Lipid A-like molecules that antagonize the effects of endotoxins on human monocytes

Lipopolysaccharide (LPS) endotoxin is implicated as the bacterial product responsible for the clinical syndrome of Gram-negative septicemia. Although the lipid A domain of LPS appears to be responsible for the toxicity of endotoxin, lipid A from the photosynthetic bacterium Rhodobacter sphaeroides (RSLA) and a disaccharide precursor of lipid A from enteric bacteria, termed lipid IVA, have little activity on human cells. Using the human promonomyelocytic cell line THP-1 and human monocytic cells, we now show that both lipid IVA and RSLA are antagonists of LPS. Complete, apparently competitive, inhibition of LPS activity is possible at a 10-100-fold excess of antagonist, as judged by measuring the release of cytokines and prostaglandin E2. Both antagonists prevent monocyte stimulation by endotoxin extracted from a variety of Gram-negative bacteria. Cells pretreated with either inhibitor and subsequently washed still show attenuated responses to LPS. Stimulation of monocytes by whole Gram-negative bacteria is also antagonized in a dose-dependent manner. Lipid X has no inhibitory effect in the same dose range as lipid IVA and RSLA. These findings rule out LPS sequestration as the explanation for the observed antagonism. Neither inhibitor alters monocyte stimulation by phorbol 12-myristate 13-acetate, Staphylococcus aureus, or purified protein derivative, demonstrating specificity for LPS. Although RSLA appears to inhibit LPS when tested with macrophages from both humans and mice, lipid IVA had the unique ability to act as an LPS antagonist with human-derived cells but to exhibit LPS-like effects with murine-derived cells. Like LPS, lipid IVA stimulated the release of both tumor necrosis factor alpha and arachidonic acid from murine-derived RAW 264.7 macrophage tumor cells. The range of concentrations necessary for lipid IVA to induce LPS-like effects in murine cells was similar to that necessary to antagonize the actions of LPS in human monocytes. The agonist activities of lipid IVA were completely inhibitable by RSLA. This unique species-dependent pharmacology observed with lipid IVA may reflect differences between human and murine LPS receptors. RSLA and lipid IVA may be useful in defining the role of LPS in Gram-negative bacterial infections and may prove to be prototypical therapeutic agents for the treatment of Gram-negative septicemia.     

Cytokine combinations in immunotherapy for solid tumors: a review

The use of cytokines alone or in combination with other cytokines or cytotoxic drugs has had a profound effect upon widely metastatic disease in many cases. However, despite the encouraging results in early trials, there is much room for improvement. Few responses to these combinations are complete, and toxicity has in some cases been quite severe. Changes in dose, route, or schedule of administration of the drugs, or the development of cytokine analogs may lead to more efficacious and less toxic regimens. In addition, new cytokines such as interleukin (IL)-7 and IL-12 are currently under investigation for potential use in future immunotherapy trials. These prospects and the use of cytokine combinations are promising advances in the treatment of human cancer.     

Tissue TGF-β expression following conventional radiotherapy and pulsed low-dose-rate radiation

The release of inflammatory cytokines has been implicated in the toxicity of conventional radiotherapy (CRT). Transforming growth factor β (TGF-β) has been suggested to be a risk marker for pulmonary toxicity following radiotherapy. Pulsed low-dose rate radiotherapy (PLDR) is a technique that involves spreading out a conventional radiotherapy dose into short pulses of dose with breaks in between to reduce toxicities. We hypothesized that the more tolerable toxicity profile of PLDR compared with CRT may be related to differential expression of inflammatory cytokines such as TGF-β in normal tissues. To address this, we analyzed tissues from mice that had been subjected to lethal doses of CRT and PLDR by histology and immunohistochemistry (IHC). Equivalent physical doses of CRT triggered more cellular atrophy in the bone marrow, intestine, and pancreas when compared with PLDR as indicated by hematoxylin and eosin staining. IHC data indicates that TGF-β expression is increased in the bone marrow, intestine, and lungs of mice subjected to CRT as compared with tissues from mice subjected to PLDR. Our in vivo data suggest that differential expression of inflammatory cytokines such as TGF-β may play a role in the more favorable normal tissue late response following treatment with PLDR.     

