Dynamic contrast-enhanced magnetic resonance imaging assessment of residual tumor angiogenesis after insufficient microwave ablation and donafenib adjuvant therapy

To analyze the correlation between dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) permeability parameters and serum vascular endothelial growth factor (VEGF) levels in a rabbit VX2 liver cancer model with insufficient microwave ablation (MWA), to observe the dynamic changes in residual tumor angiogenesis in the short term after MWA, and to assess the effectiveness of donafenib as adjuvant therapy. Forty rabbits with VX2 liver tumors were randomly divided into three groups: an insufficient MWA group (n = 15), a combined treatment group (n = 15) and a control group (n = 10). The dynamic changes in VEGF expression after MWA and the effectiveness of donafenib as adjuvant therapy were evaluated by DCE-MRI and serum VEGF levels before surgery and 1, 3, 7, and 14 days after surgery. The correlation between the volume translate constant (Ktrans) of DCE-MRI parameters and serum VEGF levels fluctuated after ablation, but the coefficient was always positive (all p < 0.001). Repeated-measures ANOVA revealed significant changes in the serum VEGF concentration (F = 40.905, p < 0.001; partial η2 = 0.689), Ktrans (F = 13.388, p < 0.001; partial η2 = 0.420), and tumor diameter in each group (F = 34.065, p < 0.001; partial η2 = 0.648) at all five time points. Pairwise comparisons showed that the serum VEGF level, Ktrans value and tumor diameter in the insufficient MWA group and combined treatment group were significantly lower at 1 d than in the control group, but these values gradually increased over time (all p < 0.05). Ktrans and tumor diameter were significantly greater in the insufficient MWA group than in the control group at 14 days (all p < 0.05). The serum VEGF concentration, Ktrans, and tumor diameter were significantly lower in the combined treatment group than in the other two groups at 3, 7, and 14 days (all p < 0.05). Ktrans is positively correlated with the serum VEGF concentration. Ktrans and the serum VEGF concentration changed significantly after treatment with insufficient ablation or in combination with donafenib, and Ktrans may change faster. Insufficient MWA promotes the progression of residual tumors. Adjuvant treatment with donafenib is effective.

Biological efficacy of simulated radiolabeled Lipiodol® ultra-fluid and microspheres for various beta emitters: study based on VX2 tumors

BACKGROUND

Radioembolization is one therapeutic option for the treatment of locally early-stage hepatocellular carcinoma. The aim of this study was to evaluate the distribution of Lipiodol® ultra-fluid and microspheres and to simulate their effectiveness with different beta emitters (90Y, 188Re, 32P, 166Ho, 131I, and 177Lu) on VX2 tumors implanted in the liver of 30 New Zealand rabbits.

RESULTS

Twenty-three out of 30 rabbits had exploitable data: 14 in the group that received Lipiodol® ultra-fluid (group L), 6 in the group that received microspheres (group M), and 3 in the control group (group C). The histologic analysis showed that the Lipiodol® ultra-fluid distributes homogeneously in the tumor up to 12 days after injection. The X-ray μCT images showed that Lipiodol® ultra-fluid has a more distal penetration in the tumor than microspheres. The entropy (disorder of the system) in the L group was significantly higher than in the M group (4.06 vs 2.67, p = 0.01). Equivalent uniform biological effective doses (EUBED) for a tumor-absorbed dose of 100 Gy were greater in the L group but without statistical significance except for 177Lu (p = 0.03). The radionuclides ranking by EUBED (from high to low) was 90Y, 188Re, 32P, 166Ho, 131I, and 177Lu.

CONCLUSIONS

This study showed a higher ability of Lipiodol® ultra-fluid to penetrate the tumor that translated into a higher EUBED. This study confirms 90Y as a good candidate for radioembolization, although 32P, 166Ho, and 188Re can achieve similar results.

A preliminary study on the establishment of a cyst and cystic neoplasm tissue-mimicking model

Context

The present experimental models of cystic diseases are not adequate and require further investigation.

Aim

In this study, a new way of producing a tissue-mimicking model of cysts and cystic neoplasms was evaluated.

Settings and Design

To simulate cysts and cystic neoplasms, ex vivo rabbit normal bladders and VX2-implanted tumor bladders were produced, fixed, and embedded in agarose gel.

Methods and Materials

The samples were classified into four groups based on tumor features and the maximal transverse diameter of the rabbit bladder, which were assessed using computer tomography (CT) imaging and statistically analyzed.

Statistical Analysis Used

Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) software. The t-test was used for analyzing enumeration data.

Results

Twenty-one rabbit bladders (21/24) were successfully removed and prepped for this experiment, comprising eleven normal bladders (11/24) and ten implanted with VX2 tumors (10/24). The gelling ingredient used to form the visualization and fixation matrix was agarose at a concentration of 4 g/200 mL. The temperature of the agarose solution was kept constant at 40-45°C, which is the optimal temperature range for ex vivo normal bladder and implanted VX2 tumor bladder insertion. The average time required to embed and fix the bladders in agarose gel was 45.0 ± 5.2 minutes per instance. The gel-fixing matrix's strength and light transmittance were enough for building the models.

Conclusion

We created an experimental tissue-mimicking model of cysts and cystic neoplasms with stable physicochemical features, a safe manufacturing method, and high repeatability. These models may be used to assist with cystic lesion diagnosis and treatment techniques.

A comparative study of establishing rabbit vertebral tumor model by two ways of CT-guided percutaneous puncture

Objective

To investigate the difference of tumor formation rate of rabbit vertebral tumor model established by percutaneous injection of V×2 tumor tissue suspension and tumor mass under computed tomography (CT) guidance, and the imaging findings of CT, magnetic resonance images (MRI) and positron emission tomography with computed tomography (PET/CT) at 7 days, 14 days and 21 days after implantation, and preliminarily verify the safety and feasibility of microwave ablation (MWA), percutaneous vertebroplasty (PVP) and microwave ablation combined with percutaneous vertebroplasty (MWA + PVP) in rabbit VX2 vertebral tumor model.

Methods

Thirty healthy New Zealand rabbits were randomly allocated to tissue suspension group and tumor block group, with 15 rabbits for each group. The VX2 tumor block and mixed suspension were inoculated into the L5 vertebral body under CT-guided percutaneous puncture. The PET/CT, MRI and CT examinations were performed at 7, 14 and 21 days after implantation. Fisher exact probability test was used to compare the success rate of the two implantation methods and the tumor display rate at each time point of the three examination methods. Observe the paralysis of tumor-forming rabbits, and immediately perform MWA/PVP/MWA + PVP treatment according to groups after paralysis to verify the safety and feasibility of treatment.

