Functional Development of Engineered Skeletal Muscle from Adult and Neonatal Rats

A myooid is a three-dimensional skeletal muscle construct cultured from mammalian myoblasts and fibroblasts. The purpose was to compare over several weeks in culture the morphology, excitability, and contractility of myooids developed from neonatal and adult rat cells. The hypotheses tested were as follows: (1) baseline forces of myooids correlate with the cross-sectional area (CSA) of the myooids composed of fibroblasts, and (2) peak isometric tetanic forces normalized by total CSA (specific Po) of neonatal and adult rat myooids are not different. Electrical field stimulation was used to measure the excitability and peak tetanic forces. The proportion of the CSA composed of fibroblasts was greater for neonatal (40%) than adult (17%) myooids. For all myooids the baseline passive force normalized by fibroblast CSA (mean = 5.5 kPa) correlated with the fibroblast CSA (r2 = 0.74). A two-element cylindrical model was analyzed to determine the contributions of fibroblasts and myotubes to the baseline force. At each measurement period, the specific Po of the adult myooids was greater than that of the neonatal myooids. The specific Po of the adult myooids was ~1% of the control value for adult muscles and did not change with time in culture, while that of neonatal myooids increased.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63318/1/107632701753213192.pd

Challenges in Cardiac Tissue Engineering

Cardiac tissue engineering aims to create functional tissue constructs that can reestablish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell—the actual “tissue engineer”—is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure