Effect of muscular exercise on patients with muscular dystrophy: A systematic review and meta-analysis of the literature

Background: Muscular dystrophy causes weakness and muscle loss. The effect of muscular exercise in these patients remains controversial. Objective: To assess the effects of muscular exercise vs. no exercise in patients with muscular dystrophy. Methods: We performed a comprehensive systematic literature search in the Medline, Embase, Web of Science, Scopus, and Pedro electronic databases, as well as in the reference literature. We included randomized clinical trials (RCTs) that reported the effect of muscular exercise on muscle strength, endurance during walking, motor abilities, and fatigue. Data were extracted independently by two reviewers. Mean difference (MD) and 95% confidence intervals (CI) were used to quantify the effect associated with each outcome. We performed pairwise meta-analyses and trial sequential analyses (TSA) and used GRADE to rate the overall certainty of evidence. Results: We identified 13 RCTs involving 617 patients. The median duration of exercise interventions was 16 weeks [interquartile range [IQR] 12-24]. In the patients with facio-scapulo-humeral dystrophy and myotonic dystrophy, no significant difference in extensor muscle strength was noted between the exercise and the control groups [four studies, 115 patients, MD 4.34, 95% CI -4.20 to 12.88, I2 = 69%; p = 0.32; minimal important difference [MID] 5.39 m]. Exercise was associated with improved endurance during walking [five studies, 380 patients, MD 17.36 m, 95% CI 10.91-23.81, I2 = 0; p < 0.00001; MID 34 m]. TSA excluded random error as a cause of the findings for endurance during walking. Differences in fatigue and motor abilities were small. Not enough information was found for other types of dystrophy. Conclusions: Muscular exercise did not improve muscle strength and was associated with modest improvements in endurance during walking in patients with facio-scapulo-humeral and myotonic dystrophy. Future trials should explore which type of muscle exercise could lead to better improvements in muscle strength. PROSPERO: CRD42019127456

Stem Cell-Derived Extracellular Vesicles and Immune-Modulation

Extra-cellular vesicles (EVs) are bilayer membrane structures enriched with proteins, nucleic acids and other active molecules and have been implicated in many physiological and pathological processes over the past decade. Recently, evidence suggests EVs to play a more dichotomic role in the regulation of the immune system, whereby an immune response may be enhanced or supressed by EVs depending on their cell of origin and its functional state. EVs derived from antigen (Ag)-presenting cells for instance, have been involved in both innate and acquired (or adaptive) immune responses, as Ag carriers or presenters, or as vehicles for delivering active signalling molecules. On the other hand, tumor and stem cell derived EVs have been identified to exert an inhibitory effect on immune responses by carrying immuno-modulatory effectors, such as transcriptional factors, non-coding RNA (Species) and cytokines. In addition, stem cell-derived EVs have also been reported to impair dendritic cell maturation and to regulate the activation, differentiation and proliferation of B cells. They have been shown to control natural killer cell activity and to suppress the innate immune response. Studies reporting the role of EVs on T lymphocyte modulation are controversial. Discrepancy in literature may be due to stem cell culture conditions, methods of EV purification, EV molecular content and functional state of both parental and target cells. However, mesenchymal stem cell-derived EVs were shown to play a more suppressive role by shifting T cells from an activated to a T regulatory phenotype. In this review we will discuss how stem cell-derived EVs may contribute towards the modulation of the immune response. Collectively, stem cell-derived EVs mainly exhibit an inhibitory effect on the immune system