Figure 2. Platelet count in OIR and proof of concept.

(A) Scheme of oxygen-induced retinopathy (OIR): C57BL/6 mouse pups are exposed to 75% oxygen from P7–P12 to induce retinal vessel loss and are returned to room air at P12–P17. Below the scheme, 2 representative retinal whole-mount images, including magnification area, from normoxia and OIR P17 pups stained with lectin (see magnification below). P17 OIR pups have pathologic neovascularization compared with normoxia pups. (B) Platelet counts in mouse pups at P7, P12, and P17 with (red) (n = 10) or without (blue) (n = 6) OIR. Platelet count was reduced at P17 OIR (P = 0.0084). (C) Platelet counts were measured in whole blood after 0, 2, and 48 hours after anti-GPIbα antibody injection. A significant decrease in platelet count was seen at 2 and 48 hours after platelet depletion (P = 0.0029 and P < 0.0001). (D) Platelet transfusion proof of concept. WT neonatal mice were retro-orbitally transfused with 10 μl per gram of mouse of 5.0 × 10⁶ platelets/μl. Total platelet counts were measured before transfusion (time 0), as well as 2 and 48 hours after transfusion. The platelet count increased by 42.3% after 2 hours (P = 0.0012). The initial increase was cleared by 58.6% after 48 hours but was still significantly increased compared with time 0 (P = 0.0093). Data represent mean ± SD. Two-tailed unpaired t test.