Kindlin-3 regulates HSPC homeostasis in an integrin-dependent manner. (A) Relative mean fluorescence intensity of 9EG7 binding on BM LSK CD150⁻CD48⁺ and LSK CD150⁺CD48⁻ cells from chimeras. Error bars indicate geometric mean fluorescence intensity (MFI) ± SD. **, P < 0.01 by paired t test. n = 3 per genotype; two independent experiments. (B) Kaplan-Meier survival curve of lethally irradiated recipients transplanted with LSK cells transduced with lentiviral expression constructs as indicated together with WBM cells from a K3^−/− 100% chimera. ***, P < 0.0001 by log-rank test. n = 9–10 recipients per group; two independent experiments. (C) Mean percentages ± SD of donor-derived whole leukocytes (CD45⁺), myeloid cells (Gr-1⁺, Mac-1⁺, and Gr-1⁺Mac-1⁺), B cells (B220⁺), and T cells (CD3e⁺) in PB from a WT C57BL/6 mouse (wt-Bl6), recipients of K3^+/+ LSK cells transduced with a GFP expression construct (K3^+/+-GFP; n = 5), recipients of K3^−/− LSK cells transduced with a K3-WT expression construct (K3^−/−-K3^wt; n = 4), and a single surviving recipient of K3^−/− LSK cells transduced with a K3-QWAA expression construct (K3^−/−-K3^mut) 3 mo after transplantation. Two independent experiments. (D) FACS plots of PB from a LAD-III patient and an age-matched healthy child. Shown are MNCs gated for CD34 against CD45 and CD38 against CD34. The blue boxes depict the CD45⁺CD34⁺ cells (left), CD38⁺CD34⁺ cells (top right), and CD38⁻CD34⁺ cells (bottom right). The numbers indicate the percentage of gated cells. (E) CFU assay with PB MNCs containing 100 CD34⁺ cells (calculated according to the FACS frequencies) from a LAD-III patient and an age-matched healthy child. Shown are the numbers of colonies per blood MNC containing 100 CD34⁺ cells. BFU-E, burst forming unit–erythroid; CFU-GM, CFU-granulocyte/macrophage; wt, wild type.