Three-dimensional cell culture systems and their applications in drug discovery and cell-based biosensors

Generation, interrogation, and future applications of microglia-containing brain organoids

Brain organoids encompass a large collection of in vitro stem cell-derived 3D culture systems that aim to recapitulate multiple aspects of in vivo brain development and function. First, this review provides a brief introduction to the current state-of-the-art for neuro-ectoderm brain organoid development, emphasizing their biggest advantages in comparison with classical two-dimensional cell cultures and animal models. However, despite their usefulness for developmental studies, a major limitation for most brain organoid models is the absence of contributing cell types from endodermal and mesodermal origin. As such, current research is highly investing towards the incorporation of a functional vasculature and the microglial immune component. In this review, we will specifically focus on the development of immune-competent brain organoids. By summarizing the different approaches applied to incorporate microglia, it is highlighted that immune-competent brain organoids are not only important for studying neuronal network formation, but also offer a clear future as a new tool to study inflammatory responses in vitro in 3D in a brain-like environment. Therefore, our main focus here is to provide a comprehensive overview of assays to measure microglial phenotype and function within brain organoids, with an outlook on how these findings could better understand neuronal network development or restoration, as well as the influence of physical stress on microglia-containing brain organoids. Finally, we would like to stress that even though the development of immune-competent brain organoids has largely evolved over the past decade, their full potential as a pre-clinical tool to study novel therapeutic approaches to halt or reduce inflammation-mediated neurodegeneration still needs to be explored and validated.

A novel tubulin inhibitor, No.07, shows anti-cancer and anti-metastatic effects in colon cancer and tumoroids

Colorectal cancer is a highly metastatic disease and the second leading cause of cancer-related death worldwide. Despite the use of various treatment strategies, including chemotherapy and targeted therapy, challenges such as toxicity, drug resistance, and poor response indicate the critical need for new therapeutic agents. Microtubule target agents are one of the major treatment options for chemotherapy in various cancer patients. However, most of these agents are substrates of the MDR1 protein, which leads to the development of multidrug resistance, significantly limiting their effectiveness. Therefore, the development of new drugs is being actively pursued. In this study, we synthesized a novel compound, No.07, which demonstrates significant anti-cancer activity in 3D spheroid models, patient-derived colon cancer organoid models, and mice xenograft models. No.07 directly binds to tubulin dimers, interfering with microtubule polymerization and thereby disrupting tubulin dynamics, ultimately inducing mitotic arrest. Furthermore, No.07 increases mitochondria reactive oxygen species level, leading to the inactivation of the RAF-MEK-ERK signaling cascade, which consequently inhibits metastasis. Notably, Swiss ADME predictions suggest that No.07 is not a substrate of MDR1 and can cross the blood-brain barrier, unlike other microtubule target agents that are limited by MDR1-mediated drug resistance and poor brain penetration. Additionally, experiments using multidrug-resistant cell lines confirmed that No.07 effectively overcomes multidrug resistance, providing a significant improvement over traditionally used chemotherapy agents. In conclusion, No.07 has the potential to address the limitations of existing treatments as a novel therapeutic option.

Avian-Specific Evidence for an Estrogen Receptor Agonism Adverse Outcome Pathway Based on Chicken Embryos and LMH 3D Spheroids Exposed to Ethinylestradiol and Bisphenol A

Several adverse outcome pathways (AOPs) describe the effects of endocrine disrupting compounds on estrogen signaling. Substantial data support an AOP related to estrogen receptor (ER) antagonism, leading to decreased fecundity in fish. In this study, data were generated for an ER agonism AOP leading to reduced fecundity in avian species (AOP537). Chicken embryos and the chicken leghorn male hepatoma cell line, LMH, were used to elucidate key events associated with estrogen signaling following exposure to 17α-ethinylestradiol (EE2) and bisphenol A (BPA). Embryos were exposed via egg injection. Viability and hepatic estrogen-responsive gene expression data were collected at midincubation (embryonic day [ED] 11). Changes in plasma vitellogenin (VTG), gonad morphology and growth were evaluated prior to pipping (ED20). Both chemicals dysregulated estrogen-responsive genes in hepatic tissue and increased plasma VTG concentrations. In LMH spheroids, EE2 and BPA altered estrogen-responsive genes and VTG concentrations at 24 and 48 h, respectively. Gonadal histology revealed oocyte-type cells and loss of testicular cords in male embryos exposed to EE2 and BPA. Overall, EE2 and BPA upregulated VTG mRNA expression, increased plasma VTG, and caused impairments in gonadal development. These results contribute avian-specific evidence to support an endocrine disruption AOP describing the relationship between disrupted VTG synthesis and impaired reproduction.

Cryopreservation of human lung adenocarcinoma spheroids using MMC based cryomixtures

Cryopreservation remains crucial bottleneck for storing and transporting bioengineered 3D cell models, vital for preclinical drug development and cancer research. Conventional cryoprotectants like fetal bovine serum (FBS) and dimethyl sulfoxide (DMSO) present cytotoxicity challenges and lack efficacy in maintaining structural integrity and viability in complex 3D culture models. This study investigates the efficacy of two carbohydrate-based macromolecular crowders (MMCs), polydextrose III (PD) and resistant maltodextrin (rMD), in cryopreserving human lung adenocarcinoma spheroids as alternatives to FBS. Spheroids were cryopreserved at -80 and -196 °C using MMC-based cryomixtures, with subsequent evaluation of cell viability, structural integrity, and proliferation markers post-thaw. Results indicate that MMC-based cryomixtures, particularly PD, provide superior cryoprotection, preserving the structural and functional integrity of A549 spheroids over a 60-day storage period at -196 °C. Immunocytochemistry of vimentin and Ki67 biomarkers demonstrated that PD-cryopreserved spheroids exhibited consistent structural stability and retained proliferative capacity, contrasting with those stored in conventional FBS-based cryomixtures, which showed marked deterioration in cellular morphology and viability. Apoptosis profiling revealed a lower incidence of cell death in MMC-preserved spheroids, with live cell percentages stabilizing around 50% at -80 °C and approximately 54% at -196 °C over the extended storage period. Further characterization revealed protection of the necrotic core and cellular junctions PD-cryopreserved spheroids. These findings suggest that MMC-based cryomixtures, especially PD, are effective alternatives for cryopreservation of tumor spheroids. The increased cellular viability and structural preservation provided by MMCs could advance their application in 3D culture preservation, addressing limitations of conventional cryopreservation in drug testing, regenerative medicine, and cancer research.

Identification of functional biomarkers for personalized nanomedicine in advanced breast cancer in vitro models

Nanomedicines represent promising advanced therapeutics for the enhanced treatment of breast cancer, the primary cause of cancer-related deaths in women; however, the clinical translation of nanomedicines remains challenging. Advanced in vitro models of breast cancer may improve preclinical evaluations and the identification of biomarkers that aid the stratification of patients who would benefit from a given nanomedicine. In this study, we first developed a matrix-embedded breast cancer cell spheroid model representing the extracellular matrix and confirmed the faithful recapitulation of disease aggressiveness in vitro. We then characterized factors influencing nanomedicine drug release (i.e., cathepsin B levels/activity, reactive oxygen species levels, glutathione levels, and cytoplasmic pH values) and evaluated nanomedicine internalization and cytotoxicity evaluation in our spheroid model. We confirmed the reduced-to-oxidized glutathione ratio as a functional biomarker of disulfide linker-containing polypeptide-drug conjugate effectiveness. We then established a biobank of patient-derived breast cancer organoids that recapitulate clinical intra-tumor and inter-tumor heterogeneity as a more advanced model. Analysis in organoids revealed that patient-specific responses to a polypeptide-based nanomedicine correlated with cathepsin B levels, supporting the potential of the functional biomarker for patient-tailored nanomedicine selection. Our findings highlight that exhaustively characterized advanced in vitro models support the evaluation of nanomedicines and the identification of functional biomarkers.

The 3C (Cell Culture, Computer Simulation, Clinical Trial) Solution for Optimizing the 3R (Replace, Reduction, Refine) Framework during Preclinical Research Involving Laboratory Animals

Preclinical research has traditionally utilized laboratory animals to elucidate the safety, tolerability, pharmacokinetics, and pharmacodynamics of new chemical entities prior to human trials. The use of animal models has been pivotal in advancing scientific knowledge and medical breakthroughs, contributing significantly to our understanding of the complex biological processes and human diseases. However, many promising treatments that have demonstrated efficacy in animal studies have failed to translate to human subjects during clinical trials. Consequently, animal testing faces ethical concerns and criticism regarding its predictive reliability for human responses. This has led to the development of 3R principles (Replacement, Reduction, Refinement), introduced in 1959, advocating for alternative methods and improved animal welfare in research. Furthermore, regulatory frameworks and recent legislation, such as the 2022 FDA Modernisation Act, emphasize modern scientific alternatives to traditional animal testing. Emerging approaches, known as the 3Cs-cell culture, computer simulation, and phase 0 clinical trials-offer promising nonanimal solutions that could accelerate drug development and address ethical concerns, potentially rendering preclinical research more humane and efficient.