Results

A total of 18 experimental rabbits were successfully modeled in two groups, of which the success rate was 26.6% (4/15) in tissue suspension group and 93.3% (14/15) in tumor block group, with statistically significant differences between two groups (P < 0.01). The tumor display rates by PET/CT, MRI and CT at each time point after implantation were: 83.3% (15/18), 16.6% (3/18), and 0% (0/18) at 7 days after implantation; 100% (18/18), 88.8% (16/18), and 11.1% (2/18) at 14 days after implantation; and 100% (18/18), 100% (18/18), 77.7% (14/18) at 21 days after implantation. The average paralysis time of 18 experimental rabbits successfully modeled was 24.44 ± 2.38 days, and MWA/PVP/MWA + PVP treatment was performed in groups immediately after paralysis. Except for 2 rabbits who died due to anesthesia overdose during anesthesia before treatment, the remaining 16 rabbits were successfully treated with MWA/PVP/MWA + PVP, and the technical success rate was 100% (16/16). In MWA group, one experimental rabbit was randomly selected and killed after ablation, and histopathological examination (H and E staining) was performed together with 2 experimental rabbits who died of anesthesia. The pathological changes before and after ablation were compared. The survival time of the remaining 15 experimental rabbits varied from 3 to 8 days after treatment.

Conclusion

The success rate of establishing rabbit vertebral tumor model by injecting tumor masses under the CT-guided percutaneous puncture is high, and the following MWA and PVP treatment can be successfully conducted. PET/CT is the most sensitive method for early detection of tumor compared with MRI and CT. Spectral Presaturation with Inversion Recovery (SPIR) sequence can significantly improve the detection rate of smaller tumors by MRI and shorten the detection time.

Effects of microwave ablation on cysts and cystic neoplasms with tissue-mimicking model: an ex vivo study

BACKGROUND AND PURPOSE

Microwave ablation (MWA) is a promising modality that needs to be further investigated for cystic lesions. The present study aimed to determine the effects of MWA on cysts and cystic neoplasms with a tissue-mimicking model.

METHODS

Twenty New Zealand White rabbits were randomly divided into Group A (cyst mimic models, n = 10, φ = 5 cm) and Group B (cystic neoplasm mimicking models, n = 10, φ = 5 cm). For each group, ex vivo rabbit healthy bladder and VX2-implanted tumor bladder were fixed and embedded in agarose gel to mimic cyst and cystic neoplasm. In the MWA experimental subgroups, microwave antennas guided by computed tomography (CT) were introduced into these models. A system thermometer was placed at the outer edge of the bladder wall to monitor temperature changes. Immediately after MWA, ex vivo rabbit healthy bladders and VX2-implanted tumor bladders were harvested for gross anatomy and prepared for pathological evaluation.

RESULTS

A total of twenty cyst and cystic neoplasm mimicking models were successfully developed. Ninety percent of the MWA procedures were successful, and no peri-procedural complications were encountered. The temperature of the cystic wall increased with duration in both MWA experimental subgroups and an effective ablation temperature (>60 °C) was achieved. Pathological examination of the cyst and cystic neoplasm mimic models revealed degenerative necrosis of the bladder wall mucosal epithelial cells, loss of bladder wall tissue structure and coagulative necrosis of VX2 tumor cells.

CONCLUSION

Our data indicate that MWA could cause thermal damage to the tissue structure of cyst and cystic neoplasm, and it is an effective technique for treating cystic diseases.HIGHLIGHTSex vivo rabbit healthy bladder and VX2-implanted tumor bladder were fixed and embedded in agarose gel to mimic cyst and cystic neoplasm.The temperature of the cystic wall increased with MWA duration and an effective ablation temperature (> 60 °C) was achieved.MWA could cause thermal damage to the tissue structure of the cyst and cystic neoplasm and it is effective in treating cystic diseases, as assessed by histopathology.

Cell-free DNA and circulating tumor cell kinetics in a pre-clinical head and neck Cancer model undergoing radiation therapy

BACKGROUND

Monitoring circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs), known as liquid biopsies, continue to be developed as diagnostic and prognostic markers for a wide variety of cancer indications, mainly due to their minimally invasive nature and ability to offer a wide range of phenotypic and genetic information. While liquid biopsies maintain significant promising benefits, there is still limited information regarding the kinetics of ctDNA and CTCs following radiation therapy which remains a vital treatment modality in head and neck cancers. This study aims to describe the kinetics of ctDNA and CTCs following radiation exposure in a preclinical rabbit model with VX2 induced buccal carcinoma.

METHODS

Seven rabbits were inoculated with VX2 cells in the buccal mucosa and subjected to radiation. At selected time points, blood sampling was performed to monitor differing levels of ctDNA and CTC. Plasma ctDNA was measured with quantitative PCR for papillomavirus E6 while CTCs were quantified using an immunomagnetic nanoparticles within a microfluidic device. Comparisons of CTC detection with EpCAM compared to multiple surface markers (EGFR, HER2 and PSMA) was evaluated and correlated with the tumor size.

RESULTS

Plasma ctDNA reflects the overall tumor burden within the animal model. Analysis of correlations between ctDNA with tumor and lymph node volumes showed a positive correlation (R = 0.452 and R = 0.433 [p < 0.05]), respectively. Over the course of treatment, ctDNA levels declined and quickly becomes undetectable following tumor eradication. While during the course of treatment, ctDNA levels were noted to rise particularly upon initiation of radiation following scheduled treatment breaks. Levels of CTCs were observed to increase 1 week following inoculation of tumor to the primary site. For CTC detection, the use of multiple surface markers showed a greater sensitivity when compared to detection using only EpCAM. Plasma CTC levels remained elevated following radiation therapy which may account for an increased shedding of CTCs following radiation.

CONCLUSION

This study demonstrates the utility of ctDNA and CTCs detection in response to radiation treatment in a preclinical head and neck model, allowing for better understanding of liquid biopsy applications in both clinical practice and research development.

Super-Resolution Ultrasound Localization Microscopy on a Rabbit Liver VX2 Tumor Model: An Initial Feasibility Study

Ultrasound localization microscopy can image microvasculature in vivo without sacrificing imaging penetration depth. However, the reliance on super-resolution inference limits the applicability of the technique because subpixel tissue motion can corrupt microvascular reconstruction. Consequently, the majority of previous pre-clinical research on this super-resolution procedure has been restricted to low-motion experimental models with ample motion correction or data rejection, which precludes the imaging of organ sites that exhibit a high degree of respiratory and other motion. In this article, we present a novel anesthesia protocol in rabbits that induces safe, controllable periods of apnea to enable the long image-acquisition times required for ultrasound localization microscopy. We apply this protocol to a VX2 liver tumor model undergoing sorafenib therapy and compare the results to super-resolution images from conventional high-dose isoflurane anesthesia. We find that the apneic protocol was necessary to correctly identify the poorly vascularized tumor cores, as verified by immunohistochemistry, and to reveal the tumoral microvascular architecture.

