The implanted stem cells, however, were human. (The fact that that the treatments did not cause "fever or substantial changes in immune cell levels (lymphocytes, neutrophils, and monocytes), which are commonly monitored for xenograft-related immune responses," is itself surprising.)

> promises of extending life have always fallen short of hype, and odds are this will too

Correct, though I'd say because this is early-stage medical research. Not because it's targeting longevity. I'd be similarly sceptical of an N = 16 early-stage drug trial for the flu.