Challenges of Robust RNAi-Mediated Gene Silencing in Aedes Mosquitoes.

In this study, we report the complexities and challenges associated with achieving robust RNA interference (RNAi)-mediated gene knockdown in the mosquitoes Aedes aegypti and Aedes albopictus, a pivotal approach for genetic analysis and vector control. Despite RNAi's potential for species-specific gene targeting, our independent efforts to establish oral delivery of RNAi for identifying genes critical for mosquito development and fitness encountered significant challenges, failing to reproduce previously reported potent RNAi effects. We independently evaluated a range of RNAi-inducing molecules (siRNAs, shRNAs, and dsRNAs) and administration methods (oral delivery, immersion, and microinjection) in three different laboratories. We also tested various mosquito strains and utilized microorganisms for RNA delivery. Our results reveal a pronounced inconsistency in RNAi efficacy, characterized by minimal effects on larval survival and gene expression levels in most instances despite strong published effects for the tested targets. One or multiple factors, including RNase activity in the gut, the cellular internalization and processing of RNA molecules, and the systemic dissemination of the RNAi signal, could be involved in this variability, all of which are barely understood in mosquitoes. The challenges identified in this study highlight the necessity for additional research into the underlying mechanisms of mosquito RNAi to develop more robust RNAi-based methodologies. Our findings emphasize the intricacies of RNAi application in mosquitoes, which present a substantial barrier to its utilization in genetic control strategies.

Human skin long noncoding RNA WAKMAR1 regulates wound healing by enhancing keratinocyte migration.

An increasing number of studies reveal the importance of long noncoding RNAs (lncRNAs) in gene expression control underlying many physiological and pathological processes. However, their role in skin wound healing remains poorly understood. Our study focused on a skin-specific lncRNA, LOC105372576, whose expression was increased during physiological wound healing. In human nonhealing wounds, however, its level was significantly lower compared with normal wounds under reepithelialization. We characterized LOC105372576 as a nuclear-localized, RNAPII-transcribed, and polyadenylated lncRNA. In keratinocytes, its expression was induced by TGF-ß signaling. Knockdown of LOC105372576 and activation of its endogenous transcription, respectively, reduced and increased the motility of keratinocytes and reepithelialization of human ex vivo skin wounds. Therefore, LOC105372576 was termed "wound and keratinocyte migration-associated lncRNA 1" (WAKMAR1). Further study revealed that WAKMAR1 regulated a network of protein-coding genes important for cell migration, most of which were under the control of transcription factor E2F1. Mechanistically, WAKMAR1 enhanced E2F1 expression by interfering with E2F1 promoter methylation through the sequestration of DNA methyltransferases. Collectively, we have identified a lncRNA important for keratinocyte migration, whose deficiency may be involved in the pathogenesis of chronic wounds.

Validation of a coupled electromagnetic and thermal model for estimating temperatures during magnetic nanoparticle hyperthermia.

PURPOSE: Alternating magnetic field (AMF) tissue interaction models are generally not validated. Our aim was to develop and validate a coupled electromagnetic and thermal model for estimating temperatures in large organs during magnetic nanoparticle hyperthermia (MNH). MATERIALS AND METHODS: Coupled finite element electromagnetic and thermal model validation was performed by comparing the results to experimental data obtained from temperatures measured in homogeneous agar gel phantoms exposed to an AMF at fixed frequency (155 ± 10 kHz). The validated model was applied to a three-dimensional (3D) rabbit liver built from computed tomography (CT) images to investigate the contribution of nanoparticle heating and nonspecific eddy current heating as a function of AMF amplitude. RESULTS: Computed temperatures from the model were in excellent agreement with temperatures calculated using the analytical method (error < 1%) and temperatures measured in phantoms (maximum absolute error <2% at each probe location). The 3D rabbit liver model for a fixed concentration of 5 mg Fe/cm3 of tumor revealed a maximum temperature ∼44 °C in tumor and ∼40 °C in liver at AMF amplitude of ∼12 kA/m (peak). CONCLUSION: A validated coupled electromagnetic and thermal model was developed to estimate temperatures due to eddy current heating in homogeneous tissue phantoms. The validated model was successfully used to analyze temperature distribution in complex rabbit liver tumor geometry during MNH. In future, model validation should be extended to heterogeneous tissue phantoms, and include heat sink effects from major blood vessels.

Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia.

PURPOSE: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia. METHODS: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes' bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods. RESULTS: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating. CONCLUSIONS: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.

Increased uptake of doxorubicin by cells undergoing heat stress does not explain its synergistic cytotoxicity with hyperthermia.

Purpose: A proposed mechanism for the enhanced effectiveness of hyperthermia and doxorubicin (Dox) combinations is increased intracellular Dox concentrations resulting from heat-induced cell stress. The purpose of this study was to determine whether specific varied Dox and heat combinations produce measurable effects greater than the additive combination, and whether these effects can be attributed to heat-induced increases in intracellular Dox concentrations. Methods: HCT116, HT29 and CT26 cells were exposed to Dox and water bath heating independently. A clonogenic survival assay was used to determine cell killing and intracellular Dox concentrations were measured in HCT116 cells with mass spectrometry. Cells were exposed to heating at 42 °C (60 min) and 0.5 µg/ml of Dox at varying intervals. Synergy was determined by curve-fitting and isobologram analysis. Results: All cell lines displayed synergistic effects of combined heating and Dox. A maximum synergistic effect was achieved with simultaneous cell exposure to Dox and heat. For exposures at 42 °C, the synergistic effect was most pronounced at Dox concentrations <0.5 µg/ml. Increased intracellular concentrations of Dox in HCT116 cells caused by heat-stress did not generate a concomitant thermal enhancement. Conclusions: Simultaneous exposure of HCT116 cells to heating and Dox is more effective than sequential exposure. Heat-induced cell responses are accompanied by increased intracellular Dox concentrations; however, clonogenic survival data do not support this as the cause for synergistic cytotoxicity.

Successful liver-directed gene delivery by ERCP-guided hydrodynamic injection (with videos).

BACKGROUND AND AIMS: A simple, safe, targeted, and efficient in vivo DNA delivery system is necessary for clinical-grade liver-targeted gene therapy in humans. Intravascular hydrodynamic gene delivery has been investigated in large animal models, but translation to humans has been hampered by its technical challenges, invasiveness, and potential for significant cardiovascular adverse events. We posited that intrabiliary delivery of DNA plasmids via ERCP-guided hydrodynamic injection could overcome these obstacles. METHODS: Twelve pigs (40-50 kg) were divided into 3 groups (4 per group) and survived 21, 30, or 60 days. ERCP was performed by inflating a balloon catheter in the common hepatic duct and creating a closed space between it and the liver parenchyma. Last, a solution composed of plasmid/sleeping beauty (SB) mix was injected under pressure through the catheter into the closed space. Swine were killed at the 3 different time points and liver tissue harvested. Plasmid DNA expression and functional translated protein expression were assessed. RESULTS: ERCP-guided hydrodynamic delivery of naked plasmid DNA facilitated by pCytomegalovirus-Sleep Beauty (pCMV-SB) transposons was technically feasible and devoid of cardiovascular and local adverse events in all 12 pigs. Furthermore, plasmid DNA (both single and combination) was successfully transferred into swine hepatocytes in all 12 pigs. Additionally, stable integration of the DNA constructs in hepatocyte genomic DNA was reliably noted at all 3 time points. In the 4 swine that were kept alive to 60 days, successful genomic integration and subsequent protein expression was observed in the targeted liver tissue. CONCLUSIONS: ERCP-guided hydrodynamic delivery of gene therapy may usher in the next chapter in gene therapy with the potential to impact a variety of single-gene, complex genetic, and epigenetic liver diseases. It also raises the possibility that other nucleic acid therapeutics (microRNA, lncRNA, siRNA, shRNA) could similarly be delivered.

Evaluation of 70-150-µm doxorubicin-eluting beads for transcatheter arterial chemoembolization in the rabbit liver VX2 tumour model.

