Calcein AM Research Articles

Optimizing cell migration assays: Critical roles of fluorescent labeling and chemoattractant gradients.

Cell migration assays, also known as chemotaxis assays, are widely used to measure the migratory capacities of cancer cells, leukocytes, macrophages, and other motile cell types. In these assays, fluorescently labeled cells are seeded onto cell culture inserts with microporous membranes that block light transmission from 490 to 700nm. The migrated cells are then observed and quantified from the bottom of the microporous membrane using a fluorescence microscope. In this study, we conducted cell migration assays using macrophages as the motile cells. We discovered that the commonly employed fluorescent labeling method using calcein acetoxymethyl ester (calcein AM) can lead to the time-dependent attenuation of fluorescent signals in certain cell types during migration assays, potentially compromising assay stability. This study overcame this limitation by utilizing PKH26, which fluorescently labels cell surfaces through a mechanism distinct from that of calcein AM. With this modification, we observed a consistent increase in the number of migrating macrophages over time. We also demonstrated that the gradient of chemoattractants is key to the success of cell migration assays. Our improved protocol provided reliable and stable results for cell migration assays.

Hyperthermia reduces cancer cell invasion and combats chemoresistance and immune evasion in human bladder cancer.

Bladder cancer (BC) is a common malignancy and its most prevalent type is urothelial carcinoma, which accounts for ~90% of all cases of BC. The current treatment options for BC are limited, which necessitates the development of alternative treatment strategies. Hyperthermia (HT), as an adjuvant cancer therapy, is known to improve the efficacy of chemotherapy or radiotherapy. The present study aimed to investigate the anti‑tumor effects of HT on cell survival, invasiveness, chemoresistance and immune evasion in human BC cell lines (5637, T24 and UMUC3). Calcein AM staining was performed to analyze the cytotoxicity of natural killer (NK) cells against human BC cells following HT treatment. Cell migration and invasion affected by HT were analyzed using Transwell migration and invasion assays. It was found that HT inhibited the proliferation of BC cells by downregulating the phosphorylation of protein kinase B. Moreover, HT effectively enhanced the sensitivity of BC cells to the chemotherapy drug cisplatin (DDP) and reduced the chemoresistance of DDP‑resistant cells by downregulating the expression of cadherin‑11. It was further demonstrated that HT inhibited the migration and invasion of BC cells and enhanced the cytotoxic effects of NK cells. In summary, the antineoplastic effects of HT were mediated through three main mechanisms: Enhancement of the chemosensitivity of BC cells and mitigation of DDP‑induced chemoresistance, suppression of the invasive potential of BC cells and reinforcement of the anticancer response of NK cells. Thus, HT appears to be a promising adjunctive therapy for human BC.

Prunella vulgaris and Tussilago farfara demonstrate anti-inflammatory activity in rabbits and protect human adipose stem cells against thermal stress in vitro

Ethnopharmacological relevancePrunella vulgaris L.(PV) and Tussilago farfara (TF) are perennial herbs rich in flavonoids and phenolic compounds with immense medicinal value. PV extract (PV-E) possesses potent antipyretic, anti-inflammtory, antioxidant, antiseptic, anti-cancer and immune stimulatory properties and have been traditionally known for the treatment of wounds, ulcers and sores. TF extract (TF-E) has been known for antibacterial, antioxidant, anti-inflammatory, anti-viral, anti-diabetic, anti-cancer, anti-obesity and wound healing effects. Additionally, TF-E infusions have been used for asthma, cough, and bronchopneumonia treatments. Aim of the studyThe therapeutic efficacy of transplanted human adipose stem cells (hASCs) is abrogated under the deteriorating effects of heat stress offered by burn wounds. Earlier researches has documented antioxidant priming as an effective strategy to enhance stem cell performance. As both PV-E and TF-E are known for their potent antioxidant effects. The present study aims to examine the cryoprotective effects of PV-E and TF-E priming on hASCs against in-vitro heat-induced thermal stress. Moreover, we determined the anti-inflammatory potential of both PV-E and TF-E on rabbits. MethodsAntioxidant capacity of both PV-E and TF-E is examined via DPPH assay and anti-inflammatory activity is assessed in rabbits using carrageen-induced paw edema model of inflammation. Next, we investigate the efficacy of different doses (1.25-100μg/ml) of PV-E and TF-E on hASCs; MTT, LDH, calcein AM staining, and wound scratch assay were used to assess cell viability, cytotoxicity, proliferation ability and cell migration potential in the cells. Then, hASCs were pretreated for 24 h with optimum doses of PV-E and TF-E determined from MTT assay results and were subsequently exposed to in-vitro thermal injury (51 °C,10 min). The cytoprotective effects of both PV-E and TF-E priming under thermal stress were investigated via MTT, LDH, annexin-V staining and gene expression analysis. ResultsBoth PV-E and TF-E extracts demonstrated potent antioxidant and effective anti-inflammatory activities, with a clear reduction in inflammation. Study on hASCs exhibited improved cell viabilities, enhanced cell proliferation and migration abilities of both extracts. While heat stress data revealed that PV-E (2.5μg/ml) and TF-E (5μg/ml) pretreatment significantly ameliorated effects of thermal-injuries in hASCs as depicted by significantly enhanced cell viabilities, low LDH release profile, and lower annexin-V expression and regulated gene expression of the pretreated cells. ConclusionPV-E and TF-E priming effectively enabled hASCs to combat thermal injury by significantly promoting cell survival than untreated cells. Hence, these findings suggest that PV-E and TF-E priming could be used to attain improved cellular responses and enhanced therapeutic efficacy in burnt tissue.

