GT1b functions as a novel endogenous agonist of toll-like receptor 2 inducing neuropathic pain.

Spinal cord microglia contribute to nerve injury-induced neuropathic pain. We have previously demonstrated that toll-like receptor 2 (TLR2) signaling is critical for nerve injury-induced activation of spinal cord microglia, but the responsible endogenous TLR2 agonist has not been identified. Here, we show that nerve injury-induced upregulation of sialyltransferase St3gal2 in sensory neurons leads to an increase in expression of the sialylated glycosphingolipid, GT1b. GT1b ganglioside is axonally transported to the spinal cord dorsal horn and contributes to characteristics of neuropathic pain such as mechanical and thermal hypersensitivity. Spinal cord GT1b functions as an TLR2 agonist and induces proinflammatory microglia activation and central sensitization. Pharmacological inhibition of GT1b synthesis attenuates nerve injury-induced spinal cord microglia activation and pain hypersensitivity. Thus, the St3gal2-GT1b-TLR2 axis may offer a novel therapeutic target for the treatment of neuropathic pain.

Polyamidoamine dendrimer-conjugated triamcinolone acetonide attenuates nerve injury-induced spinal cord microglia activation and mechanical allodynia.

Background Accumulating evidence on the causal role of spinal cord microglia activation in the development of neuropathic pain after peripheral nerve injury suggests that microglial activation inhibitors might be useful analgesics for neuropathic pain. Studies also have shown that polyamidoamine dendrimer may function as a drug delivery vehicle to microglia in the central nervous system. In this regard, we developed polyamidoamine dendrimer-conjugated triamcinolone acetonide, a previously identified microglial activation inhibitor, and tested its analgesic efficacy in a mouse peripheral nerve injury model. Result Polyamidoamine dendrimer was delivered selectively to spinal cord microglia upon intrathecal administration. Dendrimer-conjugated triamcinolone acetonide inhibited lipoteichoic acid-induced proinflammatory gene expression in primary glial cells. In addition, dendrimer-conjugated triamcinolone acetonide administration (intrathecal) inhibited peripheral nerve injury-induced spinal cord microglial activation and the expression of pain-related genes in the spinal cord, including Nox2, IL-1ß, TNF-α, and IL-6. Dendrimer-conjugated triamcinolone acetonide administration right after nerve injury almost completely reversed peripheral nerve injury-induced mechanical allodynia for up to three days. Meanwhile, dendrimer-conjugated triamcinolone acetonide administration 1.5 days post injury significantly attenuated mechanical allodynia. Conclusion Our data demonstrate that dendrimer-conjugated triamcinolone acetonide inhibits spinal cord microglia activation and attenuates neuropathic pain after peripheral nerve injury, which has therapeutic implications for the treatment of neuropathic pain.

Dipeptide-functionalized polyamidoamine dendrimer-mediated apoptin gene delivery facilitates apoptosis of human primary glioma cells.

Glioblastoma multiform (GBM) is the most frequent and aggressive form of brain tumors in adults. However, the development of more efficient and safe nonviral vector gene therapy represents a promising therapeutic approach, using a tumor-specific killer gene, named apoptin. In this study, we describe the efficacy of non-viral gene delivery vectors, the amino acid-conjugated PAMAM derivatives (PAMAM-H-R and PAMAM-H-K) in delivering a therapeutic gene, displaying affinity toward human primary glioma cells (GBL-14 cells) and dermal fibroblasts. We analyzed transfection efficiency, using luciferase (Luci) and a pDNA encoding for enhanced fluorescent protein (EGFP), and cytotoxicity in both cells. The results show that transfection efficiency of PAMAM-H-R improved compared to native PAMAM dendrimer, but cytotoxicity of PAMAM-H-R and PAMAM-H-K were very low. We treated both cells with a polyplex formation of PAMAM-H-R or PAMAM-H-K/apoptin, and analyzed their cellular uptake and localization by flow cytometry and confocal microscopy. Furthermore, we analyzed the endosomal escape effect using TEM images, and found that PAMAM-H-R showed very fast escape from endosome to the cytosol. Caspase 3 activity assay, cell cycle distribution, and JC-1 analysis showed apoptosis induced by apoptin in GBL-14 cells. This indicates that PAMAM-H-R can be a potential nonviral vector gene delivery carrier for brain tumor therapy. The present study demonstrates that PAMAM-H-R/apoptin gene polyplex can be used as an effective therapeutic candidate for GBM due to its selective induction of apoptosis in primary glioma cells as a potential nonviral gene delivery carrier for brain tumor therapy.

