Three-dimensional (3D) culture in sarcoma research and the clinical significance

Feasibility and barriers to rapid establishment of patient-derived primary osteosarcoma cell lines in clinical management

Osteosarcoma is a highly aggressive primary bone tumor that has seen little improvement in survival rates in the past three decades. Preclinical studies are conducted on a small pool of commercial cell lines which may not fully reflect the genetic heterogeneity of this complex cancer, potentially hindering translatability of in vitro results. Developing a single-site laboratory protocol to rapidly establish patient-derived primary cancer cell lines (PCCL) within a clinically actionable time frame of a few weeks will have significant scientific and clinical ramifications. These PCCL can widen the pool of available cell lines for study while patient-specific data could derive therapeutic correlation. This endeavor is exceedingly challenging considering the proposed time constraints. By proposing key definitions and a clear theoretical framework, this evaluation of osteosarcoma cell line establishment methodology over the past three decades assesses feasibility by identifying barriers and suggesting solutions, thereby facilitating systematic experimentation and optimization.

Toward morphologically relevant extracellular matrix: nanofiber-hydrogel composites for tumor cell culture

The natural extracellular matrix (ECM) consists of a continuous integrated fibrin network and a negatively charged proteoglycan-based matrix. In this work, we report a novel three-dimensional nanofiber hydrogel composite that mimics the natural ECM structure, exhibiting both degradability and mechanical characteristics comparable to that of tumor tissue. The embedded nanofiber improves the hydrogel mechanical properties, and varying the fiber density can match the elastic modulus of different tumor tissues (1.51-10.77 kPa). The degradability of the scaffold gives sufficient space for tumor cells to secrete and remodel the ECM. The expression levels of cancer stem cell markers confirmed the development of aggressive and metastatic phenotypes of prostate cancer cells in the 3D scaffold. Similar results were obtained in terms of anticancer resistance of prostate cancer cells in 3D scaffolds showing stem cell-like properties, suggesting that the current bionic 3D scaffold tumor model has broad potential in the development of effective targeted agents.

Enhanced Biomimetics of Three-Dimensional Osteosarcoma Models: A Scoping Review

This scoping review evaluated 3D osteosarcoma (OS) models' biomimicry, examining their ability to mimic the tumour microenvironment (TME) and their drug sensitivity. Adhering to PRISMA-ScR guidelines, the systematic search revealed 293 studies, with 70 selected for final analysis. Overall, 64% of 3D OS models were scaffold-based, compared to self-generated spheroid models. Scaffolds generated using native matrix were most common (42%) with collagen I/hydroxyapatite predominating. Both scaffold-based and scaffold-free models were used equally for drug screening. The sensitivity of cancer cells in 3D was reported to be lower than that of cells in 2D in ~90% of the drug screening studies. This correlates with the observed upregulation of drug resistance. OS cells cultured in extracellular matrix (ECM)-mimetic scaffolds and native biomaterials were more resistant than cells in 2D. Co-cultures of OS and stromal cells in 3D models enhanced osteogenic differentiation, ECM remodelling, mineralisation, and angiogenesis, suggesting that tumour-stroma crosstalk promotes disease progression. Seven studies demonstrated selective toxicity of chemotherapeutics towards OS cells while sparing stromal cells, providing useful evidence for developing biomimetic tumour-stroma models to test selective drug toxicity. In conclusion, this review highlights the need to enhance biomimicry in 3D OS models for TME recapitulation, especially in testing novel therapeutics. Future research should explore innovative 3D biomimetic models, biomaterials, and advancements in personalised medicine.

Exploring the promising potential of induced pluripotent stem cells in cancer research and therapy

The advent of iPSCs has brought about a significant transformation in stem cell research, opening up promising avenues for advancing cancer treatment. The formation of cancer is a multifaceted process influenced by genetic, epigenetic, and environmental factors. iPSCs offer a distinctive platform for investigating the origin of cancer, paving the way for novel approaches to cancer treatment, drug testing, and tailored medical interventions. This review article will provide an overview of the science behind iPSCs, the current limitations and challenges in iPSC-based cancer therapy, the ethical and social implications, and the comparative analysis with other stem cell types for cancer treatment. The article will also discuss the applications of iPSCs in tumorigenesis, the future of iPSCs in tumorigenesis research, and highlight successful case studies utilizing iPSCs in tumorigenesis research. The conclusion will summarize the advancements made in iPSC-based tumorigenesis research and the importance of continued investment in iPSC research to unlock the full potential of these cells.

Preclinical Models of Visceral Sarcomas

Visceral sarcomas are a rare malignant subgroup of soft tissue sarcomas (STSs). STSs, accounting for 1% of all adult tumors, are derived from mesenchymal tissues and exhibit a wide heterogeneity. Their rarity and the high number of histotypes hinder the understanding of tumor development mechanisms and negatively influence clinical outcomes and treatment approaches. Although some STSs (~20%) have identifiable genetic markers, as specific mutations or translocations, most are characterized by complex genomic profiles. Thus, identification of new therapeutic targets and development of personalized therapies are urgent clinical needs. Although cell lines are useful for preclinical investigations, more reliable preclinical models are required to develop and test new potential therapies. Here, we provide an overview of the available in vitro and in vivo models of visceral sarcomas, whose gene signatures are still not well characterized, to highlight current challenges and provide insights for future studies.

