This paper nicely confirms and expands on our own observation that recombinant fibrils of tau are sufficient to accelerate tau propagation in vivo (Wu et al., 2012). Injecting recombinant tau rather than tau derived from a brain extract has helped clarify our understanding of the nature of the seeding agent, confirming that tau fibrils alone are sufficient to accelerate propagation, and not some co-factor present in brain extract. It is still a mystery, however, why the injection models fail to develop tangle-related gliosis and degeneration seen in humans with FTLD-tau, or in mouse models with endogenously generated tauopathy. We still need to validate the physiological relevance of the injection approach.

References:
Wu JW, Herman M, Liu L, Simoes S, Acker CM, Figueroa H, Steinberg JI, Margittai M, Kayed R, Zurzolo C, Di Paolo G, Duff KE. Small misfolded tau species are internalized via bulk endocytosis and anterogradely and retrogradely transported in neurons. J Biol Chem. 2012 Nov 27. Abstract

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