Transplantation of cancerous cell sheets effectively generates tumour-bearing model mice

The generation and use of animal models of osteosarcoma in cancer research

Osteosarcoma is the most common malignant bone tumor affecting children and adolescents. Currently, the most common treatment is surgery combined with neoadjuvant chemotherapy. Although the survival rate of patients with osteosarcoma has improved in recent years, it remains poor when the tumor(s) progress and distant metastases develop. Therefore, better animal models that more accurately replicate the natural progression of the disease are needed to develop improved prognostic and diagnostic markers, as well as targeted therapies for both primary and metastatic osteosarcoma. The present review described animal models currently being used in research investigating osteosarcoma, and their characteristics, advantages, and disadvantages. These models may help elucidate the pathogenic mechanism(s) of osteosarcoma and provide evidence to support and develop clinical treatment strategies.

Establishment and evaluation of ectopic and orthotopic prostate cancer models using cell sheet technology

Background

The traditional prostate cancer (PCa) model is established by injecting cell suspension and is associated with a low tumor formation rate. Cell sheet technology is one of the advancements in tissue engineering for 3D cell-based therapy. In this study, we established ectopic and orthotopic PCa models by cell sheet technology, and then compared the efficiency of tumor formation with cell suspension injection.

Methods

DU145 cells were seeded on 35 mm temperature-sensitive dishes to form PCa cell sheets, while the cell suspension with the same cell density was prepared. After transplanting into the nude mice, the tumor volumes were measured every 3 days and the tumor growth curves were conducted. At the time points of 2 weeks and 4 weeks after the transplantation, magnetic resonance imaging (MRI) was used to evaluate the transplanting site and distant metastasis. Finally, the mice were sacrificed, and the related tissues were harvested for the further histological evaluation.

Results

The orthotopic tumor formation rate of the cell sheet injection group was obviously better than that in cell suspension injection group (100% vs 67%). Compared with cell suspension injection, the tumors of DU145 cell sheet fragments injection had the higher density of micro-vessels, more collagen deposition, and lower apoptosis rate. There was no evidence of metastasis in forelimb, lung and liver was found by MRI and histological tests.

Conclusion

We successfully cultured the DU145 cell sheet and can be used to establish ectopic and orthotopic PCa tumor-bearing models, which provide an application potential for preclinical drug development, drug-resistance mechanisms and patient individualized therapy.

Hot or cold: Bioengineering immune contextures into in vitro patient-derived tumor models

In the past decade, immune checkpoint inhibitors (ICI) have proven to be tremendously effective for a subset of cancer patients. However, it is difficult to predict the response of individual patients and efforts are now directed at understanding the mechanisms of ICI resistance. Current models of patient tumors poorly recapitulate the immune contexture, which describe immune parameters that are associated with patient survival. In this Review, we discuss parameters that influence the induction of different immune contextures found within tumors and how engineering strategies may be leveraged to recapitulate these contextures to develop the next generation of immune-competent patient-derived in vitro models.

Fundamental Technologies and Recent Advances of Cell-Sheet-Based Tissue Engineering

Tissue engineering has attracted significant attention since the 1980s, and the applications of tissue engineering have been expanding. To produce a cell-dense tissue, cell sheet technology has been studied as a promising strategy. Fundamental techniques involving tissue engineering are mainly introduced in this review. First, the technologies to fabricate a cell sheet were reviewed. Although temperature-responsive polymer-based technique was a trigger to establish and spread cell sheet technology, other methodologies for cell sheet fabrication have also been reported. Second, the methods to improve the function of the cell sheet were investigated. Adding electrical and mechanical stimulation on muscle-type cells, building 3D structures, and co-culturing with other cell species can be possible strategies for imitating the physiological situation under in vitro conditions, resulting in improved functions. Finally, culture methods to promote vasculogenesis in the layered cell sheets were introduced with in vivo, ex vivo, and in vitro bioreactors. We believe the present review that shows and compares the fundamental technologies and recent advances for cell-sheet-based tissue engineering should promote further development of tissue engineering. The development of cell sheet technology should promote many bioengineering applications.

