Mechanobiology of cancer cell responsiveness to chemotherapy and immunotherapy: Mechanistic insights and biomaterial platforms

Mechanical forces are central to how cancer treatments such as chemotherapeutics and immunotherapies interact with cells and tissues. At the simplest level, electrostatic forces underlie the binding events that are critical to therapeutic function. However, a growing body of literature points to mechanical factors that also affect whether a drug or an immune cell can reach a target, and to interactions between a cell and its environment affecting therapeutic efficacy. These factors affect cell processes ranging from cytoskeletal and extracellular matrix remodeling to transduction of signals by the nucleus to metastasis of cells. This review presents and critiques the state of the art of our understanding of how mechanobiology impacts drug and immunotherapy resistance and responsiveness, and of the in vitro systems that have been of value in the discovery of these effects.

Dynamic modulation and epoxy functionalization of protein-mediated enoate ester-based hybrid cryogels

The current work is focused on the preparation of protein-mediated poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) copolymer as a self-template for in situ synthesis of hybrid gels. Gelatin, collagen, biotin, and l-arginine were used to create hybrid materials with adjustable swelling and elastic properties. Hybrid cryogels tended to swell more than hybrid hydrogels due to their porous nature. Collaged-doped cryogels had the highest swelling, whereas gelatin-doped hybrids showed enhanced elastic modulus. All hybrid gels exhibited pH-sensitive swelling to controlled release applications depending on the degree of protonation of NH₂ and COOH groups in the side chains. At low pH conditions, hybrid cryogels exhibited a higher swelling tendency compared to hydrogels. Ion-stimulus-response of hybrid gels was studied to evaluate the effect of salt concentration and features of ambient ions on swelling. Depending on the polyelectrolytic or polyampholytic nature, the extent of swelling in NaCl and KCl solutions varied according to the charge distribution in the network chains. Hybrid gels showed excellent adsorption performance for methyl orange by the presence of epoxy, hydroxyl groups, amino and carboxyl groups providing sufficient active sites. Adsorption capacity of hybrid cryogels is higher than that of hydrogels. The removal rate 97/%, reached an equilibrium state in a short period, suggested that collagen-doped hybrid cryogels have a potential application to remove dyestuff from wastewater. In relation to the decrease of methyl orange concentration in solution, adsorption process followed pseudo-second-order kinetic model. Avrami model has provided a better experimental-calculated fit and adsorption thermodynamics analysis indicated that the adsorption was a spontaneous process with a negative standard free energy. The characteristic findings from this research will provide insights into the design and application of enoate-ester and protein-based combinations in the food, biomedical and cosmetic fields.

Recent Developments in Cell Shipping Methods

As opposed to remarkable advances in the cell therapy industry, researches reveal inexplicable difficulties associated with preserving and post-thawing cell death. Post cryopreservation apoptosis is a common occurrence that has attracted the attention of scientists to use apoptosis inhibitors. Transporting cells without compromising their survival and function is crucial for any experimental cell-based therapy. Preservation of cells allows the safe transportation of cells between distances and improves quality control testing in clinical and research applications. The vitality of transported cells is used to evaluate the efficacy of transportation strategies. For many decades, the conventional global methods of cell transfer were not only expensive but also challenging and had adverse effects. The first determination of some projects is optimizing cell survival after cryopreservation. The new generation of cryopreservation science wishes to find appropriate and alternative methods for cell transportation to ship viable cells at an ambient temperature without dry ice or in media-filled flasks. The diversity of cell therapies demands new cell shipping methodologies and cryoprotectants. In this review, we tried to summarize novel improved cryopreservation methods and alternatives to cryopreservation with safe and viable cell shipping at ambient temperature, including dry preservation, hypothermic preservation, gel-based methods, encapsulation methods, fibrin microbeads, and osmolyte solution compositions. This article is protected by copyright. All rights reserved.

