In vitro ovarian cancer model based on three-dimensional agarose hydrogel

Development of a hydrogel-based three-dimensional (3D) glioblastoma cell lines culture as a model system for CD73 inhibitor response study

BACKGROUND

Despite the development of various therapeutic approaches over the past decades, the treatment of glioblastoma multiforme (GBM) remains a major challenge. The extracellular adenosine-generating enzyme, CD73, is involved in the pathogenesis and progression of GBM, and targeting CD73 may represent a novel approach to treat this cancer. In this study, three-dimensional culture systems based on three hydrogel compositions were characterized and an optimal type was selected to simulate the GBM microenvironment. In addition, the effect of a CD73 inhibitor on GBM cell aggregates and spheroids was investigated as a potential therapeutic approach for this disease.

METHODS

Rheology measurements, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and cell proliferation assays were performed to analyze the synthesized hydrogel and select an optimal formulation. The viability of tumor cells in the optimal hydrogel was examined histologically and by confocal microscopy. In addition, the sensitivity of the tumor cells to the CD73 inhibitor was investigated using a cell proliferation assay and real-time PCR.

RESULTS

The data showed that the hydrogel containing 5 wt% gelatin and 5 wt% sodium alginate had better rheological properties and higher cell viability. Therefore, it could provide a more suitable environment for GBM cells and better mimic the natural microenvironment. GBM cells treated with CD73 inhibitors significantly decreased the proliferation rate and expression of VEGF and HIF1-α in the optimal hydrogel.

CONCLUSION

Our current research demonstrates the great potential of CD73 inhibitor for clinical translation of cancer studies by analyzing the behavior and function of 3D tumor cells, and thus for more effective treatment protocols for GBM.

Nanocomposite Hydrogel Bioinks for 3D Bioprinting of Tumor Models

In vitro tumor models were successfully constructed by 3D bioprinting; however, bioinks with proper viscosity, good biocompatibility, and tunable biophysical and biochemical properties are highly desirable for tumor models that closely recapitulated the main features of native tumors. Here, we developed a nanocomposite hydrogel bioink that was used to construct ovarian and colon cancer models by 3D bioprinting. The nanocomposite bioink was composed of aldehyde-modified cellulose nanocrystals (aCNCs), aldehyde-modified hyaluronic acid (aHA), and gelatin. The hydrogels possessed tunable gelation time, mechanical properties, and printability by controlling the ratio between aCNCs and gelatin. In addition, ovarian and colorectal cancer cells embedded in hydrogels showed high survival rates and rapid growth. By the combination of 3D bioprinting, ovarian and colorectal tumor models were constructed in vitro and used for drug screening. The results showed that gemcitabine had therapeutic effects on ovarian tumor cells. However, the ovarian tumor model showed drug resistance for oxaliplatin treatment.

Recent advances in 3D bioprinted tumor models for personalized medicine

Cancerous tumors are among the most fatal diseases worldwide, claiming nearly 10 million lives in 2020. Due to their complex and dynamic nature, modeling tumors accurately is a challenging task. Current models suffer from inadequate translation between in vitro and in vivo results, primarily due to the isotropic nature of tumors and their microenvironment's relationship. To address these limitations, hydrogel-based 3D bioprinting is emerging as a promising approach to mimic cancer development and behavior. It provides precise control over individual elements' size and distribution within the cancer microenvironment and enables the use of patient-derived tumor cells, rather than commercial lines. Consequently, hydrogel bioprinting is expected to become a state-of-the-art technique for cancer research. This manuscript presents an overview of cancer statistics, current modeling methods, and their limitations. Additionally, we highlight the significance of bioprinting, its applications in cancer modeling, and the importance of hydrogel selection. We further explore the current state of creating models for the five deadliest cancers using 3D bioprinting. Finally, we discuss current trends and future perspectives on the clinical use of cancer modeling using hydrogel bioprinting.

