Abcc6−/−Rag1−/− mice at 6 weeks of age received Ad5-CMV-hABCC6 or Ad5-PL-hABCC6 at 4×108 or 1×109 IFU. 8 mice per group. The mice were analyzed 4 weeks after injection, at 10 weeks of age. (a) Upper panel: Administration of 4×108 and 1×109 IFU Ad5-CMV-hABCC6 per mouse did not reveal significant differences in ABCC6 expression (Green). Note negative expression in C57BL/6J un-treated mice and Abcc6−/−Rag1−/− mice receiving Ad5-PL-hABCC6. Scale bar, 0.2 mm. Blue = DAPI. Lower panel: Ectopic mineralization in the dermal sheath of vibrissae (arrows) was analyzed by histopathology with von Kossa stains. Abcc6−/−
Rag1−/− mice treated with Ad5-PL-hABCC6 had similar levels of mineralization in the muzzle skin to that of Abcc6−/−Rag1−/− control mice. In contrast, administration of Ad5-CMV-hABCC6 at 4×108 or 1×109 IFU per mouse revealed only residual mineralization; Scale bar, 0.4 mm. (b) Treatment outcome measures. Upper panel: The chemical assay of calcium demonstrated significant reduction in the amount of calcium in the muzzle skin in the Abcc6−/−Rag1−/− mice treated with Ad5-CMV-hABCC6 at both doses; Lower panel: Increased plasma PPi levels in Abcc6−/−Rag1−/− mice treated with recombinant adenovirus. n = 8 mice per group. *p < 0.05, **p < 0.01, compared to Abcc6−/−Rag1−/− mice. +p < 0.05, ++p < 0.01, compared to C57BL/6J mice.