bacterial inoculation of organ chips with differentiated human vaginal epithelial cells for studying living vaginal microbiome under microaerophilic conditions

Microfluidic Vagina Chip for Studying the Vaginal Microbiome

A vaginal microbiome dominated by Lactobacillus spp. that helps to maintain an acidic microenvironment plays an important role in maintaining female reproductive health1. However, at times there can be a change in the composition of microbial communities that comprise the microbiome, which results in an increase in the diversity of vaginal bacteria. These dysbiotic changes, which often result in a switch from a Lactobacillus-dominated state to one dominated by more&#160;diverse anaerobic bacterial species (e.g., Gardnerella vaginalis), are associated with various diseases of the reproductive system, such as bacterial vaginosis, atrophic vaginitis, urinary tract infection, vulvovaginal candidiasis, urethritis, and chorioamnionitis2,3,4,5. These diseases, in turn, increase a woman&#39;s chances of acquiring sexually transmitted diseases and pelvic inflammatory disease6,7,8,9. They also pose a higher risk for pre-term birth and miscarriages in pregnant women10,11,12 and have also been implicated in infertility13,14,15,16.
Although efforts have been made to model vaginal dysbiosis using vaginal epithelial cells cultured in static, two-dimensional (2D) culture systems17,18, they do not effectively mimic the physiology and complexity of the vaginal microenvironment19. Animal models also have been used to study vaginal dysbiosis; however, their menstrual phases and host-microbiome interactions differ greatly from that in humans, and thus, the physiological relevance of results from these studies remains unclear19,20,21. To counteract these issues, organoids and Transwell insert models of human vaginal tissue also have been used to study host-pathogen interactions in the FRT19,22,23,24. But because these are static cultures, they can only support co-culture of human cells with living microbes for a short period of time (&#60;16-24 h), and they lack many other potentially important physical features of the human vaginal microenvironment, such as mucus production and fluid flow22.
Organ Chips are three-dimensional (3D) microfluidic culture systems that contain one or more parallel hollow microchannels lined by living cells cultured under dynamic fluid flow. The two-channel chips enable the recreation of organ-level tissue-tissue interfaces by culturing different cell types (e.g., epithelium and stromal fibroblasts or epithelium and vascular endothelium) on opposite sides of a porous membrane that separates the two parallel channels (Figure 1). Both tissues can be independently exposed to fluid flow, and they can also experience microaerobic conditions to enable co-culture with a complex microbiome25,26,27,28. This approach was recently leveraged to develop a human Vagina Chip lined by hormone-sensitive, primary vaginal epithelium interfaced with underlying stromal fibroblasts, which sustains a low physiological oxygen concentration in the epithelial lumen and enables co-culture with healthy and dysbiotic microbiomes for at least 3 days in vitro29. It was demonstrated that the Vagina Chip could be used to study colonization by optimal (healthy) L. crispatus consortia and detect inflammation and injury caused by non-optimal (non-healthy) G. vaginalis containing consortia.&#160;Here, we describe in detail the methods that are used to create the human Vagina Chip as well as to establish healthy and dysbiotic bacterial communities on-chip.

Author Spotlight: Revolutionizing Research on Vaginal Microbiome Interactions Using a Vaginal Chip

Modeling Healthy and Dysbiotic Vaginal Microenvironments in a Human Vagina-on-a-Chip

We successfully developed a human vagina chip that supports spontaneous differentiation of squamous stratified vaginal epithelium, forms a strong barrier, responds to hormones, and generates a microbiome supporting oxygen gradients. 2D and organoid cultures are currently used to study vaginal dysbiosis, but they aren't able to mimic the physiological complexities of the vaginal microenvironment due to their static nature. Animal models too can't model the same hormonal changes present in the human menstrual cycle, and the vaginal microbiome across animal species and humans differ.We set out to explore whether organ chip technology can be used to develop a preclinical model of human vagina microbiome interactions, which could potentially be used for discovery and assessment of potential microbiome-based therapeutics. The vagina chip allows for dynamic fluid flow across the vaginal epithelium and stroma, which prolongs its co-culturing with vaginal microbial consortia and maintains a physiologically relevant microenvironment. The human vagina-on-a-chip is an exciting tool that can be used to study varying diseases of the female reproductive tract and validate new biotherapeutics.

Bacterial Inoculation of Organ Chips with Differentiated Human Vaginal Epithelial Cells for Studying Living Vaginal Microbiome Under Microaerophilic Conditions

bacterial-inoculation-organ-chips-with-differentiated-human-vaginal

Research

JoVE Journal

Bioengineering

Women's health, and particularly diseases of the female reproductive tract (FRT), have not received the attention they deserve, even though an unhealthy ...