Protective effect of recombinant soluble neprilysin against ß-amyloid induced neurotoxicity.

A few decades ago, researchers found emerging evidence showing that a number of sequential events lead to the pathological cascade of Alzheimer's disease (AD) which is caused by the accumulation of amyloid beta (Aß), a physiological peptide, in the brain. Therefore, regulation of Aß represents a crucial treatment approach for AD. Neprilysin (NEP), a membrane metallo-endopeptidase, is a rate-limiting peptidase which is known to degrade the amyloid beta peptide. This study investigated soluble NEP (sNEP) produced by recombinant mammalian cells stably transfected with a non-viral NEP expression vector to demonstrate its protective effect against Aß peptides in neuronal cells in vitro. Stably transfected HEK 293 cells were used to purify the soluble protein. sNEP and Aß peptide co-treated hippocampal cells had a decreased level of Aß peptides shown by an increase in cell viability and decrease in apoptosis measured by the CCK-8 and relative caspase-3 activity ratio assays, respectively. This study shows that stably transfected mammalian cells can produce soluble NEP proteins which could be used to protect against Aß accumulation in AD and subsequently neuronal toxicity. Additionally, approaches using protein therapy for potential targets could change the pathological cascade of Alzheimer's disease.

Protective Effect of Tat PTD-Hsp27 Fusion Protein on Tau Hyperphosphorylation Induced by Okadaic Acid in the Human Neuroblastoma Cell Line SH-SY5Y.

Alzheimer's disease (AD) is an age-related disorder that causes a loss of brain function. Hyperphosphorylation of tau and the subsequent formation of intracellular neurofibrillary tangles (NFTs) are implicated in the pathogenesis of AD. Hyperphosphorylated tau accumulates into insoluble paired helical filaments that aggregate into NFTs; therefore, regulation of tau phosphorylation represents an important treatment approach for AD. Heat shock protein 27 (Hsp27) plays a specific role in human neurodegenerative diseases; however, few studies have examined its therapeutic effect. In this study, we induced tau hyperphosphorylation using okadaic acid, which is a protein phosphatase inhibitor, and generated a fusion protein of Hsp27 and the protein transduction domain of the HIV Tat protein (Tat-Hsp27) to enhance the delivery of Hsp27. We treated Tat-Hsp27 to SH-SY5Y neuroblastoma cells for 2 h; the transduction level was proportional to the Tat-hsp27 concentration. Additionally, Tat-Hsp27 reduced the level of hyperphosphorylated tau and protected cells from apoptotic cell death caused by abnormal tau aggregates. These results reveal that Hsp27 represents a valuable protein therapeutic for AD.

Paclitaxel coating on the terminal portion of hemodialysis grafts effectively suppresses neointimal hyperplasia in a porcine model.

OBJECTIVE: The local delivery of paclitaxel onto a graft has been reported to prevent neointimal hyperplasia. Because more than half of vascular stenoses occur within 3 cm of the venous anastomosis, this study tested the effectiveness of a paclitaxel coating restricted to both ends of the expanded polytetrafluoroethylene (ePTFE) graft to reduce the amount of drug delivered. METHODS: Both ends of ePTFE grafts were coated with paclitaxel at a dose of 0.58 µg/mm(2); the total amount of paclitaxel per graft was 0.66 mg. Paclitaxel-coated hemodialysis grafts 15 cm in length were surgically implanted between the common carotid artery and external jugular vein in female Landrace pigs. The animals were sacrificed 6 weeks after graft placement. Cross sections of the anastomosis sites were analyzed histomorphometrically to measure the ratio of neointimal hyperplasia to the graft area (H/G ratio) and the percentage of luminal stenosis. The experimental results were compared between grafts coated with paclitaxel at the ends only (n = 8), grafts coated over the entire length (n = 6), and uncoated control grafts (n = 6). RESULTS: The mean ± standard error values of the H/G ratios for the arterial anastomosis were 0.82 ± 0.13 (control), 0.41 ± 0.09 (terminal coating), and 0.21 ± 0.04 (whole coating). The values for the venous anastomosis were 0.82 ± 0.12 (control), 0.39 ± 0.11 (terminal coating), and 0.12 ± 0.03 (whole coating). Compared with the uncoated grafts, neointimal hyperplasia was suppressed effectively in the vascular grafts coated terminally with paclitaxel (artery, P = 050; vein, P < .001). However, the suppressive effect was less than that of grafts coated with paclitaxel over the entire length. The percentages of luminal stenosis showed similar tendency to the H/G ratios. CONCLUSIONS: Despite a reduced amount of the drug, paclitaxel coating applied to both ends of the ePTFE hemodialysis grafts effectively suppressed neointimal hyperplasia at the sites of anastomosis.

