Search

The FAO recommends the digestible indispensable amino acid score (DIAAS) as the measure for protein quality, for which the true ileal digestibility needs to be assessed in humans or pigs. However, due to high costs and ethical concerns, the FAO strongly encourages as well the development of validated in vitro methods, which complement the in vivo experiments. Method: Recently, an in vitro workflow, based on the validated static INFOGEST protocol, was developed and compared towards in vivo data. In parallel to the validation with in vivo data, the repeatability and reproducibility of the in vitro protocol were tested in an international ring trial (RT) with the aim to establish an international ISO standard method within the International Dairy Federation (IDF). Five different dairy products (skim milk powder, whole milk powder, whey protein isolate, yoghurt, and cheese) were analyzed in 32 different laboratories from 18 different countries, across 4 continents. Results: in vitro protein digestibilities based on Nitrogen, free R-NH2, and total amino acids as well as DIAAS values were calculated and compared to in vivo data, where available. Conclusion: The in vitro method is suited for quantification of digestibility and will be further implemented to other food matrices.

Current organ-on-chip devices suffer from lack of throughput. A multiplexed two-layer device with transparent, through-hole polydimethylsiloxane (PDMS) membrane was developed. This device allows individually addressable cell cultures in a single chip without cross-talk between them. By co-culturing human cerebral microvascular endothelial hCMEC/D3 cells and human astrocytes, the Blood-Brain Barrier was emulated. The visual inspection of cells inside the device was significantly improved with fabricated 2 µm thick membrane.

A realistic model of the blood-brain barrier (BBB) is valuable to perform drug screening experiments and to improve the understanding of the barrier's physiology at normal and pathological conditions. Although the conventional in vitro systems (e.g. Transwell systems) have been used for this, they lack reproducibility and have a static environment. To overcome these disadvantages so called “organs-on-chips‿ have been developed, which use microfluidics and (human) cells to mimic organ function. An example of the BBB chip is shown in the work of Griep et al., where human cerebral endothelial cells (hCMEC/D3) were cultured in a microfluidic device made of polydimethyl siloxane (PDMS). Recently we improved this model. Two PDMS parts with microchannels are placed on top of each other, with a porous membrane in between at the intersection serving as scaffold for the cells. hCMEC/D3 cells (kindly provided by INSERM, Paris, France) were cultured in the chip for up to 15 days. With the four integrated electrodes, which did not block view on the intersection, reliable transendothelial electrical resistance measurements were carried out. Additionally, using immunohistochemistry it was shown that the endothelium expressed tight junction proteins, which is an essential characteristic of the BBB. To further improve the physiological relevance of this promising platform, the cells inside the channels will be cultured under fluid flow. As application, this platform will be used to study the transport of nanocarriers with Alzheimer medication through the BBB. In addition, the clearance of Alzheimer-associated proteins (amyloid β) by the BBB can be examined.

A realistic model of the blood-brain barrier (BBB) is valuable to perform drug screening experiments and to improve the understanding of the barrier's physiology at normal and pathological conditions. Although the conventional in vitro systems (e.g. Transwell systems) have been used for this, they lack reproducibility and have a static environment. To overcome these disadvantages so called “organs-on-chips” have been developed, which use microfluidics and (human) cells to mimic organ function. An example of the BBB chip is shown in the work of Griep et al., where human cerebral endothelial cells (hCMEC/D3) were cultured in a microfluidic device made of polydimethyl siloxane (PDMS). Recently we improved this model. Two PDMS parts with microchannels are placed on top of each other, with a porous membrane in between at the intersection serving as scaffold for the cells. hCMEC/D3 cells (kindly provided by INSERM, Paris, France) were cultured in the chip for up to 15 days. With the four integrated electrodes, which did not block view on the intersection, reliable transendothelial electrical resistance measurements were carried out. Additionally, using immunohistochemistry it was shown that the endothelium expressed tight junction proteins, which is an essential characteristic of the BBB. To further improve the physiological relevance of this promising platform, the cells inside the channels will be cultured under fluid flow. As application, this platform will be used to study the transport of nanocarriers with Alzheimer medication through the BBB. In addition, the clearance of Alzheimer-associated proteins (amyloid β) by the BBB can be examined.