X-ray-induced bio-acoustic emissions from cultured cells

Abstract

Purpose

We characterize for the first time the emission of acoustic waves from cultured cells irradiated with X-ray photon radiation.

Methods and materials

Human cancer cell lines (MCF-7, HL-60) and control cell-free media were exposed to 1 Gy X-ray photons while recording the sound generated before, during and after irradiation using custom large-bandwidth ultrasound transducer. The effects of dose rate and cell viability were investigated.

Results

We report the first recorded acoustic signals captured from a collective pressure wave response to ionizing irradiation in cell culture. The acoustic signal was co-terminous with the radiation pulse, its magnitude was dependent on radiation dose rate, and live and dead cells showed qualitatively and quantitatively different acoustic signal characteristics. The signature of the collective acoustic peaks was temporally wider and with higher acoustic power for irradiated HL-60 than for irradiated MCF-7.

Conclusions

We show that X-ray irradiation induces two cultured cancer cell types to emit a characteristic acoustic signal for the duration of the radiation pulse. The rapid decay of the signal excludes acoustic emissions themselves from contributing to the inter-organism bystander signal previously reported in intact animals, but they remain a potential component of the bystander process in tissues and cell cultures. This preliminary study suggests that further work on the potential role of radiation-induced acoustic emission (RIAE) in the inter-cellular bystander effect is merited.

Keywords:

• Bio-acoustics
• radiation induced acoustic emission (RIAE)
• bio-phonon
• phonon
• mechanotransduction
• cellular stress response
• ionizing radiation

Acknowledgments

We gratefully acknowledge the excellent technical support of Annette Preston and the generosity of Dr Jane Dobson and the Queens Veterinary School Hospital, Cambridge University Department of Veterinary Medicine for access to the Varian Clinac 2100.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data deposition

Data are deposited in STOREDB DOI:10.20348/STOREDB/1169. Individual files can be accessed on:

STOREDB:DATASET1245 Raw Picoscope data [DOI:10.20348/STOREDB/1169/1245].

Data availability statement

Raw acoustic data and measurements of extracellular Lactate dehydrogenase and mitochondrial membrane depolarization are available from the STORE database.

Additional information

Funding

Work in the laboratory of CM is funded by the Canadian NSERC Discovery Fund Grant 660340.

Notes on contributors

Bruno F. E. Matarèse

Dr. Bruno Matarèse is a physicist in biology and medicine with a particular interest in radiobiology and the use of combined electromagnetic and acoustic technology for early detection of cancer.

Hassan Rahmoune

Dr. Hassan Rahmoune is a cell biologist at the Department of Chemical Engineering and Biotechnology at Cambridge University with particular interest in engineering and biomedical research.

Nguyen T. K. Vo

Dr. Nguyen Vo was a research associate in the Department of Biology at McMaster University and is currently a research associate in the Department of Biology at the University of Waterloo. He is currently part of a research team mapping the acquired immunity profile for COVID19 in a campus population.

Colin B. Seymour

Prof. Colin Seymour is a radiobiologist with a special interest in low dose effects of radiation. He is a professor in the Department of Biology at McMaster University.

Paul N. Schofield

Prof. Paul Schofield is Professor in Biomedical Informatics at the University of Cambridge and Adjunct Professor at the Jackson Laboratory, Bar Harbor, USA.

Carmel Mothersill

Prof. Carmel Mothersill is a radiobiologist with a particular interest in low dose and non-targeted effects of radiation in the environment. She is a professor in the Department of Biology at McMaster University.