Genetically reprogrammed, liver-derived insulin-producing cells are glucose-responsive, but susceptible to autoimmune destruction in settings of murine model of type 1 diabetes.

Many previous studies demonstrate that hepatocytes can be reprogrammed into insulin-producing cells (IPCs) utilizing viral vector-mediated delivery of pancreatic transcription factors (PTFs). However, whether these liver-derived IPCs are susceptible to autoimmune attack in animal models of type 1 diabetes remains unclear, in part due to the immunogenicity of the viral vectors used to introduce PTF genes. Adeno-associated virus serotype 2 vector-expressing Pdx1-VP16 (Pdx1) and Ngn3 were prepared and injected into the portal vein of streptozotocin (Stz)/diabetic NOD/SCID mice. The presence of glucose-responsive liver-IPCs and their susceptibility to anti-beta cell autoimmunity were assessed by blood glucose levels, insulin content, IPC cell distribution, and intraperitoneal glucose tolerance test following subtotal pancreatectomy (Px) and passive transfer of diabetogenic splenocytes isolated from diabetic female NOD mice. A combination of two PTF genes (Pdx1/Ngn3) effectively reprogrammed liver cells into glucose-responsive IPCs. These IPCs corrected hyperglycemia in Stz/diabetic NOD/SCID mice and maintained normoglycemia following subtotal Px, indicating that liver-derived IPCs could maintain glucose homeostasis. Importantly, we also demonstrated that the glucose-responsive liver-derived IPCs were susceptible to autoimmune destruction by diabetogenic splenocytes, as indicated by progressive elevation in blood glucose levels as well as mixed T-, and B-lymphocytic infiltrates surrounding liver-IPCs 2~3 weeks following transferring of diabetogenic splenocytes into NOD/SCID mice, and confirmed by immunohistochemical studies. In conclusion, genetically reprogrammed liver-IPCs, like pancreatic islet beta-cells, are susceptible to autoimmune attack, suggesting that for cell-replacement therapy of treating type 1 diabetes, beta-cell surrogates may require concomitant immunotherapy to avoid autoimmune destruction.

A novel two-step procedure to expand cardiac Sca-1+ cells clonally.

Resident cardiac stem cells (CSCs) are characterized by their capacity to self-renew in culture, and are multipotent for forming normal cell types in hearts. CSCs were originally isolated directly from enzymatically digested hearts using stem cell markers. However, long exposure to enzymatic digestion can affect the integrity of stem cell markers on the cell surface, and also compromise stem cell function. Alternatively resident CSCs can migrate from tissue explant and form cardiospheres in culture. However, fibroblast contamination can easily occur during CSC culture. To avoid these problems, we developed a two-step procedure by growing the cells before selecting the Sca-1+ cells and culturing in cardiac fibroblast conditioned medium, they avoid fibroblast overgrowth.

Efficient and persistent transduction of exocrine and endocrine pancreas by adeno-associated virus type 8.

Efficient delivery of therapeutic proteins into the pancreas represents a major obstacle to gene therapy of pancreatic disorders. The current study compared the efficiency of recombinant lentivirus and adeno-associated virus (AAV) serotypes 1, 2, 5, 8 vectors delivered by intrapancreatic injection for gene transfer in vivo. Our results indicate that lentivirus and AAV 1, 2, 8 are capable of transducing pancreas with the order of efficiency AAV8 >>AAV1 > AAV2 >/= lentivirus, whereas AAV5 was ineffective. AAV8 resulted in an efficient, persistent (150 days) and dose-dependent transduction in exocrine acinar cells and endocrine islet cells. Pancreatic ducts and blood vessels were also transduced. Extrapancreatic transduction was restricted to liver. Leukocyte infiltration was not observed in pancreas and blood glucose levels were not altered. Thus, AAV8 represents a safe and effective vehicle for therapeutic gene transfer to pancreas in vivo.

Specific beta1-adrenergic receptor silencing with small interfering RNA lowers high blood pressure and improves cardiac function in myocardial ischemia.