Quantitative polarization microscopy as a potential tool for quantification of mechanical stresses within 3D matrices

3D mechanical stresses within tissues/extracellular matrices (ECMs) play a significant role in pathological and physiological processes, making their quantification a necessary step to understand the mechanobiological phenomena. Unfortunately, it is rather challenging to quantify these 3D mechanical stresses due to the highly nonlinear and heterogeneous nature of the fibrous matrix. A number of techniques have been developed to address this challenge, including 3D traction force microscopy (TFM), micropillar devices or microparticle-based force sensors; yet, these techniques come with certain drawbacks. Here, we are presenting quantitative polarization microscopy (QPOL) as a non-invasive and label-free technique to quantify mechanical stresses in 3D matrix without a necessity to assume a matrix material model. Taking collagen as a birefringent material, we demonstrated the correlation between the retardance signals obtained by QPOL and the mechanical parameters associated with the 3D collagen hydrogel, i.e. applied external forces and maximum shear stresses. Using cantilever-collagen systems wherein cantilevers applied external loads on the collagen hydrogel, we showed that the retardance signal within loaded collagen positively correlated with the applied load. Also, the retardance signal values within the collagen hydrogel correlated with the maximum shear stress values derived from computational finite element (FE) models. Finally, we obtained the retardance signals around the spheroids of different contractility levels embedded in collagen hydrogel, and the retardance distribution around the spheroids reflected the stress distribution and applied force. This study provides the framework to use QPOL as a tool for quantification of mechanical stresses within 3D ECM. STATEMENT OF SIGNIFICANCE: Mechanical stresses within the 3D extracellular matrix play an important role during physiological and pathological processes. Quantification of such 3D forces is paramount to our understanding of such phenomena and potentially developing therapeutic interventions based on mechanobiological status of the disease. The existing approaches to quantify these 3D mechanical stresses face certain drawbacks such as high computational cost or introduce discontinuities and alteration within the natural 3D microenvironment of the cells. Here, we provide the framework to use quantitative polarization microscopy (QPOL) as an optical-based, non-invasive and computationally efficient technique to quantify the 3D mechanical stresses within the 3D matrix.

Differential Effects of Wheat Bran Antioxidants on the Growth Dynamics of Human Cancer Cells

Wheat bran, rich in phenolic compounds like ferulic acid, possesses notable antioxidant properties that may contribute to cancer treatment strategies. This study examined the effects of hydrolyzed arabinoxylan oligomers (HAOs) linked with ferulic acid from hard wheat bran on three human cancer cell lines: colon cancer (SW480), liver cancer (HepG2), and cervical cancer (HeLa). Cells were cultured in a three-dimensional (3D) 0.5% PGS matrix and exposed to varying concentrations (100, 500, and 1000 μg/mL) of wheat bran antioxidants (WBA) extracts. Results show that WBA inhibited growth of SW480 cells, significantly reducing spheroid expansion and promoting dehydration. In contrast, HepG2 cells exhibited increased growth under WBA treatment, suggesting a non-toxic, growth-enhancing effect. No significant changes were observed in HeLa cell growth, with cell viability remaining high across all treatments. These findings highlight the selective influence of WBA on cancer cell behavior, underscoring its potential for targeted, personalized cancer therapies. This study provides valuable insights into the application of antioxidant-rich compounds for modulating specific cancer cell dynamics, paving the way for novel therapeutic approaches.

Engineering a three-dimensional liver steatosis model

Liver transplantation is the key treatment for liver failure, yet organ scarcity, exacerbated by high discard rates of steatotic livers, leads to high waitlist mortality. Preclinical models of steatosis are necessary to understand the pathophysiology of the disease and to develop pharmacological interventions to decrease disease burden and liver discard rate. In this paper, we develop an expedited 3D steatotic organoid model containing primary human hepatocytes and non-parenchymal cells. We present our iterative approach as we transition from 2D to 3D models and from immortalized to primary cells to optimize conditions for the development of a 3D human steatosis model. Both primary cell aggregation and steatosis induction time were reduced from the standard, 5-7 days, to 2 days. Our 3D model incorporates human primary hepatocytes from discarded liver tissues, which have not been used in organoids previously due to their rapid loss of phenotype in culture. After optimizing our steatosis induction media there was a mix of macro- and micro-steatosis in these primary hepatocytes which is consistent with the human pathology. Our approach achieves a model reflective of the liver pathology, preserving cellular phenotypes and viability while exhibiting markers of oxidative stress, a key factor contributing to complications in the transplantation of steatotic livers.

Amyloidogenesis promotes HSF1 activity enhancing cell survival during breast cancer metastatic colonization

Breast cancer is the most commonly diagnosed cancer among women and the second leading cause of cancer deaths in women. A majority of these breast cancer deaths are due to metastasis, which occurs when primary tumor cells invade into the blood stream to travel and colonize at distant organ sites. Metastatic colonization is the rate-limiting step of metastasis. Heat shock factor 1 (HSF1) is a transcription factor that has been shown to be involved in promoting malignancy with a function in metastatic dissemination due to its contribution to promoting epithelial-to-mesenchymal transition. The role of HSF1 in colonization is unclear. In this study, we observed that HSF1 was essential for metastatic colonization. Consistent with these findings, we also observed that HSF1 was more active in human metastatic tumors compared to primary tumors. HSF1 was also seen to be activated during in vitro colony formation, which was accompanied by increases in amyloid beta (Aβ) fibrils, which was also observed in human metastatic tumors. Aβ fibrils led to HSF1 activation and depletion or inhibition of HSF1 led to increases in Aβ fibrils. HSF1 inhibition with small molecule inhibitors suppressed in vitro colony formation and mammosphere growth of metastatic breast cancer cells. These results suggest that colonization increases Aβ fibril formation that subsequently activates HSF1 as a cell survival mechanism that is essential for metastatic initiation and outgrowth.

Circulating exosomes in pediatric obstructive sleep apnea with or without neurocognitive deficits and their effects on a 3D-blood-brain barrier spheroid model

Obstructive sleep apnea (OSA) in children is linked to cognitive impairments, potentially due to blood-brain barrier (BBB) dysfunction. Exosomes, small vesicles released by most cells, reflect cellular changes. This study examined the effects of exosomes from children with OSA, with or without cognitive deficits, on neurovascular unit (NVU) models. Twenty-six children were categorized into three groups: healthy controls (Cont, n = 6), OSA without cognitive deficits (OSA-NG, n = 10), and OSA with neurocognitive deficits (OSA-POS, n = 10). Plasma exosomes were characterized and applied to human 3D NVU spheroids for 24 h. Barrier integrity, permeability, and angiogenesis were assessed using trans-endothelial electrical resistance (TEER), tight junction integrity, and tube formation assays. Single-nucleus RNA sequencing (snRNA-seq) and bioinformatics, including CellChat analysis, identified intercellular signaling pathways. Results showed that exosomes from OSA-POS children disrupted TEER, increased permeability, and impaired ZO1 staining in spheroids, compared to the other groups. Both OSA-POS and OSA-NG exosomes increased permeability in NVU cells in monolayer and microfluidic BBB models. snRNA-seq analysis further revealed distinct cell clusters and pathways associated with the different groups. This 3D NVU spheroid model provides a robust platform to study BBB properties and the role of exosomes in OSA. These findings suggest that integrating snRNA-seq with exosome studies can uncover mechanisms underlying neurocognitive dysfunction in pediatric OSA, potentially leading to personalized therapeutic approaches.

