Heralding a new paradigm in 3D tumor modeling

Contribution of the ELRs to the development of advanced in vitro models

Developing in vitro models that accurately mimic the microenvironment of biological structures or processes holds substantial promise for gaining insights into specific biological functions. In the field of tissue engineering and regenerative medicine, in vitro models able to capture the precise structural, topographical, and functional complexity of living tissues, prove to be valuable tools for comprehending disease mechanisms, assessing drug responses, and serving as alternatives or complements to animal testing. The choice of the right biomaterial and fabrication technique for the development of these in vitro models plays an important role in their functionality. In this sense, elastin-like recombinamers (ELRs) have emerged as an important tool for the fabrication of in vitro models overcoming the challenges encountered in natural and synthetic materials due to their intrinsic properties, such as phase transition behavior, tunable biological properties, viscoelasticity, and easy processability. In this review article, we will delve into the use of ELRs for molecular models of intrinsically disordered proteins (IDPs), as well as for the development of in vitro 3D models for regenerative medicine. The easy processability of the ELRs and their rational design has allowed their use for the development of spheroids and organoids, or bioinks for 3D bioprinting. Thus, incorporating ELRs into the toolkit of biomaterials used for the fabrication of in vitro models, represents a transformative step forward in improving the accuracy, efficiency, and functionality of these models, and opening up a wide range of possibilities in combination with advanced biofabrication techniques that remains to be explored.

Aged breast matrix bound vesicles promote breast cancer invasiveness

Aging is one of the inherent risk factors for breast cancer. Although the influence of age-related cellular alterations on breast cancer development has been extensively explored, little is known about the alterations in the aging breast tissue microenvironment, specifically the extracellular matrix (ECM). Here, for the first time in literature, we have identified tissue resident matrix bound vesicles (MBVs) within the healthy mouse breast ECM, investigated and compared their characteristics in young and aged healthy breast tissues, and studied the effects of these MBVs on normal (KTB21) and cancerous (MDA-MB-231) human mammary epithelial cells with respect to the tissue age that they are extracted from. Using vesicle labeling technology, we were able to visualize cellular uptake of the MBVs directly from the native decellularized tissue sections, showing that these MBVs have regulatory roles in the tissue microenvironment. We mimicked the ECM by embedding the MBVs in collagen gels, and showed that MBVs could be taken up by the cells. The miRNA and cytokine profiling showed that MBVs shifted towards a more tumorigenic and invasive phenotype with age, as evidenced by the more pronounced presence of cancer-associated cytokines, and higher expression levels of oncomiRs miR-10b, miR-30e, and miR-210 in MBVs isolated from aged mice. When treated with MBVs or these upregulated factors, KTB21 and MDA-MB-231 cells showed significantly higher motility and invasion compared to untreated controls. Treatment of cells with a cocktail of miRNAs (miR-10b, miR-30e, and miR-210) or with the agonist of adiponectin (AdipoRon), which both were enriched in the aged MBVs, recapitulated the effect of aged MBVs on cells. This study shows for the first time that the MBVs have a regulatory role in the tissue microenvironment and that the MBV contents change towards cancer-promoting upon aging. Studying the effects of MBVs and their cargos on cellular behavior could lead to a better understanding of the critical roles of MBVs played in breast cancer progression and metastasis.

Engineered 3D ex vivo models to recapitulate the complex stromal and immune interactions within the tumor microenvironment

Cancer thrives in a complex environment where interactions between cellular and acellular components, surrounding the tumor, play a crucial role in disease development and progression. Despite significant progress in cancer research, the mechanism driving tumor growth and therapeutic outcomes remains elusive. Two-dimensional (2D) cell culture assays and in vivo animal models are commonly used in cancer research and therapeutic testing. However, these models suffer from numerous shortcomings including lack of key features of the tumor microenvironment (TME) & cellular composition, cost, and ethical clearance. To that end, there is an increased interest in incorporating and elucidating the influence of TME on cancer progression. Advancements in 3D-engineered ex vivo models, leveraging biomaterials and microengineering technologies, have provided an unprecedented ability to reconstruct native-like bioengineered cancer models to study the heterotypic interactions of TME with a spatiotemporal organization. These bioengineered cancer models have shown excellent capabilities to bridge the gap between oversimplified 2D systems and animal models. In this review article, we primarily provide an overview of the immune and stromal cellular components of the TME and then discuss the latest state-of-the-art 3D-engineered ex vivo platforms aiming to recapitulate the complex TME features. The engineered TME model, discussed herein, are categorized into three main sections according to the cellular interactions within TME: (i) Tumor-Stromal interactions, (ii) Tumor-Immune interactions, and (iii) Complex TME interactions. Finally, we will conclude the article with a perspective on how these models can be instrumental for cancer translational studies and therapeutic testing.

Advances in screening hyperthermic nanomedicines in 3D tumor models

Hyperthermic nanomedicines are particularly relevant for tackling human cancer, providing a valuable alternative to conventional therapeutics. The early-stage preclinical performance evaluation of such anti-cancer treatments is conventionally performed in flat 2D cell cultures that do not mimic the volumetric heat transfer occurring in human tumors. Recently, improvements in bioengineered 3D in vitro models have unlocked the opportunity to recapitulate major tumor microenvironment hallmarks and generate highly informative readouts that can contribute to accelerating the discovery and validation of efficient hyperthermic treatments. Leveraging on this, herein we aim to showcase the potential of engineered physiomimetic 3D tumor models for evaluating the preclinical efficacy of hyperthermic nanomedicines, featuring the main advantages and design considerations under diverse testing scenarios. The most recent applications of 3D tumor models for screening photo- and/or magnetic nanomedicines will be discussed, either as standalone systems or in combinatorial approaches with other anti-cancer therapeutics. We envision that breakthroughs toward developing multi-functional 3D platforms for hyperthermia onset and follow-up will contribute to a more expedited discovery of top-performing hyperthermic therapies in a preclinical setting before their in vivo screening.

Organoid co-culture models of the tumor microenvironment promote precision medicine

In recent years, the three-dimensional (3D) culture system has emerged as a promising preclinical model for tumor research owing to its ability to replicate the tissue structure and molecular characteristics of solid tumors in vivo. This system offers several advantages, including high throughput, efficiency, and retention of tumor heterogeneity. Traditional Matrigel-submerged organoid cultures primarily support the long-term proliferation of epithelial cells. One solution for the exploration of the tumor microenvironment is a reconstitution approach involving the introduction of exogenous cell types, either in dual, triple or even multiple combinations. Another solution is a holistic approach including patient-derived tumor fragments, air-liquid interface, suspension 3D culture, and microfluidic tumor-on-chip models. Organoid co-culture models have also gained popularity for studying the tumor microenvironment, evaluating tumor immunotherapy, identifying predictive biomarkers, screening for effective drugs, and modeling infections. By leveraging these 3D culture systems, it is hoped to advance the clinical application of therapeutic approaches and improve patient outcomes.

Engineering Heterogeneous Tumor Models for Biomedical Applications

Tumor tissue engineering holds great promise for replicating the physiological and behavioral characteristics of tumors in vitro. Advances in this field have led to new opportunities for studying the tumor microenvironment and exploring potential anti-cancer therapeutics. However, the main obstacle to the widespread adoption of tumor models is the poor understanding and insufficient reconstruction of tumor heterogeneity. In this review, the current progress of engineering heterogeneous tumor models is discussed. First, the major components of tumor heterogeneity are summarized, which encompasses various signaling pathways, cell proliferations, and spatial configurations. Then, contemporary approaches are elucidated in tumor engineering that are guided by fundamental principles of tumor biology, and the potential of a bottom-up approach in tumor engineering is highlighted. Additionally, the characterization approaches and biomedical applications of tumor models are discussed, emphasizing the significant role of engineered tumor models in scientific research and clinical trials. Lastly, the challenges of heterogeneous tumor models in promoting oncology research and tumor therapy are described and key directions for future research are provided.