OBJECTIVES: Beta-blockers are widely used and effective for treating hypertension, acute myocardial infarction (MI) and heart failure, but they present side-effects mainly due to antagonism of beta2-adrenergic receptor (AR). Currently available beta-blockers are at best selective but not specific for beta1 or beta2-AR. METHODS: To specifically inhibit the expression of the beta1-AR, we developed a small interfering RNA (siRNA) targeted to beta1-AR. Three different sequences of beta1 siRNA were delivered into C6-2B cells with 90% efficiency. RESULTS: One of the three sequences reduced the level of beta1-AR mRNA by 70%. The siRNA was highly specific for beta1-AR inhibition with no overlap with beta2-AR. To test this in vivo, systemic injection of beta1 siRNA complexed with liposomes resulted in efficient delivery into the heart, lung, kidney and liver, and effectively reduced beta1-AR expression in the heart without altering beta2-AR. beta1 siRNA significantly lowered blood pressure of spontaneously hypertensive rats (SHR) for at least 12 days and reduced cardiac hypertrophy following a single injection. Pretreatment with beta1 siRNA 3 days before induction of MI in Wistar rats significantly improved cardiac function, as demonstrated by dP/dt and electrocardiogram following the MI. The protective mechanism involved reduction of cardiomyocyte apoptosis in the beta1 siRNA-treated hearts. CONCLUSIONS: The present study demonstrates the possibility of using siRNA for treating cardiovascular diseases and may represent a novel beta-blocker specific for beta1-AR.

Efficient delivery of siRNA into cytokine-stimulated insulinoma cells silences Fas expression and inhibits Fas-mediated apoptosis.

Fas/FasL interactions have been proposed as a potentially important mechanism mediating beta-cell death in type 1 diabetes. Recent investigations suggest RNA interference, afforded by small interfering RNAs (siRNA), can provide specific and robust gene silencing in mammalian cells. The current study attempted to investigate the effects of silencing Fas expression with siRNA on Fas-mediated apoptosis in mouse insulinoma cells following cytokine incubation. Our results indicate that siRNA is capable of rapid inhibition of cytokine-induced Fas mRNA production and cell surface Fas protein. A complete suppression of the total Fas protein was only observed after prolonged incubation with siRNA, suggesting a slow turn-over of Fas protein. Moreover, siRNA significantly inhibited Fas-mediated beta-cell apoptosis assessed by Caspase-3 and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling assays, the extent of which positively correlated with the level of cell surface Fas. These observations provide additional evidence supporting a role for the Fas-mediated pathway in beta-cell destruction, and suggest that siRNA targeting Fas may be of therapeutic value in preventing type 1 diabetes and improving islet cell viability in transplantation.

A vigilant, hypoxia-regulated heme oxygenase-1 gene vector in the heart limits cardiac injury after ischemia-reperfusion in vivo.

OBJECTIVES: The effect of a cardiac specific, hypoxia-regulated, human heme oxygenase-1 (hHO-1) vector to provide cardioprotection from ischemia-reperfusion injury was assessed. BACKGROUND: When myocardial ischemia and reperfusion is asymptomatic, the damaging effects are cumulative and patients miss timely treatment. A gene therapy approach that expresses therapeutic genes only when ischemia is experienced is a desirable strategy. We have developed a cardiac-specific, hypoxia-regulated gene therapy "vigilant vector'' system that amplifies cardioprotective gene expression. METHODS: Vigilant hHO-1 plasmids, LacZ plasmids, or saline (n = 40 per group) were injected into mouse heart 2 days in advance of ischemia-reperfusion injury. Animals were exposed to 60 minutes of ischemia followed by 24 hours of reperfusion. For that term (24 hours) effects, the protein levels of HO-1, inflammatory responses, apoptosis, and infarct size were determined. For long-term (3 week) effects, the left ventricular remodeling and recovery of cardiac function were assessed. RESULTS: Ischemia-reperfusion resulted in a timely overexpression of HO-1 protein. Infarct size at 24 hours after ischemia-reperfusion was significantly reduced in the HO-1-treated animals compared with the LacZ-treated group or saline-treated group (P < .001). The reduction of infarct size was accompanied by a decrease in lipid peroxidant activity, inflammatory cell infiltration, and proapoptotic protein level in ischemia-reperfusion-injured myocardium. The long-term study demonstrated that timely, hypoxia-induced HO-1 overexpression is beneficial in conserving cardiac function and attenuating left ventricle remodelling. CONCLUSIONS: The vigilant HO-1 vector provides a protective therapy in the heart for reducing cellular damage during ischemia-reperfusion injury and preserving heart function.

