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Effects of Dexamethasone on Tissue Engineered Skeletal Muscle Units
Author(s) -
Larson Alexie
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1300.12
Subject(s) - myod , myogenesis , myogenin , skeletal muscle , myocyte , cardiotoxin , immunostaining , myogenic regulatory factors , chemistry , muscle atrophy , myosin , dexamethasone , andrology , myf5 , medicine , endocrinology , biology , immunohistochemistry , biochemistry
Volumetric muscle loss (VML), muscular trauma that overwhelms the native repair mechanism, necessitates surgical intervention. Limitations to current VML treatments present a need for exogenous graft muscle sources. To date, engineered muscle produces forces substantially lower than native muscle, limiting its potential for repair. In this study, we examined the trophic effects of dexamethasone (DEX), a glucocorticoid that stimulates myoblast differentiation and fusion into myotubes, on our tissue engineered skeletal muscle units (SMUs). Using our established SMU fabrication protocol, muscle isolates were exposed to two DEX concentrations (10 and 25 nM). Following seeding onto a laminin‐coated Sylgard substrate, DEX addition was initiated on day 0 until the first feeding of growth media (day 4), or sustained until SMU formation as a control (days 0–20). Cell proliferation was measured with a BrdU assay (day 4), and myogenesis was observed through immunostaining for MyoD (day 4), and α‐actinin (day 11). After SMU formation (day 20), isometric tetanic force production was recorded to quantify functional improvement. The sustained addition of 10 nM DEX yielded optimal SMUs with advanced structural maturity and functionality. Though 25 nM DEX administered days 0–4 showed a 12% increase in myogenic proliferation determined by a BrdU and MyoD co‐stain at day 4, by day 11 the SMUs with sustained addition of 10 nM DEX demonstrated the greatest advancement in sarcomeric structure observed by α‐actinin immunostaining and a 2‐fold rise in myotube density determined by light microscopy analysis on day 14, compared to both 10 nM and 25 nM DEX days 0–4 groups. Additionally, the SMUs with sustained 10 nM DEX exhibited a 16% increase in force production compared to both 10 nM and 25 nM DEX days 0–4 groups. Future research will focus on further investigation of the timing of DEX addition, understanding the mechanism behind these effects and evaluating the regenerative potential of these SMUs in vivo. Support or Funding Information Supported by NIH/NIAMS 1R01AR067744‐01