Effects of hydroxyapatite nanoparticles on proliferation and apoptosis of human hepatoma BEL-7402 cells

The use of size-defined DNA-functionalized calcium phosphate nanoparticles to minimise intracellular calcium disturbance during transfection

Calcium phosphate-based transfection methods are frequently used to transfer DNA into living cells. However, it has so far not been studied in detail to what extend the different transfection methods lead to a net calcium uptake. Upon subsequent resolution of the calcium phosphate, intracellular free ionic calcium-surges could result, inducing as side effect various physiological responses that may finally result in cell death. Here we investigated the overall calcium uptake by the human bladder carcinoma cell line T24 during the standard calcium phosphate transfection method and also during transfection with custom-made calcium phosphate/DNA nanoparticles by isotope labelling with (45)calcium. (45)Calcium uptake was strongly increased after 7h of standard calcium phosphate transfection but not if the transfection was performed with calcium phosphate nanoparticles. Time lapse imaging microscopy using the calcium-sensitive dye Fura-2 revealed large transient increases of the intracellular free calcium level during the standard calcium phosphate transfection but not if calcium phosphate nanoparticles were used. Consistently, the viability of cells transfected by calcium phosphate/DNA nanoparticles was not changed, in remarkable contrast to the standard method where considerable cell death occurred.

Hydroxyapatite nano and microparticles: correlation of particle properties with cytotoxicity and biostability

Synthetic colloid and gel hydroxyapatite (HA) nanoparticles (NPs) were spray dried to form microparticles (MPs). These are intended for use as slow release vaccine vectors. The physico-chemical properties of gel and colloid NPs and MPs were compared to those of HA obtained commercially. Their cytotoxicity to human monocytes'-derived macrophages (HMMs) was assessed in vitro using a range of techniques. These included the MTT assay, LDH leakage and a confocal based live-dead cell assay. Cytotoxicity differed significantly between preparations, with the suspended gel preparation being the most toxic (31-500 microg/ml). Other preparations were also toxic but only at higher concentrations (>250 microg/ml). Transmission electron microscopy (TEM) and stereology showed variable cellular uptake and subsequent dissolution of the various forms of HA. We have demonstrated that HA particle toxicity varied considerably and that it was related to their physico-chemical properties. Cell death correlated strongly with particle load. The intracellular dissolution of particles as a function of time in HMM suggests that increased cytoplasmic calcium load is likely to be the cause of cell death. Some HA NPs eluded the phagocytic pathway and a few were even seen to enter the nuclei through nuclear pores.

p53 reaction to apoptosis induced by hydroxyapatite nanoparticles in rat macrophages

The effects and mechanism of hydroxyapatite (HAP) nanoparticles (NPs) on the induction of cytotoxicity and apoptosis in rat macrophages was evaluated by testing the antiproliferative effect of HAP NPs with agar overlay and direct contact methods. The apoptotic phenotype of the macrophages was observed by transmission electron microscopy (TEM), and the variation of transcription and expression of a cell apoptosis related gene (p53) was determined by semiquantitative RT-PCR and western blotting. The results showed that a dose-dependent proliferative inhibition of macrophages was induced by HAP NPs (30-80 nm) at concentrations between 20 and 200 microg/mL. The characteristic morphological changes of apoptosis were observed in macrophages after treatment with HAP NPs for 24 h. Furthermore, p53 mRNA levels significantly increased when macrophages were incubated with 200 microg/mL HAP NPs (p < 0.01). Western blot analysis showed that 100 microg/mL HAP NPs upregulated p53. The conclusion is that HAP NPs can induce p53 expression through phosphorylation, which promotes downstream genes and finally results in cell apoptosis. Moreover, p53 may be one of the ideal indictors to evaluate the biological safety of ceramic nanoparticles.

