Activation of Wnt3a signaling promotes myogenic differentiation of mesenchymal stem cells in mdx mice.

AIM: Duchenne muscular dystrophy (DMD) is an X-linked genetic muscular disorder with no effective treatment at present. Mesenchymal stem cell (MSC) transplantation has been used to treat DMD, but the efficiency is low. Our previous studies show that activation of Wnt3a signaling promotes myogenic differentiation of MSCs in vitro. Here we report an effective MSC transplantation therapy in mdx mice by activation of Wnt3a signaling. METHODS: MSCs were isolated from mouse bone marrow, and pretreated with Wnt3a-conditioned medium (Wnt3a-CM), then transplanted into mdx mice. The recipient mice were euthanized at 4, 8, 12, 16 weeks after the transplantation, and muscle pathological changes were examined. The expression of dystrophin in muscle was detected using immunofluorescence staining, RT-PCR and Western blotting. RESULTS: Sixteen weeks later, transplantation of Wnt3a-pretreated MSCs in mdx mice improved the characteristics of dystrophic muscles evidenced by significant reductions in centrally nucleated myofibers, the variability range of cross-sectional area (CSA) and the connective tissue area of myofibers. Furthermore, transplantation of Wnt3a-pretreated MSCs in mdx mice gradually and markedly increased the expression of dystrophin in muscle, and improved the efficiency of myogenic differentiation. CONCLUSION: Transplantation of Wnt3a-pretreated MSCs in mdx mice results in long-term amelioration of the dystrophic phenotype and restores dystrophin expression in muscle. The results suggest that Wnt3a may be a promising candidate for the treatment of DMD.

[A follow-up study on cognitive changes of mild cognitive impairment in the elderly].

OBJECTIVE: To observe and assess the cognitive changes of mild cognitive impairment (MCI) in the elderly. METHODS: A cohort study design was conducted among 47 patients with MCI and 21 control selected from the same convalescent camp, Montreal cognitive assessment (MoCA), mini mental state examination (MMSE) and clock drawing test (CDT) were performed to all subjects at the onset of study and 12 months later. RESULTS: The score of MMSE, CDT, MoCA and its subitems including visuospatial skill and delayed recall of MCI group were lower than the baseline after 12 months, with significantly decline in the score of MoCA (P = 0.041) and delay recall (P = 0.003). There was no obvious difference in the score of control between the baseline and that after 12 months. CONCLUSION: The decline of delayed recall occurred early and significantly, which may be a predictor in the conversion of mild cognitive impairment to dementia.

[A cross-sectional study of neurological disease in the veterans of military communities in Beijing].

OBJECTIVE: To investigate the prevalence of cognitive and motor disorders as well as emotional and sleep abnormality in the veterans from military communities in Beijing. METHODS: The participants underwent a comprehensive in-person evaluation including detailed neuropsychological testing, Hospital Anxiety and Depression Scale and special questionnaires for movement and sleep disorders. RESULTS: The overall prevalence of cognitive impairment, extrapyramidal diseases was 32.7%, 8.8%. The prevalence of mild cognitive impairment, dementia, Parkinson disease, essential tremor, anxiety and depression was 26.2%, 6.5%, 2.0%, 6.1%, 1.4% and 4.1% respectively. Prevalence of all kinds of sleep disorders ranged from 10.3% to 53.9%. The prevalence of cognitive impairment had no significant difference of sex, but were correlated to age and education, the correlation coefficient was 0.326 and -0.221 (P<0.01). CONCLUSION: Veterans from military communities had higher prevalence of cognitive impairment, extrapyramidal diseases and sleep disorders and lower that of anxiety and depression relatively.

[Comparison of transduction efficiencies of various gene vectors in human bone-marrow-derived mesenchymal stem cells].

OBJECTIVE: To compare the transduction efficiencies of adenoviral vector, adeno-associated viral vector, baculoviral vector, and plasmid vector in human bone-marrow-derived mesenchymal stem cells (hBMSCs). METHODS: The hBMSCs were cultured in vitro and transducted with the adenoviral vector, adeno-associated viral vector, baculoviral vector, and plasmid vector. The expression of target protein was observed by inverted fluorescent microscopy and flow cytometry. RESULTS: Inverted fluorescent microscopy showed that some of the hBMSCs after transduction expressed the green fluorescent protein (GFP) and the hBMSCs transducted with baculoviral vector expressed more GFP than those of other three vectors. Flow cytometry showed that the transduction efficiencies and mean fluorescence intensities of the adenoviral vector, adeno-associated viral vector, and plasmid vector were 42%, 37%, and 22% and 158, 115, and 77, respectively, which were significantly lower than those of baculoviral vector (70%, P < 0.01; 212, P < 0.05; respectively). CONCLUSION: Compared with the adenoviral vector, adeno-associated viral vector, and plasmid vector, the baculoviral vector has higher transduction efficiency in hBMSCs and therefore may be a more suitable gene vector for research in human gene therapy.

Comparative study of mesenchymal stem cells from C57BL/10 and mdx mice.