Benzeneboronic acid-modified hyaluronic acid hydrogel enhances the differentiation of dorsal root ganglion stem cells in a three-dimensional environment

Peripheral nerve injuries (PNI) remain challenging to treat due to limited regeneration capacity and the lack of effective therapeutic scaffolds to support nerve repair. This study aims to develop and evaluate a 3-aminophenylboronic acid-modified hyaluronic acid (HAB) hydrogel as a 3D scaffold to enhance Dorsal root ganglion-derived stem cells (DRGSCs) attachment, migration, and neuronal differentiation for peripheral nerve regeneration. The HAB hydrogel was synthesized through an amidation reaction and characterized using Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR). DRGSCs were cultured in HAB hydrogel, and neuronal differentiation was assessed through immunofluorescence staining, PCR, and multi-electrode array (MEA) recordings. Cytotoxicity, proliferation, and in vivo biocompatibility were evaluated through live/dead staining, CCK-8 assays, and subcutaneous implantation in rats. Transcriptomic analysis was performed to explore gene expression profiles. Our results shown that DRGSCs cultured in HAB hydrogel exhibited significantly improved attachment (78.5 % ± 3.2 % vs. 45.3 % ± 2.8 %, p < 0.05) and migration speeds (21.4 μm/h vs. 12.9 μm/h, p < 0.05) compared to 2D cultures. Neuronal differentiation efficiency, as indicated by Tuj1-positive cells, was also higher (72.6 % ± 4.1 % vs. 42.8 % ± 3.9 %, p < 0.01). RNA sequencing identified 990 differentially expressed genes (627 upregulated, 363 downregulated), with pathways involved in synaptic vesicle cycling, glutamatergic and GABAergic synapses significantly enriched (p < 0.05). Validation revealed that the expression trends of Gnao1 and Grm7 in the plastic petri dish and HAB hydrogel groups were consistent with the RNA sequencing results. In vivo, the hydrogel showed excellent biocompatibility, with reduced TNF-α and IL-1β expression over a 28-day degradation cycle (p < 0.01). The HAB hydrogel provides a supportive 3D microenvironment that enhances DRGSCs differentiation and electrophysiological activity, highlighting its potential as a promising scaffold for peripheral nerve regeneration and neuroregenerative medicine.

Revolutionizing IBD research with on-chip models of disease modeling and drug screening

Inflammatory bowel disease (IBD) comprises chronic inflammatory conditions with complex mechanisms and diverse manifestations, posing significant clinical challenges. Traditional animal models and ethical concerns in human studies necessitate innovative approaches. This review provides an overview of human intestinal architecture in health and inflammation, emphasizing the role of microfluidics and on-chip technologies in IBD research. These technologies allow precise manipulation of cellular and microbial interactions in a physiologically relevant context, simulating the intestinal ecosystem microscopically. By integrating cellular components and replicating 3D tissue architecture, they offer promising models for studying host-microbe interactions, wound healing, and therapeutic approaches. Continuous refinement of these technologies promises to advance IBD understanding and therapy development, inspiring further innovation and cross-disciplinary collaboration.

In vitro 3D modeling of colorectal cancer: the pivotal role of the extracellular matrix, stroma and immune modulation

Colorectal cancer (CRC) is a leading global cancer with high mortality, especially in metastatic cases, with limited therapeutic options. The tumor microenvironment (TME), a network comprising various immune cells, stromal cells and extracellular (ECM) components plays a crucial role in influencing tumor progression and therapy outcome. The genetic heterogeneity of CRC and the complex TME complicates the development of effective, personalized treatment strategies. The prognosis has slowly improved during the past decades, but metastatic CRC (mCRC) is common among patients and is still associated with low survival. The therapeutic options for CRC differ from those for mCRC and include surgery (mostly for CRC), chemotherapy, growth factor receptor signaling pathway targeting, as well as immunotherapy. Malignant CRC cells are established in the TME, which varies depending on the primary or metastatic site. Herein, we review the role and interactions of several ECM components in 3D models of CRC and mCRC tumor cells, with an emphasis on how the TME affects tumor growth and treatment. This comprehensive summary provides support for the development of 3D models that mimic the interactions within the TME, which will be essential for the development of novel anticancer therapies.

Mitochondrial Oxygen Consumption and Immunocytochemistry of Human Dental Pulp Stem Cell Following 808 nm PBM Therapy: A 3D Cell Culture Study

This study investigated the impact of 808 nm laser photobiomodulation (PBM) on mitochondrial respiration and osteogenic protein expression (OCN, OPN, ALP, RUNX2, COL-1, BMP-2) in human dental pulp stem cells (hDPSCs) within a 3D hydrogel model. hDPSCs were isolated from third molars and maintained under hypoxic conditions. Cells received PBM at 5 and 15 J/cm2 using an 808 nm diode laser. The study showed that 808 nm PBM can alter mitochondrial respiration, with 5 J/cm2 enhancing osteogenic protein expression (OCN, ALP, OPN, RUNX2) but failing to sustain BMP-2 at 24 h. In contrast, 15 J/cm2 induced stronger upregulation and prolonged BMP-2 expression, suggesting an optimal dose for sustained osteogenic activity. BMP-2 was later downregulated, and COL-1 remained unchanged post-PBM. Importantly, this study indicates the dose-specific PBM modulation of mitochondrial respiration and protein expression, but further research is required to optimize treatment protocols.

The potential of brain organoids in addressing the heterogeneity of synucleinopathies

Synucleinopathies are a group of diseases characterized by neuronal and glial accumulation of α-synuclein (aSyn) linked with different clinical presentations, including Parkinson's disease (PD), Parkinson's disease with dementia (PDD), Dementia with Lewy Bodies (DLB) and Multiple system atrophy (MSA). Interestingly, the structure of the aSyn aggregates can vary across different synucleinopathies. Currently, it is unclear how the aSyn protein can aggregate into diverse structures and affect distinct cell types and various brain regions, leading to different clinical symptoms. Recent advances in induced pluripotent stem cells (iPSCs)-based brain organoids (BOs) technology provide an unprecedented opportunity to define the etiology of synucleinopathies in human brain cells within their three-dimensional (3D) context. In this review, we will summarize current advances in investigating the mechanisms of synucleinopathies using BOs and discuss the scope of this platform to define mechanisms underlining the selective vulnerability of cell types and brain regions in synucleinopathies.

Imaging 3D cell cultures with optical microscopy

Three-dimensional (3D) cell cultures have gained popularity in recent years due to their ability to represent complex tissues or organs more faithfully than conventional two-dimensional (2D) cell culture. This article reviews the application of both 2D and 3D microscopy approaches for monitoring and studying 3D cell cultures. We first summarize the most popular optical microscopy methods that have been used with 3D cell cultures. We then discuss the general advantages and disadvantages of various microscopy techniques for several broad categories of investigation involving 3D cell cultures. Finally, we provide perspectives on key areas of technical need in which there are clear opportunities for innovation. Our goal is to guide microscope engineers and biomedical end users toward optimal imaging methods for specific investigational scenarios and to identify use cases in which additional innovations in high-resolution imaging could be helpful.

Small molecules direct the generation of ameloblast-like cells from human embryonic stem cells

BACKGROUND

Ameloblasts present a promising avenue for the investigation of enamel and tooth regeneration. Previous protocols for directing the differentiation of human embryonic stem cells (hESCs) into dental epithelial (DE) cells involving the need for additional cells, conditional medium, and the use of costly cytokines. Importantly, ameloblasts have not been generated from hESCs in previous studies. Hence, we aimed to identify defined differentiation conditions that would solely utilize small molecules to achieve the production of ameloblasts.

METHODS

We developed a three-step strategy entailing the progression of hESCs through non-neural ectoderm (NNE) and DE to generate functional ameloblasts in vitro. Initially, the NNE fate was induced from hESCs using a 6-day differentiation protocol with 1 µmol/L Retinoic acid (RA). Subsequently, the NNE lineage was differentiated into DE by employing a combination of 1 µmol/L LDN193189 (a BMP signaling inhibitor) and 1 µmol/L XAV939 (a WNT signaling inhibitor). In the final phase, 3 µmol/L CHIR99021 (a WNT signaling activator) and 2 µmol/L DAPT (a NOTCH signaling inhibitor) were utilized to achieve the fate of ameloblasts from DE cells. Three-dimensional cultures were investigated to enhance the ameloblast differentiation ability of the induced DE cells. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunofluorescence were conducted to assess the expression of lineage-specific markers. Alizarin Red S (ARS) staining was performed to evaluate the formation of mineralization nodules.

RESULTS

The application of RA facilitated the efficient generation of NNE within a six-day period. Subsequently, upon stimulation with LDN193189 and XAV939, a notable emergence of DE cells was observed on the eighth days. By the tenth day, ameloblast-like cells derived from hESCs were generated. Upon cultivation in spheroids, these cells exhibited elevated levels of ameloblast markers AMBN and AMELX expression, suggesting that spheroid culture augments the differentiation of ameloblasts.

CONCLUSION

We established an efficient small molecule-based method to differentiate hESCs into ameloblast-like cells through the concerted modulation of RA, BMP, WNT, and NOTCH signaling pathways, potentially advancing research in enamel and tooth regeneration.