Hepatoprotective effects of Lycium chinense Miller fruit and its constituent betaine in CCl4-induced hepatic damage in rats.

The hepatoprotective activities of Lycium chinense Miller (LC) fruit extract and its component betaine were investigated under carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. The treatment of LC fruit extract significantly suppressed the increase of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the sera of CCl4 injured rats, and restored the decreased levels of anti-oxidant enzymes such as total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and suppressed the expression of inflammatory mediators including inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-1 and -2. To visualize the potential activity of betaine, a component of LC fruit, betaine was substituted for LC extract in CCl4 injured rats. The biochemical profile in CCl4 injured rats co-treated with betaine matched those of LC fruit treated CCl4 injured rats. The ameliorative effects of LC extract, as well as betaine, were also confirmed by histopathological examination. Collectively, the present findings imply that LC fruit, via its component betaine, mitigate CCl4-induced hepatic injury by increasing antioxidative activity and decreasing inflammatory mediators including iNOS and COX-1/COX-2.

Recombinant soluble neprilysin reduces amyloid-beta accumulation and improves memory impairment in Alzheimer's disease mice.

Accumulation of amyloid-ß (Aß) is thought to be a central pathology in the brain of patients with Alzheimer's disease (AD). Neprilysin (NEP), a plasma membrane glycoprotein of the neutral zinc metalloendopeptidase family, is known as a major Aß-degrading enzyme in the brain. The level of NEP is reduced in the brains of patients with AD; therefore, NEP is under intense investigation as a potential therapeutic source for degradation of deposited Aß in AD. Previous studies have utilized viral vectors expressing NEP for reduction of Aß deposition in the brain. However, viral vectors have disadvantages regarding difficulty in control of insert size, expression desired (short- or long-term), and target cell type. Here, in order to overcome these disadvantages, we produced recombinant soluble NEP from insect cells using an NEP expression vector, which was administered by intracerebral injection into AD mice, resulting in significantly reduced accumulation of Aß. In addition, AD mice treated with NEP showed improved behavioral performance on the water maze test. These data support a role of recombinant soluble NEP in improving memory impairment by regulation of Aß deposition and suggest the possibility that approaches using protein therapy might have potential for development of alternative therapies for treatment of AD.

Nonviral gene therapy in vivo with PAM-RG4/apoptin as a potential brain tumor therapeutic.

BACKGROUND: Glioma is still one of the most complicated forms of brain tumor to remove completely due to its location and the lack of an efficient means to specifically eliminate tumor cells. For these reasons, this study has examined the effectiveness of a nonviral gene therapy approach utilizing a tumor-selective killer gene on a brain tumor xenograft model. METHODS AND RESULTS: The therapeutic apoptin gene was recombined into the JDK plasmid and delivered into human brain tumor cells (U87MG) by using a polyamidoamine dendrimer with an arginine surface (PAM-RG4). Studies in vitro showed that the PAM-RG4/apoptin plasmid polyplex exhibited a particularly high transfection activity of .40%. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, 4',6-Diamidino-2-phenylindole (DAPI) TUNEL assay, DAPI staining, and caspase-3 activity assay verified that the tumor cells had undergone apoptosis induced by apoptin. For in vivo studies, the polyplex was injected into tumors, which were induced by injecting U87MG cells intradermally into nude mice. Based on hematoxylin and eosin staining, epidermal growth factor receptor immunohistochemistry results and tumor volume measurement results, tumor growth was effectively inhibited and no specific edema, irritation, or other harm to the skin was observed after polyplex injection. The in vivo expression of apoptin and the induction of apoptosis were verified by reverse-transcription polymerase chain reaction analysis, TUNEL assay, and DAPI staining. CONCLUSION: The PAM-RG4/apoptin gene polyplex is a strong candidate for brain tumor therapeutics because of the synergistic effect of the carrier's high transfection efficiency (35%-40%) in glioma cells and the selective apoptosis-inducing activity of apoptin in tumor cells.