Assessment of artificial bone materials with different structural pore sizes obtained from 3D printed polycaprolactone/β-tricalcium phosphate (3D PCL/β-TCP)

Artificial bone is the alternative candidate for the bone defect treatment under the circumstance that there exits enormous challenge to remedy the bone defect caused by attributes like trauma and tumors. However, the impact of pore size discrepancy for regulating new bone generation is still ambiguous. Using direct 3D printing technology, customized 3D polycaprolactone/β-tricalcium phosphate (PCL/β-TCP) artificial bones with different structural pore sizes (1.8, 2.0, 2.3, 2.5, and 2.8 mm) were successfully prepared, abbreviated as the 3D PCL/β-TCP. 3D PCL/β-TCP exhibited a 3D porous structure morphology similar to natural bone and possessed outstanding mechanical properties. Computational fluid dynamics analysis indicated that as the structural pore size increased from 1.8 to 2.8 mm, both velocity difference (from 4.64 × 10-5to 7.23 × 10-6m s-1) and depressurization (from 7.17 × 10-2to 2.25 × 10-2Pa) decreased as the medium passed through.In vitrobiomimetic mineralization experiments confirmed that 3D PCL/β-TCP artificial bones could induce calcium-phosphate complex generation within 4 weeks. Moreover, CCK-8 and Calcein AM live cell staining experiments demonstrated that 3D PCL/β-TCP artificial bones with different structural pore sizes exhibited advantageous cell compatibility, promoting MC3T3-E1 cell proliferation and adhesion.In vivoexperiments in rats further indicated that 3D PCL/β-TCP artificial bones with different structural pore sizes promoted new bone formation, with the 2.5 mm group showing the most significant effect. In conclusion, 3D PCL/β-TCP artificial bone with different structural pore sizes could promote new bone formation and 2.5 mm group was the recommended for the bone defect repair.

Evaluating nephrotoxicity reduction in a novel polymyxin B formulation: insights from a 3D kidney-on-a-chip model.

This study aimed to assess the nephrotoxicity associated with VRP-034 (novel formulation of polymyxin B [PMB]) compared to marketed PMB in a three-dimensional (3D) kidney-on-a-chip model. To model the human kidney proximal tubule for analysis, tubular structures were established using 23 triple-channel chips seeded with RPTEC/hTERT1 cells. These cells were exposed to VRP-034 or PMB at seven concentrations (1-200 µM) over 12, 24, and 48 h. A suite of novel kidney injury biomarkers, cell health, and inflammatory markers were quantitatively assessed in the effluent. Additionally, caspase and cytochrome C levels were measured, and cell viability was evaluated using calcein AM and ethidium homodimer-1 (EthD-1). Exposure to marketed PMB resulted in significantly elevated levels (P < 0.05) of four key biomarkers (KIM-1, cystatin C, clusterin, and OPN) compared to VRP-034, particularly at clinically relevant concentrations of ≥10 µM. At 25 µM, all biomarkers demonstrated a significant increase (P < 0.05) with marketed PMB exposure compared to VRP-034. Inflammatory markers (interleukin-6 and interleukin-8) increased significantly (P < 0.05) with marketed PMB at concentrations of ≥5 µM, relative to VRP-034. VRP-034 displayed superior cell health outcomes, exhibiting lower lactate dehydrogenase release, while ATP levels remained comparable. Morphological analysis revealed that marketed PMB induced more severe damage, disrupting tubular integrity. Both treatments activated cytochrome C, caspase-3, caspase-8, caspase-9, and caspase-12 in a concentration-dependent manner; however, caspase activation was significantly reduced (P < 0.05) with VRP-034. This study demonstrates that VRP-034 significantly reduces nephrotoxicity compared to marketed PMB within a 3D microphysiological system, suggesting its potential to enable the use of full therapeutic doses of PMB with an improved safety profile, addressing the need for less nephrotoxic polymyxin antibiotics.

P22-11 An Image-based toxicity screening method: Calcein AM as an indicator of esterase activity in Daphnia magna to detect sublethal effects in vivo

P22-11 An Image-based toxicity screening method: Calcein AM as an indicator of esterase activity in Daphnia magna to detect sublethal effects in vivo

Interrogating a Compound Library in Search of an Inhibitor for TREM-like Transcript-1 to Fibrinogen Binding.

