Recombinant Human Collagen Type III Improves Hypertrophic Scarring by Regulating the Ratio of Type I/III Collagen.

Hypertrophic scar development is a complication associated with wound healing, impacting local appearance and function. The type I/III collagen ratio affects the extent of hypertrophic scarring; a reduced ratio can ameliorate this. In this study, recombinant human collagen type III was developed. Liquid chromatography-tandem mass spectrometry was used to determine its amino acid sequence and confirm its high level of homology with natural human type III collagen. Recombinant human collagen type III displayed no cytotoxicity and did not confer skin irritation and sensitization. Immunofluorescence and western blot analyses of histidine following incubation with fibroblasts suggested cell entry of recombinant human collagen type III. Furthermore, recombinant human collagen type III promoted the synthesis of the natural type III collagen in fibroblasts, resulting in a more obvious increase of type III collagen content in fibroblasts than that of type I collagen, and then decreased the ratio of type I/III collagen. The results of 5-ethynyl-2'-deoxyuridine staining assay suggested enhanced fibroblast proliferation. Following local injection of recombinant human collagen type III, rabbit ear scarring was significantly reduced after 60 days. Vancouver Scar Scale evaluation showed that all index scores were significantly reduced. Western blotting and Picro-Sirius red staining showed that the natural type III collagen increase in scar tissue was greater than that of type I collagen, decreasing the type I/III ratio. In summary, recombinant human collagen type III can be taken up by fibroblasts and promote natural collagen synthesis-especially that of type III-thereby reducing the type I/III ratio and improving hypertrophic scarring.

Characterization of Bacterial Community Structure Dynamics in a Rat Burn Wound Model Using 16S rRNA Gene Sequencing.

Burns destroy the skin barrier and alter the resident bacterial community, thereby facilitating bacterial infection. To treat a wound infection, it is necessary to understand the changes in the wound bacterial community structure. However, traditional bacterial cultures allow the identification of only readily growing or purposely cultured bacterial species and lack the capacity to detect changes in the bacterial community. In this study, 16S rRNA gene sequencing was used to detect alterations in the bacterial community structure in deep partial-thickness burn wounds on the back of Sprague-Dawley rats. These results were then compared with those obtained from the bacterial culture. Bacterial samples were collected prior to wounding and 1, 7, 14, and 21 days after wounding. The 16S rRNA gene sequence analysis showed that the number of resident bacterial species decreased after the burn. Both resident bacterial richness and diversity, which were significantly reduced after the burn, recovered following wound healing. The dominant resident strains also changed, but the inhibition of bacterial community structure was in a nonvolatile equilibrium state, even in the early stage after healing. Furthermore, the correlation between wound and environmental bacteria increased with the occurrence of burns. Hence, the 16S rRNA gene sequence analysis reflected the bacterial condition of the wounds better than the bacterial culture. 16S rRNA sequencing in the Sprague-Dawley rat burn model can provide more information for the prevention and treatment of burn infections in clinical settings and promote further development in this field.

Effects of depression on healing and inflammatory responses of acute wounds in rats.

This study aimed to elucidate the effect of depression on the healing of acute wounds in rats. We hypothesized that depression would have negative effects on inflammation and wound healing and that antidepressant therapy would reverse these effects. This study included 100 rats randomly allocated into five groups: control group (CG), depression group (DG), pre-depression group (PDG), antidepressant group (AG), and pre-antidepressant group (PAG). Acute wounds were created on the rats' backs. The groups were subjected to no interventions (CG), aversive stimuli before (PDG) and after (DG) wound creation, and antidepressant treatment before (PAG) and after (AG) wound creation. On the day of wound creation and on days 3, 6, 9, and 12 after wound creation, observations of the wound area and degree of depression (evaluated using the sucrose preference test, open-field test, and weight change) were recorded. On days 6 and 12 after wound creation, venous serum and wound tissues were collected. Tumor necrosis factor alpha (TNF-α), interleukin (IL)-1ß, IL-6, and IL-10 levels were measured using the enzyme-linked immunosorbent assay. Results showed an initial increase followed by a decrease in the degree of depression in all groups except DG (continuous decline). The wound-healing rate was significantly lower in PDG and DG than in CG; it was higher in AG and PAG than in CG. DG and PDG had higher concentrations of inflammatory cytokines than CG, and AG and PAG had lower concentrations than CG. This indicates that the onset of depression delays the healing of acute wounds and aggravates the inflammatory response in rats. Antidepressant treatment counteracts both of these negative effects.