Scaffold Using Chitosan, Agarose, Cellulose, Dextran and Protein for Tissue Engineering-A Review

Biological macromolecules like polysaccharides/proteins/glycoproteins have been widely used in the field of tissue engineering due to their ability to mimic the extracellular matrix of tissue. In addition to this, these macromolecules are found to have higher biocompatibility and no/lesser toxicity when compared to synthetic polymers. In recent years, scaffolds made up of proteins, polysaccharides, or glycoproteins have been highly used due to their tensile strength, biodegradability, and flexibility. This review is about the fabrication methods and applications of scaffolds made using various biological macromolecules, including polysaccharides like chitosan, agarose, cellulose, and dextran and proteins like soy proteins, zein proteins, etc. Biopolymer-based nanocomposite production and its application and limitations are also discussed in this review. This review also emphasizes the importance of using natural polymers rather than synthetic ones for developing scaffolds, as natural polymers have unique properties, like high biocompatibility, biodegradability, accessibility, stability, absence of toxicity, and low cost.

The Development of a Three-Dimensional Platform for Patient-Derived Ovarian Cancer Tissue Models: A Systematic Literature Review

There is an unmet biomedical need for ex vivo tumour models that would predict drug responses and in turn help determine treatment regimens and potentially predict resistance before clinical studies. Research has shown that three dimensional models of ovarian cancer (OvCa) are more realistic than two dimensional in vitro systems as they are able to capture patient in vivo conditions in more accurate manner. The vast majority of studies aiming to recapitulate the ovarian tumour morphology, behaviors, and study chemotherapy responses have been using ovarian cancer cell lines. However, despite the advantages of utilising cancer cell lines to set up a platform, they are not as informative as systems applying patient derived cells, as cell lines are not able to recapitulate differences between each individual patient characteristics. In this review we discussed the most recent advances in the creation of 3D ovarian cancer models that have used patient derived material, the challenges to overcome and future applications.

Injectable three-dimensional tumor microenvironments to study mechanobiology in ovarian cancer

Epithelial ovarian cancers are among the most aggressive forms of gynecological malignancies. Despite the advent of poly adenosine diphosphate-ribose polymerase (PARP) and checkpoint inhibitors, improvement to patient survival has been modest. Limited in part by clinical translation, beneficial therapeutic strategies remain elusive in ovarian cancers. Although elevated levels of extracellular proteins, including collagens, proteoglycans, and glycoproteins, have been linked to chemoresistance, they are often missing from the processes of drug- development and screening. Biophysical and biochemical signaling from the extracellular matrix (ECM) determine cellular phenotype and affect both tumor progression and therapeutic response. However, many state-of-the-art tumor models fail to mimic the complexities of the tumor microenvironment (TME) and omit key signaling components. In this article, two interpenetrating network (IPN) hydrogel scaffold platforms, comprising of alginate-collagen or agarose-collagen, have been characterized for use as 3D in vitro models of epithelial ovarian cancer ECM. These highly tunable, injection mold compatible, and inexpensive IPNs replicate the critical governing physical and chemical signaling present within the ovarian TME. Additionally, an effective and cell-friendly live-cell retrieval method has been established to recover cells post-encapsulation. Lastly, functional mechanotransduction in ovarian cancers was demonstrated by increasing scaffold stiffness within the 3D in vitro ECM models. With these features, the agarose-collagen and alginate-collagen hydrogels provide a robust TME for the study of mechanobiology in epithelial cancers. STATEMENT OF SIGNIFICANCE: Ovarian cancer is the most lethal gynecologic cancer afflicting women today. Here we present the development, characterization, and validation of 3D interpenetrating platforms to shift the paradigm in standard in vitro modeling. These models help elucidate the roles of biophysical and biochemical cues in ovarian cancer progression. The agarose-collagen and alginate-collagen interpenetrating network (IPN) hydrogels are simple to fabricate, inexpensive, and can be modified to create custom mechanical stiffnesses and concentrations of bio-adhesive motifs. Given that investigations into the roles of biophysical characteristics in ovarian cancers have provided incongruent results, we believe that the IPN platforms will be critically important to uncovering molecular drivers. We also expect these platforms to be broadly applicable to studies involving mechanobiology in solid tumors.

