Rabbit VX2 Research Articles

Donafenib-Loaded Callispheres Beads Embolization in a VX2 Liver Tumor: Investigating Efficacy, Safety, and Improvement of Tumor Angiogenesis After Embolization.

ObjectiveTo investigate the efficiency and safety of callispheres beads loaded with donafenib (DCBs) for embolization in a VX2 liver tumor, as well as the improvement of tumor angiogenesis following embolization.MethodsForty New Zealand white rabbit VX2 liver tumors were treated with four different drugs via the hepatic artery: NS (normal saline), CB (blank callispheres beads), ACB (adriamycin-loaded callispheres beads) and DCB (DCBs). Hematoxylin-eosin staining was performed to assess tumor necrosis, while MRI was employed to detect the changes in tumor size. The safety was evaluated by the liver and kidney function parameters, and the immunofluorescence and immunohistochemical staining were performed to reflect the tumor hypoxia and tumor angiogenesis following embolization.ResultsThe DCB group had the smallest tumor growth rate, but the tumor necrosis rate was the highest of the four groups. Compared to the CB and ACB groups, the DCB group did not aggravate the liver damage and had no influence on kidney function. The staining results showed that, although the tumor hypoxia deteriorated after DCBs embolization, the expression of VEGF (vascular endothelial growth factor) reduced, thus inhibiting tumor angiogenesis.ConclusionDCB administration via hepatic artery is an effective and safe treatment for a preclinical liver cancer model, with the unique benefit of suppressing tumor angiogenesis following embolization.

Early Assessment of Response to Radiofrequency Ablation With CT Perfusion Imaging in Rabbit VX2 Liver Tumor Model.

ObjectivesTo discriminate viable tumors from benign periablational enhancement (BPE) in early stage after radiofrequency ablation (RFA) is a major confounding problem. The goal of this study is to evaluate quantitative assessment and diagnostic value of CT perfusion between viable tumors and BPE after RFA in the rabbit liver VX2 tumor model, with pathological results as the standard.MethodsTwenty-eight VX2 liver tumors were treated with RFA, on days 1, 3, 7, and 14, seven rabbits were randomly chosen for CT perfusion and performed pathology examinations immediately. The perfusion parameters along with the profile of time-density curves (TDCs) and pseudo-color images of the parameters were observed in both BPE and viable tumors, then compared with the pathology results. The perfusion parameters included blood flow (BF), blood volume (BV), time to peak (TTP), permeability (P), arterial liver perfusion (ALP), portal venous perfusion (PVP) and hepatic perfusion index (HPI).ResultsA total of 26/28 rabbits successfully underwent CT perfusion, while 6/26 lesions were confirmed to be viable tumors. The TDCs of BPE were mainly speed-up platform curves (15/26), while the viable tumors showed mainly speed-up speed-down (3/6) and speed-up platform (2/6) curves. The PVP values were significantly higher, and the HPI values were significantly lower for BPE at all time points than viable tumors (P < 0.05). Both of PVP value and HPI value have high efficiency for the differential diagnosis of the viable tumors and BPE at each time point. These characteristics of CT perfusion parameters were consistent with pathological changes.ConclusionsThe TDCs, PVP and HPI have the potential to indicate BPE and viable tumors effectively early after RFA treatment, the results were highly consistent with pathology. CT perfusion has advantages with great efficacy in monitoring the therapeutic effect early after RFA treatment.

Comparison of metabolic and immunologic responses to transarterial chemoembolization with different chemoembolic regimens in a rabbit VX2 liver tumor model.

