Formulation and Preclinical Evaluation of Biodegradable Adhesive for Wound Closure

Introduction: Current methods for wound closure such as sutures or staples can cause inflammatory responses, which can cause prolong healing time and increase scar after healing, tissue adhesive is a promising way to close tissue via a minimum invasion in a surgical operation. Also, various applications of biological glues except for wound closure, have been reported in surgery, including tissue adhesion, hemostasis, and sealing of air and body fluid leaks. In this project, we formulated tissue adhesive based on natural materials that have the most biocompatibility, biodegradability, and non-toxic nature to the human body and conducted preclinical evaluations. Besides, the ease of availability and cost-friendly prices are a significant step towards conserving the environment by using renewable resources.Methods: In this project, at first, the optimal adhesive formulation was combined with different proportion of gelatin solution, honey, and chitosan. After making the optimal formulation of glue, the rheological test was performed to determine the effect of temperature on the viscosity of this glue. Because the water content of the formulation can affect its concentration and ultimately its rheology and in consequence adhesion, the water content of this glue was measured by TGA. Gelation of aqueous gelatin, honey, and chitosan solution was performed at 37°C during stirring with a magnetic stirring bar. The period required for the magnetic bar to stop stirring below this temperature was defined as the gelation time of the mixed solution. A universal tensile tester performed Lap-shear testing to investigate adhesive strength. The in-vitro cytotoxicity test (MTT) of adhesive was done on human melanoma cells A-375. Also, to evaluate the biodegradability of the formulation, it was kept in the vicinity of the simulated body fluid (SBF) and its degradation process was evaluated for up to 12 weeks. Animal studies were also performed on 36 Wistar male rats weighing 200 to 250 g. In this study, rats were randomly divided into 4 groups, each with 9 rats: 1) control group in which the wound was not treated by anything, 2) control group in which the 4.0 suture was used to close the wound, 3) control group in which the Bioglue® commercial adhesive was applied, and the group 4, which were treated with formulated adhesive to close the wound. A dorsal incisional wound of 2 cm was made on the back of the rats. In order to evaluate the wound healing, we measured the length of wounds on days 3, 7, 10 and 14 post-intervention and then the percentage of wound length and wound healing were determined on specific days and analyzed by SPSS software. For histological studies, rats were euthanized on days 3, 7, 14 post-intervention, and the back of their skin was excised in the area where the lesion was created and were evaluated for the presence of fibroblast and PMN cells as well as angiogenesis and epithelium growth.Results: The adhesive formulations in the ratio of 3: 2.5: 1 for gelatin 50% aqueous solution, honey, and chitosan 7%, respectively, showed the best adhesion performance. The viscosity of this adhesive was also measured 20360, 13100, and 5150 cP at 50, 60, and 70 °C, respectively. Also, the water content of this formulation was measured by TGA, and at 100 °C the weight loss resulting from evaporation was reported to be 54 %. The gelation time for this adhesive was also measured 10 minutes from 37 °C to jelly mode (32 °C). Also, the adhesion strength to the glass hydrophilic slide was measured 164 kPa and to the plastic hydrophobic slide was measured 80 kPa. According to the results obtained from the MTT assay, this formulation did not show toxicity and was not significantly different from negative control cells in terms of cells survival (P> 0.05). Evaluation of the degradability of this adhesive showed that a large amount of the formulation (83%) was degraded during the first two weeks and by the 12th week almost all the adhesive had been degraded. Comparison of wound healing by statistical analysis showed that there was no significant difference between groups in day 0 (P = 0.946), but in days 3, 7, 10 and 14 the length of wound in gelatin group was significantly less (P <0.001). Also, as expected, regarding histological evaluations including Epithelium growth, presence of polymorph nuclear leukocytes, fibroblasts, and angiogenesis, there was a significant difference between the group treated with the formulation of this study and other groups (P<0.05).Conclusion: Due to the obtained results and the sufficient and high adhesion strength of formulation as well as the non-toxicity and biodegradability of the product, as well as the availability of raw materials and its easy production, this adhesive is a suitable suture alternative for wound closure.

کلیدواژه ها:

Tissue Adhesive ، Gelatin ، Chitosan ، Honey ، Wound closure ، Biodegradable ، Non-toxic