Articles Cell and Tissue Models

In Vitro Cellular & Developmental Biology - Animal

, Volume 42, Issue 3, pp 75-82

First online:

Functional evaluation of nerve-skeletal muscle constructs engineered in vitro

  • Lisa M. LarkinAffiliated withDepartment of Biomedical Engineering, University of MichiganDivision of Geriatric Medicine, University of MichiganMuscle Mechanics Laboratory, University of Michigan Email author 
  • , Jack H. van der MeulenAffiliated withMuscle Mechanics Laboratory, University of Michigan
  • , Robert G. DennisAffiliated withDepartment of Biomedical Engineering, University of MichiganDepartment of Mechanical Engineering, University of MichiganDepartment of Biomedical Engineering, University of North Carolina at Chapel Hill
  • , Jeffrey B. KennedyAffiliated withMuscle Mechanics Laboratory, University of Michigan

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Summary

Previously, we have engineered three-dimensional (3-D) skeletal muscle constructs that generate force and display a myosin heavy-chain (MHC) composition of fetal muscle. The purpose of this study was to evaluate the functional characteristics of 3-D skeletal muscle constructs cocultured with fetal nerve explants. We hypothesized that coculture of muscle constructs with neural cells would produce constructs with increased force and adult MHC isoforms. Following introduction of embryonic spinal cord explants to a layer of confluent muscle cells, the neural tissue integrated with the cultured muscle cells to form 3-D muscle constructs with extensions. Immunohistochemical labeling indicated that the extensions were neural tissue and that the junctions between the nerve extensions and the muscle constructs contained clusters of acetylcholine receptors. Compared to muscles cultured without nerve explants, constructs formed from nerve-muscle coculture showed spontaneous contractions with an increase in frequency and force. Upon field stimulation, both twitch (2-fold) and tetanus (1.7-fold) were greater in the nerve-muscle coculture system. Contractions could be elicited by electrically stimulating the neural extensions, although smaller forces are produced than with field stimulation. Severing the extension eliminated the response to electrical stimulation, excluding field stimulation, as a contributing factor. Nervemuscle constructs showed a tendency to have higher contents of adult and lower contents of fetal MHC isoforms, but the differences were not significant. In conclusion, we have successfully engineered a 3-D nerve-muscle construct that displays functional neuromuscular junctions and can be electrically stimulated to contract via the neural extensions projecting from the construct.

Key words

myooid coculture neuromuscular junction