[Effects of Rapamycin and Rapamycin-loaded Poly(lactic-co-glycolic)Acid Nanoparticles on Apoptosis and Expression of bcl-2 and p27(kip1) Proteins of Human Umbilical Arterial Vascular Smooth Muscle Cell].

OBJECTIVE: To investgate the effects of rapamycin(RPM)and RPM-loaded poly(lactic-co-glycolic)acid(PLGA)nanoparticles(NPs)on the apoptosis of human umbilical arterial vascular smooth muscle cells(HUASMCs)in vitro and expression of bcl-2 and p27(kip1) protein. METHODS: HUASMCs were cultured in vitro and divided to RPM and RPM-PLGA-NPs groups treated at 3 different concentration by 12 and 24 hours,with M231-smooth muscle growth supplements medium and null-PLGA-NPs treated groups as controlled. The apoptosis of HUASMCs was determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling staining and flow cytometry. The expressions of bcl-2 and p27(kip1) were detected by streptacidin/peroxidase immunohistochemical method. The effect on cellular proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromidecolorimetry. RESULTS: The proliferation of HUASMCs was inhibited by RPM and RPM-PLGA-NPs in a dose-dependent manner. DNA electrophoresis showed DNA ladder in RPM and RPM-PLGA-NPs groups and classical scalar strips in control groups. The apoptotic indexes of RPM 100 ng/ml group and RPM-PLGA-NPs 500 ng/ml group detected by flow cytometry were(45.45<2.36)% and(35.04<5.64)%,respectively,which were significantly higher than that of M231-smooth muscle growth supplements control group [(2.60<0.95)%,all P<0.01]. The apoptotic indexes of groups incubated with RPM and RPM-PLGA-NPs for 24 hours were significantly higher than those of groups which incubated for 12 hours(P<0.05,P<0.01). The positive expression indexes(PEI)of p27(kip1) and bcl-2 protein were higher in RPM and RPM-PLGA-NPs groups than that of control groups. The Spearman's rank correlation coefficient test showed that there was no significant correlation between the PEI of p27(kip1) and the apoptotic indexes in the RPM group and RPM-PLGA-NPs group(P>0.05). CONCLUSIONS: Rapamycin-loaded PLGA nanoparticles and rapamycin have similar effects in inhibiting proliferation and inducing apoptosis;meanwhile,they upregulate the expression of p27(kip1) protein without downregulating the expression of bcl-2 protein in HUASMCs in vitro. RPM-PLGA-NPs has more potent pro-apoptotic effect than equivalent dose of RPM but is not linearly correlated with the p27(kip1) expression level.

[Facial paralysis induced by herpes simplex virus type 1 and the study of facial neurons apoptosis in mice].

OBJECTIVE: To study the apoptosis of facial motor neurons and the expression of apoptosis-related genes, Bcl-2 and Bax, in the animal model of viral facial paralysis. METHODS: Total of 84 Balb/c mice were divided into viral inoculation group and nerve transaction group. The animals were executed 1, 3, 7, 10, 15, 20 and 30 days after being operated respectively. The histopathological features of facial neurons in brain stem were observed by HE and Nissl stain. The changes of facial neuronal apoptosis were observed by TUNEL. The changes of expression of Bcl-2 and Bax genes in facial neurons were observed by immunohistochemistry staining. RESULTS: After nerve transection, increased apoptotic cells were found in homolateral facial motor nucleus and the peak appeared at 10 and 15 days. The level of Bcl-2 expression in neurons declined while the expression of Bax increased gradually. Correspondingly, the ratio of Bcl-2/Bax declined. In the viral inoculation group, no visible change of apoptosis and Bax expression, but the level of Bcl-2 and the ratio of Bcl-2/Bax increased gradually. CONCLUSIONS: Comparing to axotomy, facial motor nucleus in HSV-1 infective animal model are free of apoptosis. Both the mild form of lesion and the ability to block apoptosis of HSV-1 are likely to be involved into the phenomenon. Bcl-2 and Bax might interfere with the apoptotic response.

