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Self-organization of stem cells into embryos: A window on early mammalian development p. 948

Cancer modeling meets human organoid technology p. 952

Organoids by design p. 956

Organoids-on-a-chip p. 960

946 7 JUNE 2019 • VOL 364 ISSUE 6444

Less complex than a whole organ but more representative than clusters

of cells in culture, organoids are composed of specifi c cell types that

self-organize and recapitulate various aspects of organogenesis.

As such, these 3D models enable studies of early organ devel-

opment and tissue interactions. Furthermore, when constructed

from patient-derived cells, they help us understand what happens

in the disease state, including cancer. However, organs in a dish

only approximate the real thing. They lack elements of the natu-

ral environment that are critical for infl uencing cell dynamics

and morphogenesis. In addition, multiple cell lineages may contribute

to a single organ, or physical features may be key. Hence, research-

ers are tasked with identifying and reconstructing these elements and

interactions—whether they involve coculture with other cells to gener-

ate vasculature and provide innervation, or simulation of fl uid fl ow

as with organoids-on-a-chip. These engineered biological constructs

can then more closely approximate nature’s form and function.

Continued tweaking of methods will yield exciting advances and

solve classical embryology questions surrounding the generation of

the three germ layers, breaking of symmetry, and axis formation,

and may eventually lead to the replacement of faulty body parts

though transplantation of organoid-generated tissues and organs.

By Beverly A. Purnell and Marc Lavine

ORGANS

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7 JUNE 2019 • VOL 364 ISSUE 6444 947SCIENCE sciencemag.org

Lung-on-a-chip. The red and blue chambers are where airway cells are cultured to model human small airways. The device has six chambers for the generation

of six biological replicates. PHOTO: THE BIOLINES LABORATORY DIRECTED BY D. HUH AT THE UNIVERSITY OF PENNSYLVANIA

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Approximating organsBeverly A. Purnell and Marc Lavine

DOI: 10.1126/science.aay1351 (6444), 946-947.364Science 

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