Microphysiological systems as reliable drug discovery and evaluation tools: Evolution from innovation to maturity

Microphysiological systems (MPSs), also known as organ-on-chip or disease-on-chip, have recently emerged to reconstitute the in vivo cellular microenvironment of various organs and diseases on in vitro platforms. These microfluidics-based platforms are developed to provide reliable drug discovery and regulatory evaluation testbeds. Despite recent emergences and advances of various MPS platforms, their adoption of drug discovery and evaluation processes still lags. This delay is mainly due to a lack of rigorous standards with reproducibility and reliability, and practical difficulties to be adopted in pharmaceutical research and industry settings. This review discusses the current and potential use of MPS platforms in drug discovery processes while considering the context of several key steps during drug discovery processes, including target identification and validation, preclinical evaluation, and clinical trials. Opportunities and challenges are also discussed for the broader dissemination and adoption of MPSs in various drug discovery and regulatory evaluation steps. Addressing these challenges will transform long and expensive drug discovery and evaluation processes into more efficient discovery, screening, and approval of innovative drugs.

Breast tumor-on-chip: from the tumor microenvironment to medical applications

With the development of microfluidic technology, tumor-on-chip models have gradually become a new tool for the study of breast cancer because they can simulate more key factors of the tumor microenvironment compared with traditional models in vitro. Here, we review up-to-date advancements in breast tumor-on-chip models. We summarize and analyze the breast tumor microenvironment (TME), preclinical breast cancer models for TME simulation, fabrication methods of tumor-on-chip models, tumor-on-chip models for TME reconstruction, and applications of breast tumor-on-chip models and provide a perspective on breast tumor-on-chip models. This review will contribute to the construction and design of microenvironments for breast tumor-on-chip models, even the development of the pharmaceutical field, personalized/precision therapy, and clinical medicine.

Elastin-like Recombinamer Hydrogels as Platforms for Breast Cancer Modeling

The involvement of the extracellular matrix (ECM) in tumor progression has motivated the development of biomaterials mimicking the tumor ECM to develop more predictive cancer models. Particularly, polypeptides based on elastin could be an interesting approach to mimic the ECM due to their tunable properties. Here, we demonstrated that elastin-like recombinamer (ELR) hydrogels can be suitable biomaterials to develop breast cancer models. This hydrogel was formed by two ELR polypeptides, one containing sequences biodegradable by matrix metalloproteinase and cyclooctyne and the other carrying arginylglycylaspartic acid and azide groups to allow cell adhesion, biodegradability, and suitable stiffness through "click-chemistry" cross-linking. Our findings show that breast cancer or nontumorigenic breast cells showed high viability and cell proliferation for up to 7 days. MCF7 and MCF10A formed spheroids whereas MDA-MB-231 formed cell networks, with the expression of ECM and high drug resistance in all cases, evidencing that ELR hydrogels are a promising biomaterial for breast cancer modeling.

A Simple and Fast Method for the Formation and Downstream Processing of Cancer-Cell-Derived 3D Spheroids: An Example Using Nicotine-Treated A549 Lung Cancer 3D Spheres

Although 2D in vitro cancer cell cultures have been used for decades as a first line-of-research tool to investigate antitumoral drugs and treatments, their use presents many drawbacks, including the poor resemblance of such cultures to the characteristics of in vivo tumors. To mitigate these drawbacks, 3D culture models have emerged as a more representative alternative. Cancer cells cultured as 3D structures have the advantage of resembling solid tumors in their architecture and in their resistance to chemotherapeutic drugs, in part because of restrained drug penetration. Additionally, these 3D structures create a more physiological environment for the study of immune cell invasion and migration, comparable to solid tumors. In this paper, we describe a fast and cost-effective step-by-step protocol for the generation of 3D spheres using ultra-low-attachment (ULA) multiwell plates, which can be incorporated into the normal workflow of any laboratory. Using this protocol, spheroids of different human cancer cell lines can be obtained and can then be characterized on the basis of their morphology, viability, and expression of specific markers.

Three Dimensional Models of Endocrine Organs and Target Tissues Regulated by the Endocrine System

Immortalized cell lines originating from tumors and cultured in monolayers in vitro display consistent behavior and response, and generate reproducible results across laboratories. However, for certain endpoints, these cell lines behave quite differently from the original solid tumors. Thereby, the homogeneity of immortalized cell lines and two-dimensionality of monolayer cultures deters from the development of new therapies and translatability of results to the more complex situation in vivo. Organoids originating from tissue biopsies and spheroids from cell lines mimic the heterogeneous and multidimensional characteristics of tumor cells in 3D structures in vitro. Thus, they have the advantage of recapitulating the more complex tissue architecture of solid tumors. In this review, we discuss recent efforts in basic and preclinical cancer research to establish methods to generate organoids/spheroids and living biobanks from endocrine tissues and target organs under endocrine control while striving to achieve solutions in personalized medicine.

Prostate cancer and bone: clinical presentation and molecular mechanisms

Prostate cancer (PCa) is an increasingly prevalent health problem in the developed world. Effective treatment options exist for localized PCa, but metastatic PCa has fewer treatment options and shorter patient survival. PCa and bone health are strongly entwined, as PCa commonly metastasizes to the skeleton. Since androgen receptor signaling drives PCa growth, androgen-deprivation therapy whose sequelae reduce bone strength constitutes the foundation of advanced PCa treatment. The homeostatic process of bone remodeling - produced by concerted actions of bone-building osteoblasts, bone-resorbing osteoclasts, and regulatory osteocytes - may also be subverted by PCa to promote metastatic growth. Mechanisms driving skeletal development and homeostasis, such as regional hypoxia or matrix-embedded growth factors, may be subjugated by bone metastatic PCa. In this way, the biology that sustains bone is integrated into adaptive mechanisms for the growth and survival of PCa in bone. Skeletally metastatic PCa is difficult to investigate due to the entwined nature of bone biology and cancer biology. Herein, we survey PCa from origin, presentation, and clinical treatment to bone composition and structure and molecular mediators of PCa metastasis to bone. Our intent is to quickly yet effectively reduce barriers to team science across multiple disciplines that focuses on PCa and metastatic bone disease. We also introduce concepts of tissue engineering as a novel perspective to model, capture, and study complex cancer-microenvironment interactions.

A 3D Perfusable Platform for In Vitro Culture of Patient Derived Xenografts

Many advanced cancer models, such as patient-derived xenografts (PDXs), offer significant benefits in their preservation of the native tumor's heterogeneity and susceptibility to treatments, but face significant barriers to use in their reliance on a rodent host for propagation and screening. PDXs remain difficult to implement in vitro, particularly in configurations that enable both detailed cellular analysis and high-throughput screening (HTS). Complex multilineage co-cultures with stromal fibroblasts, endothelium, and other cellular and structural components of the tumor microenvironment (TME) further complicate ex vivo implementation. Herein, the culture of multiple prostate cancer (PCa)-derived PDX models as 3D clusters within engineered biomimetic hydrogel matrices, in a HTS-compatible multiwell microfluidic format, alongside bone marrow-derived stromal cells and a perfused endothelial channel. Polymeric hydrogel matrices are customized for each cell type, enabling cell survival in vitro and facile imaging across all conditions. PCa PDXs demonstrate unique morphologies and reliance on TME partners, retention of known phenotype, and expected sensitivity or resistance to standard PCa therapeutics. This novel integration of technologies provides a fully human model, and expands the information to be gathered from each specimen, while avoiding the time and labor involved with animal-based testing.

