Implantation of VX2 carcinoma into the liver of rabbits: a comparison of three direct-injection methods

Establishment of metastatic liver carcinoma model by implanting AX7 cells into rabbit liver, and its histological findings

Background: Progression of metastatic liver carcinoma from any original cancer is aggressive and the prognosis is very poor. Therefore the new model that is easily approachable to study the propagation and prognosis of metastatic liver carcinoma is necessary. The aim of this study is to confirm the tumor formation and metastatic activity of anaplastic thyroid cancer and to support the research basis for the next generation cancer treatment that is to be developed, by carrying out additional experiments like cytokine stimulation. We investigated sequential findings of immunohistochemistry of rabbit hepatic malignancy induced by AX7 cells. Methods: 13 rabbits implanted with AX7 cells directly into liver parenchyme with laparotomy were investigated by histopathology examination, immunohistochemistry, which is useful for the evaluation of metastatic cancer angiogenesis. Growing tissue at the edge of the mass was collected and placed in the petri dish filled with saline. After removing necrotic and fibrous tissue, tumor tissue was cut into pieces, placed in saline, and extracted during the experiment. Results: Tumor growth and malignancy was confirmed on the 10th day after AX7 cells were implanted into liver. Positive for VEGF staining was found in the cytoplasm or cell membrane. The scores for VEGF stained cells were moderately positive (++) on day 10, strongly positive (+++) on day 44. Ki-67-positive hepatocytes reached at 65% on day 10, at 65.78% on day 14, at 66.4% on day 30, at 67.88% on day 44. Conclusion: AX7 cells implanted into liver can be used as a new rabbit metastatic liver carcinoma model and would become useful for human metastatic liver carcinoma studies. Future studies may facilitate the establishment of an effective systemic therapy for the metastatic liver cancer.

Hemocoagulase Combined with Microbubble-Enhanced Ultrasound Cavitation for Augmented Ablation of Microvasculature in Rabbit VX2 Liver Tumors

We investigated a new method for combining microbubble-enhanced ultrasound cavitation (MEUC) with hemocoagulase (HC) atrox. Our goal was to induce embolic effects in the vasculature and combine these with an anti-angiogenic treatment strategy. Fourteen days after being implanted with a single slice of the liver VX2 tumor, rabbits were randomly divided into five groups: (i) a control group injected intra-venously with saline using a micropump; (ii) a group given only an injection of HC; (iii) a group treated only with ultrasound cavitation; (iv) a group treated with MEUC; (v) a group treated with MEUC + HC. Contrast-enhanced ultrasound was performed before treatment and 1 h and 7 d post-treatment to measure tumor size, enhancement and necrosis range. QontraXt software was used to determine the time-intensity curve of tumor blood perfusion and microvascular changes. At 1 h and 7 d after treatment with MEUC + HC, the parameters of the time-intensity curve, which included peak value, regional blood volume, regional blood flow and area under the curve value and which were measured using contrast-enhanced ultrasound, were significantly lower than those of the other treatment groups. The MEUC + HC treatment group exhibited significant growth inhibition relative to the ultrasound cavitation only, HC and MEUC treatment groups. No damage was observed in the surrounding normal tissues. These results support the feasibility of reducing the blood perfusion of rabbit VX2 liver tumors using a new method that combines MEUC and HC.

Modified transarterial chemoembolization with locoregional administration of sorafenib for treating hepatocellular carcinoma: feasibility, efficacy, and safety in the VX-2 rabbit liver tumor model

PURPOSE

We aimed to assess the feasibility, efficacy and safety of a local application of sorafenib within a conventional transarterial chemoembolization in the VX-2 tumor-bearing rabbit model.

METHODS

VX-2 tumors were induced in the left liver lobe of 10 New Zealand White rabbits. After two weeks, growth was verified by contrast-enhanced computed tomography (CT). Five rabbits were treated by transarterial chemoembolization using an emulsion of sorafenib and ethiodized oil (referred to as SORATACE; n=5). Rabbits receiving oral sorafenib for two weeks (n=2) and untreated rabbits (n=3) served as controls. After two weeks, contrast-enhanced CT was performed, followed by animal necropsy.

