Spatiotemporal mapping of ex vivo myometrial contractions in adenomyosis

Objective: Uterine dyscontractility plays a major role in pain sensation, infertility, and adenomyosis pathogenesis. In vivo, contractility occurs in the inner myometrium and junctional zone, which is thickened in adenomyosis. We examined whether the junctional zone presents particular contractile features ex vivo by measuring contractility and oxytocin response in full-thickness serosa-to-endometrium myometrial slices retrieved from control and adenomyosis patients. Design: Prospective ex vivo case-control study. Subjects: Premenopausal women following hysterectomy: adenomyosis (n = 16) and controls (n = 12). Contractility: 57 strips (11 vs 8 patients), immunofluorescence: 10 vs 9 patients. Main Outcome Measures: We resorted to spatiotemporal mapping, time-lapse video-based techniques used in the field of gastroenterology. We measured contraction frequency, amplitude, duration, velocity, site of origin, and propagation direction along the serosa-to-endometrium axis, before and after oxytocin. We measured oxytocin receptor density along the serosa-to-endometrium axis by immunofluorescence and machine learning-assisted segmentation. Results: Ex vivo contractile waves propagated throughout the outer and inner myometrium, with similar amplitude and frequency. Contraction frequency, amplitude, duration, and velocity did not differ between control and adenomyosis uteri. Oxytocin increased contraction frequency and velocity and systematically caused contractile waves to originate at the inner myometrium in both groups. In both groups, oxytocin receptor density was highest in the inner myometrium. Adenomyosis patients had a 1.8-fold higher oxytocin receptor density, but a smaller oxytocin-induced increase in contraction frequency. Conclusion: We provide the first ex vivo spatiotemporal time-lapse analysis of myometrial contractions. The whole myometrium contracts ex vivo, not just the inner part (junctional zone). This uniform myogenic motility is presumably inhibited neurally in vivo in the outer myometrium. Ex vivo adenomyosis basal contractility was similar to that of controls. Adenomyotic myometrium overexpressed oxytocin receptors compared to controls, but this did not translate into a stronger contractile response to oxytocin. In both groups, oxytocin caused contractile waves to originate at and propagate from the sub-endometrial myometrium, where receptor density is higher. This demonstrates that contractile wave direction can be controlled hormonally.