Pharmacological inhibition of heparan sulfate proteoglycans induces HSPC mobilization. (A) Schematic overview of experimental design. (B) Peripheral WBC counts in C57BL/6J (CD45.2) mice receiving G-CSF or G-CSF plus heparin. (C) Total donor (CD45.2) reconstitution of G-CSF or G-CSF plus heparin mobilized PB from C57BL/6J (CD45.2) transplanted into lethally irradiated CD45.1 congenic recipients. CD45.1 BM cells were transplanted for radioprotection in equal numbers in both groups. The break in the X-axis represents serial BM transplantation into lethally irradiated recipients. (D-F) Clustering of genes differentially expressed in fluorescence-activated cell sorter sorted HSPCs (Lin⁻, cKit⁺, Sca1⁺) from PB upon G-CSF (n = 1) or G-CSF plus heparin (n = 2) induced mobilization showing changes in (D) cell adhesion genes, (E) cell proliferation genes, and (F) growth regulation genes. Blue and yellow represent higher and lower expression, respectively. (G-H) Noncompetitive transplantation of G-CSF or G-CSF plus heparin mobilized PB into lethally irradiated recipients showing (G) neutrophil and (H) platelet recovery. Gray shadowed area represents the window of time in which the recovery time differed between groups. (I) Total donor (CD45.2) reconstitution of G-CSF or G-CSF plus heparin mobilized PB from Ext1 mutant mice transplanted into lethally irradiated CD45.1 congenic recipients. CD45.1 BM cells were transplanted for radioprotection in equal numbers in both groups. (J) Relative PB reconstitution, 16 weeks after transplantation, of recipient CD45.1 mice transfused with PB from C57BL/6J mice (CD45.2) receiving G-CSF and heparin or G-SCF and hirudin. Recipient mice were lethally irradiated and received CD45.1 cells for radioprotection. (K-L) Ext1/heparan sulfate genetic deletion and pharmacological inhibition rescue type 1 diabetes-induced mobilopathy. Relative PB reconstitution, 16 weeks after transplantation, of recipient mice transfused with (K) G-CSF mobilized PB from nondiabetic and diabetic control and mutant mice (4 groups in total) or (L) G-CSF plus heparin mobilized PB from nondiabetic and diabetic C57BL/6J mice. For the transplants, lethally irradiated CD45.1 animals were used as recipients. CD45.1 BM was used in equal numbers for radioprotection. Data are representative of at least 2 independent experiments; n = 5 to 8 mice per genotype per experiment. In mobilization experiments, PB was collected from at least 5 mice per experimental group. Data are represented as mean ± SD or median ± interquartile range. *P < .05; **P < .01; ***P < .001.