Photon and Proton irradiation in Patient-derived, Three-Dimensional Soft Tissue Sarcoma Models

BACKGROUND

Despite their heterogeneity, the current standard preoperative radiotherapy regimen for localized high-grade soft tissue sarcoma (STS) follows a one fits all approach for all STS subtypes. Sarcoma patient-derived three-dimensional cell culture models represent an innovative tool to overcome challenges in clinical research enabling reproducible subtype-specific research on STS. In this pilot study, we present our methodology and preliminary results using STS patient-derived 3D cell cultures that were exposed to different doses of photon and proton radiation. Our aim was: (i) to establish a reproducible method for irradiation of STS patient-derived 3D cell cultures and (ii) to explore the differences in tumor cell viability of two different STS subtypes exposed to increasing doses of photon and proton radiation at different time points.

METHODS

Two patient-derived cell cultures of untreated localized high-grade STS (an undifferentiated pleomorphic sarcoma (UPS) and a pleomorphic liposarcoma (PLS)) were exposed to a single fraction of photon or proton irradiation using doses of 0 Gy (sham irradiation), 2 Gy, 4 Gy, 8 Gy and 16 Gy. Cell viability was measured and compared to sham irradiation at two different time points (four and eight days after irradiation).

RESULTS

The proportion of viable tumor cells four days after photon irradiation for UPS vs. PLS were significantly different with 85% vs. 65% (4 Gy), 80% vs. 50% (8 Gy) and 70% vs. 35% (16 Gy). Proton irradiation led to similar diverging viability curves between UPS vs. PLS four days after irradiation with 90% vs. 75% (4 Gy), 85% vs. 45% (8 Gy) and 80% vs. 35% (16 Gy). Photon and proton radiation displayed only minor differences in cell-killing properties within each cell culture (UPS and PLS). The cell-killing effect of radiation sustained at eight days after irradiation in both cell cultures.

CONCLUSIONS

Pronounced differences in radiosensitivity are evident among UPS and PLS 3D patient-derived sarcoma cell cultures which may reflect the clinical heterogeneity. Photon and proton radiation showed similar dose-dependent cell-killing effectiveness in both 3D cell cultures. Patient-derived 3D STS cell cultures may represent a valuable tool to enable translational studies towards individualized subtype-specific radiotherapy in patients with STS.

A perfusion-based three-dimensional cell culture system to model alveolar rhabdomyosarcoma pathological features

Although a rare disease, rhabdomyosarcoma (RMS) is one of the most common cancers in children the more aggressive and metastatic subtype is the alveolar RMS (ARMS). Survival outcomes with metastatic disease remain dismal and the need for new models that recapitulate key pathological features, including cell-extracellular matrix (ECM) interactions, is warranted. Here, we report an organotypic model that captures cellular and molecular determinants of invasive ARMS. We cultured the ARMS cell line RH30 on a collagen sponge in a perfusion-based bioreactor (U-CUP), obtaining after 7 days a 3D construct with homogeneous cell distribution. Compared to static culture, perfusion flow induced higher cell proliferation rates (20% vs. 5%), enhanced secretion of active MMP-2, and upregulation of the Rho pathway, associated with cancer cell dissemination. Consistently, the ECM genes LAMA1 and LAMA2, the antiapoptotic gene HSP90, identified in patient databases as hallmarks of invasive ARMS, were higher under perfusion flow at mRNA and protein level. Our advanced ARMS organotypic model mimics (1) the interactions cells-ECM, (2) the cell growth maintenance, and (3) the expression of proteins that characterize tumor expansion and aggressiveness. In the future, the perfusion-based model could be used with primary patient-derived cell subtypes to create a personalized ARMS chemotherapy screening system.

Chitosan Cryogels Cross-Linked with 1,1,3-Triglycidyloxypropane: Mechanical Properties and Cytotoxicity for Cancer Cell 3D Cultures

Here, we have presented a new method of 1,1,3-triglycidyloxypropane (TGP) synthesis and investigated how cross-linker branching affects mechanical properties and cytotoxicity of chitosan scaffolds in comparison with those cross-linked using diglycidyl ethers of 1,4-butandiol (BDDGE) and poly(ethylene glycol) (PEGDGE). We have demonstrated that TGP is an efficient cross-linker for chitosan at a subzero temperature at TGP:chitosan molar ratios from 1:1 to 1:20. Although the elasticity of chitosan scaffolds increased in the following order of the cross-linkers PEGDGE > TGP > BDDGE, TGP provided cryogels with the highest compressive strength. Chitosan-TGP cryogels have shown low cytotoxicity for colorectal cancer HCT 116 cell line and supported the formation of 3D multicellular structures of the spherical shape and size up to 200 µm, while in more brittle chitosan-BDDGE cryogel this cell culture formed epithelia-like sheets. Hence, the selection of the cross-linker type and concentration for chitosan scaffold fabrication can be used to mimic the solid tumor microenvironment of certain human tissue, control matrix-driven changes in the morphology of cancer cell aggregates, and facilitate long-term experiments with 3D tumor cell cultures.