Polymeric Hydrogels for In Vitro 3D Ovarian Cancer Modeling

Ovarian cancer (OC) grows and interacts constantly with a complex microenvironment, in which immune cells, fibroblasts, blood vessels, signal molecules and the extracellular matrix (ECM) coexist. This heterogeneous environment provides structural and biochemical support to the surrounding cells and undergoes constant and dynamic remodeling that actively promotes tumor initiation, progression, and metastasis. Despite the fact that traditional 2D cell culture systems have led to relevant medical advances in cancer research, 3D cell culture models could open new possibilities for the development of an in vitro tumor microenvironment more closely reproducing that observed in vivo. The implementation of materials science and technology into cancer research has enabled significant progress in the study of cancer progression and drug screening, through the development of polymeric scaffold-based 3D models closely recapitulating the physiopathological features of native tumor tissue. This article provides an overview of state-of-the-art in vitro tumor models with a particular focus on 3D OC cell culture in pre-clinical studies. The most representative OC models described in the literature are presented with a focus on hydrogel-based scaffolds, which guarantee soft tissue-like physical properties as well as a suitable 3D microenvironment for cell growth. Hydrogel-forming polymers of either natural or synthetic origin investigated in this context are described by highlighting their source of extraction, physical-chemical properties, and application for 3D ovarian cancer cell culture.

A Systematic Comparative Assessment of the Response of Ovarian Cancer Cells to the Chemotherapeutic Cisplatin in 3D Models of Various Structural and Biochemical Configurations-Does One Model Type Fit All?

Epithelial Ovarian Cancer (EOC) is a silent, deadly and aggressive gynaecological disease with a relatively low survival rate. This has been attributed, to some extent, to EOC's high recurrence rate and resistance to currently available platinum-based chemotherapeutic treatment methods. Multiple groups have studied and reported the effect of chemotherapeutic agents on various EOC 3D in vitro models. However, there are very few studies wherein a direct comparative study has been carried out between the different in vitro 3D models of EOC and the effect of chemotherapy within them. Herein, we report, for the first time, a direct comprehensive systematic comparative study of three different 3D in vitro platforms, namely (i) spheroids, (ii) synthetic PeptiGels/hydrogels of various chemical configurations and (iii) polymeric scaffolds with coatings of various extracellular matrices (ECMs) on the cell growth and response to the chemotherapeutic (Cisplatin) for ovary-derived (A2780) and metastatic (SK-OV-3) EOC cell lines. We report that all three 3D models are able to support the growth of EOC, but for different time periods (varying from 7 days to 4 weeks). We have also reported that chemoresistance to Cisplatin, in vitro, observed especially for metastatic EOC cells, is platform-dependent, in terms of both the structural and biochemical composition of the model/platform. Our study highlights the importance of selecting an appropriate 3D platform for in vitro tumour model development. We have demonstrated that the selection of the best platform for producing in vitro tumour models depends on the cancer/cell type, the experimental time period and the application for which the model is intended.

Three-Dimensional Modelling of Ovarian Cancer: From Cell Lines to Organoids for Discovery and Personalized Medicine

