SIRT1/NF-κB信号轴在人参皂苷Rg_1延缓D-半乳糖致衰老模型大鼠造血干/祖细胞衰老过程中的作用

目的探讨SIRT1／NF-κB信号轴在人参皂苷Rgl对抗衰老模型大鼠造血干／祖细胞衰老中的作用。方法6～8周雄性SD大鼠50只，随机分为对照组、模型组、人参皂苷Rgl对照组、人参皂苷Rgl治疗组和人参皂苷Rg，预防组，每组10只。以连续42 d sc D-半乳糖（D-gal）制备衰老动物模型，人参皂苷Rg1各组ip给药不同时间，药物注射完成第2天，免疫磁性分选法分离纯化各组Sca-1^＋造血干／祖细胞（HSC／HPC），衰老相关β-半乳糖苷酶（SA-β-Gal）染色、流式细胞周期分析和造血祖细胞混合集落（CFU-Mix）培养观察人参皂苷Rg1对Sca-1^＋ HSC／HPC抗衰老的生物学作用。荧光定量PCR及Western blotting检测衰老调控分子SIRTl、NF-κB mRNA及蛋白的表达。结果与模型组比较，人参皂苷Rgl治疗组和预防组SA-β-Gal染色阳性率、G0／G1期细胞比例下降，生成CFU-Mix数增高，SIRTlmRNA及蛋白表达上调，NF-κB mRNA及蛋白表达下调；人参皂苷Rgl预防组各指标变化均较人参皂苷Rgl治疗组明显。结论SIRTl／NF-κB信号轴在人参皂苷Rgl对抗D-gal致衰老模型大鼠HSC／HPC衰老过程中发挥重要作用，人参皂苷Rgl具有抗HSC／HPC衰老作用。

Conversion of mononuclear cells from human umbilical cord blood into hepatocyte-like cells

Objective： To evaluate the dltterentlatlon ot human umbilical cord blood ceils into hepatocyte-like cells. Methods： Mononuclear cells （MNCs） derived from human umbilical cord blood were isolated using Ficoll. The experiment was derived into 3 categories： （1） MNCs co-cultured with 50 mg minced liver tissue separated by a trans-well membrane and then collected at 0 h, 24 h, 48 h and 72 h; （2） MNCs cultured along supplemented with 100 ml/L FBS, 100 μ/ml penicillin, 100 μg/ml streptomycin, 4.7 μg/ml linoleic acid, 1×ITS, 10^-4 mol/L L-Ascorbic acid 2-P and a combination of FGF4 （100 ng/ml） and HGF （20 ng/mL）. Cells were then collected at 0 d and 16 d to examine the expression profile of hepatocyte correlating markers; （3） 0.2-0.3 ml of MNCs with a cell density of 2×10^7/ml were transplanted into prepared recipient mice [n=12, injected with 0.4 ml/kg （20%） CCl4 and 150 ng/kg 5-fluorouracil （5-Fu） prior the transplant 24 h and 48 h, respectively] via injection through tail vein. Mice were sacrificed 4 weeks after transplantation. The hepatocyte correlating mRNAs and proteins were determined by RT-PCR, immunohistochemical analysis and immunoflurence technique. Results： （1） After 72 h, a number of glycogen positive stained cells were observed with MNCs co-cultured with damaged mouse liver tissues. The expression of hepatocyte markers, human albumin （ALB）, α-fetal protein （AFP） and human GATA4 mRNA and proteins were detected by RT-PCR and immunohistochemistry as well. For the confirmation, the DNA sequencing of PCR products was performed. In control groups, MNCs co-cuhured with normal mouse hepatocytes or MNCs cultured alone, all markers remained negative. （2） In growth factor supplemented culture system, MNCs developed into larger volume with richer cytoplasm and binucleation after 16 d. Positive expression of ALB, AFP, CK18 and CK19 mRNA were detected with RT-PCR, and ALB positive staining was observed by immunocytochemistry as well. In contrast, MNCs cultured without exogenous growth factors scarcely attached to the culture dish and ALB mRNA was not detected. （3） In transplantation experiment, both of ALB and AFP mRNA were detected by RT-PCR and HSA, PCNA and ALB positive staining were observed in the livers of recipient mice by immunocytochemistry. Conclusion： MNCs from human umbilical cord blood could convert into hepatocyte-like ceils in 3 different ways, indicating their potential use in the clinic applications for the treatment of human liver diseases.

