No abstract

In the present study, a poly- l -lactide/silk fibroin (PL-SF) bilayer scaffold seeded with allogenic bone marrow stromal cells (BMSCs) was investigated as a potential approach for bladder tissue engineering in a model of partial bladder wall cystectomy in rabbits. The inner porous layer of the scaffold produced from silk fibroin was designed to promote cell proliferation and the outer layer produced from poly- l -lactic acid to serve as a waterproof barrier. To compare the feasibility and efficacy of BMSC application in the reconstruction of bladder defects, 12 adult male rabbits were divided into experimental and control groups (six animals each) that received a scaffold seeded with BMSCs or an acellular one, respectively. For BMSC tracking in the graft in in vivo studies using magnetic resonance imaging, cells were labeled with superparamagnetic iron oxide nanoparticles. In vitro studies demonstrated high intracellular incorporation of nanoparticles and the absence of a toxic influence on BMSC viability and proliferation. Following implantation of the graft with BMSCs into the bladder, we observed integration of the scaffold with surrounding bladder tissues (as detected by magnetic resonance imaging). During the follow-up period of 12 weeks, labeled BMSCs resided in the implanted scaffold. The functional activity of the reconstructed bladder was confirmed by electromyography. Subsequent histological assay demonstrated enhanced biointegrative properties of the PL-SF scaffold with cells in comparison to the control graft, as related to complete regeneration of the smooth muscle and urothelium tissues in the implant. Confocal microscopy studies confirmed the presence of the superparamagnetic iron oxide nanoparticle-labeled BMSCs in newly formed bladder layers, thus indicating the role of stem cells in bladder regeneration. The results of this study demonstrate that application of a PL-SF scaffold seeded with allogenic BMSCs can enhance biointegration of the graft in vivo and support bladder tissue regeneration and function.

No abstract

The problem of mobility of spinal patients is generally solved by using the wheelchair. Also, methods providing walking activity of spinal patients by multicharmel computer stimulation of muscles, nerve trunks [22], and zones of the spinal cord are under development. The specific feature of the method described in this work is that it uses the locomotion control function of the spinal cord.A hypothesis of Professor Yu. T. Shapkov suggests that the human spinal cord contains interneuronal structures providing automatic walking movements (spinal generators of locomotion) and that these structures can be activated externally [4, 5,[24][25][26]. He developed and took charge of a project for investigating this problem. Clinical studies were carried out at two clinics of the Scientific-Research Institute for Phthisiology and Pulmonology (Heads, Professor A. E. Garbuz and Professor IC N. Kovalenko). The results described In this work were obtained at the Center for Children's Surgical Tuberculosis in 1994-1995. In healthy subjects, the activity of spinal generators of locomotion is controlled by upper segments of the higher nervous system and it is not manifested itself. If the regulatory connections between spinal cord and brain are lost, the locomotor structures of the spinal cord remain conserved, although uncontrolled. Therefore, the problem of arrangement of external artificial control of the internal activity of the spinal generators of locomotion is rather important.Electrostimulation of spinal cord structures in paralyzed patients with vertebral pathology (vertebrogenic myelopathy) carried out at the Center for Children's Surgical Tuberculosis induced basic coordinated movements of the legs.Parameters and zones of electrostimulation providing most efficacious induction of locomotion and optimum external conditions for activation of walking were found. A total of 14 child patients with paralyses and pareses underwent treatment by this method for two years. The method is found to be efficacious for rehabilitation of motor activity of the spinal patients. However, at the present time the method is quite laborious because it requires individual selection of electrostimulation parameters and continuous monitoring of patients by skilled personnel.Further research into induced locomotion (including neurophysiological and biomechanical studies) would provide the opportunity for developing "a walking pacemaker generator" (by analogy with the cardiac pacemaker). Spinal Generators of Locomotion in Animals and HnmansThe spinal cord of animals is studied significantly better than the human spinal cord. This is because many methods of study permissible in the case of animals are not applicable to studies of the human body. The concepts of locomotor function of the spinal cord are based on studies of decerebrized and spinal animals [3, 13, 16, 21, 27, 28, 29]. Taken together, these concepts can be regarded as a theory of spinal generators of walking, i.e., functional associations of interneurons of several segments producing...