Bone-on-a-Chip: Biomimetic Models Based on Microfluidic Technologies for Biomedical Applications

With the increasing importance of preclinical evaluation of newly developed drugs or treatments, in vitro organ or disease models are necessary. Although various organ-specific on-chip (organ-on-a-chip, or OOC) systems have been developed as emerging in vitro models, bone-on-a-chip (BOC) systems that recapitulate the bone microenvironment have been less developed or reviewed compared with other OOCs. The bone is one of the most dynamic organs and undergoes continuous remodeling throughout its lifetime. The aging population is growing worldwide, and healthcare costs are rising rapidly. Since in vitro BOC models that recapitulate native bone niches and pathological features can be important for studying the underlying mechanism of orthopedic diseases and predicting drug responses in preclinical trials instead of in animals, the development of biomimetic BOCs with high efficiency and fidelity will be accelerated further. Here, we review recently engineered BOCs developed using various microfluidic technologies and investigate their use to model the bone microenvironment. We have also explored various biomimetic strategies based on biological, geometrical, and biomechanical cues for biomedical applications of BOCs. Finally, we addressed the limitations and challenging issues of current BOCs that should be overcome to obtain more acceptable BOCs in the biomedical and pharmaceutical industries.

Newly developed 3D in vitro models to study tumor-immune interaction

Immunotherapy as a rapidly developing therapeutic approach has revolutionized cancer treatment and revitalized the field of tumor immunology research. 3D in vitro models are emerging as powerful tools considering their feature to maintain tumor cells in a near-native state and have been widely applied in oncology research. The novel 3D culture methods including the co-culture of organoids and immune cells, ALI culture, 3D-microfluidic culture and 3D-bioprinting offer new approaches for tumor immunology study and can be applied in many fields such as personalized treatment, immunotherapy optimizing and adoptive cell therapy. In this review, we introduce commonly used 3D in vitro models and summarize their applications in different aspects of tumor immunology research. We also provide a preliminary analysis of the current shortcomings of these models and the outlook of future development.

The emerging role of cancer nanotechnology in the panorama of sarcoma

In the field of nanomedicine a multitude of nanovectors have been developed for cancer application. In this regard, a less exploited target is represented by connective tissue. Sarcoma lesions encompass a wide range of rare entities of mesenchymal origin affecting connective tissues. The extraordinary diversity and rarity of these mesenchymal tumors is reflected in their classification, grading and management which are still challenging. Although they include more than 70 histologic subtypes, the first line-treatment for advanced and metastatic sarcoma has remained unchanged in the last fifty years, excluding specific histotypes in which targeted therapy has emerged. The role of chemotherapy has not been completely elucidated and the outcomes are still very limited. At the beginning of the century, nano-sized particles clinically approved for other solid lesions were tested in these neoplasms but the results were anecdotal and the clinical benefit was not substantial. Recently, a new nanosystem formulation NBTXR3 for the treatment of sarcoma has landed in a phase 2-3 trial. The preliminary results are encouraging and could open new avenues for research in nanotechnology. This review provides an update on the recent advancements in the field of nanomedicine for sarcoma. In this regard, preclinical evidence especially focusing on the development of smart materials and drug delivery systems will be summarized. Moreover, the sarcoma patient management exploiting nanotechnology products will be summed up. Finally, an overlook on future perspectives will be provided.

Vitronectin-based hydrogels recapitulate neuroblastoma growth conditions

The tumor microenvironment plays an important role in cancer development and the use of 3D in vitro systems that decouple different elements of this microenvironment is critical for the study of cancer progression. In neuroblastoma (NB), vitronectin (VN), an extracellular matrix protein, has been linked to poor prognosis and appears as a promising therapeutic target. Here, we developed hydrogels that incorporate VN into 3D polyethylene glycol (PEG) hydrogel networks to recapitulate the native NB microenvironment. The stiffness of the VN/PEG hydrogels was modulated to be comparable to the in vivo values reported for NB tissue samples. We used SK-N-BE (2) NB cells to demonstrate that PEGylated VN promotes cell adhesion as the native protein does. Furthermore, the PEGylation of VN allows its crosslinking into the hydrogel network, providing VN retention within the hydrogels that support viable cells in 3D. Confocal imaging and ELISA assays indicate that cells secrete VN also in the hydrogels and continue to reorganize their 3D environment. Overall, the 3D VN-based PEG hydrogels recapitulate the complexity of the native tumor extracellular matrix, showing that VN-cell interaction plays a key role in NB aggressiveness, and that VN could potentially be targeted in preclinical drug studies performed on the presented hydrogels.

