© DUSAN PETRICICLate last year, Steve Goldman of the University of Rochester and his colleagues reported that they had transplanted immature glial cells from donated human fetuses into the brains of immunodeficient mouse pups. These human glial cells matured into astrocytes and developed as the primary astrocyte population in the newborn mouse brain. One unexpected outcome of the team’s research, published in the Journal of Neuroscience (34:16153-61), was that these human-mouse chimeras outperformed normal mice almost fourfold in a variety of cognition tests, underscoring the importance of astrocytes in regulating synaptic plasticity and neural connectivity to enhance learning and memory. But the study also raised important ethical considerations—namely, what biological properties differentiate Homo sapiens from other organisms, and when should such “humanized” animals be afforded the rights that people currently enjoy.
Goldman is quick to state that the enhanced memory and learning performance of these human-mouse chimeras did not make the mice more human. “It’s still a mouse brain, not a human brain, but all the non-neuronal cells are human,” Goldman told New Scientist at the time of the publication. “This does not provide the animals with additional capabilities that could in any way be ascribed or perceived as specifically human. Rather, the human cells are simply improving the efficiency of the mouse’s own neural networks. It’s still a mouse.”
At the same time, the team had ethical reservations about repeating these types of experiments on monkeys, presumably following the National Academies’ guidelines that no human embryonic stem cells should be introduced into nonhuman primates at ...