The goal of this study was to investigate the effects of TACE using Lipiodol, Oncozene™ drug-eluting embolics (DEEs), or LUMI™-DEEs alone, or combined with bicarbonate on the metabolic and immunological tumor microenvironment in a rabbit VX2 tumor model. VX2 liver tumor-bearing rabbits were assigned to five groups. MRI and extracellular pH (pHe) mapping using Biosensor Imaging of Redundant Deviation in Shifts (BIRDS) were performed before and after intra-arterial therapy with conventional TACE (cTACE), DEE-TACE with Idarubicin-eluting Oncozene™-DEEs, or Doxorubicin-eluting LUMI™-DEEs, each with or without prior bicarbonate infusion, and in untreated rabbits or treated with intra-arterial bicarbonate only. Imaging results were validated with immunohistochemistry (IHC) staining of cell viability (PCNA, TUNEL) and immune response (HLA-DR, CD3). Statistical analysis was performed using Mann-Whitney U test. pHe mapping revealed that combining cTACE with prior bicarbonate infusion significantly increased tumor pHe compared to control (p = 0.0175) and cTACE alone (p = 0.0025). IHC staining revealed peritumoral accumulation of HLA-DR+ antigen-presenting cells and CD3 + T-lymphocytes in controls. cTACE-treated tumors showed reduced immune infiltration, which was restored through combination with bicarbonate. DEE-TACE with Oncozene™-DEEs induced moderate intratumoral and marked peritumoral infiltration, which was slightly reduced with bicarbonate. Addition of bicarbonate prior to LUMI™-beads enhanced peritumoral immune cell infiltration compared to LUMI™-beads alone and resulted in the strongest intratumoral immune cell infiltration across all treated groups. The choice of chemoembolic regimen for TACE strongly affects post-treatment TME pHe and the ability of immune cells to accumulate and infiltrate the tumor tissue. • Combining conventional transarterial chemotherapy with prior bicarbonate infusion increases the pHe towards a more physiological value (p = 0.0025). • Peritumoral infiltration and intratumoral accumulation patterns of antigen-presenting cells and T-lymphocytes after transarterial chemotherapy were dependent on the choice of the chemoembolic regimen. • Combination of intra-arterial treatment with Doxorubicin-eluting LUMI™-beads and bicarbonate infusion resulted in the strongest intratumoral presence of immune cells (positivity index of 0.47 for HLADR+-cells and 0.62 for CD3+-cells).

Yttrium-90 Radioembolization in the VX2 Rabbit Model: Radiation Safety and Factors Influencing Delivery Efficiency

The purpose of this study was to define the optimal infusion parameters and operator radiation exposure for yttrium-90 (90Y) radioembolization in the VX2 rabbit model of liver cancer. Forty-one rabbits with VX2 were treated with glass microspheres with vial sizes of 1, 3, and 5 GBq. The mean administered activity was 51.5 MBq (95% CI, 39.1–63.9). Delivery efficiency improved with 1 GBq versus with 3 GBq (residual 11.0% vs 46.4%, respectively; P = .0013) and improved with 1 GBq versus with 5 GBq (residual 11.0% vs 33.8%, respectively; P = .0060). The mean operator extremity exposure was 41.7 μSv/infusion. The optimal minimum infusion volume and rate was 49 mL and 21 mL/min, respectively. Fecal elimination occurred with microsphere uptake in the gallbladder at 1 and 2 weeks. 90Y radioembolization can be safely and efficiently performed in the VX2 rabbit model. Methodological considerations as a “how-to” for the setup of a preclinical 90Y laboratory are included to support future translational research.

Noninvasive evaluation of hypoxia in rabbit VX2 lung transplant tumors using spectral CT parameters and texture analysis.

Noninvasive evaluation of hypoxia in rabbit VX2 lung transplant tumors using spectral CT parameters and texture analysis. Twenty-five VX2 lung transplant tumors of twenty-two rabbits were included in the study. Contrast-enhanced spectral CT scanning in the arterial phase (AP) and venous phase (VP) was performed. Tumors were divided into strong and weak hypoxic groups by hypoxic probe staining results. Spectral CT image-related parameters [70keV CT value, normalized iodine concentration (NIC), slope of spectral HU curve (λHU)] were measured and the texture analysis on the monochromatic images was performed. Imaging parameters and texture features between tumors with different hypoxic degrees were compared and their diagnostic efficacies for predicting hypoxia in lung cancers were analyzed using receiver operating characteristic (ROC) curve. NIC in VP and λHU in VP of the strong hypoxic group were significantly higher than those in the weak hypoxic group (p < 0.05). For the texture features, entropy in VP and kurtosis in AP were significantly different between the two hypoxic groups. According to ROC analysis, λHU in VP had a better diagnostic ability for predicting hypoxia in tumors [Area Under Curve (AUC): 0.883, sensitivity: 85.7%, specificity: 100%]. The combination of four features improved AUC to 0.955. NIC in VP, λHU in VP, entropy in VP and kurtosis in AP have certain values in predicting tumor hypoxia and a combination of image parameters and texture features improves diagnostic efficiency.

Intraarterial Lidocaine Administration for Pain Control by Water-in-Oil Technique in Transarterial Chemoembolization: in vivo and Randomized Clinical Trial.