Ovarian cancer has the highest mortality of all of the gynecological malignancies. There are several distinct histotypes of this malignancy characterized by specific molecular events and clinical behavior. These histotypes have differing responses to platinum-based drugs that have been the mainstay of therapy for ovarian cancer for decades. For histotypes that initially respond to a chemotherapeutic regime of carboplatin and paclitaxel such as high-grade serous ovarian cancer, the development of chemoresistance is common and underpins incurable disease. Recent discoveries have led to the clinical use of PARP (poly ADP ribose polymerase) inhibitors for ovarian cancers defective in homologous recombination repair, as well as the anti-angiogenic bevacizumab. While predictive molecular testing involving identification of a genomic scar and/or the presence of germline or somatic BRCA1 or BRCA2 mutation are in clinical use to inform the likely success of a PARP inhibitor, no similar tests are available to identify women likely to respond to bevacizumab. Functional tests to predict patient response to any drug are, in fact, essentially absent from clinical care. New drugs are needed to treat ovarian cancer. In this review, we discuss applications to address the currently unmet need of developing physiologically relevant in vitro and ex vivo models of ovarian cancer for fundamental discovery science, and personalized medicine approaches. Traditional two-dimensional (2D) in vitro cell culture of ovarian cancer lacks critical cell-to-cell interactions afforded by culture in three-dimensions. Additionally, modelling interactions with the tumor microenvironment, including the surface of organs in the peritoneal cavity that support metastatic growth of ovarian cancer, will improve the power of these models. Being able to reliably grow primary tumoroid cultures of ovarian cancer will improve the ability to recapitulate tumor heterogeneity. Three-dimensional (3D) modelling systems, from cell lines to organoid or tumoroid cultures, represent enhanced starting points from which improved translational outcomes for women with ovarian cancer will emerge.

Personalized models of heterogeneous 3D epithelial tumor microenvironments: Ovarian cancer as a model

Intractable human diseases such as cancers, are context dependent, unique to both the individual patient and to the specific tumor microenvironment. However, conventional cancer treatments are often nonspecific, targeting global similarities rather than unique drivers. This limits treatment efficacy across heterogeneous patient populations and even at different tumor locations within the same patient. Ultimately, this poor efficacy can lead to adverse clinical outcomes and the development of treatment-resistant relapse. To prevent this and improve outcomes, it is necessary to be selective when choosing a patient's optimal adjuvant treatment. In this review, we posit the use of personalized, tumor-specific models (TSM) as tools to achieve this remarkable feat. First, using ovarian cancer as a model disease, we outline the heterogeneity and complexity of both the cellular and extracellular components in the tumor microenvironment. Then we examine the advantages and disadvantages of contemporary cancer models and the rationale for personalized TSM. We discuss how to generate precision 3D models through careful and detailed analysis of patient biopsies. Finally, we provide clinically relevant applications of these versatile personalized cancer models to highlight their potential impact. These models are ideal for a myriad of fundamental cancer biology and translational studies. Importantly, these approaches can be extended to other carcinomas, facilitating the discovery of new therapeutics that more effectively target the unique aspects of each individual patient's TME. STATEMENT OF SIGNIFICANCE: In this article, we have presented the case for the application of biomaterials in developing personalized models of complex diseases such as cancers. TSM could bring about breakthroughs in the promise of precision medicine. The critical components of the diverse tumor microenvironments, that lead to treatment failures, include cellular- and extracellular matrix- heterogeneity, and biophysical signals to the cells. Therefore, we have described these dynamic components of the tumor microenvironments, and have highlighted how contemporary biomaterials can be utilized to create personalized in vitro models of cancers. We have also described the application of the TSM to predict the dynamic patterns of disease progression, and predict effective therapies that can produce durable responses, limit relapses, and treat any minimal residual disease.

Cancer Cell Direct Bioprinting: A Focused Review

Three-dimensional printing technologies allow for the fabrication of complex parts with accurate geometry and less production time. When applied to biomedical applications, two different approaches, known as direct or indirect bioprinting, may be performed. The classical way is to print a support structure, the scaffold, and then culture the cells. Due to the low efficiency of this method, direct bioprinting has been proposed, with or without the use of scaffolds. Scaffolds are the most common technology to culture cells, but bioassembly of cells may be an interesting methodology to mimic the native microenvironment, the extracellular matrix, where the cells interact between themselves. The purpose of this review is to give an updated report about the materials, the bioprinting technologies, and the cells used in cancer research for breast, brain, lung, liver, reproductive, gastric, skin, and bladder associated cancers, to help the development of possible treatments to lower the mortality rates, increasing the effectiveness of guided therapies. This work introduces direct bioprinting to be considered as a key factor above the main tissue engineering technologies.

