Advanced Technologies for Studying Microbiome-Female Reproductive Tract Interactions: Organoids, Organoids-on-a-Chip, and Beyond

Abstract

The female reproductive tract (FRT) is home to diverse microbial communities that play a pivotal role in reproductive health and disorders such as infertility, endometriosis, and cervical cancer. To understand the complex host-microbiota interactions within the FRT, models that authentically replicate the FRT's environment, including the interplay between the microbiota, mucus layer, immune system, and hormonal cycle, are key. Recent strides in organoid and microfluidic technologies are propelling research in this domain, offering insights into FRT-microbiota interactions and potential therapeutic avenues. This review delves into the current state of FRT organoid models and microbe integration techniques, evaluating their merits and challenges for specific research objectives. Emphasis is placed on innovative approaches and applications, including integrating organoids with microfluidics, and using patient-derived biobanks, as this offers potential for deeper mechanistic insights and personalized therapeutic strategies. Modeling various FRT properties in organoids is explored, from encompassing age-related epithelial features, oxygen levels, and hormonal effects to mucus layers, immune responses, and microbial interactions, highlighting their potential to transform reproductive health research and predict possible outcomes.

Fig.

1 Integration techniques of microbes into female reproductive tract organoids. ( a ) Suspension culture : organoids are cultured in medium that allows free-floating conditions and enhances cell-to-cell interactions and nutrient absorption. Microbes are introduced into this medium, enabling interaction with the basal side of the organoid structure. ( b ) Microinjection : This technique employs a needle to inject a defined quantity of microbial suspension directly into the organoid's lumen, ensuring localized exposure of the apical side to the microbial agents and facilitating controlled studies of intraluminal microbial effects. ( c ) Fragmentation : Intact organoids are mechanically or enzymatically cleaved into smaller fragments, which are then replated and in the presence of microbial cultures both surrounding the organoid and within the organoid lumen. ( d ) Apical out organoids : The polarity of organoids is reversed to expose the apical surface, which typically lines the organoid lumen, to the external environment. This allows for the direct application of microbes onto the apical interface of the organoids. ( e ) 3D to 2D transition on transwell : Organoids are dissociated to either fragments or into single cells and seeded onto a porous membrane on a transwell. The cells grow into a confluent monolayer, serving as a model of the epithelial barrier. Microbes are added to the upper chamber to study their effects across the epithelial cell layer. ( f ) Organoid-on-a-chip : This method incorporates organoids into a microfluidic system designed to emulate the physical and biochemical aspects of their native tissue environment. Organoids are cultured within defined compartments, and microbes are introduced through microchannels, allowing for real-time observation of dynamic host–microbe interactions under controlled shear stress and fluidic conditions.