Organ culture and how it is kept alive

Ordinary cell culture grows cells in a flat layer, losing the structure of real tissue. To study tissues as they really are, scientists use 3D cultures, organs-on-a-chip, organoids, and organ culture: growing part of an organ, or a whole small organ, so that its tissues keep their natural arrangement and functions.

The tissue must be handled gently and reach the laboratory within minutes. The results are studied by staining with antibodies (immunochemistry), autoradiography and histology (microscope sections).

Keeping the structure intact preserves the communication between cells. But an organ in culture has no blood supply, so oxygen and food must reach the cells by diffusion from the outside. That limits its size: if the piece is too big, its centre may starve and die (necrosis).

So organ cultures are kept at the gas-liquid interface, partly in the medium and partly in the air:

• The liquid level must be just right. Too shallow, and the tissue flattens; too deep, and gas exchange fails.
• A high (sometimes hyperbaric) oxygen level helps, but too much oxygen is toxic.

Organ cultures barely grow, and only in their outer layers, but they stay specialised, helped by growth factors.

Whole embryo culture was pioneered by Spratt in the 1950s: a chick blastoderm (the early embryo on the yolk), cleaned in a balanced salt solution, is placed on a moist cotton-wool pad in a watchglass, and incubated at 37.5 °C.