A three-dimensional engineered heterogeneous tumor model for assessing cellular environment and response

Mini-MEndR: a miniaturized 96-well predictive assay to evaluate muscle stem cell-mediated repair

Background

Functional evaluation of molecules that are predicted to promote stem cell mediated endogenous repair often requires in vivo transplant studies that are low throughput and hinder the rate of discovery. To offer greater throughput for functional validation studies, we miniaturized, simplified and expanded the functionality of a previously developed muscle endogenous repair (MEndR) in vitro assay that was shown to capture significant events of in vivo muscle endogenous repair.

Methods

The mini-MEndR assay consists of miniaturized cellulose scaffolds designed to fit in 96-well plates, the pores of which are infiltrated with human myoblasts encapsulated in a fibrin-based hydrogel to form engineered skeletal muscle tissues. Pre-adsorbing thrombin to the cellulose scaffolds facilitates in situ tissue polymerization, a critical modification that enables new users to rapidly acquire assay expertise. Following the generation of the 3D myotube template, muscle stem cells (MuSCs), enriched from digested mouse skeletal muscle tissue using an improved magnetic-activated cell sorting protocol, are engrafted within the engineered template. Murine MuSCs are fluorescently labeled, enabling co-evaluation of human and mouse Pax7+ cell responses to drug treatments. A regenerative milieu is introduced by injuring the muscle tissue with a myotoxin to initiate endogenous repair "in a dish". Phenotypic data is collected at endpoints with a high-content imaging system and is analyzed using ImageJ-based image analysis pipelines.

Results

The miniaturized format and modified manufacturing protocol cuts reagent costs in half and hands-on seeding time ~ threefold, while the image analysis pipelines save 40 h of labour. By evaluating multiple commercially available human primary myoblast lines in 2D and 3D culture, we establish quality assurance metrics for cell line selection that standardizes myotube template quality. In vivo outcomes (enhanced muscle production and Pax7+ cell expansion) to a known modulator of MuSC mediated repair (p38/β MAPK inhibition) are recapitulated in the miniaturized culture assay, but only in the presence of stem cells and the regenerative milieu.

Discussion

The miniaturized predictive assay offers a simple, scaled platform to co-investigate human and mouse skeletal muscle endogenous repair molecular modulators, and thus is a promising strategy to accelerate the muscle endogenous repair discovery pipeline.

Supplementary Information

The online version contains supplementary material available at 10.1186/s44330-024-00005-4.

3D Models of Sarcomas: The Next-generation Tool for Personalized Medicine

Sarcoma is a complex and heterogeneous cancer that has been difficult to study in vitro. While two-dimensional (2D) cell cultures and mouse models have been the dominant research tools, three-dimensional (3D) culture systems such as organoids have emerged as promising alternatives. In this review, we discuss recent developments in sarcoma organoid culture, with a focus on their potential as tools for drug screening and biobanking. We also highlight the ways in which sarcoma organoids have been used to investigate the mechanisms of gene regulation, drug resistance, metastasis, and immune interactions. Sarcoma organoids have shown to retain characteristics of in vivo biology within an in vitro system, making them a more representative model for sarcoma research. Our review suggests that sarcoma organoids offer a potential path forward for translational research in this field and may provide a platform for developing personalized therapies for sarcoma patients.

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.

An Integrative Bioorthogonal Nanoengineering Strategy for Dynamically Constructing Heterogenous Tumor Spheroids

Although tumor models have revolutionized perspectives on cancer aetiology and treatment, current cell culture methods remain challenges in constructing organotypic tumor with in vivo-like complexity, especially native characteristics, leading to unpredictable results for in vivo responses. Herein, the bioorthogonal nanoengineering strategy (BONE) for building photothermal dynamic tumor spheroids is developed. In this process, biosynthetic machinery incorporated bioorthogonal azide reporters into cell surface glycoconjugates, followed by reacting with multivalent click ligand (ClickRod) that is composed of hyaluronic acid-functionalized gold nanorod carrying dibenzocyclooctyne moieties, resulting in rapid construction of tumor spheroids. BONE can effectively assemble different cancer cells and immune cells together to construct heterogenous tumor spheroids is identified. Particularly, ClickRod exhibited favorable photothermal activity, which precisely promoted cell activity and shaped physiological microenvironment, leading to formation of dynamic features of original tumor, such as heterogeneous cell population and pluripotency, different maturation levels, and physiological gradients. Importantly, BONE not only offered a promising platform for investigating tumorigenesis and therapeutic response, but also improved establishment of subcutaneous xenograft model under mild photo-stimulation, thereby significantly advancing cancer research. Therefore, the first bioorthogonal nanoengineering strategy for developing dynamic tumor models, which have the potential for bridging gaps between in vitro and in vivo research is presented.

