Bay Area startup R3 Bio is aiming to revolutionize drug testing by creating ‘organ sacks’—essentially lab-grown organs without brains. Their goal is to use these non-sentient structures to replace animal experiments, particularly monkeys, which are often used for preclinical trials but can be expensive and ethically contentious.

For R3’s backers, like Singapore-based Immortal Dragons, this approach promises a more ethical and scalable alternative. But critics might argue that even if the sacks lack brains, they still pose moral questions about using living tissue for testing. The company is also eyeing larger ambitions: creating human organ sacks to provide donor organs.

While R3 hasn’t publicly demonstrated their monkey organ sacks yet, cofounder Alice Gilman says it’s possible to create these structures through stem-cell technology and gene editing. They envision the sacks being used for drug toxicity testing, a practice that currently involves significant animal suffering.

The US Animal Welfare Act mandates minimizing pain for research animals, but this isn’t always feasible, as evidenced by the 2024 fiscal year data showing over 60,000 nonhuman primates were used in tests. About 1,200 of these experiences maximal or unmitigated pain.

As R3 moves towards creating human organ sacks, they face not just ethical debates but also the challenge of ensuring that any engineered organs are safe and suitable for transplant. The race is on to find solutions that could alleviate the global organ shortage while sidestepping the moral complexities of using living tissue in research.