Transcatheter arterial chemoembolization (TACE) with iRGD peptide in rabbit VX2 liver tumor

Purpose

Transcatheter arterial chemoembolization (TACE) is the first-line therapy for unresectable hepatocellular carcinoma (HCC). However, its therapeutic effects are hampered by the poor distribution of anticancer drugs in tumors. iRGD, a novel tumor-penetrating peptide, enhances the penetration distance and therapeutic efficacy of anticancer drugs. Herein, we evaluated the therapeutic effects of iRGD coupled with TACE in the rabbit VX2 liver tumor model.

Subjects and Methods

This study had two stages: tumor permeability assay and anticancer efficacy evaluation. In the tumor permeability assay, we coadministered TACE with either iRGD + lipiodol-doxorubicin emulsion (LDE) or LDE in the rabbit VX2 liver tumor model. We evaluated the doxorubicin (DOX) distribution at predetermined times by immunofluorescence microscopy. To evaluate anticancer efficacy, we administered saline, LDE, or iRGD + LDE to tumor-grafted rabbits. We measured tumor volume using magnetic resonance scanning. We quantified the expression levels of Bax, Bcl-2, and cleaved caspase-3 using Western blot (WB) analysis and determined the apoptosis rate in tumor cells using transferase-mediated dUTP nick-end labeling assay.

Results

The iRGD + LDE infusion significantly increased the DOX concentration and DOX penetration in tumors compared with the LDE infusion (P < 0.05). The antitumor efficacy of the iRGD + LDE in tumor inhibition was higher than that of the other treatments (P < 0.05). Besides, iRGD + LDE induced more apoptosis (P < 0.05).

Conclusions

We demonstrated that iRGD coadministered with TACE is effective against HCC.

Biomembrane formation after radiofrequency ablation prevents bone cement extravasation during percutaneous vertebroplasty for treating vertebral metastases with posterior margin destruction: An animal study

Aims

We aimed to investigate the feasibility, safety, and efficacy of radiofrequency ablation (RFA) combined with percutaneous vertebroplasty (PVP) for treating VX2 vertebral metastases with posterior margin destruction in a rabbit model.

Materials and Methods

Sixty rabbit models of VX2 vertebral metastases with posterior margin destruction were constructed through computed tomography (CT)-guided percutaneous puncture and randomly divided into four groups of 15 rabbits each: Groups A, RFA+PVP; B, PVP; C, RFA; and D, control. Five rabbits in each group were sacrificed within 24 h of the procedure. Pathological examination and immunohistochemical staining revealed the presence of a biomembrane barrier at the tumor edge; furthermore, bone cement leakage into the spinal canal was observed. The survival time of the remaining rabbits per group was observed, and the differences were analyzed.

Results

CT scans of Group A and C rabbits revealed a low-density band around the tumor ablation region. Bone cement leakage rate significantly differed between Groups A and B (20% vs. 100%; P < 0.05). The average postoperative survival times of Group A, B, C, and D rabbits were 16.72 ± 0.93, 7.26 ± 0.75, 7.80 ± 1.30, and 3.84 ± 1.24 days, respectively, showing a significant difference between Group A and the remaining groups (P < 0.05).

Conclusions

The biomembrane barrier formed at the tumor edge after RFA can prevent bone cement leakage into the spinal canal, reducing spinal cord injury and prolonging the survival time.

Fast and Selective Ablation of Liver Tumors by High-Intensity Focused Ultrasound Using a Toroidal Transducer Guided by Ultrasound Imaging: The Results of Animal Experiments

This study demonstrated that high-intensity focused ultrasound (HIFU) produced with an intra-operative toroidal-shaped transducer causes fast, selective liver tumor ablations in an animal model. The HIFU device is composed of 256 emitters working at 3 MHz. A 7.5 MHz ultrasound imaging probe centered on the HIFU transducer guided treatment. VX2 tumor segments (25 mg) were implanted into the right lateral liver lobes of 45 New Zealand rabbits. The animals were evenly divided into groups 1 (toroidal HIFU ablation), 2 (surgical resection) and 3 (untreated control). Therapeutic responses were evaluated with gross pathology and histology 11 d post-treatment. Toroidal transducer-produced HIFU ablation (average ablation rate 10.5 cc/min) allowed fast and homogeneous tumor treatment. Sonograms showed all ablations. VX2 tumors were completely coagulated and surrounded by safety margins without surrounding-organ secondary HIFU lesions. HIFU group tumor volumes at autopsy (39 mm³) were significantly lower than control group volumes (2610 mm³, p < 0.0001). HIFU group tumor metastasis (27%) was lower than resected (33%) and control (67%) group metastasis. Ultrasound imaging, gross pathology and histology results supported these outcomes. HIFU procedures had no complications. Rabbit liver tumor ablation using a toroidal HIFU transducer under ultrasound imaging guidance might therefore be an effective intra-operative treatment for localized liver metastases.

Native T1 Mapping Magnetic Resonance Imaging as a Quantitative Biomarker for Characterization of the Extracellular Matrix in a Rabbit Hepatic Cancer Model

To characterize the tumor extracellular matrix (ECM) using native T1 mapping magnetic resonance imaging (MRI) in an experimental hepatic cancer model, a total of 27 female New Zealand white rabbits with hepatic VX2 tumors were examined by MRI at different time points following tumor implantation (day 14, 21, 28). A steady-state precession readout single-shot MOLLI sequence was acquired in a 3 T MRI scanner in prone position using a head-neck coil. The tumors were segmented into a central, marginal, and peritumoral region in anatomical images and color-coded T1 maps. In histopathological sections, stained with H&E and Picrosirius red, the regions corresponded to central tumor necrosis and accumulation of viable cells with fibrosis in the tumor periphery. Another region of interest (ROI) was placed in healthy liver tissue. T1 times were correlated with quantitative data of collagen area staining. A two-way repeated-measures ANOVA was used to compare cohorts and tumor regions. Hepatic tumors were successfully induced in all rabbits. T1 mapping demonstrated significant differences between the different tumor regions (F(1.43,34.26) = 106.93, p < 0.001) without interaction effects between time points and regions (F(2.86,34.26) = 0.74, p = 0.53). In vivo T1 times significantly correlated with ex vivo collagen stains (area %), (center: r = 0.78, p < 0.001; margin: r = 0.84, p < 0.001; peritumoral: r = 0.73, p < 0.001). Post hoc tests using Sidak’s correction revealed significant differences in T1 times between all three regions (p < 0.001). Native T1 mapping is feasible and allows the differentiation of tumor regions based on ECM composition in a longitudinal tumor study in an experimental small animal model, making it a potential quantitative biomarker of ECM remodeling and a promising technique for future treatment studies.

