microRNAs (miRNAs) are small non-coding RNAs required for the post-transcriptional control of gene expression. MicroRNAs play a critical role in modulating muscle regeneration and stem cell behavior. Muscle regeneration is affected in muscular dystrophies, and a critical point for the development of effective strategies for treating muscle disorders is optimizing approaches to target muscle stem cells in order to increase the ability to regenerate lost tissue. Within this framework, miRNAs are emerging as implicated in muscle stem cell response in neuromuscular disorders and new methodologies to regulate the expression of key microRNAs are coming up. In this review, we summarize recent advances highlighting the potential of miRNAs to be used in conjunction with gene replacement therapies, in order to improve muscle regeneration in the context of Duchenne Muscular Dystrophy (DMD).

The epicardium is the outermost cell layer in the vertebrate heart that originates during development from mesothelial precursors located in the proepicardium and septum transversum. The epicardial layer plays a key role during cardiogenesis since a subset of epicardial-derived cells (EPDCs) undergo an epithelial–mesenchymal transition (EMT); migrate into the myocardium; and differentiate into distinct cell types, such as coronary vascular smooth muscle cells, cardiac fibroblasts, endothelial cells, and presumably a subpopulation of cardiomyocytes, thus contributing to complete heart formation. Furthermore, the epicardium is a source of paracrine factors that support cardiac growth at the last stages of cardiogenesis. Although several lineage trace studies have provided some evidence about epicardial cell fate determination, the molecular mechanisms underlying epicardial cell heterogeneity remain not fully understood. Interestingly, seminal works during the last decade have pointed out that the adult epicardium is reactivated after heart damage, re-expressing some embryonic genes and contributing to cardiac remodeling. Therefore, the epicardium has been proposed as a potential target in the treatment of cardiovascular disease. In this review, we summarize the previous knowledge regarding the regulation of epicardial cell contribution during development and the control of epicardial reactivation in cardiac repair after damage.

The outermost layer of the heart, the epicardium, is an essential cell population that contributes, through epithelial-to-mesenchymal transition (EMT), to the formation of different cell types and provides paracrine signals to the developing heart. Despite its quiescent state during adulthood, the adult epicardium reactivates and recapitulates many aspects of embryonic cardiogenesis in response to cardiac injury, thereby supporting cardiac tissue remodeling. Thus, the epicardium has been considered a crucial source of cell progenitors that offers an important contribution to cardiac development and injured hearts. Although several studies have provided evidence regarding cell fate determination in the epicardium, to date, it is unclear whether epicardium-derived cells (EPDCs) come from specific, and predetermined, epicardial cell subpopulations or if they are derived from a common progenitor. In recent years, different approaches have been used to study cell heterogeneity within the epicardial layer using different experimental models. However, the data generated are still insufficient with respect to revealing the complexity of this epithelial layer. In this review, we summarize the previous works documenting the cellular composition, molecular signatures, and diversity within the developing and adult epicardium.

The outermost layer of the heart, the epicardium, is an essential cell population that contributes, through epithelial-to-mesenchymal transition (EMT), to form different cell types and provide paracrine signals to the developing heart. Despite its quiescent state during adulthood, in response to cardiac injury, adult epicardium reactivates and recapitulates many aspects of embryonic cardiogenesis supporting cardiac tissue remodeling. Thus, the epicardium has been considered as a crucial source of cell progenitors with important contribution to developing and injured heart. Although several studies have provided evidence about cell fate determination in the epicardium, to date it is unclear whether epicardial-derived cells (EPDCs) come from specific, and previously predetermined, epicardial cell subpopulations or if they are derived from a common progenitor. In recent years, different approaches have been used to study cell heterogeneity within the epicardial layer by using different experimental models. However, generated data are still insufficient to understand the complexity of this epithelial layer. In this review, we summarize the previous works supporting the cellular composition, molecular signatures and diversity within the developing and adult epicardium.

Skeletal muscle represents between 30 and 38% of the human body mass. Both the maintenance and repair of adult muscle tissue are directed by satellite cells (SCs). SCs are located beneath the basal lamina of the skeletal muscle myofiber. They are quiescent for most of their life but, in response to physiological stimuli or muscle trauma, they activate, proliferate, and enter the myogenic program via generating myogenic progenitors (myoblasts) that fuse to existing myofibers or de novo myofibers. MicroRNAs (miRNAs or miRs) play a critical role in regulating muscle regeneration and stem cell behavior. In this chapter, we review the pivotal role in the regulation of SC quiescence, activation, and differentiation in the context of muscular dystrophies.