Organoid
A tiny three-dimensional version of a tissue or tumour grown in the lab from a patient's own cells. Tumour organoids keep more of the original cancer's character than flat cell lines and can be used to test drugs on a patient's own cancer.
Grown in a gel that mimics the tissue scaffold, organoids self-organise into structures with the architecture, cell types and mutations of the tissue they came from; tumour organoids can be established from biopsies of colorectal, pancreatic, breast, lung and other cancers within weeks. They are used to model how cancers arise from normal tissue, to screen drugs against many patients' tumours at once, and, in trials, to predict which chemotherapy a given patient will respond to, with early results showing good but imperfect concordance. Their limits are the absence of blood vessels and immune cells (being addressed with co-cultures), variable success rates in establishing them, and the time and cost of doing so for every patient.