Biomedical subjects

Rong Lu

Publications and source records attributed to Rong Lu.

At least 37 records · Page 2Linked to original sources

PubMed2005

Experimental study of the inhibition of human hepatocarcinoma Bel7402 cells by the tripeptide tyroserleutide(YSL).

PURPOSE: To investigate the antitumor effects of tyroserleutide (tyrosyl-seryl-leucine, YSL) on human Bel7402 hepatocarcinoma in vitro and in vivo, with preliminary exploration of its antitumor mechanism. METHODS: MTT was used to observe the anticarcinogenic effects of YSL on human hepatocarcinoma Bel7402 cells in vitro. The ultrastructure of tumor cells was observed by electron microscopy. Nude mice bearing xenografts of human hepatocarcinoma Bel7402 were given daily i.p. injections of YSL or saline and an admixture of amino acids as controls, after tumor implantation. The inhibition of xenografts was determined by calculating the tumor volume and measuring tumor weight. The effects of YSL on the cell cycle and apoptosis of Bel7402 cells were determined by flow cytometry, and the effects on the ultrastructure of the cells by electron microscopy. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and proliferating-cell nuclear antigen (PCNA) immunohistochemical staining were used to investigate apoptosis in tumor tissue in nude mice. RESULTS: In vitro YSL inhibited the proliferation of human Bel7402 tumor cells and changed their ultrastructure, resulting in the necrosis and apoptosis of the tumor cells. YSL at 80, 160, or 320 microg/kg/d inhibited tumor growth in nude mice by 40.26, 64.17, and 59.19%, respectively, which are significantly lower than the inhibition exerted by saline and an admixture of YSL amino acids (P<0.05). The ultrastructure and cell cycle of human hepatocarcinoma Bel7402 cells were changed by treatment with YSL, with a rate of apoptosis higher than that of the control group. TUNEL and PCNA analysis showed that YSL inhibited the proliferation of tumor cells and induced apoptosis at the level of the cell. CONCLUSIONS: YSL significantly inhibited human hepatocarcinoma Bel7402 growth in vitro and in vivo. The growth inhibition of the tumor may involve necrosis and apoptosis of the tumor induced by YSL.

Animals↗

PubMed2005

Determination of structure and energetics for gibbs surface adsorption layers of binary liquid mixture 2. Methanol + water.

Vapor/methanol and vapor/methanol-water mixture interfaces have been among the benchmark liquid interfaces under extensive experimental and theoretical investigation. In this report, we studied the orientation, structure and energetics of the vapor/methanol-water interface with newly developed techniques in sum frequency generation vibrational spectroscopy (SFG-VS). Different from the interpretations in previous SFG-VS studies for a more disordered interface at higher bulk methanol concentrations, we found that the methanol-water mixture interface is well ordered in the whole concentration region. We are able to do so because direct polarization null angle (PNA) measurement allowed us to accurately determine the CH3 orientation at the interface and to separate the orientational and interface density contributions to the SFG-VS signal. We found that the CH3 groups at the interface pointed out almost perpendicularly from the interface. We further found that this well-ordered vapor/methanol-water mixture interface has an antiparallel structure. With the double layer adsorption model (DAM) and Langmuir isotherm, the adsorption free energies for the first and second layer are obtained as -1.7 +/- 0.1 kcal/mol and 0.5 +/- 0.4 kcal/mol, respectively. Therefore, the second layer adsorption is slightly negative, and this means that replacement of the second layer water molecule with methanol molecule is energetically unfavorable. Comparing this interface with the vapor/acetone-water mixture interface reported previously, we are able to correlate the second layer adsorption free energy with the work of self-association using the pairwise self- and mutual interaction energies between the water and solute molecules. These results provided detailed microscopic structural evidences for understanding of liquid interfaces.

Journal Article↗

PubMed2005

Tyroserleutide tripeptide affects calcium homeostasis of human hepatocarcinoma BEL-7402 cells.

