MicroRNAs (miRNAs) are a class of small non-coding RNAs that have emerged as potential predictive, prognostic, and therapeutic biomarkers, relevant to many pathophysiological conditions including limb immobilization, osteoarthritis, sarcopenia, and cachexia. Impaired musculoskeletal homeostasis leads to distinct muscle atrophies. Understanding miRNA involvement in the molecular mechanisms underpinning conditions such as muscle wasting may be critical to developing new strategies to improve patient management. MicroRNAs are powerful post-transcriptional regulators of gene expression in muscle and, importantly, are also detectable in the circulation. MicroRNAs are established modulators of muscle satellite stem cell activation, proliferation, and differentiation, however, there have been limited human studies that investigate miRNAs in muscle wasting. This narrative review summarizes the current knowledge as to the role of miRNAs in the skeletal muscle differentiation and atrophy, synthesizing the findings of published data. Cite this article:
Sarcopenia is an ageing-related disease featured by the loss of skeletal muscle quality and function. Advanced glycation end-products (AGEs) are a complex set of modified proteins or lipids by non-enzymatic glycosylation and oxidation. The formation of AGEs is irreversible, and they accumulate in tissues with increasing age. Currently, AGEs, as a biomarker of ageing, are viewed as a risk factor for sarcopenia. AGE accumulation could cause harmful effects in the human body such as elevated inflammation levels, enhanced oxidative stress, and targeted glycosylation of proteins inside and outside the cells. Several studies have illustrated the pathogenic role of AGEs in sarcopenia, which includes promoting skeletal muscle atrophy, impairing
Rotator cuff muscle atrophy and fatty infiltration affect the clinical outcomes of rotator cuff tear patients. However, there is no effective treatment for fatty infiltration at this time. High-intensity interval training (HIIT) helps to activate beige adipose tissue. The goal of this study was to test the role of HIIT in improving muscle quality in a rotator cuff tear model via the β3 adrenergic receptor (β3AR). Three-month-old C57BL/6 J mice underwent a unilateral rotator cuff injury procedure. Mice were forced to run on a treadmill with the HIIT programme during the first to sixth weeks or seventh to 12th weeks after tendon tear surgery. To study the role of β3AR, SR59230A, a selective β3AR antagonist, was administered to mice ten minutes before each exercise through intraperitoneal injection. Supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat were harvested at the end of the 12th week after tendon tear and analyzed biomechanically, histologically, and biochemically.Aims
Methods
This study explored the shared genetic traits and molecular interactions between postmenopausal osteoporosis (POMP) and sarcopenia, both of which substantially degrade elderly health and quality of life. We hypothesized that these motor system diseases overlap in pathophysiology and regulatory mechanisms. We analyzed microarray data from the Gene Expression Omnibus (GEO) database using weighted gene co-expression network analysis (WGCNA), machine learning, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to identify common genetic factors between POMP and sarcopenia. Further validation was done via differential gene expression in a new cohort. Single-cell analysis identified high expression cell subsets, with mononuclear macrophages in osteoporosis and muscle stem cells in sarcopenia, among others. A competitive endogenous RNA network suggested regulatory elements for these genes.Aims
Methods
Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells. HDACis were added to FAPs and satellite cell cultures isolated from mice. The HDACi vorinostat was additionally administered into a RC injury animal model. Histological analysis was carried out on the isolated supra- and infraspinatus muscles to assess vorinostat anti-muscle degeneration potential.Aims
Methods
Rotator cuff tear (RCT) is the leading cause of shoulder pain, primarily associated with age-related tendon degeneration. This study aimed to elucidate the potential differential gene expressions in tendons across different age groups, and to investigate their roles in tendon degeneration. Linear regression and differential expression (DE) analyses were performed on two transcriptome profiling datasets of torn supraspinatus tendons to identify age-related genes. Subsequent functional analyses were conducted on these candidate genes to explore their potential roles in tendon ageing. Additionally, a secondary DE analysis was performed on candidate genes by comparing their expressions between lesioned and normal tendons to explore their correlations with RCTs.Aims
Methods
Objectives. Traumatic brachial plexus injury causes severe functional impairment
of the arm. Elbow flexion is often affected. Nerve surgery or tendon
transfers provide the only means to obtain improved elbow flexion.
Unfortunately, the functionality of the arm often remains insufficient.
