Qingdong Xie

Malignant transformation potentials of human umbilical cord mesenchymal stem cells both spontaneously and via 3-methycholanthrene induction.

Human umbilical cord mesenchymal stem cells (HUMSCs) are highly proliferative and can be induced to differentiate into advanced derivatives of all three germ layers. Thus, HUMSCs are considered to be a promising source for cell-targeted therapies and tissue engineering. However there are reports on spontaneous transformation of mesenchymal stem cells (MSCs) derived from human bone marrows. The capacity for HUMSCs to undergo malignant transform spontaneously or via induction by chemical carcinogens is presently unknown. Therefore, we isolated HUMSCs from 10 donors and assessed their transformation potential either spontaneously or by treating them with 3-methycholanthrene (3-MCA), a DNA-damaging carcinogen. The malignant transformation of HUMSCs in vitro was evaluated by morphological changes, proliferation rates, ability to enter cell senescence, the telomerase activity, chromosomal abnormality, and the ability to form tumors in vivo. Our studies showed that HUMSCs from all 10 donors ultimately entered senescence and did not undergo spontaneous malignant transformation. However, HUMSCs from two of the 10 donors treated with 3-MCA displayed an increased proliferation rate, failed to enter senescence, and exhibited an altered cell morphology. When these cells (tHUMSCs) were injected into immunodeficient mice, they gave rise to sarcoma-like or poorly differentiated tumors. Moreover, in contrast to HUMSCs, tHUMSCs showed a positive expression of human telomerase reverse transcriptase (hTERT) and did not exhibit a shortening of the relative telomere length during the long-term culture in vitro. Our studies demonstrate that HUMSCs are not susceptible to spontaneous malignant transformation. However, the malignant transformation could be induced by chemical carcinogen 3-MCA.

Effects of Hepatitis B Virus S Protein Exposure on Sperm Membrane Integrity and Functions

Background Hepatitis B is a public health problem worldwide. Viral infection can affect a mans fertility, but only scant information about the influence of hepatitis B virus (HBV) infection on sperm quality is available. The purpose of this study was to investigate the effect of hepatitis B virus S protein (HBs) on human sperm membrane integrity and functions. Methods/Principal Findings Reactive oxygen species (ROS), lipid peroxidation (LP), total antioxidant capacity (TAC) and phosphatidylserine (PS) externalization were determined. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays and flow cytometric analyses were performed. (1) After 3 h incubation with 25 µg/ml of HBs, the average rates of ROS positive cells, annexin V–positive/propidium iodide (PI)-negative cells, Caspases-3,-8,-9 positive cells and TUNEL-positive cells were significantly increased in the test groups as compared to those in the control groups, while TAC level was decreased when compared with the control. The level of malondialdehyde (MDA) in the sperm cells exposed to 50 µg/ml of HBs for 3 h was significantly higher than that in the control (P<0.05–0.01). (2) HBs increased the MDA levels and the numbers of ROS positive cells, annexin V–positive/PI-negative cells, caspases-3, -8, -9 positive cells and TUNEL-positive cells in a dose-dependent manner. (3) HBs monoclonal antibody (MAb) and N-Acetylcysteine (NAC) reduced the number of ROS-positive sperm cells. (4) HBs decreased the TAC levels in sperm cells in a dose-dependent manner. Conclusion HBs exposure could lead to ROS generation, lipid peroxidation, TAC reduction, PS externalization, activation of caspases, and DNA fragmentation, resulting in increased apoptosis of sperm cells and loss of sperm membrane integrity and causing sperm dysfunctions.

Investigation of Recombinant Mouse Sperm Protein Izumo as a Potential Immunocontraceptive Antigen

To determine if the recombinant mouse Izumo (mIzumo) could be used as a potential immunocontraceptive antigen.

ORIGINAL ARTICLE: Investigation of Recombinant Mouse Sperm Protein Izumo as a Potential Immunocontraceptive Antigen

To determine if the recombinant mouse Izumo (mIzumo) could be used as a potential immunocontraceptive antigen.

In vitro and in vivo studies evaluating recombinant plasmid pCXN2-mIzumo as a potential immunocontraceptive antigen.

Problems  Study on feasibility of pCXN2‐mIzumo as a potential immunocontraceptive antigen.

ORIGINAL ARTICLE: In Vitro and In Vivo Studies Evaluating Recombinant Plasmid pCXN2-mIzumo as a Potential Immunocontraceptive Antigen

Problems  Study on feasibility of pCXN2‐mIzumo as a potential immunocontraceptive antigen.

Relationship between LTR Methylation and gag Expression of HIV-1 in Human Spermatozoa and Sperm-Derived Embryos

