Headless “Organ Sacks” Could Replace Animal Testing | Biotech News
A Bay Area biotechnology startup, R3 Bio, is developing “organ sacks”—complex structures containing fully formed organs but lacking a brain—as a potential replacement for animals in research, as the Trump administration continues to phase out animal experimentation across the federal government.
R3 Bio has been pitching the concept to investors and within the scientific community as a way to circumvent the ethical concerns associated with live animal testing. The company’s cofounder, Alice Gilman, stated the long-term objective is to create human versions of these organ sacks, which could serve as a source of tissues and organs for transplantation, according to information shared with potential investors.
The idea has attracted backing from For Immortal Dragons, a Singapore-based longevity fund. CEO Boyang Wang articulated the fund’s investment strategy, stating, “We reckon replacement is probably better than repair when it comes to treating diseases or regulating the aging process in the human body.” Wang added that a “nonsentient, headless bodyoid for a human being” could be a significant source of organs.
Currently, R3 Bio is focused on developing organ sacks using monkey physiology. Gilman explained that the scalability of testing would be significantly improved by utilizing ethical, organ-system-exclusive models. The company’s name references the “three R’s”—replacement, reduction, and refinement—a framework established in 1959 by British scientists William Russell and Rex Burch to promote humane animal experimentation.
Monkeys are frequently used in preclinical drug trials before human clinical trials begin, notably during the Covid-19 pandemic for vaccine and therapeutic development. However, the availability of monkeys for research has decreased, particularly after China banned the export of nonhuman primates in 2020. This scarcity is compounded by growing pressure on the seven federally funded primate research facilities in the US, with at least one considering a transition to a sanctuary. The Centers for Disease Control and Prevention is also reducing its reliance on monkey research as part of a broader governmental shift.
Gilman argues that the current shortage of research monkeys poses a risk, suggesting there may not be enough available if another pandemic emerges. Organ sacks, she believes, could offer a solution.
These organ sacks are intended to surpass the limitations of existing organ-on-chip or tissue models, which lack the full complexity of whole organs, including a functioning vascular system. R3 Bio has reportedly created mouse organ sacks without brains, though Gilman and cofounder John Schloendorn have not confirmed this directly. Gilman clarified her preference for describing the structures as “designed to only have the things we desire,” rather than “brainless.”
The precise method for creating monkey and human organ sacks remains undisclosed, but the founders indicated they are exploring a combination of stem-cell technology and gene editing. Paul Knoepfler, a stem cell biologist at the University of California, Davis, suggested that induced pluripotent stem cells—adult skin cells reprogrammed to an embryonic-like state—could be used. By editing these stem cells to disable genes essential for brain development, scientists could potentially grow embryo-like structures that develop into organized organ systems.