This study aimed to observe the effects of tyroserleutide (tyrosyl-seryl-leucine, YSL) on the growth of human hepatocarcinoma BEL-7402 that was transplanted into nude mice, and explore its anti-tumor mechanism preliminarily. YSL, at doses of 80 microg x kg(-1) x d(-1), 160 microg x kg(-1) x d(-1) and 320 microg x kg(-1) x d(-1) significantly inhibited the growth of the human hepatocarcinoma BEL-7402 tumor in nude mice, producing inhibition of 21.66%, 41.34%, and 34.78%, respectively. Ultra structure of BEL-7402 tumor in nude mice showed that YSL could induce tumor cells apoptosis and necrosis, cell organelle mitochondria and endoplasmic reticulum damage, and calcium overload. By confocal laser scanning microscopy and flow cytometry, we found that 10 microg/mL YSL rapidly induced an increase of the concentration of cytoplasmic free calcium in BEL-7402 cells in vitro, and maintained high concentrations of cytoplasmic free calcium for 1 h. Then the calcium concentration began to decrease after 2 h, and was lower than that of the control group at 4 h and 24 h (p < 0.05). YSL also decreased the mitochondrial transmembrane potential of BEL-7402 cells in vitro, but had no effect on the calcium homeostasis or mitochondrial transmembrane potential of Chang liver hepatocytes. So affecting calcium homeostasis, then inducing apoptosis and necrosis may be a mechanism by which YSL inhibits the tumor growth in animal model.

Animals↗

PubMed2005

[Experimental study on gelatin-chondroitin sulfate-sodium hyaluronate tri-copolymer as novel scaffolds for cartilage tissue engineering].

OBJECTIVE: To fabricate a novel gelatin-chondroitin sulfate-sodium hyaluronate tri-copolymer scaffold and to confirm the feasibility of serving as a scaffold for cartilage tissue engineering. METHODS: Different scaffolds was prepared with gelatin-chondroitin sulfate-sodium hyaluronate tri-copolymer by varying the freezing temperatures (-20 degrees C, - 80 degrees C and liquid nitrogen). Pore size, porosity, inter pores and density were observed with light microscopy and scanning electron microscopy (SEM). The load-stiffness curves were compared between different scaffolds and normal cartilage. The number of MSCs attaching to different scaffolds and the function of cells were also detected with MTT colorimetric microassay. RESULTS: The pore size was 300 +/- 45, 230 +/- 30 and 45 +/- 10 microm; the porosity was 81%, 79% and 56%; the density was 9.41+/-0.25, 11.50 +/- 0. 36 and 29.50 +/- 0. 61 microg/mm3 respectively in different scaffolds fabricated at - 20 degrees C, - 80 degrees C and liquid nitrogen; the latter two scaffolds had nearly the same mechanical property with normal cartilage; the cell adhesion rates were 85.0%, 87.5% and 56.3% respectively in different scaffolds and the scaffolds can mildly promote the proliferation of MSCs. CONCLUSION: Gelatin-chondroitin sulfate-sodium hyaluronate tri-copolymer scaffold fabricated at -80 degrees C had proper pore size, porosity and mechanical property. It is a novel potential scaffold for cartilage tissue engineering.

Animals↗

PubMed2005

[Tissue distribution and excretion of bromotetrandrine in rats].

AIM: To study the tissue distribution and excretion of bromotetrandrine (W198) in rats. METHODS: The concentrations of W198 in biological samples were determined by an HPLC method with UV detection. RESULTS: After a single i.v. dose of 20 mg x kg(-1) W198 in rats, the parent drug concentrations in tissues were higher than those in blood at the same time. Parent drug was mainly distributed in lung, kidney, heart and liver, the peak levels were attained at 0.25 h and decreasing at 2 h after dosing in most tissues. After a single iv dose of 20 mg x kg(-1) W198 in rats, the excretion of the parent drug in urine, feces and bile amounted to 0. 150%, 2.1% and 0.063% of the dose, respectively. CONCLUSION: W198 was mostly distributed in lung. The parent drug excretion was less than 3% via urine, feces and bile.

