Fabrication of PNIPAm-based thermoresponsive hydrogel microwell arrays for tumor spheroid formation

A Thermo-responsive collapse system for controlling heterogeneous cell localization, ratio and interaction for three-dimensional solid tumor modeling

Cancer immunotherapy using engineered cytotoxic effector cells has demonstrated significant potential. The limited spatial complexity of existing in vitro models, however, poses a challenge to mechanistic studies attempting to approve existing approaches of effector cell-mediated cytotoxicity within a three-dimensional, solid tumor-like environment. To gain additional experimental control, we developed an approach for constructing three-dimensional (3D) culture models using smart polymers that form temperature responsive hydrogels. By embedding cells in these hydrogels, we constructed 3D models to organize multiple cell populations at specified ratios on-demand and gently position them by exploiting the hydrogel phase transition. These systems were amenable to imaging at low- and high-resolution to evaluate cell-to-cell interactions, as well as to dissociation to allow for single cell analyses. We have called this approach "thermal collapse of strata" (TheCOS) and demonstrated its use in creating complex cell assemblies on demand in both layers and spheroids. As an application, we utilized TheCOS to evaluate the impact of directionality of degranulation of natural killer (NK) cell lytic granules. Blocking lytic granule convergence and polarization by inhibiting dynein has been shown to induce bystander killing in single cell suspensions. Using TheCOS we showed that lytic granule dispersion induced by dynein inhibition can be sustained in 3D and results in a multi-directional killing including that of non-triggering bystander cells. By imaging TheCOS experiments, we were able to map a "kill zone" associated with multi-directional degranulation in simulated solid tumor environments. TheCOS should allow for the testing of approaches to alter the mechanics of cytotoxicity as well as to generate a wide-array of human tumor microenvironments to assist in the acceleration of tumor immunotherapy.

Fabrication of Microstructured Hydrogels via Dehydration for On-Demand Applications

Microstructured hydrogels show promising applications in various engineering fields from micromolds to anisotropic wetting surfaces and microfluidics. Although methods like molding by, e.g., casting as well as 3D printing are developed to fabricate microstructured hydrogels, developing fabrication methods with high controllability and low-cost is an on-going challenge. Here, a method is presented for creating microstructures through the dehydration of double network hydrogels. This method utilizes common acrylate monomers and a mask-assisted photopolymerization process, requiring no complex equipment or laborious chemical synthesis process. The shape and profile of microstructures can be easily controlled by varying the exposure time and the mask used during photopolymerization. By altering the monomer and the mask used for fabricating the second network hydrogel, both convex and concave microstructures can be produced. To showcase the utility of this method, the patterned hydrogel is utilized as a mold to fabricate a polydimethylsiloxane microlens array via soft lithography for imaging application. In addition, a patterned hydrogel surface exhibiting obvious anisotropic wetting properties and open microfluidic devices which can achieve fast directional superspreading within milliseconds are also fabricated to demonstrate the versatility of the method for different engineering fields.

Synthetic and natural polymer hydrogels: A review of 3D spheroids and drug delivery

This review centers on the synthesis and characterization of both natural and synthetic hydrogels, highlighting their diverse applications across various fields. We will delve into the evolution of hydrogels, focusing on the importance of polysaccharide-based and synthetic variants, which have been particularly chosen for 3D spheroid development in cancer research and drug delivery. A detailed background on the research and specific methodologies, including the in-situ free radical polymerization used for synthesizing these hydrogels, will be extensively discussed. Additionally, the review will explore various applications of these hydrogels, such as their self-healing properties, swelling ratios, pH responsiveness, and cell viability. A comprehensive literature review will support this investigation. Ultimately, this review aims to clearly outline the objectives and significance of hydrogel synthesis and their applications.