Scaffold-Free Multicellular 3D Tissue Constructs Utilizing Bio-orthogonal Click Strategy

Multicellular 3D tissue constructs (MTCs) are important in biomedical research due to their capacity to accurately mimic the structure and variation found in real tissues. This study presents a novel bio-orthogonal engineering strategy (BIEN), a transformative scaffold-free approach, to create advanced MTCs. BIEN harnesses the cellular biosynthetic machinery to incorporate bio-orthogonal azide reporters into cell surface glycoconjugates, followed by a click reaction with multiarm PEG, resulting in rapid assembly of MTCs. The implementation of this cutting-edge strategy culminates in the formation of uniform, heterogeneous spheroids, characterized by a high degree of intercellular junction and pluripotency. Remarkably, MTCs simulate tumor features, ensure cell heterogeneity, and significantly improve the subcutaneous xenograft model after transplantation, thereby bolstering both in vitro and in vivo research models. In conclusion, the utilization of the bio-orthogonal engineering strategy as a scaffold-free method to generate superior MTCs holds promising potential for driving advancements in cancer research.

A novel method to investigate drug resistance in the chronic lymphocytic leukemia (CLL) microenvironment: Analysis of CLL Cellular Environment and Response (ACCER)

Microenvironments such as lymph nodes allow chronic lymphocytic leukemia (CLL) cells to survive and become drug resistant. There are limited methods to study the to study the contribution of the stromal microenvironment. We have adapted a solid tumor microenvironment cell culture system that provides elements of the CLL microenvironment called Analysis of CLL Cellular Environment and Response (ACCER). We optimized the cell number for patient's primary CLL cells and HS-5 human bone marrow stromal cell line that will give sufficient cell number and viability with the ACCER. We then determined the amount of collagen type 1 to give the best extracellular matrix to seed CLL cells to the membrane. Finally, we determined that ACCER provide CLL cell protection against cell death following treatment with fludarabine and ibrutinib compared to co-culture conditions. This describes novel microenvironment model to investigate factors that promote drug resistance in CLL.

Advances in the application of 3D tumor models in precision oncology and drug screening

Traditional tumor models cannot perfectly simulate the real state of tumors in vivo, resulting in the termination of many clinical trials. 3D tumor models’ technology provides new in vitro models that bridge the gap between in vitro and in vivo findings, and organoids maintain the properties of the original tissue over a long period of culture, which enables extensive research in this area. In addition, they can be used as a substitute for animal and in vitro models, and organoids can be established from patients’ normal and malignant tissues, with unique advantages in clinical drug development and in guiding individualized therapies. 3D tumor models also provide a promising platform for high-throughput research, drug and toxicity testing, disease modeling, and regenerative medicine. This report summarizes the 3D tumor model, including evidence regarding the 3D tumor cell culture model, 3D tumor slice model, and organoid culture model. In addition, it provides evidence regarding the application of 3D tumor organoid models in precision oncology and drug screening. The aim of this report is to elucidate the value of 3D tumor models in cancer research and provide a preclinical reference for the precise treatment of cancer patients.

