Rationale: White matter repair is critical for the cognitive and neurological functional recovery after ischemic stroke. M2 microglia are well-documented to enhance remyelination and their extracellular vesicles (EVs) mediate cellular function after brain injury. However, whether M2 microglia-derived EVs could promote white matter repair after cerebral ischemia and its underlying mechanism are largely unknown. Methods: EVs were isolated from IL-4 treated microglia (M2-EVs) and untreated microglia (M0-EVs). Adult ICR mice subjected to 90-minute transient middle cerebral artery occlusion received intravenous EVs treatment for seven consecutive days. Brain atrophy volume, neurobehavioral tests were examined within 28 days following ischemia. Immunohistochemistry, myelin transmission electron microscope and compound action potential measurement were performed to assess white matter structural remodeling, functional repair and oligodendrogenesis. The effects of M2-EVs on oligodendrocyte precursor cells (OPCs) were also examined in vitro . EVs' miRNA sequencing, specific miR-23a-5p knockdown in M2-EVs and luciferase reporter assay were used to explore the underlying mechanism. Results: M2-EVs reduced brain atrophy volume, promoted functional recovery, oligodendrogenesis and white matter repair in vivo , increased OPC proliferation, survival and differentiation in vitro . miR-23a-5p was enriched in M2-EVs and could promote OPC proliferation, survival and maturation, while knocking down miR-23a-5p in M2-EVs reversed the beneficial effects of M2-EVs both in vitro and in vivo . Luciferase reporter assay showed that miR-23a-5p directly targeted Olig3. Conclusion: Our results demonstrated that M2 microglia could communicate to OPCs through M2-EVs and promote white matter repair via miR-23a-5p possibly by directly targeting Olig3 after ischemic stroke, suggesting M2-EVs is a novel and promising therapeutic strategy for white matter repair in stroke and demyelinating disease.

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Exosomes are natural cells-derived vesicles, which are at the forefront toward clinical success for various diseases, including cerebral ischemia. Exosomes mediate cell-to-cell communication in different brain cells during both physiological and pathological conditions. Exosomes are an extensively studied type of extracellular vesicle, which are considered to be the best alternative for stem cell–based therapy. They can be secreted by various cell types and have unique biological properties. Even though native exosomes have potential for ischemic stroke therapy, some undesirable features prevent their success in clinical applications, including a short half-life, poor targeting property, low concentration at the target site, rapid clearance from the lesion region, and inefficient payload. In this review, we highlight exosome trafficking and cellular uptake and survey the latest discoveries in the context of exosome research as the best fit for brain targeting owing to its natural brain-homing abilities. Furthermore, we overview the methods by which researchers have bioengineered exosomes (BioEng-Exo) for stroke therapy. Finally, we summarize studies in which exosomes were bioengineered by a third party for stroke recovery. This review provides up-to-date knowledge about the versatile nature of exosomes with a special focus on BioEng-Exo for ischemic stroke. Standard exosome bioengineering techniques are mandatory for the future and will lead exosomes toward clinical success for stroke therapy.

BackgroundDespite being born with a significant number of primordial cells which representing the ancestor cells of the germ-line, women experience a depletion of ovarian reserve and sub-fertility mid-way into their healthy lives. The poor ovarian response is a substantial limiting factor amplified with higher maternal age and associated with a considerably lower likelihood of pregnancy.MethodsA present analytical prospective cross-sectional study was conducted to explore whether infertile women below the age of 40 years have low ovarian reserve than fertile women of same age, assessed by Antral follicle count (AFC) and anti-Müllerian hormone (AMH), at tertiary care infertility center: Lahore Institute of Fertility and Endocrinology, Hameed Latif Hospital. The study population including 423 infertile and 388 fertile female patients from June 2013 to November 2016. Patients and controls were aged between 25 and 39 years. Serum levels of FSH, LH, AMH were assessed, and AFC was measured by transvaginal sonography on cycle days 2 or 3.ResultsA total of 35.6% of infertile women stated a menstrual cycle length shorter than 21 days, while 21% had a regular cycle length between 24 and 38 days, and 43.2%, longer than 38 days. Overall, the two cohorts did not significantly differ on cycle length. The age-specific reduction of the ovarian reserve was similar in both cohorts; serum AMH concentration decreased by 6% (95% Cl: 5–8%) and AFC decline by 4.5% (95% Cl: 5–7%) per year with increased age. Aged patients (36–39 years) had a 5.3% (95% Cl, 1.5; 7.2) higher risk ratio of having an AMH level < 0.7 ng/ml than women of younger age groups (Kruskal-Wallis test, p < 0.01).ConclusionThis study indicates that the possible common observation of low respondent in ART might not be a result of over-representation of patients with an early age-specific decline in the ovarian reserve, but rather primarily as a consequence of age-specific depletion in the stock of developing follicles at the time of recruitment and selection.