Improvement of Cell Cycle Lifespan and Genetic Damage Susceptibility of Human Mesenchymal Stem Cells by Hypoxic Priming

Hypoxic culture is widely recognized as a method to efficiently expand human mesenchymal stem cells (MSCs) without loss of stem cell properties. However, the molecular basis of how hypoxia priming benefits MSC expansion remains unclear. We report that hypoxic priming markedly extends the cell cycle lifespan rather than augmenting the multipotency of MSC differentiation lineage. Hypoxic priming does not affect to chromosome damage but significantly attenuates the susceptibility of chromosome damage. Our results provide important evidence that multipotency of human MSCs by hypoxic priming is determined by cell cycle lifespan.

Analyzing micronucleus test in patients with occupational chronic benzene poisoning / 中国职业医学

OBJECTIVE: To analyze chromosome damage and its possible influencing factors in patients with occupational chronic benzene poisoning. METHODS: Fifty patients with occupational chronic benzene poisoning were selected as chronic benzene poisoning group,and 53 workers without occupational exposure to benzene and other toxic substances were chosen as control group by using convenience sampling method. Questionnaire and routine blood test were conducted on all study subjects. Micronucleus rate test was performed by micronucleus blocking cytokinesis assay. RESULTS: Peripheral blood tests of chronic benzene poisoning group showed significantly reduced hemoglobin level,counts of red blood cells,white blood cells,platelets,lymphocytes and neutrophils( P < 0. 01),and higher lymphocyte micronucleus rates compared to control group( !: 6. 26‰ vs 3. 91‰,P < 0. 01). The proportion of increased lymphocyte micronucleus rate in chromic benzene poisoning group was also higher than that in control group( 46. 0% vs 5. 7%,P < 0. 01). The multivariate Poisson analysis results indicated that the time after disengagement from benzene exposure was the influencing factor of micronucleus rate in chronic benzene poisoning group( P < 0. 05),after adjusting the confounding factors of gender,age,smoking status,alcohol drinking status and working age of benzene exposure. CONCLUSION: Occupational chronic benzene poisoning leads to increase of chromosome damage in lymphocytes of patients. The time after disengagement from benzene exposure was positively correlated with chromosome damage.

Protective effects of solvent fractions of Mentha spicata (L. ) leaves evaluated on 4-nitroquinoline-1-oxide induced chromosome damage and apoptosis in mouse bone marrow cells

Spearmint leaves (Mentha spicata L.) contain high levels of antioxidants that are known to protect against both exogenous and endogenous DNA damage. In this study, the protective effects of the hexane fraction (HF), chloroform fraction (CF) and ethyl acetate fraction (EAF) in an ethanol extract from M. spicata were evaluated against 4-nitroquinoline-1-oxide (4-NQO) induced chromosome damage and apoptosis in bone marrow cells of Swiss albino mice. Two (EAF; 80 and 160 mg/ kg body weight - bw) or three (HF and CF; 80, 160 and 320 mg/ kg bw) doses of solvent fractions or vehicle control (25 percent DMSO in water) were administered orally for five consecutive days. Upon the sixth day, 4-NQO was injected intraperitoneally. The animals were killed the following day. Other control groups were comprised of animals treated with either the vehicle control or the various doses of solvent fractions, but with no 4-NQO treatment. 4-NQO induced micro-nucleated polychromatic erythrocytes (MnPCEs) in all the test groups. However, pre-treatment of animals with the solvent fractions significantly reduced the 4-NQO-induced MnPCEs as well as the percentage of apoptotic cells. The reduction of both MnPCE and apoptosis was more evident following the pre-treatment of animals with 160 mg/kg bw EAF.

Research Progress on Genotoxity of Polycyclic Aromatic Hydrocarbons / 环境与健康杂志

Polycyclic aromatic hydrocarbons(PAHs) is a class of organic pollutants widely distributed in various environmental medium,and human exposure can occur by many routes (inhalation,ingestion,and skin contact),regardless of the source. PAHs can seriously impact human health and environment due to their high toxicity,stability. Studies on the toxicity of PAHs have involved in many fields,such as genotoxicity,hepatotoxicity,developmental toxicity,carcinogenesis and so on. The development of studies on genotoxicity of PAHs was reviewed in this paper,including DNA damage,chromosome damage and genetic susceptibility.