Generation of human/rat xenograft animal model for the study of human donor stem cell behaviors in vivo

AIM: To accurately and realistically elucidate human stem cell behaviors in vivo and the fundamental mechanisms controlling human stem cell fates in vivo, which is urgently required in regenerative medicine and treatments for some human diseases, a surrogate human-rat chimera model was developed.METHODS: Human-rat chimeras were achieved by in utero transplanting low-density mononuclear cells from human umbilical cord blood into the fetal rats at 9-11 d of gestation, and subsequently, a variety of methods, including flow cytometry, PCR as well as immunohistochemical assay, were used to test the human donor contribution in the recipients.RESULTS: Of 29 live-born recipients, 19 had the presence of human CD45+ cells in peripheral blood (PB) detected by ? ow cytometry, while PCR analysis on genomic DNA from 11 different adult tissues showed that 14 selected from ? ow cytometry-positive 19 animals possessed of donor-derived human cell engraftment in multiple tissues (i.e. liver, spleen, thymus, heart, kidney, blood, lung, muscle, gut and skin) examined at the time of tissue collection, as conf irmed by detecting human β2-microglobulin expression using immunohistochemistry.In this xenogeneic system, the engrafted donor-derived human cells persisted in multiple tissues for at least 6 mo after birth. Moreover, transplanted human donor cells underwent site-specifi c differentiation into CK18-positive human cells in chimeric liver and CD45-positive human cells in chimeric spleen and thymus of recipients.CONCLUSION: Taken together, these fi ndings suggest that we successfully developed human-rat chimeras, in which xenogeneic human cells exist up to 6 mo later. This humanized small animal model, which offers an in vivo environment more closely resembling to the situations in human, provides an invaluable and effective approach for in vivo investigating human stem cell behaviors, and further in vivo examining fundamental mechanisms controlling human stem cell fates in the future. The potential for new advances in our better understanding the living biological systems in human provided by investigators in humanized animals will remain promising.

Overexpression of brain-derived neurotrophic factor in the hippocampus protects against post-stroke depression

Post-stroke depression is associated with reduced expression of brain-derived neurotrophic factor （BDNF）. In this study, we evaluated whether BDNF overexpression affects depression-like behavior in a rat model of post-stroke depression. The middle cerebral artery was occluded to produce a model of focal cerebral ischemia. These rats were then subjected to isolation-housing combined with chronic unpredictable mild stress to generate a model of post-stroke depression. A BDNF gene lentiviral vector was injected into the hippocampus. At 7 days after injection, western blot assay and real-time quantitative PCR revealed that BDNF expression in the hippo- campus was increased in depressive rats injected with BDNF lentivirus compared with depressive rats injected with control vector. Furthermore, sucrose solution consumption was higher, and horizontal and vertical movement scores were increased in the open field test in these rats as well. These findings suggest that BDNF overexpression in the hippocampus of post-stroke depressive rats alleviates depression-like behaviors.

Inhibitory effect of emodin and Astragalus polysaccharide on the replication of HBV

AIM: To evaluate the anti-viral effect of emodin plus Astragalus polysaccharide (APS) in hepatitis B virus (HBV) transgenic mice.METHODS: Sixty HBV transgenic mice (HBV TGM) whose weight varied between 18 and 24 g were randomly divided into 3 groups, with 20 mice in each group. Group A was the normal control, where the mice were treated with physiological saline; group B was the positive control where the mice were treated with lamivudine solution (100 mL/kg per day). Group C was the experimental group where the mice were treated with physiological saline containing emodin and APS (57.59 mg/kg per day and 287.95 mg/kg per day, respectively). The mice were treated daily for 3 wk. After 1 wk recovery time, the mice were sacrifi ced and serum as well as liver tissues were collected for ELISA and histological examination.RESULTS: After 21 d treatment, HBV DNA levels in group B and group C significantly declined when compared with group A (P < 0.05). However, a signif icant increase in HBV DNA content was observed in group B, whereas this phenomenon was not observed in group C. A reduction in the contents of HBsAg, HBeAg and HBcAg in the mice from group B and C was observed when compared with group A.CONCLUSION: Emodin and APS have a weak but persistent inhibitory effect on HBV replication in vivo, which may function as a supplementary modality in the treatment of hepatitis B infection.