Cardiovascular disease (CVD) remains one of leading causes of death worldwide. Aberrant platelet function mediate fibrin(ogen) rich thrombi that lead to occlusive thrombi associated with mortality. The receptor, TREM-like transcript-1 (TLT-1), stored in the platelet a-granules and released upon platelet activation, binds fibrinogen and von Willebrand factor. Once it is released from platelets TLT-1 is a potential therapeutic target to prevent the thrombosis associated with CVD. Here we design an assay to screen a compound library of small molecules inhibitors. HEK-293 cells stably transfected with a full length human treml-1 construct were used to screen library of 800 compounds, for inhibition of TLT-1 to fibrinogen binding in an attachment assay using crystal violet staining. The possible cytotoxicity of the best compounds was determined via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide MTT and calcein AM staining assays. Here we demonstrate that the addition of TLT-1 to HEK-293 cells increases cell adhesion by more than 2-fold. We identified ~80 compounds that inhibit binding by more than 80%. We further tested the top compounds and confirmed that reduction of hTLT-1 to fibrinogen bound in the top compounds was not caused by cytotoxicity, as per colorimetric and fluorescent viability assays. Four compounds were identified as potential small molecule inhibitors one of which, BM-8372, demonstrated significant effect in platelet aggregation assays. Significance Statement TLT-1 is a key platelet receptor that binds fibrinogen and mediates clot formation The developed assay successfully screens 800 small molecules, pinpointing ~80 potent inhibitors that reduce TLT-1 binding by over 80%. Importantly, the study rigorously rules out cytotoxicity concerns, affirming the therapeutic potential of the identified compounds. By elucidating TLT-1's role and presenting promising inhibitors, this research offers a significant stride toward developing novel strategies to combat CVD-related thrombosis.

P-349 Impact of an Aurora kinase inhibitor on AML cells and mouse ovarian follicles in vitro

Abstract Study question Can an aurora kinase B/C inhibitor suppress AML cell line proliferation while not impacting on mouse follicles in vitro? Summary answer Exposure to an aurora kinase inhibitor at a predetermined cytotoxic concentration suppressed AML cell proliferation but had no impact on subsequent follicle health in vitro. What is known already There is a risk that cryopreserved ovarian tissue from young women with a leukaemia diagnosis harbours leukemic cells, which on grafting could transfer disease. Novel chemotherapy agents, specifically aurora kinase inhibitors [ e.g. GSK 1070916 (GSK) ], target proteins involved in chromosomal alignment and segregation during mitosis and meiosis. It is anticipated that aurora kinase inhibitors would have an impact on the development of all somatic cells, including granulosa cells proliferating during follicle growth, however a previous study using ovarian tissue pieces indicated no impact on follicles. Study design, size, duration Primary and secondary follicles (diameter ≤ 100 µm) were manually dissected from adult mouse ovaries and embedded in an extracellular scaffold together with &amp;gt;1,000 AML cells. Individual follicles and AML cells were cultured for 7 days followed by exposure to GSK for 24 hours. GSK was removed by washing and the culture continued for another two days at which time cells were assessed for normal morphology and survival with live/dead staining (Calcein AM/ Ethidium Homodimer-1). Participants/materials, setting, methods The leukemic cell line OC1-AML-3 (DSMZ) was cultured in RPMI-1640 +10% FCS and routinely passaged as recommended. Cell proliferation and cytotoxicity were assessed using the Alamar Blue assay. 20% DMSO was used as a positive control in the cytotoxicity assays and live/dead evaluation. Follicles were cultured in αMEM, ITS, FSH, ascorbic acid and 10% FCS under oil in 5%CO2 : 95% air. Survival and growth were evaluated in two extracellular scaffolds; UltiMatrix and Hystem™-HP. Main results and the role of chance Follicle survival and growth was better (p &amp;lt; 0.05) in UltiMatrix (84.7%; 61/72) compared to Hystem™-HP (72.0%;77/107) with an average increase of 20 µm in diameter at day 7. When OCI-AML-3 cells (0.7 x105/ml) were exposed to a range of concentrations of GSK (10nM to 10µM) for 24hr in an in vitro cytotoxicity assessment, survival was reduced to 0% at a concentration of 10µM. The 20% DMSO positive control also resulted in 0% survival. However, in the 3- dimensional scaffold culture, exposure to 10 µM GSK for 24hr resulted in a mean survival of OCI-AML-3 cells of 27% (100 cells counted/ well) which was similar to the 20% DMSO positive control (32%) and significantly different to the negative (no GSK) control (95%; p &amp;lt; 0.01). Follicles exposed to GSK appeared alive, emitting a strong green fluorescence for both oocyte and granulosa cells, although some of the surface follicular cells were dead. Live/dead staining of GSK exposed follicles was similar to follicles not exposed to GSK. In contrast, the majority of the follicular cells were dead following exposure to 20% DMSO. Limitations, reasons for caution Due to whole mount assessment of the follicles for live/dead staining, it is difficult to determine whether the oocyte is alive. In scaffold culture some of the free cells present may be of follicular origin, potentially resulting in overestimation of the proportion of AML cells alive after GSK treatment. Wider implications of the findings This 3- dimensional culture system, incorporating a follicle and a leukemic cell line within a scaffold provides a good model to assess the impact of chemotherapy on both cell types and could be applicable for human follicles. Trial registration number Not applicable

ATF5-Mediated Mitochondrial Unfolded Protein Response (UPRmt) Protects Neurons Against Oxygen-Glucose Deprivation and Cerebral Ischemia.

