| OBJECTIVE: The restenosis is one of the most importent problem which is steel unsovled in the cardiovascular field, though a lot of work on restenosis have been finished. There are no effective method of reducing or curing restenosis can be used now. In the last decade, apoptosis (or programmed cell death) has become appreciated as an important process in the death of cells, it contributes to the maintaining of cell blance. Based on our previously study, we observed that, after the stent implantation, many of apoptotic smooth muscle cells appeared while the hyperplisia of neointima started, This phenomenon implicated that induced the apoptosis of smooth muscle cells might contribute to reduce the restenosis. Heating, as a physical stimulating factor, could induce apoptosis or necrosis of cells. After heating the stent by non-invasive method was realized, we studied the Hyperthermic influence on the cultured smooth muscle cells of rabbit, to clarify the heating temperature range and duration of inducing apoptosis, to discover the apoptotic pathway, mechanism and expression of genes. Those understanding may form the key theory to implement apoptosis in preventing and curing restenosis after stent implantation.Methods: The SMCs were cultured and heated at temperature of 37"C> 40T:, 42t\ 44t\ 461\ 48t\ 50'C\ 52"C. 54'C, lasted for 10 min, than cultured for 10 hours, 24 hours, 48 hours and 72 hours, the following items were measured: (1) Morphology of SMCs was observed using microscopy; (2)The livingness of SMCs was detected by trypan blue; (3) The ultrastructure changes of SMCs was observed by electro-microscopy and scan-microscopy. (4) Phosphatidylserine (PS) exposure on the outside of the SMCs was measured by annexin V binding kit (5) Phosphatidylserine (PS) exposure was also measured by flow-cytometric analysis; (6) The expression of caspase-3 protein was measured by caspase-3 kit; (7) Apoptosis has been assessed by laddering of genomic DMA; (8)DNA chip technology had been used to analysis the expression of genes. Results: The morphology and living status of SMCs were not interfered with the temperature less than 44'C degreed centigrade, compared with the controls. In the temperature of 46"C\ 48"C-.350, after culture for 10 hours, the SMCs shrinked in rotundity and ellipse, cell taken the shape of string of beads; after 24 hours of culture, all the cells were changed as description above. And a large amount of SMCs fallen off into culture solution. In the temperatures of 52 and 54"C, after culture for 10 hours, shrinking of cells were not occurred, but the edge of cells turned up, then the cells fallen off into culture solution, The shape of shrinking was not observed , they taken the shape of piece. The cells fallen off into the culture solution reached the maximum between 12-24 hours. In the temperature of 46, 48 and 50, the fallen off cells were much more than that of at 44 , but these cells were not painted with trypan blue, it was indicated that the cells were still alive, In the temperature more than 50*C, all the cells were painted with trypan blue, combine with morphologic changes, they were died (necrosis). (2) In the control group, annexin V binding could not be detected, a few annexin V+ cells appeared in the cells heated at temperature of 44 and 46; At 52 group, the SMCs were stained into red color, o both intact cells and to apoptotic bodies. When they first appeared, the intact had S-phase DNA content. Annexin V binding to SMCs were not detected by flow-cytometric analysis. (3) In the groups of 44, 46 and 48'C, the caspase-3 activation was slight high than that of the control and 52 groups, the highest value was in the group of 46 heated at 46 , lasted for 10 min, then culture for 10 hours; The caspase-3 activation was lower than the control group , when the cells were culture for 24 hours. (4) In the groups of 44 and 46C, lasted for 10 min, then culture for 10 hours, DNA ladder were detected, smear bind was detected in 52*C group. (5) In the group of 46 ultrastructural alterations show...
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