Surface modification of neurotrophin-3 loaded PCL/chitosan nanofiber/net by alginate hydrogel microlayer for enhanced biocompatibility in neural tissue engineering

This study prepared a novel three-dimensional nanocomposite scaffold by the surface modification of PCL/chitosan nanofiber/net with alginate hydrogel microlayer, hoping to have the privilege of both nanofibers and hydrogels simultaneously. Bead free randomly oriented nanofiber/net (NFN) structure composed of chitosan and polycaprolactone (PCL) was fabricated by electrospinning method. The low surface roughness, good hydrophilicity, and high porosity were obtained from the NFN structure. Then, the PCL/chitosan nanofiber/net was coated with a microlayer of alginate containing neurotrophin-3 (NT-3) and conjunctiva mesenchymal stem cells (CJMSCs) as a new stem cell source. According to the cross-sectional FESEM, the scaffold shows a two-layer structure with interconnected pores in the range of 20 μm diameter. The finding revealed that the surface modification of nanofiber/net by alginate hydrogel microlayer caused lower inflammatory response and higher proliferation of CJMSCs than the unmodified scaffold. The initial burst release of NT-3 was 69% in 3 days which followed by a sustained release up to 21 days. The RT-PCR analysis showed that the expression of Nestin, MAP-2, and β-tubulin III genes were increased 6, 5.4, and 8.8-fold, respectively. The results revealed that the surface-modified biomimetic scaffold possesses enhanced biocompatibility and could successfully differentiate CJMSCs to the neuron-like cells.

Development of a stacked, porous silk scaffold neuroblastoma model for investigating spatial differences in cell and drug responsiveness

Development of in vitro, preclinical cancer models that contain cell-driven microenvironments remains a challenge. Engineering of millimeter-scale, in vitro tumor models with spatially distinct regions that can be independently assessed to study tumor microenvironments has been limited. Here, we report the use of porous silk scaffolds to generate a high cell density neuroblastoma (NB) model that can spatially recapitulate changes resulting from cell and diffusion driven changes. Using COMSOL modeling, a scaffold holder design that facilitates stacking of thin, 200 μm silk scaffolds into a thick, bulk millimeter-scale tumor model (2, 4, 6, and 8 stacked scaffolds) and supports cell-driven oxygen gradients was developed. Cell-driven oxygen gradients were confirmed through pimonidazole staining. Post-culture, the stacked scaffolds were separated for analysis on a layer-by-layer basis. The analysis of each scaffold layer demonstrated decreasing DNA and increasing expression of hypoxia related genes (VEGF, CAIX, and GLUT1) from the exterior scaffolds to the interior scaffolds. Furthermore, the expression of hypoxia related genes at the interior of the stacks was comparable to that of a single scaffold cultured under 1% O₂ and at the exterior of the stacks was comparable to that of a single scaffold cultured under 21% O₂. The four-stack scaffold model underwent further evaluation to determine if a hypoxia activated drug, tirapazamine, induced reduced cell viability within the internal stacks (region of reduced oxygen) as compared with the external stacks. Decreased DNA content was observed in the internal stacks as compared to the external stacks when treated with tirapazamine, which suggests the internal scaffold stacks had higher levels of hypoxia than the external scaffolds. This stacked silk scaffold system presents a method for creating a single culture model capable of generating controllable cell-driven microenvironments through different stacks that can be individually assessed and used for drug screening.

