Cell contacts and cross-talk: Conversion into cardiomyocytes

Cardiovascular diseases (CVD) are one of the leading causes of death in nearly all countries of Europe. New strategies for therapy are highly desirable since treatment options for heart failure caused by CVD are still inadequate. Therefore, stem cells are a promising option for cell therapy in cardiology. Despite the human heart possesses a pool of cardiac stem cells, their percentage is too small to regenerate sufficient myocardial tissue after a myocardial infarct. So far, stem cells of different origins were tested for cardiac cell therapy. Based on hopeful in vivo experiments, clinical trials were done, but most transplanted cells failed to integrate. Therefore, there is need for more basic research to clarify the mechanisms and requirements for functional integration and conversion. Mesenchymal stem cells (MSCs) from placenta (PMSCs) are a new source of cells for cell therapy. MSCs commonly display positive features for immunoregulation and neovascularisation. PMSCs additionally show a basic cardiomyocytic (CMC) phenotype. Hence these cells appear to be the perfect type of MSCs for cardiac cell therapy. Moreover, for successful integration and conversion appropriate cell communication is indispensable. During conversion events, direct cell-cell contact and exchange of cell components are essential. Recently the exchange of macromolecules and organells (mitochondria) via tunnelling nanotubes was confirmed. However, detailed information about transferred cellular components and their function are missing. So, the proposed project will set up an in vitro co-culture system of PMSCs and CMCs. Control experiments will be done in parallel with MSCs from bone marrow. The focus will be on 4 main topics: (1) Efficiency of conversion; (2) Structure and identification of cell-cell contacts; (3) Identity of transferred cell components (cross- talk); (4) Genes involved in conversion event. Consequential co-cultured cells were checked for conversion by immunocytochemical stainings (ICC), RNA isolation, followed by RT-PCR, western blot analysis and functional test. Cell-cell contacts will be visualized by ICC and transmission electron microscopy. Cross-talk of cells will be demonstrated by using Fluorescent dye transfer assay and Mito-Tracking. Gene chip analysis will be performed for verification of changes on RNA-level and to determine involved genes. The outcome will point out if PMSCs are suitable for cardiac cell therapy. Furthermore the identification of involved genes will contribute to our understanding of the molecular mechanisms that regulate conversion into CMCs. This knowledge is important for investigating and optimizing of further conversion or application strategies in cells. This work should build the basis for follow up studies with focus on genomics and proteomics in the field of cell conversion events.

Cardiovascular diseases are one of the leading causes of death in nearly all countries of Europe. Regenerative Medicine using mesenchymal stem cells are a promising option in cardiology. But there is still the need for more basic research to clarify the mechanisms and requirements for functional integration and differentiation/conversion. Goal of the proposed project was to clarify if mesenchymal stem cells from amnion (AMSCs), the inner layer of the placenta of fetal origin, are superior to commonly used bone marrow derived mesenchymal stem cells (BMSCs). The focus was on direct cell-cell contact and exchange of cell components like macromolecules and organells (cross-talk). Because cell-cell contacts are essential for integration and differentiation, a special focus was on cell connection called tunneling nanotubes (TNTs). Within experiments in cell culture, AMSCs or BMSCs were cultivated together with cardiomyocytes. Using fluorescence dyes, TNTs could be visualized and evaluated. Data were gained, suggesting that AMSCs are more likely to build TNTs than BMSCs. These data support the hypothesis, that AMSCs are more suitable for cardiac cell therapy than BMSCs.