OBJECTIVE: This study tests the efficacy of Bletilla striata polysaccharide (BSP), carboxymethyl chitosan (CMC), baicalin (BA) and silver titanate (ST) in a wound dressings to fight infection, promote healing and provide superior biocompatibility. METHODS: The antibacterial activity of BA and ST was evaluated in vitro using the inhibition zone method. BA/ST/BSP/CMC porous sponge dressings were prepared and characterized. The biocompatibility of BA/ST/BSP/CMC was assessed using the cell counting kit-8 assay. The therapeutic effect of BA/ST/BSP/CMC was further investigated using the dorsal skin burn model in Sprague-Dawley rats. RESULTS: The wound dressing had good antibacterial activity against Escherichia coli and Staphylococcus aureus through BA and ST, while the combination of BSP and CMC played an important role in promoting wound healing. The BA/ST/BSP/CMC porous sponge dressings were prepared using a freeze-drying method with the concentrations of BA and ST at 20 and 0.83 mg/mL, respectively, and the optimal ratio of 5% BSP to 4% CMC was 1:3. The average porosity, water absorption and air permeability of BA/ST/BSP/CMC porous sponge dressings were measured to be 90.43%, 746.1% and 66.60%, respectively. After treatment for 3 and 7 days, the healing rates of the BA/ST/BSP/CMC group and BA/BSP/CMC group were significantly higher than those of the normal saline (NS) group and silver sulfadiazine (SSD) group (P < 0.05). Interleukin-1β expression in the BA/ST/BSP/CMC group at 1 and 3 days was significantly lower than that in the other three groups (P < 0.05). After being treated for 3 days, vascular endothelial growth factor expression in the BA/BSP/CMC group and BA/ST/BSP/CMC group was significantly higher than that in the NS group and SSD group (P < 0.05). Inspection of histological sections showed that the BA/ST/BSP/CMC group and BA/BSP/CMC group began to develop scabbing and peeling of damaged skin after 3 days of treatment, indicating accelerated healing relative to the NS group and SSD group. CONCLUSION The optimized concentration of BA/ST/BSP/CMC dressing was as follows: 6 mg BSP, 14.4 mg CMC, 0.5 mg ST and 12 mg BA. The BA/ST/BSP/CMC dressing, containing antibacterial constituents, was non-cytotoxic and effective in accelerating the healing of burn wounds, making it a promising candidate for wound healing. Please cite this article as: Gong YR, Zhang C, Xiang X, Wang ZB, Wang YQ, Su YH, Zhang HQ. Baicalin, silver titanate, Bletilla striata polysaccharide and carboxymethyl chitosan in a porous sponge dressing for burn wound healing. J Integr Med. 2023; 21(5): 487-495.
Rats ; Animals ; Chitosan/pharmacology* ; Silver/pharmacology* ; Porosity ; Vascular Endothelial Growth Factor A/pharmacology* ; Rats, Sprague-Dawley ; Wound Healing ; Polysaccharides/pharmacology* ; Bandages ; Burns/drug therapy* ; Anti-Bacterial Agents/pharmacology* ; Silver Sulfadiazine/pharmacology*

