Pharmacokinetics of transplacental passage of AMD3100 and firategrast and fetal HSC mobilization. (A) Firategrast (100 mg/kg, intravenous) or (B) AMD3100 (5 mg/kg, subcutaneous) was maternally administered to E17 Balb/c dams, and the concentration of the mobilizing agent in ∼100 μL maternal (n = 3 per time point) and fetal (n = 4-5 per time point) serum was determined at 15, 45, 90, and 180 minutes after treatment by mass spectrometry by spiking the serum with either deuterated-AMD3100 (AMD3100 analysis) or reserpine (firategrast analysis). To obtain an adequate volume of fetal serum for analysis, pharmacokinetics was performed at E17, and each fetal sample consisted of blood pooled from 4 to 5 fetuses obtained by fetal decapitation. (C) Mobilization of endogenous HSCs from the FL was determined after administering AMD3100 and/or firategrast to E14 Balb/c dams. FLs were harvested 60 minutes after treatment, and the absolute number of lineage− (CD3−B220−Gr1−Ter119−) Sca-1+c-Kit+ cells per FL was determined based on the average total number of LDMCs per FL of 3.5 × 105. *P < .05 vs vehicle.