Engineered 3D tumour model for study of glioblastoma aggressiveness and drug evaluation on a detachably assembled microfluidic device

3D models of tumours have emerged as an advanced technique in pharmacology and tumour cell biology, in particular for studying malignant tumours such as glioblastoma multiforme (GBM). Herein, we developed a 3D GBM model on a detachably assembled microfluidic device, which could be used to study GBM aggressiveness and for anti-GBM drug testing. Fundamental characteristics of the GBM microenvironment in terms of 3D tissue organisation, extracellular matrices and blood flow were reproduced in vitro by serial manipulations in the integrated microfluidic device, including GBM spheroid self-assembly, embedding in a collagen matrix, and continuous perfusion culture, respectively. We could realize multiple spheroids parallel manipulation, whilst, compartmentalized culture, in a highly flexible manner. This method facilitated investigations into the viability, proliferation, invasiveness and phenotype transition of GBM in a 3D microenvironment and under continuous stimulation by drugs. Anti-invasion effect of resveratrol, a naturally isolated polyphenol, was innovatively evaluated using this in vitro 3D GBM model. Temozolomide and the combination of resveratrol and temozolomide were also evaluated as control. This scalable model enables research into GBM in a more physiologically relevant microenvironment, which renders it promising for use in translational or personalised medicine to examine the impact of, or identify combinations of, therapeutic agents.

Alteration of microRNA profiling in sphere-cultured ovarian carcinoma cells

Ovarian cancer is an aggressive and lethal cancer, which in part, can be attributed to complications in the effective detection of this disease during early stages of progression. Frequently, epithelial ovarian cancer is disseminated to the abdominal cavity and forms multicellular aggregates. This unique early metastatic event, and formation of the multicellular aggregate is implicated to provide a basis for understanding the underlying molecular mechanisms of metastasis in ovarian cancer. Therefore, a 3-dimensional (3D) sphere culture system was established in the present study to mimic the later stages of ovarian cancer. The aim of the present study was to investigate whether microRNAs (miRNAs), which have functions in metastasis and chemoresistance in various cancer models, are altered in ovarian cancer cells by 3-dimensional (3D) culture. A multicellular aggregate of SKOV3ip1 ovarian carcinoma cells was generated using a 3D sphere culture system. Cell viability analysis demonstrated that the sphere-cultured SKOV3ip1 cells exhibited chemoresistance compared with those in a conventional 2-dimensional (2D) monolayer cultured SKOV3ip1 system. Under the same experimental conditions, 71 upregulated miRNAs and 63 downregulated miRNAs were identified in the 3D sphere-cultured SKOV3ip1 cells. The predicted targets of the 3D sphere-culture specific miRNAs were further identified using PITA, microRNAorg and TargetScan. Compared with the target gene pool and Kyoto Encyclopedia of Genes and Genomes pathway, the present study provides evidence that the 3D sphere culture-specific miRNAs regulated sphere formation and chemoresistance in 3D sphere-cultured SKOV3ip1 cells. Overall, the results of the present study demonstrated that miRNA-mediated regulation is implicated to provoke features of SKOV3ip1 multicellular aggregation, including sphere formation and chemoresistance.

Micropassage-embedding composite hydrogel fibers enable quantitative evaluation of cancer cell invasion under 3D coculture conditions

Cell migration and invasion are of significant importance in physiological phenomena, including wound healing and cancer metastasis. Here we propose a new system for quantitatively evaluating cancer cell invasion in a three-dimensional (3D), in vivo tissue-like environment. This system uses composite hydrogel microfibers whose cross section has a relatively soft micropassage region and that were prepared using a multilayered microfluidic device; cancer cells are encapsulated in the core and fibroblasts are seeded in the shell regions surrounding the core. Cancer cell proliferation is guided through the micropassage because of the physical restriction imposed by the surrounding solid shell regions. Quantitative analysis of cancer cell invasion is possible simply by counting the cancer cell colonies that form outside the fiber. This platform enables the evaluation of anticancer drug efficacy (cisplatin, paclitaxel, and 5-fluorouracil) based on the degree of invasion and the gene expression of cancer cells (A549 cells) with or without the presence of fibroblasts (NIH-3T3 cells). The presented hydrogel fiber-based migration assays could be useful for studying cell behaviors under 3D coculture conditions and for drug screening and evaluation.

