In vitro potentiation of doxorubicin by unseeded controlled non-inertial ultrasound cavitation

Abstract

Ultrasound-generated non-inertial cavitation has the ability to potentiate the therapeutic effects of cytotoxic drugs. We report a novel strategy to induce and regulate unseeded (without nucleation agents) non-inertial cavitation, where cavitation is initiated, monitored and regulated using a confocal ultrasound setup controlled by an instrumentation platform and a PC programmed feedback control loop. We demonstrate, using 4T1 murine mammary carcinoma as model cell line, that unseeded non-inertial cavitation potentiates the cytotoxicity of doxorubicin, one of the most potent drugs used in the treatment of solid tumors including breast cancer. Combined treatment with doxorubicin and unseeded non-inertial cavitation significantly reduced cell viability and proliferation at 72 h. A mechanistic study of the potential mechanisms of action of the combined treatment identified the presence of cavitation as required to enhance doxorubicin efficacy, but ruled out the influence of changes in doxorubicin uptake, temperature increase, hydroxyl radical production and nuclear membrane modifications on the treatment outcome. The developed strategy for the reproducible generation and maintenance of unseeded cavitation makes it an attractive method as potential preclinical and clinical treatment modality to locally potentiate doxorubicin.

Effect of Therapeutic Ultrasound on the Release of Insulin, Glucagon, and Alpha‐Amylase from Ex Vivo Pancreatic Models

“…Ultrasound (US), applied at therapeutic energy levels, has been extensively investigated for diverse medical and clinical applications. This technology allows for the design of targeted, non‐, or minimally invasive strategies for various therapeutic purposes such as tissue ablation, 8,9 enhanced drug delivery, 10,11 cancer immunotherapy, 12 and wound healing, 13 among others 14 . In addition, low‐intensity applications of US have been increasingly explored for safe and efficient stimulation and modulation of cellular activity 15–17 .…”

Pancreatic Ductal Adenocarcinoma: Current and Emerging Therapeutic Uses of Focused Ultrasound

“…Better characterization of the tumor mechanical properties (e.g., using elastography) might give insight on the expected tumor response to the mechanical effects of FUS. Moreover, recent breakthroughs in localizing [ 85 , 116 ], imaging [ 117 , 118 , 119 , 120 , 121 , 122 ], controlling [ 123 , 124 ], and quantifying [ 125 , 126 , 127 ] cavitation activity will most certainly improve the level of control of those mechanical effects, increase reliability, and allow fine tuning of the US parameters; while a limited amount of clinical data are currently available regarding drug delivery to pancreatic cancer, the increasing body of preclinical data and the use of ultrasound in drug delivery and other therapeutic applications suggest an increase in clinical studies being conducted in the near future.…”

Proof of Concept: Protein Delivery into Human Erythrocytes Using Stable Cavitation

“…For each pulse, the 600 μs signals were acquired with a sampling frequency of 32 MHz. A stable cavitation regulation scheme, extensively described in a previous report, was used. ,, Briefly, this regulation scheme relies on two modes: high pressure pulses (hereafter termed “bursting pulses”) aimed at creating a cavitation cloud alternating with moderate pressure pulses aimed at sustaining the bubble oscillation (hereafter termed “regulation pulses”). Stable cavitation was considered present if the peak in the 540–560 kHz subharmonic frequency range (half the emission frequency) was at least 3 dB above the average level of the neighboring broadband signal (560–600 kHz).…”

“…The inertial cavitation index (CI) corresponded to the 0.1–7.1 MHz broadband signal, in dB. The stable CI corresponded to the average level of the subharmonic peak in the 540–560 kHz range above the 560–600 kHz broadband signal …”