RESULTS

The change in tumor diameter between baseline and follow-up was significantly different in the SORATACE group compared with the other groups; tumor shrinkage was observed in the SORATACE group only (P = 0.016). In both control groups, preserved hypervascularity was seen in the follow-up CT in all but one tumor. All tumors in the SORATACE group were devascularized in the follow-up CT. Importantly, substantial parenchymal damage in nontargeted areas of the tumor-bearing liver lobe was seen in rabbits treated with SORATACE.

CONCLUSION

SORATACE demonstrated high efficacy in the treatment of experimental VX-2 liver tumors but was also associated with substantial liver parenchymal toxicity.

Establishment of human metastatic colorectal cancer model in rabbit liver: A pilot study

Rationale and objectives

To develop a human metastatic colorectal cancer (mCRC) model in a rabbit liver.

Materials and methods

Immunosuppression in 4 adult New Zealand White rabbits weighing 3.5 to 4.5 kg was induced with daily subcutaneous injection of 15 mg/kg Cyclosporine A (CsA). On day 3 open mini-laparotomy was performed and 0.2 ml (1.8x10⁵ cells) suspension of HCT-116 and HT-29 human CRC cells were injected into the left and right medial lobe respectively. On day 10 the CsA dose was reduced to 10 mg/kg daily maintenance dose. Rabbits were weighed weekly, closely monitored for CsA side effects (weight loss, gingival hyperplasia and gut modification). Rabbits were sacrificed 5, 6, 7, and 8 weeks after cells injection. Liver tumors were collected for histopathology and immunohistochemical analysis.

Results

HT-29 Tumor growth was observed in 3 rabbits (75%). Tumors measured 3, 4 and 6 mm after 5, 6 and 8 weeks respectively. Microscopically, tumors contained hyperchromatic, pleomorphic cells that stained for monoclonal carcinoembryonic antigen (CEA), polyclonal CEA, cytokeratin 20, vascular markers (CD31, CD34), and vascular endothelial growth factor (VEGF) by immunohistochemistry, supporting involvement by the poorly differentiated HT-29 colorectal cancer cell line. No gross tumor growth or microscopic viability was observed from HCT-116 cell injection. CsA extra-hepatic manifestations included minimal gum hyperplasia and decrease in gut motility in 3 rabbits (75%), which was treated with Azithromycin 15 mg/kg and Cisapride 0.5 mg/kg every 12 hours, respectively.

Conclusion

We successfully developed a human metastatic colon cancer model in immunosuppressed rabbit liver using HT-29 cells.

Percutaneous ultrasound guided implantation of VX2 for creation of a rabbit hepatic tumor model

Creation of a VX2 tumor model has traditionally required a laparotomy and surgical implantation of tumor fragments. Open surgical procedures are invasive and require long procedure times and recovery that can result in post-operative morbidity and mortality. The purpose of this study is to report the results of a percutaneous ultrasound guided method for creation of a VX2 model in rabbit livers. A total of 27 New Zealand white rabbits underwent a percutaneous ultrasound guided approach, where a VX2 tumor fragment was implanted in the liver. Magnetic resonance imaging was used to assess for tumor growth and necropsy was performed to determine rates of tract seeding and metastatic disease. Ultrasound guided tumor implantation was successful in all 27 rabbits. One rabbit died 2 days following the implantation procedure. Two rabbits had no tumors seen on follow-up imaging. Therefore, tumor development was seen in 24/26 (92%) rabbits. During the follow-up period, tract seeding was seen in 8% of rabbits and 38% had extra-hepatic metastatic disease. Therefore, percutaneous ultrasound guided tumor implantation safely provides reliable tumor growth for establishing hepatic VX2 tumors in a rabbit model with decreased rates of tract seeding, compared to previously reported methods.

Early treatment response to sorafenib for rabbit VX2 orthotic liver tumors: evaluation by quantitative contrast-enhanced ultrasound