Improved graft mesenchymal stem cell survival in ischemic heart with a hypoxia-regulated heme oxygenase-1 vector.

OBJECTIVES: The goal of this study was to modify mesenchymal stem cells (MSCs) cells with a hypoxia-regulated heme oxygenase-1 (HO-1) plasmid to enhance the survival of MSCs in acute myocardial infarction (MI) heart. BACKGROUND: Although stem cells are being tested clinically for cardiac repair, graft cells die in the ischemic heart because of the effects of hypoxia/reoxygenation, inflammatory cytokines, and proapoptotic factors. Heme oxygenase-1 is a key component in inhibiting most of these factors. METHODS: Mesenchymal stem cells from bone marrow were transfected with either HO-1 or LacZ plasmids. Cell apoptosis was assayed in vitro after hypoxia-reoxygen treatment. In vivo, 1 x 10(6) of male MSC(HO-1), MSC(LacZ), MSCs, or medium was injected into mouse hearts 1 h after MI (n = 16/group). Cell survival was assessed in a gender-mismatched transplantation model. Apoptosis, left ventricular remodeling, and cardiac function were tested in a gender-matched model. RESULTS: In the ischemic myocardium, the MSC(HO-1) group had greater expression of HO-1 and a 2-fold reduction in the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling-positive cells compared with the MSC(LacZ) group. At seven days after implantation, the survival MSC(HO-1) was five-fold greater than the MSC(LacZ) group; MSC(HO-1) also attenuated left ventricular remodeling and enhanced the functional recovery of infarcted hearts two weeks after MI. CONCLUSIONS: A hypoxia-regulated HO-1 vector modification of MSCs enhances the tolerance of engrafted MSCs to hypoxia-reoxygen injury in vitro and improves their viability in ischemic hearts. This demonstration is the first showing that a physiologically inducible vector expressing of HO-1 genes improves the survival of stem cells in myocardial ischemia.

Mobilizing of haematopoietic stem cells to ischemic myocardium by plasmid mediated stromal-cell-derived factor-1alpha (SDF-1alpha) treatment.

A concentration gradient of stromal-cell-derived factor-1alpha (SDF-1alpha) is the major mechanism for homing of haematopoietic stem cells (HSCs) in bone marrow. We tested the hypothesis that a gene therapy using SDF-1alpha can enhance HSCs recruiting to the heart upon myocardial infarction (MI). Adult mice with surgically induced myocardial ischemia were injected intramyocardially with either saline (n=12) or SDF-1alpha plasmid (n=12) in 50 microl volume in the ischemic border zone of the infarcted heart 2 weeks after myocardial infarction. Donor Lin-c-kit+ HSCs from isogenic BalB/c mice were harvested, sorted through magnetic cell sorting (MACS) and labeled with PKH26 Red. Three days after plasmid or saline injection, 1x10(5) labeled cells were injected intravenously (i.v.) into saline mice (n=4) and SDF-1alpha plasmid mice (n=4). The hearts and other tissue were removed for Western blot assay 2 weeks after plasmid or saline treatment. The labeled Lin-c-kit+ cells were identified with immunofluoresent staining and endogenous c-kit+ cells were identified by immunohistochemical staining. In mice killed at 1 month postinfarct, Western blot showed higher levels of SDF-1alpha expression in SDF-1alpha-treated mouse ischemic hearts compared to saline-treated hearts and other tissues. In the SDF-1alpha plasmid-treated hearts, SDF-1alpha is overexpressed in the periinfarct zone. The labeled stem cells engrafted to the SDF-1alpha positive site in the myocardium. There was also evidence for endogenous stem cell recruiting. The density of c-kit+ cells in border zone, an index of endogenous stem cell mobilization, was significantly higher in the SDF-1alpha-treated group than in the saline group (14.63+/-1.068 cells/hpf vs. 11.31+/-0.65 cells/hpf, P=0.013) at 2 weeks after SDF-1alpha or saline treatment. Following myocardial infarction, treatment with SDF-1alpha recruits stem cells to damaged heart where they may have a role in repairing and regeneration. The gene therapy with an SDF-1alpha vector offers a promising therapeutic strategy for mobilizing stem cells to the ischemic myocardium.

