A Technique to Establish a Bacterial Infection Model in an Ex Vivo Organ Culture

Take a human placental organ culture grown on an extracellular matrix, or ECM.

The culture exhibits a villi-like structure with an outer syncytium — a multinucleate trophoblast layer — and underlying cytotrophoblasts, or CBTs, which differentiate into extravillous trophoblasts, or EVTs, that anchor into the ECM.

Introduce Listeria monocytogenes, a pathogenic bacteria.

Internalins — the bacterial surface proteins — bind to EVT receptors, facilitating bacterial internalization via endocytosis.

The internalized bacteria secrete pore-forming toxins and phospholipases that perforate the vacuolar membrane, mediating its rupture and bacterial escape into the cytoplasm.

The escaped bacteria recruit host machinery for actin polymerization, propelling them toward the host cell membrane.

Secretion of a bacterial virulence factor induces protrusion formation on the host membrane. Neighboring cells engulf the bacteria-containing protrusion, causing infection spread.

The bacteria spread via EVTs to the underlying CBTs.

Add an antibiotic to remove the extracellular bacteria, preparing the infection model for analysis.