Development and characterization of a novel poly(N-isopropylacrylamide)-based thermoresponsive photoink and its applications in DLP bioprinting

The field of 3-dimensional (3D) bioprinting has significantly expanded capabilities in producing precision-engineered hydrogel constructs, and recent years have seen the development of various stimuli-responsive bio- and photoinks. There is, however, a distinct lack of digital light processing (DLP)-compatible photoinks with thermoresponsivity. To remedy this, this work focuses on formulating and optimizing a versatile ink for DLP printing of thermoresponsive hydrogels, with numerous potential applications in tissue engineering, drug delivery, and adjacent biomedical fields. Photoink optimization was carried out using a multifactorial study design. The optimized photoink yielded crosslinked hydrogels with strong variations in hydrophobicity (contact angles of 44.4° LCST), indicating marked thermoresponsivity. Mechanical- and rheological characterization of the printed hydrogels showed significant changes above the LCST: storage- and loss moduli both increased and loss tangent and compressive modulus decreased above this temperature (P ≤ 0.01). The highly cytocompatible hydrogel microwell arrays yielded both single- and multilayer spheroids with human dermal fibroblasts (HDFs) and HeLa cells successfully. Evaluation of the release of encapsulated model macro- (bovine serum albumin, BSA) and small molecule (rhodamine B) drugs in a buffer solution showed an interestingly inverted thermoresponsive release profile with >80% release at room temperature and about 50-60% release above the gels' LCST. All told, the optimized ink holds great promise for multiple biomedical applications including precise and high-resolution fabrication of complex tissue structures, development of smart drug delivery systems and 3D cell culture.

Imaging-Based Efficacy Evaluation of Cancer Immunotherapy in Engineered Tumor Platforms and Tumor Organoids

Cancer immunotherapy is used to treat tumors by modulating the immune system. Although the anticancer efficacy of cancer immunotherapy has been evaluated prior to clinical trials, conventional in vivo animal and endpoint models inadequately replicate the intricate process of tumor elimination and reflect human-specific immune systems. Therefore, more sophisticated models that mimic the complex tumor-immune microenvironment must be employed to assess the effectiveness of immunotherapy. Additionally, using real-time imaging technology, a step-by-step evaluation can be applied, allowing for a more precise assessment of treatment efficacy. Here, an overview of the various imaging-based evaluation platforms recently developed for cancer immunotherapeutic applications is presented. Specifically, a fundamental technique is discussed for stably observing immune cell-based tumor cell killing using direct imaging, a microwell that reproduces a confined space for spatial observation, a droplet assay that facilitates cell-cell interactions, and a 3D microphysiological system that reconstructs the vascular environment. Furthermore, it is suggested that future evaluation platforms pursue more human-like immune systems.

Knockout cancer by nano-delivered immunotherapy using perfusion-aided scaffold-based tumor-on-a-chip

Cancer is a multifactorial disease produced by mutations in the oncogenes and tumor suppressor genes, which result in uncontrolled cell proliferation and resistance to cell death. Cancer progresses due to the escape of altered cells from immune monitoring, which is facilitated by the tumor's mutual interaction with its microenvironment. Understanding the mechanisms involved in immune surveillance evasion and the significance of the tumor microenvironment might thus aid in developing improved therapies. Although in vivo models are commonly utilized, they could be better for time, cost, and ethical concerns. As a result, it is critical to replicate an in vivo model and recreate the cellular and tissue-level functionalities. A 3D cell culture, which gives a 3D architecture similar to that found in vivo, is an appropriate model. Furthermore, numerous cell types can be cocultured, establishing cellular interactions between TME and tumor cells. Moreover, microfluidics perfusion can provide precision flow rates, thus simulating tissue/organ function. Immunotherapy can be used with the perfused 3D cell culture technique to help develop successful therapeutics. Immunotherapy employing nano delivery can target the spot and silence the responsible genes, ensuring treatment effectiveness while minimizing adverse effects. This study focuses on the importance of 3D cell culture in understanding the pathophysiology of 3D tumors and TME, the function of TME in drug resistance, tumor progression, and the development of advanced anticancer therapies for high-throughput drug screening.

