Macrophage Activation in the Dorsal Root Ganglion in Rats Developing Autotomy after Peripheral Nerve Injury

Autotomy, self-mutilation of a denervated limb, is common in animals after peripheral nerve injury (PNI) and is a reliable proxy for neuropathic pain in humans. Understanding the occurrence and treatment of autotomy remains challenging. The objective of this study was to investigate the occurrence of autotomy in nude and Wistar rats and evaluate the differences in macrophage activation and fiber sensitization contributing to the understanding of autotomy behavior. Autotomy in nude and Wistar rats was observed and evaluated 6 and 12 weeks after sciatic nerve repair surgery. The numbers of macrophages and the types of neurons in the dorsal root ganglion (DRG) between the two groups were compared by immunofluorescence studies. Immunostaining of T cells in the DRG was also assessed. Nude rats engaged in autotomy with less frequency than Wistar rats. Autotomy symptoms were also relatively less severe in nude rats. Immunofluorescence studies revealed increased macrophage accumulation and activation in the DRG of Wistar rats. The percentage of NF200+ neurons was higher at 6 and 12 weeks in Wistar rats compared to nude rats, but the percentage of CGRP+ neurons did not differ between two groups. Additionally, macrophages were concentrated around NF200-labeled A fibers. At 6 and 12 weeks following PNI, CD4+ T cells were not found in the DRG of the two groups. The accumulation and activation of macrophages in the DRG may account for the increased frequency and severity of autotomy in Wistar rats. Our results also suggest that A fiber neurons in the DRG play an important role in autotomy.

Upregulation of MicroRNA-199 (miR-199) Prompts the Apoptosis of K562 Cell in the Model of Mice with Leukemia

We investigated miR-199’s effect on the apoptosis of leukemia cells (K562) as so to provide reference idea for a new therapeutic target. 20 normal and healthy BALB/c nude rats were selected and equally and randomly assigned into inoculated group and blank group. The K562 cell was obtained and then divided into blank control group, miR-199 mimic group, and miR-199NC group followed by analysis of miR-199 expression, cell activity and apoptosis as well as the expression of Bax, Bcl-2 and PCNA. Inoculated group showed significantly higher proportion of leukemia cells and myeloid cells than blank group. The expression of miR-199 (3.22±0.03) in miR-199 mimic group was significantly higher than other two groups (P < 0.05) without difference between other two groups (P > 0.05). Bax expression (1.16±0.10) in miR-199 mimic group was significantly higher, whereas Bcl-2 (0.02±0.01) and PCNA (0.47±0.05) expression was significantly lower than other two groups. Upregulation of miR-199 could restrain the expression of Bcl-2 and PCNA through upregulation of Bax, indicating that miR-199 might be a new therapeutic target.

Comparison of bone regenerative capacity of donor-matched human adipose–derived and bone marrow mesenchymal stem cells

Adipose-derived stem cells (ASC) have been used as an alternative to bone marrow mesenchymal stem cells (BMSC) for bone tissue engineering. However, the efficacy of ASC in bone regeneration in comparison with BMSC remains debatable, since inconsistent results have been reported. Comparing ASC with BMSC obtained from different individuals might contribute to this inconsistency in results. Therefore, this study aimed to compare the bone regenerative capacity of donor-matched human ASC and BMSC seeded onto poly(l-lactide-co-ε-caprolactone) scaffolds using calvarial bone defects in nude rats. First, donor-matched ASC and BMSC were seeded onto the co-polymer scaffolds to evaluate their in vitro osteogenic differentiation. Seeded scaffolds and scaffolds without cells (control) were then implanted in calvarial defects in nude rats. The expression of osteogenesis-related genes was examined after 4 weeks. Cellular activity was investigated after 4 and 12 weeks. Bone formation was evaluated radiographically and histologically after 4, 12, and 24 weeks. In vitro, ASC and BMSC demonstrated mineralization. However, BMSC showed higher alkaline phosphatase activity than ASC. In vivo, human osteogenesis–related genes Runx2 and collagen type I were expressed in defects with scaffold/cells. Defects with scaffold/BMSC had higher cellular activity than defects with scaffold/ASC. Moreover, bone formation in defects with scaffold/BMSC was greater than in defects with scaffold/ASC, especially at the early time-point. These results suggest that although ASC have the potential to regenerate bone, the rate of bone regeneration with ASC may be slower than with BMSC. Accordingly, BMSC are more suitable for bone regenerative applications.

Comparative Behavioral Assessment of Lewis and Nude Rats after Peripheral Nerve Injury

Cell therapy has shown potential in the field of peripheral nerve repair, and research using rodents is a critical and essential step toward clinical development of this approach. Traditionally, most experimental peripheral nerve injuries are conducted in inbred Lewis or outbred Sprague–Dawley strains. However, transplantation of xenogeneic cells such as human-derived cells typically triggers rejection in these animals. An alternative approach is to use immunodeficient animals, such as athymic nude rats. The lack of functional T cells in these animals renders them more accommodating to foreign cells from a different host. Currently, no literature exists regarding sensorimotor behavioral assessment of nude rats after peripheral nerve injury. To this end, we compared the functional recovery during a 6-wk period of behavioral testing of Lewis and nude rats after unilateral sciatic nerve crushing injury. Three sensorimotor behavioral assessments were performed weekly: a ladder rungwalking task to assess slip ratio and cross duration, von Frey nociception testing to determine the paw withdrawal threshold thus monitoring the regaining of sensory function, and sciatic functional index evaluation to monitor the recovery of integrated motor function. Both strains demonstrated significant sensory and motor deficits in the first week after injury, with a slight regain of sensory function, reduced slip ratio, and increased sciatic functional index starting at 2 wk. No significance difference existed between nude and Lewis rats in their recovery courses. We conclude that nude rats are a suitable model for behavioral training and assessment for cell transplantation studies in peripheral nerve injury and repair.

Magnetic Targeted Delivery of Induced Pluripotent Stem Cells Promotes Articular Cartilage Repair

Cartilage regeneration treatments using stem cells are associated with problems due to the cell source and the difficulty of delivering the cells to the cartilage defect. We consider labeled induced pluripotent stem (iPS) cells to be an ideal source of cells for tissue regeneration, and if iPS cells could be delivered only into cartilage defects, it would be possible to repair articular cartilage. Consequently, we investigated the effect of magnetically labeled iPS (m-iPS) cells delivered into an osteochondral defect by magnetic field on the repair of articular cartilage. iPS cells were labeled magnetically and assessed for maintenance of pluripotency by their ability to form embryoid bodies in vitro and to form teratomas when injected subcutaneously into nude rats. These cells were delivered specifically into cartilage defects in nude rats using a magnetic field. The samples were graded according to the histologic grading score for cartilage regeneration. m-iPS cells differentiated into three embryonic germ layers and formed teratomas in the subcutaneous tissue. The histologic grading score was significantly better in the treatment group compared to the control group. m-iPS cells maintained pluripotency, and the magnetic delivery system proved useful and safe for cartilage repair using iPS cells.