Bioreactor Platform for Biomimetic Culture and in situ Monitoring of the Mechanical Response of in vitro Engineered Models of Cardiac Tissue

Abstract

In the past two decades, relevant advances have been made in the generation of engineered cardiac constructs to be used as functional in vitro models for cardiac research or drug testing, and with the ultimate but still challenging goal of repairing the damaged myocardium. To support cardiac tissue generation and maturation in vitro , the application of biomimetic physical stimuli within dedicated bioreactors is crucial. In particular, cardiac-like mechanical stimulation has been demonstrated to promote development and maturation of cardiac tissue models. Here, we developed an automated bioreactor platform for tunable cyclic stretch and in situ monitoring of the mechanical response of in vitro engineered cardiac tissues. To demonstrate the bioreactor platform performance and to investigate the effects of cyclic stretch on construct maturation and contractility, we developed 3D annular cardiac tissue models based on neonatal rat cardiac cells embedded in fibrin hydrogel. The constructs were statically pre-cultured for 5 days and then exposed to 4 days of uniaxial cyclic stretch (sinusoidal waveform, 10% strain, 1 Hz) within the bioreactor. Explanatory biological tests showed that cyclic stretch promoted cardiomyocyte alignment, maintenance, and maturation, with enhanced expression of typical mature cardiac markers compared to static controls. Moreover, in situ monitoring showed increasing passive force of the constructs along the dynamic culture. Finally, only the stretched constructs were responsive to external electrical pacing with synchronous and regular contractile activity, further confirming that cyclic stretching was instrumental for their functional maturation. This study shows that the proposed bioreactor platform is a reliable device for cyclic stretch culture and in situ monitoring of the passive mechanical response of the cultured constructs. The innovative feature of acquiring passive force measurements in situ and along the culture allows monitoring the construct maturation trend without interrupting the culture, making the proposed device a powerful tool for in vitro investigation and ultimately production of functional engineered cardiac constructs.

Dynamic flow priming programs allow tuning up the cell layers properties for engineered vascular graft

“…Moreover, since normal blood vessels are constantly exposed to blood flow, it is particularly important to consider the effect of mechanical stimulation during in vitro culture 22 . Bioreactor-based culture systems hold the potential to provide a testing platform that is more predictable of a whole tissue response by providing more physiologically relevant conditions comparing to customarily used two- and three-dimensional cultures 23 , 24 . Here we proposed a novel method to create three-layered TEVG with biocompatible glass fibers as supporting scaffold and to train a tissue by the developed bioreactor system.…”

Cardiac Organoids to Model and Heal Heart Failure and Cardiomyopathies

“…They obtained well-formed tissues showing a positive force–frequency relationship and post-rest potentiation. Other bioreactors allowing for dynamic and mechanical stretching of engineered microtissues could also be built to further improve the maturation of the tissues [ 174 ]. This precise monitoring of the mechanical load exerted on the tissues enabled Pitoulis et al to recreate the electromechanical events of in vivo pressure–volume loops with in vitro force–length loops [ 175 ].…”

Recent Advances in Maturation of Pluripotent Stem Cell-Derived Cardiomyocytes Promoted by Mechanical Stretch

“…Importantly, if these tests need separation between cells and their culture environment, the outcomes may incorrectly reflect the in situ states of PSC-CMs. Some specific devices have been developed to realize in situ monitoring of cellular functions to solve this problem [ 50 , 51 ]. Moreover, for some drugs such as isoproterenol, hESC-CMs respond to the drugs in a similar manner to native cardiomyocytes, with corresponding increases or decreases in contractile force observed [ 31 , 52 ].…”