Utility of 1.5 Tesla MRI Scanner in the Management of Small Sample Sizes Driven from 3D Breast Cell Culture

The aim of this work was to use and optimize a 1.5 Tesla magnetic resonance imaging (MRI) system for three-dimensional (3D) images of small samples obtained from breast cell cultures in vitro. The basis of this study was to design MRI equipment to enable imaging of MCF-7 breast cancer cell cultures (about 1 million cells) in 1.5 and 2 mL glass tubes and/or bioreactors with an external diameter of less than 20 mm. Additionally, the development of software to calculate longitudinal and transverse relaxation times is described. Imaging tests were performed using a clinical MRI scanner OPTIMA 360 manufactured by GEMS. Due to the size of the tested objects, it was necessary to design additional receiving circuits allowing for the study of MCF-7 cell cultures placed in glass bioreactors. The examined sample's volume did not exceed 2.0 mL nor did the number of cells exceed 1 million. This work also included a modification of the sequence to allow for the analysis of T1 and T2 relaxation times. The analysis was performed using the MATLAB package (produced by MathWorks). The created application is based on medical MR images saved in the DICOM3.0 standard which ensures that the data analyzed are reliable and unchangeable in an unintentional manner that could affect the measurement results. The possibility of using 1.5 T MRI systems for cell culture research providing quantitative information from in vitro studies was realized. The scanning resolution for FOV = 5 cm and the matrix was achieved at a level of resolution of less than 0.1 mm/pixel. Receiving elements were built allowing for the acquisition of data for MRI image reconstruction confirmed by images of a phantom with a known structure and geometry. Magnetic resonance sequences were modified for the saturation recovery (SR) method, the purpose of which was to determine relaxation times. An application in MATLAB was developed that allows for the analysis of T1 and T2 relaxation times. The relaxation times of cell cultures were determined over a 6-week period. In the first week, the T1 time value was 1100 ± 40 ms, which decreased to 673 ± 59 ms by the sixth week. For T2, the results were 171 ± 10 ms and 128 ± 12 ms, respectively.

Wound Microenvironment Self-Adjusting Hydrogels with Thermo-Sensitivity for Promoting Diabetic Wound Healing

The hard-healing chronic wounds of diabetics are still one of the most intractable problems in clinical skin injury repair. Wound microenvironments directly affect wound healing speed, but conventional dressings exhibit limited efficacy in regulating the wound microenvironment and facilitating healing. To address this serious issue, we designed a thermo-sensitive drug-controlled hydrogel with wound self-adjusting effects, consisting of a sodium alginate (SA), Antheraeapernyi silk gland protein (ASGP) and poly(N-isopropylacrylamide) (PNIPAM) for a self-adjusting microenvironment, resulting in an intelligent releasing drug which promotes skin regeneration. PNIPAM has a benign temperature-sensitive effect. The contraction, drugs and water molecules expulsion of hydrogel were generated upon surpassing lower critical solution temperatures, which made the hydrogel system have smart drug release properties. The addition of ASGP further improves the biocompatibility and endows the thermo-sensitive drug-controlled hydrogel with adhesion. Additionally, in vitro assays demonstrate that the thermo-sensitive drug-controlled hydrogels have good biocompatibility, including the ability to promote the adhesion and proliferation of human skin fibroblast cells. This work proposes an approach for smart drug-controlled hydrogels with a thermo response to promote wound healing by self-adjusting the wound microenvironment.

The interplay of cells, polymers, and vascularization in three-dimensional lung models and their applications in COVID-19 research and therapy

Millions of people have been affected ever since the emergence of the corona virus disease of 2019 (COVID-19) outbreak, leading to an urgent need for antiviral drug and vaccine development. Current experimentation on traditional two-dimensional culture (2D) fails to accurately mimic the in vivo microenvironment for the disease, while in vivo animal model testing does not faithfully replicate human COVID-19 infection. Human-based three-dimensional (3D) cell culture models such as spheroids, organoids, and organ-on-a-chip present a promising solution to these challenges. In this report, we review the recent 3D in vitro lung models used in COVID-19 infection and drug screening studies and highlight the most common types of natural and synthetic polymers used to generate 3D lung models.

