en Clinical Physiology/Pharmacology Clinical Physiology/Pharmacology Experimental research article Experimental research article <span style="font-size:12px;"><span style="font-family:Arial;"><strong>Introduction:</strong> The burn wound healing process is multi-variable, and various factors are involved. Chitosan-based dressings are acceptable materials for wound healing. PProbiotics and postbiotics can in-crease the effectiveness of these dressings. This study aimed to investigate the effect of a biodegradable dressing prepared from chitosan and external microvesicles of Bifidobacterium bifidum on burn wound healing in male Wistar rats.<br /> <strong>Methods:</strong> Bifidobacterium bifidum was cultured, the activated crude supernatant (ACS) was separated, and the microvesicles were isolated with the help of Ultra-centrifugation at 150,000&times;g at 4&deg;C for 30 minutes. Chitosan films containing and without microvesicles were prepared using a heater stirrer at 29&deg;C. The effectiveness of the membranes was evaluated. For this purpose, 60 male rats with second-degree burns were randomly divided into 5 groups (n=12) and were treated for 21 days. The process of wound healing was examined macroscopically and microscopically (wound histology and evaluation of gene expression of cytokines interleukin-8, interleukin-10, and VEGF) on the days 3, 7, 14 and 21. The obtained data were analyzed by IBM SPSS.21 software and using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney tests with p &le; 0.05.<br /> <strong>Results:</strong> The average diameter of microvesicles was 174 &plusmn; 52nm. The thickness of the layers was 2mm. The wounds of the group post-biotic and positive control were closed on the 14th day. Collagen production and epithelialization, as well as inflammation control in the treatment groups, were higher than negative control.<br /> <strong>Conclusion: </strong>The use of chitosan membranes, particularly those enhanced with ACS and microvesicles, represents a significant advancement in wound care by inflammation control, offering a promising strategy for improving the healing of burn wounds.</span></span> Wound healing, Microvesicle, Chitosan, Bifidobacterium bifidum 408 423 http://ppj.phypha.ir/browse.php?a_code=A-10-2456-1&slc_lang=en&sid=1 Seyed Amin Mousavinezhad mousavinezhad101@gmail.com 3200319475328460038647 3200319475328460038647 No Department of Microbiology, Karaj Branch, Islamic Azad University, Karaj, Iran Naser Harzandi nasharzan@gmail.com 3200319475328460038648 0000000327834462 Yes Department of Microbiology, Karaj Branch, Islamic Azad University, Karaj, Iran Azam Marjani marjani.chemistry@gmail.com 3200319475328460038649 3200319475328460038649 No Department of Chemistry, Arak Branch, Islamic Azad University, Arak, Iran Parvaneh Jafari parvaneh.jafari@gmail.com 3200319475328460038650 3200319475328460038650 No Department of Microbiology, Arak Branch, Islamic Azad University, Arak, Iran