Aged Breast Matrix Bound Vesicles Promote Breast Cancer Invasiveness

Aging is one of the inherent risk factors for breast cancer. Although the influence of age-related cellular alterations on breast cancer development has been extensively explored, little is known about the alterations in the aging breast tissue microenvironment, specifically the extracellular matrix (ECM). Here, for the first time in literature, we have identified tissue resident matrix bound vesicles (MBVs) within the healthy mouse breast ECM, investigated and compared their characteristics in young and aged healthy breast tissues, and studied the effects of these MBVs on normal (KTB21) and cancerous (MDA-MB-231) human mammary epithelial cells with respect to the tissue age that they are extracted from. Using vesicle labeling technology, we were able to visualize cellular uptake of the MBVs directly from the native decellularized tissue sections, showing that these MBVs have regulatory roles in the tissue microenvironment. We mimicked the ECM by embedding the MBVs in collagen gels, and showed that MBVs could be taken up by the cells. The miRNA and cytokine profiling showed that MBVs shifted towards a more tumorigenic and invasive phenotype with age, as evidenced by the more pronounced presence of cancer-associated cytokines, and higher expression levels of oncomiRs miR-10b, miR-30e, and miR-210 in MBVs isolated from aged mice. When treated with MBVs or these upregulated factors, KTB21 and MDA-MB-231 cells showed significantly higher motility and invasion compared to untreated controls. Treatment of cells with a cocktail of miRNAs (miR-10b, miR-30e, and miR-210) or with the agonist of adiponectin (AdipoRon), which both were enriched in the aged MBVs, recapitulated the effect of aged MBVs on cells. This study shows for the first time that the MBVs have a regulatory role in the tissue microenvironment and that the MBV contents change towards cancer-promoting upon aging. Studying the effects of MBVs and their cargos on cellular behavior could lead to a better understanding of the critical roles of MBVs played in breast cancer progression and metastasis.

Lipid Membrane Alterations in Tumor Spheroids Revealed by Fluorescence Lifetime Microscopy Imaging

Three-dimensional (3D) cultured tumor spheroid models, as one type of in vitro model, have been proven to have more physiological similarities to in vivo animal models than cells in 2D cultures. Tumor spheroids have been widely used in preclinical experiments of anticancer drug treatments, providing reliable data in pathogenetic research. Currently, different 3D cell culture conditions, even in the same cell line, generate heterogeneous spheroids in morphology and size, resulting in different growth rates or drug-killing responses. Therefore, the measurement and evaluation of the properties of tumor spheroids have become highly demanding tasks with huge challenges. For functional characterization of tumor spheroids, the microenvironment sensitivity and quantitative properties of the fluorescence lifetime microscopy imaging (FLIM) technique have great advantages for improving the reliability of cell physiological testing. In this paper, we have proposed a FLIM-based approach to observe the lipid components labeled with Nile red of cells in both 3D and 2D cultures. The imaging data and analysis provided basic information on the sizes, morphologies, and cell membrane fluorescence lifetime values of the tumor spheroids. FLIM data showed that the microenvironment of the cell membrane in the 3D model was largely altered compared to that in the 2D culture. Next, a series of parameters that may influence the lipid components of tumor cells and tumor spheroids were tested by FLIM, including pH, viscosity, and polarity. The results showed that pH and viscosity contributed little to the change in fluorescence lifetime values, while the change in cell membrane polarity was the main cause of the alterations in fluorescence lifetime data, suggesting that cell membrane polarity should be considered a marker in distinguishing tumor spheroids from cellular physiological status. In conclusion, this FLIM-based testing process has been proven to be a quantitative method for measuring the differences between the cells of the 3D model from the 2D cultured cells with satisfactory sensitivity and accuracy, providing a high potential standard assay in the quality evaluation and control of tumor spheroids for future anticancer drug development.

ISG15 is a potential therapeutic target for osteosarcoma: a comprehensive analysis based on bioinformatics and in vitro experiments

BACKGROUND

The expression of aberrant interferon-stimulated gene 15 (ISG15) is connected with various human diseases, including cancer. ISG15 is involved in tumor formation and metastasis. However, its role in osteosarcoma is uncertain.

METHODS

ISG15 expression in pan-cancer from RNA Sequencing data were obtained from The Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) databases. The relationship between ISG15 expression and prognosis was assessed through TCGA clinical survival data. Immunohistochemistry (IHC) images of ISG15 were retrieved using the Human Protein Atlas to analyze the differences in selected normal and tumor tissues. Gene enrichment analysis and signaling pathway analysis were used to assess the potential role of ISG15 in sarcoma, and the correlation between ISG15 expressions and immune cell infiltration levels was estimated by immune infiltration analysis. The expression levels of ISG15 were assessed by qRT-PCR and IHC. Colony formation, wound healing assay and transwell assay were used to detect the effects of ISG15 on the biological behaviors of osteosarcoma cells. The correlation between ISG15 levels and CD8+/CD68+ cells was further examined by double-labeled immunofluorescence. The chemotactic effect of ISG15 on CD8+/CD68+ cells was demonstrated by chemotactic experiments and flow cytometry.

RESULTS

ISG15 was highly expressed in most cancers, while high ISG15 expression was significantly correlated with poor overall survival. Gene enrichment analysis in sarcoma suggested that antigen processing and presentation might be involved in the oncogenic mechanism of ISG15. Further immune infiltration analysis showed that high ISG15 expression might reflect the infiltration level of certain immune cells. Additionally, our verification showed that ISG15 was significantly related to the occurrence and metastasis of osteosarcoma, and knockdown of ISG15 significantly altered cell biological behavior, resulting in decreased proliferation, migration and invasion capabilities of osteosarcoma cells. The high expression of ISG15 in osteosarcoma tissue was associated with a high level of CD68+ immune cell infiltration while a low level of CD8+ T cell infiltration. CD68+ immune cells were recruited in vitro by overexpression of ISG15, which on the contrary could weaken the chemotaxis of CD8+ T cells.

CONCLUSION

High ISG15 expression is an inherent feature of osteosarcoma and triggers tumorigenesis and metastasis by regulating tumor immunogenicity. ISG15 is expected to be the target of osteosarcoma treatment.

Key aspects for conception and construction of co-culture models of tumor-stroma interactions

The tumor microenvironment is crucial in the initiation and progression of cancers. The interplay between cancer cells and the surrounding stroma shapes the tumor biology and dictates the response to cancer therapies. Consequently, a better understanding of the interactions between cancer cells and different components of the tumor microenvironment will drive progress in developing novel, effective, treatment strategies. Co-cultures can be used to study various aspects of these interactions in detail. This includes studies of paracrine relationships between cancer cells and stromal cells such as fibroblasts, endothelial cells, and immune cells, as well as the influence of physical and mechanical interactions with the extracellular matrix of the tumor microenvironment. The development of novel co-culture models to study the tumor microenvironment has progressed rapidly over recent years. Many of these models have already been shown to be powerful tools for further understanding of the pathophysiological role of the stroma and provide mechanistic insights into tumor-stromal interactions. Here we give a structured overview of different co-culture models that have been established to study tumor-stromal interactions and what we have learnt from these models. We also introduce a set of guidelines for generating and reporting co-culture experiments to facilitate experimental robustness and reproducibility.

