International Journal of

Introduction
 
Although both subclinical and clinical pregnancy losses occur, the majority of failed IVF-ET cycles exhibit lack of implantation. Implantation failure may occur repeatedly. These patients are challenges for the infertility specialist (1, 2). Endometrial function and receptive endometrium are essential for implantation (3, 4). Repeated implantation failure (RIF) was defined as pregnancy failure after 2-6 times with at least 10 high quality embryos transferred into the uterus (5).
About 40% of IVF cycles will be failed following one IVF cycle. IVF Failure is caused by either failure in early stage of implantation or early abortion. Major causes of IVF failure may be related to embryo quality and implantation failure (6-11). Granulocyte colony stimulating factor (GCSF) is synthesized in the reproductive tract naturally. GCSF stimulate neutrophilic granulocyte proliferation and differentiation, which act on macrophages of decidual cells, and finally affect implantation (12-14).
The recruitment of dendritic cells, Th-2 cytokine secretion and activation of T regulatory cells are the others immune effects of GCSF. The cytokine increase the proportion of embryos that develop to the blastocyst stage from 30-76%. Also GCSF supplemented to the embryo culture medium improves implantation rate. Combination of follicular GCSF and IL-15 is an effective method to define oocyte component for successful conception in IVF/ICSI cycles (15-17).
Most important role of GCSF is improving blastocyst development, aid to embryo implantation and improving devolvement of fetus and placenta (15, 16). GCSF can be effective treatment in patient with history of implantation failure and can improve endometrium growth. Also GCSF may increase pregnancy rate especially in women with thin endometrium (18, 19). GCSF is a glycoprotein that stimulates cytokine growth factor inducing immune system. GCSF stimulates the proliferation and differentiation of endometrial cells by CAMP increase in stromal cell through paracrine and autocrine 
Table I. demographic characteristics of participants

*Data are presented as mean±SD.            # Student t-test                Basal FSH level (day 3 FSH) (IU/L)*# 

Table II. Cycle characteristics of participants

Data presented as mean±SD. (n=45)                            $ Data presented as n (%)                                                # Data presented as mean±SD.
* Comparison was done by Independent t-test.       ** The comparison was done by c².



Figure 1. Consort flow chart


Discussion
 
The endometrial receptivity and thickness play essential role in implantation phase (18, 20, 21). Based on our study, clinical pregnancy rate was improved by GCSF intrauterine infusion on ovarian puncture day. similar to previous studies that indicated G-CSF administration may have beneficial effect on clinical pregnancy outcome after ART our findings showed that intrauterine infusion significantly improves the clinical pregnancy rate (22). One of the first studies of GCSF was a prospective cohort study on 4 patients to evaluate the effect of GCSF on thin endometrium. These cohort findings represented GCSF is a new treatment of thin endometrium (18).
After the pilot study Barad et al studied the GCSF effect on endometrium and clinical pregnancy rate in a parallel double blinded placebo-controlled clinical trial with 141 consecutive, unselected, consenting women with no history of renal disease, sickle cell disease, or malignancy who were undergoing IVF, in this study GCSF does not improve endometrial thickness or pregnancy rate (23). The other study on 37 patients with thin endometrium demonstrated that infusion of GCSF improves the endometrial thickness (24). Eftekhar et al also in an interventional study on 67 infertile women showed although GCSF did not improve endometrial thickness but significantly increased the pregnancy rate in women with thin endometrium (20). But most of the previous studies reported the GCSF role on endometrial thickness improvement (24, 25). The useful role of GCSF on implantation was overlooked.
In spite of lesser follicles and metaphase II oocytes in GCSF group (statistics significance), implantation and pregnancy rate were higher than control. Our study findings showed that clinical and chemical pregnancy rate were improved by GCSF intrauterine infusion on the day of ovarian puncture. The point of GCSF effect may be endometrial-embryo interaction which should be added to many positive influences of GCSF such as effect on ovarian function, granulose cell function, human decidual macrophages, ovulation and reduction of unexplained repeated abortion (14, 16). The most important limitation of the rare studies about the role of GCSF on implantation was limited sample size but in our study this limitation was satisfied. Although the mechanism of intrauterine infusion of GCSF is not found by details but since intrauterine GCSF decreases CD16 and CD56 and also increases LIF significantly, so the chances of getting pregnant will be improved (23). As noted in some studies exogenous GCSF intrauterine infusion as chemical and mechanical stimuli can improve the implantation and pregnancy outcomes. The considered mechanism is that GCSF may induce secretion of endogenous cytokines activating the endocrine pathway (14, 20, 23-25). Although our sample size was adequate but there were no blinding in our study.
 
Conclusion
 
As a conclusion intrauterine infusion of GCSF in infertile women with history of implantation failure is an effective treatment and can improve the pregnancy outcome.
 
Acknowledgements
 
This study was supported by Yazd research and clinical center for infertility, Shahid Sadoughi University of medical sciences. We want to thank all of study participants and infertility clinic staff.
 
Conflict of Interest
 
The authors declare that there was no conflict of interests regarding the publication of this article.