PhD student, University Of South Australia/Future Industries Institute
Bioengineering, Health Sciences, Drug Delivery
My research is focused on developing and optimizing an intestine-on-a-chip model. It is the next-generation of the static in vitro model that we use in the laboratory. It mimics the peristalsis of the small intestine in a microfluidic chip where intestinal absorptive like-cells (Caco-2) grow and form an epithelial monolayer after only 5 days (compared to 21 days in standard dish). These cells in the chip also behave much more like in the human intestine, can secrete mucus, express drug transport proteins, microvilli and form a stronger barrier than in a simple well. In parallel, I showed that these cellular changes are specifically due to the shear stress applied on the top of the cells with the fluid flow created in the chip. This more realistic and dynamic model enables me to test different particulate carrier for oral vaccines to improve their formulation. My research is part of a collaboration with a pharmaceutical company based in Sydney which make such carriers and try to understand how well they can be absorbed by intestinal cells. This research is very important for the development of new oral vaccines and improving their efficiency in the human body. This model has also a number of advantages compared to the static models that most researchers use today: it is easy and cheap to make, uses smaller amount of cell culture medium and cells, takes less time to grow the cells and is closer to the complexity of the human intestine. It will hopefully help answering drug delivery questions more accurately.
Abstract: Here we describe a method for fabricating a primary human Small Intestine-on-a-Chip (Intestine Chip) containing epithelial cells isolated from healthy regions of intestinal biopsies. The primary epithelial cells are expanded as 3D organoids, dissociated, and cultured on a porous membrane within a microfluidic device with human intestinal microvascular endothelium cultured in a parallel microchannel under flow and cyclic deformation. In the Intestine Chip, the epithelium forms villi-like projections lined by polarized epithelial cells that undergo multi-lineage differentiation similar to that of intestinal organoids, however, these cells expose their apical surfaces to an open lumen and interface with endothelium. Transcriptomic analysis also indicates that the Intestine Chip more closely mimics whole human duodenum in vivo when compared to the duodenal organoids used to create the chips. Because fluids flowing through the lumen of the Intestine Chip can be collected continuously, sequential analysis of fluid samples can be used to quantify nutrient digestion, mucus secretion and establishment of intestinal barrier function over a period of multiple days in vitro. The Intestine Chip therefore may be useful as a research tool for applications where normal intestinal function is crucial, including studies of metabolism, nutrition, infection, and drug pharmacokinetics, as well as personalized medicine.
Pub.: 15 Feb '18, Pinned: 06 Mar '18
Abstract: Existing in vitro models of human intestinal function commonly rely on use of established epithelial cell lines, such as Caco-2 cells, which form polarized epithelial monolayers but fail to mimic more complex intestinal functions that are required for drug development and disease research. We show here that a microfluidic 'Gut-on-a-Chip' technology that exposes cultured cells to physiological peristalsis-like motions and liquid flow can be used to induce human Caco-2 cells to spontaneously undergo robust morphogenesis of three-dimensional (3D) intestinal villi. The cells of that line these villus structures are linked by tight junctions, and covered by brush borders and mucus. They also reconstitute basal proliferative crypts that populate the villi along the crypt-villus axis, and form four different types of differentiated epithelial cells (absorptive, mucus-secretory, enteroendocrine, and Paneth) that take characteristic positions similar to those observed in living human small intestine. Formation of these intestinal villi also results in exposure of increased intestinal surface area that mimics the absorptive efficiency of human intestine, as well enhanced cytochrome P450 3A4 isoform-based drug metabolizing activity compared to conventional Caco-2 cell monolayers cultured in a static Transwell system. The ability of the human Gut-on-a-Chip to recapitulate the 3D structures, differentiated cell types, and multiple physiological functions of normal human intestinal villi may provide a powerful alternative in vitro model for studies on intestinal physiology and digestive diseases, as well as drug development.
Pub.: 03 Jul '13, Pinned: 06 Mar '18
Abstract: Many highly effective chemotherapeutic agents can only be administered intravenously as their oral delivery is compromised by low gastro-intestinal solubility and permeability. SN-38 (7-ethyl-10-hydroxycamptothecin) is one such drug; however, recently synthesized lipophilic prodrugs offer a potential solution to the low oral bioavailability issue. Here we introduce a microfluidic-based intestine-on-a-chip (IOAC) model, which has the potential to provide new insight into the structure–permeability relationship for lipophilic prodrugs. More specifically, the IOAC model utilizes external mechanical cues that induce specific differentiation of an epithelial cell monolayer to provide a barrier function that exhibits an undulating morphology with microvilli expression on the cell surface; this is more biologically relevant than conventional Caco-2 Transwell models. IOAC permeability data for SN38 modified with fatty acid esters of different chain lengths and at different molecular positions correlate excellently with water–lipid partitioning data and have the potential to significantly advance their preclinical development. In addition to advancing mechanistic insight into the permeability of many challenging drug candidates, we envisage the IOAC model to also be applicable to nanoparticle and biological entities.
Pub.: 15 May '17, Pinned: 06 Mar '18