Reconstitution of the Frank-Starling Mechanism in Engineered Heart Tissues

Abstract

According to the Frank-Starling mechanism, as the heart is stretched, it increases its contraction force. Reconstitution of the Frank-Starling mechanism is an important milestone for producing functional heart tissue constructs. Spontaneously contracting engineered heart tissues (EHTs) were reconstituted by growing dissociated chicken embryo cardiomyocytes in collagen matrices. Twitch and baseline tensions were recorded at precisely controlled levels of tissue strain. The EHTs showed a steep increase in twitch tension from 0.47 +/- 0.02 to 0.91 +/- 0.02 mN/mm2 as they were stretched at a constant rate (2.67% per min) from 86% to 100% of the length at which maximum twitch force was exerted. In response to a sudden stretch (3.3%), the twitch tension increased gradually (approximately 60 s) in a Gd3+-sensitive manner, suggesting the presence of stretch-activated Ca2+ channels. A large difference in baseline tension between lengthening (loading) and shortening (unloading) was also recorded. Disruption of nonsarcomeric actin filaments by cytochalasin D and latrunculin B decreased this difference. A simple mechanical model interprets these results in terms of mechanical connections between myocytes and nonmuscle cells. The experimental results strongly suggest that regulation of twitch tension in EHTs is similar to that of natural myocardium.

Whole cell mechanics of contractile fibroblasts: relations between effective cellular and extracellular matrix moduli

“…Bell et al 1979;Kolodney & Wysolmerski 1992;Asnes et al 2006;Griffith & Swartz 2006). Contractile fibroblast cells within a collagen gel can remodel and compact the collagen ECM around them, resulting in a stiffening of the tissue construct (Isenberg & Tranquillo 2003;Pryse et al 2003;Marquez et al 2006b).…”

Rapid Prototyping of Engineered Heart Tissues through Miniaturization and Phenotype-Automation

“…To systematically screen and analyze a large number of parameters that determine tissue function, the size of ETs has to be defined based on the required throughputs and phenotying assays for the tissue function analysis. Fully-grown cardiac muscle cells in three dimensional matrices are at least 100 um in length along their longitudinal axis [5]. Therefore, engineered heart tissues (EHTs) should be at least several times larger than the size of single cells in order to form multi-cellular functional cardiac muscles.…”

“…Assessment of acute and chronic changes in contractility and cell physiology can thus be www.intechopen.com monitored for long periods using EHTs. Even though EHTs are artificially reconstituted organoids, their histological structure and functional properties are similar to those in native myocardium [5,36]. Each EHT is fabricated by pouring a gel solution containing predefined concentrations of cells, matrix proteins, and growth factors into a precisely machined well [5].…”

“…Even though EHTs are artificially reconstituted organoids, their histological structure and functional properties are similar to those in native myocardium [5,36]. Each EHT is fabricated by pouring a gel solution containing predefined concentrations of cells, matrix proteins, and growth factors into a precisely machined well [5]. Since 1993, similar engineered tissues have been used as a model system to study signal transduction pathways that regulate contractility of fibroblasts [37], smooth muscle cells, skeletal muscle cells [8].…”

“…Recently, we introduced the concept of growing mini-tissues in 96-well plates for high-throughput drug screening [42]. Initially engineered heart tissues were fabricated using a tissue fabrication mold that cast hydrogel into a ring [5]. To miniaturize the tissues, we developed tissue fabrication wells similar to those used in 96-well format.…”