Third party funded individual grant
Start date : 01.01.2014
End date : 31.12.2015
Cardiac remodeling limits cardiac function in hypertrophic cardiac diseases usually associated with increase in extracellular matrix. However, also cellular remodeling occurs that may be triggered via mechanosensitive pathways involving, e.g. transient receptor potential channels, Ca2+ signaling and differential regulation of growth pathways. Mechanisms of Ca2+-induced hypertrophic cardiomyopathy (HCM) are not clarified in detail but aberrant increase in diastolic filling pressure may upregulate TRPC expression to conduct Ca2+ through stretch-activation. In cardiomyocytes, a direct stretch-sensitivity of TRPC channels has not been shown so far. This is mostly due to non-specific blockers used as well as conceptual differences in the pathological stretch-regime in vivo and in vitro. Most stretch devices apply uniaxial stretch to myocytes, while an isotropic stretch-regime would better reflect the situation in the heart. Our project will bridge between biotechnological device development for improved cardiomyocyte research and the elucidation of the involvement of TRPC channel isoforms in the development of HCM. Specific aims are:
1) To engineer a novel cell stretch device for isotropic rather than uniaxial stretch protocols on isolated cardiomyocytes (CM) coated on PDMS membranes
2) To implement mechatronics and electronics support to tenable fully automated, long-term stretch recordings on stage of a microscope
3) To record Ca2+ levels in single cardiomyocytes coated onto PDMS membranes, stretched to various percentages of isotropic circular stretch using maintained static as well as cyclic stretch at different duty cycles mimicking a normal heart beat
4) To unravel the source of stretch-induced Ca2+ entry as store-operated, voltage sensitive, NCX pathway, plasmalemma Ca-ATPase or mechanosensitive using appropriate and sequential blockers (i.e. novel pore-blocking anti-TRPC antibodies to block TRPC channels)
5) To apply the technology to wt and single CMs from mice after transaortic constriction (TAC) to induce HCM. TRPC channel expression profiles are assessed