AIM: To evaluate the pharmacokinetic profile (PK) and embolization effect of 70-150-µm doxorubicin eluting beads (DEBs) following intra-arterial injection (i.a.) in the rabbit liver VX2 tumour model. MATERIALS AND METHODS: In this ACUC-approved study, 25 white New Zealand rabbits were randomly assigned into a small DEB group (SDB, n = 7, 70-150-µm DEBs), large DEB group (LDB, n = 7, 100-300-µm DEBs), untreated controls (n = 7), and doxorubicin controls (n = 4, without tumour, received i.a. 12.5 mg doxorubicin). Plasma PK was assessed up to 180 min post-injection. Drug tissue and liver enzyme levels, radiologic tumor response and histopathologic tumour necrosis were assessed at 7 days. RESULTS: Mean tumour doxorubicin concentrations were 922.83 nM (SD = 722.05) and 361.48 nM (SD = 473.23) for the SDB and LDB, respectively (p = 0.005). There was no statistically significant difference in tumour doxorubicinol, plasma doxorubicin and doxorubicinol PK values. More beads were observed in the SDB tumours (p = 0.01). Liver enzymes increased and gradually declined over the observation period, with significantly higher values in the SDB. CONCLUSION: In this preclinical study, plasma PK of i.a.-injected 70-150-µm DEBs was not different than that of 100-300-µm DEBs. More beads and higher tissue doxorubicin levels were observed in the SDB tumours. KEY POINTS: • Small and large doxorubicin-eluting beads show similar plasma pharmacokinetic profiles. • Higher tissue doxorubicin levels were observed in the small bead group. • Liver enzymes were overall significantly higher in the small bead group.

Image-guided thermal therapy with a dual-contrast magnetic nanoparticle formulation: A feasibility study.

PURPOSE/OBJECTIVE: The aim of this study was to develop and investigate the properties of a magnetic iron oxide nanoparticle-ethiodised oil formulation for image-guided thermal therapy of liver cancer. MATERIALS AND METHODS: The formulation comprises bionised nano-ferrite (BNF) nanoparticles suspended in ethiodised oil, emulsified with polysorbate 20 (BNF-lip). Nanoparticle size was measured via photon correlation spectroscopy and transmission electron microscopy. In vivo thermal therapy capability was tested in two groups of male Foxn1(nu) mice bearing subcutaneous HepG2 xenograft tumours. Group I (n = 12) was used to screen conditions for group II (n = 48). In group II, mice received one of BNF-lip (n = 18), BNF alone (n = 16), or PBS (n = 14), followed by alternating magnetic field (AMF) hyperthermia, with either varied duration (15 or 20 min) or amplitude (0, 16, 20, or 24 kA/m). Image-guided fluoroscopic intra-arterial injection of BNF-lip was tested in New Zealand white rabbits (n = 10), bearing liver VX2 tumours. The animals were subsequently imaged with CT and 3 T MRI, up to 7 days post-injection. The tumours were histopathologically evaluated for distribution of BNF-lip. RESULTS: The BNF showed larger aggregate diameters when suspended in BNF-lip, compared to clear solution. The BNF-lip formulation produced maximum tumour temperatures with AMF >20 kA/m and showed positive X-ray visibility and substantial shortening of T1 and T2 relaxation time, with sustained intratumoural retention up to 7 days post-injection. On pathology, intratumoural BNF-lip distribution correlated well with CT imaging of intratumoural BNF-lip distribution. CONCLUSION: The BNF-lip formulation has favourable thermal and dual imaging capabilities for image-guided thermal therapy of liver cancer, suggesting further exploration for clinical applications.

Intraprocedural C-arm dual-phase cone-beam CT: can it be used to predict short-term response to TACE with drug-eluting beads in patients with hepatocellular carcinoma?

