The dawn of organoids
2000s
THE PARALLEL EVOLUTION OF
Advances in stem cell biology hinted that cultured cells might be capable of
milestone
more than forming flat, monolayer sheets. In the early 2000s, a few laboratories
ORGANOIDS AND HIGH-CONTENT IMAGING
began to explore whether stem cells, when given the right cues, could grow
into tissues the same way they do inside the embryo.
In 2008, Yoshiki Sasai, a stem cell biologist at RIKEN Center for Develop
mental
Biology, developed a culture system that mimicked the early embryo
environment. Within days, mouse embryonic stem cells cultured in it sponta
Over the past three decades, two powerful trends have converged: 3D
neously
arranged themselves into polarized, multilayered cortical tissue that
organoids and imaging technologies built to study them. As scientists
later produced neurons resembling those in the developing mouse cortex. By
learned to grow tiny tissues to model disease and test therapies,
TOP IMAGE:
1996
adding a few signaling molecules, the team could even steer the emerging
Hans Clevers
engineers continually advanced imaging tools that enabled more ambitious
tissue toward different regions of the cortex, or into neighboring structures (4).
pioneered
organoid research by
Half a world away, molecular geneticist Hans Clevers at the Hubrecht Insti
experiments. Their intertwined efforts have reshaped how researchers
generating
tute
made a similar discovery in a different organ. In a dish supplied with a
self-renewing intestinal
observe, measure, and understand complex human biology.
organoids from single stem
handful of growth factors, intestinal stem cells marked by the gene Lgr5 — a
cells. RIGHT: Organoids are
key identifier of stem cells in the gut — generated miniature gut-like structures
A faster
defined as miniature 3D
tissues that self-organize and
complete with crypts, villus-like domains, and all major epithelial cell types.
differentiate into functional
way to see
These structures could maintain themselves for months without their native
cell types, recapitulating key
features of organs in vitro.
supporting mesenchymal niche.
living cells
Clevers published this work in 2009 and used “organoids” to describe the
Imaging going
self-organizing tissues (5). Since then, organoid — a word that once described
IMAGE LEFT:
The CSU10
small tissue fragments taken directly from organs — has taken on a widely
In the 1990s, confocal microscopy had become indispensable for imag
high content
introduced a dual
recognized new meaning: mini clusters of cells grown in vitro that self-organize
spinning-disk
ing
thick, three-dimensional biological samples, such as tissues and small
and differentiate into functional cell types,
design, enabling
organisms. Its major limitation, however, was speed. Because point-scanning
real-time, gentle
recapitulating the structure and function
As organoid research quietly gathered momentum, Yokoga
imaging that
confocal microscopes illuminated a single spot at a time, live-cell imaging was
of an organ in vivo (6).
wa’s
engineers were wrestling with a new strategic question.
overcame the
slow and phototoxic, often resulting in blurred, ghost-like images.
speed limits of
Drug screening was moving toward automation, and they realized the spinning-disk
traditional
Around this time, Yokogawa — then best known for industrial measure
2008
unit on its own could not meet this need. They set out to build a complete imaging system
confocal systems.
ment
systems — began exploring life science imaging. To understand what
IMAGE BELOW:
that could run complex experiments by itself.
Breakthroughs
biologists needed, engineer Takeo Tanaami and his colleagues at Yokogawa
Yasunori Yokoyama, an optics engineer, joined the company in 2005 just as this project
in stem cell
biology laid the
trained at a university medical school. During one imaging session, a professor
was starting. His first task was to help build the optical system for a high-content analysis
groundwork
(HCA) platform. At the time, most microscopy systems changed focus by moving the
watched the confocal microscope struggle to keep up with beating cardiac cells
for the organoids
and other 3D cell
entire turret of objective lenses. Such an assembly was simply too heavy and too slow
and noted, “We need a confocal system about a thousand times faster” (1).
models.
for an automated platform expected to scan hundreds of wells.
To reach that speed, Tanaami found promise in the spinning disk — a rotating
“We developed the mechanics to move only one objective despite that there are
metal disk with a spiral array of pinholes, originally invented for video trans
multiple objectives on the turret,” Yokoyama explained. The redesigned system would
mission.
However, this disk had not been widely used for biological imaging
select a single lens and move only that piece to adjust focus.
since most of the illumination light could not pass through the pinholes, making
With much less mass to move, the system could focus more quickly and remain stable
images extremely dim, like “trying to see stars during the day” (1).
during long automated runs. The first prototype, Yokoyama recalled, had “thousands
The breakthrough came when Tanaami realized that placing a microlens
of wire cables and hundreds of terminal blocks” — a light-yellow bundle the team
in front of each pinhole could collect far more light. By precisely aligning a
nicknamed “spaghetti.”
microlens array disk with the pinhole disk, the Yokogawa engineers devel
After years of iteration, the pieces came together. In 2008, Yokogawa introduced the
oped
the game-changing dual microlensed spinning disk technology, achiev
CellVoyager CV6000, its first fully integrated HCA system. Three years later, the CV7000
ing
both speed and brightness, which serves as the backbone of Yokoga
followed, boosting processing speed roughly fourfold and enabling imaging of a 384-
wa’s
imaging platforms.
well plate in just four minutes. Although originally designed for drug screening, these
systems, which integrated fast 3D spinning-disk confocal imaging with high-content
In 1996, Yokogawa released the CSU10, its first spinning-disk confocal scan
formats, laid the technical foundation needed for organoids that were becoming instru
ner
unit capable of imaging living cells and 3D biological samples in real time
mental
in drug discovery.
— roughly a thousand times faster than conventional confocal microscopes.
Meanwhile, stem cell biology was advancing quickly. From isolating
TOP RIGHT: Yasunori Yokoyama (center) played a key role in developing
Yokogawa’s HCA platforms and is pictured here with colleagues. Back row (left to
mouse pluripotent stem cells to developing human embryonic stem cell lines,
right): Koji Oohashi, Yasunori Yokoyama, Yousuke Kawabata, Takumi Fukuda. Front
researchers were laying the foundation for organoids and 3D cell models that
row: Nao Koishihara, Katsuya Tajiri. BOTTOM RIGHT: The CellVoyager CV6000 was
Yokogawa’s first fully integrated HCA system for automated 3D imaging.
would soon follow (2,3).
CREDIT: YOKOGAWA
CREDIT: ISTOCK.COM/KYNNY
CREDIT: WIKIMEDIA COMMONS
CREDIT: INTERO BIOSYSTEMS
CREDIT: YASUNORI YOKOYAMA, YOKOGAWA
CREDIT: YOKOGAWA