Animals↗

PubMed2004

Expression of Dnmt1, demethylase, MeCP2 and methylation of tumor-related genes in human gastric cancer.

AIM: To explore the effect of DNA methyltransferase, demethylase and methyl-CpG binding protein MeCP2 on the expressions and methylation of hMSH2 and proto-oncogene in human gastric cancer. METHODS: Paired samples of primary gastric cancer and corresponding para-cancerous, non-cancerous gastric mucosae were obtained from surgically resected specimens of 28 patients. Transcription levels of Dnmt1, mbd2, MeCP2, p16(INK4A), hMSH2 and c-myc were detected by using real-time PCR or RT-PCR. Promoter methylation of p16(INK4A), c-myc and hMSH2 genes was assayed by methylation-specific PCR (MSP) and sequencing (mapping). Their relationships were analyzed by Fisher's exact test using the software SPSS. RESULTS: The average mRNA level of Dnmt1 gene from cancerous tissue was higher and that of mbd2 gene from cancerous tissue was lower than that from non-cancerous tissue, respectively. mbd2 was lower in cancerous tissue than in non-cancerous tissue in 14 (50.0%) of patients but higher in 3 cases (10.7%) of non-cancerous gastric tissue (P<0.001). c-myc expression was up-regulated in cancer tissues (P<0.05). The up-regulation of mbd2 was found in all patients with hypomethylated c-myc. The transcriptional levels of p16(INK4A) and MeCP2 genes did not display any difference between gastric cancerous and matched non-cancerous tissues. There were down-regulation and hypermethylation of hMSH2 in cancer tissues, and the hypermethylation of hMSH2 coexisted with down-regulated transcription. However, the transcription level of the above genes was not associated with biological behaviours of gastric cancers. CONCLUSION: The up-regulation of proto-oncogene may be the consequence of epigenetic control of gene expression by demethylase, and mbd2 is involved in the regulation of hMSH2 expression in human gastric cancer.

Aged↗

PubMed2004

The synthesis, distribution, and anti-hepatic cancer activity of YSL.

YSL was prepared stepwise from C terminal to N terminal with the side chain un-protective amino acids, Boc-Leu-OMe, Boc-Ser-OH, and Boc-Tyr-OH, as the starting materials in 39.5% total yield (31.2g/per batch). With the side chain un-protective Boc-(3,5-dibromo)-Tyr-OH and HCl.Ser-Leu-OMe as the starting materials (3,5-(3)H-Tyr)-Ser-Leu-OH was obtained in 29% yield. The determination of radioactive quantity in the urine and feces indicated that even after the administration for 130 h only 8.4% (5.35% in urine and 3.05% in feces) of total radioactive quantity from the metabolite of [3,5-(3)H-Tyr]-Ser-Leu-OH were monitored. The distribution study revealed the relative accumulation level of the individual tissue was arranged in the sequence of spleen>liver>kidney>lung>heart>muscle>brain. Selecting hepatic cancer as the target YSL significantly increased the survival time of H22 tumor cells implanted mice.

Animals↗

PubMed2004

Histone acetylation regulates p21WAF1 expression in human colon cancer cell lines.

AIM: To investigate the effect of histone acetylation on regulation of p21WAF1 gene expression in human colon cancer cell lines. METHODS: Two cell lines, Colo-320 and SW1116 were treated with either trichostatin or sodium butyrate. Expressions of p21WAF1 mRNA and protein were detected by real-time RT-PCR and Western blotting, respectively. Acetylation of two regions of p21WAF1 gene-associated histones and total cellular histones were examined by chromatin immunoprecipitation assay and Western blotting. RESULTS: Trichostatin or sodium butyrate re-activated p21WAF1 transcription resulted in up-regulated p21WAF1 protein level in colon cancer cell lines. Those effects were accompanied by an accumulation of acetylated histones in total cellular chromatin and p21WAF1 gene-associated region of chromatin. CONCLUSION: Histone acetylation regulates p21WAF1 expression in human colon cancer cell lines, Colo-320 and SW1116.

