Isolation and characterization of secreted exosomes from adipose tissue- derived mesenchymal stem cells

Background: Mesenchymal stem cells (MSCs) are among the most common types of adult stem cells used in therapeutic medicine having a high rate of differentiation and repair potential. It is known that stem cell derived extracellular vesicles (especially exosomes) have similar functions to their origin cells including providing cell to cell communication which can be used as an appropriate mechanism to the gene or drug delivery in therapeutic medicine. As a result, isolating and characterizing of exosomes could be promising to achieve this goal. In this study we will isolate and characterize the exosomes secreted from adipose tissue derived MSCs (AD-MSCs).Materials and methods: After obtaining adipose samples from patients following liposuction, MSCs were isolated from the adipose tissue using an enzymatic method. Then the isolated cells were cultured in an incubator at 37°C and 5% CO2. After confirming MSCs by flow cytometry of CD90, CD44, CD34 and CD45 markers, the conditioned medium of AD-MSCs at the third passage were used to exosome isolation according to manufacturer’s protocol of exocib kit. The size and morphology of isolated exosomes were assessed using transmission electron microscopy. Additionally, the concentration of exosomes was determined by the Bradford method.Results: After culture and passage of AD-MSCs their conditioned medium at the third passage was collected following 48 hours of culture and exosomes were extracted. The electron microscope showed that the isolated exosomes had a spherical shape with a diameter of 40-150 nm. Also the mean concentration of exosomes was 100 mg/ml.Conclusion: Considering the important role of exosomes in therapeutic medicine the method of isolation and characterization presented in this paper can be an effective and fundamental step for future research studies in the delivery of genes or drugs for treatment purposes.