The mitochondrial unfolded protein response (UPRmt) is an evolutionarily conserved mitochondrial response that is critical for maintaining mitochondrial and energetic homeostasis under cellular stress after tissue injury and disease. Here, we ask whether UPRmt may be a potential therapeutic target for ischemic stroke. We performed the middle cerebral artery occlusion and oxygen-glucose deprivation models to mimic ischemic stroke in vivo and in vitro, respectively. Oligomycin and meclizine were used to trigger the UPRmt. We used 2,3,5-triphenyltetrazolium chloride staining, behavioral tests, and Nissl staining to evaluate cerebral injury in vivo. The Cell Counting Kit-8 assay and the Calcein AM Assay Kit were conducted to test cerebral injury in vitro. Inducing UPRmt with oligomycin protected neuronal cultures against oxygen-glucose deprivation. UPRmt could also be triggered with meclizine, and this Food and Drug Administration-approved drug also protected neurons against oxygen-glucose deprivation. Blocking UPRmt with siRNA against activating transcription factor 5 eliminated the neuroprotective effects of meclizine. In a mouse model of focal cerebral ischemia, pretreatment with meclizine was able to induce UPRmt in vivo, which reduced infarction and improved neurological outcomes. These findings suggest that the UPRmt is important in maintaining the survival of neurons facing ischemic/hypoxic stress. The UPRmt mechanism may provide a new therapeutic avenue for ischemic stroke.

Cytotoxicity and cellular uptake capacity of a berberine-loaded nanogold/collagen drug delivery system in lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. As an emerging technology, nanomedicine offers a more effective and biocompatible approach to treating lung cancer by targeting and killing uncontrolled cancer cells. This study fabricated a nanocarrier system comprising gold nanoparticles, type I collagen, and alkaline berberine (Au-Col-BB). It then thoroughly evaluated the physical and biological properties of this novel drug delivery system. The material properties were characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, dynamic light scattering, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. MTT and Calcein AM staining of A549 lung cancer cells demonstrated that treatment with Au-Col-BB significantly decreased cell viability. Annexin V/propidium iodide double staining and cell cycle progression revealed that treatment with Au-Col-BB increased apoptosis 1.82-fold in A549 cells but decreased apoptosis 0.94-cold in BEAS-2B normal lung cells. The percentage of A549 cells in the sub-G1 phase increased from 4.0 % to 11.6 % (p < 0.001), while the percentage of those in the S phase decreased from 14.5 % to 9.6 % (p < 0.010), indicating enhanced apoptosis and reduced proliferation. Treatment with Au-Col-BB significantly reduced the migration distance of A549 cells by 51 %. Au-Col-BB was found to primarily enter cells via clathrin-mediated endocytosis and autophagy, which were inhibited by chlorpromazine and bafilomycin A1, respectively. Retroorbital sinus injection of Au-Col-BB into BALB/c mice demonstrated its integrity and safety in vivo. Overall, this study suggests that the Au-Col-BB nanocarrier system is a promising alternative for antineoplastic drugs, offering effective cancer cell targeting and apoptosis induction while minimizing damage to surrounding healthy tissues.

Tongue depressor (bio)sensors: A fast decentralized self-testing of salivary biomarkers for personalized medicine

The clinical tests usually make use of blood samples, requiring invasive sample collection protocols, which are not appropriate for decentralized, frequent, and point-of-care (POC) applications. Here, we report disposable (bio)sensors combining electrochemical and colorimetric technologies on an accessible and lightweight wooden tongue depressor platform. The array of (bio)sensors on this commonly used medical tool enables rapid, and safe saliva sampling and showed promise to be used for frequent self-testing of four clinically relevant biomarkers (glucose, uric acid, nitrite, and thiocyanate) in saliva. The electrochemical system was designed to detect uric acid and glucose by chronoamperometric measurements in clinically relevant concentrations ranging from 50 to 500 µmol L−1 and from 10 to 5000 µmol L−1, respectively. Meanwhile, the colorimetric paper-based spot tests were optimized to detect nitrite and thiocyanate in concentrations ranging from 5 to 200 µmol L−1 and 0.5 to 2.1 mmol L−1, respectively, using digital image colorimetry. Our affordable tongue depressor (bio)sensors provide results within 5 min and achieve limits of detection in the µmol L−1 range. Importantly, the results provided by our tests when applied to human saliva samples presented excellent concordance with the traditional spectrophotometric method (at a 95 % confidence level), demonstrating the reliability and robustness of our method. In addition, the toxicity and biocompatibility studies of the tongue depressor (bio)sensors were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Calcein acetoxymethyl ester (Calcein AM), and Calcein Propidium Iodide Hoechst (Calcein PI) Analysis, confirming the safety use of the test. Therefore, our tongue depressor (bio)sensor facilitates frequent testing of several biomarkers and can contribute to personalized medicine.

Simultaneous isolation of intact brain cells and cell-specific extracellular vesicles from cryopreserved Alzheimer’s disease cortex

BackgroundThe neuronal and gliaI populations within the brain are tightly interwoven, making isolation and study of large populations of a single cell type from brain tissue a major technical challenge. Concurrently, cell-type specific extracellular vesicles (EVs) hold enormous diagnostic and therapeutic potential in neurodegenerative disorders including Alzheimer’s disease (AD). New MethodPostmortem AD cortical samples were thawed and gently dissociated. Following filtration, myelin and red blood cell removal, cell pellets were immunolabeled with fluorescent antibodies and analyzed by flow cytometry. The cell pellet supernatant was applied to a triple sucrose cushion for brain EV isolation. ResultsNeuronal, astrocyte and microglial cell populations were identified. Cell integrity was demonstrated using calcein AM, which is retained by cells with esterase activity and an intact membrane. For some experiments cell pellets were fixed, permeabilized, and immunolabeled for cell-specific markers. Characterization of brain small EV fractions showed the expected size, depletion of EV negative markers, and enrichment in positive and cell-type specific markers. Comparison with existing methods and conclusionsWe optimized and integrated established protocols, aiming to maximize information obtained from each human autopsy brain sample. The uniqueness of our method lies in its capability to isolate cells and EVs from a single cryopreserved brain sample. Our results not only demonstrate the feasibility of isolating specific brain cell subpopulations for RNA-seq but also validate these subpopulations at the protein level. The accelerated study of EVs from human samples is crucial for a better understanding of their contribution to neuron/glial crosstalk and disease progression.