Arginine modified PAMAM dendrimer for interferon beta gene delivery to malignant glioma.

A xenograft brain tumor model was established by the subcutaneous injection of U87MG cells into nude mice to investigate the efficacy of a non-viral vector, arginine-modified polyamidoamine dendrimer (PAMAM-R), in delivering a therapeutic gene, human interferon beta (IFN-ß). We used 4',6-diamidino-2-phenylindole staining, the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay, and the caspase-3 activity assay to determine the induction of apoptosis upon transfection with the PAMAM-R/IFN-ß gene polyplex in vitro. The polyplex was injected into xenograft brain tumors. Mice treated with PAMAM-R/pORF-IFN-ß exhibited a significantly smaller tumor size than control mice and PAMAM-R/pORF treated mice. Hematoxylin/eosin staining and immunohistochemistry with the endothelial growth factor receptor antibody also revealed inhibition of tumor growth. Furthermore, reverse transcription polymerase chain reaction and the TUNEL assay also verified the expression of IFN-ß and induction of apoptosis in vivo. These results indicate that the PAMAM-R/pORF-IFN-ß polyplex is an effective therapeutic candidate for glioblastoma multiforme due to its selective induction of apoptosis in tumor cells.

Effective healing of diabetic skin wounds by using nonviral gene therapy based on minicircle vascular endothelial growth factor DNA and a cationic dendrimer.

BACKGROUND: The development of an efficient method to improve the wound healing process is urgently required for diabetic patients suffering a threat of limb amputations. Various growth factors have been proposed for treatment; however, more research still has to be carried out to maintain their curative effect. In the present study, we describe a simple nonviral gene therapy method for improving wound healing. METHODS: Minicircle plasmid DNA encoding vascular endothelial growth factor (VEGF) was combined with an arginine-grafted cationic dendrimer, PAM-RG4. The formed complexes were injected subcutaneously into the skin wounds of diabetic mice. RESULTS: Actively proliferating cells in wound tissue were efficiently transfected, resulting in a high level of VEGF expression. Within 6 days after injection, skin wounds in the diabetic mice were generally healed and displayed a well-ordered dermal structure, which was confirmed by histological staining. CONCLUSIONS: This simple and effective gene therapy method may represent a powerful tool for the treatment of diabetic foot ulcers and other diseases that are refractory to treatment.

Intranasal delivery of HMGB1 siRNA confers target gene knockdown and robust neuroprotection in the postischemic brain.

Noninvasive intranasal drug administration has been noted to allow direct delivery of drugs to the brain. In the present study, the therapeutic efficacy of intranasal small interfering RNA (siRNA) delivery was investigated in the postischemic rat brain. Fluorescein isothiocyanate (FITC)-labeled control siRNA was delivered intranasally in normal adult rats using e-PAM-R, a biodegradable PAMAM dendrimer, as gene carrier. Florescence-tagged siRNA was found in the cytoplasm and processes of neurons and of glial cells in many brain regions, including the hypothalamus, amygdala, cerebral cortex, and striatum, in 1 hour after infusion, and the FITC-fluorescence was continuously detected for at least 12 hours. When siRNA for high mobility group box 1 (HMGB1), which functions as an endogenous danger molecule and aggravates inflammation, was delivered intranasally, the target gene was significantly depleted in many brain regions, including the prefrontal cortex and striatum. More importantly, intranasal delivery of HMGB1 siRNA markedly suppressed infarct volume in the postischemic rat brain (maximal reduction to 42.8 ± 5.6% at 48 hours after 60 minutes middle cerebral artery occlusion (MCAO)) and this protective effect was manifested by recoveries from neurological and behavioral deficits. These results indicate that the intranasal delivery of HMGB1 siRNA offers an efficient means of gene knockdown-mediated therapy in the ischemic brain.

