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Integrated Tissue Slice Culture and NMR Metabolomics – A Novel Approach Towards Systemic Understanding of Liver Function And Disease

Periodic Reporting for period 2 - TISuMR (Integrated Tissue Slice Culture and NMR Metabolomics – A Novel Approach Towards SystemicUnderstanding of Liver Function And Disease)

Periodo di rendicontazione: 2019-01-01 al 2021-12-31

he TISuMR project seeks a radically new approach to
tissue culture by integrating microfluidic lab-on-a-chip technology with
advanced nuclear magnetic resonance spectroscopy and imaging.
Liver tissue slices are thin slivers of living liver tissue.
Kept alive by perfusion with
a solution containing the necessary nutrients plus oxygen, they can be
used as a highly realistic model of the liver for the testing of drugs and
for studying how liver disease develops and how it can be cured.
Nuclear magnetic resonance spectroscopy can provide detailed information
on the metabolism of living tissue without interfering with it in any way.
The TISuMR project aims to combine these two approaches to provide a radically
new experimental approach for the life sciences.

Liver tissue slices are small, weighing only of the order of 1 mg. Obtaining
good quality NMR data from such small samples is a challenge, and requires
careful optimisation of the NMR detectors to the exact geometry of the slice.
The major challenge in TISuMR therefore lies in developing NMR detectors that
are among the world's best in terms of sensitivity, but can still be integrated
easily with the microfluidic systems required to keep the tissue slices healthy
over a period of time.

The first part of the project was dedicated to the development and validation of the
necessary technology. In the second part, the technology is to be applied
to the study of a particular form of liver disease, cholestasis.
he project has led to the development of
a novel NMR detection system based on a transmission line
probe, interfaced with a lab-on-a-chip perfusion device. The combined
system has been demonstrated to maintain tissue viability while allowing
detailed and quantitative observation of the tissue metablism by NMR
spectroscopy. This represents a very significant technological step, with
far-reaching applications in the life sciences. A patent application
for this system has been filed, and initial steps towards commercial exploitation
have been initiated together with an SME partner.

Its development was challenging, since prior implementations of such perfusion
systems did not take into account the specific requirements of a high-resolution
magnetic resonance environment (extremely homogeneous, large magnetic fields).
A second, complementary approach is based on the realisation that lab-on-a-chip
systems can be driven by spinning. The resulting centrifugal forces can
be used to move liquids in the device in a controlled way. At the same time,
spinning is frequently used in solid-state NMR spectroscopy as a means to
improve the sharpness of spectral lines, increasing the ability to distinguish
closely related chemical compounds from each other.
A lab-on-a-disk system that combines these two approaches has been developed, in order to
allow perfusion culture of liver tissue slices, while simultaneously
improving the resolution of their NMR spectra.
In the reporting period,
a protocol has been developed for quantitative observation of metabolic consumption/production
rates of live
mouse liver tissue. The method has been used to compare the impact of
drug-induced cholestasis, a common and troublesome side effect of many drugs,
on tissue metabolism. The results have been correlated with a comprehensive
study of bile transporter expression under the same conditions.
The NMR probe technology that allows integration of microfluidic perfusion
systems with high-resolution nuclear magnetic resonance (NMR) spectroscopy
represents a significant step beyond the existing state of the art.
To date, only very simple microfluidic NMR systems have been demonstrated.
While these have been limited to a capillary through which the microfluidic sample must be
pumped, the new designs developed and proved as part of TISuMR can
accommodate arbitrarily complex mircofluidic systems. This has deep implications
in that it provides the emerging field of microfluidic lab-on-a-chip systems
with a new modality of observation, which is largely orthogonal to the existing
ones: NMR is non-invasive, gives system-wide information on the metabolic
activitives of live systems, and is an inherently quantitative technique.

The characterisation of cholestasis on the level of liver tissue is also an
important step forward. Many important drugs are limited in their use by
cholestatic side effects, and drug-induced cholestasis leads to the eliminiation
of a large number of otherwise promising new drug candidates.

On the whole, the TISuMR project has turned what was at best a "future" technology
into a very much emerging one.
The result is a new technological platform for the culture and detailed metabolic observation of
live tissue samples, with important implications across the life sciences.
Magnetic resonance images of liver tissue slices
Group photo from the Project symposium, held near Southampton, September 2017
Prototype of Lab-on-a-disk NMR system
Microfluidic NMR/Perfusion device and live tissue metabolic data