Progressive Deactivation of Hydroxylases Controls Hypoxia-Inducible Factor-1α-Coordinated Cellular Adaptation to Graded Hypoxia

Graded hypoxia is a common microenvironment in malignant solid tumors. As a central regulator in the hypoxic response, hypoxia-inducible factor-1 (HIF-1) can induce multiple cellular processes including glycolysis, angiogenesis, and necroptosis. How cells exploit the HIF-1 pathway to coordinate different processes to survive hypoxia remains unclear. We developed an integrated model of the HIF-1α network to elucidate the mechanism of cellular adaptation to hypoxia. By numerical simulations and bifurcation analysis, we found that HIF-1α is progressively activated with worsening hypoxia due to the sequential deactivation of the hydroxylases prolyl hydroxylase domain enzymes and factor inhibiting HIF (FIH). Bistable switches control the activation and deactivation processes. As a result, glycolysis, immunosuppression, angiogenesis, and necroptosis are orderly elicited in aggravating hypoxia. To avoid the excessive accumulation of lactic acid during glycolysis, HIF-1α induces monocarboxylate transporter and carbonic anhydrase 9 sequentially to export intracellular hydrogen ions, facilitating tumor cell survival. HIF-1α-induced miR-182 facilitates vascular endothelial growth factor production to promote angiogenesis under moderate hypoxia. The imbalance between accumulation and removal of lactic acid in severe hypoxia may result in acidosis and induce cell necroptosis. In addition, the deactivation of FIH results in the destabilization of HIF-1α in anoxia. Collectively, HIF-1α orchestrates the adaptation of tumor cells to hypoxia by selectively inducing its targets according to the severity of hypoxia. Our work may provide clues for tumor therapy by targeting the HIF-1 pathway.

3D cell culture models: how to obtain and characterize the main models

For many years, the gold standard in the study of malignant tumors has been the in vitro culture of tumor cells, in vivo xenografts or genetically modified animal models. Meanwhile, three-dimensional cell models (3D cultures) have been added to the arsenal of modern biomedical research. 3D cultures reproduce tissue-specific features of tissue topology. This makes them relevant tissue models in terms of cell differentiation, metabolism and the development of drug resistance. Such models are already being used by many research groups for both basic and translational research, and may substantially reduce the number of animal studies, for example in the field of oncological research. In the current literature, 3D cultures are classified according to the technique of their formation (with or without a scaffold), cultivation conditions (static or dynamic), as well as their cellular organization and function. In terms of cellular organization, 3D cultures are divided into "spheroid models", "organoids", "organs-on-a-chip" and "microtissues". Each of these models has its own unique features, which should be taken into account when using a particular model in an experiment. The simplest 3D cultures are spheroid models which are floating spherical cell aggregates. An organoid is a more complex 3D model, in which a self-organizing 3D structure is formed from stem cells (SCs) capable of self-renewal and differentiation within the model. Organ-on-a-chip models are chips of microfluidic systems that simulate dynamic physical and biological processes found in organs and tissues in vitro. By combining different cell types into a single structure, spheroids and organoids can act as a basis for the formation of a microtissue - a hybrid 3D model imitating a specific tissue phenotype and containing tissue-specific extracellular matrix (ECM) components. This review presents a brief history of 3D cell culture. It describes the main characteristics and perspectives of the use of "spheroid models", "organoids", "organ-on-a-chip" models and "microtissues" in immune oncology research of solid tumors.

Genes and proteins expression profile of 2D vs 3D cancer models: a comparative analysis for better tumor insights

When juxtaposed with 2D cell culture models, multicellular tumor spheroids demonstrate a capacity to faithfully replicate certain features inherent to solid tumors. These include spatial architecture, physiological responses, the release of soluble mediators, patterns of gene expression, and mechanisms of drug resistance. The morphological and behavioural similarities between 3D-cultured cells and cells within tumor masses highlight the potential of these models in studying cancer biology and drug responses. The liquid overlay method, hanging drop technique, and ultra-low adhesion plates are among the various methods for generating tumor spheroids, each with its advantages and applications. Gene expression studies, employing advanced methods such as microarrays, suppression subtractive hybridization, qRT-PCR, and mass-spectrometry-based proteomics revealed distinct expression patterns in 3D spheroids compared to 2D cultures, uncovering upregulation and downregulation of genes associated with tumor development, metastasis, and drug resistance. Protein expression studies identified alterations in key signaling pathways, metabolic characteristics, and phosphorylation levels, highlighting the impact of 3D culture on cellular responses. This study explores genes and proteins expression variations in various cancer cell lines cultivated in 3D spheroids, shedding light on the complexity of interactions in a more tumor-mimicking environment. The fusion of these analytical approaches not only advances scientific understanding but also holds promise for the development of more effective cancer treatments.

In vivo and In vitro assessment of the retinal toxicity of polystyrene nanoplastics

Plastic pollution has emerged as a critical global environmental challenge, yet the effects of the ingested plastic particles on ocular health remain largely unexplored. In this study, we investigated the impact of orally ingested polystyrene nanoplastics (PS-NPs) on the mouse retina. The in vivo experimental results showed that PS-NPs could penetrate the mouse retina within 2 h after gavage. Their levels increased at 4 h and remained detectable up to 24 h post-gavage. Prolonged exposure (28 days) to PS-NPs might disrupt the tight junctions of the inner blood-retinal barrier (iBRB). Moreover, PS-NPs induced oxidative stress in the retina by downregulating the expression of Nrf2 and HO-1, and potentially promoted apoptosis via the upregulation of Cleaved caspase 3. Additionally, we used human retinal microvascular endothelial cells (HRMECs) to model the iBRB and employed a human retinal pigment epithelial cell line (ARPE-19) to assess the potential toxicity of PS-NPs on the human retina. Our results indicated that PS-NPs penetrated and disrupted the simulated iBRB, inducing oxidative stress and promoting apoptosis in ARPE-19 cells. This study provides critical insights into the potential risks of ingested PS-NPs to retinal health and offers novel perspectives on the broader implications of plastic pollution for humans.

Parkinson's Disease Modeling Using Directly Converted 3D Induced Dopaminergic Neuron Organoids and Assembloids

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons and the accumulation of α-synuclein aggregates, yet current models inadequately mimic the complex human brain environment. Recent advances in brain organoid models offer a more physiologically relevant platform for studying PD, however, iPSC-derived brain organoids require long maturation times and may not accurately represent the aged brain's epigenetics and cellular contexts, limiting their applicability for modeling late-onset diseases like PD. In this study, a novel approach for generating 3D-induced dopaminergic (iDA) neuron organoids directly from human fibroblasts is presented. It is confirmed that these 3D iDA organoids more closely resemble the aged human brain and accurately replicate PD pathologies. Furthermore, this model is extended by incorporating astrocytes to create 3D iDA neuron-astrocyte assembloids, recognizing the critical role of glial cells in neurodegenerative processes. It is identified that PD assembloids incorporating control astrocytes with A53T mutant iDAs demonstrated the neuroprotective effects of healthy astrocytes. In contrast, A53T mutant astrocytes progressively contributed to neuronal degeneration and synucleinopathy in 3D-iDA assembloids. These findings suggest that directly converted 3D-iDA organoids and assembloids provide a robust and physiologically relevant model for studying PD pathogenesis and evaluating therapeutic interventions.

A High-Throughput, Three-Dimensional Multiple Myeloma Model Recapitulating Tumor-Stroma Interactions for CAR-Immune Cell-Mediated Cytotoxicity Assay

Background

Multiple myeloma (MM) is characterized by an excessive proliferation of clonal plasma cells in the bone marrow (BM). Components in BM niche contribute to the immunosuppressive tumor microenvironment (TME), but three-dimensional (3D) MM models that recreate the complex TME and enable high-throughput cytotoxicity assay of chimeric antigen receptor (CAR)-engineered immune cells are still lacking.

Methods

Stable, luciferase (Luc)-labeled target MM cells were generated using Luc/RFP dual reporter system to track MM growth. 3D spheroids were formed in a 96-well plate in the presence or absence of cancer-associated fibroblast (CAF)-like stromal cells activated by MM-derived conditioned medium and the cytotoxicity of CAR-immune cells, which were represented by third-generation anti-CD138 CAR-NK-92 cells, was evaluated by luciferase assay using a multimode microplate reader. Immune cell infiltration was visualized under a fluorescence microscope by using multiple fluorescent dyes.

Results

We first showed that luciferase assay provides a relatively simple and robust means to specifically monitor Luc-labeled tumor cell growth in a coculture system, allowing the high-throughput assessment of CAR-immune cytotoxicity. Through this assay, we demonstrated that CAF-like stromal cells impaired NK cell effector function in 2D culture and 3D spheroids, likely via paracrine signaling and physical barrier function. Importantly, we showed that 3D spheroids consisting of MM cells and CAF-like stromal cells provide a more comprehensive, physiologically relevant immuno-oncology model. Our established model could also be used to investigate the trafficking and infiltration of immune cells into the core of spheroids. Herein, we showed that CAR incorporation did improve the ability of NK cells to infiltrate 3D spheroids.

Conclusion

Our established 3D spheroid model, which partially recapitulates the complex TME with immunosuppressive environment, is suitable for high-throughput screening of CAR-immune cytotoxicity and could be important in accelerating immuno-oncology drug discovery for MM since there is a pressing need to establish innovative CAR-immune cells.