Evaluation of neurapheresis therapy in vitro: a novel approach for the treatment of leptomeningeal metastases

Background

Leptomeningeal metastases (LM), late-stage cancer when malignant cells migrate to the subarachnoid space (SAS), have an extremely poor prognosis. Current treatment regimens fall short in effectively reducing SAS tumor burden. Neurapheresis therapy is a novel approach employing filtration and enhanced circulation of the cerebrospinal fluid (CSF). Here, we examine the in vitro use of neurapheresis therapy as a novel, adjunctive treatment option for LM by filtering cells and augmenting the distribution of drugs that may have the potential to enhance the current clinical approach.

Methods

Clinically relevant concentrations of VX2 carcinoma cells were suspended in artificial CSF. The neurapheresis system’s ability to clear VX2 carcinoma cells was tested with and without the chemotherapeutic presence (methotrexate [MTX]). The VX2 cell concentration following each filtration cycle and the number of cycles required to reach the limit of detection were calculated. The ability of neurapheresis therapy to circulate, distribute, and maintain therapeutic levels of MTX was assessed using a cranial–spinal model of the SAS. The distribution of a 6 mg dose was monitored for 48 h. An MTX-specific ELISA measured drug concentration at ventricular, cervical, and lumbar sites in the model over time.

Results

In vitro filtration of VX2 cancer cells with neurapheresis therapy alone resulted in a 2.3-log reduction in cancer cell concentration in 7.5 h and a 2.4-log reduction in live-cancer cell concentration in 7.5 h when used with MTX. Cranial–spinal model experiments demonstrated the ability of neurapheresis therapy to enhance the circulation of MTX in CSF along the neuraxis.

Conclusion

Neurapheresis has the potential to act as an adjunct therapy for LM patients and significantly improve the standard of care.

Evaluation of the MR and pathology characteristics immediately following percutaneous MR-guided microwave ablation in a rabbit kidney VX2 tumor implantation model

Purpose: This study aimed to evaluate the immediate efficacy of magnetic resonance (MR)-guided microwave ablation (MWA) in rabbit kidneys implanted with VX2 tumors.Materials and methods: MR-guided MWA was performed in eight VX2 tumor-bearing rabbits. MR images after ablation were obtained and analyzed. The differences between the tissue specimens and MR images obtained after ablation were compared.Results: On the three-dimensional volumetric interpolated breath-hold T1-weighted (3D-VIBE-T1WI) sequence, a low signal intensity indicated the primary tumor at the center of the ablation area, which was surrounded by a peripheral high-signal area. The signal for the primary tumor in the fast spin-turbo spin-echo T2-weighted (FS-TSE-T2WI) sequence was lower than before, and the ablation zone showed a low signal that completely covered the primary tumor. There was no significant difference in volume among the low-signal areas of the primary tumor on FS-TSE-T2WI before MWA, the central low-signal area on 3D-VIBE-T1WI after MWA, and the tumor coagulation necrosis area on the tissue specimens (p > 0.05). No significant difference was found in the volume of ablation zones among the tissue specimens, the high-signal area around the lesion on the 3D-VIBE-T1WI sequence, and the low-signal area covering the lesion on the FS-TSE-T2WI sequence (p > 0.05).Conclusion: Magnetic resonance imaging (MRI) is an effective method for immediate efficacy evaluation of rabbit renal VX2 tumors after MWA and can serve as a valuable reference for the clinical assessment of post-ablative renal tumors.

Comparison of anesthesia and tumor implantation methods for establishing rabbit VX2 hepatocarcinoma

In this study, we compared different anesthesia and operation methods for modeling VX2 hepatocarcinoma in rabbits. Forty New Zealand white rabbits were randomly divided into three groups: A, B, and C. Group A underwent ultrasound-guided implantation and intravenous anesthesia; Group B underwent ultrasound-guided implantation and inhalation anesthesia; Group C underwent laparotomy implantation and intravenous anesthesia. Anesthesia and operation differences were compared between groups A and B, and A and C, respectively. We used magnetic resonance imaging (MRI) to assess tumor formation and growth, and pathological examination and immunohistochemistry to confirm the biological characteristics of the specimens. The anesthetic preparation and postoperative resuscitation times were shorter in group A compared to group B; there were no significant between-group differences in the intraoperative satisfactory effect rate or mortality rate. The operation time, incision length, hemorrhage volume, and leukocyte counts were lower in group A than group C; there were no significant between-group differences in the postoperative infection rate or mortality rate. MRI revealed that the celiac implantation rate decreased dramatically in groups A and B; there were no significant between-group differences in the largest tumor diameter, tumorigenesis rate, intrahepatic multifocal implantation rate, or abdominal wall invasion rate. Ten samples were confirmed by pathological examination and immunohistochemistry to have VX2 tumors. To conclude, using an inhalation-based anesthetic method is beneficial for improving the efficiency of the VX2 tumor implantation operation. Compared with laparotomy implantation, ultrasound-guided implantation required less operation time, had lower levels of internal damage, and had a lower celiac implantation rate.

Combined microwave ablation and antiangiogenic therapy to increase local efficacy

Purpose: We aim to evaluate the efficacy, safety and survival time of microwave ablation (MWA) with adjuvant antiangiogenic therapy-endostatin in animal models.Material and methods: A total of 40 rabbits successfully implanted with VX2 tumors were randomly assigned to four experimental groups: Group A underwent only microwave ablation of the tumors; Group B received only antiangiogenic drugs endostatin; Group C received endostatin immediately after MWA; Group D followed up without treatment.Results: Two months post-treatment, tumor sizes of Group A and Group C were reduced to 1.936 ± 0.373 cm³ and 1.592 ± 0.382 cm³, respectively. However, tumors grew to 15.091 ± 1.735 cm³ and 47.825 ± 7.664 cm³ in Group B and the control group. Three months post-treatment, tumor sizes in Group A and Group C maintained as 1.395 ± 0.394 cm³ and 1.482 ± 0.305 cm³, significantly smaller than Group B (35.277 ± 6.019 cm³). All animals in the control group died, while four (40%) survived in Group B (Endo Group). The numbers of survivals in Groups A and C were seven (70%) and eight (80%), respectively. The lowest metastasis rate (2/10, 20%) was observed in Group C (combination therapy).Conclusion: The combination of MWA and antiangiogenic therapy triggered a significant reduction in the growth rate and metastases of tumors and may potentially improve survivals.