ObjectiveTo investigate the sustained release of lidocaine from a lidocaine–epirubicin–lipiodol emulsion created by water-in-oil (W/O) technique in vivo and evaluate the efficacy and safety of intraarterial lidocaine administration for intra- and postoperative pain control in transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC).MethodsThe in vivo concentrations of lidocaine were determined in tumor tissues after VX2 rabbit models for hepatic tumor were administered with intra-arterial lidocaine–epirubicin–lipiodol emulsion. A prospective randomized controlled clinical trial was performed, enrolling 70 consecutive patients who underwent TACE. Patients were randomized into two groups: Group A received an immediate bolus intraarterial lidocaine injection before TACE, and Group B received a lidocaine–epirubicin–lipiodol emulsion during TACE. Pain intensity was compared between the two groups using a visual analog scale (VAS) score before (Tbefore) and at 0 h (T0), 4 h (T4), 8 h (T8), 24 h (T24), 48 h (T48), and 72 h (T72) after the procedure. Adverse events and intake of analgesics were evaluated and compared between the two groups.ResultsThe concentrations of lidocaine in tumor tissues were higher in experimental group than in control group at T0.5 (P=0.004), T1 (P=0.038), T4 (P=0.036), and T8 (P=0.029). In the clinical trial, VAS scores in Group B were significantly lower than in Group A at T0 (P=0.006), T4 (P=0.001), T8 (P=0.002), and T24 (P=0.005). The tramadol intake in Group B was significantly lower than in Group A (P=0.021). No significant difference was observed regarding the incidence of adverse events between the two groups.ConclusionThis study demonstrated the effectiveness and safety of intraarterial lidocaine administration using the W/O technique in controlling intra- and post-TACE pain.

Monitoring the therapeutic efficacy of CA4P in the rabbit VX2 liver tumor using dynamic contrast-enhanced MRI.

The present work aims to evaluate whether dynamic contrast-enhanced magnetic resonance Imaging (DCE-MRI) can monitor non-invasively the blocking effect on microvessels of the Combretastatin-A4-phosphate (CA4P) and assess the therapeutic efficacy. Forty rabbits were implanted the VX2 tumors specimens. Two weeks later, serial MRI (T1 weighted image, T2 weighted image and DCE) were performed at 0 h, 4 h, 24 h, 3 d and 7 d after CA4P (10 mg/kg) or saline treatment. The parameters of DCE (Ktrans, Kep, Ve and iAUC60) of enhancement tumor portions were measured. Then all the tumor samples were stained to count microvessel density (MVD). At last, two-way repeated measures ANOVA was used to analyze the difference between and within groups. The correlation between the Ktrans, Kep, Ve, iAUC60 and MVD was analyzed by using the Pearson correlation analysis and Spearman's rank correlation. The Ktrans and iAUC60 in the CA4P group were lower than the values of the control group at 4 h after treatment, which have significant differences (D-value: -0.133 min-1, 95%CI: -0.169~-0.097 min-1，F = 59.109, p < 0.001 for Ktrans; D-value: -10.533 mmol/sec, 95%CI: -17.147~-3.919 mmol/sec，F = 11.110, and p = 0.003 for iAUC60). In the CA4P group, the Ktrans and iAUC60 reached the minimum values at 4 h. There were significant differences between 4 h and other different time points of the Ktrans and iAUC60 in the treatment group (all p < 0.01). The parameters Ktrans (r = 0.532, P = 0.016 and r = 0.681, P = 0.001, respectively) and iAUC60 (r = 0.580, P = 0.007 and r = 0.568, P = 0.009, respectively) of 7 days showed correlation with MVD in both groups, while Kep and Ve did not show correlation with MVD (P > 0.05). The blocking effect of microvessels after CA4P treatment can be evaluated by DCE-MRI, and the parameters of quantitative Ktrans and semi- quantitative iAUC60 can assess the change of the tumor angiogenesis noninvasively.

Transcatheter Arterial Embolization Containing Donafenib Induces Anti-Angiogenesis and Tumoricidal CD8+ T-Cell Infiltration in Rabbit VX2 Liver Tumor

PurposeTo evaluate the effect and immune response of transcatheter arterial embolization (TAE) combined with donafenib in rabbit VX2 liver tumor model.Materials and MethodsThirty-six New Zealand white rabbits with VX2 liver tumor were randomly divided into three groups. The LD group was treated with the emulsion of 0.5 mL lipiodol and 4 mg donafenib via hepatic arterial administration. The LE group was treated with the emulsion of 0.5 mL lipiodol and 4 mg epirubicin. The control group was treated with the equal volume of saline. Four rabbits were euthanized in each group on day 1, 3 and 7 after treatment. The tumor growth, histological markers associated with angiogenesis and immune response were assessed by imaging and histopathology. In addition, immune modulatory cytokines included interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and biochemical hepatorenal function were measured.ResultsCompared to other groups, LD group achieved lower tumor growth rate, fewer metastatic lesions, and higher tumor necrosis rate on day 7 after treatment. The percentage of CD31-positive area in the LD group was significantly lower than that in the LE group on day 3 and 7 after treatment. In addition, CD8+ lymphocytes infiltration was more pronounced in LD group than in LE group on day 7 after treatment, regardless of in the tumor or adjacent liver tissue. Serum cytokines including IL-6, TNF-α and IFN-γ were strongly upregulated in the LD group on day 1 after treatment. And there was no significant difference in the hepatorenal function between LD group and LE group after treatment.ConclusionThe combination of TAE and angiogenesis inhibitor donafenib resulted in a potentiated tumoricidal effect, anti-angiogenesis and antitumour T cell response in rabbit VX2 liver tumor model. This may provide a potential basis for exploring the immune-related mechanisms of embolization in liver cancer.

