NOTCH1- and CD117-Positive Stem Cells in Human Endometriosis and Adenomyosis Lesions

Adenomyosis and endometriosis are distinct gynecological disorders characterized by ectopic growth of endometrial tissue. Their etiology remains unclear, but stem cells have been implicated in both. The aim of this study was to investigate and compare the quantity of NOTCH1+ and CD117+ stem cells in endometriosis and adenomyosis lesions. Immunohistochemical staining of ectopic endometrium biopsies using antibodies against NOTCH1 and CD117 was performed. The quantity and spatial distribution of endometrial stromal cells positive for these markers were determined and compared between endometriosis and adenomyosis lesions. Additionally, their quantities were compared between endometriosis lesion types. Mann-Whitney U test showed that the median percentages of both NOTCH1+ and CD117+ cells in the endometriosis lesions were significantly higher than those in the adenomyosis lesions (2.26% vs. 0.13%, p = 0.002 and 0.44% vs. 0.26%, p = 0.016, respectively). Spearman's test showed a positive correlation between NOTCH1+ and CD117+ cells in endometriosis lesions (R = 0.45, p = 0.027) but no significant correlation in adenomyosis lesions (R = -0.11, p = 0.69). The quantity of both stem cell types was highest in extragenital endometriotic lesions. Unlike adenomyosis, endometriosis lesions are associated with higher quantities of NOTCH1+ and CD117+ stem cells and a coordinated increase in their number. These findings support the distinct origin of the two conditions.