A murine mesenchymal stem cell model for initiating events in osteosarcomagenesis points to CDK4/CDK6 inhibition as a therapeutic target

Osteosarcoma is a high-grade bone-forming neoplasm, with a complex genome. Tumours frequently show chromothripsis, many deletions, translocations and copy number alterations. Alterations in the p53 or Rb pathway are the most common genetic alterations identified in osteosarcoma. Using spontaneously transformed murine mesenchymal stem cells (MSCs) which formed sarcoma after subcutaneous injection into mice, it was previously demonstrated that p53 is most often involved in the transformation towards sarcomas with complex genomics, including osteosarcoma. In the current study, not only loss of p53 but also loss of p16^Ink4a is shown to be a driver of osteosarcomagenesis: murine MSCs with deficient p15^Ink4b, p16^Ink4a, or p19^Arf transform earlier compared to wild-type murine MSCs. Furthermore, in a panel of nine spontaneously transformed murine MSCs, alterations in p15^Ink4b, p16^Ink4a, or p19^Arf were observed in eight out of nine cases. Alterations in the Rb/p16 pathway could indicate that osteosarcoma cells are vulnerable to CDK4/CDK6 inhibitor treatment. Indeed, using two-dimensional (n = 7) and three-dimensional (n = 3) cultures of human osteosarcoma cell lines, it was shown that osteosarcoma cells with defective p16^INK4A are sensitive to the CDK4/CDK6 inhibitor palbociclib after 72-hour treatment. A tissue microarray analysis of 109 primary tumour biopsies revealed a subset of patients (20-23%) with intact Rb, but defective p16 or overexpression of CDK4 and/or CDK6. These patients might benefit from CDK4/CDK6 inhibition, therefore our results are promising and might be translated to the clinic.

Cancer Stem Cells in Tumor Modeling: Challenges and Future Directions

Microfluidic tumors-on-chips models have revolutionized anticancer therapeutic research by creating an ideal microenvironment for cancer cells. The tumor microenvironment (TME) includes various cell types and cancer stem cells (CSCs), which are postulated to regulate the growth, invasion, and migratory behavior of tumor cells. In this review, the biological niches of the TME and cancer cell behavior focusing on the behavior of CSCs are summarized. Conventional cancer models such as three-dimensional cultures and organoid models are reviewed. Opportunities for the incorporation of CSCs with tumors-on-chips are then discussed for creating tumor invasion models. Such models will represent a paradigm shift in the cancer community by allowing oncologists and clinicians to predict better which cancer patients will benefit from chemotherapy treatments.

The mystery behind the nostrils - technical clues for successful nasal epithelial cell cultivation

OBJECTIVES

Research involving the nose reveals important information regarding the morphology and physiology of the epithelium and its molecular response to agents. The role of nasal epithelial cells and other cell subsets within the nasal epithelium play an interesting translational split between experimental and clinical research studying respiratory disorders or pathogen reactions. With an additional technical manuscript including a detailed description of important technical aspects, tips, tricks, and nuances for a successful culturing of primary, human nasal epithelial cells (NAEPCs), we here aim to improve the process of communication between experimentalists and physicians, supporting the purpose of a fruitful work for future translational projects.

METHODS

Based on previous work on various complex culture models of subject-derived NAEPCs, this additional manuscript harmonizes previously published facts combined with own experiences for a trouble-free implementation in laboratories.

RESULTS

A well-designed experimental question is essential prior to the establishment of different NAEPCs culture models. The correct method of cell extraction from the nasal cavity is essential and represent an important basis for successful culture work. Prior enzymatic processing of biopsy specimens, cell culture materials, collagenization procedure, culture conditions, and choice of culture medium are some important practical notes that increase the quality of the culture. Moreover, protocols on imaging techniques including histologic and electron microscopy must be adapted for NAEPC culture. Adapted flow cytometric protocols and transepithelial electrical resistance measurements can add valuable information.

OUTLOOK

A successful culturing of NAEPCs can provide an important basis for genetic studies and the implementation of omics-science, which is increasingly receiving broad attention in the scientific community. The common aim of in vitro 'mini-noses' will be a breakthrough in laboratories aiming to perform research under in vivo conditions. Here, organoid models are interesting models presenting a basis for translational studies.

Three-dimensional printed implant for reconstruction of pelvic bone after removal of giant chondrosarcoma: a case report

Background

Three-dimensional (3D) reconstruction has been used for various diseases, but few reports have described its application in pelvic reconstruction after removal of giant chondrosarcoma. Case reports describing the clinical application of personalized 3D-printed titanium implants are needed for future clinical reference.