Age-dependent effects on biochemical variables and toxicity induced by cyclic peptide toxin microcystin-LR in mice

Microcystins are naturally occurring hepatotoxins produced by certain strains of Microcystis aeruginosa and microcystin-LR is the most toxic among the 60 microcystin variants isolated so far. These toxins have been implicated in both human and livestock mortality. In the present study we evaluated the age-dependent hepatotoxic effects of microcystin-LR (MC-LR) in mice after intraperitoneal and oral route of exposure. For acute toxicity studies by intraperitoneal route, 1 LD(50) dose of MC-LR (43.0 microg/kg) was administered to 6- to 36-week-old mice. Results showed that time to death in toxin treated animals decreased with age of mice. In comparison to control mice, treated animals of all age groups showed significant increases in liver body mass index and increases in serum enzymes (lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, sorbitol dehydrogenase). For acute oral toxicity studies, 1 LD(50) of microcystin-LR containing extracts (3.5 g of MCE/kg) was administered to 6- and 36-week-old mice. The effects on biochemical variables were similar to intraperitoneal route of exposure. Significant age-dependent effects that were observed in microcystin treated animals by intraperitoneal and oral routes of exposure include: time to death, hepatic lipid peroxidation, glutathione depletion and DNA fragmentation. The age-dependent effects observed in some of the biochemical variables may be due to difference in the amount of microcystin-LR up take and also the age-dependent ability to detoxify the toxin in mice.     

Acute toxicity of bisphenol A in rats

Bisphenol A (BPA), an estrogenic compound, is used in manufacturing plastics and is known to produce toxic effects on various systems in man and animals. Since the use of plastics in day-to-day life is increasing, exposure to BPA will also increase. Therefore, this study was undertaken to determine the median lethal dose (LD50) of BPA via intraperitoneal and intravenous route in adult rats (by Dixon's up and down method) and also to know the acute systemic changes (in blood pressure, respiration and ECG) produced by lethal dose of BPA. Adult female albino rats of Charles Foster strain were used in the study. LD50 of BPA was 841 and 35.26 mg/kg body weight for ip and iv route, respectively. Injection of lethal dose of BPA (40 mg/kg body weight) produced acute toxicity manifesting as immediate respiratory arrest and hypotension after the injection of BPA followed by bradycardia. The animals died within 7.3 +/- 0.7 min. Volume of ethanol (vehicle; 0.1 mL) present in the lethal dose of BPA was not lethal and had no effect on respiration, blood pressure and heart rate. The results provide evidence that the acute exposure to BPA produces lethality with a very narrow range of lethal and survival dose for iv route. Further, the lethality appears to be due to respiratory arrest and hypotension.     

Balance between pro- and anti-inflammatory cytokines in mice treated with Centruroides noxius scorpion venom

