The data presented by Huard and colleagues are complementary to the report by Villeda et al. in that they’re studying the effects of young cells in progeria, while Wyss-Coray's team studied effects of young blood plasma in healthy aging.

I am not sure how these cell transplants could affect brain vasculature via soluble factors in regions shielded by the blood-brain barrier (such as the cortex). Measurements of vascular density in brain are notoriously difficult and need really to be done by stereology. Also, some functional readout correlating with more vessels would be informative.

Potential therapeutic application would depend on having the ability to obtain young histocompatible cells (or the equivalent such as isogenic induced pluripotent stem cells) and show that they’d ameliorate the outcomes of aging or age-related neurodegeneration.

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