An Overview on Collagen and Gelatin-Based Cryogels: Fabrication, Classification, Properties and Biomedical Applications

Decades of research into cryogels have resulted in the development of many types of cryogels for various applications. Collagen and gelatin possess nontoxicity, intrinsic gel-forming ability and physicochemical properties, and excellent biocompatibility and biodegradability, making them very desirable candidates for the fabrication of cryogels. Collagen-based cryogels (CBCs) and gelatin-based cryogels (GBCs) have been successfully applied as three-dimensional substrates for cell culture and have shown promise for biomedical use. A key point in the development of CBCs and GBCs is the quantitative and precise characterization of their properties and their correlation with preparation process and parameters, enabling these cryogels to be tuned to match engineering requirements. Great efforts have been devoted to fabricating these types of cryogels and exploring their potential biomedical application. However, to the best of our knowledge, no comprehensive overviews focused on CBCs and GBCs have been reported currently. In this review, we attempt to provide insight into the recent advances on such kinds of cryogels, including their fabrication methods and structural properties, as well as potential biomedical applications.

Recapitulating Tumorigenesis in vitro: Opportunities and Challenges of 3D Bioprinting

Cancer is considered one of the most predominant diseases in the world and one of the principal causes of mortality per year. The cellular and molecular mechanisms involved in the development and establishment of solid tumors can be defined as tumorigenesis. Recent technological advances in the 3D cell culture field have enabled the recapitulation of tumorigenesis in vitro, including the complexity of stromal microenvironment. The establishment of these 3D solid tumor models has a crucial role in personalized medicine and drug discovery. Recently, spheroids and organoids are being largely explored as 3D solid tumor models for recreating tumorigenesis in vitro. In spheroids, the solid tumor can be recreated from cancer cells, cancer stem cells, stromal and immune cell lineages. Organoids must be derived from tumor biopsies, including cancer and cancer stem cells. Both models are considered as a suitable model for drug assessment and high-throughput screening. The main advantages of 3D bioprinting are its ability to engineer complex and controllable 3D tissue models in a higher resolution. Although 3D bioprinting represents a promising technology, main challenges need to be addressed to improve the results in cancer research. The aim of this review is to explore (1) the principal cell components and extracellular matrix composition of solid tumor microenvironment; (2) the recapitulation of tumorigenesis in vitro using spheroids and organoids as 3D culture models; and (3) the opportunities, challenges, and applications of 3D bioprinting in this area.

The Implementation of the Three Rs in Regulatory Toxicity and Biosafety Assessment: The Indian Perspective

Animal models have long served as a basis for scientific experimentation, biomedical research, drug development and testing, disease modelling and toxicity studies, as they are widely thought to provide meaningful, human-relevant predictions. However, many of these systems are resource intensive and time-consuming, have low predictive value and are associated with great social and ethical dilemmas. Often drugs appear to be effective and safe in these classical animal models, but later prove to be ineffective and/or unsafe in clinical trials. These issues have paved the way for a paradigm shift from the use of in vivo approaches, toward the 'science of alternatives'. This has fuelled several research and regulatory initiatives, including the ban on the testing of cosmetics on animals. The new paradigm has been shifted toward increasing the relevance of the models for human predictivity and translational efficacy, and this has resulted in the recent development of many new methodologies, from 3-D bio-organoids to bioengineered 'human-on-a-chip' models. These improvements have the potential to significantly advance medical research globally. This paper offers a stance on the existing strategies and practices that utilise alternatives to animals, and outlines progress on the incorporation of these models into basic and applied research and education, specifically in India. It also seeks to provide a strategic roadmap to streamline the future directions for the country's policy changes and investments. This strategic roadmap could be a useful resource to guide research institutions, industries, regulatory agencies, contract research organisations and other stakeholders in transitioning toward modern approaches to safety and risk assessment that could replace or reduce the use of animals without compromising the safety of humans or the environment.

