Introduction: Wound healing is a sophisticated dynamic process that involves complex coordination among a variety of resident cells in a suitable extracellular environment. Chronic wounds are defined as wounds that fail to heal within a period of 3 months. Negative pressure wound therapy (NPWT) is a closed suction drainage system is used to enable mass transport of fluid from the body as an adjunct to surgical procedures. (Oasis-ultra) is a triple layer extracellular matrix containing different types of glycosaminoglycans (GAGs) like heparin sulfate, hyaluronic acid and chondroitin sulfate. In addition, it has adhesion molecule such as fibronectin and laminin along with various growth factors. Extracellular vesicles, (EVs); microvesicles and exosomes are a diverse family of membrane bound vesicles laden with various proteins, nucleic acids, and lipids that cells release to the extracellular environment. EVs play a crucial role in cell to cell communication, as they carry signaling molecules, like lipids, proteins, mRNAs, and miRNAs. We hypothesize that there is a correlation between the concentration of EMVs and the percentage of wound healing in treated chronic wounds and the healing percentage will be enhanced by the combination of Oasis ultra and NPWT. A prospective, multi-centered, randomized, single-blinded clinical trial that permitted by the Ethics Committee of the Copernicus was conducted to study whether the combination of Oasis ultra and NPWT will enhance the healing of chronic wounds when compared with only NPWT, to measure the concentration of EMVs in the collected wound fluids and correlate it with the percentage of wound healing and to analyze the extracellular microvesicles composition to look for growth factors, chemokines and cytokines that play role in the wound healing
Material and Methods: Wound fluid samples obtained from 14 patients with stage IV trunk pressure ulcers. The patients were divided in two groups (7 in each group, n=7): control group on negative pressure wound therapy (NPWT) alone & study group with NPWT plus Oasis Ultra dressing. NPWT was replaced two times a week, and Oasis Ultra was applied once weekly for all subjects. Wound size was measured every week and healing percentage was calculated for the whole 12 weeks of the study. A canister of NPWT device (wound VAC) was collected from the patients every four weeks of the study and brought to the lab where a hole was made in the canister by using a drill to drain the fluids. Protease inhibitor added to the fluid before the fluid stored in a -80°C freezer. EMVs were isolated using Differential Ultracentrifugation methods, and EMVs concentration in wound fluid was measured by Nanoparticle Tracking Analysis machine (Nanosight). EMVs were analyzed for cytokines and growth factors using BioPlex Pro cytokine assays after determining protein concentration using Bradford assay.
Results: Our data showed that overall healing percentage in the study group after 12 weeks of study was ~ 89% as compared with the control group, which was ~ 52% (P < 0.05). Further, to examine the correlation between EMVs and wound healing percentage, simple linear regression was conducted using SPSS and Prism pad soft wares. The data showed that there is a strong positive correlation between EMVs concentrations in wound fluid and the healing percentage, the R-square was 0.66, and (P = 0.05). The study group shows high levels of intravesicular concentration of pro-healing cytokines and low levels pro-inflammatory cytokines; however, control group shows high levels of intravesicular concentration of pro-inflammatory cytokines and low levels of pro-healing cytokine
Conclusion: Our clinical trial demonstrates that using Oasis-Ultra combined with NPWT hasten the healing percentage in stage IV pressure ulcers. There is a correlation between EMVs concentration in wound fluid and the healing percentage of the wound. EMVs composition could determine the outcomes of the wound healing. The EMVs particles in wound fluid could serve as a biomarker of the wound healing.