The diagnostic efficiency of the perfusion-related parameters in assessing the vascular disrupting agent (CA4P) response in a rabbit VX2 liver tumor model.

There are inconsistencies when concomitantly using dynamic contrast enhancement (DCE) and intravoxel incoherent motion (IVIM) to evaluate diagnostic efficiency. To evaluate the diagnostic efficiency of perfusion-related parameters in assessing the effect of Combretastatin-A4-phosphate (CA4P) in a rabbit VX2 liver tumor model using DCE and IVIM. Twenty rabbits implanted with VX2 tumors were included in the study. The perfusion-parameters of DCE (Ktrans and iAUC60) and IVIM (f and D*) were measured at baseline and 4 h after administration of CA4P. Subsequently, the rabbits were euthanized. Pre- and post-treatment perfusion parameters were analyzed using paired t-test. Correlation between the various perfusion parameters and correlation of perfusion parameters with microvascular density (MVD) were assessed using Pearson correlation analysis. The diagnostic efficiency was evaluated using receiver operating characteristic (ROC) curve analysis. All perfusion parameters (Ktrans, iAUC60, f and D*) showed significant decrease after 4 h of CA4P administration (all P < 0.001). Post-treatment perfusion parameters showed a moderate correlation with MVD (r = 0.663, r = 0.567, r = 0.685, r = 0.618, respectively; all P < 0.05). At baseline and after treatment, Ktrans values and iAUC60 showed correlation with f and D* (all P < 0.05). Concomitant use of perfusion parameters of DCE and IVIM showed the best diagnostic performance, which was slightly greater than that observed with individual application of DCE or IVIM (AUC = 0.915, 0.880, and 0.895, respectively). Although concomitant application of DCE and IVIM can slightly improve the diagnostic value in assessing the effect of CA4P, the values were relatively small.

Effect of diagnostic ultrasound and microbubble-enhanced chemotherapy on metastasis of rabbit VX2 tumor.

Ultrasound-targeted microbubble destruction (UTMD) has been widely applied to enhance chemotherapy of tumors, yet few studies have focused on the metastatic potential induced by UTMD. This study aimed to explore the metastasis of VX2 tumors after treatment with UTMD and chemotherapy. Forty-four New Zealand rabbits bearing subcutaneous VX2 tumors were enrolled for the treatment of UTMD with chemotherapy. For UTMD, the tumors were insonated using two pulsing protocols of diagnostic ultrasound (DUS, VINNO and ECARE) with a mechanical index (MI) of 0.29-0.33, tone burst of 8.0 cycles, and frequencies of 3-4MHz. A total dose of 2ml SonoVue® was injected intermittently during 10-min UTMD exposure. The combination therapy was treated using doxorubicin (DOX, 2mg/kg) and DUS, while the tumors treated using DOX only served as the control. Tumor size was measured using the tumor volume formula. Survival time was observed until animal death or the end of the study (120days). Specific organs (lung, liver, kidney, and brain) were removed for metastatic evaluation. There were no statistical differences in overall metastasis classification and individual organ metastases among all groups (P>0.05). The tumor growth rate only showed inhibition on the 5th day (P<0.01). The survival time did not demonstrate any significant difference between UTMD and chemotherapy only (P>0.05). UTMD using long-pulse DUS with commercial microbubbles did not pose a risk of metastasis enhancement in DOX chemotherapy.

Development of a 3D-Printed Navigational Template for Establishing Rabbit VX2 Lung Cancer Model

