Figure 4.

Xenografts are functionally competent. (A) Xenograft explants were suspended in a temperature-controlled, physiological saline contained bath and electrically evoked force measurements were recorded with 250 ms trains of pulses delivered between 1 and 300 Hz. Representative isometric force traces are shown normalized to the calculated CSA of the xenograft. (B) Force-frequency relationship of aggregate data from three xenografts derived from three healthy donors. (C) Single enzymatically isolated myofiber from xenograft identified post-physiology as human with immunohistochemistry using anti-human spectrin (red), anti-human lamin A/C (green) antibodies and DAPI (blue). (D) Single myofibers were loaded with the ratiometric calcium (Ca²⁺) dye Indo-1-PE and electrically stimulated to elicit calcium transients. Representative twitch (single square 0.2 µs square field pulses, black trace) or tetanic trains (100 Hz, purple trace) are shown from fibers isolated from xenograft explants (n = 3) of healthy donors. (E) Aggregate Ca²⁺ transient data (Box whisker plot; box = 5–95%; line = population median; whiskers = min/max).