Acetylation↗

PubMed2004

Functional and molecular evidence of MaxiK channel beta1 subunit decrease with coronary artery ageing in the rat.

Large-conductance, voltage- and Ca2+ -activated K+ channels (MaxiK, BK) are key regulators of vascular tone. Vascular MaxiK are formed by the pore-forming alpha subunit and the modulatory beta1 subunit, which imprints unique kinetics, Ca2+/voltage sensitivities and pharmacology to the channel. As age progresses, alpha subunit functional expression and protein levels diminish in coronary myocytes. However, whether ageing modifies beta1 subunit expression or the mechanism of alpha subunit reduction is unknown. Thus, we examined functional and pharmacological characteristics of MaxiK, as well as alpha and beta1 transcript levels in coronary myocytes from young and old F344 rats. The mechanism of age-dependent alpha subunit protein reduction involves its transcript downregulation. A corresponding loss of beta1 transcripts was also detected in old myocytes, suggesting a proportional age-dependent decrease of beta1 to alpha subunit protein. Indeed, MaxiK channel properties, defined by coassembly of beta1 and alpha subunits, were equivalent in young versus old, for example in terms of (i) activation kinetics, (ii) sensitivity to Ca2+ levels > 1 microm (iii) dehydrosoyasaponin-I-induced activation, and (iv) iberiotoxin blockade. Consistent with less MaxiK expression/function in older myocytes, the ability of iberiotoxin to contract coronary rings was reduced approximately 50% with ageing confirming our previous findings. 5-Hydroxytryptamine (5-HT) contractile efficacy was reduced by iberiotoxin pretreatment in young > old coronary arteries (explained by larger iberiotoxin-induced contraction and decreased dynamic range for 5-HT contraction in young versus old) with no apparent differences in nitroglycerine-induced relaxation. We propose that the age-related MaxiK reduction involves a parallel decrease of alpha and beta1 functional expression via a transcript downregulatory mechanism; a major impact on basal and possibly stimulated coronary contraction may contribute to altered coronary flow regulation and coronary morbidity in the elderly.

Aging↗

PubMed2004

[Effect of eukaryotic expression plasmid DNA methyltransferase gene on methylation status and transcription level of DNA mismatch repair genes in human colon cancer cell line].

OBJECTIVE: To analyze the effect of eukaryotic plasmids containing sense or antisense DNA methyltransferase (Dnmt1) genes on the methylation status and transcription level of DNA mismatch repair (MMR) genes and microsatellite instability (MSI) in human colon cancer cell line. METHODS: Human colorectal cells of the SW1116 line were cultured. Recombinant plasmids containing sense Dnmt1 (HMT) or antisense Dnmt1 (THM) gene, pCMV-HMT and pCMV-THM, were constructed. Then pCMV-HMT, pCMV-THM, and pcMV blank plasmid were transfected into SW1116 cells respectively by using lipofectAMINE. The expression of Dnmt1 protein was examined by Western blotting. The transcription levels of hMLH1 and hMSH2 genes were detected by using real-time (RT-PCR). The status of methylation in promoters of hMLH1 and hMSH2 genes were examined with methylation specific PCR (MSP). The MSI of DNA in SW1116 cells was evaluated by silver-stained polyacrylamide gel electrophoresis. RESULTS: Both the expressions of the hMLH1 and hMSH2 gene mRNAs were remarkably decreased in the SW1116-HMT cells in comparison with those in the untransfected cells. The expression of hMSH2 gene mRNA in the SW1116-THM cells was remarkably increased in comparison with that in the untransfected cells. No significant difference in the expressions of the hMLH1 and hMSH2 gene mRNAs was found between the SW1116 cells transfected with blank pCMV and the untransfected SW1116 cells. MSP showed that the methylation level in the regions of hMLH1 and hMSH2 promoters was remarkably increased in the SW1116 cells transfected with sense Dnmtl plasmid. However, in the SW1116 cells the hMSH2 promoter region was changed from partially-methylated into de-methylated, and the hMLH1 promoter region remained non-methylated. MST test showed that extra bands indicating MSI were seen only in the D2S123 groups. CONCLUSION: Dnmt1 regulates the expression and methylation status of MMR genes and affects MSI in human colon cancer cell line SW1116.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Ouabain increases myofibrillar Ca2+ sensitivity but does not influence the Ca2+ release in human skinned fibres.

