Development of an experimental model of endometrial pathology (Asherman’s syndrome)

Abstract

Introduction. One of the most challenging problems faced in gynecology is Asherman’s syndrome (AS), characterized by the formation of intrauterine adhesions, partial or complete obliteration of the uterine cavity with scar tissue, and the loss of the functional layer of the endometrium following intrauterine interventions. Treatments for AS are not always effective. This indicates a need to search and evaluate the effectiveness of new approaches to the prevention of fibrosis and stimulation of endometrial regeneration. According to ethical principles, this is possible only when simulating AS on laboratory animals. The aim of the work is to develop an etiologically adequate model of AS in Sprague Dawley rats. Materials and methods. We simulated AS in 18 female Sprague Dawley rats that were divided into 3 groups (6 rats in each). Operations were performed in the estrus phase. We made longitudinal incision of the right uterine horns, and the endometrium was scraped out to the inner layer of the myometrium with the scalpel. Groups 1 and 2 underwent only endometrial scraping. In group 3 abdominal cavities were opened on day 7 after curettage and intrauterine adhesions were destroyed with a needle inserted into the horn. Then, the standard procedure for suturing surgical wound was performed. The animals were removed from the experiment on days 7 (group 1) and 15 (groups 2 and 3) after the surgery with an overdose of ether anesthesia. The tissue samples of the operated and non-operated uterine horns were fixed with 10% buffered formalin and embedded in paraffin; the sections were stained with hematoxylin and eosin. Results. Macroscopic examination on day 7 after the surgery showed that all females had a compaction and contraction of the operated area of the uterine horn and uterine cavity fluid. On day 15, fluid collection was more pronounced. After the destruction of the uterine adhesions in rats from group 3, there was no fluid collection or it was less voluminous than in females of other groups. Histological examination showed that on days 7 and 15 after endometrial curettage, the uterine cavity and the luminal epithelium covering it were absent due to complete replacement by connective tissue. Uterine glands were not detected or were individual. On day 7 after the destruction of the adhesions and on day 15 after endometrial scraping the subjects developed a small stenosed uterine cavity lined with luminal epithelium or a larger uterine cavity containing single or multiple adhesions covered with epithelium. The number of glands was significantly smaller than in the non-operated horn. Conclusion. To simulate Asherman’s syndrome, female Sprague Dawley rats in the estrus phase were scraped out of the endometrial layer of the right uterine horn. On days 7 and 15 after surgery, the uterine cavity and luminal epithelium were absent due to complete replacement with connective tissue, which proves the formation of intrauterine adhesions and the adequacy of the obtained model. A significant difference of the original model was the destruction of the adhesions on day 7 after endometrial damage to remove excess fluid in the uterine cavity and restore uterine patency, which led to the formation of the uterine cavity and re-epithelialization on day 15. The developed model of Asherman’s syndrome can be used to develop new approaches to the prevention of adhesive process and the restoration of endometrial structure and functionality. Keywords: Asherman’s syndrome, experimental model, rat uterus, endometrial curettage, intrauterine adhesions