Case presentation: We herein describe a 29-year-old woman with a giant chondrosarcoma treated with a personalized 3D titanium implant. The surgery was successful, and the patient recovered with significant pain relief and good functional recovery after the surgery. No implant-related complications occurred during the 12-month follow-up. The current case represents successful application of 3D printing technology to the treatment of a massive bone defect due to the removal of a giant osteoporotic tumor.

Conclusions

Personalized 3D titanium implants can be used in the reconstruction of massive bone defects after the removal of giant pelvic sarcomas. The methodology and results described in the current case report can be a used as reference in the treatment of similar cases in future.

PDX-Derived Ewing's Sarcoma Cells Retain High Viability and Disease Phenotype in Alginate Encapsulated Spheroid Cultures

Simple Summary

Ewing’s Sarcoma (ES) is the second most frequent bone tumour in children and young adults, with very aggressive behaviour and significant disease recurrence. To better study the disease and find new therapies, experimental models are needed. Recently, patient-derived xenografts (PDX), obtained by implanting patient tumour samples in immunodeficient mice, have been developed. However, when ES cells are extracted from the patient’s tumour or from PDX and placed on plasticware surfaces, they lose their original 3D configuration, cell identity and function. To overcome these issues, we implemented cultures of PDX-derived ES cells, by making them aggregate to form ES cell spheroids and then encapsulating these 3D spheroids into a hydrogel, alginate, to stabilize the culture. We show that this methodology maintained ES cell viability and intrinsic characteristics of the original ES tumour cells for at least one month and that it is suitable for study the effect of anticancer drugs.

Abstract

Ewing’s Sarcoma (ES) is the second most frequent malignant bone tumour in children and young adults and currently only untargeted chemotherapeutic approaches and surgery are available as treatment, although clinical trials are on-going for recently developed ES-targeted therapies. To study ES pathobiology and develop novel drugs, established cell lines and patient-derived xenografts (PDX) are the most employed experimental models. Nevertheless, the establishment of ES cell lines is difficult and the extensive use of PDX raises economic/ethical concerns. There is a growing consensus regarding the use of 3D cell culture to recapitulate physiological and pathophysiological features of human tissues, including drug sensitivity. Herein, we implemented a 3D cell culture methodology based on encapsulation of PDX-derived ES cell spheroids in alginate and maintenance in agitation-based culture systems. Under these conditions, ES cells displayed high proliferative and metabolic activity, while retaining the typical EWSR1-FLI1 chromosomal translocation. Importantly, 3D cultures presented reduced mouse PDX cell contamination compared to 2D cultures. Finally, we show that these 3D cultures can be employed in drug sensitivity assays, with results similar to those reported for the PDX of origin. In conclusion, this novel 3D cell culture method involving ES-PDX-derived cells is a suitable model to study ES pathobiology and can assist in the development of novel drugs against this disease, complementing PDX studies.

ATR and p-ATR are emerging prognostic biomarkers and DNA damage response targets in ovarian cancer

Background:

Although ataxia-telangiectasia and Rad3 related (ATR) has an established role in the DNA damage response of various cancers, its clinical and prognostic significance in ovarian cancer remains largely unknown. The aims of this study were to assess the expression, function, and clinical prognostic relationship of ATR and phospho-ATR ser428 (p-ATR) in ovarian cancer.

Methods:

We confirmed ATR and p-ATR expression by immunohistochemistry (IHC) in a unique ovarian cancer tissue microarray constructed of paired primary, recurrent, and metastatic tumor tissues from 26 individual patients. ATR-specific small interfering RNA (siRNA) and ATR inhibitor VE-822 were applied to determine the effects of ATR inhibition on ovarian cancer cell proliferation, apoptosis, and DNA damage. ATR expression and the associated proteins of the ATR/Chk1 pathway in ovarian cancer cell lines were evaluated by Western blotting. The clonogenicity was also examined using clonogenic assays. A three dimensional (3D) cell culture model was performed to mimic the in vivo ovarian cancer environment to further validate the effects of ATR inhibition on ovarian cancer cells.

Results:

We show recurrent ovarian cancer tissues express higher levels of ATR and p-ATR than their patient-matched primary tumor counterparts. Additionally, higher expression of p-ATR correlates with decreased survival in ovarian cancer patients. Treatment of ovarian cancer cells with ATR specific siRNA or ATR inhibitor VE-822 led to significant apoptosis and inhibition of cellular proliferation, with reduced phosphorylation of Chk1 (p-Chk1), Cdc25c (p-Cdc25c), Cdc2 (p-Cdc2), and increased expression of cleaved PARP and γH2AX. Inhibition of ATR also suppressed clonogenicity and spheroid growth of ovarian cancer cells.

Conclusion:

Our results support the ATR and p-ATR pathway as a prognostic biomarker, and targeting the ATR machinery is an emerging therapeutic approach in the treatment of ovarian cancer.

