CRISPR crops and regenerative medicine

CRISPR crops. CRISPR-Cas9 gene editing is being used to improve nutrition, yield and stress resistance in crops such as rice, tomato and soybean. It is faster and simpler than older methods, and can change several genes at once. Concerns remain: off-target effects (changes in the wrong place), low efficiency in some plants, and how such crops should be regulated.

Regenerative medicine aims to replace damaged cells, tissues and organs, to restore lost function.

Transplants are the oldest form:

• Autograft: tissue moved within one person, such as a skin graft.
• Allograft: from one person to another: kidney, liver, heart.
• Xenograft: from another species, such as pig heart valves.

Organs such as the liver and kidney can regenerate only a little. Stem cells may fill the gap. Grown in a gel called Matrigel with the right growth factors, pluripotent or adult stem cells organise themselves into organoids: tiny, three-dimensional tissues with the structure and function of an organ.

Organoids sit between a flat layer of cells and a whole tissue. They are used to study development, as disease models, to screen drugs and test their toxicity, and to see how well drugs penetrate tumours. Simpler balls of cells, spheroids, can be made in suspension, on non-stick surfaces, in hanging drops, or in microfluidic devices. But 3D culture is costly, slow, hard to automate, and needs experts.

Bioprinting builds scaffolds loaded with cells and growth factors, printed to exactly the right size and shape from a patient's CT or MRI scans.

Some cell therapies are already approved: Carticel (the patient's own cartilage cells, to repair knee cartilage), laViv (the patient's own skin fibroblasts, for wrinkles), and Dermagraft (a patch of donor fibroblasts, for diabetic foot ulcers). Grown blood vessels, windpipes and heart patches are in trials.