ADSCs show potential for restoring degenerative discs and may prove effective in the treatment of IVD.

In this study, the authors explored the effect of human mesenchymal stem cell (MSC) implantation on the restoration of degenerative intervertebral discs (IVDs) in the rat. A unique rat coccygeal model was used to investigate the effects of transplanting human MSCs and to examine MSC survival in degenerative discs. MSC implantations into rat coccygeal IVDs were performed at 2 weeks postinjury. Radiologic and histologic evaluations were performed at 2, 4, 6, and 8 weeks post-injury. MSCinjected segments (TS) retained disc height and signal intensity, but injured non-injected segment (IS) progressively lost disc height. Pathological results revealed that the TS group showed relative restoration of the inner annulus structure; however, the IS group showed destruction of the inner annulus structure. Immunohistochemical staining using Anti-Human Nucleic Antibody (#MAB1281 Chemicon) revealed positive staining in the TS group at 2 weeks posttransplantation (4 weeks post-injury). This study shows that human MSCs survive for 2 weeks after transplantation into the IVDs of rats, and that MSCs increased the heights and signal intensities of intervertebral disc.

Intracortical microstimulation (ICMS) is a technique that was developed to derive movement representation of the motor cortex. Although rats are now commonly used in motor mapping studies, the precise characteristics of rat motor map, including symmetry and consistency across animals, and the possibility of repeated stimulation have not yet been established. We performed bilateral hindlimb mapping of motor cortex in six Sprague-Dawley rats using ICMS. ICMS was applied to the left and the right cerebral hemisphere at 0.3 mm intervals vertically and horizontally from the bregma, and any movement of the hindlimbs was noted. The majority (80%±11%) of responses were not restricted to a single joint, which occurred simultaneously at two or three hindlimb joints. The size and shape of hindlimb motor cortex was variable among rats, but existed on the convex side of the cerebral hemisphere in all rats. The results did not show symmetry according to specific joints in each rats. Conclusively, the hindlimb representation in the rat motor cortex was conveniently mapped using ICMS, but the characteristics and inter-individual variability suggest that precise individual mapping is needed to clarify motor distribution in rats.Graphical Abstract

Objective: Human mesenchymal stem cell (MSC) is known to have therapeutic effect in spinal cord injury (SCI), but the optimal therapeutic time window and survival pattern is not well known. The authors evaluated the treatment effect of MSC in the respect of injection time and survival rate in spinal cord injured rats. Methods: In experiment I, SCI is performed by New York State University (NYU) Impactor in 30 rats. Human MSCs were injected intramedullarily with 5 groups. The animals were grouped with Group 1 (injury only), Group 2 (immediate MSC injection), Group 3 (injection after 3 days), Group 4 (injection after 1 week), Group 5 (injection after 2 weeks), and Group 6 (injection after 4 weeks). The Basso Beattie Bresnahan (BBB) locomotor scale was evaluated during 8 weeks after SCI in all the animals, and then the spinal cords were stained with H&E and antinucleic acid staining (Antinuclei ®). In experiment II, MSC were injected at 1 week after SCI. After that, cord tissue were stained with antinucleic acid at 1 week (n=5), 2 weeks (n=5), and 3 weeks (n=5) after injection. Results: In experiment I, BBB score improvement at 8th week after SCI were statistically significant at Group 4, 5, 6 compared to Group 1. The cavity size were not significantly different in each group. In the antinucleic acid staining, the MSCs could not be observed within the cords. In experiment II, stained cell numbers at each group were significantly different. Conclusion: In this study, the authors observed that neurological recovery after SCI in rats were improved by human MSCs which were injected intramedullarily at 1, 2, or 4 weeks after SCI and the injected cells could not survive over 4 weeks. Therefore, the neuroprotective effect by MSCs is supposed to be ocurred in the early period of injection time when the MSCs survive.