Exploiting Shock Waves to Trigger the Anticancer Sonodynamic Activity of 5-Aminolevulinc Acid-Derived Protoporphyrin IX on In Vitro 2D and 3D Cancer Models

Enhancing Sonodynamic Therapy in Prostate Cancer: Cavitation-Induced Cytotoxicity and Mitochondrial Unfolded Protein Response Disruption

Prostate cancer remains a significant health challenge, necessitating more effective and targeted treatment strategies. Sonodynamic therapy (SDT) is a promising, non-invasive approach that utilizes ultrasound-activated sensitizers to induce cancer cell death. However, the role of ultrasound cavitation in enhancing SDT efficacy and its effects on mitochondrial stress responses remain unclear. We hypothesized that increasing cavitation density through optimized ultrasound parameters would enhance Ce6-mediated SDT effectiveness by increasing cytotoxicity, reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) loss, and disrupting the mitochondrial unfolded protein response (mtUPR). Prostate cancer cells were treated with Ce6 and exposed to ultrasound with varying duty cycles (50% and 100%) and power intensities (0.5 W/cm2, 1 W/cm2, and 1.5 W/cm2). Cavitation density was measured, and its effects on cell viability, ROS levels, MMP disruption, and mtUPR mediator expression, including activating transcription factor 5 (ATF5), heat shock protein 60 (HSP60), and caseinolytic protease proteolytic subunit (CLPP), were analyzed at protein and mRNA levels. Higher duty cycles significantly increased cavitation density, leading to enhanced cytotoxicity, elevated ROS generation, and greater MMP loss in Ce6-mediated SDT. Additionally, SDT reduced mtUPR mediator expression, with cavitation further amplifying these effects. These findings suggest that cavitation-enhanced SDT may contribute to improved therapeutic efficacy in prostate cancer treatment by modulating mitochondrial stress responses and affecting cell viability. Optimizing ultrasound parameters to maximize cavitation effects may contribute to the development of more effective SDT-based cancer therapies.

Integrating coaxial electrospinning and 3D printing technologies for the development of biphasic porous scaffolds enabling spatiotemporal control in tumor ablation and osteochondral regeneration

The osteochondral defects (OCDs) resulting from the treatment of giant cell tumors of bone (GCTB) often present two challenges for clinicians: tumor residue leading to local recurrence and non-healing of OCDs. Therefore, this study focuses on developing a double-layer PGPC-PGPH scaffold using shell-core structure nanofibers to achieve "spatiotemporal control" for treating OCDs caused by GCTB. It addresses two key challenges: eliminating tumor residue after local excision and stimulating osteochondral regeneration in non-healing OCD cases. With a shell layer of protoporphyrin IX (PpIX)/gelatin (GT) and inner cores containing chondroitin sulfate (CS)/poly(lactic-co-glycolic acid) (PLGA) or hydroxyapatite (HA)/PLGA, coaxial electrospinning technology was used to create shell-core structured PpIX/GT-CS/PLGA and PpIX/GT-HA/PLGA nanofibers. These nanofibers were shattered into nano-scaled short fibers, and then combined with polyethylene oxide and hyaluronan to formulate distinct 3D printing inks. The upper layer consists of PpIX/GT-CS/PLGA ink, and the lower layer is made from PpIX/GT-HA/PLGA ink, allowing for the creation of a double-layer PGPC-PGPH scaffold using 3D printing technique. After GCTB lesion removal, the PGPC-PGPH scaffold is surgically implanted into the OCDs. The sonosensitizer PpIX in the shell layer undergoes sonodynamic therapy to selectively damage GCTB tissue, effectively eradicating residual tumors. Subsequently, the thermal effect of sonodynamic therapy accelerates the shell degradation and release of CS and HA within the core layer, promoting stem cell differentiation into cartilage and bone tissues at the OCD site in the correct anatomical position. This innovative scaffold provides temporal control for anti-tumor treatment followed by tissue repair and spatial control for precise osteochondral regeneration.

Effective Combination of Targeted Therapies with Sonodynamic Treatment for Use in Exploring Differences in Therapeutic Efficacy across Organelle Targets

Acoustic kinetic therapy systems that target specific organelles can improve the precision of a sonosensitizer, which is a perfect combination of targeted therapy and sonodynamic therapy (SDT) and plays an important role in current acoustic kinetic therapy. In this study, we loaded PpIX, a sonosensitizer, on targeted-functional carbon dots (CDs) via an amide reaction and then generated the mitochondria-targeted system (Mit-CDs-PpIX) and nucleus-targeted system (Nuc-CDs-PpIX), respectively, to deliver the sonosensitizer. Both systems exhibited minimal cytotoxicity in the absence of ultrasound stimulation. The efficacy of the targeted SDT systems was investigated using methylthiazol tetrazolium (MTT) assays, live/dead staining, flow cytometry, etc. Compared with the free PpIX and mitochondria-targeted system, the nucleus-targeted system is more potent in killing effect under ultrasound stimulation and induces apoptosis with higher intensity. To achieve the equal killing effect, the effective concentration of Nuc-CDs-PpIX is just one third of that of Mit-CDs-PpIX.

