Thesis (M.Sc.) - Cairo University - Faculty of Veterinary Medicine - Department of Surgery Anesthesiology and Radiology

Extracellular vesicles are nanosized vesicles released by different cells and have been separated from most of the body fluids.These vesicles play acentral role in cell to cell communication. They serve in regulating normal physiological processes.EVs released from stem cells exert similar therapeutic effect to their originating cells.Fresh stem cells exosomes are usually obtained and re-used in the same individual. Regardless the lengthy preparation time, it cannot be kept viable for long periods of time. So Clinical application of EVs requires the preparation of sufficient and viable active therapeutic-EVs as well as implementing suitable methods for long term preservation to expedite both their clinical and commercial uses.This study defined some methods may be suitable for preservation of therapeutic-EVsas Cryopreservation and drying method (freeze drying & spray drying), discuss the obstacles associated with preservation methods and evaluate the efficacy of cryopreservedEVsusing Sodium carboxy-methylcellulose (NA-CMC) as cryoprotectantin treatment skin woundclinically, Histologically and immunohistochemically.SterileCMC hydrogel was prepared, part of which was loaded with exosomal solution derived from MSCs.The gel was kept at -20{u00B0}C for preservation.Two bilateral full-thickness circular skin wounds of 2 cm diameter were created on the back of threeexperimental dogs. The wounds were at least 2.5 cm apart.Twenty-four hours after wound creation, treatment started. Group I received CMC gel solely; Group II received frozen CMC exosomal gel. The gel wasapplied 4 times, single application/day, one day interval.the frozen exosomal gel significantly promoted wound healing with no scaring, dermal fibroblasts were enhanced, and organized collagen deposition were seen in the treated group

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