OBJECTIVE Studying the methylation status of long terminal repeats (LTR) and its relationship to gag expression of HIV-1 in order to explore regulation mechanism of HIV-1 gene expression in vertical transmission from sperm to embryo. METHODS/PRINCIPAL FINDINGS Sperm samples were collected from a healthy donor and seven patients with HIV/AIDS. Zona-free hamster ova were fertilized by donors spermatozoa transfected with pIRES2-EGFP-LTR-gag and patients spermatozoa to obtain zygotes and 2-cell embryos, respectively. Interspecific in vitro fertilization, bisulfite sequencing PCR (BSP), RT-PCR, nested RT-PCR, nested real-time qRT-PCR and 2(-△△Ct) method, indirect immunofluoresence (IF) assay were performed. For donors samples, the methylation rates of HIV-1 LTR were 0.56%, 1.67%, 0.56%, 0.56% in plasmid, spermatozoa, zygotes and 2-cell embryos, respectively while spermatozoa were transfected with unmethylated plasmid, and were 95.0%, 84.44%, 3.3%, 1.67% while transfected with methylated plasmid. The positive bands for HIV-1 gag cDNA were detected in spermatozoa and 2-cell embryos. The positive signals for HIV-1 p24 Gag protein were detected in 2-cell embryos but not in spermatozoa. For patients samples, methylation rates of HIV-1 LTR were different in spermatozoa among patients. After fertilization, CpG sites in HIV-1 LTR were highly demethylated in zygotes and 2-cell embryos. The gag transcription levels increased with decreasing of methylation rates of HIV-1 LTR, which showed a strong negative correlations between gag transcription levels and methylation rates of HIV-LTR ether in the spermatozoa (r = -0.9877, P<0.0001) or in the sperm-derived 2-cell embryos (r = -0.9092, P = 0.0045). CONCLUSION LTR methylation regulates expression of HIV-1 gag in vertical transmission from sperm to embryo.

A Sensitive and Rapid Assay for Investigating Vertical Transmission of Hepatitis B Virus via Male Germ Line Using EGFP Vector as Reporter

Hepatitis B virus (HBV) constitutes a serious menace to man. DNA recombination and sequencing, interspecific in vitro fertilization, single-embryo PCR and RT-PCR were employed to establish a sensitive and rapid assay for exploring the vertical transmission of viruses via male germ line. Plasmid pIRES2-EGFP-HBs which expressed enhanced green fluorescent protein as reporter for the expression of hepatitis B virus S gene was successfully constructed and confirmed by PCR, EcoR I and Sal I digestion, and DNA sequencing. After exposure to the plasmid, human spermatozoa were used to fertilize with zona-free hamster ova. Two-cell embryos were collected and classified into group A with green fluorescence and group B without green fluorescence under fluorescence microscope. The results showed that HBs DNA positive bands were detected in the embryos with green fluorescence (PCR and RT-PCR) and positive control (PCR) indicating expression of pIRES2-EGFP-HBs, and not observed in the embryos without green fluorescence and negative controls (PCR and RT-PCR) indicating no pIRES2-EGFP-HBs in the cells. The advantages and application foreground of this assay for study on vertical transmission of viruses such as HCV, HIV, HPV, and SARS via germ line were discussed.

Hepatitis B virus s protein enhances sperm apoptosis and reduces sperm fertilizing capacity in vitro.

Objective Studying the impact of Hepatitis B virus S protein (HBs) on early apoptotic events in human spermatozoa and sperm fertilizing capacity. Methodology/Principal Findings Spermatozoa were exposed to HBs (0, 25, 50, 100 µg/ml) for 3 h, and then fluo-4 AM calcium assay, Calcein/Co2+ assay, protein extraction and ELISA, ADP/ATP ratio assay, sperm motility and hyperactivation and sperm-zona pellucida (ZP) binding and ZP-induced acrosome reaction (ZPIAR) tests were performed. The results showed that in the spermatozoa, with increasing concentration of HBs, (1) average cytosolic free Ca2+ concentration ([Ca2+]i) rose; (2) fluorescence intensity of Cal-AM declined; (3) average levels of cytochrome c decreased in mitochondrial fraction and increased in cytosolic fraction; (4) ADP/ATP ratios rose; (5) average rates of total motility and mean hyperactivation declined; (6) average rate of ZPIAR declined. In the above groups the effects of HBs exhibited dose dependency. However, there was no significant difference in the number of sperms bound to ZP between the control and all test groups. Conclusion HBs could induce early events in the apoptotic cascade in human spermatozoa, such as elevation of [Ca2+]i, opening of mitochondrial permeability transition pore (MPTP), release of cytochrome c (cyt c) and increase of ADP/ATP ratio, but exerted a negative impact on sperm fertilizing capacity.

Mutations and CpG islands among hepatitis B virus genotypes in Europe

BackgroundHepatitis B virus (HBV) genotypes have a distinct geographical distribution and influence disease progression and treatment outcomes. The purpose of this study was to investigate the distribution of HBV genotypes in Europe, the impact of mutation of different genotypes on HBV gene abnormalities, the features of CpG islands in each genotype and their potential role in epigenetic regulation.ResultsOf 383 HBV isolates from European patients, HBV genotypes A-G were identified, with the most frequent being genotype D (51.96%) in 12 countries, followed by A (39.16%) in 7 countries, and then E (3.66%), G (2.87%), B (1.57%), F (0.52%) and C (0.26%). A higher rate of mutant isolates were identified in those with genotype D (46.7%) followed by G (45.5%), and mutations were associated with structural and functional abnormalities of HBV genes. Conventional CpG island I was observed in genotypes A, B, C, D and E. Conventional islands II and III were detected in all A-G genotypes. A novel CpG island IV was found in genotypes A, D and E, and island V was only observed in genotype F. The A-G genotypes lacked the novel CpG island VI. “Split” CpG island I in genotypes D and E and “split” island II in genotypes A, D, E, F and G were observed. Two mutant isolates from genotype D and one from E were found to lack both CpG islands I and III.ConclusionsHBV genotypes A-G were identified in European patients. Structural and functional abnormalities of HBV genes were caused by mutations leading to the association of genotypes D and G with increased severity of liver disease. The distribution, length and genetic traits of CpG islands were different between genotypes and their biological and clinical significances warrant further study, which will help us better understand the potential role of CpG islands in epigenetic regulation of the HBV genome.