Influence of spray-dried hydroxyapatite-5-fluorouracil granules on cell lines derived from tissues of mesenchymal origin

In our previous work we described the preparation and characterization of spray dried hydroxyapatite micro granules loaded with 5-fluorouracil (5-FU). These loaded particles are used as a model drug delivery system (DDS). In this study we examined the in vitro response of two cell lines derived from different tissues to 5-FU loaded granules (LG). Both cell lines, either L929 cells of a mouse fibroblast lineage or cells originating from a rat osteosarcoma (ROS 17/2.8) showed a dose dependent decrease in cell proliferation in response to 5-FU-, either dissolved in the culture medium or loaded onto particles. The response of the two cell lines to loaded and nonloaded particles was different. The effect of LG and of a corresponding concentration of free 5-FU was practically the same for the ROS 17/2.8 cells indicating that ROS 17/2.8 cells were not affected by the carrier material. In contrast, L929 cells showed a slight decrease in cell proliferation also in the presence of granules not loaded with 5-FU. This is thought to be attributed to the inhibition of mitogenesis by phosphocitrates, already demonstrated in fibroblasts. In summary, we found that the loaded 5-FU kept its effectivity after the spray drying process and that the response towards the granules varied with cell type. This is the first step towards a tissue specific DDS.

Kinetic analysis of superoxide anion radical-scavenging and hydroxyl radical-scavenging activities of platinum nanoparticles

There are few reports on the physiological effects of metal nanoparticles (nps), especially with respect to their functions as scavengers for superoxide anion radical (O2(.-)) and hydroxyl radical (.OH). We tried to detect the scavenging activity of Pt nps using a hypoxanthine-xanthine oxidase system for O2(.-) and using a Fenton and a UV/H2O2 system for .OH. Electron spin resonance analysis revealed that 2 nm particle size Pt nps have the ability to scavenge O2(.-) and .OH. The calculated rate constant for the O2(.-)-scavenging reaction was 5.03 +/- 0.03 x 10(7) M (-1) s (-1). However, the analysis of the Fenton and UV/H 2O 2 system in the presence of Pt nps suggested that the .OH-scavenging reaction cannot be determined in both systems. Among particle sizes tested from 1 to 5 nm, 1 nm Pt nps showed the highest O2(.-)-scavenging ability. Almost no cytotoxicity was observed even after adherent cells (TIG-1, HeLa, HepG2, WI-38, and MRC-5) were exposed to Pt nps at concentrations as high as 50 mg/L. Pt nps scavenged intrinsically generated reactive oxygen species (ROS) in HeLa cells. Additionally, Pt nps significantly reduced the levels of intracellular O2(.-) generated by UVA irradiation and subsequently protected HeLa cells from ROS damage-induced cell death. These findings suggest that Pt nps may be a new type of antioxidant capable of circumventing the paradoxical effects of conventional antioxidants.

Inorganic nanoparticles as carriers of nucleic acids into cells

The transfer of nucleic acids (DNA or RNA) into living cells, that is, transfection, is a major technique in current biochemistry and molecular biology. This process permits the selective introduction of genetic material for protein synthesis as well as the selective inhibition of protein synthesis (antisense or gene silencing). As nucleic acids alone are not able to penetrate the cell wall, efficient carriers are needed. Besides viral, polymeric, and liposomal agents, inorganic nanoparticles are especially suitable for this purpose because they can be prepared and surface-functionalized in many different ways. Herein, the current state of the art is discussed from a chemical viewpoint. Advantages and disadvantages of the available methods are compared.

Effect of hydroxyapatite nanoparticles on the growth and p53/c-Myc protein expression of implanted hepatic VX2 tumor in rabbits by intravenous injection

AIM: To evaluate the effect of hydroxyapatite nano-particles (Nano HAP) by intravenous injection on the inhibition of implanted hepatic VX₂ tumor growth in rabbits and cell p53/c-Myc protein expression.

METHODS: 60 hepatic VX₂ tumor-bearing rabbits was randomly divided into five groups. Nano HAP collosol 20 mg/kg, 40 mg/kg, 5-FU solutions 20 mg/mL, mixed liquor of 5-FU solution 20 mg/mL and Nano HAP collosol 20 mg/kg were infused by vein, normal saline conducted as the control. The general state, weight, liver function and gross tumor volume were detected dynamically. The expression of p53 and c-Myc gene protein in tumor tissue was detected by immunohistochemistry methods.