Recent Advances in Biomaterial-Based High-Throughput Platforms

High-throughput systems allow screening and analysis of large number of samples simultaneously under same conditions. Over recent years, high-throughput systems have found applications in fields other than drug discovery like bioprocess industries, pollutant detection, material microarrays, etc. With the introduction of materials in such HT platforms, the screening system has been enabled for solid phases apart from conventional solution phase. The use of biomaterials has further facilitated cell-based assays in such platforms. Here, the authors have focused on the recent developments in biomaterial-based platforms including the fabricationusing contact and non-contact methods and utilization of such platforms for discovery of novel biomaterials exploiting interaction of biological entities with surface and bulk properties. Finally, the authors have elaborated on the application of the biomaterial-based high-throughput platforms in tissue engineering and regenerative medicine, cancer and stem cell studies. The studies show encouraging applications of biomaterial microarrays. However, success in clinical applicability still seems to be a far off task majorly due to absence of robust characterization and analysis techniques. Extensive focus is required for developing personalized medicine, analytical tools and storage/shelf-life of cell laden microarrays.

Gelatin interpenetration in poly N-isopropylacrylamide network reduces the compressive modulus of the scaffold: A property employed to mimic hepatic matrix stiffness

The progression of liver disease from normal to cirrhotic state is characterized by modulation of the stiffness of the extracellular matrix (ECM). Mimicking this modulation in vitro scaffold could provide a better insight into hepatic cell behavior. In this study, interpenetrating poly(N-isopropylacrylamide-co-gelatin) cryogels were synthesized in 48 different compositions to yield scaffolds of different properties. It was observed that a high concentration of N-isopropylacrylamide (NIPAAm) leads to the formation of small pores while gelatin interpenetration on poly-NIPAAm framework renders porous structure. Swelling properties and porosity of the gels decreased with an increase in NIPAAm concentration owing to the increased compactness of the gels. Gelatin interpenetration relaxed the gels and enhanced these properties. An increase in gelatin concentration led to a reduction in compressive moduli indicating that gelatin interpenetration in the poly-NIPAAm network softens the cryogel. With the increase in NIPAAm concentration, the effect of gelatin interpenetration in reducing the compressive moduli expanded. The cytocompatibility studies indicated that the gels are cell-adherent and compatible with HepG2. Furthermore, biochemical and real-time polymerase chain reaction studies revealed that HepG2 and Huh-7 cells cultured on scaffolds mimicking the ECM stiffness of normal liver (1.5-2.5 kPa) exhibited optimum liver-specific functionalities. Increasing the stiffness to fibrotic (4-9 kPa) and cirrhotic (10-20 kPa) ECM decreases the functionality.

Three-dimensional cryogel matrix for spheroid formation and anti-cancer drug screening

Spheroid-based systems have been developed as alternatives to two-dimensional (2D) monolayer cultures for understanding 3D cell behavior and conducting in vitro drug screening tests. However, spheroids are easily disrupted while handling and do not mimic the presence of extracellular matrix (ECM) components. To address that, we have developed a cost-effective, polyethylene glycol diacrylate (PEGDA), and gelatin methacryloyl (GELMA) based semi-synthetic cryogel matrix system, which can be used to grow spheroids and conduct studies while providing architectural support and mimicking in vivo ECM components. These matrices are macroporous and support formation of tumor-like spheroids of breast tumor epithelial (MCF-7) cells in the absence of additional growth factors otherwise required for spheroid formation. Difference in morphology of cells as a function of matrix composition and increase in size and number of spheroids as a function of time was observed. Spheroids grown in cryogel matrices showed more drug resistance than their 2D counterparts, which can partially be explained by the epithelial to mesenchymal transition (EMT) observed in spheroids. We believe that spheroids formed through these PEGDA-GELMA cryogel matrices better represent in vivo pathological conditions and can help develop cost-effective in vitro assays for screening new pharmacological drug candidates and performing cell mechanistic studies.