BACKGROUND: Human mesenchymal stem cells (MSCs) have been studied and applied extensively because of their ability to self-renew and differentiate into various cell types. Since most human diseases models are murine, mouse MSCs should have been studied in detail. The mdx mouse - a Duchenne muscular dystrophy model - was produced by introducing a point mutation in the dystrophin gene. To understand the role of dystrophin in MSCs, we compared MSCs from mdx and C57BL/10 mice, focusing particularly on the aspects of light and electron microscopic morphology, immunophenotyping, and differentiation potential. RESULTS: Our study showed that at passage 10, mdx-MSCs exhibited increased heterochromatin, larger vacuoles, and more lysosomes under electron microscopy compared to C57BL/10-MSCs. C57BL/10-MSCs formed a few myotubes, while mdx-MSCs did not at the same passages. By passage 21, mdx-MSCs but not C57BL/10-MSCs had gradually lost their proliferative ability. In addition, a significant difference in the expression of CD34, not Sca-1 and CD11b, was observed between the MSCs from the 2 mice. CONCLUSION: Our current study reveals that the MSCs from the 2 mice, namely, C57BL/10 and mdx, exhibit differences in proliferative and myogenic abilities. The results suggest that the changes in mouse MSC behavior may be influenced by lack of dystrophin protein in mdx mouse.

Wnt3a signaling promotes proliferation, myogenic differentiation, and migration of rat bone marrow mesenchymal stem cells.

AIM: To investigate the effects of the wingless-related MMTV integration site 3A (Wnt3a) signaling on the proliferation, migration, and the myogenic and adipogenic differentiation of rat bone marrow mesenchymal stem cells (rMSC). METHODS: Primary MSC were isolated and cultured from Sprague-Dawley rats and characterized by flow cytometry. Mouse L cells were transfected with Wnt3a cDNA, and conditioned media containing active Wnt3a proteins were prepared. Cell proliferation was evaluated by cell count and 5-bromodeoxyuridine incorporation assay. The migration of rMSC was performed by using a transwell migration and wound healing assay. The myogenic and adipogenic differentiation in rMSC were examined by light microscopy, immunofluorescence, and RT-PCR at different time points after myogenic or adipogenic introduction. RESULTS: Wnt3a signaling induced beta-catenin nuclear translocation and activated the Wnt pathway in rMSC. In the presence of Wnt3a, rMSC proliferated more rapidly than the control cells, keeping their differentiation potential. Moreover, Wnt3a signaling induced 2.62% and 3.76% of rMSC-expressed desmin and myosin heavy chain after being cultured in myogenic medium. The myogenic differentiation genes, including Pax7, MyoD, Myf5, Myf4, and myogenin, were activated after Wnt3a treatment. On the other hand, Wnt3a inhibited the adipogenic differentiation in rMSC through the downregulated expression of CCAAT/enhancer-binding protein alpha (C/EBPalpha) and peroxisome proliferator-activated receptor gamma (PPARgamma). Furthermore, Wnt3a promoted the migration capacity of rMSC. CONCLUSION: The results indicate that Wnt3a signaling can induce myogenic differentiation in rMSC. Wnt3a signaling is also involved in the regulation of the proliferation and migration of rMSC. These results could provide a rational foundation for cell-based tissue repair in humans.

[Construction of recombinant adenovirus including microdystrophin and expression in the mesenchymal cells of mdx mice].

Construction of recombinant adenovirus, which contain human microdystrophin, and then transfection into mesenchymal cells( MSCs) of mdx mice were done, and genetically-corrected isogenic MSCs were acquired; the MSCs transplantation into the mdx mice was then done to treat the Duchenne muscular dystrophy( DMD). Microdystrophin cDNA was obtained from recombinant plasmid pBSK-MICRO digested with restrictive endonuclease Not I ; the production was inserted directionally into pShuttle-CMV. The plasmid of pShuttle-CMV-MICRO was digested by Pme I , the fragment containing microdystrophin was reclaimed and transfected into E. coli BJ5183 with plasmid pAdeasy-1. After screening by selected media, the extracted plasmid of positive bacteria was transfected into HEK293 cells with liposome and was identified by observing the CPE of cells and by the PCR method. Finally, MSCs of mdx mice were infected with the culture media containing recombinant adenovirus, and the expression of microdystrophin was detected by RT-PCR and immunocytochemistry. Recombinant adenovirus including microdystrophin was constructed successfully and the titer of recombinant adenovirus was about 5.58 x 10(12) vp/mL. The recombinant adenovirus could infect MSC of mdx mice and microdystrophin could be expressed in the MSC of mdx mice. Recombinant adenovirus including microdystrophin was constructed successfully, and the microdystrophin was expressed in the MSC of mdx mice. This lays the foundation for the further study of microdystrophin as a target gene to correct the dystrophin-defected MSC for stem cell transplantation to cure DMD.

[Transfection and in vitro expression of human microdystrophin gene in rat mesenchymal stem cells].

OBJECTIVE: To construct the eukaryotic expression vector of human microdystrophin gene and observe its expression in rat mesenchymal stem cells (rMSCs) in vitro. METHODS: The plasmid PBSK-MICRO containing human microdystrophin cDNA was digested by restriction endonuclease, and the resultant microdystrophin fragment was inserted into the NotI site of pcDNA3.1(+) to prepare the eukaryotic expression vector-pcDNA3.1(+)/ microdystrophin, which was identified by endonuclease digestion and sequencing. The recombinant plasmid was transfected into rMSCs via lipofectamine, and after G418 selection, the expression of microdystrophin was detected by RT-PCR and indirect immunofluorescence assay. RESULTS: Microdystrophin gene fragment was correctly inserted into the plasmid pcDNA3.1(+), as conformed by sequencing and digestion with Not I and Hind III. The total mRNA of the transfected rMSCs was extracted and microdystrophin mRNA expression was found in the cells by RT-PCR. Indirect immunofluorescence assay for the protein expression of microdystrophin showed bright red fluorescence in the transfected rMSCs. CONCLUSION: Eukaryotic expression plasmid pcDNA3.1(+)/microdystrophin has been constructed successfully and microdystrophin can be expressed in transfected rMSCs in vitro, which may facilitate further research of Duchenne muscular dystrophy treatment by genetically modified allogeneic stem cell transplantation.