Numerous challenges remain within conventional cell-based therapy despite the growing trend of stem cells used to treat various life-debilitating diseases. These limitations include batch-to-batch heterogeneity, induced alloreactivity, cell survival and integration, poor scalability, and high cost of treatment, thus hindering successful translation from lab to bedside. However, recent pioneering technology has enabled the isolation and enrichment of small extracellular vesicles (EVs), canonically known as exosomes. EVs are described as a membrane-enclosed cargo of functional biomolecules not limited to lipids, nucleic acid, and proteins. Interestingly, studies have correlated the biological role of MSC-EVs to the paracrine activity of MSCs. This key evidence has led to rigorous studies on MSC-EVs as an acellular alternative. Using EVs as a therapy was proposed as a model leading to improvements through increased safety; enhanced bioavailability due to size and permeability; reduced heterogeneity by selective and quantifiable properties; and prolonged shelf-life via long-term freezing or lyophilization. Yet, the identity and potency of EVs are still relatively unknown due to various methods of preparation and to qualify the final product. This is reflected by the absence of regulatory strategies overseeing manufacturing, quality control, clinical implementation, and product registration. In this review, the authors review the various production processes and the proteomic profile of MSC-EVs.

Background/Objective: Metabolic syndrome (MetS) is characterized by abdominal obesity, increased blood pressure (BP), fasting blood glucose (FBG) and triglyceride levels, and reduced high-density lipoprotein (HDL) levels. This study aims to investigate the efficacy of the Wharton’s jelly mesenchymal stem cells (WJMSCs)-derived small extracellular vesicles’ (sEVs) preparations in managing MetS. Method: Twenty-four rats were fed with a high-fat and high-fructose diet to induce MetS for 16 weeks and randomized into three groups (n = 8/group): a MetS Control group treated with normal saline, MetS Low Dose (LD) group treated with a LD of sEVs preparations (3 × 10⁹ particle/rat), and MetS High Dose (HD) group treated with a HD of sEVs preparations (9 × 10⁹ particles/rat). The Control Non-Disease (ND) group was given a standard rat diet and autoclaved tap water with normal saline as treatment. Treatments were given via intravenous injection every three weeks for twelve weeks. Rats were assessed every six weeks for physical measurements, FBG, lipid profiles, CRP, leptin, adiponectin, and BP. Necropsy evaluation was performed on the lungs, liver, spleen, and kidney. Results: Significant reductions in FBG, triglycerides, BP, and increased HDL levels were observed in the treated groups compared to the control group. However, significant abdominal circumference (AC) improvement was not observed in the treated groups. Non-significant associations were found between fasting CRP, leptin, and adiponectin levels with MetS rats after treatment. In addition, sEVs preparations improved inflammation and hemorrhage in the lung and mineralisation in the renal of the treated group. Conclusions: Human fetal WJMSCs-derived sEVs preparations improve all the clusters of MetS in rats except AC and could be further explored as a treatment for MetS.

Umbilical cord mesenchymal stem cells (UCMSCs)-derived small extracellular vehicles (sEVs) are reported to offer therapeutic effects in regenerative medicine, but they lack safety and biodistribution profiles to support smooth translation at the clinical stage and regulatory requirements. Our study aimed to determine the safety and biodistribution profile in a healthy animal model before application in the metabolic syndrome model. Method: Healthy male Sprague Dawley (SD) rats were given an intravenous (IV) injection of normal saline (control group) or pooled fetal UCMSCs-derived sEVs (treated group) every three weeks for 90 days. Morbidity and mortality observation (daily), physical measurements (weekly), selected serum biochemistry (every three weeks), and hematology (every three weeks) were performed for 90 days. Acute toxicity (on day 14) and sub-chronic toxicity (on day 90) were assessed for gross necropsy, relative organ weight, and histopathological assessment of lungs, liver, spleen, kidney, and lymph nodes. Separately, a biodistribution study was conducted with the sEVs preparations labeled with PKH26 fluorescent dye, given intravenously to the rats. The organs were harvested 24 h post-injection. There were no drastic changes in either group’s morbidity or mortality, physical, hematological, and biochemistry evaluation. The histopathological assessment concluded moderate (focal) inflammation in the treated group’s kidneys and signs of recovery from the inflammation and vascular congestion in the liver. A biodistribution study revealed a higher accumulation of sEVs in the spleen. Multiple IV injections of the pooled fetal UCMSCs-derived sEVs in healthy male SD rats were deemed safe. The sEVs were abundantly distributed in the spleen 24 h post-injection.