Aptamers as Smart Ligands for Targeted Drug Delivery in Cancer Therapy

Undesirable side effects and multidrug tolerance are the main holdbacks to the treatment of cancer in conventional chemotherapy. Fortunately, targeted drug delivery can improve the enrichment of drugs at the target site and reduce toxicity to normal tissues and cells. A targeted drug delivery system is usually composed of a nanocarrier and a targeting component. The targeting component is called a "ligand". Aptamers have high target affinity and specificity, which are identified as attractive and promising ligands. Therefore, aptamers have potential application in the development of smart targeting systems. For instance, aptamers are able to efficiently recognize tumor markers such as nucleolin, mucin, and epidermal growth factor receptor (EGFR). Besides, aptamers can also identify glycoproteins on the surface of tumor cells. Thus, the aptamer-mediated targeted drug delivery system has received extensive attention in the application of cancer therapy. This article reviews the application of aptamers as smart ligands for targeted drug delivery in cancer therapy. Special interest is focused on aptamers as smart ligands, aptamer-conjugated nanocarriers, aptamer targeting strategy for tumor microenvironment (TME), and aptamers that are specified to crucial cancer biomarkers for targeted drug delivery.

A 3D bioprinted tumor model fabricated with gelatin/sodium alginate/decellularized extracellular matrix bioink

109Tissue-engineered scaffolds are more commonly used to construct three-dimensional (3D) tumor models for in vitro studies when compared to the conventional two-dimensional (2D) cell culture because the microenvironments provided by the 3D tumor models closely resemble the in vivo system and could achieve higher success rate when the scaffolds are translated for use in pre-clinical animal model. Physical properties, heterogeneity, and cell behaviors of the model could be regulated to simulate different tumors by changing the components and concentrations of materials. In this study, a novel 3D breast tumor model was fabricated by bioprinting using a bioink that consists of porcine liver-derived decellularized extracellular matrix (dECM) with different concentrations of gelatin and sodium alginate. Primary cells were removed while extracellular matrix components of porcine liver were preserved. The rheological properties of biomimetic bioinks and the physical properties of hybrid scaffolds were investigated, and we found that the addition of gelatin increased hydrophilia and viscoelasticity, while the addition of alginate increased mechanical properties and porosity. The swelling ratio, compression modulus, and porosity could reach 835.43 ± 130.61%, 9.64 ± 0.41 kPa, and 76.62 ± 4.43%, respectively. L929 cells and the mouse breast tumor cells 4T1 were subsequently inoculated to evaluate biocompatibility of the scaffolds and to form the 3D models. The results showed that all scaffolds exhibited good biocompatibility, and the average diameter of tumor spheres could reach 148.52 ± 8.02 μm on 7 d. These findings suggest that the 3D breast tumor model could serve as an effective platform for anticancer drug screening and cancer research in vitro.

A rapid screening platform to coculture bacteria within tumor spheroids

The prevalence of tumor-colonizing bacteria along with advances in synthetic biology are leading to a new generation of living microbial cancer therapies. Because many bacterial systems can be engineered to recombinantly produce therapeutics within tumors, simple and high-throughput experimental platforms are needed to screen the large collections of bacteria candidates and characterize their interactions with cancer cells. Here, we describe a protocol to selectively grow bacteria within the core of tumor spheroids, allowing for their continuous and parallel profiling in physiologically relevant conditions. Specifically, tumor spheroids are incubated with bacteria in a 96-well low-adhesion plate followed by a series of washing steps and an antibiotic selection protocol to confine bacterial growth within the hypoxic and necrotic core of tumor spheroids. This bacteria spheroid coculture (BSCC) system is stable for over 2 weeks, does not require specialized equipment and is compatible with time-lapse microscopy, commercial staining assays and histology that uniquely enable analysis of growth kinetics, viability and spatial distribution of both cellular populations, respectively. We show that the procedure is applicable to multiple tumor cell types and bacterial species by varying protocol parameters and is validated by using animal models. The BSCC platform will allow the study of bacteria-tumor interactions in a continuous manner and facilitate the rapid development of engineered microbial therapies.

Programmable Living Units for Emulating Pancreatic Tumor-Stroma Interplay

Bioengineering close-to-native in vitro models that emulate tumors bioarchitecture and microenvironment is highly appreciable for improving disease modeling toolboxes. Herein, pancreatic cancer living units-so termed cancer-on-a-bead models-are generated. Such user-programmable in vitro platforms exhibit biomimetic multicompartmentalization and tunable integration of cancer associated stromal elements. These stratified units can be rapidly assembled in-air, exhibit reproducible morphological features, tunable size, and recapitulate spatially resolved tumor-stroma extracellular matrix (ECM) niches. Compartmentalization of pancreatic cancer and stromal cells in well-defined ECM microenvironments stimulates the secretion of key biomolecular effectors including transforming growth factor β and Interleukin 1-β, closely emulating the signatures of human pancreatic tumors. Cancer-on-a-bead models also display increased drug resistance to chemotherapeutics when compared to their reductionistic counterparts, reinforcing the importance to differentially model ECM components inclusion and their spatial stratification as observed in vivo. Beyond providing a universal technology that enables spatial modularity in tumor-stroma elements bioengineering, a scalable, in-air fabrication of ECM-tunable 3D platforms that can be leveraged for recapitulating differential matrix composition occurring in other human neoplasias is provided here.

3D-bioprinted cancer-on-a-chip: level-up organotypic in vitro models

Combinatorial conjugation of organ-on-a-chip platforms with additive manufacturing technologies is rapidly emerging as a disruptive approach for upgrading cancer-on-a-chip systems towards anatomic-sized dynamic in vitro models. This valuable technological synergy has potential for giving rise to truly physiomimetic 3D models that better emulate tumor microenvironment elements, bioarchitecture, and response to multidimensional flow dynamics. Herein, we showcase the most recent advances in bioengineering 3D-bioprinted cancer-on-a-chip platforms and provide a comprehensive discussion on design guidelines and possibilities for high-throughput analysis. Such hybrid platforms represent a new generation of highly sophisticated 3D tumor models with improved biomimicry and predictability of therapeutics performance.

Clinical translation of patient-derived tumour organoids- bottlenecks and strategies

Multiple three-dimensional (3D) tumour organoid models assisted by multi-omics and Artificial Intelligence (AI) have contributed greatly to preclinical drug development and precision medicine. The intrinsic ability to maintain genetic and phenotypic heterogeneity of tumours allows for the reconciliation of shortcomings in traditional cancer models. While their utility in preclinical studies have been well established, little progress has been made in translational research and clinical trials. In this review, we identify the major bottlenecks preventing patient-derived tumour organoids (PDTOs) from being used in clinical setting. Unsuitable methods of tissue acquisition, disparities in establishment rates and a lengthy timeline are the limiting factors for use of PDTOs in clinical application. Potential strategies to overcome this include liquid biopsies via circulating tumour cells (CTCs), an automated organoid platform and optical metabolic imaging (OMI). These proposed solutions accelerate and optimize the workflow of a clinical organoid drug screening. As such, PDTOs have the potential for potential applications in clinical oncology to improve patient outcomes. If remarkable progress is made, cancer patients can finally benefit from this revolutionary technology.

Decellularized Pig Kidney with a Micro-Nano Secondary Structure Contributes to Tumor Progression in 3D Tumor Model

In spite of many anti-cancer drugs utilized in clinical treatment, cancer is still one of the diseases with the highest morbidity and mortality worldwide, owing to the complexity and heterogeneity of the tumor microenvironment. Compared with conventional 2D tumor models, 3D scaffolds could provide structures and a microenvironment which stimulate native tumor tissues more accurately. The extracellular matrix (ECM) is the main component of the cell in the microenvironment that is mainly composed of three-dimensional nanofibers, which can form nanoscale fiber networks, while the decellularized extracellular matrix (dECM) has been widely applied to engineered scaffolds. In this study, pig kidney was used as the source material to prepare dECM scaffolds. A chemical crosslinking method was used to improve the mechanical properties and other physical characteristics of the decellularized pig kidney-derived scaffold. Furthermore, a human breast cancer cell line (MCF-7) was used to further investigate the biocompatibility of the scaffold to fabricate a tumor model. The results showed that the existence of nanostructures in the scaffold plays an important role in cell adhesion, proliferation, and differentiation. Therefore, the pig kidney-derived matrix scaffold prepared by decellularization could provide more cell attachment sites, which is conducive to cell adhesion and proliferation, physiological activities, and tumor model construction.