Smart Triboelectric Nanogenerators Based on Stimulus-Response Materials: From Intelligent Applications to Self-Powered Systems

Smart responsive materials can react to external stimuli via a reversible mechanism and can be directly combined with a triboelectric nanogenerator (TENG) to deliver various intelligent applications, such as sensors, actuators, robots, artificial muscles, and controlled drug delivery. Not only that, mechanical energy in the reversible response of innovative materials can be scavenged and transformed into decipherable electrical signals. Because of the high dependence of amplitude and frequency on environmental stimuli, self-powered intelligent systems may be thus built and present an immediate response to stress, electrical current, temperature, magnetic field, or even chemical compounds. This review summarizes the recent research progress of smart TENGs based on stimulus-response materials. After briefly introducing the working principle of TENG, we discuss the implementation of smart materials in TENGs with a classification of several sub-groups: shape-memory alloy, piezoelectric materials, magneto-rheological, and electro-rheological materials. While we focus on their design strategy and function collaboration, applications in robots, clinical treatment, and sensors are described in detail to show the versatility and promising future of smart TNEGs. In the end, challenges and outlooks in this field are highlighted, with an aim to promote the integration of varied advanced intelligent technologies into compact, diverse functional packages in a self-powered mode.

The Use of Biomaterials in Three-Dimensional Culturing of Cancer Cells

Cell culture is an important tool in biological research. Most studies use 2D cell culture, but cells grown in 2D cell culture have drawbacks, including limited cell and cell-extracellular matrix interactions, which make it inaccurate to model conditions in vivo. Anticancer drug screening is an important research and development process for developing new drugs. As an experiment to mimic the cancer environment in vivo, several studies have been carried out on 3-dimensional (3D) cell cultures with added biomaterials. The use of hydrogel in 3D culture cells is currently developing. The type of hydrogel used might influence cell morphology, viability, and drug screening outcome. Therefore, this review discusses 3D cell culture research regarding the addition of biomaterials.

Systems and in vitro pharmacology profiling of diosgenin against breast cancer

Aim: The purpose of this study was to establish a mode of action for diosgenin against breast cancer employing a range of system biology tools and to corroborate its results with experimental facts. Methodology: The diosgenin-regulated domains implicated in breast cancer were enriched in the Kyoto Encyclopedia of Genes and Genomes database to establish diosgenin-protein(s)-pathway(s) associations. Later, molecular docking and the lead complexes were considered for molecular dynamics simulations, MMPBSA, principal component, and dynamics cross-correlation matrix analysis using GROMACS v2021. Furthermore, survival analysis was carried out for the diosgenin-regulated proteins that were anticipated to be involved in breast cancer. For gene expression analyses, the top three targets with the highest binding affinity for diosgenin and tumor expression were examined. Furthermore, the effect of diosgenin on cell proliferation, cytotoxicity, and the partial Warburg effect was tested to validate the computational findings using functional outputs of the lead targets. Results: The protein-protein interaction had 57 edges, an average node degree of 5.43, and a p-value of 3.83e-14. Furthermore, enrichment analysis showed 36 KEGG pathways, 12 cellular components, 27 molecular functions, and 307 biological processes. In network analysis, three hub proteins were notably modulated: IGF1R, MDM2, and SRC, diosgenin with the highest binding affinity with IGF1R (binding energy -8.6 kcal/mol). Furthermore, during the 150 ns molecular dynamics (MD) projection run, diosgenin exhibited robust intermolecular interactions and had the least free binding energy with IGF1R (-35.143 kcal/mol) compared to MDM2 (-34.619 kcal/mol), and SRC (-17.944 kcal/mol). Diosgenin exhibited the highest cytotoxicity against MCF7 cell lines (IC₅₀ 12.05 ± 1.33) µg/ml. Furthermore, in H₂O₂-induced oxidative stress, the inhibitory constant (IC₅₀ 7.68 ± 0.51) µg/ml of diosgenin was lowest in MCF7 cell lines. However, the reversal of the Warburg effect by diosgenin seemed to be maximum in non-cancer Vero cell lines (EC₅₀ 15.27 ± 0.95) µg/ml compared to the rest. Furthermore, diosgenin inhibited cell proliferation in SKBR3 cell lines more though. Conclusion: The current study demonstrated that diosgenin impacts a series of signaling pathways, involved in the advancement of breast cancer, including FoxO, PI3K-Akt, p53, Ras, and MAPK signaling. Additionally, diosgenin established a persistent diosgenin-protein complex and had a significant binding affinity towards IGF1R, MDM2, and SRC. It is possible that this slowed down cell growth, countered the Warburg phenomenon, and showed the cytotoxicity towards breast cancer cells.

