en Pharmacokinetics/Dynamics Pharmacokinetics/Dynamics Experimental research article Experimental research article <div style="text-align: justify;"><strong>Introduction: </strong>Wound healing is one of the most critical issues human has been faced since the beginning of creation. Biodegradable polymers are of particular importance. In this study, cell-free supernatant (CFS) of Bifidobacterium bifidum combined with chitosan (CH) film was evaluated as a wound dressing. <strong>Methods:</strong> Biodegradable films (CH and CFS/CH), as a novel wound dressing, were prepared. For the evaluation of dressing efficacy, 45 male Wistar rats weighing 200-250 g were randomly divided into 3 groups: negative control (without wound treatment), positive control (wound treatment by CH film), and probiotic (wound treatment by CFS/CH film). One full thickness wound was created on the dorsal area of the animals. The wound in positive control and probiotic groups were immediately covered by CH and CFS/CH dressing, respectively. Wound healing process was evaluated by macroscopic observation and histological analysis. During the treatment the expression of IL-1, TGF-B and IL-6 were assayed by qRT-PCR. <strong>Results:</strong> Our results showed different infiltration patterns of macrophages, fibroblasts, and neutrophils in CFS/CH treated group. Enhanced disposition of collagen and elastin caused improvement of wound healing process by the film. Based on the gene expression results, use of CFS/CH film caused improvement in wound healing kinetic. <strong>Conclusion:</strong> The biodegradable film based on chitosan and CFS of B. bifidum improves the wound healing process.</div> Wound healing, Chitosan, Cell free supernatant, Biodegradable-film, Cytokines 468 479 http://ppj.phypha.ir/browse.php?a_code=A-10-1421-2&slc_lang=en&sid=1 Atena Bazjou 3200319475328460031607 3200319475328460031607 No Department of Microbiology, Arak Branch, Islamic Azad University, Arak, Iran Parvaneh Jafari p-jafari@iau-arak.ac.ir 3200319475328460031608 3200319475328460031608 Yes Department of Microbiology, Arak Branch, Islamic Azad University, Arak, Iran Azam Marjani 3200319475328460031609 3200319475328460031609 No Department of Chemistry, Arak Branch, Islamic Azad University, Arak, Iran Neda Akbari 3200319475328460031610 3200319475328460031610 No Department of Microbiology, Arak Branch, Islamic Azad University, Arak, Iran