Spatial and Temporal Control of Cavitation Allows High In Vitro Transfection Efficiency in the Absence of Transfection Reagents or Contrast Agents

Pancreatic ductal adenocarcinoma (PDAC) is supported by a complex microenvironment whose physical contribution to chemoresistance could be overcome by ultrasound (US) therapy. This study aims to investigate the ability of US-induced inertial cavitation in association with chemotherapy to alter tumor cell viability via microenvironment disruption. For this purpose, we used a 3D-coculture PDAC model partially mimicking the tumor and its microenvironment. Coculture spheroids combining DT66066 cells isolated from KPC-transgenic mice and murine embryonic fibroblasts (iMEF) were obtained by using a magnetic nanoshuttle method. Spheroids were exposed to US with incremental inertial cavitation indexes. Conditions studied included control, gemcitabine, US-cavitation and US-cavitation + gemcitabine. Spheroid viability was assessed by the reduction of resazurin and flow cytometry. The 3D-coculture spheroid model incorporated activated fibroblasts and produced type 1-collagen, thus providing a partial miniature representation of tumors with their microenvironment. Main findings were: (a) Gemcitabine (5 μM) was significantly less cytotoxic in the presence of KPC/iMEFs spheroids compared with KPC (fibroblast-free) spheroids; (b) US-induced inertial cavitation combined with Gemcitabine significantly decreased spheroid viability compared to Gemcitabine alone; (c) both cavitation and chemotherapy affected KPC cell viability but not that of fibroblasts, confirming the protective role of the latter vis-à-vis tumor cells. Gemcitabine toxicity is enhanced when cocultured spheroids of KPC and iMEF are exposed to US-cavitation. Although the model used is only a partial representation of PDAC, this experience supports the hypothesis that US-inertial cavitation can enhance drug penetration and cytotoxicity by disrupting PDAC microenvironment.

Section: Methodsmentioning

confidence: 99%

Ultrasound-induced Cavitation enhances the efficacy of Chemotherapy in a 3D Model of Pancreatic Ductal Adenocarcinoma with its microenvironment

Leenhardt

Camus

Mestas

et al. 2019

“…MR-guided focused ultrasound has also been proposed as a non-invasive method of thalamotomy for the treatment of Essential Tremor 9–11 . Low-energy ultrasound (LEUS) can be applied for drug-delivery enhancement in tumors 12,13 , BBB disruption 14 and modulation of some cell dynamics 15,16 .…”

Section: Introductionmentioning

confidence: 99%

A causal study of the phenomenon of ultrasound neurostimulation applied to an in vivo invertebrate nervous model

Vion-Bailly

N’Djin

Castellanos

et al. 2019

Self Cite

Focused ultrasound are considered to be a promising tool for the treatment of neurological conditions, overcoming the limitations of current neurostimulation techniques in terms of spatial resolution and invasiveness. Much evidence to support the feasibility of ultrasound activation of neurons at the systemic level has already been provided, but to this day, the biophysical mechanisms underlying ultrasound neurostimulation are still widely unknown. In order to be able to establish a clear and robust causality between acoustic parameters of the excitation and neurobiological characteristics of the response, it is necessary to work at the cellular level, or alternatively on very simple animal models. The study reported here responds to three objectives. Firstly, to propose a simple nervous model for the study of the ultrasound neurostimulation phenomenon, associated with a clear and simple experimental protocol. Secondly, to compare the characteristics of this model’s nervous response to ultrasound neurostimulation with its nervous response to mechanical and electrical stimulation. Thirdly, to study the role played by certain acoustic parameters in the success rate of the phenomenon of ultrasound stimulation. The feasibility of generating action potentials (APs) in the giant axons of an earthworm’s ventral nerve cord, using pulsed ultrasound stimuli (f = 1.1 MHz, Ncycles = 175–1150, PRF = 25–125 Hz, Npulses = 20, PA = 2.5–7.3 MPa), was demonstrated. The time of generation (TOG) of APs associated with ultrasound stimulation was found to be significantly shorter and more stable than the TOG associated with mechanical stimulation (p < 0.001). By applying a causal approach to interpret the results of this study, it was concluded that, in this model, the nervous response to focused ultrasound is initiated along the afferent neurons, in between the mechanosensors and the synaptic connections with the giant axons. Additionally, early results are provided, highlighting a trend for the success rate of ultrasound neurostimulation and number of APs triggered per response to increase with increasing pulse repetition frequency (p < 0.05 and p < 0.001, respectively), increasing pulse duration and increasing pulse amplitude.

“…Such applications include tumor ablation 45 , permeation of tissue matrix for enhanced stem cell delivery or migration, bubble-enhanced poration of cells, i.e. sonoporation 46 , transfection of genetic material 47 or even modifying gene expression by stimulating ultrasound 48 . Moreover, cavitation-induced shock waves and associated shear forces, arising from imploding cavitation bubbles 49 , could be employed for lithotripsy 50 or controlled softening of calcified vessels 51 with spatially precise and localized mechanical stress gradients 52 .…”

Section: Discussionmentioning

confidence: 99%

Ultrasonic actuation of a fine-needle improves biopsy yield

Perra

Lampsijärvi

Barreto

et al. 2021

Despite the ubiquitous use over the past 150 years, the functions of the current medical needle are facilitated only by mechanical shear and cutting by the needle tip, i.e. the lancet. In this study, we demonstrate how nonlinear ultrasonics (NLU) extends the functionality of the medical needle far beyond its present capability. The NLU actions were found to be localized to the proximity of the needle tip, the SonoLancet, but the effects extend to several millimeters from the physical needle boundary. The observed nonlinear phenomena, transient cavitation, fluid streams, translation of micro- and nanoparticles and atomization, were quantitatively characterized. In the fine-needle biopsy application, the SonoLancet contributed to obtaining tissue cores with an increase in tissue yield by 3–6× in different tissue types compared to conventional needle biopsy technique using the same 21G needle. In conclusion, the SonoLancet could be of interest to several other medical applications, including drug or gene delivery, cell modulation, and minimally invasive surgical procedures.