Study overview. (A-B) Potential models for circulatory clearance of donor RBCs as a function of cell deformability. If circulatory clearance is independent of deformability, then the deformability distribution of circulating cells remains unchanged (A). If circulatory clearance is dependent on cell deformability, the more rigid cells are preferentially removed (B). (C) The microfluidic ratchet device sorts RBCs based on deformability. Cells are typically distributed between outlets 2 and 5. (D-F) Experimental plan. Mouse RBCs are chemically treated using AMT to alter their deformability distribution relative to the control (D). Both control and AMT-treated cells are labeled with long-lasting fluorescent dyes and transfected into recipient mice (D-E). RBCs sampled from recipients are sorted using a microfluidic ratchet device to concurrently measure the deformability distribution of control donor RBCs, AMT-treated donor RBCs, and endogenous RBCs circulating in the recipient mice (F). Ctrl, control.