Essential role of HDL on endothelial progenitor cell proliferation with PI3K/Akt/cyclin D1 as the signal pathway.

High-density lipoprotein (HDL) is known as an important factor in vascular wall remodeling that also affects gene expression in cell proliferation and differentiation. In this article, the role of HDL on endothelial progenitor cell (EPC) proliferation, angiogenesis and the signal pathway involved was studied, particularly the influence of HDL in strengthening the promoting effect of EPCs on wound healing of the arterial wall in hypercholesterolemic rats. Mononuclear cells isolated from rat bone marrow displayed characteristics of EPCs after cultivation. The role of HDL on EPC function and the signal pathway involved were studied by Western blotting, in vitro migration and 'tube' formation. Re-endothelialization and the number of circulating EPCs were compared between normal rats, hypercholesterolemic rats and hypercholesterolemic rats with HDL treatment. Results showed that HDL participated in the healing process by promoting EPC proliferation, migration and 'tube' formation. HDL activates cyclin D1 via phosphatidylinositol 3-kinase (PI3K)/Akt stimulation. Inhibition of PI3K/Akt via pharmacological or small interfering RNA approaches significantly attenuated HDL-induced EPC migration, proliferation and 'tube' formation. Results of experiments in vivo showed that HDL increased the number of circulating EPCs and promoted re-endothelialization in wound healing. These findings demonstrate for the first time that PI3K/Akt-dependent cyclin D1 activation plays an essential role in HDL-induced EPC proliferation, migration and angiogenesis.

[Effects of rapamycin-loaded poly(lactic-co-glycolic) acid nanoparticles on distribution of cell cycle, expression of p27 protein, and proliferation of human umbilical arterial vascular smooth muscle cell in vitro].

OBJECTIVE: To evaluate the effects of rapamycin (RPM)-loaded poly (lactic-co- glycolic) acid (PLGA) nanoparticles (NPs) on the proliferation, distribution of cell cycle, and expression of p27 protein in human umbilical arterial vascular smooth muscle cell (HUASMC) in vitro. METHODS: The primarily culture model of HUASMC was successfully established by explant-attached method in vitro. The cells were administrated with different doses of RPM, and RPM-PLGA NPs were observed as treat groups compared with PLGA NPs and M231-SMGs medium cultured group. The effect of RPM-PLGA NPs on proliferation of HUASMC was assessed using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colorimetry method. The influences of RPM-PLGA NPs on the cell cycle and cellular growth kinetics of HUASMCs were tested by flow cytometry. The effect of RPM-PLGA NPs on the expression of p27 protein of HUASMCs was assessed through an immunohistochemical method. RESULTS: Compared with the control group, the proliferation of HUASMCs was inhibited by 50 microg/L and higher concentration of RPM-PLGA NPs in a dose-dependent manner (P < 0.05). The numbers of cells entering cell cycle of S/G2/M phases were significantly lower in RPM-PLGA NPs and RPM treated groups. Histologically, the expression of p27 were up-regulated in 500 microg/L RPM-PLGA NPs and 100 microg/L RPM treated group (all P < 0.01 ) when compared with the control group. CONCLUSIONS: RPM-PLGA NPs has a similar effects as RPM in inhibiting the growth of in vitro cultured HUASMC. It can remarkably suppress the expression of in vitro cultured HUASMC p27 protein, arrest its cell cycle at G1/S phase, and inhibit its proliferation.

[The effect of serum high-density lipoprotein on the growth rate of human endothelial progenitor cells].

OBJECTIVE: To study the effect of high-density lipoprotein (HDL) on the proliferation of endothelial progenitor cells (EPC) isolated from human umbilical cord blood; to further explore its effect on prevention and development of atherogenesis. METHODS: EPC isolated by density gradient centrifugation were cultured in a M200 medium. Immunofluorescence staining for CD133, CD34, KDR and Factor VIII were adopted respectively as the specific markers for identification. The effect of HDL on EPC proliferation was estimated on the 7th day of cell cultivation using MTT assay, confocal microscopy and fluorescence activated cell sorting. RESULTS: HDL, when incubated with EPC, was able to promote remarkably the proliferation rate of EPC, dose- and time-dependent. HDL participated in the transcriptional regulation of cell cycle by affecting the regulatory proteins such as cyclin D1. CONCLUSIONS: A subtype of progenitor cells was isolated from human cord blood with a potential of differentiating into mature endothelial cells (known as endothelial progenitor cells). HDL plays an important role on EPC fluorescence activated cell sorting differentiation and proliferation. Further studies are required to identify the signal pathway and the molecular mechanism of HDL effect on EPC proliferation.

