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.

Epidemiological retrospective analysis in major burn patients: single centre medical records from 2009 to 2019

Burns cause a loss of skin barrier function, rendering it prone to infection. The prevention of infection comprises a focus on the treatment of patients with burns. Therefore, we analysed the results of microbiological tests of patients with severe and extremely severe burns to provide a basis for the prevention and treatment of infection in patients with burns. The results of microbiological tests of patients with severe and extremely severe burns admitted to our burn centre between 2009 and 2019 were retrospectively reviewed. The overall positive rate of microbial detection was 40.67% and did not significantly decline over the 10-year study period. The most common positive sites were wounds, sputum, and urine. The most common bacterial species causing the infections were Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Furthermore, the predictors of a positive detection, overall and at various sites, mainly included the burn area and depth, inhalation injury, and length of the hospital stay. Positive detection was an important predictor of the prognosis. In particular, a positive blood culture and Klebsiella pneumoniae had better predictive strength for mortality than other sites and strains. This study analysed the microbiological testing results at a single burn centre over a period of 10 years. The results provide information regarding the predictors of a positive detection and the influence of a positive detection on prognosis, and can be used as a basis for the development of clinical infection prevention and treatment strategies, as well as the selection of treatment measures.

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 non-volatile 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.