In vitro cell killing proficiency of autologous immune cells educated with allogenic multi-cancer tumor cell lysate.

e14675 Background: Allogenic tumor lysate therapies offer a novel approach in oncology, to initiate a measured immune system response to combat cancer. Loaded with tumor antigens, these lysates stimulate the patient's immune system for targeted cancer cell destruction. In vitro data suggesting efficacy is pivotal prior to clinical trials. Per-C-Vax is a novel, organ-agnostic, allogenic tumor lysate immuno-stimulant, and is intended to target solid organ malignancies via subcutaneous injection. It is derived from a multi-organ cell-line cocktail, which has been induced into apoptosis to capture diverse Tumor Associated Molecular Patterns (TAMPs) and Damage Associated Molecular Patterns (DAMPs). Our study assesses Per-C-Vax-educated patient-specific immunocytes' in-vitro cell-killing activity against their autologous tumor cells. Methods: We collected simultaneous blood and tumor tissue samples from 22 patients with solid organ tumors under approved protocols. The cohort included 10 head and neck (45%), 4 breast (18%), and 8 other cancers (36%) comprising colorectal, ovary, lung, gallbladder, prostate, uterine, cervix, and gastric cancers. Peripheral Blood Mononuclear Cells (PBMCs) from a 10 ml venous draw were split into control and Per-C-Vax incubated aliquots for each patient. Approximately 1,000 tumor cells, stained with Calcein AM, were co-cultured with about 20,000 cells from each of the Per-C-Vax and control PBMC aliquots (autologous). Imaging-based pre- and post-co-culture counts determined the cell-kill rate for each aliquot. Results: PBMCs not treated with Per C Vax showed a significantly reduced cancer cell killing activity against autologous tumor cells compared to Per-C-Vax -treated PBMCs, suggesting the tolerogenic characteristic of immunocytes to the malignancy (0%-32%, 95% CI 10.16 to 16.65). On the other hand, PBMCs treated with Per-C-Vax showed significant cell-kill activity ranging from 46% to 84% in head and neck (mean 62.1%, 95% CI 52.67 to 71.53), 51% to 73% in breast (mean 62%, 95% CI 44.33 to 79.67), 38% to 87% in other cancers (colorectal, ovary, lung, gallbladder, prostate, uterine, cervix, gastric) (mean 50.87%, 95% CI 37.71 to 64.04). A comparative analysis between the untreated group and the group treated with Per-C-Vax revealed a statistically significant result with a p-value &lt;0.005. Conclusions: Patient-specific PBMCs incubated with Per-C-Vax tumor lysate immuno-stimulant show significant autologous cancer cell killing activity against multiple cancers in vitro. Human trials to establish safety and efficacy are planned.

HiPSC-derived cardiomyocyte cultivation and measurement of electrophysiological properties on gelatine/glucose/polypyrrole scaffold

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): EU Horizon 2020 Framework Programme (H2020) under Grant agreements No. 953138 (EMAPS-Cardio) Purpose Cardiotoxicity is one of the main side effects limiting development of new medicines and resulting in withdrawal of drugs from the market. There are different mechanisms of drug-induced cardiotoxicity, including arrhythmia, disruption of mitochondria function, apoptosis, altered growth factor signalling [1]. Heart on a chip model for drug testing seems attractive approach to evaluate the possible cardiotoxic effects on cell biological, but mostly electrophysiological properties. Our aim was to create a 3D system with a biocompatible scaffold, coated with a conductive layer, suitable for culturing and maturation of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) and compatible with electrophysiology parameter measurement techniques. Methods Elastic scaffold was fabricated by electrospinning of gelatin-glucose microfibers followed by the vapor-phase and electrochemical deposition of conductive polymer polypyrrole (PPy) to create electroconductive layer. hiPSC-CMs at different maturation levels (at 6 vs 14 weeks) were used to test biocompatibility of the scaffold. To increase cell attachment, scaffold was treated with 0.1 M HCl and coated with Geltrex. Cells were stained with fluorescent dyes (Calcein AM, DAPI). Electrophysiological properties were analysed using intracellular calcium imaging (Cal520) and action potential recordings with sharp electrodes. HiPSC-CMs on coverslips were used as a 2D control. Results Calcein AM staining showed that high number of hiPSC-CMs attached to gelatine/glucose/PPy scaffold proving that the scaffold is biocompatible and cells remain viable even after long term incubation (&amp;gt; 2 weeks). HiPSC-CMs at lower maturity (6 weeks) had better attachment properties to it, indicating that more mature cardiomyocytes (14 weeks) gradually lose their capacity to attach to PPy surface. Intracellular calcium imaging showed that both types of cells generated synchronous spontaneous calcium oscillations on gelatine/glucose/PPy scaffolds. Action potential recordings in 3D were similar to those in 2D, and confirmed differences in hiPSC-CMs maturation levels – at lower maturation level hiPSC-CMs had lower upstroke velocity as compared to more matured hiPSC-CMs. Conclusions Gelatine/glucose/PPy scaffold is biocompatible for hiPSC-CMs cultivation, and suitable for evaluation of cardiomyocyte electrophysiological properties. Such electromechanoactive scaffold can be further employed for development of heart-on-a-chip model.