Pancreatic 3D Organoids and Microfluidic Systems-Applicability and Utilization in Surgery: A Literature Review

Background: Pancreatic organoids are a rapidly advancing field of research with new discoveries being made every day. A literature review was performed to answer the question of how relevant 3D pancreatic organoids are for surgery. Materials and Methods: We started our investigation by identifying articles in PubMed within the last 5 years using the keywords (("pancreatic organoid", OR "organ-on-a-chip", OR "pancreatic chip" OR "3D culture methods") AND pancreatic surgery). Only English articles were included in this literature review. This literature review was performed in a non-systematic way; articles were chosen without a predetermined protocol of inclusion and were based on the aim of the review. Results and Conclusions: There are many promising innovations in the field of 3D cultures. Drug sensitivity testing in particular holds great potential for surgical application. For locally advanced PDAC, EUS-FNB obtained cancer tissue can be cultured as organoids, and after 4 weeks, neoadjuvant treatment could be adjusted for each patient individually. Utilizing this approach could increase the number of R0 resections and possibly cure the disease. Furthermore, microfluidic devices, as a platform for pancreatic islet pre-transplant evaluation or cultivation of beta cells derived from HiPSC in vitro, promise broad application of islet transplantation to T1DM patients in the near future.

3D tumor cultures for drug resistance and screening development in clinical applications

Tumor drug resistance presents a growing challenge in medical practice, particularly during anti-cancer therapies, where the emergence of drug-resistant cancer cells significantly complicates clinical treatment. In recent years, three-dimensional (3D) tumor culture technology, which more effectively simulates the in vivo physiological environment, has gained increasing attention in tumor drug resistance research and clinical applications. By mimicking the in vivo cellular microenvironment, 3D tumor culture technology not only recapitulates cell-cell interactions but also more faithfully reproduces the biological effects of therapeutic agents. Consequently, 3D tumor culture technology is emerging as a crucial tool in biomedical and clinical research. We summarize the benefits of 3D culture models and organoid technology, explore their application in the realm of drug resistance, drug screening, and personalized therapy, and discuss their potential application prospects and challenges in clinical transformation, with the aim of providing insights for optimizing cancer treatment strategies and advancing precision therapy.

Multiparametric physicochemical analysis of a type 1 collagen 3D cell culture model using light and electron microscopy and mass spectrometry imaging

Three-dimensional cell culture systems underpin cell-based technologies ranging from tissue scaffolds for regenerative medicine to tumor models and organoids for drug screening. However, to realise the full potential of these technologies requires analytical methods able to capture the diverse information needed to characterize constituent cells, scaffold components and the extracellular milieu. Here we describe a multimodal imaging workflow which combines fluorescence, vibrational and second harmonic generation microscopy with secondary ion mass spectrometry imaging and transmission electron microscopy to analyse the morphological, chemical and ultrastructural properties of cell-seeded scaffolds. Using cell nuclei as landmarks we register fluorescence with label-free optical microscopy images and high mass resolution with high spatial resolution secondary ion mass spectrometry images, with an accuracy comparable to the intrinsic spatial resolution of the techniques. We apply these methods to investigate relationships between cell distribution, cytoskeletal morphology, scaffold fiber organisation and biomolecular composition in type I collagen scaffolds seeded with human dermal fibroblasts.

Clinical Applications of Targeted Nanomaterials

Targeted nanomaterials are at the forefront of advancements in nanomedicine due to their unique and versatile properties. These include nanoscale size, shape, surface chemistry, mechanical flexibility, fluorescence, optical behavior, magnetic and electronic characteristics, as well as biocompatibility and biodegradability. These attributes enable their application across diverse fields, including drug delivery. This review explores the fundamental characteristics of nanomaterials and emphasizes their importance in clinical applications. It further delves into methodologies for nanoparticle programming alongside discussions on clinical trials and case studies. We discussed some of the promising nanomaterials, such as polymeric nanoparticles, carbon-based nanoparticles, and metallic nanoparticles, and their role in biomedical applications. This review underscores significant advancements in translating nanomaterials into clinical applications and highlights the potential of these innovative approaches in revolutionizing the medical field.

A novel approach for engineering DHCM/GelMA microgels: application in hepatocellular carcinoma cell encapsulation and chemoresistance research

Liver cancer, a highly aggressive malignancy, continues to present significant challenges in therapeutic management due to its pronounced chemoresistance. This resistance, which undermines the efficacy of conventional chemotherapy and targeted therapies, is driven by multifaceted mechanisms, with increasing emphasis placed on the protective role of the tumor microenvironment (TME). The hepatocellular carcinoma extracellular matrix (ECM), a primary non-cellular component of the TME, has emerged as a critical regulator in cancer progression and drug resistance, particularly in hepatocellular carcinoma cell (HCC). In this study, a hybrid biomimetic hydrogel was engineered by integrating decellularized hepatocellular carcinoma matrix (DHCM) with gelatin methacrylate (GelMA) precursors. This composite DHCM/GelMA hydrogel was designed to replicate the physicochemical and functional properties of the hepatocellular carcinoma ECM, thereby offering a biomimetic platform to explore the interactions between HCCs and their microenvironment. Leveraging a custom-designed microfluidic 3D printing platform, we achieved high-throughput fabrication of HCC-encapsulated DHCM/GelMA microgels, characterized by enhanced uniformity, biocompatibility, and scalability. These microgels facilitated the construction of hepatocellular carcinoma microtissues, which were subsequently employed for chemoresistance studies. Our findings revealed that DHCM/GelMA microgels closely mimic the hepatocellular carcinoma tumor microenvironment, effectively recapitulating key features of ECM-mediated drug resistance. Mechanistic studies further demonstrated that DHCM significantly upregulates the expression of Aquaporin 3 (AQP3) in the encapsulated HCCs. This upregulation potentially activates mTOR signaling-associated autophagy pathways, thereby enhancing chemoresistance in HCCs. These biomimetic models provide a robust and versatile platform for studying the underlying mechanisms of drug resistance and evaluating therapeutic interventions. This innovative approach highlights the potential of DHCM/GelMA microgels as a transformative tool in cancer-associated tissue engineering and anticancer drug screening. By enabling detailed investigations into the role of ECM in chemoresistance, this study contributes to advancing therapeutic research and offers promising strategies to overcome drug resistance, ultimately improving clinical outcomes in liver cancer treatment.

The Effects of Electrical Stimulation on a 3D Osteoblast Cell Model

Electrical stimulation has been used with tissue engineering-based models to develop three-dimensional (3D), dynamic, research models that are more physiologically relevant than static two-dimensional (2D) cultures. For bone tissue, the effect of electrical stimulation has focused on promoting healing and regeneration of tissue to prevent bone loss. However, electrical stimulation can also potentially affect mature bone parenchymal cells such as osteoblasts to guide bone formation and the secretion of paracrine or endocrine factors. Due to a lack of physiologically relevant models, these phenomena have not been studied in detail. In vitro electrical stimulation models can be useful for gaining an understanding of bone physiology and its effects on paracrine tissues under different physiological and pathological conditions. Here, we use a 3D, dynamic, in vitro model of bone to study the effects of electrical stimulation conditions on protein and gene expression of SaOS-2 human osteosarcoma osteoblast-like cells. We show that different stimulation regimens, including different frequencies, exposure times, and stimulation patterns, can have different effects on the expression and secretion of the osteoblastic markers alkaline phosphatase and osteocalcin. These results reveal that electrical stimulation can potentially be used to guide osteoblast gene and protein expression.

Heart Scar-In-A-Dish: Tissue Culture Platform to Study Myocardial Infarct Healing In Vitro

Myocardial Infarction (MI) is a major contributor to morbidity and mortality, wherein blood flow is blocked to a portion of the left ventricle and leads to myocardial necrosis and scar formation. Cardiac remodeling in response to MI is a major determinant of patient prognosis, so many therapies are under development to improve infarct healing. Part of this development involves in vitro therapy screening which can be accelerated by engineered heart tissues (EHTs). Unfortunately, EHTs often over-simplify the infarcted tissue microarchitecture by neglecting spatial variation found in infarcted ventricles. MI results in a spatially heterogeneous environment with an infarct zone composed mostly of extracellular matrix (ECM) and cardiac fibroblasts, contrasted with a remote (non-infarct) zone composed mostly of cardiomyocytes, and a border zone transitioning in between. The heterogeneous structure is accompanied by heterogeneous mechanics where the passive infarct zone is cyclically stretched under tension as the remote zone cyclically contracts with every heartbeat. We present an in vitro 3-dimensional tissue culture platform focused on mimicking the heterogeneous mechanical environment of post-infarct myocardium. Herein, EHTs were subjected to a cryowound injury to induce localized cell death in a central portion of beating tissues composed of neonatal rat cardiomyocytes and cardiac fibroblasts. After injury, the remote zone continued to contract (i.e., negative strains) while the wounded zone was cyclically stretched (i.e., positive tensile strains) with intermediate strains in the border zone. We also observed increased tissue stiffnesses in the wounded zone and border zone following injury, while the remote zone did not show the same stiffening. Collectively, this work establishes a novel in vitro platform for characterizing myocardial wound remodeling with both spatial and temporal resolution, contributing to a deeper understanding of MI and offering insights for potential therapeutic approaches.