Stem cell therapy could potentially improve muscle strength and
avoid muscle-tendon transfer. This pilot study assesses the safety
and regenerative potential of autologous bone marrow-derived mononuclear
cell injection in partially denervated biceps. Methods. Nine brachial plexus patients with insufficient elbow flexion
(i.e., partial denervation) received intramuscular escalating doses
of autologous bone marrow-derived mononuclear cells, combined with
tendon transfers. Effect parameters included biceps biopsies, motor
unit analysis on needle electromyography and computerised muscle tomography,
before and after cell therapy. Results. No adverse effects in vital signs, bone marrow aspiration sites,
injection sites, or surgical wound were seen. After cell therapy
there was a 52% decrease in muscle fibrosis (p = 0.01), an 80% increase
in myofibre diameter (p = 0.007), a 50% increase in satellite cells
(p = 0.045) and an 83% increase in capillary-to-myofibre ratio (p
<
0.001) was shown. CT analysis demonstrated a 48% decrease in
mean muscle density (p = 0.009). Motor unit analysis showed a mean
increase of 36% in motor unit amplitude (p = 0.045), 22% increase
in duration (p = 0.005) and 29% increase in number of phases (p
= 0.002). Conclusions. Mononuclear cell injection in partly denervated muscle of brachial
plexus patients is safe. The results suggest enhanced
Developmental dysplasia of the hip (DDH) is a complex musculoskeletal disease that occurs mostly in children. This study aimed to investigate the molecular changes in the hip joint capsule of patients with DDH. High-throughput sequencing was used to identify genes that were differentially expressed in hip joint capsules between healthy controls and DDH patients. Biological assays including cell cycle, viability, apoptosis, immunofluorescence, reverse transcription polymerase chain reaction (RT-PCR), and western blotting were performed to determine the roles of the differentially expressed genes in DDH pathology.Aims
Methods
Rotator cuff tears are among the most frequent upper extremity injuries. Current treatment strategies do not address the poor quality of the muscle and tendon following chronic rotator cuff tears. Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor that activates many genes that are important in skeletal muscle regeneration. HIF-1α is inhibited under normal physiological conditions by the HIF prolyl 4-hydroxylases (PHDs). In this study, we used a pharmacological PHD inhibitor, GSK1120360A, to enhance the activity of HIF-1α following the repair of a chronic cuff tear, and measured muscle fibre contractility, fibrosis, gene expression, and enthesis mechanics. Chronic supraspinatus tears were induced in adult rats, and repaired 28 days later. Rats received 0 mg/kg, 3 mg/kg, or 10 mg/kg GSK1120360A daily. Collagen content, contractility, fibre type distribution and size, the expression of genes involved in fibrosis, lipid accumulation, atrophy and inflammation, and the mechanical properties of the enthesis were then assessed two weeks following surgical repair.Objectives
Methods
Rotator cuff tears are among the most common and debilitating
upper extremity injuries. Chronic cuff tears result in atrophy and
an infiltration of fat into the muscle, a condition commonly referred
to as ‘fatty degeneration’. While stem cell therapies hold promise
for the treatment of cuff tears, a suitable immunodeficient animal
model that could be used to study human or other xenograft-based
therapies for the treatment of rotator cuff injuries had not previously
been identified. A full-thickness, massive supraspinatus and infraspinatus tear
was induced in adult T-cell deficient rats. We hypothesised that,
compared with controls, 28 days after inducing a tear we would observe
a decrease in muscle force production, an accumulation of type IIB
fibres, and an upregulation in the expression of genes involved
with muscle atrophy, fibrosis and inflammation.Objectives
Methods
The goal of this study was to determine whether intra-articular
administration of the potentially anti-fibrotic agent decorin influences
the expression of genes involved in the fibrotic cascade, and ultimately
leads to less contracture, in an animal model. A total of 18 rabbits underwent an operation on their right knees
to form contractures. Six limbs in group 1 received four intra-articular
injections of decorin; six limbs in group 2 received four intra-articular
injections of bovine serum albumin (BSA) over eight days; six limbs
in group 3 received no injections. The contracted limbs of rabbits
in group 1 were biomechanically and genetically compared with the
contracted limbs of rabbits in groups 2 and 3, with the use of a
calibrated joint measuring device and custom microarray, respectively.Objectives
Methods
Lower limb muscle power is thought to influence outcome following
total knee replacement (TKR). Post-operative deficits in muscle
strength are commonly reported, although not explained. We hypothesised
that post-operative recovery of lower limb muscle power would be
influenced by the number of satellite cells in the quadriceps muscle at
time of surgery. Biopsies were obtained from 29 patients undergoing TKR. Power
output was assessed pre-operatively and at six and 26 weeks post-operatively
with a Leg Extensor Power Rig and data were scaled for body weight.
Satellite cell content was assessed in two separate analyses, the
first cohort (n = 18) using immunohistochemistry and the second
(n = 11) by a new quantitative polymerase chain reaction (q-PCR)
protocol for Pax-7 (generic satellite cell marker) and Neural Cell
Adhesion Molecule (NCAM; marker of activated cells).Objectives
Methods