The aim of our study was to investigate the application of contrast-enhanced ultrasound (CEUS) and its quantification analysis for the prediction of early treatment response of sorafenib on rabbit VX2 liver tumor model. Rabbits were implanted VX2 tumor mass to establish a liver tumor model. Fourteen days after tumor implantation, rabbits presented with single liver tumor were randomly divided into two groups. Rabbits in treatment group were given by gavage once a day for 14 days with sorafenib suspension at a dose of 30 mg/kg, whereas rabbits in control group were given saline by gavage of the same volume. CEUS was performed before treatment and 3, 7, 14 days after treatment for the analysis of tumor size, enhancement pattern, and necrosis range. The time intensity curve (TIC) was used to obtain quantitative parameters of enhancement patterns. Before sorafenib administration, tumor volumes ranged from 0.24 to 0.75 cm(3) (mean 0.49 ± 0.18 cm(3)) in treatment group and 0.24 to 0.44 cm(3) (mean 0.30 ± 0.12 cm(3)) in control group. The dynamic enhancement patterns of tumors were homogeneous hyper-enhancement (n = 8), heterogeneous hyper-enhancement (n = 4), and peripheral rim-like enhancement (n = 2). All tumors of the treatment group presented with peripheral rim-like enhancement with large necrotic area after sorafenib administration, whereas tumors of the control group showed heterogeneous hyper-enhancement (n = 5) and peripheral rim-like enhancement (n = 2). There was a significant difference in area under the curve (AUC) before and after sorafenib treatment (P = 0.045). CEUS may be of value in the evaluation of early therapeutic response after sorafenib administration.

Dynamical observation on biological progression of VX2 liver tumors to identify the optimal time for intervention in animal models

Purpose

Based on practice guideline of “management of hepatocellular carcinoma (HCC): update” published by American Association for the Study of Liver Diseases (AASLD) and “Barcelona Clinic Liver Cancer staging system (BCLC),” this study investigated how to enroll the optimal VX2 liver tumor model for HCC researches by dynamically observing the biological progression of the tumor.

Materials

Thirty-two healthy New Zealand white rabbits were implanted VX2 liver tumor by cell suspension method (n=24) and tissue fragment method (n=8). All the rabbits underwent CT scans on day 7, 14, 21 and 28 after implantation to observe the size of the tumors, the time when metastases and ascites occurred and the survival time. Appropriate intervention times were estimated corresponding to different clinical HCC stages by using tumor diameter-time curve.

Results

The VX2 liver tumors grew rapidly within 28 days after implantation. And the tumors in the cell suspension group grew faster than those of the tissue fragment group. The appropriate intervention time corresponding to very early stage, early stage and intermediate stage were <11 days, 11–16.9 days and >16.9 days, respectively in the cell suspension group, and <19.9 days, 19.9–25.5 days and >25.5 days, respectively in the tissue fragment group.

Conclusion

Preclinical animal research needs to improve on different levels to yield best predictions for human patients. Researchers should seek for an individualized proposal to select optimal VX2 liver tumor models for their experiments. This approach may lead to a more accurate determination of therapeutic outcomes.

Multifunctional doxorubicin loaded superparamagnetic iron oxide nanoparticles for chemotherapy and magnetic resonance imaging in liver cancer

To develop a drug delivery system with enhanced efficacy and minimized adverse effects, we synthesized a novel polymeric nanoparticles, (YCC-DOX) composed of poly (ethylene oxide)-trimellitic anhydride chloride-folate (PEO-TMA-FA), doxorubicin (DOX) and superparamagnetic iron oxide (Fe(3)O(4)) and folate. The efficacy of the nanoparticles was evaluated in rats and rabbits with liver cancer, in comparison with free-DOX (FD) and a commercial liposome drug, DOXIL. YCC-DOX showed the anticancer efficacy and specifically targeted folate receptor (FR)-expressing tumors, thereby increasing the bioavailability and efficacy of DOX. The relative tumor volume of the YCC-DOX group was decreased two- and four-fold compared with the FD and DOXIL groups in the rat and rabbit models, respectively. Furthermore, YCC-DOX showed higher MRI sensitivity comparable to a conventional MRI contrast agent (Resovist), even in its lower iron content. In the immunohistochemical analysis, YCC-DOX group showed the lower expression of CD34 and Ki-67, markers of angiogenesis and cell proliferation, respectively, while apoptotic cells were significantly rich in the YCC-DOX group in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. These results indicate that YCC-DOX is a promising candidate for treating liver cancer and monitoring the progress of the cancer using MRI.

Role of sonography for implantation and sequential evaluation of a VX2 rabbit liver tumor model

OBJECTIVE

We investigated the role of sonography in the implantation process of a VX2 rabbit liver tumor model and sequential evaluation.