CSV consists of a very complex of molecules and demonstrates significant cellular activities capable of stimulating immune functions in vivo. The purpose of this study was to analyze the effects of CSV on sex, weight, route of injection and the balance of pro- and anti-inflammatory cytokines in mice. The susceptibility and route of injection were analyzed by lethal (LD(50)) determination. The effects of CSV were also analyzed in blood from immunized mice using detection by means of antibodies and mediators production. Several functional bioassays were employed: TNF activity was assayed by measuring its cytotoxic activity in L929 cells, and other cytokines were assayed by enzyme-linked immunosorbent assay, whereas nitric oxide levels were detected by Griess colorimetric reactions in sera from BALB/c mice. After injecting subcutaneously, the LD(50) presented an increase of the CSV correlation and similar levels of susceptibility were obtained for female and male from BALB/c mice. Significant differences were observed in the time-course of cytokine levels. The balance of pro- and anti-inflammatory cytokines TNF/IL-10 and IL-6/IL-10 ratios were significantly higher in injected mice group when compared with those obtained for non-injected group. The CSV is poor in antigenic composition and it is difficult to get antibodies specific to neutralizing the lethal factor. The effect of immunization with 0.5 LD(50) of CSV on the balance of pro- and anti-inflammatory cytokines was measured. The maximum levels of TNF and IL-6, IFN-gamma and NO were observed on days 7 and 21 after immunization, respectively. IL-10 levels peaked between days 21 and 28 after immunization with CSV. With respect, to balance of pro- and anti-inflammatory cytokines it was possible to observe that negative correlation between serum levels of IL-6/IL-10 and TNF/IL-10 exists. These ratios may possibly reflect the balance of pro- and anti-inflammatory cytokines in serum, which may by manifested in the inflammatory status during the envenoming processes. In conclusion, an increase in the serum levels of TNF and IL-6 may be a useful marker for scorpion envenomation.     

Effect of a bifunctional monoclonal antibody directed against a tumor marker and doxorubicin on the growth of epidermoid vulvar carcinoma grafted in athymic mice

Even though the first monoclonal antibodies (MAbs) directed against tumor cells were produced 15 yr ago, the therapeutic application of immunoconjugates is still at the beginning. This is principally because of the enormous work that is required for the development of completely new therapeutic tools. An alternative could be to only use MAbs to improve conventional treatment such as chemotherapy. To this aim, a MAb directed against doxorubicin (DXR) was produced. DXR is an anthracycline antibiotic of which the clinical usefulness in cancer chemotherapy is limited by serious side effects, such as cardiomyopathy, bone marrow depression, and gastrointestinal tract mocositis. This toxicity was found to be reduced by treatment with the antidrug MAb, as shown by reduction in body weight loss and mortality of experimental mice. To improve the DXR therapeutic index, a bifunctional hybrid MAb (DOXER2), capable of simultaneously recognizing DXR and the epidermal growth factor (EGF) receptor, was produced. This reagent was found in vitro to increase the drug toxicity on the epidermoid carcinoma cell line A431, which overexpresses the EGF-R and, at the same time, to reduce DXR cytotoxicity on EGF-R negative cells. The effect of DOXER2 on the DXR biodistribution in vivo was also investigated. In mice previously injected ip with the DOXER2, the uptake of the drug, in comparison to the control group, was found to be reduced in the intestine and in myocardial tissue, and significantly increased in the tumor. The alteration in the drug distribution induced in mice by administration of the DOXER2 could prevent the drug from reaching critical toxic concentrations at sites such as the intestine and heart, which are the main targets of early anthracycline toxic effects. In conclusion, the data so far obtained show that this bifunctional MAb appears to be able to deliver the drug selectively to a tumor that overexpresses the EGF-R maintaining the capability to reduce DXR cytotoxicity on normal cells.     

A new dose-finding design for bivariate outcomes

For some drugs, toxicity events lead to early termination of treatment before a therapeutic response is observed. That is, there are three possible outcomes: toxicity (therapeutic response unknown), therapeutic response without toxicity, and no response with no toxicity. The optimal dose is the dose that maximizes the probability of the joint event, response, and no toxicity. The optimal safe dose is the dose, from among the doses with toxicity rate less than the maximum tolerable level, that maximizes the probability of response and no toxicity. We present a new sequential design to maximize the number of subjects assigned in the neighborhood of the optimal safe dose in a dose-finding trial with two outcomes.     

Controversial role of intracellular iron in the mechanisms of chemically-induced hepatotoxicity

Hepatotoxicity induced by various therapeutic agents, industrial chemicals and environmental pollutants is a well-recognized phenomenon. These chemicals are known to cause liver damage that is localized to either periportal or centrilobular regions of the liver lobule (1–3). Depending on dose, duration, and route of exposure, the resultant liver injury may regress or progress and becomes irreversible (1). Mechanisms involved in this selective, localized toxicity have been the target of extensive research efforts, and many Studies produced conflicting results. As depicted in Figure 1, although many investigators implicate iron and lipid peroxidation in this process (4-9), others dispute such assertions (10–12).     

