Endoscopic non-ablative fractional laser therapy in an orthotopic colon tumour model.

Colorectal cancer is one of the leading causes of cancer-related deaths. Although several therapeutic management strategies are available at the early colon cancer stages, such as endoscopic mucosal or submucosal dissection, associated complications often include bleeding or bowel perforations. As an alternative approach, we investigated endoscopic non-ablative fractional laser (eNAFL) irradiation as a minimally invasive therapeutic modality for the treatment of early-stage colorectal cancer. By implanting SL4-DsRed colon cancer cells into the colons of the C57BL/6 mice, we developed an orthotopic colon tumour mouse model and demonstrated the early-stage tumour growth delay following the eNAFL irradiation. Additionally, we evaluated the temperature changes in the eNAFL-irradiated area using numerical simulations, and induced inflammation using histological analysis. Our results indicate a minimal thermal damage confined to the irradiated spot, sparing the adjacent tissue and alteration in the tumour microenvironment. eNAFL irradiation may be clinically useful as a minimally invasive therapeutic intervention at the early stage of tumourigenesis. In future, an optimal eNAFL therapeutic dose should be determined, in order to increase the efficacy of this approach.

In vivo study of optical speckle decorrelation time across depths in the mouse brain.

The strong optical scattering of biological tissue confounds our ability to focus light deeply into the brain beyond depths of a few hundred microns. This challenge can be potentially overcome by exploiting wavefront shaping techniques which allow light to be focused through or inside scattering media. However, these techniques require the scattering medium to be static, as changes in the arrangement of the scatterers between the wavefront recording and playback steps reduce the fidelity of the focus that is formed. Furthermore, as the thickness of the scattering medium increases, the influence of the dynamic nature becomes more severe due to the growing number of scattering events experienced by each photon. In this paper, by examining the scattering dynamics in the mouse brain in vivo via multispeckle diffusing wave spectroscopy (MSDWS) using a custom fiber probe that simulates a point-like source within the brain, we investigate the relationship between this decorrelation time and the depth of the point-like light source inside the living mouse brain at depths up to 3.2 mm.

Erratum: In vivo study of optical speckle decorrelation time across depths in the mouse brain: erratum.

[This corrects the article on p. 4855 in vol. 8.].