PURPOSE: To investigate whether C-arm dual-phase cone-beam computed tomography (CT) performed during transcatheter arterial chemoembolization (TACE) with doxorubicin-eluting beads can help predict tumor response at 1-month follow-up in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: This prospective study was compliant with HIPAA and approved by the institutional review board and animal care and use committee. Analysis was performed retrospectively on 50 targeted HCC lesions in 29 patients (16 men, 13 women; mean age, 61.9 years ± 10.7) treated with TACE with drug-eluting beads. Magnetic resonance (MR) imaging was performed at baseline and 1 month after TACE. Dual-phase cone-beam CT was performed before and after TACE. Tumor enhancement at dual-phase cone-beam CT in early arterial and delayed venous phases was assessed retrospectively with blinding to MR findings. Tumor response at MR imaging was assessed according to European Association for the Study of the Liver (EASL) guidelines. Two patients were excluded from analysis because dual-phase cone-beam CT scans were not interpretable. Logistic regression models for correlated data were used to compare changes in tumor enhancement between modalities. The radiation dose with dual-phase cone-beam CT was measured in one pig. RESULTS: At 1-month MR imaging follow-up, complete and/or partial tumor response was seen in 74% and 76% of lesions in the arterial and venous phases, respectively. Paired t tests used to compare images obtained before and after TACE showed a significant reduction in tumor enhancement with both modalities (P < .0001). The decrease in tumor enhancement seen with dual-phase cone-beam CT after TACE showed a linear correlation with MR findings. Estimated correlation coefficients were excellent for first (R = 0.89) and second (R = 0.82) phases. A significant relationship between tumor enhancement at cone-beam CT after TACE and complete and/or partial tumor response at MR imaging was found for arterial (odds ratio, 0.95; 95% confidence interval [CI]: 0.91, 0.99; P = .023) and venous (odds ratio, 0.96; 95% CI: 0.93, 0.99; P = .035) phases with the multivariate logistic regression model. Radiation dose for two dual-phase cone-beam CT scans was 3.08 mSv. CONCLUSION: Intraprocedural C-arm dual-phase cone-beam CT can be used immediately after TACE with doxorubicin-eluting beads to predict HCC tumor response at 1-month MR imaging follow-up.

Intra-arterial therapy for advanced intrahepatic cholangiocarcinoma: a multi-institutional analysis.

BACKGROUND: Many patients with intrahepatic cholangiocarcinoma (ICC) present with advanced and inoperable disease. Data on the safety and efficacy of intra-arterial therapy (IAT) for ICC are limited. METHODS: Between 1992 and 2012, a total of 198 patients with advanced ICC treated with IAT were retrospectively identified from the databases of five major hepatobiliary institutions. Data on clinicopathological factors, morbidity, response rates, and overall survival were collected and analyzed. RESULTS: Median patient age was 61 years. Median tumor size was 8.1 cm, and 47.5% patients had a solitary lesion. IAT consisted of conventional transarterial chemoembolization (cTACE) (64.7%), drug-eluting beads (DEB) (5.6%), bland embolization (TAE) (6.6%), or yttrium-90 radioembolization (23.2%). Median number of IAT sessions was 2 (range 1-8). The median time between IAT sessions was 48 days. The periprocedural morbidity was 29.8%; most complications were minor (n = 43); however, 16 patients had a grade 3-4 complication. Assessment of tumor response revealed complete or partial response in 25.5% patients, while 61.5% had stable disease; 13.0% had progressive disease. Median overall survival was 13.2 months and did not differ on the basis of the type of IAT (cTACE, 13.4 months vs. DEB 10.5 months vs. TAE, 14.3 months vs. yttrium-90, 11.3 months; P = 0.46). IAT response on modified response evaluation criteria in solid tumors (mRECIST; hazard ratio for complete-partial response 0.49, 95% confidence interval 0.30-0.81; P < 0.001) was independently associated with better survival. CONCLUSIONS: IAT for ICC was safe and led to stable disease or partial to complete response in up to three-quarters of patients. Among patients with an IAT response, overall survival was prolonged. The role of IAT therapy for ICC warrants further prospective evaluation in clinical trials.

Image quality improvements in C-Arm CT (CACT) for liver oncology applications: preliminary study in rabbits.

INTRODUCTION: C-Arm CT (CACT) is a new imaging modality in liver oncology therapy that allows for the acquisition of 3D images intra-procedurally. CACT has been used to enhance intra-arterial therapies for the liver by improving lesion detection, avoiding non-target embolization, and allowing for more selective delivery of agents. However, one of the limitations of this technology is image artifacts created by respiratory motion. PURPOSE: To determine in this preliminary study improvements in image acquisition, motion compensation, and high resolution 3D reconstruction that can improve CACT image quality (IQ). MATERIAL AND METHODS: Three adult male New Zealand white rabbits were used for this study. First, a control rabbit was used to select the best x-ray acquisition imaging protocol and then two rabbits were implanted with liver tumor to further develop 3D image reconstruction and motion compensation algorithms. RESULTS: The best IQ was obtained using the low 80 kVp protocol with motion compensated reconstruction with high resolution and fast acquisition speed (60 fps, 5 s/scan, and 312 images). CONCLUSION: IQ improved by: (1) decreasing acquisition time, (2) applying motion-compensated reconstruction, and (3) high resolution 3D reconstruction. The findings of this study can be applied to future animal studies and eventually could be translated into the clinical environment.

