Description of an intraperitoneal tumour xenograft survival model in the pig

Establishment of a piglet model for peritoneal metastasis of ovarian cancer

Background

A piglet model for peritoneal metastasis (PM) of ovarian cancer was developed. It will contribute to establishing innovative chemotherapeutical and surgical strategies without any limitation on rodent models.

Methods

A total of 12 four- to five-week-old piglets of 7 to 8 kg were used. Two phases of ovarian cancer cell injections were performed with laparoscopic surgery.

In phase I trial, 5.0 × 10⁶ SK-OV-3 cells in 0.1 ml suspension were inoculated into the omentum, peritoneum, and uterine horns of two piglets twice with a one-week interval. In the phase II trial, 5.0 × 10⁶ SNU-008 cells in 0.1 ml suspension were injected only into uterine horns within the same time frame because tumor implantation after inoculation of SK-OV-3 cells was not observed at the omentum or peritoneum in the phase I trial. Modified peritoneal cancer index (PCI) score was used to monitor tumorigenesis up to 4 weeks after inoculation. Tumor tissues disseminated in the peritoneum 4 weeks after injection were used for histological examination with hematoxylin and eosin (H&E) and paired-box gene 8 (PAX-8) staining.

Results

In the phase I trial, two piglets showed PM with modified PCI scores of 5 and 4 at 3 weeks after the first inoculation, which increased to 14 and 15 after 4 weeks, respectively. In the phase II trial, PM was detected in eight of ten piglets, which showed modified PCI scores of 6 to 12 at 4 weeks after the first inoculation. The overall incidence of PM from the total of 12 piglets after inoculation was 75%. Immunohistochemical H&E and PAX-8 staining confirmed metastatic tumors.

Conclusions

This study provides strong evidence that piglets can be employed as a model for PM by inoculating ovarian cancer cell lines from humans. Using two cell lines, the PM rate is 75%.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03533-1.

Preclinical In Vivo-Models to Investigate HIPEC; Current Methodologies and Challenges

Simple Summary

Efficacy of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) depends on patient selection, tumor type, delivery technique, and treatment parameters such as temperature, carrier solution, type of drug, dosage, volume, and treatment duration. Preclinical research offers a powerful tool to investigate the impact of these parameters and to assists in designing potentially more effective treatment protocols and clinical trials. This study aims to review the objectives, methods, and clinical relevance of in vivo preclinical HIPEC studies found in the literature. In total, 60 articles were included in this study. The selected articles were screened on the HIPEC parameters. Recommendations are provided and possible pitfalls are discussed on the choice of type of animal and tumor model per stratified parameters and study goal. The guidelines presented in this paper can improve the clinical relevance and impact of future in vivo HIPEC experiments.

Abstract

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment modality for patients with peritoneal metastasis (PM) of various origins which aims for cure in combination with cytoreductive surgery (CRS). Efficacy of CRS-HIPEC depends on patient selection, tumor type, delivery technique, and treatment parameters such as temperature, carrier solution, type of drug, dosage, volume, and treatment duration. Preclinical research offers a powerful tool to investigate the impact of these parameters and to assist in designing potentially more effective treatment protocols and clinical trials. The different methodologies for peritoneal disease and HIPEC are variable. This study aims to review the objectives, methods, and clinical relevance of in vivo preclinical HIPEC studies found in the literature. In this review, recommendations are provided and possible pitfalls are discussed on the choice of type of animal and tumor model per stratified parameters and study goal. The guidelines presented in this paper can improve the clinical relevance and impact of future in vivo HIPEC experiments.

Non-murine models to investigate tumor-immune interactions in head and neck cancer

The immune response has important roles in the biology of solid tumors, including oncogenesis, tumor growth, invasion and metastasis, and response to treatment. Improved understanding of tumor-immune system interactions has provided promising therapeutic options that are based on the rescue and enhancement of the anti-tumoral host response. Immune-based treatments have been approved for clinical use in various types of cancer, including head and neck cancer (HNC); other strategies involving combination therapies are currently in development. These novel therapies were developed based on knowledge derived from in vitro, in silico, and in vivo pre-clinical studies. However, clinical trials seldom replicate the efficacy observed in pre-clinical animal studies. This lack of correlation between pre-clinical studies and clinical trials may be related to limitations of the models used; which highlights the relevance of considering immune-related aspects of different pre-clinical models. Murine models are the most frequently used pre-clinical models of HNC and are discussed elsewhere. Non-murine models have characteristics that offer unique opportunities for the study of HNC etiology, therapeutic strategies, and tumor-immune system interactions. The current review focuses on immune-related aspects of non-murine models, including dog, cat, pig, zebrafish, and frog, that could be used to investigate tumor-immune interactions in HNC.