A novel rat model of inflammatory bowel disease developed using a device created with a 3D printer

Objective

Inflammatory bowel disease (IBD) is an intractable condition. Existing models of experimental IBD are limited by their inability to create consistent ulcers between animals. The aim of this study was to develop a novel model of experimental colitis with ulcers of reproducible size.

Design

We used a 3D printer to fabricate a novel device containing a small window (10 × 10 mm) that could be inserted rectally to facilitate the creation of a localized ulcer in the rat intestinal mucosa. The mucosa within the window of the device was exposed to 2,4,6-trinitrobenzene sulfonic acid (TNBS) to generate ulceration. We evaluated the effects of conventional drug therapies (mesalazine and prednisolone) and local transplantation of allogeneic adipose-derived mesenchymal stem cells (ASCs) on ulcer size (measured from photographic images using image analysis software) and degree of inflammation (assessed histologically).

Results

The novel method produced localized, circular or elliptical ulcers that were highly reproducible in terms of size and depth. The pathological characteristics of the lesions were similar to those reported previously for conventional models of TNBS-induced colitis that show greater variation in ulcer size. Ulcer area was significantly reduced by the administration of mesalazine or prednisolone as an enema or localized injection of ASCs.

Conclusion

The new model of TNBS-induced colitis, made with the aid of a device fabricated by 3D printing, generated ulcers that were reproducible in size. We anticipate that our new model of colitis will provide more reliable measures of treatment effects and prove useful in future studies of IBD therapies.

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Adipose-derived stem cells (ASCs) are being explored as a new treatment for IBD because they can downregulate inflammation and improve tissue repair.

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A new model of TNBS-induced colitis was developed using a custom-designed device fabricated by a 3D printer.

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The novel model of colitis generated ulcers that were highly reproducible in size.

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The size of the ulcer was reduced by mesalazine or prednisolone (administered as an enema) or by localized injection of ASCs.

Efficient intrahepatic tumor generation by cell sheet transplantation to fabricate orthotopic hepatocarcinoma-bearing model mice for drug testing

Subcutaneous tumor-bearing mice are commonly used to evaluate antitumor activity in preclinical studies of anticancer drugs. However, these models often exhibit excessive antitumor responses to anticancer drug candidates. In this study, intrahepatic tumor-bearing mice as orthotopic tumor models were fabricated by transplanting hepatocarcinoma cell monolayers (sheets) to investigate differences in ectopic versus orthotopic antitumor response. Cell sheets, harvested from temperature-responsive cell culture dishes using thin gelatin gel supporters, were transferred onto mouse liver surfaces. Cell sheet transplantation drastically improved intrahepatic tumor formation compared with direct intrahepatic injection of dispersed cells. In particular, all cell sheet-transplanted mice formed well-developed tumors inside the liver following removal of the mesothelial membrane at the liver surface. Notably, these mice exhibited comparable life spans, indicating similar intrahepatic tumor development rates. Antitumor activity of doxorubicin (DOX) was examined using both subcutaneous and intrahepatic tumor-bearing mice. Although DOX administration yielded decreased subcutaneous tumor volumes, intrahepatic tumors exhibited no significant antitumor response. The results were considered to represent pharmacokinetic and histological structure differences between ectopic and orthotopic tumors, and partially supported the clinical uses of DOX. Therefore, cancer cell sheet transplantation constitutes a promising method to fabricate intrahepatic tumor-bearing mice for drug screening test in preclinical studies. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1071-1079, 2019.

Vascularized Tissue-Engineered Model for Studying Drug Resistance in Neuroblastoma

Neuroblastoma is a vascularized pediatric tumor derived from neural crest stem cells that displays vasculogenic mimicry and can express a number of stemness markers, such as SOX2 and NANOG. Tumor relapse is the major cause of succumbing to this disease, and properties attributed to cancer stem-like cells (CSLC), such as drug-resistance and cell plasticity, seem to be the key mechanisms. However, the lack of controllable models that recapitulate the features of human neuroblastoma limits our understanding of the process and impedes the development of new therapies. In response to these limitations, we engineered a perfusable, vascularized in vitro model of three-dimensional human neuroblastoma to study the effects of retinoid therapy on tumor vasculature and drug-resistance.