Patient-specific dose finding based on bivariate outcomes and covariates

SUMMARY: A Bayesian sequential dose-finding procedure based on bivariate (efficacy, toxicity) outcomes that accounts for patient covariates and dose-covariate interactions is presented. Historical data are used to obtain an informative prior on covariate main effects, with uninformative priors assumed for all dose effect parameters. Elicited limits on the probabilities of efficacy and toxicity for each of a representative set of covariate vectors are used to construct bounding functions that determine the acceptability of each dose for each patient. Elicited outcome probability pairs that are equally desirable for a reference patient are used to define two different posterior criteria, either of which may be used to select an optimal covariate-specific dose for each patient. Because the dose selection criteria are covariate specific, different patients may receive different doses at the same point in the trial, and the set of eligible patients may change adaptively during the trial. The method is illustrated by a dose-finding trial in acute leukemia, including a simulation study.     

Pharmaceutical and pharmacological approaches for bioavailability enhancement of etoposide

Etoposide, a semi-synthetic derivative of podophyllotoxin, is one of the most active and useful antineoplastic agent used routinely in firstline combination chemotherapy of testicular cancer, small-cell lung cancer and non-Hodgkin’s lymphoma. Etoposide displays narrow therapeutic index, erratic pharmacokinetics and dose individualization that needs to be achieved for overcoming inter- and intra-patient variability (25–80%), so as to maintain proper drug exposure within a therapeutic range. Etoposide posses high plasma protein binding (97%) and is degraded via complex metabolic pathways. The main pharmacokinetic determinants of etoposide are still not completely defined in order to optimize the pharmaco-therapeutic parameters including dose, therapeutic schedule and route of administration. Much research has been done to determine drug–drug and herb–drug interactions for improving the bioavailability of etoposide. The present article gives insight on pharmaceutical and pharmacological attempts made from time to time to overcome the erratic inter- and intra-patient variability for improving the bioavailability of etoposide.     

Dose,timing, schedule,and the choice of targeted epitope alter the efficacy of anti-CD22 immunotherapy in mice bearing human lymphoma xenografts

CD22 is a cell-surface adhesion molecule on most B-cell NHL, so it is a promising target for immunotherapy. HB22.7 is an anti-CD22 mAb that binds the two NH₂-terminal immunoglobulin domains and specifically blocks the interaction of CD22 with its ligand. CD22-blocking mAbs induce apoptosis in neoplastic B-cells and are functionally distinguishable from other anti-CD22 mAbs. This study assessed the optimal dose, route, schedule, and the targeted CD22 epitope. Raji NHL-bearing nude mice were studied. A non-blocking anti-CD22 mAb (HB22.27) was used as a control. HB22.27 had minimal effect, whereas HB22.7 improved survival and shrank tumors substantially. HB22.7 doses greater than 1.4 mg/week did not further increase efficacy (or toxicity). Tumors less than 200 mm³ had a higher response rate than did larger tumors. Various schedules of HB22.7 administration were tested; one dose every other week was more effective than more or less frequent dosing. Pharmacokinetic studies revealed that the half-life of HB22.7 was 28 days; this correlated with the time needed to re-populate cell-surface CD22 after treatment with HB22.7. Immuno-PET showed that NHL was rapidly and specifically targeted by copper-64-labeled-HB22.7. This study provided data as to an optimal dose, route, schedule and interval between doses of HB22.7.     