Simultaneous Passive Acoustic Mapping and Magnetic Resonance Thermometry for Monitoring of Cavitation-Enhanced Tumor Ablation in Rabbits Using Focused Ultrasound and Phase-Shift Nanoemulsions

Thermal ablation of solid tumors via focused ultrasound (FUS) is a non-invasive image-guided alternative to conventional surgical resection. However, the usefulness of the technique is limited in vascularized organs because of convection of heat, resulting in long sonication times and unpredictable thermal lesion formation. Acoustic cavitation has been found to enhance heating but requires use of exogenous nuclei and sufficient acoustic monitoring. In this study, we employed phase-shift nanoemulsions (PSNEs) to promote cavitation and incorporated passive acoustic mapping (PAM) alongside conventional magnetic resonance imaging (MRI) thermometry within the bore of a clinical MRI scanner. Simultaneous PAM and MRI thermometry were performed in an in vivo rabbit tumor model, with and without PSNE to promote cavitation. Vaporization and cavitation of the nanoemulsion could be detected using PAM, which led to accelerated heating, monitored with MRI thermometry. The maximum heating assessed from MRI was well correlated with the integrated acoustic emissions, illustrating cavitation-enhanced heating. Examination of tissue revealed thermal lesions that were larger in the presence of PSNE, in agreement with the thermometry data. Using fixed exposure conditions over 94 sonications in multiple animals revealed an increase in the mean amplitude of acoustic emissions and resulting temperature rise, but with significant variability between sonications, further illustrating the need for real-time monitoring. The results indicate the utility of combined PAM and MRI for monitoring of tumor ablation and provide further evidence for the ability of PSNEs to promote cavitation-enhanced lesioning.

Targeted Yttrium 89-Doxorubicin Drug-Eluting Bead-A Safety and Feasibility Pilot Study in a Rabbit Liver Cancer Model

The purpose of this article is to evaluate feasibility and safety of the cancer targeting (radio)-chemoembolization drug-eluting bead (TRCE-DEB) concept drug SW43-DOX-L-NETA(⁸⁹Y) DEB for the intra-arterial treatment of VX2 rabbit liver tumors. The treatment compound comprises of the sigma-2 receptor ligand SW43 for cancer targeting, doxorubicin (DOX), and ⁸⁹yttrium (⁸⁹Y) as nonradioactive surrogate for therapeutic (yttrium-90, lutetium-177) and imaging (yttrium-86) radioisotopes via the chelator L-NETA. Ten New Zealand white rabbits with VX2 tumor allografts were used. SW43-DOX-⁸⁹Y was synthesized, loaded onto DEB (100 μL; 100-300 μm), and administered intra-arterially in six rabbits at increasing doses (0.2-1.0 mg/kg). As controls, two rabbits each received either doxorubicin IV (0.3 mg/kg) or no treatment. Consecutive serum analysis for safety and histopathological evaluation after sacrifice were performed. One-Way ANOVA incl. Bonferroni Post-Hoc test was performed to compare groups. Targeted compound synthesis, loading onto DEB, and intra-arterial administration were feasible and successful in all cases. Serum liver enzyme levels increased in a dose dependent manner within 24 h and normalized within 3 days for 0.2/0.6 mg/kg SW43-DOX-⁸⁹Y loaded onto DEB. The two rabbits treated with 1 mg/kg SW43-DOX-⁸⁹Y had to be euthanized after 3/24 h due to worsening general condition. Histopathological necrosis increased over time in a dose depended manner with 95-100% tumor necrosis 3-7 days post treatment (0.6 mg/kg). SW43-DOX-⁸⁹Y loaded onto DEB can be formulated and safely administered at a concentration of 0.6 mg/kg. Loading with radioactive isotopes (e.g., ⁸⁶yttrium/⁹⁰yttrium/¹⁷⁷lutetium) to synthesize the targeted radio-chemoembolization drug-eluting bead (TRCE-DEB) concept drug is feasible.

Laparoscopic subperitoneal injection of chemo-loaded particles lowers tumor growth on a rabbit model of peritoneal carcinomatosis

The purpose of our study was to assess the effect of controlled-release chemotherapy on the growth and viability of peritoneal carcinomatosis treated by subperitoneal injection in a rabbit VX2 model. A model of peritoneal carcinomatosis was created by laparoscopic injection of VX2 tumor in the left and right broad ligaments of 12 White New Zealand rabbits. At day 12, each tumor was randomly treated with a peritumoral injection of 0.5 mL microspheres loaded with doxorubicin (DEM-DOX) or unloaded (DEM-BLAND). Seven days after treatment, tumor volume, tumor viability in histology, local tumor necrosis in contact with DEM, and doxorubicin concentration profile around the drug eluting microspheres (DEM) were measured. Tumor volume was significantly lower in the DEM-DOX group (3.6 ± 3.2 cm³) compared with the DEM-BLAND group (8.9 ± 5.4 cm³) (p = 0.0425). The percentage of viable tumor tissue was significantly lower in the DEM-DOX group (38% ± 17%) compared with the DEM-BLAND group (56% ± 20%) (p = 0.0202). Tissue necrosis was observed around all DEM-DOX up to a distance of 1.094 ± 0.852 mm and never observed around DEM-BLAND. Drug concentration was above the therapeutic level of 1.0 µM up to a distance of 1.4 mm from the DEM to the tumor. Laparoscopic subperitoneal injection of chemo-loaded particles is feasible and lowers tumor growth and viability in a rabbit model of peritoneal carcinomatosis after 1 week.

Induction of VX2 para-renal carcinoma in rabbits: generation of animal model for loco-regional treatments of solid tumors

Background

Animal models of para-renal cancer can provide useful information for the evaluation of tumor response to loco-regional therapy experiments in solid tumors. The aim of our study was to establish a rabbit para-renal cancer model using locally implanted VX2 tumors.

Methods

In order to generate a rabbit model of para-renal cancer, we established four hind limb donor rabbits by using frozen VX2 tumor samples. Following inoculation, rabbits were monitored for appetite and signs of pain. Viable tumors appeared as palpable nodules within 2 weeks of inoculation. Tumor growth was confirmed in all rabbits by high-resolution ultrasound analysis and histology. Once tumor growth was established, hind limb tumors extraction was used for tumor line propagation and para-renal tumor creation. Twenty-one rabbit models bearing para-renal cancer were established by implanting VX2 tumor into the para-renal capsula. Tumors developed into discreet 2–3 cm nodules within 1–3 weeks of implantation. Serial renal ultrasonography follow-up, starting 1 week after tumor implantation, was performed. Two weeks after tumor implantation, rabbits were euthanized and tumors and other organs were collected for histopathology.

