Spatially Mapping the Mechanical and Structural Properties of the Seedling Uterine Fibroid-Myometrium Interface

ABSTRACT Uterine fibroids (leiomyomas) are highly prevalent, noncancerous tumors canonically described as stiff and collagen-dense. Still, the mechanical heterogeneity within uterine fibroids and the alterations that occur at the fibroid–myometrium interface remain poorly understood. This study quantitatively maps the local mechanical, structural, and compositional properties of seedling uterine fibroids ( < 1 cm) at the interface region. Relative to patient-matched myometrial tissues, uterine fibroids exhibited increased stiffness, decreased permeability, increased diffusivity, decreased hydration, greater collagen content, and distinct collagen organization. At the fibroid–myometrium interface, a band of aligned myometrial fibers immediately adjacent to the fibroid was observed, and heterogeneous spatial patterns in elastic modulus and permeability were identified. Ultimately, this study establishes foundational knowledge on the mechanics and structure of seedling uterine fibroids, facilitating future developments of clinically translatable detection tools.