Immunotherapy of solid cancer using dendritic cells pulsed with the HLA-A24-restricted peptide of carcinoembryonic antigen

Carcinoembryonic antigen (CEA), an oncofetal glycoprotein overexpressed in most gastrointestinal and lung cancers, is a candidate molecule for cancer immunotherapy. Recently, a CEA-derived 9-mer peptide, CEA652 (TYACFVSNL), has been identified as the epitope of cytotoxic T lymphocytes restricted with human leukocyte antigen (HLA)-A24, which is present in 60% of the Japanese population and in some Caucasians. The authors performed a clinical study of a vaccine using autologous dendritic cells (DCs) pulsed with CEA652 and adjuvant cytokines, natural human interferon alpha (nhuIFN-alpha), and natural human tumor necrosis factor alpha (nhuTNF-alpha), for the treatment of patients with CEA-expressing advanced metastatic malignancies. Ten HLA-A24 patients with advanced digestive tract or lung cancer were enrolled in the study to assess toxicity, tolerability and immune responses to the vaccine. DCs were generated from plastic adherent monocytes of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (PBMCs) in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4). Generated DCs showing an immature phenotype were loaded with CEA652 and injected into patients intradermally and subcutaneously with 50% of the dose administered by each route every 2 weeks for a total of ten vaccinations. The total dose of administered DCs ranged from 2.7x10(7)cells to 1.6x10(8)cells. Adjuvant cytokines, i.e., 1x10(6) U/body of nhuIFN-alpha and nhuTNF-alpha, were administered to patients twice a week during the vaccination period. No severe toxicity directly attributable to the treatment was observed, and the vaccine was well tolerated. In the delayed-type hypersensitivity (DTH) skin test, two patients showed a positive skin response to peptide-pulsed DCs after vaccination, although none of the patients tested positive prior to vaccination. In the two patients who showed a positive skin response disease remained stable for 6 and 9 months respectively. These results suggest that active immunization using DCs pulsed with CEA652 peptide in combination with the administration of adjuvant cytokines is a safe and feasible treatment procedure.     

Aerosol Azacytidine Inhibits Orthotopic Lung Cancers in Mice through Its DNA Demethylation and Gene Reactivation Effects

We devised an aerosol based demethylation therapy to achieve therapeutic efficacy in premalignant or in situ lesions of lung cancer, without systemic toxicity. Optimum regimens of aerosolized azacytidine (Aza) were designed and used in orthotopic human non-small cell lung cancer xenograft models. The therapeutic efficacy and toxicity of aerosol Aza were compared with intravenously administered Aza. We observed that 80% of the droplets of the aerosol Aza measured ∼0.1–5 microns, which resulted in deposition in the lower bronchial airways. An animal model that phenocopies field carcinogeneisis in humans was developed by intratracheal inoculation of the human lung cancer cells in mice, thus resulting in their distribution throughout the entire airway space. Aerosolized Aza significantly prolonged the survival of mice bearing endo-bronchial lung tumors. The aerosol treatment did not cause any detectable lung toxicity or systemic toxicity. A pre-pharmacokinetic study in mice demonstrated that lung deposition of aerosolized Aza was significantly higher than the intravenous route. Lung tumors were resected after aerosol treatment and the methylation levels of 24 promoters of tumor-suppresser genes related to lung cancer were analyzed. Aerosol Aza significantly reduced the methylation level in 9 of these promoters and reexpressed several genes tested. In conclusion, aerosol Aza at non-cytotoxic doses appears to be effective and results in DNA demethylation and tumor suppressor gene re-expression. The therapeutic index of aerosol Aza is >100-fold higher than that of intravenous Aza. These results provide a preclinical rationale for a phase I clinical trial of aerosol Aza to be initiated at our Institution.     