The CT-guided percutaneous puncture-inoculation for establishing the rabbit VX2 lung cancer model (LCM) is time-consuming, requires repeated CT scans, and has a high complication rate. Therefore, this study aimed to develop a navigational template using 3D technology to provide an alternative method for establishing the model with improved success and complication rates. Ideal pressure was determined using chest CT data from 15 anesthetized rabbits fitted with sphygmomanometer cuff around their chests. Subsequently, a preliminary 3D template with a square window and cross-sign to facilitate precise installation was designed. Using another 20 rabbits fixed with the preliminary template, an ideal common puncture point and parameter were determined, a navigational tunnel was set up on the template surface, and the final puncture navigational template was printed out. Eight-four rabbits (42/group) were assigned to the experimental (template-guided puncture) and control (traditional puncutre) groups and underwent VX2 tumor-fragment inoculation to validate the template. Differences in various parameters between two groups were analyzed. The ideal pressure was 30 mmHg. All rabbits were inoculated successfully and the template adequately fit the rabbit chest. The experimental group displayed significantly better operation time (198.93±36.64 vs 735.14±91.19 seconds); number of CT scans (0 vs 7.19±1.64); pneumothorax (11.9% vs 35.7%), chest seeding (16.7% vs 35.7%), and mid-lung field tumor-bearing (88.1% vs 59.5%) rates than the control group (all, P <0.05). The groups did not differ in rib injury, tumor volume or survival time (all, P > 0.05). We successfully developed a puncture navigational template, providing an alternative method for establishing the rabbit VX2 LCM.

Magnetic mesoporous embolic microspheres in transcatheter arterial chemoembolization for liver cancer

Transcatheter arterial chemoembolization (TACE) is the main treatment for liver cancer. Although many embolic agents have been exploited in TACE, embolic agents combining embolization, drug loading, and imaging properties have not yet been constructed. Herein, we report a new magnetic mesoporous embolic microsphere that can simultaneously be loaded with doxorubicin (Dox), block vessels, and be observed by magnetic resonance imaging (MRI). The microspheres were prepared by decorating magnetic polystyrene/Fe3O4 particles with mesoporous organosilica microparticles (denoted as PS/Fe3O4@MONs). The PS/Fe3O4@MONs were uniformly spherical and large (50 µm), with a high specific surface area, uniform mesopores, and a Dox loading capacity of 460.8 µg mg−1. Dox-loaded PS/Fe3O4@MONs (PS/Fe3O4@MON@Dox) effectively inhibited liver cancer cell growth. A VX2 rabbit liver tumor model was constructed to study the efficacy of TACE with PS/Fe3O4@MON@Dox. In vivo, PS/Fe3O4@MON@Dox could be smoothly delivered through an arterial catheter to achieve chemoembolization. Moreover, PS/Fe3O4@MON@Dox and residual tumor parenchyma could be distinguished on MRI, which is of great significance for evaluating the efficacy of TACE. Histopathology showed that PS/Fe3O4@MON@Dox could be deposited in the tumor vessels, completely blocking the blood supply. Overall, PS/Fe3O4@MON@Dox showed good drug loading, embolization and imaging performance as well as potential for use in TACE. Statement of SignificanceTranscatheter arterial chemoembolization (TACE) is the main treatment for liver cancer. Although many embolic agents have been exploited in TACE, embolic agents combining embolization, drug-loading, and imaging properties have not yet been constructed. In this work, we prepared magnetic mesoporous microspheres as a new embolic agent that can simultaneously load doxorubicin (Dox), block blood vessels and enable magnetic resonance imaging. Overall, this new embolic microsphere-mediated TACE strategy for liver cancer showed good therapeutic effects, and the PS/Fe3O4@MON@Dox embolic microspheres provide a new avenue for improving the efficacy of TACE for liver cancer and postoperative evaluation.

Establishment of a modified percutaneous CT-guided paraspinal intramuscular VX-2 squamous cell carcinoma dual tumor model in rabbits.

BackgroundThe rabbit VX-2 tumor model is a commonly used transplanted tumor model and is widely used in surgical, radiological, and interventional studies. Most of the known tumor models for each site are single solid tumors. This study aimed to establish an accurate and stable intramuscular dual tumor model guided by computed tomography (CT).MethodsIn this study, we compared three different inoculation methods to select the most appropriate dual tumor model. Six New Zealand White rabbits were used as tumor-carrying rabbits for tumor harvesting. Thirty rabbits were divided into three groups as experimental rabbits. Group A applied the tumor cell suspension method, in which the suspension was injected into the designated location with a syringe under CT guidance. Groups B and C used tumor tissue strips obtained in vivo or under direct in vitro vision. The tumor tissue strips were implanted into the designated locations using a guide needle under CT guidance. The differences in tumorigenic rate, the size difference between bilateral tumors, and metastasis between the three methods were compared.ResultsIt was found that group A obtained a 100% tumor survival rate, but the size of the tumor was more variable, and needle tract implantation metastasis occurred in 5 cases. In group B, tumor tissue strips were taken in vivo for implantation, in which one case failed to survive. Tumor tissue strips in group C were obtained in vitro under direct vision. The tumor tissue strips obtained in vitro by puncture using a biopsy needle in group C had a 100% tumorigenicity rate and stable tumor size. No significant needle tract implantation metastases were found in either group B or C. The variance of tumor size obtained in group A was significantly higher than in groups B and C. The variance of tumor size in group C was the smallest. Group C had high tumorigenicity and a more stable size and morphology of the formed tumors.ConclusionThe results showed that the method of obtaining tumor tissue strips using in vitro direct vision puncture and implanting them into the muscle with CT guidance and guide needles can establish an accurate and stable dual tumor model. This dual tumor model can provide substantial support for relevant preclinical studies.

