Development of Functional Bioengineered Muscle Models and a Novel Micro-Perfusion System.

Abstract

Tissue engineering combines the principles of medical, life science, and engineering fields toward the development of biological substitutes to restore, maintain, or improve tissue function. Previous work has demonstrated the feasibility of bioengineering smooth muscle tissue in vitro; however the contractile properties of bioengineered smooth muscle tissue have not been evaluated. It is imperative that bioengineered tissues have a high degree of functional testing in order to evaluate tissue-specific function as well as suitability for future clinical applications. This research describes the development and functional testing of novel 3-dimensional bioengineered smooth muscle tissues in vitro and the development of a micro-perfusion system to support culture and enhance functionality of bioengineered tissues. All bioengineered tissue models described here were developed utilizing a fibrin biomaterial, which is well-suited for bioengineering contractile tissues. We developed ring-shaped models of rat sphincter and colonic smooth muscle tissue as well as a strip model of human aortic vascular smooth muscle tissue. Functional testing of the contractile properties of bioengineered muscle tissues was accomplished using a custom build force transducer. Bioengineered tissues exhibited striking tissue-specific functionality, which was similar to smooth muscle in vivo, including the generation of spontaneous basal tone and agonist-induced contraction and relaxation, which was calcium-dependent and calcium-independent (respectively). Finally, in order to support the increased metabolic demands of bioengineered tissues, we designed and fabricated a novel micro-perfusion system to promote delivery of a constant supply of oxygenated media to bioengineered tissues. We tested the compatibility of our micro-perfusion system with Bioengineered Heart Muscle (BEHM) and found that the system is capable of supporting viability (mitochondrial activity, total protein, total RNA) and maintaining contractile properties (twitch force, specific force, electrical pacing, and expression of contractile proteins) of bioengineered tissues. In addition, short-term exposure of BEHMs to micro-perfusion resulted in some functional improvement. This research specifically adds to the knowledge base of two critical areas in tissue engineering research: 1) the development of functional bioengineered models, and 2) ancillary technology to support these models. Collectively, this research bridges several scientific and technological gaps in the field of functional tissue engineering.