[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.

Biological behaviour and role of endothelial progenitor cells in vascular diseases.

OBJECTIVE: To review the biological behaviour of endothelial progenitor cells and their role in vascular diseases. Data sources The data used in this review were mainly from Medline and PubMed for relevant English language articles published from 1985 to March 2007. The search term was "endothelial progenitor cells". Study selection Articles about the biological behaviour of endothelial progenitor cells and their roles in the pathogenesis of vascular diseases such as atherogenesis were used. RESULTS: Progenitor cells in bone marrow, peripheral blood and adventitia can differentiate into mature endothelial cells (ECs). The progenitor cells, which express certain surface markers including AC133, CD34 and KDR, enable restoration of the microcirculation and ECs when injury or ischaemia occurs. Endothelial progenitor cells used in experimental models and clinical trials for ischaemic syndromes could restore endothelial integrity and inhibit neointima development. Moreover, their number and functional properties are influenced by certain cytokines and atherosclerotic risk factors. Impairment of the progenitor cells might limit the regenerative capacity, even lead to the development of atherosclerosis or other vascular diseases. CONCLUSIONS: Endothelial progenitor cells have a particular role in prevention and treatment of certain cardiovascular diseases. However, many challenges remain in understanding differentiation of endothelial progenitor cells, their mobilization and revascularization.

[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.

Effects of oxidized low density lipoprotein on the growth of human artery smooth muscle cells.

BACKGROUND: Studies have shown that oxidized low density lipoprotein (ox-LDL) promotes the pathogenesis and development of atherosclerosis (AS), and that the proliferation, migration and phenotype alteration of vascular smooth muscle cells (vSMCs) into foam cells are critical changes in AS. It is proposed that ox-LDL might play a novel role in the pathologic process of vSMCs. The present study was performed ex vivo to investigate the effects of ox-LDL on the growth of cultured human vSMCs. METHODS: Using NaBr density gradient centrifugation, LDL from human plasma was isolated and purified. ox-LDL was produced from LDL after being incubated with CuSO4. ox-LDL was then added to the culture medium at different concentrations (25 microg/ml, 50 microg/ml, 75 microg/ml, 100 microg/ml, 125 microg/ml, and 150 microg/ml) for 7 days. The influence of ox-LDL on vSMC growth was observed from several aspects as growth curve, mitosis index, lipid staining, and in situ determination of apoptosis. The digital results were analyzed with SPSS 10.0. RESULTS: The ox-LDL produced ex vivo had a good purity and optimal oxidative degree, which was similar to the intrinsic ox-LDL in atherosclerotic plaque. ox-LDL at a concentration of 25 microg/ml demonstrated the strongest proliferation. At the concentration of 125 microg/ml, ox-LDL suppressed the growth of vSMCs. At concentrations of 25 microg/ml and 50 microg/ml, ox-LDL presented powerful mitotic trigger. When the concentration of ox-LDL increased, the mitotic index of vSMCs decreased gradually. ox-LDL induced more foam cells from vSMCs with rich intracellular lipid accumulation at concentrations of 25 microg/ml and 50 microg/ml. ox-LDL at higher concentrations induced more apoptotic vSMCs. CONCLUSIONS: ox-LDL at lower concentrations may trigger proliferation and phenotype alteration into foam cells of vSMCs, and at higher concentrations it may induce apoptosis in vSMCs. ox-LDL plays an important role in the pathogenesis and development of atherosclerosis by its effect on vSMCs proliferation, phenotype alteration and apoptosis.

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.

[Detection of NF-kappaB activation and platelet-derived growth factor-B expression in endothelial cells of hypercholesterolemic rats].

OBJECTIVE: To detect whether the activation of nuclear factor-kappa B (NF-kappaB) in endothelial cells induced by mm-LDL can promote platelet-derived growth factor-B (PDGF-B) expression in vitro, and whether it is also present in hypercholesterolemic rats in vivo, influence of age on NF-kappaB and PDGF-B signal transduction pathway. METHODS: Established hypercholesterolemic rat model by feeding with a high-cholesterol ration. The activation of NF-kappaB in aortic endothelial cells was identified by immunohistochemical staining, the expression of PDGF-B mRNA and PDGF-B protein were examined using in situ hybridization and immunohistochemistry respectively. RESULTS: In comparison with the control rats, a positive immunostaining of NF-kappaB in nuclei of aortic endothelial cells of the experimental rats was detected after a high cholesterol ration for 6 weeks. The number of endothelial cells expressing PDGF-B mRNA increased and the intensity was dependent upon the duration of high-cholesterol intake. NF-kappaB translocation (0.461 +/- 0.075 vs. 0.350 +/- 0.094, P < 0.05) and PDGF-B expression in 10-month old Wistar rats were more remarkable than that of 2-month old rats after having cholesterol for 16 weeks. Immunohistochemical staining for PDGF-B gave a similar result (0.230 +/- 0.040 vs. 0.185 +/- 0.037, P < 0.001). CONCLUSIONS: Hypercholesterolemia is capable of activating nuclear translocation of NF-kappaB and promoting expression of PDGF-B in rat aortic endothelial cells in vivo, this coincided with the results obtained in ox-LDL or mm-LDL experiments on endothelial cells in vitro. This phenomenon is much more evident in 10-month old rats which indicates that age might have a close relationship with NF-kappaB - PDGF-B signal transduction pathway.

[Molecular basis of preventive effect of human apolipoprotein-1 on murine vascular smooth muscle cell proliferation and lipid deposition induced by oxidized low density lipoprotein].

OBJECTIVE: To study the molecular basis of preventive effect of human apolipoprotein-1 (h-apoA-1) on vascular smooth muscle cell (vSMC) proliferation and lipid deposition induced by oxidized low density lipoprotein (ox-LDL). METHODS: Smooth muscle cells originated from the aortae of h-apo-A-1 transgenic mice were cultured and divided into 2 groups, one group was stimulated by ox-LDL (tester) and the other group was used as control (driver). Subtractive hybridization was used to enrich the genes differentially expressed in the vSMCs induced by ox-LDL. A subtractive library was thus established and confirmed by colony hybridization in situ and dot blot analysis. 15 clones out of the 57 differentially expressed clones were randomly chosen foe sequencing and homology analysis. The whole-length cDNA library of vSMC induced by ox-LDL was established using SMART technique. RESULTS: Three expression sequence tags (EST), all correlated with immune system, were confirmed: C1-inhibitor (C1-INH), lectin, and T cell receptor beta. The whole-length cDNA library contained 1.5 x 10(6) pfu/ml primary recombinants with insertions 0.5 - 3 kb in length. CONCLUSION: The 3 EST may be involved in the mechanism of atherogenesis by ox-LDL and the mechanism of the function of h-ApoA-1 in retarding the progression of atherogenesis induced by ox-LDL.