Chitosan/alginate polyelectrolyte complex hydrogels by additive manufacturing for in vitro 3D ovarian cancer modeling

Polyelectrolyte complexes (PECs) are self-assembled systems formed from oppositely charged polymers, used to create hydrogels for cell culture. This work was aimed at additive manufacturing 3D hydrogels made of a PEC between chitosan (Cs) and alginate, as well as their investigation for in vitro 3D ovarian cancer modeling. PEC hydrogels stability in cell culture medium demonstrated their suitability for long-term cell culture applications. Higher in vitro viability of two human ovarian cancer cell lines was detected at different time points on PEC hydrogels than on Cs hydrogels, used as a control. In addition, during the 63-day culture experiment, cells effectively colonized the scaffolds while retaining their aggressive tumor characteristics. A significantly lower sensitivity to cisplatin and eugenol, also when combined, was observed in the developed 3D ovarian cancer models, in comparison to what was achieved in relevant 2D cell cultures. The obtained results demonstrated therefore the suitability of the developed scaffolds for in vitro investigation of tumor modeling.

Bone microphysiological models for biomedical research

Bone related disorders are highly prevalent, and many of these pathologies still do not have curative and definitive treatment methods. This is due to a complex interplay of multiple factors, such as the crosstalk between different tissues and cellular components, all of which are affected by microenvironmental factors. Moreover, these bone pathologies are specific, and current treatment results vary from patient to patient owing to their intrinsic biological variability. Current approaches in drug development to deliver new drug candidates against common bone disorders, such as standard two-dimensional (2D) cell culture and animal-based studies, are now being replaced by more relevant diseases modelling, such as three-dimension (3D) cell culture and primary cells under human-focused microphysiological systems (MPS) that can resemble human physiology by mimicking 3D tissue organization and cell microenvironmental cues. In this review, various technological advancements for in vitro bone modeling are discussed, highlighting the progress in biomaterials used as extracellular matrices, stem cell biology, and primary cell culture techniques. With emphasis on examples of modeling healthy and disease-associated bone tissues, this tutorial review aims to survey current approaches of up-to-date bone-on-chips through MPS technology, with special emphasis on the scaffold and chip capabilities for mimicking the bone extracellular matrix as this is the key environment generated for cell crosstalk and interaction. The relevant bone models are studied with critical analysis of the methods employed, aiming to serve as a tool for designing new and translational approaches. Additionally, the features reported in these state-of-the-art studies will be useful for modeling bone pathophysiology, guiding future improvements in personalized bone models that can accelerate drug discovery and clinical translation.

MTMR6 downregulation contributes to cisplatin resistance in oral squamous cell carcinoma

BACKGROUND

The therapeutic effectiveness of cisplatin, a widely used chemotherapy drug for oral squamous cell carcinoma (OSCC), is often compromised by resistance, making it difficult to predict treatment outcomes. The role of myotubularin and myotubularin-related (MTMR) genes in cisplatin resistance remains unclear. We aimed to elucidate the molecular mechanisms underlying MTMR6 with cisplatin resistance in OSCC.

METHODS

MTMR6 expression was compared between UMSCC1 and cisplatin-resistant UM-Cis cells. Gain- and loss-of-function experiments involving MTMR6 was performed to evaluate its impact on cisplatin resistance. The regulatory role of hsa-miR-544a on MTMR6 expression was explored via antagomir and miRNA mimic assays. The relationship between MTMR6 protein levels and cisplatin sensitivity was assessed in OSCC patient tissues classified as sensitive or resistant to cisplatin monotherapy. A survival analysis based on The Cancer Genome Atlas (TCGA) head and neck squamous cell carcinoma (HNSCC) dataset was performed to evaluate the correlation between MTMR6 expression and patient outcomes following cisplatin treatment. In vivo cisplatin resistance was examined using mouse xenografts derived from MTMR6-knockdown UMSCC1 cells.

RESULTS

MTMR6 expression was markedly reduced in cisplatin-resistant UM-Cis cells compared to UMSCC1 cells. Functional analyses revealed that modulating MTMR6 activity alters cisplatin resistance. A luciferase assay confirmed that hsa-miR-544a regulates MTMR6 gene expression. Additionally, antagomir and miRNA mimics demonstrated that hsa-miR-544a enhances cisplatin resistance by suppressing MTMR6 expression. In OSCC patient tissues, higher MTMR6 protein levels were associated with cisplatin sensitivity, while cisplatin-resistant tissues had lower MTMR6 expression. Survival analysis of the TCGA HNSCC dataset indicated that low MTMR6 expression correlates with poorer outcomes in cisplatin-treated patients compared to those with high MTMR6 expression. Mouse xenografts derived from MTMR6-knockdown UMSCC1 cells exhibited increased resistance to cisplatin compared to controls.

CONCLUSION

Assessing mRNA levels of MTMR6 and has-miR-544a in biopsy samples could help predict cisplatin responsiveness in OSCC.

Redox/NIR dual-responsive glutathione extended polyurethane urea electrospun membranes for synergistic chemo-photothermal therapy

Despite advancements in cancer treatments, therapies frequently exhibit high cytotoxicity, and surgery remains the predominant method for treating most solid tumors, often with limited success in preventing post-surgical recurrence. Implantable biomaterials, designed to release drugs at a localised site in response to specific stimuli, represent a promising approach for enhancing tumour therapy. In this study, a redox-responsive glutathione extended polyurethane urea (PolyCEGS) was used to produce paclitaxel (PTX) and gold nanorods (AuNRs) loaded electrospun membranes for combined redox/near-infrared (NIR) light-responsive release chemotherapy and hyperthermic effect. Electrospinning conditions were optimized to fabricate AuNR-loaded scaffolds, at three different AuNRs concentrations. The obtained membranes were characterized by scanning electron microscopy (SEM) analyses and photothermal profiles were evaluated by a thermocamera, showing a temperature increase, up to 42.5 °C, when exposed to NIR light (810 nm) at 3 W/cm2. The AuNRs/PTX loaded scaffolds exhibited sustained PTX release, with 15 % released over 30 days and almost 1.8 times more in a simulated reductive environment. Moreover, their excellent photothermal effects and NIR light-triggered release led to significant synergic cytotoxicity in human colon cancer (HCT-116) and human breast cancer (MCF-7) cell lines. This system potentially enables controllable locoregional PTX release at the tumour site post-surgery, preventing recurrence and enhancing cytotoxicity through combined drug and PTT effects, highlighting its potential for future anticancer treatments.

Harnessing cell aggregates for enhanced adeno-associated virus manufacturing: Cultivation strategies and scale-up considerations

The possibility to produce recombinant adeno-associated virus (rAAV) by adherent HEK293T cells was studied in a stirred tank bioreactor (STR) culture of cell aggregates. A proof-of-concept of rAAV production was successfully demonstrated in a process where single cells were first expanded, then cell aggregates were formed by dilution into a different medium 1 day before triple plasmid transfection was conducted. An alternative approach for the STR inoculation using a seed taken from a high cell density perfusion (HCDP) culture was also investigated. It was, however, found that the spent medium of the HCDP inhibited the transfection of HEK293T cell aggregates, which was confirmed when testing with single-cell suspension culture. The formation of aggregates in shaken multi-well plates was also investigated to develop a screening system using the average power input as a scale-down criterion, which revealed that cell aggregates could be generated in 12-well plates, however with a larger size than in a STR. Taking into account the reported higher rAAV production of adherent cells in comparison with single cells for triple-plasmid transfection, HEK293T cell aggregates can possibly surpass single-cell suspension in space-time rAAV yield. The formation of HEK293T cell aggregates in a STR system offers a promising approach for scaling up and intensifying rAAV production by triple-plasmid transfection, in comparison with traditional 2D scale-up methods.