Viability and Proliferation Assessment of Gingival Fibroblasts Cultured on Silver Nanoparticle-Doped Ti-6Al-4V Surfaces.

To investigate the biocompatibility of silver nanoparticle (AgNP)-doped Ti-6Al-4V surfaces by evaluating the viability and proliferation rate of human gingival fibroblasts (HGFs)-as the dominant cells of peri-implant soft tissues-seeded on the modified surfaces. AgNPs (sizes 8 nm and 30 nm) were incorporated onto Ti-6Al-4V specimen surfaces via electrochemical deposition, using colloid silver dispersions with increasing AgNP concentrations of 100 ppm, 200 ppm, and 300 ppm. One control and six experimental groups were included in the study: (1) control (Ti-6Al-4V), (2) 8 nm/100 ppm, (3) 8 nm/200 ppm, (4) 8 nm/300 ppm, (5) 30 nm/100 ppm, (6) 30 nm/200 ppm, and (7) 30 nm/300 ppm. HGF cell primary cultures were isolated from periodontally healthy donor patients and cultured in direct contact with the group specimens for 24 and 72 hours. The cytotoxicity of AgNP-doped Ti-6Al-4V specimens toward HGF was assessed by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) and BrdU (5-bromo-2'-deoxyuridine) assay tests. Calcein AM and ethidium homodimer (EthD-1) fluorescent stains were used to determine the live and dead cells. The morphology and attachment properties of the HGFs were determined via scanning electron microscopy (SEM). Energy dispersive x-ray (EDX) analysis confirmed the presence of AgNPs on the specimens. The MTT test revealed that AgNPs of both sizes and all concentrations presented a decreased cellular metabolic activity compared to the control discs. All concentrations of both sizes of AgNPs affected the cell proliferation rate compared to the control group, as revealed by the BrdU assay. Overall, cytotoxicity of the modified Ti-6Al-4V surfaces depended on cell exposure time. Observation via confocal microscopy confirmed the results of the MTT and BrdU assay tests. Specifically, most cells remained alive throughout the 72-hour culture period. SEM images revealed that adjacent cells form bonds with each other, creating confluent layers of conjugated cells. The findings of the present study indicate that Ti-6Al-4V surfaces modified with 8 nm and 30 nm AgNPs at concentrations of 100 ppm, 200 ppm, and 300 ppm do not produce any serious cytotoxicity toward HGFs. The initial arrest of the HGF proliferation rate recovered at 72 hours. These results on the antibacterial activity against common periodontal pathogens, in combination with the results found in a previous study by the same research group, suggest that AgNP-doped Ti-6Al-4V surfaces are potential candidates for use in implant abutments for preventing peri-implant diseases.

Abstract 3102: A high-throughput screening method for discovering potent P-glycoprotein modulators from the chemical library in Tohoku University

Abstract Background: Drug development is important for cancer therapy to improve patient outcomes. In most cases, drug development starts in discovering candidate compounds from a chemical library in high-throughput screening (HTS). Tohoku University Graduate School of Pharmaceutical Science owns the original chemical library consisting of thousands of original chemical compounds. P-glycoprotein (P-gp), a major drug efflux transporter mediates multi-drug resistance (MDR) in cancer cells. Therefore, P-gp modulators could revere MDR and increase chemosensitivity. The aim of this study is to reveal an adequate method of HTS for discovering potent P-gp modulators from the chemical library in Tohoku University. Methods: The chemical library in Tohoku University had 5861 compounds in the present study, and the collection contains over 7 thousand compounds in 2023. P-gp overexpressing KB-V1, human epidermal carcinoma cell lines were obtained, and calcein AM, P-gp substrate was employed for fluorescent substrate efflux assays. A plate reader-based calcein AM efflux assay for HTS was established to select candidate compounds as P-gp modulators. After the primary HTS, structures of the candidate compounds were analyzed, then several analogous compounds were extracted from the chemical library. For the validation of the hit compounds in HTS and the analogs, a flow cytometry-based calcein AM efflux assay was conducted. In addition, reversal effects of P-gp modulators on the cytotoxicity of paclitaxel were measured in a cell proliferation assay. Results: Of 5861 compounds in the chemical library, 53 compounds showed 2-fold or higher fluorescence intensity, and then 13 compounds showed 3-fold or higher fluorescence intensity in a plate reader-based assay for the HTS. Especially 2 candidate compounds showed over 5-fold fluorescence intensity. In the analysis for structures of the candidate compounds, 20 analogous compounds were extracted from the chemical library. To verify the result of the plate reader-based assay, a flow cytometry-based assay was conducted for 53 hits and 20 analogs. As a result, the 2 candidate compounds that selected in the plate reader-based assay showed 60-fold, the highest fluorescence intensity in a flow cytometry-based assay. The other compounds showed less fluorescence intensity than these 2 candidates. In addition, both candidates enhanced the paclitaxel-induced cytotoxicity in a cell proliferation assay. Conclusions: A plate reader-based calcein AM efflux assay in HTS was an adequate method for discovering potent P-gp modulators from the chemical library in Tohoku University. Citation Format: Norihiko Sugisawa, Shinobu Ohnuma, Takayuki Doi, Michiaki Unno. A high-throughput screening method for discovering potent P-glycoprotein modulators from the chemical library in Tohoku University [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3102.

