The experiment was conducted to study the dynamics of structural and functional changes development in skeletal muscles in a model of post-traumatic denervation and reinnervation of the limb, as well as under the conditions of the red bone marrow aspirate injection. At 8, 12, and 16 weeks after surgery (neurotomy and neurorrhaphy of the sciatic nerve), structural and functional changes were assessed and compared between groups. A separate task was to study the clinical manifestations of limb denervation. We also investigated functional changes during the target muscle reinnervation according to the EMG data and determined the changes that occur in the skeletal muscles using CT and MRI. The basis of biochemical studies was the muscle tissue state of peroxidation and enzymatic antioxidant system assessment in denervation-reinnervation period, and determination of the effects that the injection of bone marrow aspirate can cause.
Results of the conducted experimental study made it possible to establish the features of the red bone marrow aspirate influence on the dynamics of structural and functional changes in skeletal muscles at denervation-reinnervation process.
Using needle EMG, the nature of the denervation-reinervation process in skeletal muscles and the effect of bone marrow aspirate injection were demonstrated. It was found that the late injection of bone marrow aspirate contributes to the improvement of reinnervation, which was manifested in the registration of a larger number of motor unit potentials.
When analyzing CT and MRI data, it was determined that the bone marrow aspirate injection reduces the manifestations of muscle tissue edema. Morphological changes in the sciatic nerve after its transection and neurorrhaphy, and injection of the bone marrow aspirate into target muscles were studied. Axon sprouting into the distal segment of the nerve was detected in all cases, however, the data obtained indicate that the injection of bone marrow aspirate contributed to improving the dynamics of axon regeneration and had a positive effect on skeletal muscle reinnervation. An interesting observation is that the bone marrow aspirate injection improved the density of nerve fiber sprouting through the suture zone at an early stage. A higher density of peripheral nerve axon sprouting into the muscle was also detected. The above data can be considered as a morphological substrate, which is reflected by needle EMG.
Also, the morphological and ultrastructural data obtained during the experiment made it possible to formulate the hypothesis of the emergence of a state of equilibrium between the processes of regeneration and hypotrophy of muscle tissue in denervated muscles. The manifestation of this state is a simultaneous decrease in diameter and destruction of some muscle fibers and hypertrophy of others. It was noted that the injection of red bone marrow aspirate allows for prolonging the period of equilibrium between the processes of degeneration and regeneration in denervated skeletal muscle by slowing down the destruction of muscle fibers, thereby improving the prospects of the reinnervation process.
The dynamics of changes in the enzymatic and antioxidant systems of skeletal muscle after sciatic nerve transection and restoration, as well as the effect of red bone marrow aspirate on these systems, were studied. It was determined that lipid peroxidation products increased progressively at all times, but the injection of red bone marrow cells allowed to reduce their level, both by improving their utilization and inhibiting their synthesis. In addition, an increase in catalase activity was recorded as a manifestation of the antioxidant system activation. It was found that the red bone marrow aspirate injection has a positive effect on biochemical protective mechanisms in denervation damage to skeletal muscles.
Thus, the work analyzed the dynamics of the development of hypotrophic changes in skeletal muscles after denervation and at the stages of the reinnervation process under the influence of red bone marrow aspirate. Both the general clinical manifestations of limb denervation and the morpho-functional changes in the target muscles of the pelvic limbs of experimental animals were studied, and the effect of the bone marrow aspirate injection on the above indicators was also determined. Experimental study of functional, radiological, morphological, and biochemical changes in skeletal muscles of the lower leg reveal a certain positive effect of the red bone marrow aspirate injection, namely: a decrease in the manifestation of skeletal muscle edema, an increase in the number of motor unit potentials, a decrease in the manifestations of necroptosis and myocyte degeneration, a decrease in the number of lipid peroxidation products and an increase in the activity of antioxidant systems.
