Bioreactor for modulation of cardiac microtissue phenotype by combined static stretch and electrical stimulation

Abstract

We describe here a bioreactor capable of simultaneously applying mechanical and electrical field stimulation in conjunction with static strain and on-line force of contraction measurements. It consisted of a polydimethylsiloxane (PDMS) tissue chamber and a pneumatically driven stretch platform. The chamber contained eight tissue microwells (8.05 mm in length and 2.5 mm in width) with a pair of posts (2.78 mm in height and 0.8 mm in diameter) in each well to serve as fixation points and for measurements of contraction force. Carbon rods, stimulating electrodes, were placed into the PDMS chamber such that one pair stimulated four microwells. For feasibility studies, neonatal rat cardiomyocytes were seeded in collagen gels into the microwells. Following three days of gel compaction, electrical field stimulation at 3–4 V/cm and 1Hz, mechanical stimulation of 5% static strain or electromechanical stimulation (field stimulation at 3–4 V/cm, 1Hz and 5% static strain) were applied for 3 days. Cardiac microtissues subjected to electromechanical stimulation exhibited elevated amplitude of contraction and improved sarcomere structure as evidenced by sarcomeric α-actinin, actin and troponin T staining compared to microtissues subjected to electrical or mechanical stimulation alone or non-stimulated controls. The expression of atrial natriuretic factor and brain natriuretic peptide was also elevated in the electromechanically stimulated group.

In vitro cardiac tissue models: Current status and future prospects

“…The biowire maturation represented an intermediate phenotype as CMs undergo maturation from the embryonic state, as evidenced by low membrane conductance. The use of electrical stimulation in conjunction with stretch as a mimic of cardiac load, concurrently or sequentially, might be required to induce terminal differentiation and maturation in hiPSC-CMs [94, 95]. …”

The Role of Tissue Engineering and Biomaterials in Cardiac Regenerative Medicine

“…The results indicate the importance of combined electromechanical simulation and the selection of appropriate timing for stimulation (97). Similarly, Miklas et al (98) combined electrical pacing with static stretching and found improved sarcomere structure and increased contractile force.…”

Biomaterials for pluripotent stem cell engineering: from fate determination to vascularization

“…Electrical stimulation of these cell-laden structures led to increased myofibril organization and enhanced contractile and electrical properties compared to non-stimulated controls. Subsequent work, by the same group and others, has indicated that a combination of electrical stimulation and mechanical conditioning plays an important role in stem cell differentiation towards cardiac cells as well as cardiac tissue maturation (65, 66) . Biomaterials can contribute significantly to this effort by facilitating the integration of electrical and mechanical cues in 3D stem cell cultures (67) .…”