Objective]To measure and compare the MRI artifacts caused by common metal ic dental materials and common ceramic dental materials on different field-strength magnets.[Methods] A total of 3 common metal ic dental materials and 2 common ceramic dental materials were tested with 0.35T, 1.5T and 3.0T MR imagers. The artifact areas on these 3 different field-strength magnets were measured and statistical y compared. [Results]Zirconia in three field magnetic resonance(NMR) in T1 and T2 as no artifacts, casting porcelain, metal al oy, nickel chromium al oy and CoCr-al oy in three fields magnetic resonance(NMR) in T1 and T2 as al can produce different degree of artifacts, and artifacts area increased in turn. Cobalt chromium al oy and nickel chromium al oy measurements on the high side, the cobalt chromium al oy than other four kinds of materials on the high side( P<0.05),high nickel-chromium al oy was precious metal al oy, casting porcelain( P<0.05). [Conclusions]Commonly used metal ic dental materials could cause MR artifacts and image degradation. Compared with that on 0.35T, the artifact was increased on 1.5T magnet. Compared with that on 1.5T, the artifact was increased on 3.0T magnet.

BACKGROUND:Co-transplantation of bone marrow mesenchymal stem cells (BMSCs) and hematopoietic stem cells (HSCs) can improve the survival rate following radiation damage. OBJECTIVE:To review the mechanisms of BMSCs in hematopoietic reconstitution and immunomodulation after radiation damage. METHODS: Relevant articles included in the Web of science from 2005 to 2016 were retrieved, and the keywords were mesenchymal stem cells; radiation; radiation injury; hematopoietic stem cells; hematopoietic reconstitution; immunomodulatory in English. Then we sorted and analyzed the articles which were closely related to the theme. RESULTS AND CONCLUSION:BMSCs can repair broken DNA double bonds by autophagy and HR/NHEJ pathway; support and protect HSCs by intercellular interactions and paracrine action; and repair radiation-induced hematopoietic injury by inhibiting inflammation and immune responses to maintain HSC homeostasis. Therefore, BMSCs may function as an effective treatment for radiation-induced hematopoietic injury.

BACKGROUND: Mesenchymal stem cells attract extensive attention because of good biological characteristics and broad prospects, but the cells gradually show the characteristics of the aging with the increase of individual age or incubation time in vitro. Nonhuman primates have similar biological characteristics with human being, and have unique advantage in the animal model and disease treatment research.OBJECTIVE: To analyze the difference in proliferation and differentiation of bone marrow mesenchymal stem cells from macaques at different ages and to explore the effect of age on bone marrow mesenchymal stem cells and the possible mechanism.METHODS: Bone marrow samples from male macaques aged < 3 years and over 20 years were collected through bone marrow puncture, and divided into young group and elder group, with three macaques in each group. Then, bone marrow mesenchymal stem cells were isolated and cultured in vitro, and the morphological changes, proliferation and differentiation ability were observed. Age-related beta-galactosidase staining was performed, and protein microarray and ELISA were used to detect cytokine levels.RESULTS AND CONCLUSION: With age, the proliferation and differentiation of bone marrow mesenchymal stem cells from the elder macaques were reduced significantly, and the number of senescent cells increased significantly; the levels of interleukin-1b, interleukin-4, interleukin-6, tumor necrosis factor α and vascular endothelial growth factor were elevated obviously, the levels of heparin-binding basic fibroblast growth factor and placental growth factor were reduced. These findings indicate that the body's aging lead to the reduction in the proliferation, differentiation and cytokine secretion of bone marrow mesenchymal stem cells.

Objective To establish a method for isolation of cynomolgus monkey umbilical cord mesenchymal stem cells.Methods Fresh cynomolgus monkey umbilical cord was directly minced into pasty fine pieces, and the pieces were cultured in tissue flask with DMEM/F12 medium supplemented with 10% fetal bovine serum.The morphological characteristics of the resulting cells were examined, and their expression of mesenchymal cell surface markers were analyzed by flow cytometry.The multidifferentiation potential was examined in vitro, too.Results The fibroblast-like cells were successfully isolated from the fresh umbilical cord by an adherent culture procedure.These adherent cells expressed mesenchymal markers including CD29, CD44, and CD90, and also could be induced to differentiate into adipocytes, osteoblasts and chondrocytes.Conclusion Mesenchymal stem cells can be isolated from fresh cynomolgus monkey umbilical cord by using an adherent culture procedure.

