A novel miniaturized bioreactor for the generation, stimulation and observation of stem cell-derived 3d bioartificial cardiac tissue

Objectives: Three-dimensional (3D) cardiac tissue engineering is a promising means for regenerative therapies and for pharmacological testing in vitro. Cardiac cells can be differentiated from stem cells as, i.e. embryonic stem cells (ESC) and induced pluripotent stem (iPS) cells. Adjusted to low numbers of stem cell-derived cardiac cells we have designed a modular bioreactor system that allows for the generation of miniaturized Bioartificial Cardiac Tissue (BCT). Several factors can be manipulated to monitor their impact on the tissues. Mechanical stretch, electric stimulation and application of test compounds on the tissue can be assessed online in terms of force and frequency measurements of spontaneous or electrically induced contractions by highly precise sensors. Material and Methods: Neonatal rat cardiomyocytes (NRCM) were mixed with collagen type I and Matrigel and poured into custom-made Teflon molds (225 mu l / 9x5 mm). Mechanical and/or chemical stimulation was applied to BCTs and force measurements were performed from d7 to dl4. Cell distribution and sarcomer organization were assessed by immuno-fluorescence staining. Results and Conclusion: The tissues generated in our system displayed synchronized contractile activity and forces of up to 3.55 mN. Morphologically, they resembled native myocardium with aligned cardiomyocytes and well-developed sarcomeres. In conclusion, our novel bioreactor can be used to efficiently monitor BCT maturation in vitro and is an important tool for the implementation of stem cell-derived cardiomyocytes in small-scale cardiac tissue engineering.