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This paper presents an approach to simplify building polygons with blurred outline. Definitions of main direction and feature edges that control overall structure of building polygon are proposed to maintain its regular shape. Firstly, the polygon is squared based on the main direction which is calculated by statistical weighting method. Secondly, the feature edges are grouped and abstracted into several types of local structures with corresponding reconstruction rules after they are found in the right-angled building polygon according to the definition of feature edges. Finally, the spatial relationship of the feature edges in the structure is distinguished to select the right reconstruction rule to simplify polygon. The experiments under real data shows that the method is able to restore the rectangularity of the building polygon effectively, maintain the area and the overall shape structure, and hold high reliability and practicability.

ObjectiveTo explore the effect of estradiol on human bone marrow mesenchymal stem cells (BMSCs) and the therapeutic effect of estradiol-pretreated BMSCs on liver cirrhosis in mice. MethodsThird-passage BMSCs were divided into control (untreated with estradiol) and experimental groups (treated with different concentrations of estradiol); the effect of estradiol on the proliferative activity of BMSCs was measured by MTT assay. Apoptosis was induced by H2O2 in the control and experimental groups of BMSCs, with normal BMSCs as the blank group; the effect of estradiol on apoptosis in BMSCs was tested by trypan blue staining and quantitative real-time PCR of caspase-3 mRNA. Forty-six normal male C57BL mice were assigned to control, model, BMSC transplantation, and estradiol-pretreated BMSC transplantation groups. An animal model of liver cirrhosis was established by intraperitoneal injection of CCl4. At 12 weeks after CCl4 injection, estradiol-pretreated and untreated BMSCs were transplanted into mice through the tail vein. At 4 weeks after BMSC transplantation, blood samples were collected for serum alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST) assays. The stage of liver fibrosis was determined by hematoxylin-eosin and Masson staining. Type I collagen (collagen I) expression was analyzed by RT-PCR. Normally distributed categorical data (with homogeneous variances) were analyzed using ANOVA, followed by pairwise comparisons using LSD test; non-normally distributed data (with heterogeneous variances) were analyzed using Mann-Whitney rank-sum test. ResultsAll the experimental groups had higher proliferative activity than the control group (F=730.08, P=0.000). H2O2 promoted apoptosis in BMSCs, with lower apoptosis rate in the experimental groups than in the control group (F=258.34, P=0.000). Caspase-3 mRNA expression wassignificantly different between the control and experimental groups (F=50.29, P=0.000). Additionally, there were significant differences in rats between the model, BMSC transplantation, and estradiol-pretreated BMSC transplantation groups in terms of ALT (P=0.000 for all), AST(P＜0.05 for all), fiber ratio (P＜0.05 for all), and collagen I mRNA expression (P＜0.05 for all). ConclusionEstradiol promotes the proliferation and reduces H2O2-induced apoptosis in BMSCs. BMSCs can improve liver cirrhosis and their therapeutic effect is enhanced by estradiol pretreatment.

Substantial progress has been made in the stem cell therapy for liver fibrosis. However, the therapeutic effect is limited by decreased self-renewal of stem cells during migration. Therefore, to improve the self-renewal of stem cells after transplantation is urgent and essential for the successful application of stem cells in clinical practice. Current studies have shown that sex hormones have an impact on the self-renewal of stem cells. The effects of estrogens and androgens on the self-renewal of various stem cells and the functional differences between the stem cells from persons of different sexes are reviewed. Moreover, the effect of sex hormones on stem cell therapy for liver fibrosis is discussed. It is considered that sex hormones have significant theoretical and clinical values for improving the self-renewal of stem cells and selecting appropriate stem cells in the stem cell therapy for liver fibrosis.