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Objective: To explore the biological mechanisms underlying Angelica sindsis polysaccharide (ASP) -induced aging of human-derived leukemia stem cells (LSCs) in vitro., Method: Acute myelogenous leukemia stem cells were isolated by magnetic activated cell sorting (MACS). The ability of LSC proliferation treated by various concentration of ASP(20-80 mg · L(-1)) in vitro for 48 hours were tested using cell counting Kit-8 ( CCK8) , colony forming were evaluated by methylcellulose CFU assay. The ultra structure changes of AML CD34+ CD38- cells were analyzed by transmission electron microscopy. The aging cells were detected with senescence-β-galactosidase Kit staining. Expression of aging-related p53, p21, p16, Rb mRNA and P16, Rb, CDK4 and Cyclin E protein were detected by quantitative reverse transcription polymerase chain reaction( qRT-PCR) and Western blotting, respectively., Result: The purity of the CD34 + CD38 - cells is (91.15 ± 2.41)% after sorted and showed good morphology. The proliferation of LSC was exhibited significantly concentration-dependent inhibited after exposure to various concentration of ASP. Treated by 40 mg · L(-1) ASP for 48 hours, the percentage of positive cells stained by SA-β-Gal was dramatically increased (P < 0.01) and the colony-formed ability has been weakened (P < 0.01). The observation of ultrastructure showed that cell heterochromatin condensation and fragmentation, mitochondrial swelling, lysosomes increased in number. Aging-related p53, p21, p16, Rb and P16, Rb were up-regulated, protein regulatory cell-cycle CDK4 and Cyclin E were down-regulated. ASP may induce the senescence of LSCs effectively in vitro, P16-Rb cell signaling pathway play a significant role in this process., Conclusion: ASP can induce human leukemia stem cell senescence in vitro, the mechanism involved may be related to ASP regulation P16-Rb signaling pathways.

Leukemia stem cells (LSCs) play important roles in leukemia initiation, progression and relapse, and thus represent a critical target for therapeutic intervention. Hence, it is extremely urgent to explore new therapeutic strategies directly targeting LSCs for acute myelogenous leukemia (AML) therapy. We show here that Angelica sinensis polysaccharide (ASP), a major active component in Dong quai (Chinese Angelica sinensis), effectively inhibited human AML CD34+CD38? cell proliferation in vitro culture in a dose-dependent manner while sparing normal hematopoietic stem and progenitor cells at physiologically achievable concentrations. Furthermore, ASP exerted cytotoxic effects on AML K562 cells, especially LSC-enriched CD34+CD38? cells. Colony formation assays further showed that ASP significantly suppressed the formation of colonies derived from AML CD34+CD38? cells but not those from normal CD34+CD38? cells. Examination of the underlying mechanisms revealed that ASP induced CD34+CD38? cell senescence, which was strongly associated with a series of characteristic events, including up-regulation of p53, p16, p21, and Rb genes and changes of related cell cycle regulation proteins P16, P21, cyclin E and CDK4, telomere end attrition as well as repression of telomerase activity. On the basis of these findings, we propose that ASP represents a potentially important agent for leukemia stem cell-targeted therapy.

We have investigated oxidized low-density lipoprotein (ox-LDL) induced senescence in hematopoietic stem cells (HCs). Mouse Sca-1+ HCs were separated and purified using the magnetic activated cell sorting technique. Ox-LDL induced significant senescence in HCs measured by SA-β-Gal staining, and reduced CFU-Mix colony-forming capacity, arresting cells at G0/G1 phase. In agreement with the cell cycle arrest, ox-LDL markedly reduced the expression of CDK4, cyclin D, and cyclin E. As possible contributing factors for cell senescence, ox-LDL also induced cellular oxidative stress and reduced telomerase activity., (© 2013 International Federation for Cell Biology.)

Objective: The effect of angelica sinensis polysaccharides (ASP) on the production of reactive oxygen specie (ROS), the capability of total anti-oxidant (T-AOC), and the expression of p16 in mRNA level in mice hematopoietic stem cells (HSCs) were observed to explore the underlying mechanism that ASP delay aging of HSCs in vivo., Method: C57BL/6J mice were randomly divided into normal group, aging group, and the above groups treated with ASP. Mice were uniformly explored in X-ray (3.0 Gy/8 F) to erect model of aging. Normal and aging ASP intervention groups mice were treated with ASP by intragastric administration, while normal and aging groups were treated with equal-volume NS during X-ray irradiation. Mice HSCs were isolated by magnetic cell sorting and cultured in vitro. Senescence-associated beta-galactosidase (SA-beta-Gal) staining was used to detect aging HSCs. Cell cycles analysis and CFU-Mix cultivation were used to evaluate the capability of self-renewing and colony forming in HSCs. The production of ROS in HSCs was evaluated by flow cytometry analysis and immunofluorescence assess, respectively. T-AOC was detected by chemical colorimetric method. The expression of p16 was determined by real-time quantitative PCR (qRT-PCR)., Result: Exogenous X-ray irradiation induced HSCs aging was compared with normal group without irradiation. Biological feature of HSCs in aging group with X-ray irradiation as follows: The percentage of SA-beta-Gal positive cells, the ratio of G1 stages and the production of ROS were significantly increased , the expression of p16 in mRNA level was also upregulated. The capacility of colony forming and T-AOC in HSCs were decreased. ASP could significantly decrease the percentage of SA-beta-Gal positive cells, the ratio of G1 stages and the production of ROS in HSCs, and downregulate the expression of p16 in mRNA level in HSCs contrast to aging group without ASP treatment. In addition, ASP could remarkably increase T-AOC and the capacility of colony forming in HSCs compared with aging group without ASP treatment., Conclusion: X-ray (3.0 Gy/8 F) could induce mice HSCs aging. ASP could delay senescence HSCs aging which maybe partly ascribed to the inhibition of oxidative damage and the downregulation of p16 mRNA expression.