Objective: To explore the effects and mechanism of water-soluble chitosan hydrogel on infected full-thickness skin defect wounds in diabetic mice. Methods: The experimental research method was adopted. The control hydrogel composed of polyvinyl alcohol and gelatin, and the water-soluble chitosan hydrogel composed of the aforementioned two materials and water-soluble chitosan were prepared by the cyclic freeze-thaw method. The fluidity of the two dressings in test tube before and after the first freeze-thawing was generally observed, and the difference in appearance of the final state of two dressings in 12-well plates were compared. According to random number table (the same grouping method below), the cell strains of L929 and HaCaT were both divided into water-soluble chitosan hydrogel group and control hydrogel group, respectively. After adding corresponding dressings and culturing for 24 h, the cell proliferation activity was measured using cell counting kit 8. Rabbit blood erythrocyte suspensions were divided into normal saline group, polyethylene glycol octyl phenyl ether (Triton X-100) group, water-soluble chitosan hydrogel group, and control hydrogel group, which were treated accordingly and incubated for 1 hour, and then the hemolysis degree of erythrocyte was detected by a microplate reader. Twenty-four female db/db mice aged 11-14 weeks were selected, and full-thickness skin defect wounds on their backs were inflicted and inoculated with the methicillin-resistant Staphylococcus aureus (MRSA), 72 h later, the mice were divided into blank control group, sulfadiazine silver hydrogel group, control hydrogel group, and water-soluble chitosan hydrogel group, which were treated accordingly. On post injury day (PID) 0 (immediately), 7, 14, and 21, the healing of the wound was observed. On PID 14 and 21, the wound healing rate was calculated. On PID 14, MRSA concentration in wounds was determined. On PID 21, the wounds were histologically analyzed by hematoxylin and eosin staining; the expression of CD31 in the wounds was detected by immunofluorescence method, and its positive percentage was calculated. Raw264.7 cells were taken and divided into interleukin-4 (IL-4) group, blank control group, control hydrogel group, and water-soluble chitosan hydrogel group, which were treated accordingly. At 48 h of culture, the percentages of CD206 positive cells were detected by flow cytometry. The number of samples was all 3. Data were statistically analyzed with independent sample t test, one-way analysis of variance, analysis of variance for repeated measurement, least significant difference test, and Dunnett T3 test. Results: Two dressings in test tube had certain fluidity before freeze-thawing and formed semi-solid gels after freeze-thawing for once. The final forms of two dressings in 12-well plates were basically stable and translucent sheets, with little difference in transparency. At 24 h of culture, the cell proliferation activities of L929 and HaCaT in water-soluble chitosan hydrogel group were significantly higher than those in control hydrogel group (with t values of 6.37 and 7.50, respectively, P<0.01). At 1 h of incubation, the hemolysis degree of erythrocyte in water-soluble chitosan hydrogel group was significantly lower than that in Triton X-100 group (P<0.01), but similar to that in normal saline group and control hydrogel group (P>0.05). On PID 0, the traumatic conditions of mice in the 4 groups were similar. On PID 7, more yellowish exudates were observed inside the wound in blank control group and control hydrogel group, while a small amount of exudates were observed in the wound in sulfadiazine silver hydrogel group and water-soluble chitosan hydrogel group. On PID 14, the wounds in blank control group and control hydrogel group were dry and crusted without obvious epithelial coverage; in sulfadiazine silver hydrogel group, the scabs fell off and purulent exudate was visible on the wound; in water-soluble chitosan hydrogel group, the base of wound was light red and obvious epithelial coverage could be observed on the wound. On PID 14, the wound healing rate in water-soluble chitosan hydrogel group was significantly higher than that in the other 3 groups (all P<0.01). On PID 21, the wound in water-soluble chitosan hydrogel group was completely closed, while the wounds in the other 3 groups were not completely healed; the wound healing rate in water-soluble chitosan hydrogel group was significantly higher than that in the other 3 groups (all P<0.01). On PID 14, the concentration of MRSA in the wound in water-soluble chitosan hydrogel group was significantly lower than that in blank control group (P<0.01), but similar to that in control hydrogel group and sulfadiazine silver hydrogel group (P>0.05). On PID 21, the new epidermis was severely damaged in blank control group; the epidermis on the wound in control hydrogel group also had a large area of defect; complete new epidermis had not yet being formed on the wound in sulfadiazine silver hydrogel group; the wound in water-soluble chitosan hydrogel group was not only completely covered by the new epidermis, the basal cells of the new epidermis were also regularly aligned. On PID 21, the percentage of CD31 positivity in the wound in water-soluble chitosan hydrogel group was (2.19±0.35)%, which was significantly higher than (0.18±0.05)% in blank control group, (0.23±0.06)% in control hydrogel group, and (0.62±0.25)% in sulfadiazine silver hydrogel group, all P<0.01. At 48 h of culture, the percentage of CD206 positive Raw264.7 cells in water-soluble chitosan hydrogel group was lower than that in IL-4 group (P>0.01) but significantly higher than that in blank control group and control hydrogel group (P<0.05 or P<0.01). Conclusions: The water-soluble chitosan hydrogel has good biosafety and can induce higher level of macrophage M2 polarization than control hydrogel without water-soluble chitosan, so it can enhance the repair effect of MRSA-infected full-thickness skin defect wounds in diabetic mice and promote rapid wound healing.
Mice ; Female ; Animals ; Rabbits ; Interleukin-4 ; Hydrogels/pharmacology* ; Wound Healing ; Chitosan/pharmacology* ; Diabetes Mellitus, Experimental ; Water ; Methicillin-Resistant Staphylococcus aureus ; Gelatin ; Polyvinyl Alcohol ; Hemolysis ; Saline Solution ; Eosine Yellowish-(YS) ; Hematoxylin ; Octoxynol ; Silver ; Phenyl Ethers ; Sulfadiazine

