M1-MΦs and M2-MΦs have opposite effects on HSC self-renewal and expansion in vitro. (A) Diagram illustrating the design of the experiments in panel B, in which mouse BM LSK cells were cultured with sorted mouse BM CD115⁺Gr-1^high Mos (Gr-1^high Mo), CD115⁺Gr-1^low Mos (Gr-1^low Mo), or CD115⁻Gr-1^lowF4/80⁺SSC^low MΦs (MΦ). (B) Numbers of total cells, LSK cells, and 5-week CAFCs in the input LSK cells and the progeny from various cultures shown in panel A. ^aP < .05 vs Input, ^bP < .05 vs Input and without MΦs (W/O MΦ), ^cP < .05 vs all other groups, ^dP < .05 vs all other groups except Input. (C) Diagram illustrating the design of the experiments in panel D. MΦs were isolated from mouse BM (BM-MΦs) or peritoneal cavity (P-MΦ). (D) Numbers of total cells, LSK cells, and 5-week CAFCs in the input LSK cells and the progeny from various cultures shown in panel C. ^aP < .05 vs W/O MΦ, ^bP < .05 vs Input and W/O MΦ, ^cP < .05 vs all other groups. (E) Diagram illustrating the experimental design for peritoneal MΦ polarization and LSK cell cocultures. (F) Relative gene expression in M1-MΦs and M2-MΦs compared with MΦs analyzed by quantitative polymerase chain reaction. *P < .05, **P < .01, and ***P < .001 vs cells cultured with M1-MFs; unpaired Student t test. (G) Arg1 activity in MΦs, M1-MΦs, and M2-MΦs. ^aP < .05 vs MΦ, ^bP < .05 vs MΦ and M1-MΦ. (H) Numbers of total cells, LSK cells, and 5-week CAFCs in the input LSK cells and the progeny from various cultures shown in panel E. ^aP < .05 vs Input, ^bP < .05 vs MΦ, ^cP < .05 vs Input and W/O MΦ, ^dP < .05 vs Input, W/O MΦ, and MΦ, ^eP < .05 vs all other groups, ^fP < .05 vs all other groups except MΦs. All data are mean ± standard error of the mean (SEM) (n = 3 independent cultures) and were analyzed by 1-way analysis of variance (ANOVA).