Bone marrow from patients with MDS displays increased Ripk1 and pMLKL and necrotic morphology on electron microscopy. (A) Ripk1 staining on paraffin-embedded human bone marrow aspirate for DAPI and Ripk1. MDS subtypes include (from top to bottom) refractory cytopenia with multilineage dysplasia (RCMD), refractory anemia with excess blasts (RAEB-1), and refractory anemia with ring sideroblasts (RARS). Scale bar, 100 μm. The experiment was performed 3 independent times. (B) Phospho-MLKL staining on paraffin-embedded human bone marrow aspirate. The experiment was performed 2 independent times. Scale bar, 50 μm. (C) Table demonstrating positivity of human samples for Ripk1 and pMLKL by subtype. (D) Cleaved caspase-3 staining on paraffin-embedded human bone marrow aspirate. The experiment was performed 3 independent times. Scale bar, 50 μm. (E) TEM of human bone marrow aspirate following RBC lysis from a normal control donor, an early MDS patient, and a RAEB patient. Scale bars, 2 μm; original magnification ×4400. Quantitation of apoptotic or necroptotic cell death for each patient represented in graph (right).