Modelling the impact of decidual senescence on embryo implantation in human endometrial assembloids

Abstract

Decidual remodelling of midluteal endometrium leads to a short implantation window after which the uterine mucosa either breaks down or is transformed into a robust matrix that accommodates the placenta throughout pregnancy. To gain insights into the underlying mechanisms, we established and characterised endometrial assembloids, consisting of gland organoids and primary stromal cells. Single-cell transcriptomics revealed that decidualized assembloids closely resemble midluteal endometrium, harbouring differentiated and senescent subpopulations in both glands and stroma. We show that acute senescence in glandular epithelium drives secretion of multiple canonical implantation factors, whereas in the stroma it calibrates the emergence of anti-inflammatory decidual cells and pro-inflammatory senescent decidual cells. Pharmacological inhibition of stress responses in pre-decidual cells accelerated decidualization by inhibiting senescence and mesenchymal-epithelial transition, processes involved in endometrial breakdown and regeneration, respectively. Accelerated decidualization resulted in entrapment of co-cultured human blastocysts in a largely static decidual matrix. By contrast, the presence of senescent decidual cells created a dynamic implantation environment, enabling embryo expansion and attachment, although their persistence led to gradual disintegration of assembloids. Our findings demonstrate that senescence controls endometrial fate decisions at implantation and highlight how endometrial assembloids may accelerate the discovery of new treatments to prevent reproductive failure.

Miscarriage syndrome: Linking early pregnancy loss to obstetric and age-related disorders

“… 20 Senescent endometrial fibroblasts secrete an abundance of extracellular matrix proteins and proteinases, chemokines, and inflammatory mediators, which create a permissive implantation environment. 21 Although initially few in number, prolonged SASP production induces secondary senescence in neighbouring decidual cells, tissue inflammation, influx of neutrophils and menstrual breakdown. 16 , 19 Upon successful embryo implantation, progesterone-dependent decidual cells are maintained and counteract the endometrial propensity for self-destruction by secreting interleukin-15 and other factors that instruct uterine NK cells to eliminate senescent fibroblasts.…”

Organoids to model the endometrium: implantation and beyond

“…The assembloids represent a more physiological model of the native organ or tissue, and therefore should provide a more faithful model for testing drug responses and mimicking disease phenotypes. Recently, we have reported the establishment of endometrial assembloids whereby the gland organoid model was modified to incorporate stromal cells (Rawlings et al, 2021). Gland organoids were expanded from primary epithelial cells while in parallel the stromal fraction was propagated by standard monolayer culture (Figure 4).…”

“…Recently, we have reported the establishment of endometrial assembloids whereby the gland organoid model was modified to incorporate stromal cells ( Rawlings et al 2021 ). Gland organoids were expanded from primary epithelial cells while in parallel the stromal fraction was propagated by standard monolayer culture ( Fig.…”

“…In this model, gland organoid formation was unperturbed by stromal co-culture, and assembloids resemble the architecture of native endometrium more closely than the gland organoids alone. The addition of stromal cells should abrogate the need for many components of the complex medium of growth factors and inhibitors to maintain secretory gland organoids, and indeed a minimal differentiation medium supported robust glandular differentiation in the assembloid model ( Rawlings et al 2021 ). Based on single-cell transcriptomic analysis, decidualised assembloids closely resemble the mid-secretory endometrium, containing several subpopulations of both stromal and epithelial cells, including senescent stromal and epithelial cells, which secrete many canonical implantation factors.…”

Preparing for implantation

“…Indeed, certain research groups have established ways to grow epithelial cells in three dimensions, while others have created organoids that comprise both epithelial and stromal cells ( Wiwatpanit et al, 2020 ; Cheung et al, 2021 ; Boretto et al, 2017 ; Turco et al, 2017 ). Now, in eLife, Jan Brosens and colleagues – including Thomas Rawlings as first author – report a new laboratory model of the endometrium that can be used to explore the endometrial changes required for embryos to implant ( Rawlings et al, 2021 ).…”