Focused Ultrasound Treatment of a Spheroid In Vitro Tumour Model

Real-time monitoring and quantitative analysis of 3D tumor spheroids using portable cellular imaging system

Three-dimensional (3D) tumor spheroid models closely mimic in vivo tumor environment and play a vital role in studying oncological research. Despite their significance, the existing methods for analyzing 3D tumor spheroids often suffer from limitations, including low throughput, high cost, and insufficient resolution. To address these challenges, we developed a portable imaging system for the real-time sensing and quantitative analysis of the 3D tumor spheroids. The system integrated the seamless workflow of spheroid generation, cell morphology tracking, and drug screening. The spheroid generation was successfully characterized using MCF-7 breast cancer cells by optimizing cell concentration (5-20 × 106 cells/mL), incubation time (24-96 h) and microwell diameter (400-600 μm). A custom-written algorithm was developed for automated analysis of spheroids, exhibiting high sensitivity (98.99%) and specificity (98.21%). Confusion matrices and receiver operating characteristic curve analysis further confirmed the robustness of the algorithm with an area under the curve value of 93.75% and an equal error rate of 0.79%. Following the characterization, the real-time sensing of spheroid generation and the response of spheroids to drug treatment were successfully demonstrated. Furthermore, the live/dead assays with chemotherapy provided a detailed insight into the efficacy and cytotoxic effects of the drug, demonstrating a significant dose-dependent decrease in a spheroid viability. Therefore, our system offers considerable potential for enhancing drug development processes and personalized treatment strategies, thereby contributing to more effective cancer therapies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-025-00470-y.

Possible Association of Nrf2/ARE and NFκB Response to Osteoblast Function in Spheroid Culture Induced by Low-Intensity Pulsed Ultrasound (LIPUS)

OBJECTIVE

NFκB negatively affects bone metabolism through inflammatory pathways, whereas Nrf2 benefits it by regulating antioxidant/detoxifying enzymes through antioxidant response element (ARE) activity. We investigated whether low-intensity pulsed ultrasound (LIPUS) enhances osteogenic differentiation in 3D culture and whether it affects osteoblastic differentiation-associated markers such as calcium and alkaline phosphatase (ALP), and the regulation of NFκB and/or ARE.

METHODS

Murine MC3T3-E1 preosteoblasts were used to produce 3D-spheroids, which were treated with LIPUS. Time-dependent morphological change of spheroids was evaluated by microscopy, histology, and micro-CT. To analyze changes in ARE levels, a combination of LIPUS with an optimal concentration and timing of the Nrf2-inducer sulforaphane was applied. Osteoblast differentiation and mineralization were achieved through stimulation with differentiation medium for 21-28 days, during which LIPUS was used every day at 24-hour intervals. Differentiation was evaluated using calcium and ALP assay. Finally, cells were transduced with SIN-lenti-NFκB/SIN-lenti-ARE construct, and the effects of single-shot LIPUS on NFκB and ARE were evaluated using Nano-Glo® Luciferase Assay.

RESULTS

Morphologically, in LIPUS group, shrinkage behaviour, which may correlate with cell differentiation, was observed to be more pronounced. NFκB activity with LIPUS was significantly lower than without treatment, whereas ARE activity showed significant increase only immediately after LIPUS treatment. Conversely, LIPUS enhanced ARE activity in combination with sulforaphane administration. After 28 days, the calcium content and ALP activity of LIPUS-treated spheroids increased significantly.

CONCLUSION

This study suggests that LIPUS may have NFκB-downregulating, limited ARE-raising effects in combination with sulforaphane, and elevating osteoblast mineralization three-dimensionally. Thus, LIPUS could be useful for treating fractures in conditions of oxidative stress and hyper-inflammation.

Cell-Based Glioma Models for Anticancer Drug Screening: From Conventional Adherent Cell Cultures to Tumor-Specific Three-Dimensional Constructs

Gliomas are a group of primary brain tumors characterized by their aggressive nature and resistance to treatment. Infiltration of surrounding normal tissues limits surgical approaches, wide inter- and intratumor heterogeneity hinders the development of universal therapeutics, and the presence of the blood-brain barrier reduces the efficiency of their delivery. As a result, patients diagnosed with gliomas often face a poor prognosis and low survival rates. The spectrum of anti-glioma drugs used in clinical practice is quite narrow. Alkylating agents are often used as first-line therapy, but their effectiveness varies depending on the molecular subtypes of gliomas. This highlights the need for new, more effective therapeutic approaches. Standard drug-screening methods involve the use of two-dimensional cell cultures. However, these models cannot fully replicate the conditions present in real tumors, making it difficult to extrapolate the results to humans. We describe the advantages and disadvantages of existing glioma cell-based models designed to improve the situation and build future prospects to make drug discovery comprehensive and more effective for each patient according to personalized therapy paradigms.

