Quantitative Evaluation of Cardiac Cell Interactions and Responses to Cyclic Strain

Abstract

The heart has a dynamic mechanical environment contributed by its unique cellular composition and the resultant complex tissue structure. In pathological heart tissue, both the mechanics and cell composition can change and influence each other. As a result, the interplay between the cell phenotype and mechanical stimulation needs to be considered to understand the biophysical cell interactions and organization in healthy and diseased myocardium. In this work, we hypothesized that the overall tissue organization is controlled by varying densities of cardiomyocytes and fibroblasts in the heart. In order to test this hypothesis, we utilized a combination of mechanical strain, co-cultures of different cell types, and inhibitory drugs that block intercellular junction formation. To accomplish this, an image analysis pipeline was developed to automatically measure cell type-specific organization relative to the stretch direction. The results indicated that cardiac cell type-specific densities influence the overall organization of heart tissue such that it is possible to model healthy and fibrotic heart tissue in vitro. This study provides insight into how to mimic the dynamic mechanical environment of the heart in engineered tissue as well as providing valuable information about the process of cardiac remodeling and repair in diseased hearts.

Human pluripotent stem cell-derived cardiomyocytes align under cyclic strain when guided by cardiac fibroblasts

“…These results indicate that the strain-induced alignment of CMs in co-culture with cFBs is not caused by paracrine signaling nor to Cx43 or N-cadherin mediated cell-cell communication between the CMs and cFBs. This is in line with a recent report showing a lack of Cx43 and N-cadherin-mediated cell-cell communication in the co-culture organization of neonatal rat CMs and cFBs [41]. Future experiments using targeted inhibition of Cx43 and N-cadherin in co-cultures under cyclic strain together with transcriptional analysis should be performed to validate these findings.…”

“…These results indicate that the strain-induced alignment of CMs in co-culture with cFBs is not caused by paracrine signaling nor to Cx43 or N-cadherin mediated cell-cell communication between the CMs and cFBs. This is in line with a recent report showing a lack of Cx43 and N-cadherinmediated cell-cell communication in the co-culture organization of neonatal rat CMs and cFBs [41].…”

“…Whereas, to our knowledge, no literature exists for human tissues or models on how the amount of cFBs modulates strain avoidance of CMs, a recent study by Tran et al demonstrated a cell density dependent response to cyclic strain for co-cultures of varying ratios of neonatal rat CMs and cFBs [41]. In contrast to hPSC-derived CMs, monocultures of neonatal rat CMs oriented along the direction of cyclic strain and increasing the amount of cFBs in the co-culture resulted in orientation away from the direction of the applied cyclic strain.…”

“…In contrast to hPSC-derived CMs, monocultures of neonatal rat CMs oriented along the direction of cyclic strain and increasing the amount of cFBs in the co-culture resulted in orientation away from the direction of the applied cyclic strain. However, a higher number of cFBs was needed to induce strain avoidance in neonatal rat CMs as opposed to in co-cultures of human cFBs and CMs derived from pluripotent stem cells, possibly due to differences in maturity and contractile state between the two types of CMs [41]. Moreover, several studies have investigated the contribution of the amount of cFBs on CM alignment and maturity.…”

Human pluripotent stem cell-derived cardiomyocytes align under cyclic strain when guided by cardiac fibroblasts

“…Dynamic reorganization and remodeling of actin stress fibers in combination with a nucleo-cytoskeletal connection are believed to play an important role in the cell type-dependent response to uniaxial cyclic strain (mechanoresponse). 23–25 While cFBs are consistent in their strain avoidance behavior, 26,27 CMs show inconsistent responses, 27–31 probably related to differences in their contractile state and actin organization. 32,33 To date, CM mechanoresponse remains largely unexplored, contributing to the controversy about how CMs respond to cyclic strain.…”