The present study investigated the impact of the Na(+) pump inhibitor ouabain (g-strophanthin) on Ca(2+) sensitivity and Ca(2+) release in human right auricular trabeculae (coronary bypass) and in skinned muscle fibres from left ventricular myocardium (cardiac transplantation, dilated cardiomyopathy). A time-dependent increase in force of contraction was observed in right auricular trabeculae in response to ouabain (100 nM) before the intracellular Ca(2+) transient (fura-2) increased (n=6). In triton X-skinned fibres (no sarcoplasmic reticulum) of human failing myocardium, ouabain (1-100 nM) concentration-dependently increased tension at a free extracellular Ca(2+) concentration of 1 microM and the Hill coefficient of the Ca(2+)-dependent tension development. Ouabain (1-100 nM) did not directly induce a Ca(2+) release out of the sarcoplasmic reticulum, nor did it alter the caffeine (10 mM) induced sarcoplasmic reticulum Ca(2+) release in saponin-skinned fibre preparations in which the sarcoplasmic reticulum had been Ca(2+)-loaded. In conclusion, ouabain increases myofibrillar Ca(2+) sensitivity possibly due to an increase in the cooperativity of the thick and thin myofilaments. This mechanism may additionally contribute to the positive inotropic effect of ouabain.

Adult↗

PubMed2004

[Study on the inhibitory effect of small tripeptide CMS024 on tumor growth and metastasis in nude mice model of human hepatocellular carcinoma metastasis].

OBJECTIVE: This experiment was designed to study the effect of small molecule tripeptide CMS024 on tumor growth and metastasis in a nude mice model of human hepatocellular carcinoma (HCC) metastasis. METHODS: Highly metastatic human HCC cell strain HCCLM6 was injected into subcutaneous region of nude mice. When the subcutaneous tumor reached 0.8 cm in diameter, the tumor was removed and cut into small pieces about 1 mm in diameter and implanted orthotopically into the liver of 20 BALB/c nude mice, which were randomized into treatment group and control group each with 10 mice. The treatment group received daily CMS024 intraperitoneal injection at the dose of 300 microg/kg beginning from the second postoperative day. The control group received intraperitoneal injection of equal amount of 0.85% sodium chloride solution. The mice were observed for signs of disease development. Thirty-five days later, the mice were sacrificed and abdominal and pulmonary metastases were recorded and peripheral blood hematological and biochemical parameters were determined. RESULTS: After 35 days of intervention, all the 10 mice in the treatment group were alive and well, but there were only 9 living mice in the control group. The mean tumor weights were 1.9 g +/- 0.5 g in the treatment group and 2.3 g +/- 0.8 g in the control group (P > 0.05). The abdominal wall metastases and intraperitoneal metastases were 100% for the control group and only 60% and 50%, respectively, for the treatment group (P < 0.05). Bloody ascites and gross intrahepatic metastatic nodules were found in 70% and 90% of nude mice, respectively, for the control group, and 20% and 40%, respectively, for the treatment group (P > 0.05). The median number of grades I, II, III and IV pulmonary metastases were 92, 24, 15 and 16, respectively, for the control group, and 24, 20, 10 and 8, respectively, for the treatment group. There were statistically significant differences in the number of grade I pulmonary metastases between the treatment group and the control group (24 vs 92, P < 0.05). No statistically significant differences in the body weight, peripheral blood hematological and biochemical parameters were observed between the two groups. No toxic effects were observed during the observation period. CONCLUSIONS: Small molecule tripeptide CMS024 demonstrated positive effects to retard tumor growth and inhibit loco-regional and long distance metastases in a nude mice model of human HCC metastasis, and no obvious toxic or side effects on the tumor bearing nude mice.

