Abstract

Objectives: to investigate the effects of chitosan/gelatin-based biopolymer films using for dura matter plasty in experiment.
Background: Biodegradable materials are of particular interest for dura matter (DM) reconstructive surgery.
Methods: The study involved 15 animals (white outbreed rats) weighing 250-300 g, which were divided into 3 groups: 1) DM plasty using chitosan films. 2)DM plasty using a chitosan film in combination with a gelatin film. 3) Autoplasty group. All animals were simulated penetrating traumatic brain injury (pTBI) with decompressive craniectomy of the skull and subsequent DM plasty with the indicated polymer films. In the trauma model, hemorrhagic contusion focus, decompressive bone window and DM incision are reproduced The animals were removed from the experiment at 42 days after surgery. The healing process was monitored by optical and confocal laser microscopy Carl Zeiss LSM-510 META with lenses Plan-Neofluar 40x/0.6 Korr, and camera Zeiss AxioCam. Luminescent images obtained by excitation with lamp UV HBO 100 with blue (FSet01 wf), green (FSet10 wf) and red (FSet20 wf) filters, as well as, by excitation by lasers with wavelength 405, 488, 543 nm. Histological sections were obtained and stained according to the standard method. 
The IR spectroscopy technique allows monitoring the dynamics of the TMO tissue regeneration process at various stages of injury healing; according to the analysis of IR absorption spectra, spectral markers of scar tissue, regenerating TMO and control intact TMO were determined; it is shown that the scar tissue is radically different from the tissues of the regenerating TMO in all groups, including the autoplasty group. This makes it possible to reliably distinguish scar tissue from other investigated tissues and polymer films; the most revealing effects were obtained in groups with chitosan, since chitosan has absorption bands different from the absorption bands of protein molecules (gelatin and collagen, and TMO in general), so the presence of chitosan-based films in tissue samples can be clearly identified by IR spectra; chitosan film with PEO does not degrade in 6 weeks, its residues are clearly identified by IR spectroscopy data. The additional use of gelatin accelerates the process of degradation of the chitosan film and contributes to the normal healing of the injury. 
Results: Corellation analysis of the densitometry results and microscopic parameters of the regenerated DM showed a direct relationship between the
characteristics of the regenerated DM and the intensity of collagen autofluorescence in the DM when excited by a laser with λ em- 488nm (green).
Significant correlation of selected indicators were established in all groups.
Conclusions: Chitosan/polyethylene oxide and gelatine biopolymer film (chitosan/PEO 7/3 wt%) is suitable for dura plasty under experimental conditions. 
The results of IR spectroscopy and histological data indicate that in the area of the biopolymer film implantation there are processes of normal regeneration of dural tissues, but scar tissue is not formed. 
The method of confocal microscopy shows different morphology of collagen fibers in tissue sections taken 3 and 6 weeks after treatment with biopolymer films of different composition, which indicates different duration of the healing process.
These studies allow us to conclude about the effectiveness of the chitosan/polyethylene oxide and its positive effect on the regeneration of dura mater in animals.