METHODS

Fifty rabbits were divided into 2 groups. Animals in group I underwent surgical implantation, whereas those in group II received percutaneous sonographically guided implantation. At 7, 14, 21, and 28 days after implantation, respectively, 5 rabbits in each group were examined with conventional, color Doppler (CD), contrast-enhanced (CE) pulse inversion harmonic (PIH), and CE CD sonography. Pathologic examination was performed with hematoxylin-eosin, nicotinamide adenine dinucleotide phosphate-diaphorase, and succinic dehydrogenase stains.

RESULTS

Twenty-one rabbits with tumors survived in group I, and 22 with tumors survived in group II. The mean duration of implantation +/- SD in group II was 16.9 +/- 3.4 minutes, whereas that in group I was 21.5 +/- 4.1 minutes (P < .05). The tumor volume measured by conventional sonography increased from 0.28 +/- 0.14 cm(3) at 7 days to 16.49 +/- 5.50 cm(3) at 28 days in group I and from 0.31 +/- 0.19 to 19.79 +/- 4.70 cm(3) in group II, whereas no significant difference existed between the groups. On CD, CE PIH, and CE CD sonography, most tumors were hypervascular before 14 days and after 14 days had peripheral vessels and central hypovascular areas, which were shown as necrotic areas by pathologic examination.

CONCLUSIONS

Sonographically guided implantation achieved a good success rate with convenient inoculation performance. Conventional gray scale, CD, CE PIH, and CE CD sonography were useful in sequential evaluation of tumor growth and characteristic vascularity.

Considerations for implantation site of VX2 carcinoma into rabbit liver

PURPOSE

To assess whether the implantation site of VX2 carcinoma into rabbit liver affects successful vessel selection for transcatheter arterial interventions.

MATERIALS AND METHODS

Twenty-four New Zealand White rabbits were randomly assigned to two groups. All implantations were performed by open laparotomy with minced tumor cells inserted into a 16-gauge Angiocath needle. Group I rabbits (n = 12) had tumor implanted into the left medial lobe of the liver and group II rabbits (n = 12) had tumor implanted into the left lateral lobe. Two weeks after implantation, selective angiography was performed for subsequent chemoembolization, which was part of a different study. Tested variables included maximum tumor diameter, tumor feeding artery size, and tumor vascularity.

RESULTS

Successful tumor growth was achieved in all rabbits. Selective angiography was possible in 33.3% of rabbits in group I and 66.6% of rabbits in group II (P < .05). Tumor size and vascularity were similar between groups. Mean lengths of tumor feeder arteries from the bifurcation of the left hepatic artery were 4.1 mm +/- 1.2 in group I (left medial lobe) and 10.8 mm +/- 3.0 in group II (left lateral lobe; P < .05). The angulation of the left medial lobar artery (group I) off the left hepatic artery was acute in eight of 12 rabbits (66.6%), but only four of 12 rabbits in group II (33.3%) showed acute angulation of the left lateral lobar artery off the left hepatic artery (P < .05). Mean angiography time was significantly shorter in group II.

CONCLUSIONS

For selective hepatic arterial interventions, the left lateral lobe of the liver may be favorable as an implantation site for VX2 tumors in rabbits.

Percutaneous US-guided implantation of Vx-2 carcinoma into rabbit liver: a comparison with open surgical method

PURPOSE

To evaluate technical feasibility and experimental usefulness of percutaneous US-guided implantation of Vx-2 carcinoma in rabbit liver.

MATERIALS AND METHODS

Forty-eight New Zealand White male rabbits were used. Solid tumor mass of Vx-2 carcinoma was harvested from carrier rabbit, and minced tumor cells were implanted. Twenty-four rabbits underwent percutaneous US-guided tumor implantation, and the same number of rabbits underwent open laparotomy tumor implantation. Tested parameters included technical success, procedural time, amount of anesthesia, recovery time, complications, tumor size, and regional tumor seeding.

RESULTS

A new percutaneous US-guided implantation was technically feasible in all rabbits. Evaluation parameters showed that the percutaneous US-guided implantation method is less invasive than the open laparotomy method. Targeting rate for left lateral lobe of implantation site was comparable in both methods (91.7% of percutaneous US-guided; 95.8% in open laparotomy). The success rate of tumor growth in the liver was 100% in both groups. However, in the group with US-guidance, tumor seeding developed more frequently in five of 24 rabbits (20.8%) than in open laparotomy group (2/24, 8.3%). Five rabbits had thoracoabdominal wall needle tract seeding, and two rabbits had tumor seeding at both thoracoabdominal wall and intraperitoneal space.

