FTIR spectral imaging as a probe of ultrasound effect on cells in vitro.

Abstract

Safe and efficient intracellular delivery of genes or drugs is critically important in targeted cancer treatment and gene therapy applications. Ultrasound (US) has been demonstrated to alter the cell membrane permeability due to a biophysical mechanism (Sonoporation) and exploited as a promising non-invasive gene transfer method. The sonoporation process could induce the formation of transient pores without significantly affecting cell viability.This research is aimed at investigating some bioeffects due to Therapeutic Ultrasound (pulsed-1 MHz) which could allow to enhance drugs or genes delivery in a non tumoral cell line. We have used the NIH-3T3 cell line as model system and exposed it to US at two different distances from the source;  the effects of this pulsed ultrasonic wave on cells were assessed by Fourier transform infrared (FT-IR) spectroscopic imaging analysis. This technique combined with a focal plane array (FPA) detector  has been widely used to study the general biochemical changes in vitro; moreover, the development of FPA detectors and shortening of measurement times specifically for IR imaging, from several hours to few minutes, have made possible to image the distribution of molecular species in biological samples. We have also performed a cytokinesis-block micronucleus (CBMN) assay to reveal the presence or not of micronuclei (named Howell-Jolly bodies) formed during the cell division due to the DNA damage. The results of IR analysis combined with the cytogenetic analysis have shown that these experimental conditions can not cause DNA mutations in the NIH-3T3 cell line. Finally, the comparison between the spectral parameters of the average spectrum extracted from the spectral map and those of the set of all spectra from the spectral map could be limited by the presence of bad pixels inside the map.