Animals↗

PubMed2004

Epigenetic modification regulates both expression of tumor-associated genes and cell cycle progressing in human colon cancer cell lines: Colo-320 and SW1116.

The aim of this study is to assess the effects of DNA methylation and histone acetylation, alone or in combination, on the expression of several tumor-associated genes and cell cycle progression in two established human colon cancer cell lines: Colo-320 and SW1116. Treatments with 5-aza-2-deoxycytidine (5-aza-dC) and trichostatin A, alone or in combination, were applied respectively. The methylation status of the CDKN2A promoter was determined by methylation-specific PCR, and the acetylated status of the histones associated with the p21WAF1 and CDKN2A genes was examined by chromatin immunoprecipitation. The expression of the CDKN2A, p21WAF1, p53, p73, APC, c-myc, c-Ki-ras and survivin genes was detected by real-time RT-PCR and RT-PCR. The cell cycle profile was established by flow cytometry. We found that along with the demethylation of the CDKN2A gene promoter in both cell lines induced by 5-aza-dC alone or in combination with TSA, the expression of both CDKN2A and APC genes increased. The treatment of TSA or sodium butyrate up-regulated the transcription of p21WAF1 significantly by inducing the acetylation of histones H4 and H3, but failed to alter the acetylation level of CDKN2A-associated histones. No changes in transcription of p53, p73, c-myc, c-Ki-ras and survivin genes were observed. In addition, TSA or sodium butyrate was shown to arrest cells at the G1 phase. However, 5-aza-dC was not able to affect the cell cycle progression. In conclusion, regulation by epigenetic modification of the transcription of tumor-associated genes and the cell cycle progression in both human colon cancer cell lines Colo-320 and SW1116 is gene-specific.

Acetylation↗

PubMed2004

5-Aza-2'-deoxycitydine induces demethylation and up-regulates transcription of p16INK4A gene in human gastric cancer cell lines.

BACKGROUND: To investigate the effects of DNA methylation on the expression of tumor-associated genes and the cell cycle in human gastric cancer cells. METHODS: Two gastric cancer cell lines (MKN-45 and HGC-27) were treated with DNA methyltransferase (DNMT) inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC). The expressions of p16INK4A, p21WAF1, p53, p73, c-Ha-ras and c-myc genes mRNA were detected by using reverse transcription PCR (RT-PCR). DNA methylation status of p16INK4A gene promoter was assayed by bisulfite modification and sequencing. The cell cycle was analyzed by using flow cytometry (FCM). RESULTS: 5-aza-dC induced the demethylation of p16INK4A gene promoter. The expression of p16INK4A mRNA was obviously up-regulated by treatment with 10 micro mol/L (MKN-45 cells) or 5 micro mol/L (HGC-27 cells) of 5-aza-dC for 24 hours. However, 5-aza-dC treatment failed to regulate the expressions of p21WAF1, p53, p73, c-Ha-ras and c-myc genes in MKN-45 and HGC-27 cells. Furthermore, 5-aza-dC induced the cell cycle arrest in G1 phase in HGC-27 cell, but not in MKN-45 cell. CONCLUSIONS: DNA methylation regulates the transcription of p16INK4A but not p21WAF1 and proto-oncogenes in human gastric cancer cell lines MKN-45 and HGC-27.