A three-dimensional human adipocyte model of fatty acid-induced obesity

Obesity prevalence has reached pandemic proportions, leaving individuals at high risk for the development of diseases such as cancer and type 2 diabetes. In obesity, to accommodate excess lipid storage, adipocytes become hypertrophic, which is associated with an increased pro-inflammatory cytokine secretion and dysfunction of metabolic processes such as insulin signaling and lipolysis. Targeting adipocyte dysfunction is an important strategy to prevent the development of obesity-associated disease. However, it is unclear how accurately animal models reflect human biology, and the long-term culture of human hypertrophic adipocytes in an in vitro 2D monolayer is challenging due to the buoyant nature of adipocytes. Here we describe the development of a human 3D in vitro disease model that recapitulates hallmarks of obese adipocyte dysfunction. First, primary human adipose-derived mesenchymal stromal cells are embedded in hydrogel, and infiltrated into a thin cellulose scaffold. The thin microtissue profile allows for efficient assembly and image-based analysis. After adipocyte differentiation, the scaffold is stimulated with oleic or palmitic acid to mimic caloric overload. Using functional assays, we demonstrated that this treatment induced important obese adipocyte characteristics such as a larger lipid droplet size, increased basal lipolysis, insulin resistance and a change in macrophage gene expression through adipocyte-conditioned media. This 3D disease model mimics physiologically relevant hallmarks of obese adipocytes, to enable investigations into the mechanisms by which dysfunctional adipocytes contribute to disease.

Monitoring and modulation of the tumor microenvironment for enhanced cancer modeling

Cancer treatments utilizing biologic or cytotoxic drugs compose the frontline of therapy, and though gains in treatment efficacy have been persistent in recent decades, much work remains in understanding cancer progression and treatment. Compounding this situation is the low rate of success when translating preclinical drug candidates to the clinic, which raises costs and development timelines. This underperformance is due in part to the poor recapitulation of the tumor microenvironment, a critical component of cancer biology, in cancer model systems. New technologies capable of both accurately observing and manipulating the tumor microenvironment are needed to effectively model cancer response to treatment. In this review, conventional cancer models are summarized, and a primer on emerging techniques for monitoring and modulating the tumor microenvironment is presented and discussed.

Natural Killer Cells: the Missing Link in Effective Treatment for High-Grade Serous Ovarian Carcinoma

OPINION STATEMENT

Ovarian cancer (OC), especially high-grade serous cancer (HGSC), is a highly heterogeneous malignancy with limited options for curative treatment and a high frequency of relapse. Interactions between OC and the immune system may permit immunoediting and immune escape, and current standard of care therapies can influence immune cell infiltration and function within the tumor microenvironment. Natural killer (NK) cells are involved in cancer immunosurveillance and immunoediting and can be activated by therapy, but deliberate approaches to maximize NK cell reactivity for treatment of HGSC are in their infancy. NK cells may be the ideal target for immunotherapy of HGSC. The diverse functions of NK cells, and their established roles in immunosurveillance, make them attractive candidates for more precise and effective HGSC treatment. NK cells' functional capabilities differ because of variation in receptor expression and genetics, with meaningful impacts on their anticancer activity. Studying HGSC:NK cell interactions will define the features that predict the best outcomes for patients with the disease, but the highly diverse nature of HGSC will likely require combination therapies or approaches to simultaneously target multiple, co-existing features of the tumor to avoid tumor escape and relapse. We expect that the ideal therapy will enable NK cell infiltration and activity, reverse immunosuppression within the tumor microenvironment, and enable effector functions against the diverse subpopulations that comprise HGSC.

Spontaneous formation and spatial self-organization of mechanically induced mesenchymal-like cells within geometrically confined cancer cell monolayers

There is spatiotemporal heterogeneity in cell phenotypes and mechanical properties in tumor tissues, which is associated with cancer invasion and metastasis. It is well-known that exogenous growth factors like transforming growth factor (TGF)-β, can induce epithelial-mesenchymal transition (EMT)-based phenotypic transformation and the formation of EMT patterning on geometrically confined monolayers with mechanics heterogeneity. In the absence of exogenous TGF-β stimulation, however, whether geometric confinement-caused mechanics heterogeneity of cancer cell monolayers alone can trigger the EMT-based phenotypic heterogeneity still remains mysterious. Here, we develop a micropattern-based cell monolayer model to investigate the regulation of mechanics heterogeneity on the cell phenotypic switch. We reveal that mechanics heterogeneity itself is enough to spontaneously induce the emergence of mesenchymal-like phenotype and asymmetrical activation of TGF-β-SMAD signaling. Spatiotemporal dynamics of patterned cell monolayers with mesenchymal-like phenotypes is essentially regulated by tissue-scale cell behaviors like proliferation, migration as well as heterogeneous cytoskeletal contraction. The inhibition of cell contraction abrogates the asymmetrical TGF-β-SMAD signaling activation level and the emergence of mesenchymal-like phenotype. Our work not only sheds light on the key regulation of mechanics heterogeneity caused by spatially geometric confinement on regional mesenchymal-like phenotype of cancer cell monolayers, but highlights the key role of biophysical/mechanical cues in triggering phenotypic switch.

