DEPENDENCE OF THE RESTORATIVE EFFECT OF MACROPOROUS POLY(N-[2- HYDROXYPROPYL]-METHACRYLAMIDE HYDROGEL ON THE SEVERITY OF EXPERIMENTAL LACERATIVE SPINAL CORD INJURY

Abstract

restoration of the spinal cord function presents a most severe biomedical issue nowadays. The aimof the study was to detect the macroporous poly(N-[2-hydroxypropyl]-methacrylamide hydrogel (PHPMA-hydrogel,HG) restorative effect dependence on the severity of the laceration spinal cord injury in young organisms.The male rats sample (~1-month-old, ~50 g, inbred Wistar line) was represented with 4 experimental groups: 1)spinal cord lateral hemisection at the level of ~Т12–Т13 segments (Sect; n=11); 2) spinal cord lateral hemiexcision~1 mm long at the similar level (Exc; n=8); 3) spinal cord lateral hemisection at the similar level with immediateimplantation of the hydrogel fragment into the trauma region (HGsect; n=11); 4) spinal cord lateral hemiexcisionat the similar level with immediate implantation of the hydrogel fragment into the affected region (HGexс; n=6).The motor function and spasticity of the paretic hindlimb was estimated respectively by the technically modifiedBasso–Beattie–Bresnahan (ВВВ) and Ashworth, conditionally blinded to individual characteristics of all operatedanimals and previous study results. The observation lasted for ~5 months. The criteria of non-inclusion wereas follows: the ipsilateral hindlimb function level in a week after the injury >9 points ВВВ, and the contralateralhindlimb function level during prolonged period ≤14 points ВВВ. The results were interpreted and presentedaccording to the standardized time scale with interpolatory representation of the motor function and spasticityindividual level in certain cases. Asymptotic stage differences between the studied groups and subgroups werestated during the first three weeks as well as in 8 weeks and 3 months after the injury. We found out that in aweek after injury the motor function level in group Exc made up 0.9±0.5 points ВВВ, in group HGexc — 3.6±1.2points, in group Sect — 5.9±1.1 points, in group HGsect — 6.0±1.0 points. In 5 months the motor function levelin group Sect made up 9.5±1.0 points ВВВ, in group HGsect — 9.5±1.1 points, in group Exc — 0.8±0.3 points,in group HGexc — 4.5±1.8 points. At the same study stage the spasticity level in groups Sect and HGsect was,respectively, 0.8±0.2 and 0.8±0.3 points Ashworth, in group HGexc — 1.8±0.7 points, in group Exc — 3.6±0.3points. Throughout the study no significant differences in groups Sect and HGsect have been detected, and ingroups Exc і HGexc such differences were detected only in 5 weeks after the injury. The considerable difference ofspasticity in groups Sect and HGsect was noted in 1 week after the injury, in groups HGexc and Exc — during first2 months of the experiment. In groups Sect and Exc reliable difference of both motor function and spasticity levelwas found at all study stages. In groups HGsect and HGexc considerable difference of the motor function levelwas characteristic at all stages, except for the end of the 1st and 7th weeks, whereas spasticity level differences throughout the study remained insignificant. So, the tested hydrogel in young organisms shows positive effect onlywith severe trauma stages accompanied with extensive spinal cord defect.