Lack of response after initial chemoembolization for hepatocellular carcinoma: does it predict failure of subsequent treatment?

PURPOSE: To (a) evaluate the response of hepatocellular carcinoma (HCC) to chemoembolization after initial nonresponse, as determined with European Association for the Study of the Liver (EASL) criteria and modified Response Evaluation Criteria in Solid Tumors (mRECIST), and (b) compare posttreatment survival of initial nonresponders versus that of initial responders. MATERIALS AND METHODS: The institutional review board approved this retrospective study, which was compliant with HIPAA. A total of 116 consecutive patients (96 men, 20 women; mean age, 63 years) with unresectable HCC who underwent at least two chemoembolization procedures were included. The chemoembolization mixture consisted of 100 mg of cisplatin, 50 mg of doxorubicin, and 10 mg of mitomycin C mixed 1:1 with iodized oil. Tumor response at magnetic resonance imaging was evaluated after each chemoembolization procedure according to EASL criteria and mRECIST. The survival rate in each subgroup was calculated and correlated with response. The Wilcoxon test was used to test group comparability. Kaplan-Meier estimators were used to generate survival curves and compared by using the log-rank test. RESULTS: No response to initial chemoembolization was seen in 43% and 50% of patients according to EASL criteria and mRECIST, respectively. After a second chemoembolization procedure, 44% (EASL) and 47% (mRECIST) of initial nonresponders showed a significant response. With EASL criteria, the 1-, 2-, and 3-year survival rates (±standard error of the mean) after two chemoembolization procedures were 39%±10, 14%±7, and 0%, respectively, for nonresponders and 68%±10, 50%±11, and 37%±11 for responders (P=.036, P=.006, and P<.005 at 1, 2, and 3 years). With mRECIST, the 1-, 2-, and 3-year survival rates after two chemoembolization procedures were 49%±9, 20%±8, and 7%±6 for nonresponders and 67%±9, 44%±10, and 36%±9 for responders (P=.174, P=.046, and P=.011 at 1, 2, and 3 years). CONCLUSION: Patients who underwent chemoembolization for HCC showed a response (with both EASL criteria and mRECIST) and improved survival after the second chemoembolization treatment. At least two chemoembolization procedures should be performed in the same targeted lesions before further treatment is abandoned.

Systematic Review and Pharmacokinetic Meta-analysis of Doxorubicin Exposure in Transcatheter Arterial Chemoembolization and Doxorubicin-Eluted Beads Chemoembolization for Treatment of Unresectable Hepatocellular Carcinoma.

BACKGROUND: Almost 15 years after the introduction of transarterial chemoembolization (TACE) with drug-eluting beads (DEB-TACE) for hepatocellular carcinoma (HCC) therapy, the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) for doxorubicin have still not been systematically reviewed or meta-analyzed. OBJECTIVE: To conduct a systematic review and meta-analysis of available data and establish a reference range for Cmax and AUC of doxorubicin DEB-TACE and TACE, as well as explore the potential influence of microspheres' size and type on these parameters. METHODS: PubMed, EMBASE, and Web of Science were searched from August 1992 through December 2021. Studies measuring exposure parameters among HCC patients treated with doxorubicin DEB-TACE without restriction on language were included. Two independent reviewers extracted and unified data sets for pooled estimate analysis. The quality of the evidence was assessed via the Grading of Recommendations Assessment, Development and Evaluation framework. The ClinPK Statement checklist and Newcastle-Ottawa Scale (NOS) were used to determine the quality of studies. RESULTS: Out of 666 studies, 246 full-text were reviewed, and 8 studies entered the meta-analysis (120 patients). Cmax and AUC of doxorubicin were 7.52-fold (95% CI 7.65 to 7.42-fold; P < 0.0001) and 1.91-fold (95% CI 1.95 to 1.88-fold; P = 0.0001) lower with DEB-TACE compared to TACE. Significant reduction in pooled standardized mean difference (SMD) of Cmax and AUC was observed with DEB-TACE versus TACE in direct comparison analysis (- 2.93; 95% CI - 3.60 to - 2.26, P < 0.00001, and - 1.73 95% CI - 2.55 to - 0.91, P < 0.0001, respectively). Moreover, in DEB-TACE stratification analysis, small microspheres revealed higher Cmax, AUC and tumor response rate as well as lower complication rate. LIMITATION: The heterogeneity could not be completely addressed through sensitivity and stratification analysis. CONCLUSION: This meta-analysis provides exposure parameters of doxorubicin and justifies the advantage of DEB-TACE over TACE in terms of safety for patients with unresectable HCC. This study showed a marked association between the size of microsphere and exposure parameters of doxorubicin supporting the preference for small microspheres in DEB-TACE. The moderate and low quality of evidence is assigned to the Cmax and AUC, respectively.