Abstract 4919: AI-enabled hit selection of drug screening on human pancreatic cancer organoids

Abstract Cancer remains one of the leading causes of death in the 21st century. Despite the latest advances in oncology, most cancer patients lack tailored therapeutic approaches with lasting benefit. Measuring the impact of anticancer compounds and their combinations is only possible on ex vivo assays. To this end, patient-derived organoids (PDOs) have been proposed as viable and efficient models for ex vivo testing. PDOs show long-term expansion potential while retaining tumor histopathology as well as cancer gene mutations. However, the translation of organoids in screening applications has so far been hampered by the lack of homogeneity and difficulties in handling and automation. Moreover, organoids are typically randomly distributed across the culture which complicates imaging and images analyses. To overcome these challenges, we set up a compound screening workflow with PDOs using Gri3D platform, comprising plates with micro-cavities suitable for high-throughput and reproducible organoid culture. Based on a standard 96 microtiter plate, each well contains a microwell array patterned in a cell repellent hydrogel. On Gri3D®, organoids are robustly generated in the microwells and are located in the same imaging plane. This greatly facilitates quantitative analyses in high content image-based screens. Furthermore, the pipetting port enables automation of cell seeding, media exchange and compound incubation with liquid-handlers, thus increasing assay reproducibility. In the presented work, we exposed human pancreatic cancer PDOs to a panel of anti-cancer compounds at different doses and followed their response to the drugs using viability dyes Calcein AM (live stain) and Ethidium Homodimer-1 (dead stain) with high-content confocal imaging. Using an AI-based approach, we efficiently detected each single organoid and extracted phenotypic features from all three channels (TL, live stain and dead stain) which correlate with cytotoxicity. The extracted features (more than 100) were first dimensionally reduced to 3 components using either PCA or UMAP, the treatments were then visualized in 3D scatter plots, ranked and clustered using machine learning. The data suggests that the compound treatment Palbociclib 50uM has significant cytotoxicity effects similar to the positive control, which is consistent with the traditional live/dead analysis. The AI approach demonstrates feasibility to perform drug screening in a robust and un-biased data analysis approach. Citation Format: Zhisong Tong, Angeline Lim, Marine Meyer, Maria Clapes, Oksana Sirenko, Nathalie Brandenberg. AI-enabled hit selection of drug screening on human pancreatic cancer organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4919.

Abstract 2060: Automation of 3D cancer spheroid assay for compound screening

Abstract Finding efficient drug combinations to treat cancer patients is critical for therapy success. Accordingly, there is a critical need to develop methods for efficient testing drug efficacy to discover new therapeutic targets. 3D cancer models are highly valuable tools for cancer research and drug development. However, the complexity of performing 3D assays remains a hurdle for adopting these methods for compound screening. To alleviate the bottlenecks that come with labor-intensive manual protocols we developed cell culture automation methods using CellXpress.ai instrument. The instrument enables automation of 2D or 3D culture for prolonged complex workflows. The CellXpress.ai provides automated plating, passaging, media exchanges, monitoring organoids, alone with compound treatment and the end point assays with high content image analysis. In the present study we describe full automation of imaging, analysis, and cell culture process which enables scaling up complex 3D cell-based assays and compound screening. As an example of 3D protocol, we automated culture and imaging of colorectal cancer 3D spheroids formed from HCT116 cell line in U-shape low attachment plates. HCT116 cells were expanded in 2D, then spheroids were formed after automated dispensing of cell suspension into U-shape 96 or 384 plates. After 48h spheroids were treated with 12 anti-cancer compounds, at multiple concentrations for 3-5 days, then stained and imaged. Cell plating, compound additions, media exchange, and staining were performed automatically by CellXpressAI instrument. During the culture spheroids were monitored using transmitted light, with immediate analysis of phenotypic changes, including inhibition of growth or spheroid disintegration. For endpoint assay spheroids were stained with combination of Hoechst nuclear stain and viability dyes Calcein AM and EtHD, then imaged, and analyzed for multiple read-outs including spheroid size, marker intensities, and live-dead cell scoring. We observed concentration-dependent inhibition of spheroid growth and cell death in response to anti-cancer compounds and evaluated effective compound concentrations for cytotoxic or cytostatic effects. Cell culture process automation for 3D assays, powered by imaging and image analysis has a potential to bring 3D biology into another level, allowing to increase throughput and reproducibility, and enabling variety of high throughput drug discovery and precision medicine applications. Citation Format: Oksana Sirenko, Angeline Lim, Astrid Michlmayr, Zhisong Tong, Emilie Keidel, Felix Spira. Automation of 3D cancer spheroid assay for compound screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2060.