Results

Tumor growth after VX2 tumor fragment implantation was confirmed in all rabbits by high-resolution ultrasound (US) imaging examinations of the para-renal regions and was measured with digital caliper. The para-renal injection of VX2 tumor fragments, achieved tumor growth in 100% of cases. All data were confirmed by histological analysis.

Conclusions

We generated for the first time, a model of para-renal cancer by surgical tumor implantation of VX2 frozen tumor fragments into rabbit’s para-renal region. This method minimizes the development of metastases and the use of non-necrotic tumors and will optimize the evaluation of tumor response to loco-regional therapy experiments.

bFGF Up-regulation Reduces Spontaneous Necrosis of VX2 Tumors Without Increasing Tumoral Microvascular Density

AIM

To determine whether up-regulation of basic fibroblast growth factor (bFGF) in VX2 cells reduces tumor necrosis.

MATERIALS AND METHODS

VX2 cells were transfected with expression vector containing cDNA of rabbit bFGF. Stable clones producing rabbit bFGF (bFGF-VX2) were selected. bFGF-VX2 (n=5) or non-transfected VX2 (control) (n=5) cells were implanted into leg muscle of 10 rabbits. The tumors were characterized 21 days after grafting.

RESULTS

Overexpression of bFGF by VX2 tumors significantly reduced necrosis (p<0.0223) and increased cell viability (p<0.0223), without effect on the mean vascular density. bFGF concentration was significantly higher in bFGF-VX2 tumors (p<0.0062) and negatively correlated with tumor volume at day 21 (ρ=-0.927, p<0.0034). Vascular endothelial growth factor concentration was significantly lower in bFGF-VX2 tumors (p<0.0105) and negatively correlated with the bFGF concentration of tumors (ρ=-0.903, p<0.0067).

CONCLUSION

The overexpression of bFGF in VX2 cells increased tumor viability and reduced necrosis, making the evaluation of long-term anticancer therapies possible in this model.

A Novel Inherently Radiopaque Bead for Transarterial Embolization to Treat Liver Cancer - A Pre-clinical Study

Purpose: Embolotherapy using microshperes is currently performed with soluble contrast to aid in visualization. However, administered payload visibility dimishes soon after delivery due to soluble contrast washout, leaving the radiolucent bead's location unknown. The objective of our study was to characterize inherently radiopaque beads (RO Beads) in terms of physicomechanical properties, deliverability and imaging visibility in a rabbit VX2 liver tumor model.

Materials and Methods: RO Beads, which are based on LC Bead® platform, were compared to LC Bead. Bead size (light microscopy), equilibrium water content (EWC), density, X-ray attenuation and iodine distribution (micro-CT), suspension (settling times), deliverability and in vitro penetration were investigated. Fifteen rabbits were embolized with either LC Bead or RO Beads + soluble contrast (iodixanol-320), or RO Beads+dextrose. Appearance was evaluated with fluoroscopy, X-ray single shot, cone-beam CT (CBCT).

Results: Both bead types had a similar size distribution. RO Beads had lower EWC (60-72%) and higher density (1.21-1.36 g/cc) with a homogeneous iodine distribution within the bead's interior. RO Beads suspension time was shorter than LC Bead, with durable suspension (>5 min) in 100% iodixanol. RO Beads ≤300 µm were deliverable through a 2.3-Fr microcatheter. Both bead types showed similar penetration. Soluble contrast could identify target and non-target embolization on fluoroscopy during administration. However, the imaging appearance vanished quickly for LC Bead as contrast washed-out. RO Beads+contrast significantly increased visibility on X-ray single shot compared to LC Bead+contrast in target and non-target arteries (P=0.0043). Similarly, RO beads demonstrated better visibility on CBCT in target arteries (P=0.0238) with a trend in non-target arteries (P=0.0519). RO Beads+dextrose were not sufficiently visible to monitor embolization using fluoroscopy.

Conclusion: RO Beads provide better conspicuity to determine target and non-target embolization compared to LC Bead which may improve intra-procedural monitoring and post-procedural evaluation of transarterial embolization.

Comparative Chemosensitivity of VX2 and HCC Cell Lines to Drugs Used in TACE

AIM

To compare the cytotoxic effects of 11 anticancer agents against VX2 and HepG2 cells in order to establish candidate drugs that can be tested preclinically on VX2 tumor model for transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

VX2 and HepG2 cells were incubated with different drug concentrations. The half-maximal inhibitory concentration (IC50) values were determined by total cell protein assay for anthracyclines, platins, irinotecan, mytomicin-C (MMC), 5-fluorouracil (5-FU) and antiangiogenics.

RESULTS

IC50 values for VX2 and HepG2 were found close for doxorubicin (0.8 μM vs. 1.1 μM), MMC (13.9 μM vs. 8.7 μM), sunitinib (32.7 vs. 33.7 μM), sorafenib (10.3 vs. 8.9 μM), lapatinib (30 vs. 18.3 μM) and different for platins and irinotecan. Oxaliplatin was less active against VX2 than HepG2 (IC50=41 μM vs. 2.7 μM), cisplatin was more active against VX2 than HepG2 (IC50=8.0 μM vs. 15.9 μM), whereas carboplatin had a low toxicity against both cell lines (70.4 μM vs. 538.3 μM). The toxicity of 5-FU against VX2 and HepG2 was low (IC50=560.6 μM vs. 323.2 μM). Irinotecan was less active against VX2 vs. HepG2 (IC50=44.5 μM vs. 15.3 μM). Bevacizumab had no effect on either of the cell lines up to 6.7 μM.

CONCLUSION

Drugs recommended for pre-clinical trials of TACE in the VX2 model are doxorubicin, sunitinib, sorafenib, MMC, lapatinib and 5-FU.

Tumor-induced VEGF-C overexpression in retroperitoneal lymph nodes in VX2 carcinoma-bearing rabbits

Objective

To establish the retroperitoneal lymph node (RLN) metastasis model of cervical carcinoma in rabbits and evaluate the relationship of vascular endothelial growth factor-C (VEGF-C) expression and the lymph node status.

Methods

Forty-eight rabbits were injected with VX2 cells or RPMI solution at muscular mucosae of the myometrium 0.5 cm away from the cervix. Animals were treated with or without cis-diamminedichloroplatinum(II) (cisplatin: DDP) and sacrificed on days 15, 21, and 27 post-VX2 or RPMI injections. Tumor mass and RLNs were examined histopathologically. Quantitative real-time PCR was used to examine the changes in VEGF-C mRNA expression. Levels of VEGF-C protein expression in tissues were determined using immunohistochemistry staining.