Preliminary evaluation of alpha-emitting radioembolization in animal models of hepatocellular carcinoma.

Hepatocellular carcinoma is the most common primary liver cancer and the fifth most frequently diagnosed cancer worldwide. Most patients with advanced disease are offered non-surgical palliative treatment options. This work explores the first alpha-particle emitting radioembolization for the treatment and monitoring of hepatic tumors. Furthermore, this works demonstrates the first in vivo simultaneous multiple-radionuclide SPECT-images of the complex decay chain of an [225Ac]Ac-labeled agent using a clinical SPECT system to monitor the temporal distribution. A DOTA chelator was modified with a lipophilic moiety and radiolabeled with the α-particle emitter Actinium-225. The resulting agent, [225Ac]Ac-DOTA-TDA, was emulsified in ethiodized oil and evaluated in vivo in mouse model and the VX2 rabbit technical model of liver cancer. SPECT imaging was performed to monitor distribution of the TAT agent and the free daughters. The [225Ac]Ac-DOTA-TDA emulsion was shown to retain within the HEP2G tumors and VX2 tumor, with minimal uptake within normal tissue. In the mouse model, significant improvements in overall survival were observed. SPECT-imaging was able to distinguish between the Actinium-225 agent (Francium-221) and the loss of the longer lived daughter, Bismuth-213. An α-particle emitting TARE agent is capable of targeting liver tumors with minimal accumulation in normal tissue, providing a potential therapeutic agent for the treatment of hepatocellular carcinoma as well as a variety of hepatic tumors. In addition, SPECT-imaging presented here supports the further development of imaging methodology and protocols that can be incorporated into the clinic to monitor Actinium-225-labeled agents.

Neutrophil depletion enhanced the Clostridium novyi-NT therapy in mouse and rabbit tumor models.

BACKGROUND: Hypoxia is a prominent feature of solid tumors and can function as fertile environment for oncolytic anaerobic bacteria such as Clostridium novyi-NT (C. novyi-NT) where it can induce tumor destruction in mice and patients. However, two major obstacles have limited its use, namely the host inflammatory response and the incomplete clearance of normoxic tumor areas. METHODS: In this study, we first used a subcutaneous tumor model of a glioblastoma (GBM) cell line in immunocompetent mice to investigate the local distribution of tumor hypoxia, kinetics of C. novyi-NT germination and spread, and the local host immune response. We subsequently applied the acquired knowledge to develop a C. novyi-NT therapy in an orthotopic rabbit brain tumor model. RESULTS: We found that local accumulation of granular leukocytes, mainly neutrophils, could impede the spread of bacteria through the tumor and prevent complete oncolysis. Depletion of neutrophils via anti-Ly6G antibody or bone marrow suppression using hydroxyurea significantly improved tumor clearance. We then applied this approach to rabbits implanted with an aggressive intracranial brain tumor and achieved long-term survival in majority of the animals without apparent toxicity. CONCLUSION: These results indicated that depleting neutrophils can greatly enhance the safety and efficacy of C. novyi-NT cancer therapy for brain tumors.

Transcatheter intraarterial therapies: rationale and overview.

Transcatheter intraarterial therapies have proved valuable in the battle against primary and secondary hepatic malignancies. The unique aspects of all such therapies are their reduced toxicity profiles and highly effective tumor responses. These unique characteristics coupled with their minimally invasive nature provide an attractive therapeutic option in patients who may have previously had few alternatives. The concept of all catheter-based intraarterial therapies is to selectively deliver anticancer treatment to tumor(s). These therapies, which include transarterial embolization, intraarterial chemoinfusion, transarterial chemoembolization with or without drug-eluting beads, and radioembolization with use of yttrium 90, inflict lethal insult to tumors while preserving normal hepatic parenchyma. This is possible because hepatic neoplasms preferentially derive their blood supply from an arterial source while the majority of noncancerous liver is supplied by the portal vein. As part of the interventional oncology review series, in this article we describe the rationale behind each of these transcatheter therapies and provide a review of the existing medical literature.