CONCLUSIONS

Percutaneous US-guided implantation of Vx-2 carcinoma in rabbit liver is a less invasive alternative to open laparotomy, achieving equally successful tumor growth in the liver. Although percutaneous US-guidance implantation method may not be considered for long-term survival study design because of the possibility of tumor seeding, it can be considered for nonsurvival study design.

Comparison of two different methods for inoculating VX2 tumors in rabbit livers and hind limbs

PURPOSE

To compare two methods to (a) propagate VX2 cell strain in rabbit hind limbs and (b) inoculate liver parenchymal tumors in rabbits.

MATERIALS AND METHODS

One hundred forty-two New Zealand white rabbits were used for this study (60 with hind limb tumor [donors] and 82 with liver tumors [recipients]). In the donor group, nine rabbits received frozen VX2 cell suspension and 51 were injected with freshly prepared VX2 cell suspension. In the recipient group, 32 rabbits were injected with VX2 tumor cells and 50 were implanted with a small tumor fragment in the liver parenchyma. Success rates in terms of tumor growth were compared by using chi(2) or Fisher exact tests, with alpha = .05.

RESULTS

Hind limb and liver tumors were successfully grown in 48 of the 60 rabbits in the donor group (80%) and 57 of the 82 rabbits in the recipient group (70%). The success rate of growing hind limb tumors increased from 33% (three of nine rabbits) to 88% (45 of 51 rabbits) when fresh VX2 cells instead of frozen were injected percutaneously (P < .0011). Similarly, the success rate for VX2 liver tumors almost doubled from 47% (15 of 32 rabbits) to 84% (42 of 50 rabbits) when a tumor fragment instead of VX2 cell suspension was used (P < .00036). This also significantly reduced the frequency of metastasis (P < .005).

CONCLUSIONS

The authors recommend (a) the use of fresh VX2 cell suspension for percutaneous injection in the hind limbs of rabbits to maintain the VX2 cell strain and (b) the surgical implantation of freshly harvested VX2 tumor fragment into the liver parenchyma to establish liver tumors.

Cell apoptosis and regeneration of hepatocellular carcinoma after transarterial chemoembolization

AIM: To evaluate whether cell apoptosis and regeneration were existed in normal liver cells adjacent to carcinoma after transarterial chemoembolization (TACE).

METHODS: Fifty rabbits with hepatic carcinoma were divided into 5 groups at random: group A (control group), groups B and C (TACE treatment groups), groups D and E (partial hepatectomy groups). There were 10 rabbits in each group. Rabbits in groups B-E were treated by transarterial chemoembolization (TACE) and partial hepatectomy (PH) respectively. The changes of S-phase cell fraction (SPF), proliferation index (PI) and cell apoptosis in the normal liver tissue were determined with flow cytometry (FCM) after operations on the first and third days. We determined the mitosis index (MI) with histo-pathological method and the apoptosis index (AI) with TUNEL method at the same time.

RESULTS: Twenty-four hours after operations, compared with control group, the rabbits in TACE group had much higher index of SPF, PI and MI (MI: t = 4.89, P < 0.001; SPF: t = 5.27, P < 0.001; PI: t = 4.87, P < 0.001). Moreover, the proliferation of liver cells in TACE group was much weaker than that of the cells treated by partial hepatectomy, and the differences were significant (MI: t = 7.02, P < 0.001; SPF: t = 4.06, P < 0.001; PI: t = 2.70, P < 0.05). Seventy-two h after operations, FCM showed a small sub-G1 peak in TACE group and PH group, compared with the control group, but there was no difference between them (t = 0.41, P > 0.05). TACE showed that AI in the treated rabbits was higher than that in control group (t = 3.07, P < 0.05), and there were no differences between TACE group and PH group, either (t = 0.93, P > 0.05).

CONCLUSION: Cell apoptosis and regeneration exist in rabbit liver tissues after TACE in some degree, which may be associated with the selective embolization of iodised oil, chemotherapeutic drug and free radical damage.