Description of Research Expertise

Research Interests:
Drug/gene targeting and vascular biology

Particular areas of interest/expertise include the recognition of surface antigens on normal or pathologically altered endothelial cells; vascular inflammation and leukocytes adhesion; mechanisms of oxidative stress and antioxidant protection of the endothelium; evaluation of specific markers of endothelial injury; immunotargeting of antioxidant enzymes, fibrinolytics and genes to the pulmonary endothelium; pulmonary pathophysiology; lung ischemia/reperfusion; prolongation of enzymes life-time in the bloodstream; controlled elimination of radiolabeled antibodies or pathogens from the bloodstream; exploration of red blood cells as carriers for prolonged circulation and site-specific delivery of drugs (fibrinolytics and anticoagulants); regulation of fibrinolysis and complement; mechanisms and regulation of intracellular targeting/trafficking of drugs.

Research Summary
The laboratory is focused on several projects. First is the targeting of drugs (enzymes either degrading or generating oxidants, fibrinolytics, interferon, antisense oligos and genes) to the pulmonary vascular endothelium. The purpose is to develop strategies for controlled site-specific delivery of a drug to the defined subcellular compartments of the pulmonary endothelium. For example, genetic material must be delivered into the nucleus, antioxidants must accumulate in the cytoplasm, and fibrinolytics must avoid internalization. We therefore study how carrier antibodies and their derivatives recognize endothelium, and characterize cellular trafficking and local effects of the targeted agents in cell cultures, perfused animal lungs and in intact animals. Our research includes identification of the molecules localized on the surface of endothelium useful as targets for drug delivery to either normal or pathologically challenged endothelium. Endothelium-specific antigens may serve as such targets. Affinity carriers that are currently explored in our laboratory include monoclonal antibodies (and their fragments) to: angiotensin-converting enzyme (ACE), thrombomodulin and surface adhesion molecules, ICAM, PECAM, P- and E-selectins. We have characterized carriers and their modifications providing: i) a drug with an affinity to endothelium (recognition and targeting) and, ii) drug delivery in a proper cellular compartment (sub-cellular addressing). Targeting to either surface (by non-internalizable carriers) or intracellularly has been documented in cell culture, perfused lungs and in rodents in vivo.

Secondly, we explore red blood cells (RBC) as natural carriers for drugs. We have developed an original methodology for effective conjugation of large amounts of a drug (e.g., fibrinoytic enzymes or receptors for plasminogen activators) on RBC, without loss of biocompatibility of the complex. Conjugation provides prolongation of half-life of plasminogen activators in vivo by orders of magnitude and offers specific transfer of the conjugated protein (tPA, uPA-receptor) to the pulmonary endothelium. Both mechanism of the transfer (tentatively via exchange of GPI-anchored membrane proteins between RBC and endothelium) and potential therapeutic applications of RBC-conjugated fibrinolytics (treatment/prevention of pulmonary embolism/deep vein thrombosis) are in the focus of the research. We also explore RBC as carriers for intracellular drug delivery in phagocyte cells in the reticuloendothelial tissue (liver and spleen) and endothelial cells.