Mechanobiology of Cardiomyocytes

Adhesive micropatterns have been used by Yasha Kresh's and Paul Janmey’s group at Drexel University / University of Pennsylvania to demonstrate the ability of cardiac cells to remodel their cytoskeletal organization and shape, including sarcomere/myofibrillar architectural topography. 

The images were created by Dr. Erdem Tabdanov, a former Postdoctoral Fellow in their Lab.

The cardiomyocyte exhibits constant mechanosensory-regulated adjustment of its cytoskeleton through tight
interplay between its force generation activity and concurrent intra cellular architectural remodeling.

Neonatal rat cardiac myocytes (NVRM) on the Starter's micropatterns

When presented with a variety of isotropic and multiaxial anisotropic geometries (O, H, Y, T), they observed a uniquely characteristic and sensitive myofibrillar self-assembly response. The myofibrillar structures preserved their 2D coherence throughout the cell, forming a 2D material continuum (even over voided spaces) as opposed to the one-dimensional tensional
integrity seen in stress fibers (Figure below). The self-generated contractile stress field gave rise to myofibril organization responsible for the dominant contractile forces acting along the fibers. The contraction-induced compaction, acting transverse to the myofibril, appears to drive the assembly of sarcomeres.

By merely manipulating ECM adhesion topography, cardiac cells are able to precisely adapt their cytoskeleton architecture to the
geometry of their microenvironment. As seen in many other adhesive types of cells, remodeling of the cytoskeleton structures
(actin, microtubule networks) contributes to the adaptation of the entire cell polarity with respect to externally imposed constraints

These observations provide an important insight into a controllable parameter to help engineer functional cardiac tissues.