Paclitaxel coating of the luminal surface of hemodialysis grafts with effective suppression of neointimal hyperplasia.

OBJECTIVES: Paclitaxel coating of hemodialysis grafts is effective in suppressing neointimal hyperplasia in the graft and vascular anastomosis sites. However, paclitaxel can have unwanted effects on the surrounding tissues. To reduce such problems, we developed a method to coat the drug only on the luminal surface of the graft, with little loading on the outer surface. METHODS: A peristaltic pump and a double-solvent (water and acetone) system were used to achieve an inner coating of paclitaxel. At the ratio of 90% acetone, paclitaxel was homogeneously coated only on the luminal surface of the graft without changing the physical properties. To determine its effect, grafts were implanted between the common carotid artery and the external jugular vein in pigs using uncoated control grafts (n = 6) and low-dose (n = 6, 0.22 µg/mm(2)) and high-dose (n = 6, 0.69 µg/mm(2)) paclitaxel inner-coated grafts. Cross-sections of graft-venous anastomoses were analyzed histomorphometrically 6 weeks after placement to measure the patency rate, percentage of luminal stenosis, and neointimal area. RESULTS: No signs of infection or bacterial contamination were observed in the paclitaxel inner-coated groups. Only one of the six control grafts was patent, but all of the paclitaxel-coated grafts were patent, with little neointima. The mean ± standard error values of percentage luminal stenosis were 75.7% ± 12.7% (control), 17.5% ± 3.1% (low dose), and 19.7% ± 3.0% (high dose). The values for the neointimal area (in mm(2)) were 8.77 ± 1.66 (control), 3.53 ± 0.73 (lose dose), and 4.24 ± 0.99 (high dose). Compared with the control group, paclitaxel inner-coated vascular grafts significantly suppressed neointimal hyperplasia (low dose, P = .001; high dose, P = .002). Myofibroblast proliferation and migration into the graft interstices confirmed the firm attachment of the implanted graft to the surrounding tissue. CONCLUSIONS: Paclitaxel coating on the inner luminal surface of vascular grafts was effective in suppressing neointimal hyperplasia, with little inhibition of myofibroblast infiltration within the graft wall.

Suppression of neointimal hyperplasia by sirolimus-eluting expanded polytetrafluoroethylene (ePTFE) haemodialysis grafts in comparison with paclitaxel-coated grafts.

BACKGROUND: Haemodialysis vascular access dysfunction caused by aggressive venous neointimal hyperplasia is a major problem for haemodialysis patients with synthetic arteriovenous (AV) grafts. Several different strategies to prevent venous stenosis by inhibiting smooth muscle cell proliferation and migration using local delivery of potent antiproliferative agents are currently under investigation. We performed this study to evaluate the efficacy of sirolimus-eluting vascular grafts in preventing stenosis and to compare the effectiveness of sirolimus-coated grafts with that of paclitaxel-coated vascular grafts that we characterized in a previous study. METHODS: AV grafts were implanted laterally between the common carotid artery and external jugular vein of 14 female Landrace pigs. Three types of grafts were implanted: grafts coated with 1.08 µg/mm(2) sirolimus (low dose, n = 6), grafts coated with 2.41 µg/mm(2) sirolimus (high dose, n = 2) and uncoated control grafts (n = 6). Animals were sacrificed 6 weeks after surgery. Cross-sections of the venous anastomoses were analysed to determine the percentage of luminal stenosis in each group, and immunohistochemistry was performed to identify the cellular phenotypes of the neointimal hyperplasia and tissues adjacent to the implanted grafts. RESULTS: Compared with the control group, neointimal hyperplasia in the venous anastomoses of the groups implanted with sirolimus-coated vascular grafts was significantly suppressed without infection. The mean ± standard error values for the percentage of luminal stenosis were 75.7 ± 12.7% in the control group and 22.2 ± 1.41% in the low-dose sirolimus-coated group. Myofibroblasts and fibroblasts were the major cell types found in the neointimal hyperplasia. CONCLUSIONS: Neointimal hyperplasia was effectively suppressed by sirolimus-eluting grafts. However, the inhibitory effects of sirolimus-eluting grafts were weaker than those observed for paclitaxel-coated grafts in our previous study.

Topically administered Risedronate shows powerful anti-osteoporosis effect in ovariectomized mouse model.

