The Expression And Correlation Studies Of Bcl-2and C-kit In The Thin Endometrium Of Human During The Late Proliferative Phase

BackgroundThe two factors which closely related to the pregnancy rate in assisted reproductive technology (ART) are embryo quality and endometrial receptivity. Though ART technology in recent years development rapidly and the embryo laboratory technology has been greatly improved, the success of in vitro fertilization-embryo transfer (IVF-ET) rate is still hovering at40～50%.This phenomenon prompted a growing number of scholars have begun to pay attention to-endometrial receptivity. Most studies have shown that endometrial thickness and embryo implantation rate has a significant correlation. Endometrial thickness can reflect endometrial function and predict endometrial receptive ability. A certain thickness of the endometrium is a necessary condition for embryo implantation and a fertility-determining factor. At present, thin endometrium has no clear diagnostic criteria. But most of the literatures defined the mid-luteal endometrial thickness who<7mm as thin endometrium. A thin endometrium has been well recognized as a critical factor in implantation failure.Patients with thin endometrium are common in IVF cycles. A thin endometrium is associated with low implantation rates. So thin endometrium is considered to be one of the key factors for embryo implantation failure.Women with thin endometrium usually have to be frozen embryos and canceled cycles repeatedly. Uterine blood flow is an important factor controlling endometrial growth. Estrogen, low-dose aspirin and sildenafil were given to patients with thin endometrium to increase their endometrial thickness. But the efficacy is poor, and at the same time there are some side effects. Therefore, there is a lot of controversy on the treatment of thin endometrium. Some scholars even do not recommend these drugs.There are some clinical studies found that endometrial thickness is independent with estrogen concentration in IVF circles. Others found blood flow of thin endometrium have no difference with the normal group. So maybe there are other factors that affect endometrial cell proliferation.Recently studies have found that apoptosis is present in endometrium. They put forward the view that apoptosis regulate the cyclical changes of endometrium Imbalance of cell proliferation and apoptosis may cause endometrial disease. They found Bcl-2and c-kit are associated with ovarian hormone levels and play an important role in endometrial cell proliferation and apoptosis. At the same time, these factors are markers of endometrial stem cells. They can reflect the proliferative capacity of endometrium stem cells to a certain extent. These studies proposed a new theoretical guidance for the study of thin endometrium pathogenesis and clinical treatment. But there are few researches to study the thin endometrium from the view of cell proliferation and apoptosis.This experiment studied the expression of Bcl-2and c-kit and their relations in the patients with thin endometrium (endometrial thickness<7mm) who will to accept therapy in Zhengzhou University Center for Reproductive Medicine of the First Affiliated Hospital. The purpose of this experiment is to provide a theoretical basis for research to improve endometrial thickness, endometrial receptivity and pregnancy rate in assisted reproductive technology. ObjectiveTo investigate the expression of Bcl-2and c-kit in the thin endometrium of the late proliferative phase. Explore the relationship between them.Providing a theoretical basis to improve the endometrial thickness, endometrial receptivity and pregnancy rate of assisted reproductive technology.Materials and methodsSelect40patients who had prepared to accept treatment for infertility during September2012to January2013in the first affiliated hospital of Zhengzhou university reproductive center. Patients were divided into two groups according to their endometrial thickness. Control group:normal thickness endometrium (endometrial thickness>8mm,<14mm,n=20); experimental group:thin endometrium (endometrial thickness<7mm, n=20). All patients with normal menstrual cycles (28-35days); Nearly three months did not take hormone therapy; Normal hysteroscopy; Endometrial tissue was taken in late Proliferation phase; Saline irrigation portion of organizations then invested it into95%alcohol for pathological examination. The remaining tissue was divided into two parts. One was to do paraffin sections, HE staining. Immunohistochemical technique was used to examine the expression of c-kit and Bcl-2in the endometrium. The other part was to do Western blot analysis. The data were statistically analyzed using SPSS12.0statistical software.Results1. Bcl-2positive cells were brown homogeneous shape and expressed in endometrial glands and stroma in the late proliferation phase. Mainly in the glands, located in the cytoplasm. Immunohistochemistry and Western blot results show that Bcl-2was detected in normal endometrium and thin endometrium. The relative expression of Bcl-2in the endometrium of the experimental group was significantly lower than the control group. The difference was statistically significant (P<0.05).2. C-kit positive cells were brown or brownish yellow and expressed in the cell membrane and cytoplasm of the endometrial glands. C-kit exists mainly in the membrane, and expressed in a small amount of cytoplasm. Punctuates expression were seen in endometrial stromal cells. Immunohistochemistry and Western blot results show that c-kit was detected in normal endometrium and thin endometrium. The experimental group c-kit expression in endometrial significantly lower than the control group, the difference was statistically significant (P<0.05).3. C-kit expression was positively correlated with Bcl-2in the groups of normal thickness endometrium and thin endometrium.(Respectively, r=0.883, P=0.000; r=0.906, P=0.000).Conclusion1. Thin endometrium group Bcl-2expression was significantly decreased which shows that the ability to inhibit apoptosis was decreased in thin endometrium. Bcl-2may play a key role in the development and progression of thin endometrium.2. C-kit expression was significantly decreased in thin endometrium group which shows that the ability of cell proliferation was reduced in thin endometrium. C-kit may play a key role in the development and progression of thin endometrium.3. C-kit expression was positively correlated with Bcl-2in the groups of normal endometrium and thin endometrium which means that there may be a correlation between the two factors. Together, they affect the proliferation and apoptosis of endometrial cells involved in the occurrence of thin endometrium.