The Yin and Yang of lactosylceramide metabolism: implications in cell function.

Although lactosylceramide (LacCer) plays a pivotal role in the biosynthesis of nearly all the major glycosphingolipids, its function in regulating cellular function has begun to emerge only recently. Our current opinion is that several physiologically critical molecules such as modified/oxidized LDL, growth factors, pro-inflammatory cytokines and fluid shear stress converge upon and activate lactosylceramide synthase to generate LacCer. In turn, LacCer activates an "oxygen-sensitive" signaling pathway involving superoxides, nitric oxide, p21 Ras GTP loading, kinase cascade, PI3kinase/Akt activation, nuclear factor up-regulation ultimately contributing to phenotypic changes such as cell proliferation, adhesion, migration and angiogenesis. Since dys-regulation of such phenotypic changes constitute a hallmark in several diseases of the cardiovascular system, proliferative disorders such as cancer, polycystic kidney disease and inflammatory diseases, LacCer synthase and LacCer provide novel targets for the development of therapeutics aimed at these health conditions.

Radiofrequency-enhanced vascular gene transduction and expression for intravascular MR imaging-guided therapy: feasibility study in pigs.

PURPOSE: To evaluate the feasibility of radiofrequency (RF)-enhanced vascular gene transduction and expression by using a magnetic resonance (MR) imaging-heating guidewire as an intravascular heating vehicle during MR imaging-guided therapy. MATERIALS AND METHODS: The institutional committee for animal care and use approved the experimental protocol. The study included in vitro evaluation of the use of RF energy to enhance gene transduction and expression in vascular cells, as well as in vivo validation of the feasibility of intravascular MR imaging-guided RF-enhanced vascular gene transduction and expression in pig arteries. For in vitro experiments, approximately 10(4) vascular smooth muscle cells were seeded in each of four chambers of a cell culture plate. Next, 1 mL of a green fluorescent protein gene (gfp)-bearing lentivirus was added to each chamber. Chamber 4 was heated at approximately 41 degrees C for 15 minutes by using an MR imaging-heating guidewire connected to a custom RF generator. At day 6 after transduction, the four chambers were examined and compared at confocal microscopy to determine the efficiency of gfp transduction and expression. For the in vivo experiments, a lentivirus vector bearing a therapeutic gene, vascular endothelial growth factor 165 (VEGF-165), was transferred by using a gene delivery balloon catheter in 18 femoral-iliac arteries (nine artery pairs) in domestic pigs and Yucatan pigs with atherosclerosis. During gene infusion, one femoral-iliac artery in each pig was heated to approximately 41 degrees C with RF energy transferred via the intravascular MR imaging-heating guidewire, while the contralateral artery was not heated (control condition). At day 6, the 18 arteries were harvested for quantitative Western blot analysis to compare VEGF-165 transduction and expression efficiency between RF-heated and nonheated arterial groups. RESULTS: Confocal microscopy showed gfp expression in chamber 4 that was 293% the level of expression in chamber 1 (49.6% +/- 25.8 vs 16.8% +/- 8.0). Results of Western blot analysis showed VEGF-165 expression for normal arteries in the RF-heated group that was 300% the level of expression in the nonheated group (70.4 arbitrary units [au] +/- 107.1 vs 23.5 au +/- 29.8), and, for atherosclerotic arteries in the RF-heated group, 986% the level in the nonheated group (129.2 au +/- 100.3 vs 13.1 au +/- 4.9). CONCLUSION: Simultaneous monitoring and enhancement of vascular gene delivery and expression is feasible with the MR imaging-heating guidewire.