Effects of Dexamethasone on Satellite Cells and Tissue Engineered Skeletal Muscle Units

Tissue engineered skeletal muscle has potential for application as a graft source for repairing soft tissue injuries, a model for testing pharmaceuticals, and a biomechanical actuator system for soft robots. However, engineered muscle to date has not produced forces comparable to native muscle, limiting its potential for repair and for use as an in vitro model for pharmaceutical testing. 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 three-dimensional skeletal muscle units (SMUs). Using our established SMU fabrication protocol, muscle isolates were cultured with three experimental DEX concentrations (5, 10, and 25?nM) and compared to untreated controls. Following seeding onto a laminin-coated Sylgard substrate, the administration of DEX was initiated on day 0 or day 6 in growth medium or on day 9 after the switch to differentiation medium and was sustained until the completion of SMU fabrication. During this process, total cell proliferation was measured with a BrdU assay, and myogenesis and structural advancement of muscle cells were observed through immunostaining for MyoD, myogenin, desmin, and α-actinin. After SMU formation, isometric tetanic force production was measured to quantify function. The histological and functional assessment of the SMU showed that the administration of 10?nM DEX beginning on either day 0 or day 6 yielded optimal SMUs. These optimized SMUs exhibited formation of advanced sarcomeric structure and significant increases in myotube diameter and myotube fusion index, compared with untreated controls. Additionally, the optimized SMUs matured functionally, as indicated by a fivefold rise in force production. In conclusion, we have demonstrated that the addition of DEX to our process of engineering skeletal muscle tissue improves myogenesis, advances muscle structure, and increases force production in the resulting SMUs.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140236/1/ten.tea.2015.0545.pd

Recovery of Male Reproductive Function After Ceasing Prolonged Testosterone Undecanoate Injections

Context: The time course of male reproductive hormone recovery after stopping injectable testosterone undecanoate (TU) treatment is not known.Objective: The aim of this study was to investigate the rate, extent, and determinants of reproductive hormone recovery over 12 months after stopping TU injections.Materials and Methods: Men (n = 303) with glucose intolerance but without pathologic hypogonadism who completed a 2-year placebo (P)-controlled randomized clinical trial of TU treatment were recruited for further 12 months while remaining blinded to treatment. Sex steroids (testosterone (T), dihydrotestosterone, oestradiol, oestrone) by liquid chromatography-mass sprectometry, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG) by immunoassays and sexual function questionnaires (Psychosexual Diary Questionnaire, International Index of Erectile Function, and short form survey (SF-12)) were measured at entry (3 months after the last injection) and 6, 12, 18, 24, 40, and 52 weeks later.Results: In the nested cohort of TU-treated men, serum T was initially higher but declined at 12 weeks remaining stable thereafter with serum T and SHBG at 11 and 13%, respectively, lower than P-treated men. Similarly, both questionnaires showed initial carry-over higher scores in T-treated men but after 18 weeks showed no difference between T- and P-treated men. Initially, fully suppressed serum LH and FSH recovered slowly towards the participant’s own pre-treatment baseline over 12 months since the last injection.Conclusions: After stopping 2 years of 1000 mg injectable TU treatment, full reproductive hormone recovery is slow and progressive over 15 months since the last testosterone injection but may take longer than 12 months to be complete. Persistent proportionate reduction in serum SHBG and T reflects lasting exogenous T effects on hepatic SHBG secretion rather than androgen deficiency.David J Handelsman, Reena Desai, Ann J Conway, Nandini Shankara-Narayana, Bronwyn G A Stuckey, Warrick J Inder, Mathis Grossmann, Bu Beng Yeap, David Jesudason, Lam P Ly, Karen Bracken, and Gary Allen Witter

Effect of Testosterone treatment on bone microarchitecture and bone mineral density in men: a two-year RCT

CONTEXT: Testosterone treatment increases bone mineral density (BMD) in hypogonadal men. Effects on bone microarchitecture, a determinant of fracture risk, are unknown. OBJECTIVE: Determine the effect of testosterone treatment on bone microarchitecture using high resolution-peripheral quantitative computed tomography (HR-pQCT). DESIGN, SETTING, PARTICIPANTS: Men>50 years were recruited from six Australian centres. INTERVENTIONS: Injectable testosterone undecanoate or placebo over 2 years on the background of a community-based lifestyle program. MAIN OUTCOMES: Primary endpoint was cortical volumetric BMD (vBMD) at the distal tibia, measured using HR-pQCT in 177 men (one centre). Secondary endpoints included other HR-pQCT parameters and bone remodelling markers. Areal BMD (aBMD) was measured by dual energy X-ray absorptiometry (DXA) in 601 men (five centres). Using a linear mixed model for repeated measures, the mean adjusted differences (MAD) [95% CI] at 12 and 24 months between groups are reported as treatment effect. RESULTS: Over 24 months, testosterone treatment, compared to placebo, increased tibial cortical vBMD), 9.33mgHA/cm 3[3.96;14.71],p50 years, testosterone treatment for 2 years increased volumetric bone density, predominantly via effects on cortical bone. Implications for fracture risk reduction require further study.Mark Ng Tang Fui, Rudolf Hoermann, Karen Bracken, David J Handelsman, Warrick J Inder, Bronwyn G A Stuckey ... et al