Exploring the application value of ultrasound in animal studies of stem cell therapy for intrauterine adhesions

Abstract

Endometrial damage leads to intrauterine adhesions (IUA), significantly impairing endometrial receptivity and fertility. Stem cell therapies, particularly umbilical cord mesenchymal stem cell (UC-MSCs), have shown promise in regenerating damaged endometrium, but prior studies have relied on ex vivo pathological evaluations. Ultrasound, as a non-invasive examination method, provides an important basis for the diagnosis, treatment and prognostic assessment of uterine adhesions in clinical practice. A series of statistical techniques were systematically used in this study, one-way ANOVA test, LSD-t test, Mann Whitney U test, Dunn's t test, and linear regression, with the aim of investigating whether ultrasound can effectively assess the effect of rat IUA model after treatment with IUA. This was an animal study involving 30 female Sprague-Dawley rats randomly divided into three groups: normal (n = 10), IUA model (n = 10), and UC-MSC therapy (n = 10). The study duration was approximately three months, including UC-MSC administration and post-treatment follow-up. IUA was induced in the model and UC-MSC groups by mechanical scraping of the uterine endometrium. Rats in the UC-MSC group received intrauterine infusions of UC-MSCs. Endometrial thickness, morphology, and continuity were evaluated pre- and post-treatment using ultrasound. Histological analysis, including H&E, Masson's staining, and CK immunohistochemistry, was performed after euthanasia. Endometrial thickness significantly increased in the UC-MSC group compared to the model group (0.34 ± 0.06 mm vs. 0.11 ± 0.03 mm, p < 0.05), while fibrosis was significantly reduced (15.11% vs. 28.14%, p < 0.05). The UC-MSC group exhibited improved endometrial morphology and glandular density compared to the model group (p < 0.05). Particularly Ultrasound findings of endometrial thickness, are significantly associated with pathological assessments (r > 0.99, p < 0.0001). This study demonstrates that ultrasound is a reliable, non-invasive tool for monitoring the therapeutic effects of UC-MSCs on endometrial regeneration in vivo.

Keywords: Cell- and Tissue-Based therapy; Endometrium; Fibrosis; Stem cell transplantation; Ultrasonography.

Fig. 1

Flow Cytometry Analysis Results of UC-MSCs.

Fig. 2

Induction of UC-MSCs into Different Tissue Types. UC-MSCs induced into adipose tissue show red staining after Oil Red O staining (a). UC-MSCs induced into osteogenic tissue display red staining after Alizarin Red staining (b). UC-MSCs induced into chondrogenic tissue exhibit blue staining after Alcian Blue staining (c). All images are captured at a magnification of ×400. Scale bar: 50 μm.

Fig. 3

H&E Staining of Endometrial Samples. Endometrium of the normal group (a). Endometrium of the model group (b). Endometrium of the UC-MSCs group(3c). All images are captured at a magnification of ×400. Scale bar: 50 μm.

Fig. 4

Masson Staining of Endometrial Samples. Endometrium of the normal group (a), model group (b) and the UC-MSCs group (c). All images are captured at a magnification of ×400. Scale bar: 50 μm.

Fig. 5

CK Staining of Endometrial Samples. Endometrium of the normal group (a), model group (b) and the UC-MSCs group (c). All images are captured at a magnification of ×400. Scale bar: 50 μm.

Fig. 6

Transabdominal ultrasound with the sagittal images demonstrating. Ultrasound image of the normal endometrium in a 14-week-old rat prior to pregnancy (a) and ultrasound images of the same rat during early, mid, and late stages of pregnancy, respectively (b, c, d). Annotations: GS (Gestational sac), SK (Skull), SP (Spine), AD (Abdomen), UC (Umbilical Cord).

Fig. 7

Transabdominal ultrasound with the sagittal images demonstrating. Ultrasound image of the endometrium after modeling in the same rat (a) and clinical pathological H&E staining image following dissection (b). The pathological image is captured at a magnification of ×400. Scale bar: 50 μm.

Fig. 8

Transabdominal ultrasound with the sagittal images demonstrating. Ultrasound image of the endometrium after modeling in the same rat (a) and ultrasound image of the endometrium after treatment with UC-MSCs (b). Endometrium (thin arrow), Uterine cavity effusion (thick arrow).

Fig. 9

The Promoting Effect of UC-MSCs Treatment on H&E Stained Glands. ***P < 0.001; **P < 0.01; compared to the model group; n = 10.

Fig. 10

The Inhibitory Effect of UC-MSCs Treatment on Masson Stained Fibrosis. ***P < 0.001; **P < 0.01; compared to the model group; n = 10.

Fig. 11

The Promoting Effect of UC-MSCs Treatment on Average Optical Density of CK Staining. ***P < 0.001; **P < 0.01; compared to the model group; n = 10.

Fig. 12

Correlation Analysis between Ultrasound Measurements and Clinical Pathological Measurements of H&E Stained Endometrial Thickness.

Fig. 13

Difference Analysis between Ultrasound Measurements and Clinical Pathological Measurements of H&E Stained Endometrial Thickness.