Creating In Vitro Three-Dimensional Tumor Models: A Guide for the Biofabrication of a Primary Osteosarcoma Model

Osteosarcoma (OS) is a highly aggressive primary bone tumor. The mainstay for its treatment is multiagent chemotherapy and surgical resection, with a 50-70% 5-year survival rate. Despite the huge effort made by clinicians and researchers in the past 30 years, limited progress has been made to improve patient outcomes. As novel therapeutic approaches for OS become available, such as monoclonal antibodies, small molecules, and immunotherapies, the need for OS preclinical model development becomes equally pressing. Three-dimensional (3D) OS models represent an alternative system to study this tumor: In contrast to two-dimensional monolayers, 3D matrices can recapitulate key elements of the tumor microenvironment (TME), such as the cellular interaction with the bone mineralized matrix. The advancement of tissue engineering and biofabrication techniques enables the incorporation of specific TME aspects into 3D models, to investigate the contribution of individual components to tumor progression and enhance understanding of basic OS biology. The use of biomaterials that mimic the extracellular matrix could also facilitate the testing of drugs targeting the TME itself, allowing a larger range of therapeutics to be tested, while averting the ethical implications and high cost associated with in vivo preclinical models. This review aims at serving as a practical guide by delineating the OS TME ("what it is like") and, in turn, propose various biofabrication strategies to create a 3D model ("how to recreate it"), to improve the in vitro representation of the OS tumor and ultimately generate more accurate drug response profiles.

Cancer stem cells as a therapeutic target in 3D tumor models of human chondrosarcoma: An encouraging future for proline rich polypeptide‑1

Chondrosarcoma is a malignant bone neoplasm that is refractory to chemotherapy and radiation. With no current biological treatments, mutilating surgical resection is the only effective treatment. Proline rich polypeptide 1 (PRP-1), which is a 15-amino acid inhibitor of mammalian target of rapamycin complex-1 (mTORC1), has been indicated to exert cytostatic and immunomodulatory properties in human chondrosarcoma cells in a monolayer. The aim of the present study was to evaluate the effects of PRP-1 on an in vitro 3D chondrosarcoma tumor model, known as spheroids, and on the cancer stem cells (CSCs) which form spheroids. JJ012 cells were cultured and treated with PRP-1. An ALDEFLUOR™ assay was conducted (with N,N-diethylaminobenzaldehyde as the negative control) to assess aldehyde dehydrogenase (ALDH) activity (a recognized CSC marker), and bulk JJ012, ALDH^high and PRP-1 treated ALDH^low cells were sorted using flow cytometry. Colony formation and spheroid formation assays of cell fractions, including CSCs, were used to compare the PRP-1-treated groups with the control. CSCs were assessed for early apoptosis and cell death with a modified Annexin V/propidium iodide assay. Western blotting was used to identify mesenchymal stem cell markers (STRO1, CD44 and STAT3), and spheroid self-renewal assays were also conducted. A clonogenic dose-response assay demonstrated that 20 µg/ml PRP-1 was the most effective dose for reducing colony formation capacity. Furthermore, CSC spheroid growth was significantly reduced with increasing doses of PRP-1. Annexin V analysis demonstrated that PRP-1 induced CSC cell death, and that this was not attributed to apoptosis or necrosis. Western blot analysis confirmed the expression of mesenchymal markers, and the spheroid self-renewal assay confirmed the presence of self-renewing CSCs. The results of the present study demonstrate that PRP-1 eliminates anchorage independent CSC growth and spheroid formation, indicating that PRP-1 likely inhibits tumor formation in a murine model. Additionally, a decrease in non-CSC bulk tumor cells indicates an advantageous decline in tumor stromal cells. These findings confirm that PRP-1 inhibits CSC proliferation in a 3D tumor model which mimics the behavior of chondrosarcoma in vivo.

Modeling the Tumor Microenvironment and Pathogenic Signaling in Bone Sarcoma

Investigations of cancer biology and screening of potential therapeutics for efficacy and safety begin in the preclinical laboratory setting. A staple of most basic research in cancer involves the use of tissue culture plates, on which immortalized cell lines are grown in monolayers. However, this practice has been in use for over six decades and does not account for vital elements of the tumor microenvironment that are thought to aid in initiation, propagation, and ultimately, metastasis of cancer. Furthermore, information gleaned from these techniques does not always translate to animal models or, more crucially, clinical trials in cancer patients. Osteosarcoma (OS) and Ewing sarcoma (ES) are the most common primary tumors of bone, but outcomes for patients with metastatic or recurrent disease have stagnated in recent decades. The unique elements of the bone tumor microenvironment have been shown to play critical roles in the pathogenesis of these tumors and thus should be incorporated in the preclinical models of these diseases. In recent years, the field of tissue engineering has leveraged techniques used in designing scaffolds for regenerative medicine to engineer preclinical tumor models that incorporate spatiotemporal control of physical and biological elements. We herein review the clinical aspects of OS and ES, critical elements present in the sarcoma microenvironment, and engineering approaches to model the bone tumor microenvironment. Impact statement The current paradigm of cancer biology investigation and therapeutic testing relies heavily on monolayer, monoculture methods developed over half a century ago. However, these methods often lack essential hallmarks of the cancer microenvironment that contribute to tumor pathogenesis. Tissue engineers incorporate scaffolds, mechanical forces, cells, and bioactive signals into biological environments to drive cell phenotype. Investigators of bone sarcomas, aggressive tumors that often rob patients of decades of life, have begun to use tissue engineering techniques to devise in vitro models for these diseases. Their efforts highlight how critical elements of the cancer microenvironment directly affect tumor signaling and pathogenesis.