Applicability of drug response metrics for cancer studies using biomaterials

Bioengineers have built models of the tumour microenvironment (TME) in which to study cell-cell interactions, mechanisms of cancer growth and metastasis, and to test new therapies. These models allow researchers to culture cells in conditions that include features of the in vivo TME implicated in regulating cancer progression, such as extracellular matrix (ECM) stiffness, integrin binding to the ECM, immune and stromal cells, growth factor and cytokine depots, and a three-dimensional geometry more representative of the in vivo TME than tissue culture polystyrene (TCPS). These biomaterials could be particularly useful for drug screening applications to make better predictions of efficacy, offering better translation to preclinical models and clinical trials. However, it can be challenging to compare drug response reports across different biomaterial platforms in the current literature. This is, in part, a result of inconsistent reporting and improper use of drug response metrics, and vast differences in cell growth rates across a large variety of biomaterial designs. This study attempts to clarify the definitions of drug response measurements used in the field, and presents examples in which these measurements can and cannot be applied. We suggest as best practice to measure the growth rate of cells in the absence of drug, and follow our 'decision tree' when reporting drug response metrics. This article is part of a discussion meeting issue 'Forces in cancer: interdisciplinary approaches in tumour mechanobiology'.

Fluid shear stress stimulates breast cancer cells to display invasive and chemoresistant phenotypes while upregulating PLAU in a 3D bioreactor

Breast cancer cells experience a range of shear stresses in the tumor microenvironment (TME). However most current in vitro three-dimensional (3D) models fail to systematically probe the effects of this biophysical stimuli on cancer cell metastasis, proliferation, and chemoresistance. To investigate the roles of shear stress within the mammary and lung pleural effusion TME, a bioreactor capable of applying shear stress to cells within a 3D extracellular matrix was designed and characterized. Breast cancer cells were encapsulated within an interpenetrating network hydrogel and subjected to shear stress of 5.4 dynes cm^-2 for 72 hr. Finite element modeling assessed shear stress profiles within the bioreactor. Cells exposed to shear stress had significantly higher cellular area and significantly lower circularity, indicating a motile phenotype. Stimulated cells were more proliferative than static controls and showed higher rates of chemoresistance to the anti-neoplastic drug paclitaxel. Fluid shear stress-induced significant upregulation of the PLAU gene and elevated urokinase activity was confirmed through zymography and activity assay. Overall, these results indicate that pulsatile shear stress promotes breast cancer cell proliferation, invasive potential, chemoresistance, and PLAU signaling.

The Role of Tumor Microenvironment in Chemoresistance: 3D Extracellular Matrices as Accomplices

BACKGROUND

The functional interplay between tumor cells and their adjacent stroma has been suggested to play crucial roles in the initiation and progression of tumors and the effectiveness of chemotherapy. The extracellular matrix (ECM), a complex network of extracellular proteins, provides both physical and chemicals cues necessary for cell proliferation, survival, and migration. Understanding how ECM composition and biomechanical properties affect cancer progression and response to chemotherapeutic drugs is vital to the development of targeted treatments.

METHODS

3D cell-derived-ECMs and esophageal cancer cell lines were used as a model to investigate the effect of ECM proteins on esophageal cancer cell lines response to chemotherapeutics. Immunohistochemical and qRT-PCR evaluation of ECM proteins and integrin gene expression was done on clinical esophageal squamous cell carcinoma biopsies. Esophageal cancer cell lines (WHCO1, WHCO5, WHCO6, KYSE180, KYSE 450 and KYSE 520) were cultured on decellularised ECMs (fibroblasts-derived ECM; cancer cell-derived ECM; combinatorial-ECM) and treated with 0.1% Dimethyl sulfoxide (DMSO), 4.2 µM cisplatin, 3.5 µM 5-fluorouracil and 2.5 µM epirubicin for 24 h. Cell proliferation, cell cycle progression, colony formation, apoptosis, migration and activation of signaling pathways were used as our study endpoints.

