Cervix-on-a-chip for investigating ascending Ureaplasma parvum infection in pregnancy

Abstract

To develop a microfluidic cervix-on-a-chip (COC) to study ascending bacterial infection in pregnancy. COC with 6 interconnected culture chambers connected by microchannels containing cells from vagina (VEC), cervical epithelium and stroma, transition zone, and decidua was developed. Cells in COC were characterized by morphology and expression of cell-specific markers. An ascending Ureaplasma parvum (UP) infection was tested by inoculating UP (107 CCU) in VEC. Propagation of infection in COC (fluorescent microscopy), cytotoxicity (LDH assay) and inflammation (cytokine assays) by UP (107 or 1010 CCU) were determined. For physiological validation of in vitro data, we inoculated UP vaginally (107 or 1010 CCU) in pregnant mice and monitored for preterm birth (PTB). Cellular characteristics (morphology, collagen production, and expression of markers) in the COC were as seen in vivo, validated devices’ physiological relevance (Fig. 1). In vitro, ascending U. parvum colonized the cervical epithelial and decidual cells within 48 h. Both low and high dose UP colonization did not promote cell death in any of the COC cells. Low dose UP increased IL-8 (stroma) while high dose UP increased GM-CSF (ectocervix) and IL-8 (stroma), and IL-6 and IL-8 (decidua) (Fig. 1). Vaginal inoculation of low and high doses of UP infection had no or 20% PTB rate, respectively compared to 90% PTB rate in E. coli models (positive control). Intraamniotic injection of low dose UP increased PTB rate to 67% (Fig. 2). In vitro cervix-on-a-chip model of ascending infection showed UP colonization with poor immunogenicity. This finding was recapitulated in vivo. Validated COC is useful for in vitro preclinical studies in pregnancy and parturition.View Large Image Figure ViewerDownload Hi-res image Download (PPT)