Comparing the Characteristics of Amniotic Membrane-, Endometrium-, and Urinary-Derived ECMs and Their Effects on Endometrial Regeneration in a Rat Uterine Injury Model

The application of tissue engineering strategies for uterine regeneration

Uterine injuries, particularly damages to endometrium, are usually associated with abnormal menstruation, recurrent miscarriage, pregnancy complications, and infertility. Tissue engineering using cell-based, biomolecule-based, or biomaterial and scaffold-based strategies has emerged as a novel and promising approach for uterine regeneration. Stem cells, biomolecules, and porous scaffolds used alone or, very often, used in combination as a more effective treatment means have shown great potential in promoting uterine regeneration. The reported preclinical studies have indicated that appropriate tissue engineering strategies could safely and effectively reconstruct not only endometrium but also partial or even the whole uterine structure. However, the progress in the uterine regeneration area is slow in comparison to that of regenerating many other body tissues and hence it still remains a great challenge to apply uterine tissue engineering for clinical applications. In this review, conventional treatments for uterine-related diseases are briefly reviewed and discussed first. Subsequently, tissue engineering strategies (cell-based, biomolecule-based, biomaterial and scaffold-based, or their combinations) for uterine repair in preclinical studies and clinical trials are presented and analyzed. Finally, the challenges and perspectives in uterine regeneration are pointed and discussed. Despite various limitations and obstacles, the tissue engineering approach is viable and holds high promise for uterine regeneration.

Bioengineering approaches for the endometrial research and application

The endometrium undergoes a series of precise monthly changes under the regulation of dynamic levels of ovarian hormones that are characterized by repeated shedding and subsequent regeneration without scarring. This provides the potential for wound healing during endometrial injuries. Bioengineering materials highlight the faithful replication of constitutive cells and the extracellular matrix that simulates the physical and biomechanical properties of the endometrium to a larger extent. Significant progress has been made in this field, and functional endometrial tissue bioengineering allows an in-depth investigation of regulatory factors for endometrial and myometrial defects in vitro and provides highly therapeutic methods to alleviate obstetric and gynecological complications. However, much remains to be learned about the latest progress in the application of bioengineering technologies to the human endometrium. Here, we summarize the existing developments in biomaterials and bioengineering models for endometrial regeneration and improving the female reproductive potential.

Animal models of the placenta accreta spectrum: current status and further perspectives

Placenta accreta spectrum disorder (PAS) is a kind of disease of placentation defined as abnormal trophoblast invasion of part or all of the placenta into the myometrium, even penetrating the uterus. Decidual deficiency, abnormal vascular remodeling in the maternal-fetal interface, and excessive invasion by extravillous trophoblast (EVT) cells contribute to its onset. However, the mechanisms and signaling pathways underlying such phenotypes are not fully understood, partly due to the lack of suitable experimental animal models. Appropriate animal models will facilitate the comprehensive and systematic elucidation of the pathogenesis of PAS. Due to the remarkably similar functional placental villous units and hemochorial placentation to humans, the current animal models of PAS are based on mice. There are various mouse models induced by uterine surgery to simulate different phenotypes of PAS, such as excessive invasion of EVT or immune disturbance at the maternal-fetal interface, which could define the pathological mechanism of PAS from the perspective of the "soil." Additionally, genetically modified mouse models could be used to study PAS, which is helpful to exploring the pathogenesis of PAS from the perspectives of both "soil" and "seed," respectively. This review details early placental development in mice, with a focus on the approaches of PAS modeling. Additionally, the strengths, limitations and the applicability of each strategy and further perspectives are summarized to provide the theoretical foundation for researchers to select appropriate animal models for various research purposes. This will help better determine the pathogenesis of PAS and even promote possible therapy.