Nanostructure generation during milk digestion in presence of a cell culture model simulating the small intestine

Claudia Hempt,Stefan Salentinig,Tina Buerki-Thurnherr,Mark Gontsarik,Cordula Hirsch

doi:10.1016/j.jcis.2020.04.059

Abstract

HypothesisThe development of advanced oral delivery systems for bioactive compounds requires the fundamental understanding of the digestion process within the gastrointestinal tract. Towards this goal, dynamic invitro digestion models, capable of characterising the molecular as well as colloidal aspects of food, together with their biological interactions with relevant invitro cell culture models, are essential. ExperimentsIn this study, we demonstrate a novel digestion model that combines flow-through time resolved small angle X-ray scattering (SAXS) with an invitro Caco-2/HT-29 cell co-culture model that also contained a mucus layer. This set-up allows the dynamic insitu characterisation of colloidal structures and their transport across a viable intestinal cell layer during simulated digestion. FindingsAn integrated online SAXS – invitro cell co-culture model was developed and applied to study the digestion of nature’s own emulsion, milk. The impact of the invitro cell culture on the digestion-triggered formation and evolution of highly ordered nanostructures in milk is demonstrated. Reported is also the crucial role of the mucus layer on top of the cell layer, protecting the cells from degradation by digestive juice components such as lipase. The novel model can open unique possibilities for the dynamic investigation of colloidal structure formation during lipid digestion and their effect on the uptake of bioactive molecules by the cells.

Highlights

There is a growing interest to understand, control, and manipulate the process of lipid digestion within the gastrointestinal tract (GIT) with functional food materials, in regards to the development of emulsion-based systems for the delivery of hydrophobic and amphiphilic bioactive compounds [1,2,3,4]
The measurements were performed on the cSAXS beamline at the Swiss Light Source, Paul Scherrer Institute (PSI, Villigen, Switzerland) with an X-ray beam having a wavelength of 1.0 Å at X-ray energy of 12.4 keV
To the best of our knowledge, this is the first demonstration of a digestion platform with an integrated co-culture model for online in situ investigation of lipid digestion and transport with synchrotron small angle X-ray scattering (SAXS)

Summary

Introduction

There is a growing interest to understand, control, and manipulate the process of lipid digestion within the gastrointestinal tract (GIT) with functional food materials, in regards to the development of emulsion-based systems for the delivery of hydrophobic and amphiphilic bioactive compounds [1,2,3,4]. A comprehensive understanding of the food-digestion interactions that allows the rational design of functional food materials requires a fundamental knowledge of the effect of individual digestion parameters such as bile salt concentration, pH, lipases, and interactions with mucus layer and cells, on the process. This is only possible with suitable in vitro models that offer the flexibility to modify selected parameters, within and even beyond the physiologically relevant range. Most of the dynamic in vitro models were not successful in recreating the physiological conditions as the interaction and absorption of water, nutrients and metabolites could not be routinely simulated [6]

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Results

Conclusion