Bioengineering approaches to promote maturity in human skeletal muscle constructs

Abstract

In 2021/22, the MicroAge project, a UK Space Agency-funded mission, sent 3D muscle constructs to the International Space Station to study microgravity as a model of accelerated musculoskeletal ageing on Earth. The aim of this work is to further develop the muscle constructs, compromised of human skeletal muscle cells encapsulated in fibrin hydrogels, induced to differentiate into myotubes and grown in 3D. The study uses several bioengineering approaches to determine the extent of maturity achievable in these muscle constructs in vitro, with the aim of producing a pharmacological or physiological screening platform of mature muscle, targeting muscle disorders such as sarcopenia.To enable measurement of muscle functional properties, it was also necessary to develop a suitable surrogate for force generation due to constraints of strain gauge use, and so this study also determined whether electrochemical impedance spectroscopy (EIS) was appropriate in numerous instances, opening up possibilities for rapid and automated measurement of contractile properties of in vitro skeletal muscle models. This was undertaken by the development of the MicroAge culture system to allow simultaneous measurement of force characteristic using a micro stain gauge and EIS measurements via the stimulating electrodes.The MicroAge muscle constructs have been characterised using a panel of maturation indices for skeletal muscle, including measuring contractile properties, and myosin heavy chain isoform expression using immunocytochemistry with spinning disc microscopy, RT-qPCR and Western blotting and these data will be presented.Of particular interest are the data that demonstrated a linear relationship between force generation measured using the ‘gold-standard’ approach of using a strain gauge and EIS (R2 = 0.9), validating the use of EIS as a proxy for force generation in a range of conditions such as in muscle constructs at rest and during contraction.This allows for rapid and automated measurement of contractile properties of in vitro models of skeletal muscle, providing an exciting new platform to rapidly test pharmacological interventions that may result in improved muscle function in 3D models of disease. The study is also currently implementing bioprinting of muscle constructs to streamline construct formation and investigating varying patterns of electrical stimulation on construct maturity throughout differentiation and the results of this approach will also be presented. Supported by a PhD studentship from MRC DiMeN Doctoral Training Programme and CIMA. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.