Molecular insights into the effects of focused ultrasound mechanotherapy on lipid bilayers: Unlocking the keys to design effective treatments

Administration of focused ultrasounds (US) represents an attractive complement to classical therapies for a wide range of maladies, from cancer to neurological pathologies, as they are non-invasive, easily targeted, their dosage is easy to control, and they involve low risks. Different mechanisms have been proposed for their activity but the direct effect of their interaction with cell membranes is not well understood at the molecular level. This is in part due to the difficulty of designing experiments able to probe the required spatio-temporal resolutions. Here we use Molecular Dynamics (MD) simulations at two resolution levels and machine learning (ML) classification tools to shed light on the effects that focused US mechanotherapy methods have over a range of lipid bilayers. Our results indicate that the dynamic-structural response of the membrane models to the mechanical perturbations caused by the sound waves strongly depends on the lipid composition. The analyses performed on the MD trajectories contribute to a better understanding of the behavior of lipid membranes, and to open up a path for the rational design of new therapies for the long list of diseases characterized by specific lipid profiles of pathological membrane cells.

Tumor Spheroids as Model to Design Acoustically Mediated Drug Therapies: A Review

Tumor spheroids as well as multicellular tumor spheroids (MCTSs) are promising 3D in vitro tumor models for drug screening, drug design, drug targeting, drug toxicity, and validation of drug delivery methods. These models partly reflect the tridimensional architecture of tumors, their heterogeneity and their microenvironment, which can alter the intratumoral biodistribution, pharmacokinetics, and pharmacodynamics of drugs. The present review first focuses on current spheroid formation methods and then on in vitro investigations exploiting spheroids and MCTS for designing and validating acoustically mediated drug therapies. We discuss the limitations of the current studies and future perspectives. Various spheroid formation methods enable the easy and reproducible generation of spheroids and MCTSs. The development and assessment of acoustically mediated drug therapies have been mainly demonstrated in spheroids made up of tumor cells only. Despite the promising results obtained with these spheroids, the successful evaluation of these therapies will need to be addressed in more relevant 3D vascular MCTS models using MCTS-on-chip platforms. These MTCSs will be generated from patient-derived cancer cells and nontumor cells, such as fibroblasts, adipocytes, and immune cells.

Ultrasound Triggers Hypericin Activation Leading to Multifaceted Anticancer Activity

The use of ultrasound (US) in combination with a responsive chemical agent (sonosensitizer) can selectively trigger the agent's anticancer activity in a process called sonodynamic therapy (SDT). SDT shares some properties with photodynamic therapy (PDT), which has been clinically approved, but sets itself apart because of its use of US rather than light to achieve better tissue penetration. SDT provides anticancer effects mainly via the sonosensitizer-mediated generation of reactive oxygen species (ROS), although the precise nature of the underpinning mechanism is still under debate. This work investigates the SDT anticancer activity of hypericin (Hyp) in vitro in two- (2D) and three-dimensional (3D) HT-29 colon cancer models, and uses PDT as a yardstick due to its well-known Hyp phototoxicity. The cancer cell uptake and cellular localization of Hyp were investigated first to determine the proper noncytotoxic concentration and incubation time of Hyp for SDT. Furthermore, ROS production, cell proliferation, and cell death were evaluated after Hyp was exposed to US. Since cancer relapse and transporter-mediated multidrug resistance (MDR) are important causes of cancer treatment failure, the US-mediated ability of Hyp to elicit immunogenic cell death (ICD) and overcome MDR was also investigated. SDT showed strong ROS-mediated anticancer activity 48 h after treatment in both the HT-29 models. Specific damage-associated molecular patterns that are consistent with ICD, such as calreticulin (CRT) exposure and high-mobility group box 1 protein (HMGB1) release, were observed after SDT with Hyp. Moreover, the expression of the ABC transporter, P-glycoprotein (P-gp), in HT-29/MDR cells was not able to hinder cancer cell responsiveness to SDT with Hyp. This work reveals, for the first time, the US responsiveness of Hyp with significant anticancer activity being displayed, making it a full-fledged sonosensitizer for the SDT of cancer.