RESULTS

The expression of collagens, fibronectin and laminins was significantly increased in esophageal squamous cell carcinomas (ESCC) tumor samples compared to the corresponding normal tissue. Decellularised ECMs abrogated the effect of drugs on cancer cell cycling, proliferation and reduced drug induced apoptosis by 20⁻60% that of those plated on plastic. The mitogen-activated protein kinase-extracellular signal-regulated kinase (MEK-ERK) and phosphoinositide 3-kinase-protein kinase B (PI3K/Akt) signaling pathways were upregulated in the presence of the ECMs. Furthermore, our data show that concomitant addition of chemotherapeutic drugs and the use of collagen- and fibronectin-deficient ECMs through siRNA inhibition synergistically increased cancer cell sensitivity to drugs by 30⁻50%, and reduced colony formation and cancer cell migration.

CONCLUSION

Our study shows that ECM proteins play a key role in the response of cancer cells to chemotherapy and suggest that targeting ECM proteins can be an effective therapeutic strategy against chemoresistant tumors.

Engineering Bioinspired Antioxidant Materials Promoting Cardiomyocyte Functionality and Maturation for Tissue Engineering Application

Oxidative stress plays an important role in various pathological conditions, such as wound healing, inflammation, myocardial infarction, and biocompatibility of the materials. Antioxidant polymers to attenuate oxidative stress is an emerging field of biomaterial research with a huge impact in the field of tissue engineering and regenerative medicine. We describe here the fabrication and evaluation of an elastomeric antioxidant polyurethane (PUAO) for tissue engineering applications. Uniaxial and cyclic tensile testing, thermal analysis, degradation, cytotoxicity and antioxidant analysis was carried out. An in vitro oxidative stress model demonstrated that PUAO reduced intracellular oxidative stress in H9C2 cardiomyocytes (p < 0.05) and attenuated reactive oxygen species (ROS) induced cell death (p < 0.001). Under simulated ischemic reperfusion, PUAO could rescue hypoxia induced cell death. Further as a proof of concept, neonatal rat cardiomyocytes cultured on PUAO film displayed synchronous beating with mature phenotype showing expression of cardiac specific α-actinin, troponin-T, and connexin-43 proteins. Intracellular calcium transients established the functionality of cultured cardiomyocytes on PUAO film. Our study demonstrated the potential of this biomaterial to be developed into tissue engineered scaffold to attenuate oxidative stress for treatment of diseased conditions with increased oxidative stress, such as cardiovascular diseases, chronic wound healing, and myocardial infarction.

Thermoresponsive double network cryogels from dendronized copolymers showing tunable encapsulation and release of proteins

Thermoresponsive double network cryogels were prepared from OEG-based dendronized copolymers with PVA, which can reversibly capture and release proteins.

Elasticity-based development of functionally enhanced multicellular 3D liver encapsulated in hybrid hydrogel

Current in vitro liver models provide three-dimensional (3-D) microenvironments in combination with tissue engineering technology and can perform more accurate in vivo mimicry than two-dimensional models. However, a human cell-based, functionally mature liver model is still desired, which would provide an alternative to animal experiments and resolve low-prediction issues on species differences. Here, we prepared hybrid hydrogels of varying elasticity and compared them with a normal liver, to develop a more mature liver model that preserves liver properties in vitro. We encapsulated HepaRG cells, either alone or with supporting cells, in a biodegradable hybrid hydrogel. The elastic modulus of the 3D liver dynamically changed during culture due to the combined effects of prolonged degradation of hydrogel and extracellular matrix formation provided by the supporting cells. As a result, when the elastic modulus of the 3D liver model converges close to that of the in vivo liver (≅ 2.3 to 5.9 kPa), both phenotypic and functional maturation of the 3D liver were realized, while hepatic gene expression, albumin secretion, cytochrome p450-3A4 activity, and drug metabolism were enhanced. Finally, the 3D liver model was expanded to applications with embryonic stem cell-derived hepatocytes and primary human hepatocytes, and it supported prolonged hepatocyte survival and functionality in long-term culture. Our model represents critical progress in developing a biomimetic liver system to simulate liver tissue remodeling, and provides a versatile platform in drug development and disease modeling, ranging from physiology to pathology.