Organotypic 3D decellularized matrix tumor spheroids for high-throughput drug screening

Decellularized extracellular matrix (dECM) is emerging as a valuable tool for generating 3D in vitro tumor models that better recapitulate tumor-stroma interactions. However, the development of dECM-3D heterotypic microtumors exhibiting a controlled morphology is yet to be materialized. Precisely controlling microtumors morphologic features is key to avoid an inaccurate evaluation of therapeutics performance during preclinical screening. To address this, herein we employed ultra-low adhesion surfaces for bioengineering organotypic 3D metastatic breast cancer-fibroblast models enriched with dECM microfibrillar fragments, as a bottom-up strategy to include major matrix components and their associated biomolecular cues during the early stages of 3D microtissue spheroids assembly, simulating pre-existing ECM presence in the in vivo setting. This biomimetic approach enabled the self-assembly of dECM-3D tumor-stroma spheroids with tunable size and reproducible morphology. Along time, dECM enriched and stroma-rich microtumors exhibited necrotic core formation, secretion of key biomarkers and higher cancer-cell specific resistance to different chemotherapeutics in comparison to standard spheroids. Exometabolomics profiling of dECM-Spheroid in vitro models further identified important breast cancer metabolic features including glucose/pyruvate consumption and lactate excretion, which suggest an intense glycolytic activity, recapitulating major hallmarks of the native microenvironment. Such organotypic dECM-enriched microtumors overcome the morphologic variability generally associated with cell-laden dECM models, while providing a scalable testing platform that can be foreseeable leveraged for high-throughput screening of candidate therapeutics.

Cryopreservable arrays of paper-based 3D tumor models for high throughput drug screening

Three-dimensional (3D) tumor models have gained increased attention in life-science applications as they better represent physiological conditions of in vivo tumor microenvironments, and thus, possess big potential for guiding drug screening studies. Although various techniques proved effective in growing cancer cells in 3D, their procedures are typically complex, time consuming, and expensive. Here, we present a versatile, robust, and cost-effective method that utilizes a paper platform to create cryopreservable high throughput arrays of 3D tumor models. In the approach, we use custom 3D printed masks along with simple chemistry modifications to engineer highly localized hydrophilic 'virtual microwells', or microspots, on paper for 3D cell aggregation, surrounded by hydrophobic barriers that prevent inter-microspot mixing. The method supports the formation and cryopreservation of 3D tumor arrays for extended periods of storage time. Using MCF-7 and MDA-MB-231 breast cancer cell lines, we show that the cryopreservable arrays of paper-based 3D models are effective in studying tumor response to cisplatin drug treatment, while replicating key characteristics of the in vivo tumors that are absent in conventional 2D cultures. This technology offers a low cost, easy, and fast experimental procedure, and allows for 3D tumor arrays to be cryopreserved and thawed for on-demand use. This could potentially provide unparalleled advantages to the fields of tissue engineering and personalized medicine.

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

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

Evaluation of inhibitory effects of geniposide on a tumor model of human breast cancer based on 3D printed Cs/Gel hybrid scaffold

