Lab+Life Scientist Jan 2014

Page 44


Cross-section of multicellular bioprinted human liver tissue, stained with hematoxylin & eosin (H&E).

the loss of function has limited their usefulness. What is needed is a method whereby hepatocytes can be maintained in culture environments that support polarisation and three-dimensionality and so retain critical functions for longer periods outside the body.

Cross-section of bioprinted human liver tissue demonstrating compartmentalisation between the hepatocytes (shown as blue nuclei), endothelial cells (red) and hepatic stellate cells (green).

The image above shows formation of intercellular junctions between hepatocytes in bioprinted liver tissue, highlighted by E-Cadherin immunochemistry (green).

“... bioprinting ... enables fabrication and comparative testing ... so that winning combinations can be identified systematically based on histological and functional outcomes.”

Bioprinted liver tissue model Organovo’s NovoGen Bioprinting platform has

activities, including CYP1A2 and CYP3A4.

using Organovo’s proprietary 3D bioprinting

been used to generate bioprinted liver tissue

Production of the liver-specific protein, albumin,

technology that builds functional living tissues

prototypes that contain both parenchymal and

was 5 to 9 times greater on a per-cell basis when

containing precise and reproducible architecture.

non-parenchymal cells in spatially controlled, user-

compared to matched 2D controls. These functional

The tissues are functional and stable for at least

defined geometries that reproduce compositional

data, combined with the unique histological features

42 days, which enables assessment of drug effects

and architectural features of native tissue.

of the tissues, suggest they may be a compelling

over study durations well beyond those offered by

One advantage of the automated bioprinting

alternative to traditional 2D hepatocyte cultures

industry-standard 2D liver cell culture systems.

platform is that it enables fabrication and

for predictive studies, especially those involving

Organovo has previously shown that exVive3D

comparative testing of multiple compositions and

longer-term tissue toxicity assessments or studies

Liver Models produce important liver proteins

geometries so that winning combinations can be

of disease development and progression where

including albumin, fibrinogen and transferrin,

identified systematically based on histological and

results need to be interpreted in the context of

synthesise cholesterol and possess inducible

functional outcomes.

cell-cell interactions.

cytochrome P450 enzymatic activities, including

Beginning with hepatocytes (the predominant

The overall goal of studies like these is to

CYP 1A2 and CYP 3A4. The exVive 3D Liver has

parenchymal cells of the liver), designs were created

develop living, multicellular human tissues that can

successfully differentiated between structurally

based on shapes and cellular interfaces found

be maintained in the laboratory environment for

related compounds with known toxic and non-

in native liver tissue. Non-parenchymal cells,

extended periods of time and sampled serially for

toxic profiles in human beings and the model has

including endothelial cells and hepatic stellate

both functional and histological changes in response

also been employed successfully in the detection

cells, were positioned in defined locations relative

to injury, pathogens or treatments.

of metabolites at extended time points in vitro.

to hepatocytes, creating a compartmentalised

Importantly, the configuration of the bioprinted liver tissues enables both biochemical and histologic

fabrication and substantially maintained over

3D bioprinted human liver tissue now available

time in culture.

Using 3D bioprinting technology, Organovo

compound responses at multiple levels.

architecture that was established at the time of

data to be collected so that a customer can investigate

In addition to the cell type-specific

Holdings has released its exVive3D Human Liver

The durability and functionality of the 3D

compartmentalisation, two histomorphological

Tissue for preclinical drug discovery testing. This

liver product enable the assessment of the effects

features can be appreciated in these bioprinted

model is intended to provide human-specific data

of low dose or repeated dosing regimens across a

liver tissues: 1. The development of microvascular

to aid in the prediction of liver tissue toxicity or

spectrum of biochemical, molecular and histologic

networks within the tissue; and 2. the formation of

ADME outcomes in later-stage preclinical drug

end points. Initially, users will be able to access the

tight intercellular junctions among the hepatocytes.

discovery programs.

technology through Organovo’s contract research

Importantly, these multicellular, 3D liver tissues

Organovo’s exVive3D Liver Models are

services program. All testing will be performed at

possess critical attributes central to liver function,

bioprinted, living 3D human liver tissues consisting

Organovo’s facility by the company’s laboratory

including production of liver-specific proteins

of primary human hepatocytes, stellate and

services tissue experts.

such as albumin and transferrin, biosynthesis

endothelial cell types, which are found in native

of cholesterol and inducible cytochrome P450

human liver. The exVive3D Liver Models are created

Organovo Holdings

44 | LAB+LIFE SCIENTIST - January 2015