METHODS

The in vitro model of neuroblastoma was generated using cell-sheet engineering and cultured in a perfusion bioreactor. Firstly, we stacked three cell sheets containing SKNBE(2) neuroblastoma cells and HUVEC. Then, a vascular bed made of fibrin, collagen I and HUVEC cells was placed onto a collagen-gel base with 8 microchannels. After gelling, the stacked cell sheets were placed on the vascular bed and cultured in the perfusion bioreactor (perfusion rate: 0.5 mL/min) for 4 days. Neuroblastoma models were treated with 10μM isotretionin in single daily doses for 5 days.

RESULTS

The bioengineered model recapitulated vasculogenic mimicry (vessel-like structure formation and tumor-derived endothelial cells-TECs), and contained CSLC expressing SOX2 and NANOG. Treatment with Isotretinoin destabilized vascular networks but failed to target vasculogenic mimicry and augmented populations of CSLCs expressing high levels of SOX2. Our results suggest that CSLCs can transdifferentiate into drug resistant CD31⁺-TECs, and reveal the presence of an intermediate state STEC (stem tumor-derived endothelial cell) expressing both SOX2 and CD31.

CONCLUSION

Our results reveal some roles of SOX2 in drug resistance and tumor relapse, and suggest that SOX2 could be a therapeutic target in neuroblastoma.

Progress in Corneal Stromal Repair: From Tissue Grafts and Biomaterials to Modular Supramolecular Tissue-Like Assemblies

Corneal injuries and degenerative conditions have major socioeconomic consequences, given that in most cases, they result in blindness. In the quest of the ideal therapy, tissue grafts, biomaterials, and modular engineering approaches are under intense investigation. Herein, advancements and shortfalls are reviewed and future perspectives for these therapeutic strategies discussed.

Tissue-engineered models of human tumors for cancer research

INTRODUCTION

Drug toxicity often goes undetected until clinical trials, which are the most costly and dangerous phase of drug development. Both the cultures of human cells and animal studies have limitations that cannot be overcome by incremental improvements in drug-testing protocols. A new generation of bioengineered tumors is now emerging in response to these limitations, with potential to transform drug screening by providing predictive models of tumors within their tissue context, for studies of drug safety and efficacy. An area that could greatly benefit from these models is cancer research.

AREAS COVERED

In this review, the authors first describe the engineered tumor systems, using Ewing's sarcoma as an example of human tumor that cannot be predictably studied in cell culture and animal models. Then, they discuss the importance of the tissue context for cancer progression and outline the biomimetic principles for engineering human tumors. Finally, they discuss the utility of bioengineered tumor models for cancer research and address the challenges in modeling human tumors for use in drug discovery and testing.

EXPERT OPINION

While tissue models are just emerging as a new tool for cancer drug discovery, they are already demonstrating potential for recapitulating, in vitro, the native behavior of human tumors. Still, numerous challenges need to be addressed before we can have platforms with a predictive power appropriate for the pharmaceutical industry. Some of the key needs include the incorporation of the vascular compartment, immune system components, and mechanical signals that regulate tumor development and function.

Modeling human carcinomas: physiologically relevant 3D models to improve anti-cancer drug development

Anti-cancer drug development is inefficient, mostly due to lack of efficacy in human patients. The high fail rate is partly due to the lack of predictive models or the inadequate use of existing preclinical test systems. However, progress has been made and preclinical models were improved or newly developed, which all account for basic features of solid cancers, three-dimensionality and heterotypic cell interaction. Here we give an overview of available in vivo and in vitro models of cancer, which meet the criteria of being 3D and mirroring human tumor-stroma interactions. We only focus on drug response models without touching models for pharmacokinetic and dynamic, toxicity or delivery aspects.