Effect of oxidized-LDL on NF-kappaB nuclear translocation in aortic smooth muscle cells originated from rats of different ages.

OBJECTIVE: To investigate the molecular mechanism of atherosclerosis that related to age. METHODS: Immunohistochemistry staining and Western blot were adopted to determine the nuclear translocation of nuclear factor-kappa B (NF-kappaB) and expression of platelet-derived growth factor B (PDGF-B) in smooth muscle cells (SMCs) co-cultured with low density lipoprotein (LDL), oxidized LDL (ox-LDL), and ox-LDL+high density lipoprotein (HDL) originated from rats of 2 and 10 months old respectively. Fat stain was used to identify the lipid intake in SMCs. RESULTS: The optimal stimulation time of ox-LDL to SMCs was 12 hours. NF-kappaB intensity increased in most nuclei of SMCs that originated from rats of either 2 or 10 months old co-cultured with ox-LDL. The intensity of NF-KB and the amount of intracellular lipid taken in SMCs were more obvious in cells from 10-month-old rats than from the younger ones. Change of PDGF-B expression in SMCs was not remarkable in each group of rats. CONCLUSIONS: The 10-month-old rats are more susceptive to ox-LDL than 2-month-old rats in activating nuclear translocation of NF-kappaB. Maybe this is one of the important reasons contributing to the difference between the older and younger rats on the initiation and development of atherosclerosis lesion. Expression of PDGF-B is not associated with the activity of nuclear translocation of NF-kappaB.

An animal model of SARS produced by infection of Macaca mulatta with SARS coronavirus.

A new SARS animal model was established by inoculating SARS coronavirus (SARS-CoV) into rhesus macaques (Macaca mulatta) through the nasal cavity. Pathological pulmonary changes were successively detected on days 5-60 after virus inoculation. All eight animals showed a transient fever 2-3 days after inoculation. Immunological, molecular biological, and pathological studies support the establishment of this SARS animal model. Firstly, SARS-CoV-specific IgGs were detected in the sera of macaques from 11 to 60 days after inoculation. Secondly, SARS-CoV RNA could be detected in pharyngeal swab samples using nested RT-PCR in all infected animals from 5 days after virus inoculation. Finally, histopathological changes of interstitial pneumonia were found in the lungs during the 60 days after viral inoculation: these changes were less marked at later time points, indicating that an active healing process together with resolution of an acute inflammatory response was taking place in these animals. This animal model should provide insight into the mechanisms of SARS-CoV-related pulmonary disease and greatly facilitate the development of vaccines and therapeutics against SARS.

Expression of antisense thrombin receptor gene inhibits intimal hyperplasia of rat carotid artery after balloon injury.

OBJECTIVE: To study the mechanism of restenosis after angioplasty and to clarify the effect of thrombin and its receptor on restenosis development. METHODS: Balloon catheter-induced injury was adopted to induce intimal hyperplasia of the carotid arteries in rats. Antisense thrombin receptor (ATR) cDNA was transfected by perfusing recombinant LXSN ATR plasmid/nanoparticle complex into the segment of the injured carotid artery. RESULTS: PCR result showed integration of the recombined gene. Dot blot showed the expression of antisense TR mediated by recombinant LXSN ATR plasmid/nanoparticle complex in the wall of common carotid arteries of the experimental group rats, which enabled to inhibit TR gene expression and intimal hyperplasia of the injured arteries. CONCLUSIONS: Thrombin and its receptor play an important role in the formation of neointima after the injury, which provides a potential clue in developing a new approach for prevention and treatment of restenosis after angioplasty.