Fig. 6.

Chimeric mouse studies demonstrate that hematopoietic and structural sources of periostin promote fibrosis. Chimeric mice were created by transplantation of C57Bl/6 marrow into C57Bl/6 recipients (B6→B6) or periostin^−/− recipients (B6→KO). Complementary chimeras were created by transplantation of KO→B6 or KO→KO. Chimeric mice were then treated with saline (n = 3/group) or bleomycin (BLM; n = 5/group), and hydroxyproline analyses were done at day 21. There was no statistically significant difference between any of the groups of saline-treated mice. Sal, data for all groups treated with saline. As expected, B6→B6 chimeras developed a significant increase in lung collagen content over saline-treated mice. Collagen contents in B6→KO and KO→B6 chimeras were similar to those in protected KO→KO mice. *P < 0.05, **P < 0.01, ***P < 0.001.