Proficiency of Carboxymethyl cellulose as a Cryoprotectant. Clinical and Histological Evaluation of Cryopreserved Heterogenous Mesenchymal Stem Cell-Exosomal Hydrogel on Critical Size Skin Wounds in Dogs

Abstract

Background: Fresh stem cell exosomes are usually obtained and reused in the same individual. It cannot be kept viable for a long period of time regardless of the lengthy preparation time. Freezing is typically used to preserve the viability of perishable materials and increase their lifetime. Regrettably, normal freezing of biomaterials leads to cell damage. Therefore, a cryoprotectant can save the cells from the conventional cryodamage. Sodium carboxymethylcellulose (NA-CMC) is a powdery substance that is used to manufacture bio-safe hydrofilm gels because of its high viscosity, cytocompatibility, and nonallergenic nature.
 Materials and Methods: Sterile CMC hydrogel was prepared, part of which was loaded with exosomal solution derived from MSCs. The gel was kept at −20°C for preservation. Two bilateral full-thickness circular skin wounds of 2-cm diameter were created on the back of experimental dogs. The wounds were at least 2.5 cm apart. Treatment started 24 hours after wound creation. Group I received CMC gel solely, whereas group II received frozen CMC exosomal gel. The gel was applied 4 times, a single application per day with 1- day interval.
 Results: Clinically, the frozen exosomal gel significantly promoted wound healing with no scaring. Histologically, enhanced dermal fibroblasts and organized collagen deposition were seen in the treated group.
 Conclusion: CMC proved to be an efficient cryoprotectant and a suitable vehicle for exosomes. Deep freezing was proven to conserve the viability, extended the preservation, and facilitated the usage of exosomal gel. This technique of preserved cell-free therapy is inexpensive, time-saving, and proficient and seems suitable for treating cutaneous wounds.

Evaluation of the Efficacy of Microvesicles Derived from Mesenchymal Stem Cells on ‎Healing of Experimentally Induced Full-Thickness Skin Wound in Donkeys

“…In contrary, the saline treated wounds showed high proliferation of fibrous tissue with very high congestion and hemorrhage at 21 days and showed mature fibrous tissue with hemorrhagic granulation tissue at 42 days post wounding. These findings are similar to that reported by El-Tookhy et al (2017) and Bahr et al (2021).…”

“…Wounds treated with MVs showed faster wound contraction than observed in the control group and the percentage of wound contraction was significantly higher in MVs group than the control group from 7 days post wounding till the end of the observation period. Similar results reported by El-Tookhy et al (2017) and Bahr et al, (2021).…”

“…It was suggested that at least 1×106 cells/cm2 of wound should be used for a significant therapeutic effect (Falanga et al, 2007). In the present study, the amount of microvesicle solution used equal to the amount obtained from 2×106 MSCs/wound similar to (Fu et al, 2006;Basiouny et al, 2013;Abd-Allah et al, 2015). The route of administration also varied.…”

“…The route of administration also varied. Some studies demonstrate that the treatment could be achieved by intra-dermal injection (Kim et al, 2013;Abd-Allah et al, 2015), local and systemic injection (Tark et al, 2010;Basiouny et al, 2013), or spray (Falanga et al, 2007). In this study, the MVs solution was subcutaneously and intradermally injected around each wound similar to (El-Tookhy et al, 2017; Chen et al, 2008).Moreover, in this study, the MVs solution was injected two times with oneweek interval starting 24hr after wound creation in contrary to the study reported by El-Tookhy et al (2017) in which the solution is used as a single injection 24 hrs after wound creation.…”

“…MVs are membrane vesicles that are released by many types of cells and have recently been considered important mediators of cell-to-cell communication. It serves as a vehicle to transfer proteins and messenger RNA and microRNA (miRNA) to distant cells, which alters the gene expression, proliferation, and differentiation of the recipient cells (Chen & Chen, 2015).However, several studies described the effect of mesenchymal stem cells derived microvesicles on wound healing in dogs (El-Tookhy et al, 2017;Bahr et al, 2021) and in mice (Trinh et al, 2016;Ren et al, 2019). There was little information in the literature about the use of mesenchymal stem cells derived microvesicles in management of wounds in equine.…”