Osteoarthritis (OA) is the most orthopedic condition. The pattern of gene expression and the transcription factors that exert control of chondrogenesis have been extensively studied. A systematic search (up to July 2018) of articles assessing the role of microRNA (miRNA) in physiopathology, diagnosis and therapy of OA was performed, with the purpose of giving a critical perspective of the possibilities for diagnostic and therapeutic use of miRNA in the management of OA. miRNAs are small noncoding RNAs that can regulate gene expression in human cells. miRNAs can be expressed in a different fashion in osteoarthritic compared to nonosteoarthritic cartilage. The mechanisms that produce alteration of gene expression in OA are still not completely understood. miRNAs may be involved in the diagnosis of OA as well as in its treatment. There are complex interactions between miRNAs and their multiple target genes. These interactions may be important in gene regulation and the control of homeostatic pathways in OA. miRNA could be useful for diagnostic or management purposes, but the issue of delivery of miRNA targeting agents needs to be overcome before miRNA can be applied in clinical practice.

Introduction: The regulatory role of microRNA (miRNA) in several conditions has been studied, but their function in tendon healing remains elusive. This review summarizes how miRNAs are related to the pathogenesis of tendon injuries and highlights their clinical potential, focusing on the issues related to their delivery for clinical purposes.Sources of data: We searched multiple databases to perform a systematic review on miRNA in relation to tendon injuries. We included in the present work a total of 15 articles.Areas of agreement: The mechanism of repair of tendon injuries is probably mediated by resident tenocytes. These maintain a fine equilibrium between anabolic and catabolic events of the extracellular matrix. Specific miRNAs regulate cytokine expression and orchestrate proliferation and differentiation of stromal cell lines involved in the composition of the extracellular matrix.Areas of controversy: The lack of effective delivery systems poses serious obstacles to the clinical translation of these basic science findings.Growing point: In vivo studies should be planned to better explore the relationship between miRNA and tendon injuries and evaluate the most suitable delivery system for these molecules.Areas timely for developing research: Investigations ex vivo suggest therapeutic opportunities of miRNA for the management of tendon injuries. Given the poor pharmacokinetic properties of miRNAs, these must be delivered by an adequate adjuvant transport system.