Azacitidine↗

PubMed2004

[Pharmacokinetics of bromotetrandrin (W198) in rats and beagle dogs].

AIM: To study the pharmacokinetics of bromotetrandrine (W198) in rats and beagle dogs. METHODS: The concentrations of W198 in serum were determined using HPLC method with UV detection. RESULTS: The pharmacokinetic parameters of W198 after single iv doses of W198 10, 20 and 40 mg x kg(-1) in rats were as follows: T1/2beta were 6.60, 7.36 and 6.77 h, AUC0-24 h were 3.797, 7.371 and 15.192 mg x h x L(-1), Vd were 7.14, 4.33 and 4.13 L x kg(-1), CL were 2.83, 2.60 and 2.71 L x (kg x h)(-1), respectively. The T1/2beta and AUCo-24 h of W198 after single im dose of W198 20 mg x kg(-1) in rats were 11.61 h and 12.646 mg x h x L(-1). The im bioavailability of W198 in rats was 56.9%. The T1/2beta, AUC0-24 h, Vd and CL of W198 after single iv dose of W198 5 mg x kg(-1) in beagle dogs were 11.72 h, 12.646 mg x h x L(-1), 0.70 L x kg(-1) and 0.46 L x (kg x h)(-1), respectively. The plasma protein binding ratio of W198 with human serum protein was 78.0%. CONCLUSION: The absorption of W198 in rats was of first order kinetics.

Alkaloids↗

PubMed2004

Effect of type I collagen on the adhesion, proliferation, and osteoblastic gene expression of bone marrow-derived mesenchymal stem cells.

OBJECTIVE: To investigate the effects of porous poly lactide-co-glycolide (PLGA) modified by type I collagen on the adhesion, proliferation, and differentiation of rabbit marrow-derived mesenchymal stem cells (MSCs). METHODS: The third generation MSCs isolated from mature rabbits by density gradient centrifugation were cultured at different initial concentrations on 0.3 cm x 1.2 cm x 2.0 cm 3-D porous PLGA coated by type I collagen in RPMI 1640 containing 10% fetal calf serum, while cultured on PLGA without type I collagen as control. The cells adhesive and proliferative behavior at 7, 14, and 21 days after inoculation was assessed by determining the incorporation rate of [(3)H]-TdR. In order to examine MSCs differentiation, the expression of osteoblasts marker genes, osteocalcin (OCN), alkaline phosphatase (ALP), osteopontin (OPN) mRNA, were evaluated by reverse transcription-polymerase chain reaction (RT-PCR), and further more, the cell morphology at 21 days was also observed by scanning electron microscope (SEM). RESULTS: Type I collagen promoted cell adhesion on PLGA. The valve was significantly higher than controls (6 h, 2144 cpm+/-141 cpm vs. 1797 cpm+/-118 cpm, P=0.017; 8 h, 2311 cpm+/-113 cpm vs. 1891 cpm+/-103 cpm, P=0.01). The cells which cultured on PLGA coated with type I collagen showed significantly higher cell proliferation than controls on the 7 th day (1021 cpm+/-159 cpm vs. 451 cpm+/-67 cpm, P=0.002), the 14th day (1472 cpm+/-82 cpm vs. 583 cpm+/-67 cpm, P<0.001) and 21 th day (1728 cpm+/-78 cpm vs. 632 cpm+/-55 cpm, P<0.001). Osteoblasts markers, OCN, ALP, OPN mRNA, were all detected on PLGA coated by type I collagen on the 21 th day, but OCN, OPN mRNA could not be found in controls. Spindle and polygonal cells well distributed on the polymer coated by type I collagen while cylindric or round cells in controls. CONCLUSIONS: Type I collagen is effective in promoting the adhesion, proliferation and differentiation of MSCs on PLGA.