Protection from ischemic heart injury by a vigilant heme oxygenase-1 plasmid system.

Although human heme oxygenase-1 (hHO-1) could provide a useful approach for cellular protection in the ischemic heart, constitutive overexpression of hHO-1 may lead to unwanted side effects. To avoid this, we designed a hypoxia-regulated hHO-1 gene therapy system that can be switched on and off. This vigilant plasmid system is composed of myosin light chain-2v promoter and a gene switch that is based on an oxygen-dependent degradation domain from the hypoxia inducible factor-1-alpha. The vector can sense ischemia and switch on the hHO-1 gene system, specifically in the heart. In an in vivo experiment, the vigilant hHO-1 plasmid or saline was injected intramyocardially into myocardial infarction mice or sham operation mice. After gene transfer, expression of hHO-1 was only detected in the ischemic heart treated with vigilant hHO-1 plasmids. Masson trichrome staining showed significantly fewer fibrotic areas in vigilant hHO-1 plasmids-treated mice compared with saline control (43.0%+/-4.8% versus 62.5%+/-3.3%, P<0.01). The reduction of interstitial fibrosis is accompanied by an increase in myocardial hHO-1 expression in peri-infarct border areas, concomitant with higher Bcl-2 levels and lower Bax, Bak, and caspase 3 levels in the ischemic myocardium compared with saline control. By use of a cardiac catheter, heart from vigilant hHO-1 plasmids-treated mice showed improved recovery of contractile and diastolic performance after myocardial infarction compared with saline control. This study documents the beneficial regulation and therapeutic potential of vigilant plasmid-mediated hHO-1 gene transfer. This novel gene transfer strategy can provide cardiac-specific protection from future repeated bouts of ischemic injury.

Antisense to epidermal growth factor receptor prevents the development of left ventricular hypertrophy.

We previously demonstrated that left ventricular hypertrophy (LVH) induced by angiotensin II infusion requires epidermal growth factor receptor (EGFR) activation to mediate the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. To test whether the EGFR-mediated MAPK/ERK activation plays an important role in development and maintenance of LVH in spontaneously hypertensive rats (SHR), we investigated the effects of antisense oligodeoxynucleotide to EGFR (EGFR-AS) on LVH and blood pressure in young and adult SHR. EGFR-AS, sense oligonucleotide to EGFR (EGFR-S; 1.5 mg/kg), or vehicle control (5% dextrose) with liposome was injected once a week for 2 months in 5- or 13-week-old SHR. The effect of EGFR-AS on the expression of EGFR and phosphorylated ERK in the heart were examined by Western blots. After treatment, EGFR-AS significantly (P<0.05) decreased left ventricular weight/body weight and blood pressure in young SHR compared with EGFR-S or control-treated rats. In adult SHR, EGFR-AS did not affect left ventricular weight/body weight and blood pressure. EGFR and phosphorylated ERK significantly declined from 5 to 20 weeks (P<0.05). EGFR-AS, but not EGFR-S, significantly (P<0.05) decreased the expression of EGFR and phosphorylated ERK in young SHR, but had no significant effect in adult SHR. These results suggests that EGFR-mediated ERK activation is critically important for LVH in young SHR. This may be related to the high levels of EGFR and phosphorylated ERK in young SHR, suggesting a critical role of the EGFR-activated ERK pathway in cardiovascular development but not in the maintenance of established LVH in adult SHR.

Presenilins in the heart: presenilin-2 expression is increased by low glucose and by hypoxia in cardiac cells.

