffusion, as observed experimentally. We use an established stochastic reaction-diffusion model with enzymatic MichaelisMenten type reactions that mimics the dynamics of Dictyostelium cells. As these cells mimic the 3D shape and size observed experimentally, we found that the PIP3 wave directionality can be explained by a Hopf-like and a reverse periodic-doubling bifurcation for uniform diffusion and curvature limited diffusion properties. Finally, we compare the results with recent experimental findings and discuss the discrepancy between the biological and numerical results.

biophysics↗