Evaluating Biomaterial- and Microfluidic-Based 3D Tumor Models

Cancer is a major cause of morbidity and mortality worldwide, with a disease burden estimated to increase over the coming decades. Disease heterogeneity and limited information on cancer biology and disease mechanisms are aspects that 2D cell cultures fail to address. Here, we review the current ‘state-of-the-art’ in 3D tissue-engineering (TE) models developed for, and used in, cancer research. We assess the potential for scaffold-based TE models and microfluidics to fill the gap between 2D models and clinical application. We also discuss recent advances in combining the principles of 3D TE models and microfluidics, with a special focus on biomaterials and the most promising chip-based 3D models.

Alginate–marine collagen–agarose composite hydrogels as matrices for biomimetic 3D cell spheroid formation

We report a novel, customizable, transparent, biocompatible, functional, easy-to-produce, efficient and cost-effective AmCA scaffold for 3D cell culture.

Studying platinum sensitivity and resistance in high-grade serous ovarian cancer: Different models for different questions

High-grade serous ovarian cancer (HGSOC) has the highest mortality rate among all gynecological cancers. Patients are generally diagnosed in an advanced stage with the majority of cases displaying platinum resistant relapses. Recent genomic interrogation of large numbers of HGSOC patient samples indicated high complexity in terms of genetic aberrations, intra- and intertumor heterogeneity and underscored their lack of targetable oncogenic mutations. Sub-classifications of HGSOC based on expression profiles, termed 'differentiated', 'immunoreactive', 'mesenchymal' and 'proliferative', were shown to have prognostic value. In addition, in almost half of all HGSOC patients, a deficiency in homologous recombination (HR) was found that potentially can be targeted using PARP inhibitors. Developing precision medicine requires advanced experimental models. In the current review, we discuss experimental HGSOC models in which resistance to platinum therapy and the use of novel therapeutics can be carefully studied. Panels of better-defined primary cell lines need to be established to capture the full spectrum of HGSOC subtypes. Further refinement of cell lines is obtained with a 3-dimensional culture model mimicking the tumor microenvironment. Alternatively, ex vivo ovarian tumor tissue slices are used. For in vivo studies, larger panels of ovarian cancer patient-derived xenografts (PDXs) are being established, encompassing all expression subtypes. Ovarian cancer PDXs grossly retain tumor heterogeneity and clinical response to platinum therapy is preserved. PDXs are currently used in drug screens and as avatars for patient response. The role of the immune system in tumor responses can be assessed using humanized PDXs and immunocompetent genetically engineered mouse models. Dynamic tracking of genetic alterations in PDXs as well as patients during treatment and after relapse is feasible by sequencing circulating cell-free tumor DNA and analyzing circulating tumor cells. We discuss how various models and methods can be combined to delineate the molecular mechanisms underlying platinum resistance and to select HGSOC patients other than BRCA1/2-mutation carriers that could potentially benefit from the synthetic lethality of PARP inhibitors. This integrated approach is a first step to improve therapy outcomes in specific subgroups of HGSOC patients.

Enhanced radiation therapy with multilayer microdisks containing radiosensitizing gold nanoparticles

A challenge of X-ray radiation therapy is that high dose X-rays at therapeutic conditions damage normal cells. This paper describes the use of gold nanoparticle-loaded multilayer microdisks to enhance X-ray radiation therapy, where each microdisk contains over 10(5) radiosensitizing nanoparticles. The microdisks are attached on cell membranes through electrostatic interaction. Upon X-ray irradiation, more photoelectrons and Auger electrons are generated in the vicinity of the nanoparticles, which cause water ionization and lead to the formation of free radicals that damage the DNA of adjacent cancer cells. By attaching a large amount of gold nanoparticles on cancer cells, the total X-ray dose required for DNA damage and cell killing can be reduced. Due to their controllable structure and composition, multilayer microdisks can be a viable choice for enhanced radiation therapy with nanoparticles.