The Secretome of the Inductive Tooth Germ Exhibits Signals Required for Tooth Development

Teeth develop from reciprocal signaling between inductive and receptive cells. The inductive signals for tooth development are initially in the epithelium of the developing branchial arch, but later shift to the underlying mesenchyme of a developing tooth germ. The inductive signals that are needed for tooth development have not yet been fully identified. Our lab previously provided a basis for bioengineering new teeth by separating the tooth germ's epithelial and mesenchyme cells into a single cell population and recombing them. This approach, however, is not clinically applicable as the cells lose their inductive ability when expanded in vitro. In this study, we investigate whether the secretome and small extracellular vehicles (sEV) derived from inductive tooth germ mesenchyme can contribute to inductive signals required for tooth development. To address this, small extracellular vesicles and secretome were purified from inductive tooth germ mesenchyme and characterized. We investigated the proteome of sEV and proteome of inductive tooth germ mesenchyme and the impact of the culture condition and duration on the proteome. Additionally, we investigated the transcriptomic changes in tooth germ epithelium after treatment with sEV from inductive tooth germ mesenchyme. We show that culture duration of inductive tooth germ mesenchyme has an impact on the proteome of sEV purified from these cells. Similarly, culturing these cells in 2D and 3D environments results in different protein content. Proteome unique to sEV derived from inductive shows an association with multiple signaling pathways related to tooth development. Our RNASeq results show that treatment of tooth germ epithelial cells with small extracellular vesicles derived from inductive tooth germ mesenchyme results in an increased expression of some of the known odontogenic genes. Whilst further analysis is required to harvest the full potential of these sEV, our results suggests that extracellular vehicles contribute to signals required during tooth development, potentially through modulation of cellular metabolism and ECM organization.

A multi-stage weakly supervised design for spheroid segmentation to explore mesenchymal stem cell differentiation dynamics

There is a growing interest in utilizing 3D culture models for stem cell and cancer cell research due to their closer resemblance to in vivo environments. In this study, human mesenchymal stem cells (MSCs) were cultured using adipocytes and osteocytes as differentiative mediums on varying concentrations of chitosan substrate. Light microscopy was employed to capture cell images from the first day to the 21st day of differentiation. Accurate image segmentation is crucial for analyzing the morphological features of the spheroids during the experimental period and for understanding MSC differentiation dynamics for therapeutic applications. Therefore, we developed an innovative, weakly supervised model, aided by convolutional neural networks, to perform label-free spheroid segmentation. Since obtaining pixel-level ground truth labels through manual annotation is labor-intensive, our approach improves the overall quality of the ground-truth map by incorporating a multi-stage process within a weakly supervised learning framework. Additionally, we developed a robust learning scheme for spheroid detection, providing a reliable foundation to study MSC differentiation dynamics. The proposed framework was systematically evaluated using low-resolution microscopic data and challenging, noisy backgrounds. The experimental results demonstrate the effectiveness of our segmentation approach in accurately separating the spheroid from the background. Furthermore, it achieves performance comparable to fully supervised state-of-the-art approaches. To quantitatively evaluate our algorithm, extensive experiments were conducted using available annotated data, confirming the reliability and robustness of our method. Our computationally extracted features can confirm the experimental results regarding alterations in MSC viability, attachment, and differentiation dynamics among the substrates with three concentrations of chitosan used. We observed the formation of more compact spheroids with higher solidity and convex area, resulting improved cell attachment and viability on the 2% chitosan substrate. Additionally, this substrate exhibited a higher propensity for differentiation into osteocytes, as evidenced by the formation of smaller and more ellipsoid spheroids.

"Chitosan biofilms mimic in vivo environments for stem cell culture, advancing therapeutic and fundamental applications.” "Innovative weakly supervised model enables label-free spheroid segmentation in stem cell differentiation studies.” "Robust learning scheme achieves accurate spheroid separation, comparable to state-of-the-art approaches.”

Two- and Three-Dimensional Culture Systems: Respiratory In Vitro Tissue Models for Chemical Screening and Risk-Based Decision Making

Risk of lung damage from inhaled chemicals or substances has long been assessed using animal models. However, New Approach Methodologies (NAMs) that replace, reduce, and/or refine the use of animals in safety testing such as 2D and 3D cultures are increasingly being used to understand human-relevant toxicity responses and for the assessment of hazard identification. Here we review 2D and 3D lung models in terms of their application for inhalation toxicity assessment. We highlight a key case study for the Organization for Economic Cooperation and Development (OECD), in which a 3D model was used to assess human toxicity and replace the requirement for a 90-day inhalation toxicity study in rats. Finally, we consider the regulatory guidelines for the application of NAMs and potential use of different lung models for aerosol toxicity studies depending on the regulatory requirement/context of use.

High-throughput microfluidic spheroid technology for early detection of colistin-induced nephrotoxicity with gradient-based analysis

Colistin is essential for treating multidrug-resistant Gram-negative bacterial infections but has significant nephrotoxic side effects. Traditional approaches for studying colistin's nephrotoxicity are challenged by the rapid metabolism of its prodrug, colistin methanesulfonate and the difficulty of obtaining adequate plasma from critically ill patients. To address these challenges, we developed the Spheroid Nephrotoxicity Assessing Platform (SNAP), a microfluidic device that efficiently detects colistin-induced toxicity in renal proximal tubular epithelial cell (RPTEC) spheroids within 48 hours using just 200 μL of patient plasma. Our findings demonstrate that SNAP not only promotes higher expression of kidney-specific markers aquaporin-1 (AQP1) and low-density lipoprotein receptor-related protein 2 (LRP2) compared to traditional two-dimensional (2D) cultures, but also exhibits increased sensitivity to colistin, with significant toxicity detected at concentrations of 50 μg ml-1 and above. Notably, SNAP's non-invasive method did not identify nephrotoxicity in plasma from healthy donors, thereby confirming its physiological relevance and showcasing superior sensitivity over 2D cultures, which yielded false-positive results. In clinical validation, SNAP accurately identified patients at risk of colistin-induced nephrotoxicity with 100% accuracy for both early and late onset and demonstrated a 75% accuracy rate in predicting the non-occurrence of nephrotoxicity. These results underline the potential of SNAP in personalized medicine, offering a non-invasive, precise and efficient tool for the assessment of antibiotic-induced nephrotoxicity, thus enhancing the safety and efficacy of treatments against resistant bacterial infections.

Modelling Endometriosis Using In Vitro and In Vivo Systems

Endometriosis is a chronic inflammatory condition characterised by the presence of endometrium-like tissue outside the uterus. Despite its high prevalence and recent advances in molecular science, many aspects of endometriosis and its pathophysiology are still poorly understood. Previously, in vitro and in vivo modelling have been instrumental in establishing our current understanding of endometriosis. As the field of molecular science and the advance towards personalised medicine is ever increasing, more sophisticated models are continually being developed. These hold great potential to provide more intricate knowledge of the underlying pathophysiology and facilitate investigations into potential future approaches to diagnosis and treatment. This review provides an overview of different in vitro and in vivo models of endometriosis that are pertinent to establishing our current understanding. Moreover, we discuss new cross-cutting approaches to endometriosis modelling, such as the use of microfluidic cultures and 3D printing, which have the potential to shape the future of endometriosis research.

Exploring the effects of gut microbiota on cholangiocarcinoma progression by patient-derived organoids

BACKGROUND

Recent research indicates a role of gut microbiota in development and progression of life-threatening diseases such as cancer. Carcinomas of the biliary ducts, the so-called cholangiocarcinomas, are known for their aggressive tumor biology, implying poor prognosis of affected patients. An impact of the gut microbiota on cholangiocarcinoma development and progression is plausible due to the enterohepatic circulation and is therefore the subject of scientific debate, however evidence is still lacking. This review aimed to discuss the suitability of complex cell culture models to investigate the role of gut microbiota in cholangiocarcinoma progression.

MAIN BODY

Clinical research in this area is challenging due to poor comparability of patients and feasibility reasons, which is why translational models are needed to understand the basis of tumor progression in cholangiocarcinoma. A promising approach to investigate the influence of gut microbiota could be an organoid model. Organoids are 3D cell models cultivated in a modifiable and controlled condition, which can be grown from tumor tissue. 3D cell models are able to imitate physiological and pathological processes in the human body and thus contribute to a better understanding of health and disease.

CONCLUSION

The use of complex cell cultures such as organoids and organoid co-cultures might be powerful and valuable tools to study not only the growth behavior and growth of cholangiocarcinoma cells, but also the interaction with the tumor microenvironment and with components of the gut microbiota.