Honeycomb-Like Hydrogel Microspheres for 3D Bulk Construction of Tumor Models

A two-dimensional (2D) cell culture-based model is widely applied to study tumorigenic mechanisms and drug screening. However, it cannot authentically simulate the three-dimensional (3D) microenvironment of solid tumors and provide reliable and predictable data in response to in vivo, thus leading to the research illusions and failure of drug screening. In this study, honeycomb-like gelatin methacryloyl (GelMA) hydrogel microspheres are developed by synchronous photocrosslinking microfluidic technique to construct a 3D model of osteosarcoma. The in vitro study shows that osteosarcoma cells (K7M2) cultured in 3D GelMA microspheres have stronger tumorous stemness, proliferation and migration abilities, more osteoclastogenetic ability, and resistance to chemotherapeutic drugs (DOX) than that of cells in 2D cultures. More importantly, the 3D-cultured K7M2 cells show more tumorigenicity in immunologically sound mice, characterized by shorter tumorigenesis time, larger tumor volume, severe bone destruction, and higher mortality. In conclusion, honeycomb-like porous microsphere scaffolds are constructed with uniform structure by microfluidic technology to massively produce tumor cells with original phenotypes. Those microspheres could recapitulate the physiology microenvironment of tumors, maintain cell-cell and cell-extracellular matrix interactions, and thus provide an effective and convenient strategy for tumor pathogenesis and drug screening research.

Integrated genome and tissue engineering enables screening of cancer vulnerabilities in physiologically relevant perfusable ex vivo cultures

Genetic screens are powerful tools for both resolving biological function and identifying potential therapeutic targets, but require physiologically accurate systems to glean biologically useful information. Here, we enable genetic screens in physiologically relevant ex vivo cancer tissue models by integrating CRISPR-Cas-based genome engineering and biofabrication technologies. We first present a novel method for generating perfusable tissue constructs, and validate its functionality by using it to generate three-dimensional perfusable dense cultures of cancer cell lines and sustain otherwise ex vivo unculturable patient-derived xenografts. Using this system we enable large-scale CRISPR screens in perfused tissue cultures, as well as emulate a novel point-of-care diagnostics scenario of a clinically actionable CRISPR knockout (CRISPRko) screen of genes with FDA-approved drug treatments in ex vivo PDX cell cultures. Our results reveal differences across in vitro and in vivo cancer model systems, and highlight the utility of programmable tissue engineered models for screening therapeutically relevant cancer vulnerabilities.

Emerging Technologies in Multi-Material Bioprinting

Bioprinting, within the emerging field of biofabrication, aims at the fabrication of functional biomimetic constructs. Different 3D bioprinting techniques have been adapted to bioprint cell-laden bioinks. However, single-material bioprinting techniques oftentimes fail to reproduce the complex compositions and diversity of native tissues. Multi-material bioprinting as an emerging approach enables the fabrication of heterogeneous multi-cellular constructs that replicate their host microenvironments better than single-material approaches. Here, bioprinting modalities are reviewed, their being adapted to multi-material bioprinting is discussed, and their advantages and challenges, encompassing both custom-designed and commercially available technologies are analyzed. A perspective of how multi-material bioprinting opens up new opportunities for tissue engineering, tissue model engineering, therapeutics development, and personalized medicine is offered.

Recapitulating the Angiogenic Switch in a Hydrogel-Based 3D In Vitro Tumor-Stroma Model

To ensure nutrient and oxygen supply, tumors beyond a size of 1–2 mm³ need a connection to the vascular system. Thus, tumor cells modify physiological tissue homeostasis by secreting inflammatory and angiogenic cytokines. This leads to the activation of the tumor microenvironment and the turning of the angiogenic switch, resulting in tumor vascularization and growth. To inhibit tumor growth by developing efficient anti-angiogenic therapies, an in depth understanding of the molecular mechanism initiating angiogenesis is essential. Yet so far, predominantly 2D cell cultures or animal models have been used to clarify the interactions within the tumor stroma, resulting in poor transferability of the data obtained to the in vivo situation. Consequently, there is an abundant need for complex, humanized, 3D models in vitro. We established a dextran-hydrogel-based 3D organotypic in vitro model containing microtumor spheroids, macrophages, neutrophils, fibroblasts and endothelial cells, allowing for the analysis of tumor–stroma interactions in a controlled and modifiable environment. During the cultivation period of 21 days, the microtumor spheroids in the model grew in size and endothelial cells formed elongated tubular structures resembling capillary vessels, that appeared to extend towards the tumor spheroids. The tubular structures exhibited complex bifurcations and expanded without adding external angiogenic factors such as VEGF to the culture. To allow high-throughput screening of therapeutic candidates, the 3D cell culture model was successfully miniaturized to a 96-well format, while still maintaining the same level of tumor spheroid growth and vascular sprouting. The quantification of VEGF in the conditioned medium of these cultures showed a continuous increase during the cultivation period, suggesting the contribution of endogenous VEGF to the induction of the angiogenic switch and vascular sprouting. Thus, this model is highly suitable as a testing platform for novel anticancer therapeutics targeting the tumor as well as the vascular compartment.

Raman Imaging and Fluorescence Lifetime Imaging Microscopy for Diagnosis of Cancer State and Metabolic Monitoring

Hurdles for effective tumor therapy are delayed detection and limited effectiveness of systemic drug therapies by patient-specific multidrug resistance. Non-invasive bioimaging tools such as fluorescence lifetime imaging microscopy (FLIM) and Raman-microspectroscopy have evolved over the last decade, providing the potential to be translated into clinics for early-stage disease detection, in vitro drug screening, and drug efficacy studies in personalized medicine. Accessing tissue- and cell-specific spectral signatures, Raman microspectroscopy has emerged as a diagnostic tool to identify precancerous lesions, cancer stages, or cell malignancy. In vivo Raman measurements have been enabled by recent technological advances in Raman endoscopy and signal-enhancing setups such as coherent anti-stokes Raman spectroscopy or surface-enhanced Raman spectroscopy. FLIM enables in situ investigations of metabolic processes such as glycolysis, oxidative stress, or mitochondrial activity by using the autofluorescence of co-enzymes NADH and FAD, which are associated with intrinsic proteins as a direct measure of tumor metabolism, cell death stages and drug efficacy. The combination of non-invasive and molecular-sensitive in situ techniques and advanced 3D tumor models such as patient-derived organoids or microtumors allows the recapitulation of tumor physiology and metabolism in vitro and facilitates the screening for patient-individualized drug treatment options.