Differentiation of microinfiltration and simple-edema areas in VX2 bone tumors by diffusion kurtosis imaging in animal experiments: a preliminary study.

Dual-energy computed tomography, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can be used to distinguish microinvasion areas of malignant bone tumors. However, reports of diffusion kurtosis imaging (DKI) to determine the extent of intramedullary infiltration are relatively rare. To assess the application value of MR-DKI in differentiating areas of microinfiltration and simple edema in rabbit bone VX2 tumor models. Conventional MRI and DKI were performed on 25 successfully constructed rabbit VX2 bone tumor models. We acquired a midline sagittal section of the tumor for hematoxylin and eosin staining. Using pathological findings as the gold standard and combining them with MRI data, strict point-to-point control was performed to delineate regions of interest (ROIs) in the microinfiltration and simple-edema areas of bone tumors for quantitative measurement of mean diffusivity (MD) and mean kurtosis (MK). MD and MK values between microinfiltration and simple-edema areas were compared using an independent sample t-test, and the diagnostic values were evaluated by receiver operating characteristic (ROC) curve analysis. In comparison with the simple-edema area, the micro-infiltration area demonstrated significantly smaller MD values and larger MK values (P < 0.05), and MD showed a better area under the curve (AUC) than MK (AUC = 0.884 vs. AUC = 0.690) for distinguishing the microinfiltration area from the simple-edema area. The optimal cutoff MD value was 1108.5 mm2/s with a sensitivity of 84% and specificity of 84%. DKI can distinguish the microinfiltration and simple-edema areas of malignant bone tumors in animal experiments.

Reduction of microwave ablation needle related metallic artifacts using virtual monoenergetic images from dual-layer detector spectral CT in a rabbit model with VX2 tumor

The purpose of the study was to investigate the application of virtual monoenergetic images (VMIs) in reducing metal artifacts in rabbit VX2 liver cancer models treated with microwave ablation (MWA) therapy. A total of 31 VX2 liver cancer models that accepted CT-guided percutaneous microwave ablation were analyzed. Conventional images (CIs) with the most severe metallic artifacts and their corresponding energy levels from 40 to 200 keV with 10 keV increment of VMIs were reconstructed for further analysis. Objective image analysis was assessed by recording the attenuation (HU) and standard deviation of the most severe hyper/hypodense artifacts as well as artifact-impaired liver parenchyma tissue. Two radiologists visually evaluated the extent of artifact reduction, assessed data obtained by a diagnostic evaluation of liver tissues, and appraised the appearance of new artifacts according to the grade score. Statistical analysis was performed to compare the difference between CIs and each energy level of VMIs. For subjective assessment, reductions in hyperdense and hypodense artifacts were observed at 170–200 keV and 160–200 keV, respectively. The outcomes of the diagnostic evaluation of adjacent liver tissue were statistically higher at 140–200 keV for VMIs than for CIs. In terms of objective evaluation results, VMIs at 90–200 keV reduced the corrected attenuation of hyperdense and of artifact-impaired liver parenchyma compared with CIs (P < 0.001). When VMIs at 80–200 keV decreased the hypodense artifacts (P < 0.001). Therefore, we concluded that VMIs at 170–200 keV can obviously decrease the microwave ablation needle-related metal artifacts objectively and subjectively in rabbit VX2 liver cancer models.

Conventional versus drug-eluting embolic transarterial chemoembolization with doxorubicin: comparative drug delivery, pharmacokinetics, and treatment response in a rabbit VX2 tumor model.

