Researchers have studied the structure of a nanofibrous scaffold, as well as its interaction with rat cardiac cells. The study, which is part of the research into heart tissue regeneration, revealed that cardiomyocytes, the heart muscle cells, envelop nanofibers as they grow, while fibroblasts, which are connective tissue cells, tend to spread out on fibers forming several focal adhesion sites. The study was published in the journal Acta Biomaterialia.

Regenerative medicine seeks to repair or replace lost or damaged human cells, tissues, and organs. Tissue engineering is often the only way to restore the functions of the human heart and achieve recovery. Creating "patches" for a damaged heart demands more than merely understanding the properties of the corresponding tissue cells: One also needs to study their interaction with the substrate, as well as with the surrounding solution and the neighboring cells.

Getting the right scaffold is half the battle

Nanofibers may vary in terms of elasticity and electrical conductivity, or they may have additional "smart" functions allowing them to release biologically active molecules at a certain stage. Nanofibers are designed to mimic the extracellular matrix, which surrounds the cells, providing structural support.

The team conducted a three-stage study to determine the structural features of cardiac cells as well as the nature of their interaction with the fibers. First, they studied the structure of cardiomyocytes and fibroblasts grown on a substrate of nanofibers using confocal laser scanning microscopy. The tiniest sections of the cell were illuminated and scanned point-by-point allowing for the reconstruction of 3-D structures in the micrometric range.

The structure of cardiomyocytes and fibroblasts as well as that of the fiber was pre-stained with fluorescent antibodies. The obtained 3-D images showed that both types of the studied cells were aligned along the fibers and had spindle-like shapes. However, this data was insufficient to study the cell-fiber interface.

Cardiomyocytes have better adhesion to the substrate than fibroblasts

The researchers observed some important aspects of the cell-fiber interaction. First, since stronger mechanical adhesion i.e., cell-scaffold attachment means cells are more stable growing on the substrate, cardiomyocytes will be firmly attached to the scaffold, while fibroblasts will be less stable.

Secondly, additional "smart" scaffold functions, such as the release of growth factors protein molecules that stimulate cellular growth will also differ depending on the cell type.

Thirdly, cardiomyocytes isolate the polymer fibers from the surrounding solution. Since cardiomyocytes are responsible for the transfer of electromagnetic waves within the heart and therefore for heart contractions immersing the fibers of the scaffold completely in cardiomyocytes will enable researchers to test the electrical conductivity of the cells.

In further study, researchers estimated the mechanisms of cell-substrate interactions, will enable the creation of nanofibers that would provide cells with the properties needed to form regenerative tissues..