Benefits of functional assays in personalized cancer medicine: more than just a proof-of-concept

As complex and heterogeneous diseases, cancers require a more tailored therapeutic management than most pathologies. Recent advances in anticancer drug development, including the immuno-oncology revolution, have been too often plagued by unsatisfying patient response rates and survivals. In reaction to this, cancer care has fully transitioned to the “personalized medicine” concept. Numerous tools are now available tools to better adapt treatments to the profile of each patient. They encompass a large array of diagnostic assays, based on biomarkers relevant to targetable molecular pathways. As a subfamily of such so-called companion diagnostics, chemosensitivity and resistance assays represent an attractive, yet insufficiently understood, approach to individualize treatments. They rely on the assessment of a composite biomarker, the ex vivo functional response of cancer cells to drugs, to predict a patient's outcome. Systemic treatments, such as chemotherapies, as well as targeted treatments, whose efficacy cannot be fully predicted yet by other diagnostic tests, may be assessed through these means. The results can provide helpful information to assist clinicians in their decision-making process. We explore here the most advanced functional assays across oncology indications, with an emphasis on tests already displaying a convincing clinical demonstration. We then recapitulate the main technical obstacles faced by researchers and clinicians to produce more accurate, and thus more predictive, models and the recent advances that have been developed to circumvent them. Finally, we summarize the regulatory and quality frameworks surrounding functional assays to ensure their safe and performant clinical implementation. Functional assays are valuable in vitro diagnostic tools that already stand beyond the “proof-of-concept” stage. Clinical studies show they have a major role to play by themselves but also in conjunction with molecular diagnostics. They now need a final lift to fully integrate the common armament used against cancers, and thus make their way into the clinical routine.

Bioengineering a humanized 3D tri-culture osteosarcoma model to assess tumor invasiveness and therapy response

To date, anticancer therapies with evidenced efficacy in preclinical models fail during clinical trials. The shortage of robust drug screening platforms that accurately predict patient's response underlie these misleading results. To provide a reliable platform for tumor drug discovery, we herein propose a relevant humanized 3D osteosarcoma (OS) model exploring the potential of methacryloyl platelet lysates (PLMA)-based hydrogels to sustain spheroid growth and invasion. The architecture and synergistic cell-microenvironment interaction of an invading tumor was recapitulated encapsulating spheroids in PLMA hydrogels, alone or co-cultured with osteoblasts and mesenchymal stem cells. The stem cells alignment toward OS spheroid suggested that tumor cells chemotactically attracted the surrounding stromal cells, which supported tumor growth and invasion into the hydrogels. The exposure of established models to doxorubicin revealed an improved drug resistance of PLMA-based models, comparing with scaffold-free spheroids. The proposed OS models highlighted the feasibility of PLMA hydrogels to support tumor invasion and recapitulate tumor-stromal cell crosstalk, demonstrating the potential of this 3D platform for complex tumor modelling. STATEMENT OF SIGNIFICANCE: Cell invasion mechanisms involved in tumor progression have been recapitulated in the field of 3D in vitro modeling, leveraging the great advance in biomimetic materials. In line with the growing interest in human-derived biomaterials, the aim of this study is to explore for the first time the potential of methacryloyl platelet lysates (PLMA)-based hydrogels to develop a humanized 3D osteosarcoma model to assess tumor invasiveness and drug sensitivity. By co-culturing tumor spheroids with human osteoblasts and human mesenchymal stem cells, this study demonstrated the importance of the synergistic tumor cell-microenvironment interaction in tumor growth, invasion and drug resistance. The established 3D osteosarcoma model highlighted the feasibility of PLMA hydrogels as a relevant 3D platform for complex tumor modelling.

Bioprinting Technology in Skin, Heart, Pancreas and Cartilage Tissues: Progress and Challenges in Clinical Practice

Bioprinting is an emerging additive manufacturing technique which shows an outstanding potential for shaping customized functional substitutes for tissue engineering. Its introduction into the clinical space in order to replace injured organs could ideally overcome the limitations faced with allografts. Presently, even though there have been years of prolific research in the field, there is a wide gap to bridge in order to bring bioprinting from "bench to bedside". This is due to the fact that bioprinted designs have not yet reached the complexity required for clinical use, nor have clear GMP (good manufacturing practices) rules or precise regulatory guidelines been established. This review provides an overview of some of the most recent and remarkable achievements for skin, heart, pancreas and cartilage bioprinting breakthroughs while highlighting the critical shortcomings for each tissue type which is keeping this technique from becoming widespread reality.

Strategies for active tumor targeting-an update

A complete cure for cancer is still the holy grail for scientists. The existing treatment of cancer is primarily focused on surgery, radiation and conventional chemotherapy. However, chemotherapeutic agents also affect healthy tissues or organs due to a lack of specificity. While passive targeting is studied for anticancer drugs focused on the enhanced permeability and retention effect, it failed to achieve drug accumulation at the tumor site and desired therapeutic efficacy. This review presents an outline of the current significant targets for active tumor drug delivery systems and provides insight into the direction of active tumor-targeting strategies. For this purpose, a systematic understanding of the physiological factors, tumor microenvironment and its components, overexpressed receptor and associated proteins are covered here. We focused on angiogenesis mediated targeting, receptor-mediated targeting and peptide targeting. This active targeting along with integration with nano delivery systems helps in achieving specific action, thus reducing the associated adverse effects to healthy tissues. Although the tumor-targeting methods and possibilities explored so far seem revolutionary in cancer treatment, in-depth clinical studies data is required for its commercial translation.

3D Cancer Models: Depicting Cellular Crosstalk within the Tumour Microenvironment

The tumour microenvironment plays a critical role in tumour progression and drug resistance processes. Non-malignant cell players, such as fibroblasts, endothelial cells, immune cells and others, interact with each other and with the tumour cells, shaping the disease. Though the role of each cell type and cell communication mechanisms have been progressively studied, the complexity of this cellular network and its role in disease mechanism and therapeutic response are still being unveiled. Animal models have been mainly used, as they can represent systemic interactions and conditions, though they face recognized limitations in translational potential due to interspecies differences. In vitro 3D cancer models can surpass these limitations, by incorporating human cells, including patient-derived ones, and allowing a range of experimental designs with precise control of each tumour microenvironment element. We summarize the role of each tumour microenvironment component and review studies proposing 3D co-culture strategies of tumour cells and non-malignant cell components. Moreover, we discuss the potential of these modelling approaches to uncover potential therapeutic targets in the tumour microenvironment and assess therapeutic efficacy, current bottlenecks and perspectives.

Engineering stromal heterogeneity in cancer

Based on our exponentially increasing knowledge of stromal heterogeneity from advances in single-cell technologies, the notion that stromal cell types exist as a spectrum of unique subpopulations that have specific functions and spatial distributions in the tumor microenvironment has significant impact on tumor modeling for drug development and personalized drug testing. In this Review, we discuss the importance of incorporating stromal heterogeneity and tumor architecture, and propose an overall approach to guide the reconstruction of stromal heterogeneity in vitro for tumor modeling. These next-generation tumor models may support the development of more precise drugs targeting specific stromal cell subpopulations, as well as enable improved recapitulation of patient tumors in vitro for personalized drug testing.

Tumor-Penetrable Nitric Oxide-Releasing Nanoparticles Potentiate Local Antimelanoma Therapy

Although nitric oxide (NO) has been emerging as a novel local anticancer agent because of its potent cytotoxic effects and lack of off-target side effects, its clinical applications remain a challenge because of the short effective diffusion distance of NO that limits its anticancer activity. In this study, we synthesized albumin-coated poly(lactic-co-glycolic acid) (PLGA)-conjugated linear polyethylenimine diazeniumdiolate (LP/NO) nanoparticles (Alb-PLP/NO NPs) that possess tumor-penetrating and NO-releasing properties for an effective local treatment of melanoma. Sufficient NO-loading and prolonged NO-releasing characteristics of Alb-PLP/NO NPs were acquired through PLGA-conjugated LP/NO copolymer (PLP/NO) synthesis, followed by nanoparticle fabrication. In addition, tumor penetration ability was rendered by the electrostatic adsorption of the albumin on the surface of the nanoparticles. The Alb-PLP/NO NPs showed enhanced intracellular NO delivery efficiency and cytotoxicity to B16F10 murine melanoma cells. In B16F10-tumor-bearing mice, the Alb-PLP/NO NPs showed improved extracellular matrix penetration and spatial distribution in the tumor tissue after intratumoral injection, resulting in enhanced antitumor activity. Taken together, the results suggest that Alb-PLP/NO NPs represent a promising new modality for the local treatment of melanoma.