Biocompatible Materials↗

PubMed2003

[Effects of collagen I coating on the porous poly-lactide-co-glycolid on adhesion, proliferation, and differentiation of mesenchymal stem cells].

OBJECTIVE: To investigate the effects of collagen I on the adhesion, proliferation, and differentiation of MSCs on PLGA. METHODS: Collagen I was added onto the surface of pores in pieces of 3-D porous poly-lactide-co-glycolid (PLGA). Bone marrow-derived mesenchymal stem cells (MSCs) were obtained from New Zealand rabbits and were cultured for 3 generations, inoculated into the pores of PLGA pieces with the volume of 0.3 cm x 1.2 cm x 2.0 cm, and then cultured in solution with [(3)H]-thymidine deoxyribose (TdR). PLGA pieces not coated by collagen I were used as controls. The incorporation rate of [(3)H]-TdR was detected 2, 4, 6, and 8 hours, and 7, 14, and 21 days after culture, shown in count per minute (CPM) value, to determine the adhesion and proliferation of the MSCs. RT-POCR was used to examine the expressions of mRNA of the osteoblast markers: osteocalcin (OCN), alkaline phosphatase (ALP), and osteopontin (OPN). Scanning electron microscopy (SEM) was used to observe the morphology of MSCs. RESULTS: The CPM value since 6 hours after culture between the experimental group and control group began to be significantly different (both P < 0.05) The CPM values 7, 14, and 21 days after culture between the experimental group and control groups (P < 0.05 or P < 0.01). OCN, ALP, and OPN mRNA were expressed in MSCs of the experimental group and only ALP mRNA was weakly expressed in the control group. SEM showed the distribution of spindle and polygonal cells in the pores of the 3-D PLGA pieces and distribution of cylindrical or round cells in the control group. CONCLUSION: Collagen I is effective in promoting the adhesion, proliferation, and differentiation of MSCs on PLGA.

Animals↗

PubMed2003

The protective effects of monophosphoryl lipid A on the ischemic myocardium and endothelium in rats.

Previous investigations have shown that a single dose of low-density lipoprotein (LDL) injection causes a marked decrease in endothelium-dependent relaxation, and that endothelial dysfunction aggravates myocardial injury due to ischemia-reperfusion in atherosclerotic animals. Monophosphoryl lipid A-induced delayed preconditioning preserves the ischemic myocardium and endothelial cells. The objective of the present study was to examine the effect of monophosphoryl lipid A on endothelial function and ischemia-reperfusion-induced myocardial injury in the rats treated with LDL. A single injection of native LDL (4 mg/kg, i.v.) caused a significant decrease in vasodilator responses to acetylcholine and an increase in the serum level of asymmetric dimethylarginine, the endogenous nitric oxide synthase inhibitor. Pretreatment with monophosphoryl lipid A (300 or 450 microg/kg, i.p.) significantly improved endothelium-dependent relaxation and decreased concentrations of asymmetric dimethylarginine, and the effects of monophosphoryl lipid A were attenuated by L-nitro-arginine-methylester, but not by aminoguanidine. LDL treatment only aggravated the decreased coronary flows but did not affect cardiac dysfunction due to ischemia-reperfusion in the rats treated with LDL. Pretreatment with monophosphoryl lipid A significantly improved cardiac dysfunction by ischemia-reperfusion in the rats treated with or without LDL, an effect that was abolished by aminoguanidine. The present study suggests that: (1) a single injection of native LDL causes a decrease in endothelium-dependent relaxation, and aggravates the decrease of coronary flow due to ischemia-reperfusion, (2) pretreatment with monophosphoryl lipid A protects the myocardium against ischemia-reperfusion in the rats treated with or without native LDL, and (3) the protective effect of monophosphoryl lipid A on endothelial cells is related to reduction of asymmetric dimethylarginine level.

Animals↗