RESULTS: The growth of implanted hepatic VX₂ tumors was significantly inhibited in all therapy groups, 3 wk after the injection, the tumor control rates in Nano HAP collosol groups were 25.5% and 32.5% respectively, and the gross tumor volumes were obviously less than that of control group. (24.81 ± 5.17 and 22.73 ± 4.23 vs 33.32 ± 5.26, P < 0.05). The tumor control rate of 5-FU group was 43.7% (18.74 ± 4.40 vs 33.32 ± 5.26, P < 0.05), but the general state of the animals after injection aggravated; and the adverse reaction in the drug combination group obviously decreased. Due to the effect of Nano HAP, the positive expression of tumor associated the mutated p53 and c-Myc in tumor tissue was decreased obviously compared with the control group.

CONCLUSION: Nano HAP has evident inhibitory action on rabbit implanted hepatic VX₂ tumor in vivo, which may be the result of decreasing the expression of the mutated p53 and c-myc, and drug combination can obviously decrease the adverse reaction of 5-FU.

Mitochondria-dependent apoptosis induced by nanoscale hydroxyapatite in human gastric cancer SGC-7901 cells

Nanoscale hydroxyapatite (nano-HAP) has been reported to exhibit anti-cancer effect on several human cancers, but the molecular mechanism of which remains unclear. The aim of this study was to explore the mechanisms by investigating the effects of nano-HAP on human gastric cancer SGC-7901 cells. Our results showed that nano-HAP significantly reduced cell viability, and induced apoptosis in SGC-7901 cells characterized by hypodiploid DNA contents, morphological changes and DNA fragmentation. The increase in apoptosis was accompanied with the increased expression of Bax, a pro-apoptotic protein, and decreased expression of Bcl-2, an anti-apoptotic protein, the decrease of mitochondrial membrane potential and the release of cytochrome c from mitochondria into cytosol. Furthermore, the activation of caspases-3, and -9, but not activation of caspases-8 was induced by nano-HAP. Z-VAD-fmk, a universal caspase inhibitor, dose-dependently inhibited nano-HAP-induced apoptosis. This study demonstrates that nano-HAP inhibits the proliferation of SGC-7901 cells by inducing apoptosis, and the apoptotic pathway of nano-HAP-induced apoptosis is mediated through the mitochondrial-dependent and caspase-dependent pathway.

Inhibitory effect of antisense oligonucleotide on the expression of survivin gene and proliferation of human hepatocellular carcinoma cell line SMMC-7721

AIM: To investigate the inhibitory effect of survivin antisense oligonucleotide (ASODN) on the expression of survivin gene and proliferation of human hepatocellular carcinoma cell line SMMC-7721.

METHODS: The 20mer antisense oligonucleotide (ASODN) targeted to the promotor region of survivin mRNA was designed and synthesized. The expression of survivin gene in hepatocellular carcinoma cell line SMMC-7721 was blocked by means of ASODN transfection mediated by DOTAP liposomal reagent. The changes of survivin protein and mRNA expression after transfection were assessd by Western blot and in situ hybridization, respectively. The apoptotic rate was detected by flow cytometer. The changes of cell adherent rate, cell growth activity, and the inhibitory rate of cell growth were also studied.

RESULTS: The expression of survivin protein and mRNA was decreased markedly after survivin ASODN transfection (69.59 vs 10.71, and 75.61 vs 22.94, P < 0.01). Meanwhile, the cell adherent rate also decreased markedly (90.68% vs 33.16%, P < 0.01) while the apoptotic rate increased markedly (0.7% vs 31.35%, P < 0.01). The inhibitory effect on the cell growth could maintain about a week after transfection, and the highest inhibitory rate could be 71.8% three d after transfection.

CONCLUSION: Transfection of ASODN targeted to the promotor region of survivin mRNA by DOTAP liposomal transfection reagent can down-regulate the expression of survivin protein and mRNA significantly in 7721 cell line and inhibit the proliferation of cancer cells. survivin may be an important target in the therapy of hepatocellular carcinoma.