Augmenting Epithelial Barrier Function

The simplest multicellular animal organisms, coelenterates, are essentially floating intestines in the sea. More fundamentally, they are ‘barrier tubes’ that attempt to compartmentalize the environment they exist in. It is said that ontogeny recapitulates phylogeny. It is thus interesting that the blastocyst, among the earliest multicellular embryonic structures, is essentially a sac comprised of polarizing cells. Like the coelenterate, it is also compartmentalizing the environment that it exists in, creating an internal fluid compartment distinct from an external one. So on both an evolutionary basis and a developmental basis, the singular importance of fluid compartmentation and barrier cell linings was a concept that nature apparently grabbed hold of with both hands and never let go, as it kept ramifying the theme. The human body is in a sense a manifold of many different sacs and tubes: a respiratory tract, a GI tract, a urinary tract, the skin, a reproductive tract, a vasculature, a central nervous system encased in a medium (cerebrospinal fluid) quite distinct from blood. We are intimately and fundamentally divided into luminal and abluminal compartments.