OBJECTIVETo investigate the antibacterial activity of silver sulfadiazine (SD-Ag), mupirocin, and clotrimazole used alone or in combination against methicillin-resistant Staphylococcus aureus (MRSA) isolated from burn wounds.

METHODSEighteen MRSA isolates from wound excretion of 18 burn patients hospitalized in our unit from July to December 2011 were collected continuously and non-repetitively. (1) Minimum inhibitory concentration (MIC), 50% MIC (MIC50), and 90% MIC (MIC90) of SD-Ag, mupirocin, and clotrimazole used alone, those of SD-Ag and mupirocin used in combination, and those of SD-Ag, mupirocin, and clotrimazole used in combination to MRSA were determined by checkerboard agar dilution method. (2) Fractional inhibitory concentration (FIC) index was calculated to determine the combined effect of SD-Ag plus mupirocin, and SD-Ag plus mupirocin and clotrimazole. Synergy with FIC index less than or equal to 0.5 or additivity with FIC index more than 0.5 and less than or equal to 1.0 was regarded as effective, and indifference with FIC index more than 1.0 and less than or equal to 4.0 or antagonism with FIC index more than 4.0 was regarded as ineffective. The effective ratio was compared with overall ratio (assumed as 0) by unilateral binomial distribution test.

RESULTSThe MIC, MIC50, and MIC90 of SD-Ag, mupirocin, and clotrimazole used alone against 18 MRSA isolates were respectively 8, 8, 16 µg/mL; 2, 16, 64 µg/mL; 2, 2, 2 µg/mL. MIC of antimicrobial agents used in combination decreased from 3.1% to 50.0% as compared with that of individual agent used alone. Compared with those of single application of SD-Ag and mupirocin, MIC50 of SD-Ag and that of mupirocin both decreased 75.0%, and MIC90 of them decreased 87.5% when SD-Ag and mupirocin were used in combination. Compared with those of single application of SD-Ag, mupirocin, and clotrimazole, MIC50 of SD-Ag, mupirocin, and clotrimazole respectively decreased 75.0%, 87.5%, and 50.0%; MIC90 of them respectively decreased 87.5%, 96.9%, and 50.0% when SD-Ag, mupirocin, and clotrimazole were used in combination. Among the 18 MRSA isolates, the combined effect of SD-Ag and mupirocin was synergic in 9 isolates, additive in 7 isolates, indifferent in 2 isolates, and antagonistic in 0 isolate; the combined effect of SD-Ag, mupirocin, and clotrimazole was additive in 16 isolates, indifferent in 2 isolates, and antagonistic in 0 isolate. There were statistically significant differences between effective ratio and overall ratio of 18 MRSA isolates treated with combined antimicrobial agents (P values all above 0.01).

CONCLUSIONSFor burn wounds at middle and late stages infected with Staphylococcus aureus or Staphylococcus aureus and Fungus, low dose of SD-Ag or combination of above-mentioned antimicrobial agents can effectively control infection and decrease the adverse effect of antimicrobial agents on wound healing.

Adolescent ; Adult ; Aged ; Anti-Bacterial Agents ; administration & dosage ; adverse effects ; pharmacology ; Burns ; microbiology ; Child ; Child, Preschool ; Clotrimazole ; administration & dosage ; adverse effects ; pharmacology ; Drug Therapy, Combination ; Female ; Humans ; Infant ; Male ; Methicillin-Resistant Staphylococcus aureus ; drug effects ; isolation & purification ; Middle Aged ; Mupirocin ; administration & dosage ; adverse effects ; pharmacology ; Silver Sulfadiazine ; administration & dosage ; adverse effects ; pharmacology ; Young Adult