Background. Wounds of various aetiology are among the most frequent traumatic injuries. A prospective route to improve treatment of this nosology is the development of novel or advancement of the already on-stage dressing materials.Objectives. A comparative experimental assay of novel chitosan-based wound dressings in the healing of soft tissue wounds of different genesis using ultrasound to control biodegradation of the developed dosage form.Methods. Soft tissue wounds were modelled in experimental animals, conventional and lineage male rats, 275 (± 25) g body weight, and male rabbits, 2,900 (± 150) g weight, using a proprietary methodology (Patent on invention RU No. 2703709 dated 23 August, 2018).Two wound dressing samples selected as most promising and applicable in large-volume soft tissue aseptic wounds were tested in the final step of experiment. Ultrasound imaging of the model wound area during the sample material biodegradation was used to control the wound process in more detail. At all steps of experiment, animal models were handled in compliance with GOST 33044-2014 “Principles of Good Laboratory Practice”.Histomorphological assays were carried out with common protocols. Variation statistics was used for the data analysis, including the mean (M) and standard mean error (± m) estimation. The level of statistical significance was p < 0.05.Results. The animal assays and comprehensive evaluation of the obtained data revealed a high healing efficacy of chitosan-based wound coatings. The analyses of wound dressing samples have confirmed their predesigned properties: scaffold stability, capillarity, biodegradability and matrix capacities for the carried drug delivery.Additionally, ultrasound was proved effective to estimate dynamics of the coated wound healing and biopolymer biodegradation processes.Conclusion. The developed chitosan-based wound dressings exhibited efficacy in an experimental model of the soft tissues wound process.The use of ultrasound to study dynamics of the wound process and coating biodegradation provided an adequate congruence between the imaging and tissue histomorphology data, as well as the structure and properties of coating material.

Aim. To study morphological changes in aseptic and purulent soft-tissue wounds using the developed models in animal experiments.Materials and methods. The study was conducted on 70 white non-linear laboratory male rats aged 5 months and weighing 300–350 g. All the investigations were performed in accordance with ethical norms and documents regulating animal experiments. An experimental wound was simulated with the introduction of an implant into soft tissues using a layer-by-layer incision to the required depth. A sterile hydrophilic polymer implant was used for simulating an aseptic wound. A purulent wound was simulated using a porous polymer implant initially saturated with a suspension of a bacterial pathogen at a concentration of 10 5–10 12 microbial cells per 1 ml of suspension. The wounds were sutured layer by layer to form corresponding models. The implants was removed surgically on the 7th day. Statistical analysis of the study results was carried out by Windows 10 operating system using STATISTICA 6.1 (StatSoft Inc., USA) and Excel (Microsoft Offi ce 2010). The hypothesis of normal cumulative distribution in the samples was verifi ed via the Shapiro — Wilk and Kolmogorov — Smirnov tests. The signifi cance level threshold was set to p<0.05. Differences between quantitative parameters with a normal distribution were evaluated using the Student’s t-test, whereas independent samples were assessed via the non-parametric Mann — Whitney test. In all cases, differences were considered statistically signifi cant at p<0.05. The signifi cance level of the relationship between the two qualitative variables was verifi ed using the Pearson’s chi squared test (χ2 ). The study was approved at a meeting of the Independent Ethics Committee of the Kuban State Medical University (Minutes No. 63 of 21 May 2018).Results. The analysis of the obtained results has allowed optimal models for the formation of aseptic and purulent soft-tissue wounds in animal experiments to be selected.Conclusion. The proposed method of modeling aseptic and purulent wounds in animal experiments can be used in clinical and morphological studies of the wound process, as well as in assessing the effectiveness of various wound treatment methods.

Aim. To experimentally evaluate the efficacy of multi-layer chitosan-based wound dressings developed for dental purposes.Materials and Methods. Over the period from 2018 to 2019, an experimental study was conducted to evaluate the efficacy of multi-layer chitosan-based wound dressings developed for dental practice. Two types of dressings (No. 1c and 2c), the central part of which was modified with the introduction of a 10% iodopyron solution, were compared with the widely-used wound dressings Alvostaz (NKF Omega-Dent LLC, Russia) and Gelatamp (Roeko, Germany). The work involved 26 male Chinchilla rabbits, ten months old and weighing 2500 (±50) g. Evaluation of the efficacy of the wound dressings under study was carried by modelling the conditions of both aseptic and purulent-inflammatory processes (a total of 8 series of experiments). In experiments modelling the purulent-inflammatory process, a Ps. aeruginosa bacterial culture at a concentration of 109 CFU/ml was introduced into the alveolar socket after tooth extraction, 3 days before the application of a wound dressing sample. The dressings under study were applied on the wound for the period of 7 days. During the observation postoperative period, the animals were provided with free access to water and food. The sampling of the material for the study was carried out in the operating room on day 7.Results. According to the experimental results, chitosan-based wound dressings (No. 2c in particular) demonstrated high efficacy in experiments on animals (rabbits). The developed wound dressings perform mechanical protection and exhibit fuse effects, as well as are characterized by biodegradability and the ability to deliver medical agents contained therein to the damaged tissue.Conclusion. The proposed chitosan-based wound dressings showed sufficient efficiency on the modelled wound process in the alveolar socket of an extracted tooth. Dressing No. 2c was recognised to be optimal for infected and purulent wounds. This dressing has a dense outer layer, which structure retains frame functions for a long time, thus providing proper drainage of the pathological focus. Dressing No. 1c was established to be promising in cases without inflammatory processes in the extracted tooth socket, where high adhesion to surrounding tissues is initially required for ensuring the tightness and preservation of a blood clot in the wound.