Effects of Bu-Shen-An-Tai Recipe and Its Two Components on Endometrial Morphology during Peri-implantation in Superovulated Mice

The aim of this study was to investigate the effect of Bu-Shen-An-Tai recipe （BSATR） and its two components （Bushen recipe, and Huoxue recipe） on endometrial morphology during peri-implantation in superovulated mice. Mice were randomly divided into five groups, including the normal （N）, model （M）, Bushen （BS）, Huoxue （HX） and Bu-Shen-An-Tai （BH） groups. The uteri were collected on day 4 of pregnancy, and the endometrium thickness, microvessel density （MVD） and number of pinopodes observed. Compared with the M group, the endometrial thickness in the BS, HX and BH groups was significantly increased and there was a significant difference in endometrial thickness between the BS and the BH groups. The mean MVD was significantly lower in the M group than in the N group, and there was a significant increase in MVD in the BS, HX and BH groups as compared with the M group. Compared with the M group, the pinopode scores in the en- dometrium were significantly increased in the HX and BH groups; and the BS group had significantly higher pinipode scores than the HX and BH groups. In conclusion, the results of the present study demonstrated that the recipes （Bushen, Huoxue and BSATR） could improve the endometrial envi- ronment by regulating the endometrial thickness, MVD and the number of pinopodes at the window of implantation. Moreover, the Huoxue recipe and the BSATR were more efficient than the Bushen recipe, with the BSATR tending to have the most beneficial effects.

Rescue of the albino phenotype by introducing a functional tyrosinase minigene into Kunming albino mice

AIM: To use the tyrosinase minigene as a visual marker to perform microinjection training and improve the techniques related with transgene to greatly elevate the efficiency of gene transfer. METHODS: A mouse tyrosinase minigene, i.e., TyBS, in which the 2.25-kb authentic genomic 5’ non-coding flanking sequence of mouse tyrosinase was fused to a mouse tyrosinase cDNA, was introduced into the fertilized eggs of outbred Kunming albino mice. RESULTS: Of the 11 animals that developed from the injected eggs, two mice (P1 and #8) exhibited pigmented hair (P1) and eyes (P1 and #8), as confirmed by PCR analysis for the tyrosinase minigene integrated into the genome. When founder P1 was bred to Kunming male mouse, six progeny out of 11 offspring inherited the transgene and the pigmented-eye phenotype. CONCLUSION: Taken together, these results suggest that this minigene encodes the active tyrosinase protein and that its 5’ flanking region contains the sequences regulating the expression of mouse tyrosinase gene as expected. We have rescued the albino phenotype by introduction and expression of a functional tyrosinaseminigene in the Kunming albino mouse and the transgene can be passed to subsequent generation. These findings also indicate that TyBS can be a useful visual marker gene in the co-transgenic experiments.

Evaluation of recombinant endostatin in the treatment of atherosclerotic plaques and neovascularization in rabbits

Objective:Atherosclerotic plaques and neovascularization play an important role in the course of coronary atherosclerosis.This study evaluated the effect of recombinant endostatin on experimental atherosclerotic plaques and neovascularization in rabbits.Methods:Eighteen healthy male rabbits were divided into three groups:control group,atherosclerotic model group,and recombinant endostatin treated group.The atherosclerotic model was established via a high-cholesterol diet after balloon catheter injury.The subject weights,serum total cholesterol,creatine kinase-myocardial band fraction(CKMB),and matrix metalloproteinase-2(MMP-2) were measured.Six weeks after treatment,the aortic roots were taken for pathological assay.The thickness ratio of the intima to media was measured by hematoxylin and eosin(HE) staining,and the number of neovessels was measured by immunohistochemistry via monoclonal antibody CD31 staining.Results:The weight,plasma total cholesterol,and CKMB were not significantly different between the atherosclerotic model group and the recombinant endostatin treated group,but much higher than those of the control group(P<0.05).The thickness ratio of the intima to media in the recombinant endostatin treated group was distinctly less than that in the atherosclerotic model group(P<0.05).The number of neovessels decreased dramatically(P<0.05) and the content of MMP-2 decreased slightly without statistical difference(P>0.05) in the recombinant endostatin treated group,compared to the atherosclerotic model group.Conclusions:Recombinant endostatin is able to inhibit the growth of neovascularization in the atherosclerotic plaque and the development of plaque.

A retrospective serological study of severe acute respiratory syndrome cases in Guangdong province,China

Severe acute respiratory syndrome （SARS） is a life threatening, upper respiratory disease. Its cause is a coronavirus, SARS-CoV. Since its emergence in 2003 in China, SARS has affected more than 8000 patients and caused 776 deaths in 26 countries. A reemergence of SARS occurred in Guangdong province, in which the first case was confirmed on January 5, 2004 and three more reported the following month.