Therapeutic effects of dental pulp stem cells on vascular dementia in rat models

Dental pulp stem cells are a type of adult stem cells with strong proliferative ability and multi-differentiation potential. There are no studies on treatment of vascular dementia with dental pulp stem cells. In the present study, rat models of vascular dementia were established by two-vessel occlusion, and 30 days later, rats were injected with 2 × 10⁷ dental pulp stem cells via the tail vein. At 70 days after vascular dementia induction, dental pulp stem cells had migrated to the brain tissue of rat vascular dementia models and differentiated into neuron-like cells. At the same time, doublecortin, neurofilament 200, and NeuN mRNA and protein expression levels in the brain tissue were increased, and glial fibrillary acidic protein mRNA and protein expression levels were decreased. Behavioral testing also revealed that dental pulp stem cell transplantation improved the cognitive function of rat vascular dementia models. These findings suggest that dental pulp stem cell transplantation is effective in treating vascular dementia possibly through a paracrine mechanism. The study was approved by the Animal Ethics Committee of Harbin Medical University (approval No. KY2017-132) in 2017.

Therapeutic potential of dental pulp stem cell transplantation in a rat model of Alzheimer's disease

Dental pulp stem cells are dental pulp-derived mesenchymal stem cells that originate from the neural crest. They exhibit greater potential for the treatment of nervous system diseases than other types of stem cells because of their neurogenic differentiation capability and their ability to secrete multiple neurotrophic factors. Few studies have reported Alzheimer’s disease treatment using dental pulp stem cells. Rat models of Alzheimer’s disease were established by injecting amyloid-β1–42 into the hippocampus. Fourteen days later, 5 × 10⁶ dental pulp stem cells were injected into the hippocampus. Immunohistochemistry and western blot assays showed that dental pulp stem cell transplantation increased the expression of neuron-related doublecortin, NeuN, and neurofilament 200 in the hippocampus, while the expression of amyloid-β was decreased. Moreover, cognitive and behavioral abilities were improved. These findings indicate that dental pulp stem cell transplantation in rats can improve cognitive function by regulating the secretion of neuron-related proteins, which indicates a potential therapeutic effect for Alzheimer’s disease. This study was approved by the Animal Ethics Committee of Harbin Medical University, China (approval No. KY2017-132) on February 21, 2017.

Tanshinone IIA promotes the differentiation of bone marrow mesenchymal stem cells into neuronal-like cells in a spinal cord injury model

Background

Spinal cord injury (SCI) is one of the most severe central nervous system injuries. Currently, transplanting bone marrow mesenchymal stem cells (BMSCs) is considered a therapeutic option for SCI. Tanshinone IIA (TIIA) is one of the extracts obtained from Salvia miltiorrhiza Bunge, which has been shown to have some protective effects against SCI. The present research was aimed to explore whether TIIA would influence the fate of transplanted BMSCs in a rat model of SCI, especially with regard to their differentiation into neuronal cells.

Methods

Bone marrow mesenchymal stem cells were obtained from immature rats and identified using flow cytometry. After SCI, 1.0 × 10⁷ cells labeled with PKH67 were transfused into the injured spinal cord. TIIA was first injected into the tail vein (30 mg/kg) 1 h before surgery. From day 1 to day 7 post-SCI, TIIA was injected (20 mg/kg) per day at the same time. Recovery of locomotor function and histological regeneration of the spinal cord were compared among the groups, with the differentiation and distribution of BMSCs determined anatomically and biochemically by the expression of neural cell markers.

Results

Locomotor assessments showed that the rats in the BMSCs + TIIA group exhibited higher scores (19.33 ± 0.58) than those in the other groups (13.67 ± 1.53, 17.67 ± 0.58, 18.00 ± 1.73). The area of the cavity in the BMSCs + TIIA rats was smaller than that in the other groups (1.30 ± 0.56, 10.39 ± 1.59, 6.84 ± 1.18, 4.36 ± 0.69). Co-expression of glial fibrillary acid protein was observed in transplanted BMSCs, with a reduced rate in the BMSCs + TIIA group relative to that in the SCI group. In contrast, the expression levels of Nestin, neuron-specific nuclear protein (NeuN) and neurofilament protein 200 (NF200) were greatest in the transplanted cells in the BMSCs + TIIA group.

Conclusions

Tanshinone IIA treatment enhances the therapeutic effects of BMSC transplant on SCI, likely by promoting the differentiation of neuronal cells.

[1, 25-dihydroxyvitamin D3 promotes the apoptosis of inflammatory cells in acute experimental autoimmune encephalomyelitis: experiment with rats]

OBJECTIVE

To investigate the mechanism of rapid amelioration of the pathological changes in experimental allergic encephalomyelitis (EAE) by 1, 25-dihydroxyvitamin D(3) [1, 25-(OH)(2)D(3)].

METHODS

Forty Lewis rats were immunized with myelin basic protein in complete Freud's adjuvant so as to establish ESE animal models and then randomly divided into 4 equal groups: prevention group, fed with 1, 25-(OH)(2)D(3) since day 0 for 10 days, prevention-control group fed with peanut oil for 10 days, treatment group fed with 1, 25-(OH)(2)D(3) since the appearance of EAE symptoms (generally since day 10 or 11), and treatment-control group fed with peanut oil since the appearance of EAE symptoms. The clinical symptoms were scored since immunization till day 12 when the clinical symptoms reached the maximum level. The rats were sacrificed 13 days after sensitization with their brains and spinal cords taken out to undergo pathological examination, in situ TUNEL staining for detecting apoptotic cells, and semiquantitative immunohistochemical analysis to detect the inducible NO synthase (iNOS), FasL, and tumor growth factor (TGF)-beta 1, that might involve in the signal pathway of apoptosis. Peripheral blood samples were collected to isolate mononuclear cells (MNCs). The content of nitrite in the supernatant of MNC culture was evaluated.

RESULTS

The scores of clinical symptoms and the pathological changes of both the prevention and treatment groups decreased conspicuously and were significantly lower than their respective control groups (both P < 0.01). In contrast, the apoptosis indexes of the 2 1, 25-(OH)(2)D(3) administration groups were significantly higher than those of the control groups (all P < 0.01). The TUNEL positive cell rates in the brain and spinal cord of the treatment and prevention groups were all significantly higher than those of their corresponding control groups (P < 0.05, P < 0.01). The numbers of iNOS positive cells in the treatment and prevention groups were both lower than those of their corresponding control groups, which was in accord with the improvement of clinical signs and tissue lesions. The levels of nitrite in the supernatant of MNC culture of the treatment and prevention groups were higher than those of their corresponding control groups, but not significantly.

CONCLUSION

Administration of 1, 25-(OH)(2)D(3) rapidly ameliorates EAE symptoms by promoting the apoptosis of inflammatory cells. The elimination of infiltrating immune cells which reverses the pathological changes in central nervous system is associated with a favorable microenvironment provided by 1, 25-(OH)(2)D(3), such as decreasing of iNOS.