The purpose of this study was to compare intra-tumoral drug delivery, pharmacokinetics, and treatment response after doxorubicin (DOX) conventional (c-) versus drug-eluting embolic (DEE-) transarterial chemoembolization (TACE) in a rabbit VX2 liver tumor model. Twenty-four rabbits with solitary liver tumors underwent c-TACE (n=12) (1:2 water-in-oil emulsion, 0.6mL volume, 2mg DOX) or DEE-TACE (n=12) (130,000 70-150µm 2mg DOX-loaded microspheres). Systemic, intra-tumoral, and liver DOX levels were measured using mass spectrometry up to 7-day post-procedure. Intra-tumoral DOX distribution was quantified using fluorescence imaging. Percent tumor necrosis was quantified by a pathologist blinded to treatment group. Lobar TACE was successfully performed in all cases. Peak concentration (CMAX, µg/mL) for plasma, tumor tissue, and liver were 0.666, 4.232, and 0.270 for c-TACE versus 0.103, 8.988, and 0.610 for DEE-TACE. Area under the concentration versus time curve (AUC, µg/mL ∗ min) for plasma, tumor tissue, and liver were 18.3, 27,078.8, and 1339.1 for c-TACE versus 16.4, 26,204.8, and 1969.6 for DEE-TACE. A single dose of intra-tumoral DOX maintained cytotoxic levels through 7-day post-procedure for both TACE varieties, with a half-life of 1.8 (c-TACE) and 0.8 (DEE-TACE) days. Tumor-to-normal liver DOX ratio was high (c-TACE, 20.2; DEE-TACE, 13.3). c-TACE achieved significantly higher DOX coverage of tumor vs. DEE-TACE (10.8% vs. 2.3%; P=0.003). Percent tumor necrosis was similar (39% vs. 37%; P=0.806). In conclusion, in a rabbit VX2 liver tumor model, both c-TACE and DEE-TACE achieved tumoricidal intra-tumoral DOX levels and high tumor-to-normal liver drug ratios, though c-TACE resulted in significantly greater tumor coverage.

Elastin-specific MRI of extracellular matrix-remodelling following hepatic radiofrequency-ablation in a VX2 liver tumor model

Hepatic radiofrequency ablation (RFA) induces a drastic alteration of the biomechanical environment in the peritumoral liver tissue. The resulting increase in matrix stiffness has been shown to significantly influence carcinogenesis and cancer progression after focal RF ablation. To investigate the potential of an elastin-specific MR agent (ESMA) for the assessment of extracellular matrix (ECM) remodeling in the periablational rim following RFA in a VX2 rabbit liver tumor-model, twelve New-Zealand-White-rabbits were implanted in the left liver lobe with VX2 tumor chunks from donor animals. RFA of tumors was performed using a perfused RF needle-applicator with a mean tip temperature of 70 °C. Animals were randomized into four groups for MR imaging and scanned at four different time points following RFA (week 0 [baseline], week 1, week 2 and week 3 after RFA), followed by sacrifice and histopathological analysis. ESMA-enhanced MR imaging was used to assess ECM remodeling. Gadobutrol was used as a third-space control agent. Molecular MR imaging using an elastin-specific probe demonstrated a progressive increase in contrast-to-noise ratio (CNR) (week 3: ESMA: 28.1 ± 6.0; gadobutrol: 3.5 ± 2.0), enabling non-invasive imaging of the peritumoral zone with high spatial-resolution, and accurate assessment of elastin deposition in the periablational rim. In vivo CNR correlated with ex vivo histomorphometry (ElasticaVanGiesson-stain, y = 1.2x − 1.8, R2 = 0.89, p < 0.05) and gadolinium concentrations at inductively coupled mass spectroscopy (ICP-MS, y = 0.04x + 1.2, R2 = 0.95, p < 0.05). Laser-ICP-MS confirmed colocalization of elastin-specific probe with elastic fibers. Following thermal ablation, molecular imaging using an elastin-specific MR probe is feasible and provides a quantifiable biomarker for the assessment of the ablation-induced remodeling of the ECM in the periablational rim.

Application of modified closed biopsy in rabbit model of VX2-transplanted bone tumor

BackgroundThis study was aimed to explore the application value of modified closed biopsy technique in puncture biopsy of rabbit VX2 transplanted bone tumor model.MethodsVX2 tumor was transplanted into the bilateral tibia of 30 rabbits through the tibial plateau to make the model of VX2 transplanted bone tumor. Seven days after modeling, the proximal tibia biopsy was performed under the guidance of X-ray, and the biopsy specimen was examined pathologically. The left leg was biopsied with modified closed biopsy technique (experimental group), and the right leg was biopsied with hollow needle (control group). After 14 days of modeling, all rabbits were killed after X-ray examination around the puncture hole, and the soft tissue around the puncture hole was taken for pathological examination, and the expression levels of PCNA and CD34 in the tissue extract were detected by enzyme-linked immunosorbent assay (ELISA).ResultsBy the end of the experiment, a total of 3 rabbits died, and finally, 27 rabbits were included in the study. Tumor cells were detected in all the intramedullary specimens obtained by puncture biopsy. On the 14th day after modeling, X-ray showed that the occurrence rate of periosteal reaction and extraosseous high-density shadow around the puncture hole was 14.81% (4/27) in the experimental group and 40.74% (11/27) in the control group. The difference was statistically significant (P<0.05). The pathological results of soft tissue around the puncture hole showed that the tumor cell metastasis rate was 29.63% (8/27) in the experimental group and 100% (27/27) in the control group, and the difference was statistically significant (P<0.05). The expression levels of PCNA and CD34 in the experimental group were lower than those in the control group (P < 0.05).ConclusionBoth the modified closed biopsy technique and needle aspiration biopsy can provide sufficient biopsy tissue for the diagnosis of VX2-transplanted bone tumor in rabbits. At the same time, the improved closed biopsy technique has a certain application value in preventing local metastasis of tumor cells along the puncture channel.