Myc is a prognostic biomarker and potential therapeutic target in osteosarcoma

Background

Over the past four decades, outcomes for osteosarcoma patients have plateaued as there have been few emerging therapies showing clinical results. Thus, the identification of novel biomarkers and therapeutic strategies are urgently needed to address these primary obstacles in patient care. Although the Myc-oncogene has known roles in oncogenesis and cancer cell growth, its expression and function in osteosarcoma are largely unknown.

Methods

Expression of Myc was determined by Western blotting of osteosarcoma cell lines and patient tissues, and by immunohistochemistry of a unique osteosarcoma tissue microarray (TMA) constructed from 70 patient samples with extensive follow-up data. Myc specific siRNA and inhibitor 10058-F4 were applied to examine the effect of Myc inhibition on osteosarcoma cell proliferation. The clonogenicity and migration activity was determined by clonogenic and wound-healing assays. A mimic in vivo assay, three-dimensional (3D) cell culture model, was performed to further validate the effect of Myc inhibition on osteosarcoma cell tumorigenic markers.

Results

Myc was significantly overexpressed in human osteosarcoma cell lines compared with normal human osteoblasts, and also highly expressed in fresh osteosarcoma tissues. Higher Myc expression correlated significantly with metastasis and poor prognosis. Through the addition of Myc specific siRNA and inhibitor, we significantly reduced Myc protein expression, resulting in decreased osteosarcoma cell proliferation. Inhibition of Myc also suppressed the migration, clonogenicity, and spheroid growth of osteosarcoma cells.

Conclusion

Our results support Myc as an emerging prognostic biomarker and therapeutic target in osteosarcoma therapy.

A three-dimensional bioprinted model to evaluate the effect of stiffness on neuroblastoma cell cluster dynamics and behavior

Three-dimensional (3D) bioprinted culture systems allow to accurately control microenvironment components and analyze their effects at cellular and tissue levels. The main objective of this study was to identify, quantify and localize the effects of physical-chemical communication signals between tumor cells and the surrounding biomaterial stiffness over time, defining how aggressiveness increases in SK-N-BE(2) neuroblastoma (NB) cell line. Biomimetic hydrogels with SK-N-BE(2) cells, methacrylated gelatin and increasing concentrations of methacrylated alginate (AlgMA 0%, 1% and 2%) were used. Young's modulus was used to define the stiffness of bioprinted hydrogels and NB tumors. Stained sections of paraffin-embedded hydrogels were digitally quantified. Human NB and 1% AlgMA hydrogels presented similar Young´s modulus mean, and orthotopic NB mice tumors were equally similar to 0% and 1% AlgMA hydrogels. Porosity increased over time; cell cluster density decreased over time and with stiffness, and cell cluster occupancy generally increased with time and decreased with stiffness. In addition, cell proliferation, mRNA metabolism and antiapoptotic activity advanced over time and with stiffness. Together, this rheological, optical and digital data show the potential of the 3D in vitro cell model described herein to infer how intercellular space stiffness patterns drive the clinical behavior associated with NB patients.

New Advances in the Study of Bone Tumors: A Lesson From the 3D Environment

Bone primary tumors, such as osteosarcoma, are highly aggressive pediatric tumors that in 30% of the cases develop lung metastasis and are characterized by poor prognosis. Bone is also the third most common metastatic site in patients with advanced cancer and once tumor cells become homed to the skeleton, the disease is usually considered incurable, and treatment is only palliative. Bone sarcoma and bone metastasis share the same tissue microenvironment and niches. 3D cultures represent a new promising approach for the study of interactions between tumor cells and other cellular or acellular components of the tumor microenvironment (i.e., fibroblasts, mesenchymal stem cells, bone ECM). Indeed, 3D models can mimic physiological interactions that are crucial to modulate response to soluble paracrine factors, tumor drug resistance and aggressiveness and, in all, these innovative models might be able of bypassing the use of animal-based preclinical cancer models. To date, both static and dynamic 3D cell culture models have been shown to be particularly suited for screening of anticancer agents and might provide accurate information, translating in vitro cell cultures into precision medicine. In this mini-review, we will summarize the current state-of-the-art in the field of bone tumors, both primary and metastatic, illustrating the different methods and techniques employed to realize 3D cell culture systems and new results achieved in a field that paves the way toward personalized medicine.

