Background. One of the fundamental pathogenesis of endometriosis to grow and develop is to carry out a cellular invasion of the surrounding tissue where it attaches. The invasion process of endometriotic focus is linked with the activity of matrix metalloproteinases-2 (MMP-2) and tissue inhibitors of metalloproteinases-2 (TIMP-2). In this study, we used endometrioma tissue to be implanted in chick chorioallantoic membrane (CAM) as a medium culture model to reconstruct and evaluate the invasion process of endometriosis. Then the MMP-2, TIMP-2 and invasion pattern can be invitro observed.
Methods. Endometrioma tissue fragments were taken from ovarian endometrioma patients, reproductive age, no medication and no malignancy who underwent laparoscopic surgery. Sample research was taken in consecutive and non-probability sampling. The tissue fragments were divided into 4-8 strips, each dimension of 2 x 2 mm2. Two strips were assessed for the activity of MMP-2. Two remaining strips were transplanted onto the CAM. After incubation for five days, the transplanted tissues were harvested for assessment of MMP-2 by gelatin zymography, TIMP-2 by western blot and histological assessment by hematoxylin-eosin staining. The assessment was carried out by two qualified biologists as an observer.
Result. Twenty-four fragments of endometrioma have been collected from 24 endometrioma patients who underwent laparoscopy surgery. The average age was 31±5 years, the BMI was 22±3 kg/m2, the duration of infertility was 58 ± 3 months, and r-ASRM was 67±35. In CAM of transplanted endometriomas tissue, MMP-2 activity was positively correlated with TIMP-2 in a moderate relationship (rô = 0.56, p-value < 0.05), very weak positive correlation with invasion level (rô = 0.08, p-value >0.05). TIMP-2 expression was negatively correlated with invasion level in a strong relationship (rô = -0.35, p-value <0.05). The ratio between MMP-2/TIMP-2 was positively correlated with invasion level in a very strong relationship (rô = 0.72, p-value < 0.05). ICC (intraclass correlation coefficient) value was 0.96, and p-value= 0.01, CI 95%. It shows that there was high reliability between observers.
Conclusion. The invasion level of endometrioma transplanted onto CAM was determined by the balance between MMP-2 and TIMP-2.