A Novel SimpleDrop Chip for 3D Spheroid Formation and Anti-Cancer Drug Assay

Cell culture is important for the rapid screening of anti-cancer drug candidates, attracting intense interest. Traditional 2D cell culture has been widely utilized in cancer biological research. However, 3D cellular spheroids are able to recapitulate the in vivo microenvironment of tissues or tumors. Thus far, several 3D cell culture methods have been developed, for instance, the hanging drop method, spinner flasks and micropatterned plates. Nevertheless, these methods have been reported to have some disadvantages, for example, medium replacement is inconvenient or causes cellular damage. Here, we report on an easy-to-operate and useful micro-hole culture chip (SimpleDrop) for 3D cellular spheroid formation and culture and drug analysis, which has advantages over the traditional method in terms of its ease of operation, lack of shear force and environmentally friendliness. On this chip, we observed the formation of a 3D spheroid clearly. Three drugs (paclitaxel, cisplatin and methotrexate) were tested by both cell viability assay and drug-induced apoptotic assay. The results show that the three drugs present a similar conclusion: cell viability decreased over time and concentration. Moreover, the apoptotic experiment showed a similar trend to the live/dead cell assay, in that the fraction of the apoptotic and necrotic cells correlated with the concentration and time. All these results prove that our SimpleDrop method is a useful and easy method for the formation of 3D cellular spheroids, which shows its potential for both cell-cell interaction research, tissue engineering and anticancer drug screening.

3D Modeling of Epithelial Tumors-The Synergy between Materials Engineering, 3D Bioprinting, High-Content Imaging, and Nanotechnology

The current statistics on cancer show that 90% of all human cancers originate from epithelial cells. Breast and prostate cancer are examples of common tumors of epithelial origin that would benefit from improved drug treatment strategies. About 90% of preclinically approved drugs fail in clinical trials, partially due to the use of too simplified in vitro models and a lack of mimicking the tumor microenvironment in drug efficacy testing. This review focuses on the origin and mechanism of epithelial cancers, followed by experimental models designed to recapitulate the epithelial cancer structure and microenvironment, such as 2D and 3D cell culture models and animal models. A specific focus is put on novel technologies for cell culture of spheroids, organoids, and 3D-printed tissue-like models utilizing biomaterials of natural or synthetic origins. Further emphasis is laid on high-content imaging technologies that are used in the field to visualize in vitro models and their morphology. The associated technological advancements and challenges are also discussed. Finally, the review gives an insight into the potential of exploiting nanotechnological approaches in epithelial cancer research both as tools in tumor modeling and how they can be utilized for the development of nanotherapeutics.

Co-culturing multicellular tumor models: Modeling the tumor microenvironment and analysis techniques

Advances in two-dimensional (2D) and three-dimensional (3D) cell culture over the last 10 years have led to the development of a plethora of methods for cultivating tumor models. More recently, cellular co-cultures have become a suitable testbed. The first portion of this review focuses on co-culturing methods that have been developed in recent years utilizing the multicellular tumor spheroid model. The latter portion describes techniques that are used to analyze the proteomes of mono- or co-cultured tumor models, with a focus on mass spectrometry (MS)-based analyses. Protein profiles are important indicators of the tumor heterogeneity. Therefore, there is a specific focus within this review on analysis by MS and MS imaging methods evaluating the proteomic profiles of 2D and 3D co-cultures. While these models are incredibly important for biological research, so far, they have not been widely explored on the proteomic level. With this review, we aim to introduce these systems to an analytical audience, with the goal of highlighting MS as an underutilized tool for proteomic analysis of tumor models.

Automated evaluation of tumor spheroid behavior in 3D culture using deep learning-based recognition

Three-dimensional in vitro tumor models provide more physiologically relevant responses to drugs than 2D models, but the lack of proper evaluation indices and the laborious quantitation of tumor behavior in 3D have limited the use of 3D tumor models in large-scale preclinical drug screening. Here we propose two indices of 3D tumor invasiveness-the excess perimeter index (EPI) and the multiscale entropy index (MSEI)-and combine these indices with a new convolutional neural network-based algorithm for tumor spheroid boundary detection. This new algorithm for 3D tumor boundary detection and invasiveness analysis is more accurate than any other existing algorithms. We apply this spheroid monitoring and AI-based recognition technique ("SMART") to evaluating the invasiveness of tumor spheroids grown from tumor cell lines and from primary tumor cells in 3D culture.

Validation of a multicellular tumor microenvironment system for modeling patient tumor biology and drug response

Lung cancer rates are rising globally and non-small cell lung cancer (NSCLC) has a five year survival rate of only 24%. Unfortunately, the development of drugs to treat cancer is severely hampered by the inefficiency of translating pre-clinical studies into clinical benefit. Thus, we sought to apply a tumor microenvironment system (TMES) to NSCLC. Using microvascular endothelial cells, lung cancer derived fibroblasts, and NSCLC tumor cells in the presence of in vivo tumor-derived hemodynamic flow and transport, we demonstrate that the TMES generates an in-vivo like biological state and predicts drug response to EGFR inhibitors. Transcriptomic and proteomic profiling indicate that the TMES recapitulates the in vivo and patient molecular biological state providing a mechanistic rationale for the predictive nature of the TMES. This work further validates the TMES for modeling patient tumor biology and drug response indicating utility of the TMES as a predictive tool for drug discovery and development and potential for use as a system for patient avatars.

An Organotypic Mammary Duct Model Capturing Matrix Mechanics-Dependent Ductal Carcinoma In Situ Progression

Ductal carcinoma in situ (DCIS) is a precancerous stage breast cancer, where abnormal cells are contained within the duct, but have not invaded into the surrounding tissue. However, only 30-40% of DCIS cases are likely to progress into an invasive ductal carcinoma (IDC), while the remainder are innocuous. Since little is known about what contributes to the transition from DCIS to IDC, clinicians and patients tend to opt for treatment, leading to concerns of overdiagnosis and overtreatment. In vitro models are currently being used to probe how DCIS transitions into IDC, but many models do not take into consideration the macroscopic tissue architecture and the biomechanical properties of the microenvironment. In this study, we modeled an organotypic mammary duct as a channel molded in a collagen matrix and lined with basement membrane. By adjusting the concentration of collagen (4 and 8 mg/mL), we modulated the stiffness and morphological properties of the matrix and examined how an assortment of breast cells, including the isogenic MCF10 series that spans the range from healthy to aggressive, behaved within our model. We observed distinct characteristics of breast cancer progression such as hyperplasia and invasion. Normal mammary epithelial cells (MCF10A) formed a single-cell layer on the lumen surface, whereas the most aggressive (MCF10CA1) were several cell layers thick. The model captured collagen concentration-dependent protrusive behaviors by the MCF10A and MCF10CA1 cells, as well as a known invasive cell line (MDA-MB-231). The MCF10A and MCF10CA1 cells extended protrusions into the lower collagen concentration matrix, while the MDA-MB-231 cells fully invaded matrices of either collagen concentration but to a greater distance in the higher collagen concentration matrix. Our results show that the model can recapitulate different stages of breast cancer progression and that the MCF10 series is adaptable to physiologically relevant in vitro studies, demonstrating the potential of both the model and cell lines to elucidate key factors that may contribute to understanding the transition from DCIS to IDC. Impact statement The success of early preventative measures for breast cancer has left patients susceptible to overdiagnosis and overtreatment. Limited knowledge of factors driving an invasive transition has inspired the development of in vitro models that accurately capture this phenomenon. However, current models tend to neglect the macroscopic architecture and biomechanical properties of the mammary duct. In this study, we introduce an organotypic model that recapitulates the cylindrical geometry of the tissue and the altered stroma seen in tumor microenvironments. Our model was able to capture distinct features associated with breast cancer progression, demonstrating its potential to uncover novel insights into disease progression.

