Harnessing CXCR4 antagonists in stem cell mobilization, HIV infection, ischemic diseases, and oncology.

CXCR4 antagonists (e.g., PlerixaforTM ) have been successfully validated as stem cell mobilizers for peripheral blood stem cell transplantation. Applications of the CXCR4 antagonists have heralded the era of cell-based therapy and opened a potential therapeutic horizon for many unmet medical needs such as kidney injury, ischemic stroke, cancer, and myocardial infarction. In this review, we first introduce the central role of CXCR4 in diverse cellular signaling pathways and discuss its involvement in several disease progressions. We then highlight the molecular design and optimization strategies for targeting CXCR4 from a large number of case studies, concluding that polyamines are the preferred CXCR4-binding ligands compared to other structural options, presumably by mimicking the highly positively charged natural ligand CXCL12. These results could be further justified with computer-aided docking into the CXCR4 crystal structure wherein both major and minor subpockets of the binding cavity are considered functionally important. Finally, from the clinical point of view, CXCR4 antagonists could mobilize hematopoietic stem/progenitor cells with long-term repopulating capacity to the peripheral blood, promising to replace surgically obtained bone marrow cells as a preferred source for stem cell transplantation.

CXCR4 Antagonist TG-0054 Mobilizes Mesenchymal Stem Cells, Attenuates Inflammation, and Preserves Cardiac Systolic Function in a Porcine Model of Myocardial Infarction.

Interaction between chemokine stromal cell-derived factor 1 and the CXC chemokine receptor 4 (CXCR4) governs the sequestration and mobilization of bone marrow stem cells. We investigated the therapeutic potential of TG-0054, a novel CXCR4 antagonist, in attenuating cardiac dysfunction after myocardial infarction (MI). In miniature pigs (minipigs), TG-0054 mobilized CD34(+)CXCR4(+), CD133(+)CXCR4(+), and CD271(+)CXCR4(+) cells into peripheral circulation. After isolation and expansion, TG-0054-mobilized CD271(+) cells were proved to be mesenchymal stem cells (designated CD271-MSCs) since they had trilineage differentiation potential, surface markers of MSCs, and immunosuppressive effects on allogeneic lymphocyte proliferation. MI was induced in 22 minipigs using balloon occlusion of the left anterior descending coronary artery, followed by intravenous injections of 2.85 mg/kg of TG-0054 or saline at 3 days and 7 days post-MI. Serial MRI analyses revealed that TG-0054 treatment prevented left ventricular (LV) dysfunction at 12 weeks after MI (change of LV ejection fraction from baseline, -1.0 ± 6.2% in the TG-0054 group versus -7.9 ± 5.8% in the controls). The preserved cardiac function was accompanied by a significant decrease in the myocardial expression of TNF-α, IL-1ß, and IL-6 at 7 days post-MI. Moreover, the plasma levels of TNF-α, IL-1ß, and IL-6 were persistently suppressed by the TG-0054 treatment. Infusion of TG-0054-mobilized CD271-MSCs reduced both myocardial and plasma cytokine levels in a pattern, which is temporally correlated with TG-0054 treatment. This study demonstrated that TG-0054 improves the impaired LV contractility following MI, at least in part, by mobilizing MSCs to attenuate the postinfarction inflammation. This insight may facilitate exploring novel stem cell-based therapy for treating post-MI heart failure.

Tissue plasminogen activator induced by dengue virus infection of human endothelial cells.

Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS) are severe complications of dengue virus (DV) infection. However, the pathogenesis of hemorrhage induced by dengue virus infection is poorly understood. Since endothelial cells play a pivotal role in the regulation of hemostasis, we studied the effect of DV infection on the production of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) in vitro using both primary isolated endothelial cells, human umbilical cord veins cells, and a human microvascular endothelial cell line. DV infection significantly induced the secretion of tPA but not PAI-1 of human endothelial cells. In addition, tPA mRNA of endothelial cells was induced by DV as demonstrated by RT-PCR. Antibody against IL-6 but not control antibody inhibited DV-induced tPA production of endothelial cells. Furthermore, a good correlation between sera levels of IL-6 and tPA was found in DHF but not DF patients. These results suggest that IL-6 can regulate DV-induced tPA production of endothelial cells, which may play important roles in the pathogenic development of DHF/DSS.