反复着床失败（RIF）严重影响着试管婴儿的成功率，给不孕夫妇带来高昂的治疗费用及沉重的心理负担。我们前期研究发现宫腔注射自体外周血单个核细胞（PBMC）可以提高RIF患者的妊娠率和活产率，此方法与传统皮下注射丈夫或第三者淋巴细胞的方法相比具有操作简单、安全简便、无变态反应等优点，但其内在机理尚待阐明。近年来研究显示Th17/Treg细胞分化及平衡与妊娠期母胎免疫耐受密切关联，我们的预实验结果提示：PBMC宫腔注射可以增加胎盘组织中Treg细胞数目及Foxp3，PD-L1mRNA的表达。为此，我们提出假说: 宫腔注射PBMC通过调节母胎界面的Th17/Treg细胞免疫平衡，利于胚胎着床。为了验证这一假说，我们通过胚胎着床障碍模型初步探讨宫腔注射PBMC对胚胎着床的影响及其Th17/Treg免疫平衡机制研究。为反复着床失败及复发性流产等免疫相关疾病的防治提供新的思路。

Repeated implantation failure (RIF) has a serious impact on the success rate of IVF, which brings high cost and heavy psychological burden to infertile couples. Our previous studies have found that intrauterine injection of autologous peripheral blood mononuclear cells (PBMC) could increase pregnancy rate and livebirth rate in RIF patients, this method was more simple, safe, easy and no allergy compared to the method of subcutaneous husband or other's lymphocyte, but its mechanism remains to be further explored. Recent studies have shown that Th17/Treg cells immune balance was closely related to the maternal fetal immune tolerance during pregnancy, and our results indicated that: intrauterine injection of PBMC could increase the number of Treg cells and the mRNA expression of Foxp3 and PD-L1 in placental tissue. Therefore, we hypothesized that: intrauterine injection of PBMC regulates Th17/Treg cells immune balance in the maternal-fetal interface to promote embryo implantation. To test this hypothesis, we implore the effect of intrauterine injection of PBMC on embryo implantation and its mechanism of Th17/Treg cell immune balance in mice of embryo implantation dysfunctional. It provides new ideas for the immune-related diseases’ prevention and treatment such as RIF and recurrent spontaneous abortion.