Diffusion kurtosis imaging assessment of the response to radiotherapy in a VX2 bone tumor model: an animal study.

Neoadjuvant radiotherapy plays a vital role in the treatment of malignant bone tumors, and non-invasive imaging methods are needed to evaluate the response to treatment. To assess the value of diffusion kurtosis imaging (DKI) for monitoring early response to radiotherapy in malignant bone tumors. Treatment response was evaluated in a rabbit VX2 bone tumor model (n = 35) using magnetic resonance imaging (MRI), DKI, and histopathologic examinations. Subjects were divided into three groups: pre-treatment, post-treatment, and control groups. The post-treatment group was subclassified into good response and poor response groups according to the results of histopathologic examination. Apparent diffusion coefficient (ADC) and DKI parameters (mean diffusion coefficient [MD] and mean kurtosis [MK]) were recorded. The relationship between ADC, DKI parameters, and histopathologic changes after radiotherapy was determined using Pearson's correlation coefficient. The diagnostic performance of these parameters was assessed using receiver operating characteristic analysis. MD in the good response group was higher after treatment than before treatment (P < 0.001) and higher than that in the poor response group (P = 0.009). MD was highly correlated with tumor cell density and apoptosis rate (r = -0.771, P < 0.001 and r = 0.625, P < 0.001, respectively). MD was superior to other parameters for determining the curative effect of radiotherapy, with a sensitivity of 75.0%, specificity of 100.0%, and area under the curve of 0.917 (P < 0.001). The correlations between MD, tumor cell density, and apoptosis suggest that MD could be useful for assessing the early response to radiotherapy in rabbit VX2 malignant bone tumors.

Image-Guided Radiofrequency Hyperthermia (RFH)-Enhanced Direct Chemotherapy of Hepatic Tumors: The Underlying Biomolecular Mechanisms.

PurposeTo evaluate the treatment effect of radiofrequency-induced hyperthermia (RFH) combined with intra-tumoral chemotherapy for rabbit VX2 liver tumors and explore the underlying mechanism that drives local hyperthermia-enhanced chemotherapy.Materials and MethodsVX2 cell lines and rabbits with liver VX2 tumors were randomly allocated to four treatment groups including: (1) combination therapy of Doxorubicin (DOX) plus hyperthermia/RFH (n=6); (2) DOX only; (3) hyperthermia/RFH only (n=6); and (4) phosphate-buffered saline-treated control (n=6). Cell viability and doxorubicin uptake by VX2 tumor cells were assayed using flow cytometry and fluorescence microscopy 24 h after treatments. Western blot was used to evaluate the expression level of heat shock protein 70 (HSP70) in tumor cells and tissues. For the harvested VX2 tumors, fluorescence microscopy was used to evaluate the distribution and penetration of doxorubicin in tumor tissues and HSP70 expression was analyzed by Western blot and immunohistochemistry.ResultsRFH enhanced the chemotherapeutic effect of doxorubicin in VX2 cells and rabbit liver VX2 tumors resulting in higher apoptosis and lower cell viability. Flowcytometry of VX2 cells showed more apoptotic cells in combination therapy of hyperthermia and DOX, compared with other three groups in-vitro experiments (45.80 ± 1.27% vs 20.66 ± 0.71%, vs 15.16 ± 0.81% and 0.62 ± 0.06%, respectively, p<0.01). The quantitative analysis by Western blot and immunohistochemistry showed increased expression of HSP70 in both VX2 tumor cells (1.28 ± 0.13 vs 0.64 ± 0.13 vs 0.83 ± 0.10 vs 0.15 ± 0.03, respectively, p<0.05) and tumors (1.47 ± 0.13 vs 0.51 ± 0.13 vs 0.74 ± 0.11 vs 0.16 ± 0.04, respectively, p <0.01). Fluorescence microscopy showed increased uptake of DOX in tumor cells in the combination therapy group.ConclusionsRFH/hyperthermia enhanced the chemotherapeutic effect of DOX in VX2 tumors by promoting the uptake of DOX and the expression HSP70 in tumors.