As human life expectancy continues to increase and the birth rate continues to decline, the phenomenon of aging is becoming more prominent worldwide. Therefore, addressing the problems associated with global aging has become a current research focus. The main manifestations of human aging are structural degeneration and functional decline of aging tissues and organs, quality of life decline, decreased ability to resist diseases, and high incidence rates of a variety of senile degenerative diseases. Thus far, no ideal treatments have been found. Stem cell (SC) therapies have broad application prospects in the field of regenerative medicine due to the inherent biological characteristics of SCs, such as their plasticity, self-renewal, and multidirectional differentiation potential. Thus, SCs could delay or even reverse aging. This manuscript reviews the causes of human aging, the biological characteristics of SCs, and research progress on age reversal.

BACKGROUND:Spleen has the functions of blood storage,hematopoiesis,and immunity.With the increase of age,the structural degeneration and functional decline of spleen lead to the impairment of immune system function,thus accelerating the aging process of the body.The treatment of spleen aging in tree shrews with highly active umbilical cord mesenchymal stem cells has not been reported. OBJECTIVE:To explore the intervention effect and mechanism of highly active umbilical cord mesenchymal stem cells on spleen aging in tree shrews. METHODS:Highly active umbilical cord mesenchymal stem cells were isolated,cultured,and obtained from the umbilical cord tissue of newborn tree shrews by caesarean section.The differentiation abilities of adipogenesis,osteogenesis,and chondrogenesis were detected by three-line differentiation kit.Cell cycle and surface markers were detected by flow cytometry.The second generation of highly active umbilical cord mesenchymal stem cells were transfected with Genechem Green Fluorescent Protein with infection complex values of 100,120,140,160,180,and 200,respectively,to screen the best transfection conditions.After transfection,the fourth generation of highly active umbilical cord mesenchymal stem cells was injected into the tail vein of tree shrews in the elderly treatment group.The young control group and the aged model group were not given special treatment.After 4 months of treatment,the spleen tissue was taken and the structure of the spleen was observed by hematoxylin-eosin staining.β-Galactosidase staining was used to detect the activity of aging-related galactosidase.Immunohistochemical staining was used to detect the expression levels of p21 and p53 proteins.Ki67 and PCNA immunofluorescence staining was used to detect cell proliferation activity.Immunofluorescence staining was used to detect the expression levels of spleen autophagy protein molecules Beclin 1 and APG5L/ATG5.Reactive oxygen species fluorescence staining was used to detect the content of reactive oxygen species in spleen tissue.CD3 immunofluorescence staining was used to detect the change of the proportion of total T lymphocytes.The secretion levels of interleukin 1β and transforming growth factor β1 in spleen were detected by enzyme linked immunosorbent assay.The distribution of highly active umbilical cord mesenchymal stem cells labeled with green fluorescent protein in spleen tissue was observed by DAPI double staining of nucleus. RESULTS AND CONCLUSION:(1)Highly active umbilical cord mesenchymal stem cells grew in a short spindle shape with fish-like growth,with a large proportion of G0/G1 phase,and had the potential to differentiate into adipogenesis,osteogenesis,and chondrogenesis.(2)Multiplicity of infection=140 and transfection for 72 hours were the best conditions for labeling tree shrews highly active umbilical cord mesenchymal stem cells with Genechem Green Fluorescent Protein.(3)Compared with the aged model group,in the aged treatment group,the spleen tissue cells of tree shrews were arranged closely,and the area of white pulp was increased(P<0.01);the boundary between red pulp and white pulp was clear;the proportion of germinal centers did not show statistically significant difference(P>0.05).The activity level of galactosidase related to spleen tissue aging was decreased(P<0.001),and the expression levels of aging protein molecules p21 and p53 were down-regulated(P<0.001).The expression levels of proliferation-related molecules Ki67 and PCNA were up-regulated(P<0.001,P<0.05);expression levels of autophagy-related molecules Beclin 1 and APG5L/ATG5 were up-regulated(P<0.001),and the content of reactive oxygen species decreased(P<0.001),and the proportion of CD3+T cells increased(P<0.05).The secretion level of interleukin 1β in the aging-related secretion phenotype decreased(P<0.001);no significant difference was found in transforming growth factor β1 level(P>0.05).Compared with the young control group,the above indexes were significantly different in the elderly treatment group(P<0.05).(4)Green fluorescent cells labeled with green fluorescent protein were observed in spleen tissue of tree shrews the elderly treatment group by frozen tissue section observation.The results show that intravenous infusion of highly active umbilical cord mesenchymal stem cells can migrate to spleen tissue,inhibit the production of reactive oxygen species,down-regulate the expression of aging-related proteins,induce autophagy,promote cell proliferation,reduce chronic inflammation,and then improve the structure and function of spleen tissue.