Effects of cannabinoid receptor type 2 on endogenous myocardial regeneration by activating cardiac progenitor cells in mouse infarcted heart

Cannabinoid receptor type 2(CB2)activation is recently reported to promote proliferation of some types of resident stem cells(e.g.,hematopoietic stem/progenitor cell or neural progenitor cell).Resident cardiac progenitor cell(CPC)activation and proliferation are crucial for endogenous cardiac regeneration and cardiac repair after myocardial infarction(MI).This study aims to explore the role and possible mechanisms of CB2receptor activation in enhancing myocardial repair.Our results revealed that CB2receptor agonist AM1241 can significantly increase CPCs by c-kit and Runx1 staining in ischemic myocardium as well as improve cardiomyocyte proliferation.AM1241 also decreased serum levels of MDA,TNF-αand IL-6 after MI.In addition,AM1241 can ameliorate left ventricular ejection fraction and fractional shortening,and reduce fibrosis.Moreover,AM1241 treatment markedly increased p-Akt and HO-1 expression,and promoted Nrf-2 nuclear translocation.However,PI3K inhibitor wortmannin eliminated these cardioprotective roles of AM1241.In conclusion,AM1241 could induce myocardial regeneration and improve cardiac function,which might be associated with PI3K/Akt/Nrf2 signaling pathway activation.Our findings may provide a promising strategy for cardiac endogenous regeneration after MI.

CAPE promotes the expansion of human umbilical cord blood-derived hematopoietic stem and progenitor cells in vitro

Due to the low number of collectable stem cells from single umbilical cord blood(UCB)unit,their initial uses were limited to pediatric therapies.Clinical applications of UCB hematopoietic stem and progenitor cells(HSPCs)would become feasible if there were a culture method that can effectively expand HSPCs while maintaining their self-renewal capacity.In recent years,numerous attempts have been made to expand human UCB HSPCs in vitro.In this study,we report that caffeic acid phenethyl ester(CAPE),a small molecule from honeybee extract,can promote in vitro expansion of HSPCs.Treatment with CAPE increased the percentage of HSPCs in cultured mononuclear cells.Importantly,culture of CD34+HSPCs with CAPE resulted in a significant increase in total colony-forming units and high proliferative potential colony-forming units.Burst-forming unit-erythroid was the mostly affected colony type,which increased more than 3.7-fold in 1μg mL 1CAPE treatment group when compared to the controls.CAPE appears to induce HSPC expansion by upregulating the expression of SCF and HIF1-α.Our data suggest that CAPE may become a potent medium supplement for in vitro HSPC expansion.

Multipotent mesenchymal stromal cells are fully permissive for human cytomegalovirus infection

Congenital human cytomegalovirus(HCMV) infection is a leading infectious cause of birth defects.Previous studies have reported birth defects with multiple organ maldevelopment in congenital HCMV-infected neonates. Multipotent mesenchymal stromal cells(MSCs) are a group of stem/progenitor cells that are multi-potent and can self-renew, and they play a vital role in multiorgan formation. Whether MSCs are susceptible to HCMV infection is unclear. In this study, MSCs were isolated from Wharton's jelly of the human umbilical cord and identified by their plastic adherence, surface marker pattern, and differentiation capacity. Then, the MSCs were infected with the HCMV Towne strain, and infection status was assessed via determination of viral entry,replication initiation, viral protein expression, and infectious virion release using western blotting,immunofluorescence assays, and plaque forming assays. The results indicate that the isolated MSCs were fully permissive for HCMV infection and provide a preliminary basis for understanding the pathogenesis of HCMV infection in non-nervous system diseases, including multi-organ malformation during fetal development.