Bone Marrow Labeling by Microinjection

Bone marrow tagging by microinjection were performed as previously described^{29 (link)}. Microinjection of the tibia marrow was performed sequentially under 0.3% pentobarbital anesthesia, using a 1 ml syringe mounted with a 5 mm-outer-diameter veterinary needle. For each procedure aseptic technique was used. For the tibia marrow injection, we injected at the chosen injection site of tibia plateau just below the knee and the bone wall was perforated with a veterinary needle. The red cell tracker or CXCL1/2 antibodies (Clone # 48415, R&D Systems, MAB453, 0.2 μg/ml or 5 ng/mice once; Clone # 40605, R&D Systems, MAB452, 2 μg/ml or 40 ng/mice once) was injected in the marrow cavity over 30 s. Animals were sacrificed 12 h after injection.