Biodegradable and Inherently Fluorescent pH-Responsive Nanoparticles for Cancer Drug Delivery

PURPOSE

The development of two novel pH-only and pH- and thermo-responsive theranostic nanoparticle (NP) formulations to deliver an anticancer drug and track the accumulation and therapeutic efficacy of the formulations through inherent fluorescence.

METHODS

A pH-responsive formulation was synthesized from biodegradable photoluminescent polymer (BPLP) and sodium bicarbonate (SBC) via an emulsion technique, while a thermoresponsive BPLP copolymer (TFP) and SBC were used to synthesize a dual-stimuli responsive formulation via free radical co-polymerization. Cisplatin was employed as a model drug and encapsulated during synthesis. Size, surface charge, morphology, pH-dependent fluorescence, lower critical solution temperature (LCST; TFP NPs only), cytocompatibility and in vitro uptake, drug release kinetics and anticancer efficacy were assessed.

RESULTS

While all BPLP-SBC and TFP-SBC combinations produced spherical nanoparticles of a size between 200-300 nm, optimal polymer-SBC ratios were selected for further study. Of these, the optimal BPLP-SBC formulation was found to be cytocompatible against primary Type-1 alveolar epithelial cells (AT1) up to 100 μg/mL, and demonstrated sustained drug release over 14 days, dose-dependent uptake, and marked pH-dependent A549 cancer cell killing (72 vs. 24% cell viability, at pH 7.4 vs. 6.0). The optimal TFP-SBC formulation showed excellent cytocompatibility against AT1 cells up to 500 μg/mL, sustained release characteristics, dose-dependent uptake, pH-dependent (78% at pH 7.4 vs. 64% at pH 6.0 at 37°C) and marked temperature-dependent A549 cancer cell killing (64% at 37°C vs. 37% viability at pH 6.0, 41°C).

CONCLUSIONS

In all, both formulations hold promise as inherently fluorescent, stimuli-responsive theranostic platforms for passively targeted anti-cancer therapy.

Validation and scalability of homemade polycaprolactone macrobeads grafted with thermo-responsive poly(N-isopropylacrylamide) for mesenchymal stem cell expansion and harvesting

In this study, polycaprolactone (PCL) macrobeads were prepared by an oil-in-water (o/w) emulsion solvent evaporation method with poly(vinyl alcohol) (PVA) as an emulsifier and conjugated to poly(N-isopropylacrylamide) (PNIPAAm) to be used as cell carriers with noninvasive cell detachment properties (thermo-response). Following previous studies with PCL-PNIPAAm carriers, our objectives were to confirm the successful conjugation on homemade macrobeads and to show the advantages of homemade production over commercial beads to control morphological, biological, and fluidization properties. The effects of PCL concentration on the droplet formation and of flow rate and PVA concentration on the size of the beads were demonstrated. The size of the beads, all spherical, ranged from 0.5 to 3.7 mm with four bead categories based on production parameters. The morphology and size of the beads were observed by scanning electron microscopy to show surface roughness enhancing cell attachment and proliferation compared to commercial beads. The functionalization steps with PNIPAAm were then characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersion spectroscopy. PNIPAAm-grafted macrobeads allowed mesenchymal stem cells (MSCs) to spread and grow for up to 21 days. By reducing the temperature to 25°C, the MSCs were successfully detached from the PCL-PNIPAAm beads as observed with fluorescence microscopy. Furthermore, we validated the scalability potential of both macrobeads production and conjugation with PCL, to produce easily kilograms of thermo-responsive macrocarriers in a lab environment. This could help moving such approaches towards clinically and industrially relevant processes were cell expansion is needed at very large scale.

A New Reversible Thermosensitive Liquid-Solid TENG Based on a P(NIPAM-MMA) Copolymer for Triboelectricity Regulation and Temperature Monitoring

