Acquisition of murine and human blood samples
Blood from 129Sv wild type and annexin A7 knock out mice (anxA7-/-) kept under pathogen-free conditions and fed with regular food, was collected in 1 ml syringes with a 22 gauge needle punctating the right cardiac ventricle immediately after they had been killed by cervical dislocation. Coagulation generally was inhibited with 1/10 volume of 10 mM NaEDTA, pH 7.5, already present in the syringe. The mice were killed by cervical dislocation in order to avoid any effect of anaesthetic chemicals on blood parameters. The wild type and mutant mice were matched regarding their age, weight and sex. The daytime of blood collection, sampling site and collection method were kept constant during all experiments. A typical murine blood sample volume consisted of 550 μl, with variations ranging from 200 μl to 900 μl. Human blood samples from the authors were collected by vein puncture using common EDTA-monovettes (Sarstedt).
We performed our studies using well standardized sampling conditions, as differences in the blood sampling site, for example between tail and heart, show large changes in all cell type counts. First and second sample draw affect blood measurements, too [22]. Also the genetic background in common laboratory and transgenic mice affects the phenotype. A change from one strain to another may protect mice from effects of the primarily induced genetic defect. For example, BALB/c mice have a significantly increased velocity of platelet aggregation as compared to 129Sv mice, which were used throughout this study [23].