Generation of a TP53-modified porcine cancer model by CRISPR/Cas9-mediated gene modification in porcine zygotes via electroporation

TP53 (which encodes p53) is one of the most frequently mutated genes in cancers. In this study, we generated TP53-mutant pigs by gene editing via electroporation of the Cas9 protein (GEEP), a process that involves introducing the Cas9 protein and single-guide RNA (sgRNA) targeting exon 3 and intron 4 of TP53 into in vitro-fertilized zygotes. Zygotes modified by the sgRNAs were transferred to recipients, two of which gave birth to a total of 11 piglets. Of those 11 piglets, 9 survived. Molecular genetic analysis confirmed that 6 of 9 live piglets carried mutations in TP53, including 2 piglets with no wild-type (WT) sequences and 4 genetically mosaic piglets with WT sequences. One mosaic piglet had 142 and 151 bp deletions caused by a combination of the two sgRNAs. These piglets were continually monitored for 16 months and three of the genome-edited pigs (50%) exhibited various tumor phenotypes that we presumed were caused by TP53 mutations. Two mutant pigs with no WT sequences developed mandibular osteosarcoma and nephroblastoma. The mosaic pig with a deletion between targeting sites of two sgRNAs exhibited malignant fibrous histiocytoma. Tumor phenotypes of TP53 mosaic mutant pigs have not been previously reported. Our results indicated that the mutations caused by gene editing successfully induced tumor phenotypes in both TP53 mosaic- and bi-allelic mutant pigs.

Tumor cell dissemination during laparoscopy: prevention and therapeutic opportunities

Port-site recurrences (PSRs) are abdominal wall recurrences that occur in the subcutaneous tissue within a trocar site after cancer laparoscopy and are not associated with peritoneal carcinomatosis. In order to develop PSRs, viable tumor cells must be liberated from the primary tumor, be transported to a wound, and find there a favorable environment for growth. The short clinical delay in the occurrence of PSRs and their size suggest massive cell seeding into the abdominal wall. Traumatic handling of the tumor, slipping of trocars, liquid projection, as well as poor extraction techniques can all cause implantation of malignant cells into the subcutaneous tissue. Such contact can also occur postoperatively if the trocar channels remain open. Some histologies (e.g. gallbladder adenocarcinoma), the presence of ascites and advanced tumor stage are risk factors for PSRs. Further conditions--including the use of gas--might also play a limited role. The first preventive measure is the correct indication for a laparoscopic approach. Several techniques have been demonstrated to prevent PSRs in the animal model: (a) fixation of trocars to the abdominal wall; (b) prevention of leakage; (c) careful specimen handling; (d) reducing trauma to the abdominal wall; (e) specimen isolation before extraction from the abdominal cavity; (f) trocar-site irrigation with a cytotoxic solution, and (g) closure of peritoneum. Further innovative therapies are currently under investigation. In the clinical setting, correct indication, surgical expertise and application of prophylactic measures seem to be the best way to prevent the occurrence of PSRs.

Efficacy of surgical measures in preventing port-site recurrences in a porcine model

BACKGROUND

Port-site recurrences are serious complications of laparoscopy performed for cancer. Incidences reported in the literature vary between 0% and 21%, suggesting an influence of the surgeon.

METHODS

The aim of this experimental, prospective, randomized, single-blind study was to investigate the influence that the quality surgery has on the incidence of port-site recurrences. After a 12-mmHg carbon dioxide (CO2) pneumoperitoneum was created, 10(7) human HeLa cell were injected into the peritoneal cavity of 18 pigs, creating a xenogeneic tumor. Laparoscopic sigmoid resections then were performed using four trocars and a transanal double-stapling technique. The following protective measures were applied in nine animals: trocar fixation, prevention of gas leaks, rinsing of instruments with povidone-iodine, minilaparotomy protection, rinsing of trocars before removal, peritoneal closure, and rinsing of all wounds with povidoneiodine. Surgeons and type of procedures were randomized. After 4 weeks, the animals were killed and all portsites excised. Blinded immunohistologic analysis with antihuman pancytokeratin antibody was performed.

RESULTS

Tumor recurrence was present in 23 of 36 port sites (63.8%) in the control group, but only in 5 of 36 port sites (13.8%) in the group that received protective measures (p = 0.002; Fisher's exact test). No peritoneal carcinosis nor anastomotic recurrences were observed.

CONCLUSION

These results strongly suggest that the quality of surgical technique has an influence on the incidence of port-site recurrences. From now on, we propose to use these protective measures routinely in cancer laparoscopy.