Figure 2.

Heterogeneous impact of adoptive transfer of CD4+ T_Reg on bone healing outcome in mice kept under non-SPF housing conditions. (A–D) μCT evaluation of the healing outcome after adoptive CD4+ T_Reg transfer after 21 d. (A) Representative images of the analyzed volume of interest of the healing bones are shown. +T_Reg treated mice clustered into responder (+T_Reg left, n = 4) and non-responder (+T_Reg right, n = 4). Control mice showed no complete bridging after 21 d (left, control, n = 6). In contrast, +T_Reg responder showed complete bridging, whereas non-responder showed no bridging. (B–D) Quantification of the μCT analysis, + T_Reg responder vs. + T_Reg non-responder vs. control mice. (E–G) Evaluation of the immune cell composition of +T_Reg responder vs. non-responder 21 d post-surgery. (E) Confirmation of CD4+ T_Reg engraftment in both, +T_Reg responder and non-responder compared to the control. (F,G) +T_Reg non-responder showed an elevated percentage of CD8+ T_EFF (F) as well as a significantly higher ratio of CD8+ T_EFF /CD4+ T_Reg (G) in the peripheral blood in comparison to the +T_Reg responder. TV, total volume; BV, bone volume; BV/TV, ratio of BV to TV; Mann–Whitney U-test, Bonferroni correction (B–E).