STATEMENT OF SIGNIFICANCE

We provide a functionally improved 3D liver model that recapitulates in vivo liver stiffness. We have experimentally addressed the issues of orchestrated effects of mechanical compliance, controlled matrix formation by stromal cells in conjunction with hepatic differentiation, and functional maturation of hepatocytes in a dynamic 3D microenvironment. Our model represents critical progress in developing a biomimetic liver system to simulate liver tissue remodeling, and provides a versatile platform in drug development and disease modeling, ranging from physiology to pathology. Additionally, recent advances in the stem-cell technologies have made the development of 3D organoid possible, and thus, our study also provides further contribution to the development of physiologically relevant stem-cell-based 3D tissues that provide an elasticity-based predefined biomimetic 3D microenvironment.

Enhanced Hepatic Functions of Genetically Modified Mouse Hepatoma Cells by Spheroid Culture for Drug Toxicity Screening

While hepatic cell lines are mainly used for in vitro drug induced toxicity studies, they exhibit limited functionalities. To overcome this, the authors have employed genetically engineered mouse hepatoma cells, Hepa/8F5, wherein expression of liver enriched transcription factors is induced by doxycycline leading to increased functionality. Further enhancement in functionality is achieved by spheroid culture in a previously developed 3D cell culture platform. Cells are seeded in presence of temperature-responsive poly(N-isopropylacrylamide) on poly(N-isopropylacrylamide--co-gelatin) cryogel scaffold based high throughput platform. Cells seeded in presence of poly(N-isopropylacrylamide) and induced with doxycycline exhibited highest functionalities. There is an increase of ≈26, 36, and 39% in albumin secretion, ammonia removal, and CYP3A4 activity, respectively. Morphological analysis showed arrest in cell proliferation and enlarged nucleus in presence of doxycyline and spheroid formation in presence of poly(N-isopropylacrylamide). Drug induced liver toxicity studies revealed that cells induced with doxycycline are resistive to tamoxifen but sensitive to acetaminophen whereas, cultures initiated in presence of poly(N-isopropylacrylamide) are resistive to both the drugs which is indicative of diffusional barrier of the spheroids. The authors conclude that Hepa/8F5 cells show enhanced functionality in cryogel based spheroid culture platform which can be successfully used for high throughput screening of hepatic toxicity in vitro.

Development of polymer based cryogel matrix for transportation and storage of mammalian cells

We studied the potential of polymeric cryogel matrices such as 2-hydroxyethyl methacrylate (HEMA)-agarose (HA) and gelatin matrix as a transporting and storage material for mammalian cells. Both the HA and gelatin matrices were found to possess a homogenous distribution of pores as shown by scanning electron microscopic (SEM) images and flow rate of 8 and 5 mL/min, respectively. In the case of HA cryogel, after 5 days of simulated transportation, C2C12 cells kept in cryogel matrix showed higher percentage viability (89%) as compared to 64.5% viability of cells kept in suspension culture. The cells recovered from the HA cryogel were able to proliferate as revealed by the microscopic analysis. In the case of gelatin cryogel, it was shown that C2C12 cells seeded on the cryogel under simulated transportation condition were found to proliferate over the period of 5 days. It was also observed that the cells after simulation can be cryopreserved and the duration of cryopreservation does not affect their viability. Furthermore, gelatin cryogel was used for cryopreservation of HepG2 and HUVEC cells to extend the system for other cell types. These results show the potential of cryogels as efficient, low-cost transporting matrix at room temperature and in cryo-conditions.

Pamidronic acid-grafted nHA/PLGA hybrid nanofiber scaffolds suppress osteoclastic cell viability and enhance osteoblastic cell activity

Controlling osteoclast activity helps in prevention of bone resorption.