3E). Line scanning with high temporal resolution (2-4 ms) showed that intracellular Ca2+ wave propagation was significantly faster in human astrocytes than murine cells; intracellular Ca2+ increases propagated with a velocity of 15.8 ± 0.7 μm/s among human glia, compared to 5.7 ± 0.4 μm/s in resident murine astrocytes (n=22-34, 6.5 ± 0.4 vs. 7.0 ± 0.5 months-old, mean ± SEM; p<0.05, Steel-Dwass test) (Fig. 3F-H). To determine whether the faster intracellular Ca2+ waves in human astrocytes were an artifact of xenograft, we also assessed intracellular Ca2+ wave spread in slices of fresh human brain tissue, obtained at surgical resection for distant lesions (mean age of patients: 30.6 ± 8.8 years, n = 3). Human astrocytes in these surgical resections similarly propagated intracellular Ca2+ waves much more rapidly than did murine astrocytes (n=10) (Fig. 3H). Together, these experiments demonstrated that intracellular Ca2+ signals propagate at least 3-fold faster within human astrocytes than in their rodent counterparts, and do so in human glial chimeric mice just as in human brain tissue. Of note, we were unable to evaluate intercellular Ca2+ wave propagation, as only slices prepared from young mice pups load well with esterified (AM) Ca2+ indicators (Dawitz et al., 2011).