Intelligent and highly precise control of liquid-solid triboelectricity is of great significance for energy collection and electrostatic prevention. However, most of the traditional methods are irreversible and complex, greatly limiting their applicability. Here, a reversible thermosensitive liquid-solid triboelectric nanogenerator (L-S TENG) is assembled based on P(NIPAM-MMA) (PNM) copolymer for tunable triboelectrification. Through temperature regulation, the conformation between acylamino and isopropyl groups changes with the interfacial wettability and triboelectricity of PNM. When the temperature rises from 20 to 60 °C, the contact angle of PNM rises from 22.49° to 82.08°, and the output of the PNM-based L-S TENG shows a 27-fold increase. In addition, this transformation is reversible and repeatable with excellent durability for up to 60 days. Other organic liquids, such as glycol, exhibit positive response to temperature for this PNM-based L-S TENG. Polymers including polymethylmethacrylic, polytetrafluoroethylene, and polyimide are verified to not have such thermo-sensitivity properties. In addition, a droplet-based wireless warning system based on PNM is designed and actuated for monitoring specific temperature. The introduction of thermal PNM not only provides new material for reversible manipulation of L-S TENG, but also provides a new method for designing highly sensitive temperature warning sensors.

Clinical Application Perspectives of Lung Cancers 3D Tumor Microenvironment Models for In Vitro Cultures

Despite the enormous progress and development of modern therapies, lung cancer remains one of the most common causes of death among men and women. The key element in the development of new anti-cancer drugs is proper planning of the preclinical research phase. The most adequate basic research exemplary for cancer study are 3D tumor microenvironment in vitro models, which allow us to avoid the use of animal models and ensure replicable culture condition. However, the question tormenting the scientist is how to choose the best tool for tumor microenvironment research, especially for extremely heterogenous lung cancer cases. In the presented review we are focused to explain the key factors of lung cancer biology, its microenvironment, and clinical gaps related to different therapies. The review summarized the most important strategies for in vitro culture models mimicking the tumor–tumor microenvironmental interaction, as well as all advantages and disadvantages were depicted. This knowledge could facilitate the right decision to designate proper pre-clinical in vitro study, based on available analytical tools and technical capabilities, to obtain more reliable and personalized results for faster introduction them into the future clinical trials.

New Born Calf Serum Can Induce Spheroid Formation in Breast Cancer KAIMRC1 Cell Line

Three-dimensional (3D) cell culture systems have become very popular in the field of drug screening and discovery. There is an immense demand for highly efficient and easy methods to produce 3D spheroids in any cell format. We have developed a novel and easy method to produce spheroids from the newly isolated KAIMRC1 cell line in vitro. It can be used as a 3D model to study proliferation, differentiation, cell death, and drug response of cancer cells. Our procedure requires growth media supplemented with 10% new born calf serum (NBCS) and regular cell culture plates to generate KAIMRC1 spheroids without the need for any specialized 3D cell culture system. This procedure generates multiple spheroids within a 12–24-h culture. KAIMRC1 spheroids are compact, homogeneous in size and morphology with a mean size of 55.8 µm (±3.5). High content imaging (HCI) of KAIMRC1 spheroids treated with a panel of 240 compounds resulted in the identification of several highly specific compounds towards spheroids. Immunophenotyping of KAIMRC1 spheroids revealed phosphorylation of FAK, cJUN, and E-cadherin, which suggests the involvement of JNK/JUN pathway in the KAIMRC1 spheroids formation. Gene expression analysis showed upregulation of cell junction genes, GJB3, DSC1, CLDN5, CLDN8, and PLAU. Furthermore, co-culture of KAIMRC1 cells with primary cancer-associated-fibroblasts (CAFs) showcased the potential of these cells in drug discovery application.

Recent Advances in Multicellular Tumor Spheroid Generation for Drug Screening

Multicellular tumor spheroids (MCTs) have been employed in biomedical fields owing to their advantage in designing a three-dimensional (3D) solid tumor model. For controlling multicellular cancer spheroids, mimicking the tumor extracellular matrix (ECM) microenvironment is important to understand cell-cell and cell-matrix interactions. In drug cytotoxicity assessments, MCTs provide better mimicry of conventional solid tumors that can precisely represent anticancer drug candidates' effects. To generate incubate multicellular spheroids, researchers have developed several 3D multicellular spheroid culture technologies to establish a research background and a platform using tumor modelingvia advanced materials science, and biosensing techniques for drug-screening. In application, drug screening was performed in both invasive and non-invasive manners, according to their impact on the spheroids. Here, we review the trend of 3D spheroid culture technology and culture platforms, and their combination with various biosensing techniques for drug screening in the biomedical field.