Study Of Proliferation And Apoptosis About VSMC After Balloon Injury Treated With Rapamycin In Rats

Background Intervention treatment is a magnitude thchnique of imsurgical treatment to CHD. PTC A is a effective and conveniency method to treat CHD and has become an integral and important part of cardiology scince its beginnings in the late 1970s. It has been widly used in more than one hundred countries. But their long-term successes are significantly limited by high rate of restenosis. The restenosis problem remains perplexing and recalcitrant and both the clinic and laboratory operator are very concerned of it. Several mechanisms have been implicated in the development of restenosis post-injury: Flexibility shrink of the vascular-, Form and hypothyroidof the thrombus; Activation of migration and proliferation of the vascular smooth muscle cell (VSMC). Extracellular cell and basement membranes degradation are premising Condition for VSMC migration. VSMC proliferation make a important action on restenosis. VSMC can proliferation and migration after balloon injury with similation of damnification and growth factors. Apoptosis of VSMC after balloon injury also has some relationship with restenosis. Both the clinical observation and experimental study display that p 27Kipl and rapamycin can restrain the cell proliferation.P 27Klpl is a kind of cyclin dependnt kinase inhibitor (CKI) and it can regulate cell cycle through restraining cyclin and cyclin dependnt kinase (CDK). P 27 gene has three main protein forms: P 27kipl, P 27Ick, P 27pic2, and P27kip1 is the most familiar form of all. P27Kipl restrains the proliferation of VSMC obviously and is prospective to become a new means to cure restenosis after PTCA.As a kind of immunosuppressor rapamycin can control proliferation through regulation on cell cycle. It has been substantiated to control the downregulation of P27Klpl both in vitro and in vivo. But the relationship about proliferation and apoptosis of VSMC and the idiographic mechanism about rapamycin are still unkown.Cellular apoptosis is a process that cell follow procedure of it's own to end itself in definite physical or pathological condition. There is apoptosis of VSMC after balloon injury, but the apperence time and degree of apoptosis are still not consistent.Objective The aims of current study were to examin relationship between P 27Klpl level and multiplication degee and the effect on restenosis with administration of rapamycin with a balloon jniury model.Methods All studies were performed on one hundred and fifty healthy adult male rats (SD) which were randomized divided into four groups: 1. Sham operation group (n=20) Separated and ligated common carotid artery only. 2. Balloon injury group (n=40): Received balloon injury only. 3. Sodium carboxymethyl cellulose (SCC) group (n=40): Administration with 0.2% sodium carboxymethyl cellulose noly. 4. Rapamycin group (n=40):Administration with rapamycin (suspended in solution containing 0.2% sodium carboxymethyl cellulose) started 3 days before injury at a dose of 0.5 mg/kg and continued for 14 days at a dose of 0.25 mg/kg.Rats were harvested at 3days, 7 days, 14 days, 21 days and 28 days after injury. Abdominal aortas were analyzed for intimal area, mean intimal thickness and intimal/media area ratio. PCNA and a -Actin within the vessel wall were determined by immmunohischemistry stain. P 27Klpl level were mensurated by western-blot and FCM. Cell cycle , cyclinE and CDK2 were determined by flow cytometry. Blood lipid, renal function, white blood cells and body weight were inspected.Results 1. Rats' endodermis cells were exfoliated from blood vessel and inner elasticity shutter was destoried and ruptured after balloon injury. VSMCs has proliferated from the 7th day and attained pinnacle in the 14th day. Neointimal area and intimal/media area ratio 14 days after injury showed a 36.4% and 28.9% reduced in the animals receiving rapamycin compared with contoals respectively (0.14 ± 0.03 mm2 vs 0.23±0.06mm2 and 17.70 ± 3.37% vs 28.86±10.25%, respectively, P<0.01). Nuclear cell counts were lower in intima of rapamycin-treated a...