Quantitative proton MR spectroscopy as a biomarker of tumor necrosis in the rabbit VX2 liver tumor.

PURPOSE: To compare metabolic magnetic resonance (MR) imaging findings (ie, quantification of tumor choline concentration) with percentage of necrosis on pathologic examination in rabbits bearing VX2 liver tumors. MATERIALS AND METHODS: VX2 tumors were implanted in the livers of 16 rabbits. MR imaging was performed with a 1.5-T MR scanner and extremity coil, and a hydrogen-1 ((1)H) proton MR spectroscopy ((1)H MRS) imaging protocol was used. Rabbits were euthanized immediately after imaging, and the tumor was harvested and sliced at 4-mm intervals in the axial plane. Choline concentration was calculated and was compared with the percentage of tumor necrosis on pathologic examination. RESULTS: Mean tumor size at pathologic examination was 16 mm (range, 12-22 mm). Mean percentage of necrosis at pathologic examination was 22% (range, 4%-44%). Choline concentration showed a relatively high inverse correlation with percentage of necrosis on pathologic examination, with an r value of 0.78 (P < .002). CONCLUSIONS: Choline concentration showed a relatively high inverse correlation with tumor necrosis on pathologic examination. Therefore, (1)H MRS may be useful to assess tumor necrosis.

Intra-arterial therapies for hepatocellular carcinoma: where do we stand?

PURPOSE AND DESIGN: Intra-arterial therapies for unresectable hepatocellular carcinoma (HCC) consist of a catheter-based group of treatments where therapeutic and/or embolic agents are intra-arterially directed to target tumors. Here we review these therapies, which may be classified into embolotherapy/chemotherapy-based and radiotherapy-based treatments. Embolotherapy/chemotherapy-based treatments include transcatheter arterial embolization, transarterial chemoembolization, transcatheter arterial chemoeinfusion, and chemoembolization with drug-eluting beads. Radiotherapy-based treatments include radioembolization with yttrium-90 and injection of iodine-131-labeled lipiodol. RESULTS AND CONCLUSION: Interpretation of the results of clinical trials as well as implementation of meta-analyses involving the efficacy of intra-arterial therapies for unresectable HCC has been challenging and difficult to perform. The levels of evidence for treatment recommendations in oncology provide a common framework to understand the current status of intra-arterial therapies for HCC. Here we use an evidence-based approach to critically review and comprehend the current role and future potential of intra-arterial therapies in unresectable HCC.

tRNAs and tRNA fragments as modulators of cardiac and skeletal muscle function.

Transfer RNAs (tRNAs) and their processing enzymes have long-recognized roles in cardiac and skeletal muscle pathophysiology. Recently, tRNA fragments have emerged as a new class of non-coding RNAs involved in the regulation of cell function. In this review, we provide a synopsis of the molecular processes that regulate the biogenesis, post-transcriptional regulation and functional roles of tRNAs in cardiac and skeletal muscle. In addition, we list the (dys)regulated expression profiles and putative functional roles of tRNA-derived small RNAs in the heart and skeletal muscle. Finally, the technical challenges surrounding tRNA research are discussed alongside suggestions to advance research in this field.

Combining Spectral CT Acquisition Methods for High-Sensitivity Material Decomposition.

Quantitative estimation of contrast agent concentration is made possible by spectral CT and material decomposition. There are several approaches to modulate the sensitivity of the imaging system to obtain the different spectral channels required for decomposition. Spectral CT technologies that enable this varied sensitivity include source kV-switching, dual-layer detectors, and source-side filtering (e.g., tiled spatial-spectral filters). In this work, we use an advanced physical model to simulate these three spectral CT strategies as well as hybrid acquisitions using all combinations of two or three strategies. We apply model-based material decomposition to a water-iodine phantom with iodine concentrations from 0.1 to 5.0 mg/mL. We present bias-noise plots for the different combinations of spectral techniques and show that combined approaches permit diversity in spectral sensitivity and improve low concentration imaging performance relative to the those strategies applied individually. Better ability to estimate low concentrations of contrast agent has the potential to reduce risks associated with contrast administration (by lowering dosage) or to extend imaging applications into targets with much lower uptake.