Cardiac cells are subjected to hypoxia in many cardiovascular diseases. We studied a broad spectrum of genes using a macroarrays-based method to analyze RNA of rat cardiac fetal cell line H9c2 after 4 h of hypoxic conditions in the incubator-1% oxygen concentration, as compared to normoxic conditions (21% oxygen). The cDNAs were prepared from total RNAs using Atlas Rat 1.2 Array (Clontech Laboratories) and hybridized to the membrane containing 1176 rat cDNAs and 9 housekeeping control cDNAs. Genes expression was analyzed using AtlasImage 1.01 software. We found over 45 genes up-regulated in a range of 1.5-2.9 times and 9 genes down-regulated to a range of 0.4-0.7 times, under hypoxia versus normoxia. Presenilin-2 (PS2) was detected in the cultured heart cells. RT-PCR confirmed the presence of PS2 in the heart of adult rats. Using quantitative real-time RT-PCR, we further studied the expression of presenilin-2 mRNA under conditions of low oxygen supply and glucose starvation. Glucose deprivation itself caused significant up-regulation of the presenilin-2 (to 160%) and with low oxygen increased presenilin-2 level to over 200% of the control. Presenilin-2 has previously been associated with intercellular signaling in the central nervous system, in Alzheimer's disease. The finding of presenilin-2 in the heart and the responsiveness to low glucose and hypoxia suggests that PS2 may be regulated by conditions of ischemia, a condition which both the heart and brain may experience.

Vigilant vectors: adeno-associated virus with a biosensor to switch on amplified therapeutic genes in specific tissues in life-threatening diseases.

There are many life-threatening and chronic diseases in which physiological signals could be used to switch on therapeutic protective genes. We are developing a gene therapy approach in which a systemically injected "vigilant vector" waits for these signals and switches on genes to protect specific tissues with high amplification. The concept of a vigilant vector requires four components. The first component is a safe and stable vector that can be administered by systemic injection and express transgenes in a particular organ or tissue. The adeno-associated virus vector is safe and stable for this purpose. The second component is a reversible gene switch which is a biosensor that can detect certain physiological signals. We are developing a hypoxia switch, based on the oxygen-dependent degradation domain of hypoxia-inducible factor. The third component is a tissue-specific promoter, and we have used the myosin light-chain-2V promoter for specific expression in the heart. The fourth component is an amplification system. For this we have developed a double-plasmid/vector system based on the yeast GAL4 and human transcriptional activator p65 to produce a transactivating fusion protein that binds to a GAL4 activation sequence in an activating plasmid that then expresses high levels of cardioprotective genes.

[Relationship between diversity of hepatitis C virus quasispecies and viremia, activity of liver disease and response to interferon therapy].

BACKGROUND: To determine the relationship between diversity of hepatitis C virus quasispecies and viremia, activity of liver disease and response to interferon therapy. METHODS: HCV quasispecies heterogeneity in 68 patients with chronic hepatitis C were detected by single stranded conformational polymorphism (SSCP) analysis of the HCV E2 hypervaribale region 1 (HVR1); of these, 48 were subsequently treated with interferon-alpha for 6 months. RESULTS: HVR1 was amplified in 61 patients. The average number of SSCP bands was 6.2+/-2.4. Quasispecies heterogeneity significantly correlated with serum HCV RNA levels (P<0.01), but not with serum ALT, AST levels and histological activity index (P>0.05). Of the patients who received interferon therapy, 43 were HVR1 positive. Patients who gained sustained response (n=11) had lower pre-treatement quasispecies heterogeneity (3.3+/-1.2) compared to those who had complete end-of-treatment response (ETR) with relapse (6.3+/-2.2, n=12, P<0.5) or no response (8.0+/-3.3, n=20, P<0.01). At the end of treatment, HVR1 could still be detected in 16 patients. The number of quasispecies heterogeneity in these patients decreased to 3.4+/-1.2, which was significantly lower than that in the patients who didn't receive interferon therapy (6.8+/-2.5, P<0.01). Of these 16 patients, 10 had change in quasispecies patterns. CONCLUSIONS: Increased quasispecies heterogeneity can cause high HCV viremia, but it is not related to severity of liver disease. Quasispecies heterogeneity is another marker to predict the response to interferon-alpha in patients with chronic hepatitis C.