Blueprint for cancer research: Critical gaps and opportunities

We are experiencing a revolution in cancer. Advances in screening, targeted and immune therapies, big data, computational methodologies, and significant new knowledge of cancer biology are transforming the ways in which we prevent, detect, diagnose, treat, and survive cancer. These advances are enabling durable progress in the goal to achieve personalized cancer care. Despite these gains, more work is needed to develop better tools and strategies to limit cancer as a major health concern. One persistent gap is the inconsistent coordination among researchers and caregivers to implement evidence-based programs that rely on a fuller understanding of the molecular, cellular, and systems biology mechanisms underpinning different types of cancer. Here, the authors integrate conversations with over 90 leading cancer experts to highlight current challenges, encourage a robust and diverse national research portfolio, and capture timely opportunities to advance evidence-based approaches for all patients with cancer and for all communities.

Nanostructured Biomaterials for In Vitro Models of Bone Metastasis Cancer

In recent years, tissue engineering approaches have attracted substantial attention owing to their ability to create physiologically relevant in vitro disease models that closely mimic in vivo conditions. Here, we review nanocomposite materials and scaffolds used for the design of in vitro models of cancer, including metastatic sites. We discuss the role of material properties in modulating cellular phenotype in 3D disease models. Also, we highlight the application of tissue-engineered bone as a tool for faithful recapitulation of the microenvironment of metastatic prostate and breast cancer, since these two types of cancer have the propensity to metastasize to bone. Overall, we summarize recent efforts on developing 3D in vitro models of bone metastatic cancers that provide a platform to study tumor progression and facilitate high-throughput drug screening.

Growth of tumor emboli within a vessel model reveals dependence on the magnitude of mechanical constraint

Tumor emboli-aggregates of tumor cells within vessels-pose a clinical challenge as they are associated with increased metastasis and tumor recurrence. When growing within a vessel, tumor emboli are subject to a unique mechanical constraint provided by the tubular geometry of the vessel. Current models of tumor emboli use unconstrained multicellular tumor spheroids, which neglect this mechanical interplay. Here, we modeled a lymphatic vessel as a 200 μm-diameter channel in either a stiff or soft, bioinert agarose matrix to create a vessel-like constraint model (VLCM), and we modeled colon or breast cancer tumor emboli with aggregates of HCT116 or SUM149PT cells, respectively. The stiff matrix VLCM constrained the tumor emboli to the cylindrical channel, which led to continuous growth of the emboli, in contrast to the growth rate reduction that unconstrained spheroids exhibit. Emboli morphology in the soft matrix VLCM, however, was dependent on the magnitude of mechanical mismatch between the matrix and the cell aggregates. In general, when the elastic modulus of the matrix of the VLCM was greater than the emboli (EVLCM/Eemb > 1), the emboli were constrained to grow within the channel, and when the elastic modulus of the matrix was less than the emboli (0 < EVLCM/Eemb < 1), the emboli bulged into the matrix. Due to a large difference in myosin II expression between the cell lines, we hypothesized that tumor cell aggregate stiffness is an indicator of cellular force-generating capability. Inhibitors of myosin-related force generation decreased the elastic modulus and/or increased the stress relaxation of the tumor cell aggregates, effectively increasing the mechanical mismatch. The increased mechanical mismatch after drug treatment was correlated with increased confinement of tumor emboli growth along the channel, which may translate to increased tumor burden due to the increased tumor volume within the diffusion distance of nutrients and oxygen.

Proteinaceous Hydrogels for Bioengineering Advanced 3D Tumor Models

The establishment of tumor microenvironment using biomimetic in vitro models that recapitulate key tumor hallmarks including the tumor supporting extracellular matrix (ECM) is in high demand for accelerating the discovery and preclinical validation of more effective anticancer therapeutics. To date, ECM-mimetic hydrogels have been widely explored for 3D in vitro disease modeling owing to their bioactive properties that can be further adapted to the biochemical and biophysical properties of native tumors. Gathering on this momentum, herein the current landscape of intrinsically bioactive protein and peptide hydrogels that have been employed for 3D tumor modeling are discussed. Initially, the importance of recreating such microenvironment and the main considerations for generating ECM-mimetic 3D hydrogel in vitro tumor models are showcased. A comprehensive discussion focusing protein, peptide, or hybrid ECM-mimetic platforms employed for modeling cancer cells/stroma cross-talk and for the preclinical evaluation of candidate anticancer therapies is also provided. Further development of tumor-tunable, proteinaceous or peptide 3D microtesting platforms with microenvironment-specific biophysical and biomolecular cues will contribute to better mimic the in vivo scenario, and improve the predictability of preclinical screening of generalized or personalized therapeutics.

Osteosarcoma, personalized medicine, and tissue engineering; an overview of overlapping fields of research

INTRODUCTION

Osteosarcoma is a common bone malignancy in patients of all ages. Surgical and chemotherapy interventions fail to shrink tumor growth and metastasis. The development of efficient patient-specific therapeutic strategies for osteosarcoma is of great interest in tissue engineering and personalized medicine. The present manuscript aimed to review the advancements in tissue engineering and personalized medicine strategies to overcome osteosarcoma and the relevant biological aspects as well as the current tumor models in vitro and in vivo.

RESULTS

Tissue engineering and personalized medicine contribute to gene/cell engineering and cell-based therapies specific to genomic and proteomic profiles of individual patients to improve the current treatment options. Also, tissue engineering scaffolds provide physical support to missing bones, could trap cancer cells and deliver immune cells. Taken together, these strategies suppress tumor growth, angiogenic potential, and the subsequent metastasis as well as elicit desirable immune responses against tumor mass.

DISCUSSION

Advanced and high-throughput gene and protein identification technologies have facilitated the recognition of genomic and proteomic profiles of patients to design and develop patient-specific treatments. The pre-clinical studies showed promising outcomes to inhibit tumor growth and invasion but controversial results compared to clinical investigations make the importance of more clinical reports inevitable. The experimental tumor models assist the evolution of effective treatments by understanding the mechanisms of tumor progression.

CONCLUSION

Tissue engineering and personalized medicine strategies seem encouraging alternatives to conventional therapies against osteosarcoma. Modeling the tumor microenvironment coupled with pre-clinical results give new intelligence into the translation of strategies into the clinic.

Lung organoids: advances in generation and 3D-visualization

The lung is comprised of more than 40 distinct cell types that support a complex 3-dimensional (3D) architecture that is required for efficient lung function. Loss of this proper architecture can accommodate and promote lung disease, highlighting researchers' growing need to analyze lung structures in detail. Additionally, in vivo cellular and molecular response to chemical and physical signals, along with the recapitulation of gene-expression patterns, can be lost during the transition from complex 3D tissues to 2D cell culture systems. Therefore, technologies that allow for the investigation of lung function under normal and disease states utilizing the entirety of the lung architecture are required to generate a complete understanding of these processes. Airway cell-derived organoids that can recapitulate lung structure and function ex vivo while being amenable to experimental manipulation, have provided a new and exciting model system to investigate lung biology. In this perspective, we discuss emerging technologies for culturing lung-derived organoids, techniques to visualize organoids using high-resolution microscopy and the resulting information extracted from organoids supporting research focused on lung function and diseases.