We investigated the therapeutic effect of topical Risedronate (RIS) on a mouse model of estrogen-deficient osteoporosis. Fourteen-week-old female mice were ovariectomized and assigned to 4 groups: SHAM-operated (SHAM), OVX mice treated with vehicle (OVX-V), OVX mice treated with 0.2% RIS (OVX-0.2% RIS), and OVX-mice treated with 0.02% RIS (OVX-0.02% RIS). Topical samples containing RIS were prepared in 10% (w/w) polyethylene glycol (PEG, MW 400) and 80 µg of sample was spread on the mice's mid-backs every 3 days for 5 weeks. Micro-CT analysis of femora demonstrated that OVX-0.2% RIS exhibited a 29% greater bone mineral density and 24% greater bone volume fraction than that of OVX-V group. Investigation of the trabecular bone in OVX-0.2% RIS revealed a 24% higher bone volume (BV/TV), 51% higher trabecular number (Tb.N), and 40% lower trabecular separation (Tb.Sp) compared to OVX-V mice. Additionally, bone phenotypes of tibiae were further confirmed by histological analysis. OVX-0.2% RIS group exhibited a 494% greater BV/TV, 464% less Tb.Sp, 81% greater active osteoclast surface (Oc.S/BS) and 26% less osteoclast number (N.Oc/BS) than that of OVX-V group. Collectively, these results indicated that topical delivery of RIS has powerful pharmaceutical effects on the prevention of osteoporosis and bone turnover.

Effect of deoxycholate conjugation on stability of pDNA/polyamidoamine-diethylentriamine (PAM-DET) polyplex against ionic strength.

Polyplexes formed from cationic polymer/pDNA have been known to be vulnerable to external ionic strength. To improve polyplex stability against ionic strength, we attempted the chemical conjugation of the hydrophobic deoxycholate (DC) moiety to the polyamidoamine-diethylenetriamine (PAM-DET) dendrimer. Dynamic light scattering studies showed that the tolerance of the resulting PAM-DET-DC against ionic strength is higher than that of PAM-DET. In addition, we confirmed that the stability of polyplex has a strong relationship with the degree of conjugation of the DC moiety to the PAM-DET dendrimer and the charge ratio of PAM-DET-DC. Furthermore, the transfection efficiency of the PAM-DET-DC polyplex is higher than that of PAM-DET but its cytotoxicity remains the same. Therefore, the chemical conjugation of DC is a safe and effective method for increasing the stability of supramolecules formed from electrostatic interaction.

Ion pairs of risedronate for transdermal delivery and enhanced permeation rate on hairless mouse skin.

Ion-paired solutions of risedronate (RIS) with L-arginine (ARG), L-lysine (LYS), and diethylenetriamine (DETA) were tested in vitro for their potential to enhance the penetration of RIS across the skin of hairless mouse. The xylene solubilities of RIS paired with ARG, LYS, and DETA in molar ratios of 1:2, 1:2, and 1:1 were 8.9%, 12.0%, and 2.1%, respectively, in comparison with the solubility in deionized water, but non-ion-paired RIS was not detected in xylene. In vitro permeation tests were performed on the skin of hairless mice, and the results indicated that ion-paired RIS could penetrate mice skin about 36 times more effectively than RIS alone. The cumulative amount of ion paired RIS after 24 h resulted in 475.18±94.19 µg/cm(2) and 511.21±106.52 µg/cm(2) at molar ratio of 1:2 and 1:1. The cumulative amount of RIS alone was as low as 14.13±5.49 µg/cm(2) in 24h. The hairless mice showed no skin irritation after a single administration of RIS alone and ion-paired RIS (1:2 molar ratio with ARG, and 1:1 molar ratio with DETA). In this study, we found that RIS can be delivered transdermally, and the ion-paired system in an aqueous solution showed an enhanced flux through the skin barrier.

Nonviral gene delivery to human ovarian cancer cells using arginine-grafted PAMAM dendrimer.