Vigilant vector: heart-specific promoter in an adeno-associated virus vector for cardioprotection.

Repeated bouts of ischemia in the heart lead to fibrosis and eventually to heart failure. Although certain genes, such as SOD or hemoxygenase and antisense to AT(1)R, ACE, and (beta(1)-AR can provide short-term protection of the heart from ischemia, there is no known mechanism for constantly responding to repeated incidences of ischemia. We hypothesized that a "vigilant vector," designed to be expressed specifically in the heart and switch on therapeutic genes only during hypoxia, would provide cardioprotection. To attain cardiac specificity, we inserted an MLC2v promoter into an adeno-associated virus (AAV) designed to deliver AS to AT(1)R and gfp. In in vitro experiments in cardiomyocytes (H9C2 cells), the MLC2v-AAV-gfp drove gene expression in all cells at levels comparable to a cytomegalovirus (CMV) promoter. In in vivo experiments, the rAAV-MLC2v-gfp was injected intravenously into mice or rats. Green fluorescence protein (GFP) DNA was located in kidney, heart (right and left ventricle), lung, adrenal and spleen. GFP mRNA, however, was expressed only in the heart and absent in other tissues. To switch on the rAAV transgene during ischemia, we inserted a hypoxia response element (HRE). This upregulates transcription when O(2) levels are low. Thus, there are 4 components to the vigilant vector; a gene switch (HRE), a heart-specific promoter (MLC2v), a therapeutic gene (AS-AT(1)R) and a reporter gene (gfp). To silence or lower basal level of expression while retaining specificity, we have reduced the length of the MLC2v promoter from 3 kb to 1775 bp or 281 bp. The truncated promoter is equally effective in heart specific expression. Preliminary studies with the rAAV-HRE-gfp in vitro show an increased expression in 1% O(2) in 4 to 6 hours. By adding additional hypoxia-inducible factor (HIFalpha) (5 microg), the MLC2v-gfp expression is increased by 4-fold in 1% O(2). Further amplification of the gene to 400-fold in 1% O(2) can be achieved with a double plasmid. The construct may serve as a prototype "vigilant vector" to switch on therapeutic genes in specific tissue with physiological signals.

Hypoxia inducible double plasmid system for myocardial ischemia gene therapy.

Coronary artery disease frequently involves repeated bouts of myocardial ischemia. To automatically up-regulate the cardioprotective transgenes under hypoxic ischemia, a "vigilant vector" gene therapy system was developed and tested in a rat embryonic myocardial cell line (H9c2). In the vigilant vector, a hypoxia response element-incorporated promoter was used as a switch to turn on the gene expression in response to hypoxic signal. Furthermore, a novel double plasmid system was designed to elevate the potency of the vigilant vector. Instead of putting the promoter and the reporter gene in the same plasmid (single plasmid system), we separated them into two plasmids: the transactivator plasmid and reporter plasmid (double plasmid system). The hypoxia response element (HRE)-incorporated promoter increased the expression of a chimeric transcription factor consisting of the yeast GAL4 DNA binding domain and the human nuclear (transcription) factor-kappaB (NF-kappaB) p65 activation domain. The powerful chimeric regulator binds specifically to the upstream activating sequence for GAL4 in the reporter plasmid and activates the transcription of the transgene. Our experiments showed that the HRE-mediated expression could quickly increase 2.08 +/- 0.75-fold within 6 hours of hypoxia and further augmented 7.12 +/- 1.52-fold when the hypoxia condition was prolonged to 24 hours. The hypoxia-inducible double plasmid system dramatically amplified the transgene expression under both hypoxia and normoxia by 412.79 +/- 185.27-fold and 205.35 +/- 65.44-fold, respectively, relative to the single plasmid system. From these results, we concluded that this hypoxia inducible double plasmid system could be used therapeutically to switch on genes that have proven beneficial effects in myocardial ischemia.