Results

Development of VX2 cervical carcinoma and the RLNs metastasis was confirmed with pathological examination. Significantly increased tumor volume was observed on days 15, 21, and 27 postinjection (P<0.05). The enlargement of RLNs was found on day 21. Expression of VEGF-C was significantly upregulated in peripheral white blood cells, tumor mass, and RLNs in an association with cancer progression. DDP resulted in a suppression of VEGF-C expression, whereas the influences on tumor mass and lymphatic metastasis were insignificant.

Conclusion

Elevated VEGF-C expressions in peripheral white blood cells and RLNs are associated with tumor progression and lymphatic metastasis. DDP treatment inhibits VEGF-C expression and fails to protect against metastatic cervical cancer.

Transarterial oily chemoembolization with lidamycin shows potent therapeutic efficacy in VX2 rabbit liver tumor

Transarterial oily chemoembolization (TOCE) is one of the most effective approaches for the treatment of patients with hepatocellular carcinoma (HCC), who are not suitable for surgical therapy. Lidamycin (LDM), a potent antitumor antibiotic, demonstrates good antitumor efficacy in various tumor types, both in vitro and in vivo. In this study, the antitumor efficacy of LDM combined with TOCE against the rabbit VX2 tumor was assessed. A toxicity assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) demonstrated that a combination of LDM with lipiodol did not impair the cytotoxicity of LDM against HepG2 cells in vitro. Using TOCE in rabbit VX2 tumor models, LDM showed a more powerful inhibitory effect against the tumor and lowered the expression levels of proliferating cell nuclear antigen (PCNA), cluster of differentiation 31 (CD31), and vascular endothelial growth factor (VEGF) compared to Adriamycin (ADM); moreover, this improvement was not accompanied by an increase of hepatotoxicity as shown by alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. These results suggested that LDM combined with TOCE may be a feasible strategy in HCC therapy in the future.

Experimental study of doxorubicin interventional chemotherapy in the treatment of rabbit VX2 renal transplantation carcinoma

OBJECTIVE

This study aims to explore the effect of doxorubicin interventional chemotherapy on rabbit VX2 renal transplantation carcinoma and its mechanism.

METHODS

Thirty healthy New Zealand white rabbits were chosen to establish VX2 renal transplantation carcinoma models. The experimental rabbits were randomly divided into three groups with 10 rabbits in each group. The rabbits in the control group (negative control), doxorubicin group and cisplatin group were treated with saline, 5 mg/kg doxorubicin and 2 mg/kg cisplatin respectively. The tumor volume was monitored with B-mode ultrasonography. The rabbits were anesthetized and killed after two weeks of interventional chemotherapy. The changes of Bcl-2 and Bax at the levels of mRNA and protein were analyzed with real-time PCR and immunohistochemistry.

RESULTS

The efficacy of interventional chemotherapy was evaluated with tumor volume changes monitored by B-mode ultrasonography. The tumor volume of control group and doxorubicin group was 1.29±0.60 cm(3) and 0.47±0.12 cm(3) respectively. Further fluorescence quantitative PCR detection results showed that doxorubicin could reduce the Bcl-2 expression and increase the Bax expression (P < 0.05). The result of immunohistochemistry was consistent with that of fluorescence quantitative PCR.

CONCLUSIONS

The effect of doxorubicin interventional chemotherapy on renal transplantation carcinoma is obvious and the mechanism may be related to the down-regulation of Bcl-2 expression and up-regulation of Bax expression thus inducing the apoptosis of tumor cells.

Intraperitoneal oxidative stress as an oncolytic immunomodulator?

Intraperitoneal oxidative stress effectively converts the immune response against the papillomavirus-associated rabbit VX2 carcinoma from tumor permissive to tumoricidal and leads to a sustainable oncolytic immune response that can be adoptively transferred.

In vivo assessment of intratumoral aspirin injection to treat hepatic tumors

AIM: To study the antineoplastic efficacy of 10% aspirin intralesional injection on VX2 hepatic tumors in a rabbit model.

METHODS: Thirty-two male rabbits (age: 6-9 wk; body weight: 1700-2500 g) were inoculated with VX2 hepatic tumor cells (10⁴ cells/rabbit) via supra-umbilical median laparotomy. On day 4 post-implantation, when the tumors were about 1 cm in diameter, the rabbits were randomly divided into the following groups (n = 8 each group) to assess early (24 h) and late (7 d) antineoplastic effects of intratumoral injection of 10% bicarbonate aspirin solution (experimental groups) in comparison to intratumoral injection of physiological saline solution (control groups): group 1, 24 h control; group 2, 24 h experimental; group 3, 7 d control; group 4, 7 d experimental. The serum biochemistry profile (measurements of glycemia, alkaline phosphatase, gamma-glutamyl transferase, aspartate aminotransferase, and alanine aminotransferase) and body weight measurements were obtained for all animals at the following time points: D0, before tumor implant; D4, day of treatment; D5, day of sacrifice for groups 1 and 2; D11, day of sacrifice for groups 3 and 4. Gross assessments of the abdominal and thoracic cavities were carried out upon sacrifice. The resected liver tissues, including hepatic tumors, were qualitatively (general morphology, signs of necrosis) and quantitatively (tumor area) assessed by histopathological analysis.

RESULTS: Gross examination showed no alterations, besides the left hepatic lobe tumors, had occurred in the thoracic and abdominal cavities of any animal at any time point evaluated. However, the features of the tumor foci were distinctive between the groups. Compared to the control groups, which showed normal unabated tumor progression, the aspirin-treated groups showed imprecise but limited tumor boundaries and a general red-white coloration (indicating hemorrhaging) at 24 h post-treatment, and development of yellow-white areas of a cicatricial aspect at 7 d after treatment. At all time points evaluated, all except one biochemical parameters tested within the reference range (P > 0.05); a significant increase was detected in the alkaline phosphatase level of the control group 3 on D11 (P < 0.05). At 24 h post-treatment, the aspirin-treated groups showed extensive coagulation necrosis accompanied by a remarkable absence of viable tumor foci; at 7 d after treatment, the tumors had completely disappeared in these animals and fibrous necrotic nodules had developed. In contrast, throughout the study course, the tumors of the control groups remained unchanged, showing tumor nodules without necrosis at the time point corresponding to 24 h post-treatment and increased amounts of tumor nodules at the time point corresponding to 7 d post-treatment. Quantitative analysis of the remaining tumor area revealed that the aspirin-treated groups had significantly smaller tumor foci at 24 h post-treatment (8.5% ± 0.7%) and at 7 d after treatment (11.0% ± 4.2%), compared to those in the control groups (24 h: 98.5% ± 1.5% and 7 d: 94.0% ± 2.7%; both, P < 0.005).