BACKGROUND: A specific and effective strategy is in demand to treat ovarian cancer successfully. Epidermal growth factor receptor (EGFR) is highly expressed in ovarian cancer, and thus EGFR antisense gene therapy can be a potential therapeutic strategy. METHOD: L-Arginine-grafted-polyamidoamine dendrimer (PAMAM-Arg) has been reported to be a novel nonviral gene delivery carrier. Therefore, the ability of PAMAM-Arg in transferring a luciferase gene to ovarian carcinoma SK-OV3 cells has been examined, and the cytotoxicity of the cationic polymer has been investigated. In addition, the suppression of cell proliferation has been evaluated by transferring an EGFR antisense gene to SK-OV3 cells using PAMAM-Arg. Polyethyleneimine (PEI) 25K was used as a positive control. RESULTS: As a result, in vitro gene transfection efficiency of PAMAM-Arg was enhanced with increasing transfection time and N/P ratios. PAMAM-Arg transferred the luciferase gene into cells more efficiently than PEI. In addition, PAMAM-Arg was minimally toxic to the cells whereas PEI 25K was highly toxic. The polyplexes formed by the EGFR antisense gene and PAMAM-Arg significantly reduced thymidine incorporation into the cells suggesting the suppression of cancer cell proliferation. CONCLUSION: These results suggest that a PAMAM-Arg/EGFR antisense gene complex can be used as a safe and efficient therapeutic agent for cancer gene therapy.

Suppression of hepatitis C virus genome replication in cells with RNA-cleaving DNA enzymes and short-hairpin RNA.

A class of antisense oligodeoxyribozymes, known as the 10-23 DNA enzymes (DNAzyme), has been shown to efficiently cleave target RNA at purine-pyrimidine junctions in vitro. Herein we have utilized a strategy to identify accessible cleavage sites for DNAzyme in the target RNA, the hepatitis C virus nonstructural gene 3 (HCV NS3) RNA that encodes viral helicase and protease, from a pool of randomized DNAzyme library. The screening procedure identified 18 potential cleavage sites in the target RNA. Corresponding DNAzymes were constructed for the selected target sites and were tested for RNA cleavage in vitro. Using positively charged dendrimer nanoparticles, the target RNA-cleaving DNAzymes that are 31-mer oliogonucleotides are delivered into the human hepatoma cells harboring the HCV subgenomic replicon RNA. DNAzymes introduced into the cells efficiently inhibited HCV RNA replication by reducing the expression of HCV NS3. In addition, we designed short-hairpin RNA (shRNA) that targets the same cleavage site for the selected DNAzyme and confirmed that the shRNA also inhibited HCV NS3 gene expression in the HCV replicon cells. These selected DNAzyme and shRNA may be a viable therapeutic intervention to inhibit HCV replication in hepatic cells. We suggest that the method used in this study can be applicable for identification of available sites in any target RNA for antisense oligonucleotides and siRNAs.

Cytoprotective effect of the fruits of Lycium chinense Miller against oxidative stress-induced hepatotoxicity.

AIM OF THE STUDY: Fruits of Lycium chinense Miller (Solanaceae), distributed in northeast Asia, have gained attraction for their hepatoprotective role in traditional oriental medicine. The excessive production of reactive oxygen species (ROS) is hazardous for living organisms and damage major cellular constituents such as DNA, lipid, and protein. The cytoprotective effect of Lycium chinense fruits (Lycium extract) was assessed against H(2)O(2)-induced Chang liver cell damage. MATERIALS AND METHODS: The effect of Lycium extract against H(2)O(2)-induced cell death was determined by the MTT assay. Radical scavenging activity was determined through the assessments of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, intracellular ROS, hydroxyl radicals, and superoxide. The inductions of antioxidant enzymes were determined via their protein expressions and activities. DNA damage was measured using comet assay and expression of phospho-histone H2A.X. Lipid peroxidation was measured using 8-isoprostane level and fluorescent probe. Protein modification was measured using protein carbonyl moiety. RESULTS AND CONCLUSION: Lycium extract scavenged the DPPH free radicals, intracellular ROS, hydroxyl radicals, and superoxide. Lycium extract recovered activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) decreased by H(2)O(2). Lycium extract decreased DNA damage, lipid peroxidation and protein carbonyl values increased by H(2)O(2) exposure. In addition, Lycium extract increased the cell viability of Chang liver cells exposed to H(2)O(2) via inhibition of apoptosis. These results show that Lycium extract protected Chang liver cells against oxidative stressed cell damage by H(2)O(2) via scavenging ROS and enhancing antioxidant enzyme activity.