Extracellular vesicle-derived miR-26b-5p is up-regulated in the serum of patients with diabetic retinopathy

Advances in Extracellular-Vesicles-Based Diagnostic and Therapeutic Approaches for Ocular Diseases

Extracellular vesicles (EVs) are nanoscale membrane vesicles of various sizes that can be secreted by most cells. EVs contain a diverse array of cargo, including RNAs, lipids, proteins, and other molecules with functions of intercellular communication, immune modulation, and regulation of physiological and pathological processes. The biofluids in the eye, including tears, aqueous humor, and vitreous humor, are important sources for EV-based diagnosis of ocular disease. Because the molecular cargos may reflect the biology of their parental cells, EVs in these biofluids, as well as in the blood, have been recognized as promising candidates as biomarkers for early diagnosis of ocular disease. Moreover, EVs have also been used as therapeutics and targeted drug delivery nanocarriers in many ocular disorders because of their low immunogenicity and superior biocompatibility in nature. In this review, we provide an overview of the recent advances in the field of EV-based studies on the diagnosis and therapeutics of ocular disease. We summarized the origins of EVs applied in ocular disease, assessed different methods for EV isolation from ocular biofluid samples, highlighted bioengineering strategies of EVs as drug delivery systems, introduced the latest applications in the diagnosis and treatment of ocular disease, and presented their potential in the current clinical trials. Finally, we briefly discussed the challenges of EV-based studies in ocular disease and some issues of concern for better focusing on clinical translational studies of EVs in the future.

Extracellular vesicles in degenerative retinal diseases: A new therapeutic paradigm

Nanoscale extracellular vesicles (EVs), consisting of exomers, exosomes and microvesicles/ectosomes, have been extensively investigated in the last 20 years, although their biological role is still something of a mystery. EVs are involved in the transfer of lipids, nucleic acids and proteins from donor to recipient cells or distant organs as well as regulating cell-cell communication and signaling. Thus, EVs are important in intercellular communication and this is not limited to sister cells, but may also mediate the crosstalk between different cell types even over long distances. EVs play crucial functions in both cellular homeostasis and the pathogenesis of diseases, and since their contents reflect the status of the donor cell, they represent an additional valuable source of information for characterizing complex biological processes. Recent advances in isolation and analytical methods have led to substantial improvements in both characterizing and engineering EVs, leading to their use either as novel biomarkers for disease diagnosis/prognosis or even as novel therapies. Due to their capacity to carry biomolecules, various EV-based therapeutic applications have been devised for several pathological conditions, including eye diseases. In the eye, EVs have been detected in the retina, aqueous humor, vitreous body and also in tears. Experiences with other forms of intraocular drug applications have opened new ways to use EVs in the treatment of retinal diseases. We here provide a comprehensive summary of the main in vitro, in vivo, and ex vivo literature-based studies on EVs' role in ocular physiological and pathological conditions. We have focused on age-related macular degeneration, diabetic retinopathy, glaucoma, which are common eye diseases leading to permanent blindness, if not treated properly. In addition, the putative use of EVs in retinitis pigmentosa and other retinopathies is discussed. Finally, we have reviewed the potential of EVs as therapeutic tools and/or biomarkers in the above-mentioned retinal disorders. Evidence emerging from experimental disease models and human material strongly suggests future diagnostic and/or therapeutic exploitation of these biological agents in various ocular disorders with a good possibility to improve the patient's quality of life.

Phenotypic Frailty Assessment in SAMP8 Mice: Sex Differences and Potential Role of miRNAs as Peripheral Biomarkers

Frailty is a geriatric syndrome characterized by age-related decline in physiological reserves and functions in multiple organ systems, including the musculoskeletal, neuroendocrine/metabolic, and immune systems. Animal models are essential to study the biological basis of aging and potential ways to delay the onset of age-related phenotypes. Unfortunately, validated animal models of frailty are still lacking in preclinical research. The senescence-accelerated prone-8 (SAMP8) mouse strain exhibits early cognitive loss that mimics the deterioration of learning and memory in the elderly and is widely used as a model of aging and neurodegenerative diseases. Here, we examined the frailty phenotype, which includes body weight, strength, endurance, activity, and slow walking speed, in male and female SAMP8 and senescence-accelerated mouse resistant (SAMR1) mice at 6- and 9-months of age. We found that the prevalence of frailty was higher in SAMP8 mice compared with SAMR1 mice, regardless of sex. The overall percentage of prefrail and frail mice was similar in male and female SAMP8 mice, although the percentage of frail mice was slightly higher in males than in females. In addition, we found sex- and frailty-specific changes in selected miRNAs blood levels. In particular, the levels of miR-34a-5p and miR-331-3p were higher in both prefrail and frail mice, whereas miR-26b-5p was increased only in frail mice compared with robust mice. Finally, levels of miR-331-3p were also increased in whole blood from a small group of frail patients. Overall, these results suggest that SAMP8 mice may be a useful mouse model for identifying potential biomarkers and studying biological mechanisms of frailty.

Extracellular vesicles derived from different sources play various roles in diabetic retinopathy

Extracellular vesicles (EVs) are present in almost all biological fluids and secreted by almost all cell types. A growing number of studies have revealed the potential roles of EVs in the diagnosis and treatment of the diabetic retinopathy (DR). Changes in the quantity and content of EVs may serve as biomarkers of cause or consequence of pathological status of DR, such as inflammation, neovascularization and epithelial-mesenchymal transition. In addition, as natural, safe and efficient drug carrier, EVs have been reported to play important roles in intercellular communication by acting for essential cell-specific information to target cells. In this review, we summarize the roles of EVs, secreted by various types of cells and participated in various biological processes, in the pathogenesis, diagnosis, and treatment of DR.