Hepatocyte growth factor enhances the clearance of a multidrug-resistant Mycobacterium tuberculosis strain by high doses of conventional chemotherapy,preserving liver function

Tuberculosis (TB) is one of the deadliest infectious diseases in humankind history. Although, drug sensible TB is slowly decreasing, at present the rise of TB cases produced by multidrug-resistant (MDR) and extensively drug-resistant strains is a big challenge. Thus, looking for new therapeutic options against these MDR strains is mandatory. In the present work, we studied, in BALB/c mice infected with MDR strain, the therapeutic effect of supra-pharmacological doses of the conventional primary antibiotics rifampicin and isoniazid (administrated by gavage or intratracheal routes), in combination with recombinant human hepatocyte growth factor (HGF). This high dose of antibiotics administered for 3 months, overcome the resistant threshold of the MDR strain producing a significant reduction of pulmonary bacillary loads but induced liver damage, which was totally prevented by the administration of HGF. To address the long-term efficiency of this combined treatment, groups of animals after 1 month of treatment termination were immunosuppressed by glucocorticoid administration and, after 1 month, mice were euthanized, and the bacillary load was determined in lungs. In comparison with animals treated only with a high dose of antibiotics, animals that received the combined treatment showed significantly lower bacterial burdens. Thus, treatment of MDR-TB with very high doses of primary antibiotics particularly administrated by aerial route can produce a very good therapeutic effect, and its hepatic toxicity can be prevented by the administration of HGF, becoming in a new treatment modality for MDR-TB.     

Th2/Th1 switch induced by a single low dose of cyclophosphamide in a rat metastatic lymphoma model

Cyclophosphamide (Cy) is an alkylating agent widely used in cancer chemotherapy. It has a bimodal effect on the immune system, depending on the dose and schedule of administration. We have previously demonstrated that a single low dose of Cy has an antimetastatic effect, achieved through immunomodulation, in lymphoma bearing rats. Such a treatment reduced the splenic production of IL-10, TGF-beta, and NO, restoring the lymphoproliferative capacity. A shift from immunosuppression to immunopotentiation induced by low-dose Cy treatment was mainly mediated by a decrease in IL-10 production. The present study focused on the analysis of the modulation of type-1 cytokine levels by treatment with a single low dose of Cy and the effect these cytokines (IL-2 and IFN-gamma) and IL-10 have on primary tumor and metastatic cell growth. Our results suggest that a single low dose of Cy induces a Th2/Th1 shift in the cytokine profile of lymphoma-bearing rats, which may be responsible for its antimetastatic effect. A direct action of IL-10 as a growth factor and IFN-gamma as a cytotoxic factor on metastatic cells is also shown.     

Serum IL-1beta,sIL-2R,IL-6, IL-8 and TNF-alpha in schizophrenic patients,relation with symptomatology and responsiveness to risperidone treatment.

Activation of the inflammatory response system and varied levels of cytokines in acute schizophrenia have been suggested by recent studies. Psychopharmacologic agents can differentially effect cytokine production, which suggests that therapeutic function of neuroleptics may involve immunomodulation. The present study was carried out to examine: (i) serum concentrations of interleukin (IL)-1beta, soluble interleukin-2 receptor (sIL-2R), IL-6, IL-8 and tumour necrosis factor (TNF)-alpha in schizophrenic patients; (ii) their relation with psychopathological assessment; and (iii) the relation of the initial cytokine levels with responsiveness to risperidone therapy. Thirty-four drug-free schizophrenic patients with acute exacerbation and 23 age- and gender-matched healthy controls were recruited for this study. Psychopathological assessments at admission and throughout risperidone treatment for 60 days were recorded. Serum cytokine concentrations were determined with chemilumunescence assays. According to our results, serum IL-1beta, sIL-2R, IL-6, IL-8 and TNF-alpha concentrations adjusted for age, gender, body mass index and smoking were no different in patients with schizophrenia and controls and among subtypes of schizophrenia. However, the initial TNF-alpha concentrations had a significant effect on Brief Psychiatric Rating Scale and Scale Assessment of Positive Symptoms scores. The initial cytokine concentrations of the patients responsive to risperidone were not significantly different from those of non-responsive patients. The present study demonstrates that plasma levels of IL-1beta, sIL-2R, IL-6, IL-8 and TNF-alpha adjusted for confounding factors are not altered in drug-free schizophrenic patients at acute exacerbation. We suggest that, if cytokine production is altered in schizophrenia, these alterations may not be detectable in systemic circulation. According to our results, the therapeutic effect of risperidone is not related to basal levels of the aforementioned cytokines. However, serum TNF-alpha may contribute to symptomatology in schizophrenia     