Experimental and Computational Analysis of High-Intensity Focused Ultrasound Thermal Ablation in Breast Cancer Cells: Monolayers vs. Spheroids

High-intensity focused ultrasound (HIFU) is a non-invasive therapeutic modality that uses precise acoustic energy to ablate cancerous tissues through coagulative necrosis. In this context, we investigate the efficacy of HIFU ablation in two distinct cellular configurations, namely 2D monolayers and 3D spheroids of epithelial breast cancer cell lines (MDA-MB 231 and MCF7). The primary objective is to compare the response of these two in vitro models to HIFU while measuring their ablation percentages and temperature elevation levels. HIFU was systematically applied to the cell cultures, varying ultrasound intensity and duty cycle during different sonication sessions. The results indicate that the degree of ablation is highly influenced by the duty cycle, with higher duty cycles resulting in greater ablation percentages, while sonication duration has a minimal impact. Numerical simulations validate experimental observations, highlighting a significant disparity in the response of 2D monolayers and 3D spheroids to HIFU treatment. Specifically, tumor spheroids require lower temperature elevations for effective ablation, and their ablation percentage significantly increases with elevated duty cycles. This study contributes to a comprehensive understanding of acoustic energy conversion within the biological system during HIFU treatment for 2D versus 3D ablation targets, holding potential implications for refining and personalizing breast cancer therapeutic strategies.

Holographic Focused Ultrasound Hyperthermia System for Uniform Simultaneous Thermal Exposure of Multiple Tumor Spheroids

Hyperthermia is currently used to treat cancer due to its ability to radio- and chemo-sensitize and to stimulate the immune response. While ultrasound is non-ionizing and can induce hyperthermia deep within the body non-invasively, achieving uniform and volumetric hyperthermia is challenging. This work presents a novel focused ultrasound hyperthermia system based on 3D-printed acoustic holograms combined with a high-intensity focused ultrasound (HIFU) transducer to produce a uniform iso-thermal dose in multiple targets. The system is designed with the aim of treating several 3D cell aggregates contained in an International Electrotechnical Commission (IEC) tissue-mimicking phantom with multiple wells, each holding a single tumor spheroid, with real-time temperature and thermal dose monitoring. System performance was validated using acoustic and thermal methods, ultimately yielding thermal doses in three wells that differed by less than 4%. The system was tested in vitro for delivery of thermal doses of 0-120 cumulative equivalent minutes at 43 °C (CEM43) to spheroids of U87-MG glioma cells. The effects of ultrasound-induced heating on the growth of these spheroids were compared with heating using a polymerase chain reaction (PCR) thermocycler. Results showed that exposing U87-MG spheroids to an ultrasound-induced thermal dose of 120 CEM43 shrank them by 15% and decreased their growth and metabolic activity more than seen in those exposed to a thermocycler-induced heating. This low-cost approach of modifying a HIFU transducer to deliver ultrasound hyperthermia opens new avenues for accurately controlling thermal dose delivery to complex therapeutic targets using tailored acoustic holograms. Spheroid data show that thermal and non-thermal mechanisms are implicated in the response of cancer cells to non-ablative ultrasound heating.

Let’s Go 3D! New Generation of Models for Evaluating Drug Response and Resistance in Prostate Cancer

Prostate cancer (PC) is the third most frequently diagnosed cancer worldwide and the second most frequent in men. Several risk factors can contribute to the development of PC, and those include age, family history, and specific genetic mutations. So far, drug testing in PC, as well as in cancer research in general, has been performed on 2D cell cultures. This is mainly because of the vast benefits these models provide, including simplicity and cost effectiveness. However, it is now known that these models are exposed to much higher stiffness; lose physiological extracellular matrix on artificial plastic surfaces; and show changes in differentiation, polarization, and cell–cell communication. This leads to the loss of crucial cellular signaling pathways and changes in cell responses to stimuli when compared to in vivo conditions. Here, we emphasize the importance of a diverse collection of 3D PC models and their benefits over 2D models in drug discovery and screening from the studies done so far, outlining their benefits and limitations. We highlight the differences between the diverse types of 3D models, with the focus on tumor–stroma interactions, cell populations, and extracellular matrix composition, and we summarize various standard and novel therapies tested on 3D models of PC for the purpose of raising awareness of the possibilities for a personalized approach in PC therapy.