Abstract 4750: The MNK inhibitor EB1 sensitizes AR-V7 positive castration-resistant prostate cancer to enzalutamide

Abstract Introduction: Resistance to androgen receptor signaling inhibitors (ARSI) like Enzalutamide is frequent in castration resistant prostate cancer (CRPC). The mechanisms driving drug resistance include the overexpression of androgen receptor (AR) and the presence of splice variants like androgen receptor splice variant 7 (AR-V7). Clinical studies (PROPHECY) have demonstrated that AR-V7 positive CRPC patients treated with Enzalutamide show poorer overall survival and thus lack an effective targeted line of treatment. Recently, AR signaling and the regulation of protein translation via the translation initiation factor 4E (eIF4E) and MAPK-interacting kinases (MNKs) have been shown to depend on each other and targeting eIF4E has been proposed to increase the efficacy of ARSI. Objectives: We have recently described EB1 as the first in class non-ATP competitive inhibitor of MNK1/2 (Bou-Petit et al. JMC, 2022) and have now tested its applicability in CRPC. In this work we describe the impact of EB1 on the efficacy of Enzalutamide treatment in CRPC. Methodology: Cell lines 22RV1 and LNCaP-95 were used as AR-V7 positive models of CRPC. Effects of EB1 and Enzalutamide alone and in combination on cell growth were studied through crystal violet assay. Drug combination Index was calculated following Chou-Talalay method using CompuSyn Software. Cell death was studied through propidium iodide (PI) staining. AR transcriptional activity was assessed through RT-qPCR of AR canonical target genes like PSA. A head-to-head study with eFT-508 (Tomivosertib, eFFECTOR Therapeutics, Inc.) as the most advanced Type I MNK inhibitor was performed. Lastly, spheroids obtained through centrifugation in ultra-low attachment plates were used for validating drug interaction in 3D growth and viability studies. Spheroid viability was assessed through PI and Calcein AM staining as well as MTT assay. Results: In vitro results demonstrate strong to moderate synergistic inhibition of cell growth through the induction of cell death by the combination of Enzalutamide and EB1 in AR-V7 positive CRPC cell lines, as well as reduction of AR transcriptional activity (PSA). Drug combination also reduced growth and viability of spheroids, indicating good tumor penetrating properties in 3D models and giving in vitro proof-of-concept for in vivo applications. Furthermore, drug synergy with Enzalutamide could only be observed with EB1 and not with Type-I MNK inhibitors like eFT-508, indicating that MNK1/2 functions beyond its kinase activity might be relevant for cancer progression. Conclusion: Here we demonstrate that the novel MNK inhibitor EB1 shows promising in vitro results, which cannot be obtained with Type-I MNK inhibitors. The combination of EB1 with the standard of care Enzalutamide provide a novel therapeutic opportunity for the treatment of CRPC, particularly in AR-V7 positive patients. Citation Format: Sara García-Ortega, Leticia Suárez-Cabrera, Joan Morote, Olga Méndez, Marta Cano-Galietero, Elena Muro-Blanc, Jose I. Borrell, Anna Santamaria, Santiago Ramón y Cajal, Stefan Hümmer. The MNK inhibitor EB1 sensitizes AR-V7 positive castration-resistant prostate cancer to enzalutamide [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4750.

Abstract 4774: Inhibition of pancreatic acinar ductal metaplasia by novel YAP/TAZ inhibitor, CV-4-26

Abstract Current challenges for pancreatic ductal adenocarcinoma (PDAC) treatment include overcoming the disease’s fibrous tumor microenvironment with limited cytotoxicity- in which tissue stiffening is believed to occur even pre-disease onset. Acinar to ductal metaplasia (ADM), the transdifferentiation of acinar cells into duct-like cells, is a predisposing event to PDAC development that is also linked to Hippo signaling, a major pathway involved in fibrosis and inflammation. Hippo activation is initiated by the yes-associated protein (YAP) in conjunction with the PDAZ binding motif (TAZ) and TEA domain (TEAD) transcription factor. Thus, the synthesis of the novel covalent TEAD autopalmitoylation inhibitor, CV-4-26, presented an opportunity to therapeutically target ADM. CV-4-26 binds to the TEAD lipid binding pocket, which, in turns, hinders TEAD palmitoylation, thereby leading to the inhibition of the Hippo pathway. Utilizing our 3D organoid p48Cre/+LSL-KRASG12D/+ (KC) mouse model, we demonstrated pronounced phenotypic and molecular inhibition of ADM by CV-4-26, resulting in a conserved acinar phenotype, as well as downregulation of downstream markers of the YAP/TAZ complex. The compound did not reverse ADM to the acinar state once ducts were visibly formed. Yet, CV-4-26 demonstrated a lack of cytotoxicity (up to 25 µM) as determined by Calcein AM staining. Biomechanical measurements of extracellular matrix stiffness acquired through calculations of fluorescent nanoparticle displacement further displayed decreased moduli as a response to inhibition treatment. Moreover, a 56-fold downregulation of collagen (COL1A1, COL1A2) mRNA, markers for PDAC development, was observed. However, less reduction in the collagens and extracellular matrix stiffness was observed in the ADM reversal treatments, corroborating our morphology and gene expression results. Our data suggest that combining CV-4-26 by ADM inhibition with standard of care therapies for PDAC may enhance the penetration of small molecules through the tumor’s extracellular matrix. Citation Format: Corey M. Perkins, Chen Zhou, Martha Campbell-Thompson, Yating Mao, Kalina R. Atanasova, Jinmai Jiang, Ranjala Ratnayake, Hendrik Luesch, Jamel Ali, Chenglong Li, Thomas D. Schmittgen. Inhibition of pancreatic acinar ductal metaplasia by novel YAP/TAZ inhibitor, CV-4-26 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4774.