Evaluation of bone-protecting effects of palm carotene mixture in two- and three-dimensional osteoblast/osteoclast co-culture systems

Background: Carotene exists naturally in a complex mixture consisting of alpha (α), beta (β), and gamma (γ)-isoforms. Previous studies investigated the effects of individual carotene isomers on bone rather than their actions in a mixture. Purpose: This study explored the bone-protective properties of palm carotene mixture using both two- and three-dimensional co-culture systems. Study design: The viability of human foetal osteoblasts (hFOB 1.19), viability of human monocytic cell line (THP-1), osteoblast differentiation, osteoclast maturation, bone quality and strength were assessed in two- and three-dimensional co-culture system after treatment of palm carotene mixture. Methods: The viability of hFOB 1.19 and THP-1 was determined on day 1, 3, and 6 following treatment of palm carotene mixture. The osteoblast-osteoclast co-culture (ratio of hFOB 1.19 to THP-1 = 2:1) was treated with palm carotene mixture as well as subjected to alkaline phosphatase (ALP) and tartrate resistant acid phosphatase (TRAP) staining on day 21 to assess the osteoblast proliferation and osteoclast maturation. Dual-energy X-ray absorptiometry, micro-computed tomography, universal testing machine, and bone histomorphometry were used to assess the bone parameters of scaffolds co-cultured with osteoblasts and osteoclasts. Results: Palm carotene mixture (3.13 - 50 μg/mL) increased osteoblast viability. Monocyte viability decreased in lower concentration (3.13 - 12.5 μg/mL) but increased in higher concentration (25 - 50 μg/mL) of palm carotene mixture. Treatment with palm carotene mixture (12.5 µg/mL) demonstrated earlier peak for the ALP-positive area on day 14 but decreased total number of TRAP-positive multinucleated cells on day 21. Palm carotene mixture also increased bone volume and osteoblast number in the three-dimensional co-culture system. Conclusion: Palm carotene mixture potentially exhibits beneficial effects on bone by accelerating osteoblast proliferation and suppressing osteoclast maturation. The findings of current study serve as the basis for the further validation through animal experiments and human trials.

A 3D Cell-Culture System That Uses Nano-Fibrillated Bacterial Cellulose to Prepare a Spherical Formulation of Culture Cells

A 3-dimensional (3D) cell culture is now being actively pursued to accomplish the in vivo-like cellular morphology and biological functions in cell culture. We recently obtained nano-fibrillated bacterial cellulose (NFBC). In this study, we developed a novel NFBC-based 3D cell-culture system, the OnGel method, and the Suspension method. HepG2 human liver cancer cells were cultured via these methods and formed spherical formulations in the optimized condition, 1.0% (w/v) of NFBC in the OnGel method, and 0.06-0.10% (w/v) of NFBC in the Suspension method. Non-cancerous cells such as human-induced pluripotent stem (iPS) cells and human mesenchymal stem cells (MSCs) also formed spherical formulations. It is noteworthy that both the size and cell viability of spheroids prepared via these methods were comparable to those cultured using commercially available 3D cell-culture systems. Both OnGel and Suspension methods are less complicated than the existing 3D cell-culture systems, which is an invaluable advantage for the preparation of cancer spheroids. The NFBC-based 3D cell-culture systems introduced here show great promise as a tool to prepare cultures for cell-derived spheroids for the progress of both in vitro and in vivo studies of the biological functioning of cells.

Direct visualization of emergent metastatic features within an ex vivo model of the tumor microenvironment

Ischemic conditions such as hypoxia and nutrient starvation, together with interactions with stromal cells, are critical drivers of metastasis. These conditions arise deep within tumor tissues, and thus, observing nascent metastases is exceedingly challenging. We thus developed the 3MIC-an ex vivo model of the tumor microenvironment-to study the emergence of metastatic features in tumor cells in a 3-dimensional (3D) context. Here, tumor cells spontaneously create ischemic-like conditions, allowing us to study how tumor spheroids migrate, invade, and interact with stromal cells under different metabolic conditions. Consistent with previous data, we show that ischemia increases cell migration and invasion, but the 3MIC allowed us to directly observe and perturb cells while they acquire these pro-metastatic features. Interestingly, our results indicate that medium acidification is one of the strongest pro-metastatic cues and also illustrate using the 3MIC to test anti-metastatic drugs on cells experiencing different metabolic conditions. Overall, the 3MIC can help dissecting the complexity of the tumor microenvironment for the direct observation and perturbation of tumor cells during the early metastatic process.

Recent Developments in Glioblastoma-On-A-Chip for Advanced Drug Screening Applications

Glioblastoma (GBM) is an aggressive form of cancer, comprising ≈80% of malignant brain tumors. However, there are no effective treatments for GBM due to its heterogeneity and the presence of the blood-brain barrier (BBB), which restricts the delivery of therapeutics to the brain. Despite in vitro models contributing to the understanding of GBM, conventional 2D models oversimplify the complex tumor microenvironment. Organ-on-a-chip (OoC) models have emerged as promising platforms that recapitulate human tissue physiology, enabling disease modeling, drug screening, and personalized medicine. There is a sudden increase in GBM-on-a-chip models that can significantly advance the knowledge of GBM etiology and revolutionize drug development by reducing animal testing and enhancing translation to the clinic. In this review, an overview of GBM-on-a-chip models and their applications is reported for drug screening and discussed current challenges and potential future directions for GBM-on-a-chip models.

The paradigm of stem cell secretome in tissue repair and regeneration: Present and future perspectives

As the number of patients requiring organ transplants continues to rise exponentially, there is a dire need for therapeutics, with repair and regenerative properties, to assist in alleviating this medical crisis. Over the past decade, there has been a shift from conventional stem cell treatments towards the use of the secretome, the protein and factor secretions from cells. These components may possess novel druggable targets and hold the key to profoundly altering the field of regenerative medicine. Despite the progress in this field, clinical translation of secretome-containing products is limited by several challenges including but not limited to ensuring batch-to-batch consistency, the prevention of further heterogeneity, production of sufficient secretome quantities, product registration, good manufacturing practice protocols and the pharmacokinetic/pharmacodynamic profiles of all the components. Despite this, the secretome may hold the key to unlocking the regenerative blockage scientists have encountered for years. This review critically analyses the secretome derived from different cell sources and used in several tissues for tissue regeneration. Furthermore, it provides an overview of the current delivery strategies and the future perspectives for the secretome as a potential therapeutic. The success and possible shortcomings of the secretome are evaluated.

Spheroid Formation and Easy and Stable Control of Stromal Cells Using Multi-inlet Spheroid Generator

Tumor spheroids have been used as a powerful tool for testing anti-cancer drugs or understanding tumors in vivo due to their structural and physiological recapitulation of human solid tumors. Furthermore, when co-cultured with stromal cells, it is much more relevant to tumor in vivo than cancer cell alone, because stromal cells in tumor microenvironment play major roles in cancer progression and drug resistance. This protocol describes how to generate a spheroid with a controlled stromal cell ratio using a multi-inlet spheroid generator.

Developing human upper, lower, and deep lung airway models: Combining different scaffolds and developing complex co-cultures

Advanced in vitro models are crucial for studying human airway biology. Our objective was the development and optimization of 3D in vitro models representing diverse airway regions, including deep lung alveolar region. This initiative was aimed at assessing the influence of selective scaffold materials on distinct airway co-culture models. While PET membranes (30 µm thickness) were unsuitable for alveolar models due to their stiffness and relatively high Young's modulus, a combination of collagenous scaffolds seeded with Calu-3 cells and fibroblasts, showed increased mucus production going from week 1 to week 4 of air lift culture. Meanwhile standard electrospun polymer membrane (50-60 µm thick), which possesses a considerably low modulus of elasticity, offered higher flexibility and supported co-cultures of primary alveolar epithelial (huAEC) and endothelial cells (hEC) in concert with lung biopsy-derived fibroblasts which enhanced maturation of the tissue model. As published, designing human alveolar in vitro models require thin scaffold to mimic the required ultra-thin ECM, in addition to assuring right balanced AT1/AT2 ratio for biomimetic representation. We concluded that co-cultivation of primary/stem cells or cell lines has a higher influence on the function of the airway tissue models than the applied scaffolds.

Characterization of Composite Agarose-Collagen Hydrogels for Chondrocyte Culture

To elucidate the mechanisms of cellular mechanotransduction, it is necessary to employ biomaterials that effectively merge biofunctionality with appropriate mechanical characteristics. Agarose and collagen separately are common biopolymers used in cartilage mechanobiology and mechanotransduction studies but lack features that make them ideal for functional engineered cartilage. In this study, agarose is blended with collagen type I to create hydrogels with final concentrations of 4% w/v or 2% w/v agarose with 2 mg/mL collagen. We hypothesized that the addition of collagen into a high-concentration agarose hydrogel does not diminish mechanical properties. Acellular and cell-laden studies were completed to assess rheologic and compressive properties, contraction, and structural homogeneity in addition to cell proliferation and sulfated glycosaminoglycan production. Over 21 days in culture, cellular 4% agarose-2 mg/mL collagen I hydrogels seeded with primary murine chondrocytes displayed structural and bulk mechanical behaviors that did not significantly alter from 4% agarose-only hydrogels, cell proliferation, and continual glycosaminoglycan production, indicating promise toward the development of an effective hydrogel for chondrocyte mechanotransduction and mechanobiology studies.