Cytokine regulation in RA synovial tissue: role of T cell/macrophage contact-dependent interactions

Several groups have documented the expression of cytokines in rheumatoid arthritis synovial tissue over the past 15 years or so. These studies have indicated that most cytokines examined are expressed at the mRNA levels at least, and many other cytokines are found in abundance as proteins. Our attention has recently focused on the mechanisms that induce and regulate tumour necrosis factor and IL-10. Other workers and ourselves have found that cell-cell contact is an important signal for the induction of cytokines, and our work has demonstrated that tumour necrosis factor and IL-10 production in rheumatoid arthritis synovial joint cells cultures is dependent on T cell/macrophage interaction. In this chapter, we review recent advances in this area and also highlight areas where new therapeutic intervention opportunities arise.     

Therapeutic myocardial angiogenesis with vascular endothelial growth factors

Emerging evidence has shown that administration of angiogenic growth factors, either as recombinant protein or by gene transfer, can augment tissue perfusion through neovascularization in animal models of myocardial and hindlimb ischemia. Many cytokines have angiogenic activity; one of those that have been best studied in animal models and clinical trials is vascular endothelial growth factor (VEGF). VEGF has been known to be a key regulator of physiologic and pathologic angiogenesis associated with tumor. Recently the effect of VEGF is not restricted to the direct angiogenic effect in vivo but includes mobilization of bone-marrow-derived endothelial progenitor cells and augmentation of postnatal vasculogenesis in situ. Clinical trials of therapeutic angiogenesis with VEGF in patients with end-stage coronary artery disease have shown increases in exercise time and reductions in anginal symptoms and have provided objective evidence of improved perfusion and left ventricular function. Larger scale placebo-controlled trials with recombinant protein (rhVEGF165) have been limited to intracoronary and intravenous administration and have shown favorable trends in exercise time and angina frequency. Small-scale, placebo-controlled, randomized clinical trials of gene transfer (phVEGF-2) via thoracotomy or percutaneous intramyocardial delivery demonstrated significant improvement of both subjective symptoms and objective measures of myocardial ischemia. Both therapeutic modalities appear to be safe and well tolerated. Further studies are required to determine the optimal dose, formulation, route of administration, and combinations of growth factors and the utility of adjunctive endothelial progenitor cell or other stem cell supplementation, to provide safe and effective therapeutic myocardial neovascularization.     

希罗达对4T1乳腺癌小鼠肿瘤血管生成的影响

目的:探讨不同剂量希罗达对4T1乳腺癌小鼠肿瘤血管生成的影响,并观察其抑瘤效果和毒副作用。方法:建立荷4T1乳腺癌小鼠模型,分别给予持续低剂量希罗达、最大耐受剂量(maximumtolerateddose,MTD)希罗达、低剂量希罗达治疗,观察肿瘤体积、小鼠体重和外周血白细胞计数及小鼠生存期。实验终末时行免疫组化染色,测定肿瘤微血管密度(MVD)和血管内皮生长因子(VEGF)表达情况。结果:与对照组和MTD希罗达治疗组比较,持续低剂量希罗达治疗组小鼠肿瘤MVD值和VEGF表达均显著降低(P<0.05)。与MTD希罗达治疗组比较,持续低剂量希罗达治疗组肿瘤生长比较缓慢,并且没有明显的体重减轻或白细胞数下降等毒性迹象,小鼠生存期无显著延长(P>0.05)。结论:持续低剂量希罗达给药方式靶向于乳腺癌血管生成,不易产生耐药,增加了抑瘤效果,毒副作用小,动物生存质量明显提高。