Tissue engineered models of healthy and malignant human bone marrow

Tissue engineering is becoming increasingly successful in providing in vitro models of human tissues that can be used for ex vivo recapitulation of functional tissues as well as predictive testing of drug efficacy and safety. From simple tissue models to microphysiological platforms comprising multiple tissue types connected by vascular perfusion, these "tissues on a chip" are emerging as a fast track application for tissue engineering, with great potential for modeling diseases and supporting the development of new drugs and therapeutic targets. We focus here on tissue engineering of the hematopoietic stem and progenitor cell compartment and the malignancies that can develop in the human bone marrow. Our overall goal is to demonstrate the utility and interconnectedness of improvements in bioengineering methods developed in one area of bone marrow studies for the remaining, seemingly disparate, bone marrow fields.

Metastatic tumor cells detection and anti-metastatic potential with vesicular stomatitis virus in immunocompetent murine model of osteosarcoma

Sarcomas are associated with a high incidence of lung metastasis, which leads to a high-risk of cancer death. This study was performed to explore the pre-clinical theranostic potential of a novel fully functional recombinant vesicular stomatitis virus carrying imaging gene Katushka (rVSV-K), as virotherapy and circulating tumor cells (CTCs) detection in the syngeneic mouse model of osteosarcoma with spontaneous pulmonary metastases. Recombinant VSV-K was generated and evaluated in vitro on human and murine osteosarcoma cells. Spontaneous osteosarcoma metastases were established in immune-competent mice by implanting subcutaneously syngeneic osteosarcoma LM8 cells. The vector was injected into the tumor-bearing mice via jugular vein either once or repeatedly. To assess effectiveness, primary tumor growth and development of lung metastasis as well as survival were evaluated. We found that rVSV-K efficiently replicated in and killed all osteosarcoma cell lines in time-dependent manners. Both single or repeated systemic injections of the virus did not inhibit the growth of the primary tumor, but the repeated administration could effectively suppress the development of lung metastases and was likely responsible for the observed increase in survival. Furthermore, we demonstrated, for the first time, that CTCs in blood samples from syngeneic osteosarcoma-bearing mice were successfully detected by utilizing rVSV-K ex vivo. Our results show that repeated systemic injections of rVSV-K are an effective anti-metastatic agent against osteosarcoma in immune-competent mice and this virus to be a useful tool for detection of osteosarcoma CTCs, suggesting that further development of future viral-based theranostic approach in patients with osteosarcoma is warranted. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2562-2569, 2018.

Colorectal tumor 3Din vitromodels: advantages of biofabrication for the recapitulation of early stages of tumour development

The majority of cancer-relatedin vitrostudies are conducted on cell monolayers or spheroids. Although this approach has led to key discoveries, it still has a poor outcome in recapitulating the different stages of tumor development. The advent of novel three-dimensional (3D) systems and technological methods for their fabrication is set to improve the field, offering a more physiologically relevant and high throughputin vitrosystem for the study of tumor development and treatment. Here we describe the fabrication of alginate-based 3D models that recapitulate the early stages of colorectal cancer, tracking two of the main biomarkers for tumor development: CD44 and HIF-1α. We optimized the fabrication process to obtain alginate micro-beads with controlled size and stiffness, mimicking the early stages of colorectal cancer. Human colorectal HCT-116 cancer cells were encapsulated with controlled initial number, and cell viability and protein expression of said 3Din vitromodels was compared to that of current gold standards (cell monolayers and spheroids). Our results evidenced that encapsulated HCT-116 demonstrated a high viability, increase in stem-like cell populations (increased expression of CD44) and reduced hypoxic regions (lower HIF-1a expression) compared to spheroid cultures. In conclusion we show that our biofabricated system is a highly reproducible and easily accessible alternative to study cell behavior, allowing to better mimic the early stages of colorectal cancer in comparison to otherin vitromodels. The use of biofabricatedin vitromodels will improve the translatability of results, in particular when testing strategies for therapeutic intervention.

Relevance of 3d culture systems to study osteosarcoma environment

Osteosarcoma (OS) is the most common primary malignant tumor of bone, which preferentially develops lung metastasis. Although standard chemotherapy has significantly improved long-term survival over the past few decades, the outcome for patients with metastatic or recurrent OS remains dramatically poor. Novel therapies are therefore required to slow progression and eradicate the disease. Furthermore, to better understand the cellular and molecular mechanisms responsible for OS onset and progression, the development of novel predictive culture systems resembling the native three-dimensional (3D) tumor microenvironment are mandatory. ‘Tumor engineering’ approaches radically changed the previous scenario, through the development of advanced and alternative 3D cell culture in vitro models able to tightly mimic the in vivo tumor microenvironment.

In this review, we will summarize the state of the art in this novel area, illustrating the different methods and techniques employed to realize 3D OS cell culture models and we report the achieved results, which highlight the efficacy of these models in reproducing the tumor milieu. Although data need to be further validated, the scientific studies reviewed here are certainly promising and give new insights into the clinical practice.