Traditional Chinese medicine therapy, which can serve as adjuvant therapy for cancer treatment, has no obvious side effects on the human body. Geniposide (GEN), one of the main iridoid glycosides in gardenia fruit, has been widely reported to have anti-cancer effects. In this study, we aimed to inspect whether GEN could inhibit proliferation and promote the apoptosis of human breast cancer cells (MCF-7). In order to better predict the efficacy of GEN, we have prepared the Cs/Gel composite scaffolds by 3D printing technology to mimic the MCF-7 cell growth microenvironment. The prepared Cs/Gel scaffold has good mechanical properties and biocompatibility, which can provide a more accurate platform for drug screening. The semi-inhibitory concentration (IC50) evaluated by CCK-8 assay was 16.06 mg/mL (24 h), 14.85 mg/mL (48 h), and 13.14 mg/mL (72 h). After exposed to GEN for 48 h, the cancer cell survival rate reduced from 69.15 ± 2.86% (13 mg/mL) to 20.97 ± 3.24% (16 mg/mL). Although the inhibitory effect was weaker in the 3D culture system, it also managed to inhibit cell proliferation and induce cell apoptosis. Besides, Live/Dead staining, Hematoxylin-Eosin (H&E) staining and SEM evaluation were also conducted to estimate the anti-cancer effect of GEN in 2D and 3D cultures. The results indicate that GEN has an anti-cancer effect based on a time- and dose-dependent manner.

A TRACER culture invasion assay to probe the impact of cancer associated fibroblasts on head and neck squamous cell carcinoma cell invasiveness

Cancer associated fibroblasts (CAFs) are a major cellular component of the tumour stroma and have been shown to promote tumour cell invasion and disease progression. CAF-cancer cell interactions are bi-directional and occur via both soluble factor dependent and extracellular matrix (ECM) remodelling mechanisms, which are incompletely understood. Previously we developed the Tissue Roll for Analysis of Cellular Environment and Response (TRACER), a novel stacked paper tumour model in which cells embedded in a hydrogel are infiltrated into a porous cellulose scaffold that is then rolled around an aluminum core to generate a multi-layered 3D tissue. Here, we use the TRACER platform to explore the impact of CAFs derived from three different patients on the invasion of two head and neck squamous cell carcinoma (HNSCC) cell lines (CAL33 and FaDu). We find that co-culture with CAFs enhances HNSCC tumour cell invasion into an acellular collagen layer in TRACER and this enhanced migration occurs independently of proliferation. We show that CAF-enhanced invasion of CAL33 cells is driven by a soluble factor independent mechanism, likely involving CAF mediated ECM remodelling via matrix metalloprotenases (MMPs). Furthermore, we find that CAF-enhanced tumour cell invasion is dependent on the spatial pattern of collagen density within the culture. Our results highlight the utility of the co-culture TRACER platform to explore soluble factor independent interactions between CAFs and tumour cells that drive increased tumour cell invasion.

A one-step tannic acid coating to improve cell adhesion and proliferation on polydimethylsiloxane

A green and straightforward tannic acid functionalization can enhance cell adhesion and proliferation on PDMS, and thus, can be potentially used for microfluidic cell assay devices for cellular physiological study or drug screening.

PLLA scaffolds with controlled architecture as potential microenvironment for in vitro tumor model

The "microenvironment" where a tumor develops plays a fundamental role in determining its progression, the onset of metastasis and, eventually, its resistance to therapies. Tumor cells can be considered more or less invasive depending both on the nature of the cells and on the site where they are located. Commonly adopted laboratory culture protocols for the investigation of tumor cells take usually place on standard two-dimensional supports. However, such cultures do not allow for reproduction of the biophysical properties of the tumor's microenvironment, thus causing the cells to lose most of their relevant characteristics. In this work MDA-MB 231 breast cancer cells were cultivated within Poly-l-Lactic Acid (PLLA) scaffolds produced via Thermally Induced Phase Separation (TIPS). Starting from a ternary solution (polymer-solvent-nonsolvent) we produced scaffolds with different morphologies, porosities and pore architectures. The influence of porosity and average pore size upon cell adhesion and growth were investigated by using Cell Counting Kit-8 (CCK-8) as cell viability test, a fluorescence assay staining cell with DAPI and Scanning Electron Microscopy (SEM). Our study demonstrates that the average pore size of the polymeric scaffolds influences both the cell adhesion and resulting morphology of the growing breast cancer cells. In particular, the reported data corroborate the evidence that an average pore size ranging from 40 to 50 μm induces tumor cell aggregation and the formation of the irregular tumor masses typically observed in-vivo. In addition, TIPS proved to be a suitable manufacturing technique for finely tuning the scaffolds' architecture, relevant to developing the most effective microenvironment for an in-vitro tumor cells growth closely mimicking in-vivo conditions.