CONCLUSION: Intralesional injection of a 10% aspirin solution causes destruction of VX2 hepatic tumors in rabbits without evidence of relapse at 7 d after treatment administration.

Expression of hypoxia-inducible factor-1α and proliferating cell nuclear antigen in the residual tumor in rabbits after radiofrequency ablation of VX2 liver tumor with hepatic inflow occlusion

AIM: To evaluate the expression of hypoxia-inducible factor-1α (HIF-1α) and proliferating cell nuclear antigen (PCNA) in the residual tumor in rabbits after radiofrequency ablation (RFA) of VX2 liver tumor with hepatic inflow occlusion.

METHODS: A rabbit VX2 liver tumor model was established by implantation of VX2 tumor fragment into the liver. The model rabbits were divided into two groups: rabbits undergoing RFA alone (control group) and those undergoing RFA with hepatic inflow occlusion (experimental group). Radiofrequency lesions were created in vivo using a cool-tip radiofrequency electrode (parameters: burn time, 8 min; power, 30 W). The animals were sacrificed one week later. HIF-1α and PCNA expression in the residual tumor was examined by immunohistochemistry.

RESULTS: The expression of HIF-1α in the residual tumor was weakly and moderately positive in 4 and 3 rabbits in the control group, respectively. In contrast, the number of rabbits showing weakly, moderately and strongly positive HIF-1α expression were 1, 2 and 4 in the experimental group, respectively. The expression intensity of HIF-1α protein in the residual tumor was significantly higher in the experimental group than in the control group (P < 0.05). The expression of PCNA in the residual tumor was weakly, moderately and strongly positive in 3, 2 and 2 rabbits in the control group, while the number of rabbits showing weakly, moderately and strongly positive PCNA expression were 2, 4 and 1 in the experiment group, respectively. No significant difference was noted in the expression intensity of PCNA in the residual tumor between the two groups.

CONCLUSION: HIF-1α expression is upregulated in the residual tumor in rabbits after RFA of VX2 liver tumor with hepatic inflow occlusion, which may have an impact on the invasion and metastasis of residual tumor.

Evaluation of a rabbit rectal VX2 carcinoma model using computed tomography and magnetic resonance imaging

AIM: To establish a rabbit rectal VX2 carcinoma model for the study of rectal carcinoma.

METHODS: A suspension of VX2 cells was injected into the rectum wall under the guidance of X-ray fluoroscopy. Computed tomography (CT) and magnetic resonance imaging (MRI) were used to observe tumor growth and metastasis at different phases. Pathological changes and spontaneous survival time of the rabbits were recorded.

RESULTS: Two weeks after VX2 cell implantation, the tumor diameter ranged 4.1-5.8 mm and the success implantation rate was 81.8%. CT scanning showed low-density foci of the tumor in the rectum wall, while enhanced CT scanning demonstrated asymmetrical intensification in tumor foci. MRI scanning showed a low signal of the tumor on T₁-weighted imaging and a high signal of the tumor on T₂-weighted imaging. Both types of signals were intensified with enhanced MRI. Metastases to the liver and lung could be observed 6 wk after VX2 cell implantation, and a large area of necrosis appeared in the primary tumor. The spontaneous survival time of rabbits with cachexia and multiple organ failure was about 7 wk after VX2 cell implantation.

CONCLUSION: The rabbit rectal VX2 carcinoma model we established has a high stability, and can be used in the study of rectal carcinoma.

Effect of vascular occlusion on radiofrequency ablation of the liver in a rabbit VX2 tumor model

AIM: To evaluate the effects of vascular occlusion of hepatic blood flow on radiofrequency lesion and liver injury in rabbit VX2 tumor model.

METHODS: Rabbit VX2 liver tumor models were successfully established, and than they were assigned to two groups: radiofrequency ablation alone group and radiofrequency ablation with hepatic blood flow occlusion (vascular-occluded RFA) group. Radiofrequency lesions were created in vivo using a cool-tip radiofrequency electrode (radiofrequency parameters were 8 min in time and 30 W in power). The hepatic blood flow occlusion was got by pringle maneuver. Serum ALT, AST, AKP and GGT were detected before the operation and the 1^st, 3^rd, 7^th day after the operation, and the adverse events were observed. The animals were sacrificed one week later. The size, volume of necrosis lesions in the two groups were then analyzed.

RESULTS: Volume and vertical diameter of the coagulated area were significantly greater with the pringle maneuver. The parallel diameter was larger than that coagulated by standard RFA, but there were no significantly differences between the groups. Serum ALT, GGT was higher in radiofrequency ablation combined with Pringle maneuver group than radiofrequency ablation alone group at each time after the operation (P < 0.05), and serum GGT lever was gradually increased postoperatively. Differences in serum AST, AKP between the two groups at each time postoperatively were not significant. One case of vascular-occluded RFA group was complicated with mild bile leakage, one case died on the 1^st day for hemorrhage, and one case died for liver injury on the 4^th day.

CONCLUSION: Radiofrequency ablation combined with occlusion of the hepatic artery and portal vein increases the volume of necrosis when compared with radiofrequency ablation alone, but much more serious liver injuries are found, careful attention should be paid when this technique is used in clinical practice.

Combined therapy of radiofrequency ablation with transcatheter artery embolization in rabbit model of hepatic carcinoma

AIM: To investigate the safety about the combined therapy of radiofrequency ablation (RFA) with transcatheter artery embolization (TAE) in rabbits with VX2 hepatic carcinoma.

METHODS: VX2 tumor tissues were implanted into the rabbit's liver to establish liver cancer model. Thirty-six rabbits with hepatic carcinoma were assigned to 4 groups randomly (n = 9). Group A received RFA treatment only; group B, C, D received TAE treatment 1, 4, 7 d prior to RFA treatment respectively. The ALT and UREA levels of the experimental rabbits were measured before and after each treatment.

RESULTS: Decreased appetite, drowsiness and dispiritedness were observed in the rabbits, especially in group B and C. No death was observed in group A and group D, but there were 3 deaths in group B and 2 deaths in group C. ALT levels were the highest at the first day in all groups. The difference was significant at the first day between group B (385.0 ± 213.1 U/L), C (289.2 ± 192.6 U/L) and A (178.4 ± 49.2 U/L), D (208.2 ± 65.5 U/L) respectively (P < 0.05), but not significant between group B and C, group A and D; There were no differences between each group at the 4th day and 7th day. No statistical significance in UREA levels was observed among the four groups.

CONCLUSION: RFA at 1, 4 d after TAE might impact liver function severely. RFA, is relatively safe at 7 d after TAE treatment. Combined therapy of RFA and TAE exerts no impact on renal function in all groups.