Gut mucosa is an important interface between body and environment. Immune response and healing processes of murine small intestinal mucosa were investigated by intravital time-lapse two-photon excited autofluorescence microscopy of the response to localized laser-induced damage. Epithelial lesions were created by 355-nm, 500-ps pulses from a microchip laser that produced minute cavitation bubbles. Size and dynamics of these bubbles were monitored using a novel interferometric backscattering technique with 80 nm resolution. Small bubbles (< 2.5 µm maximum radius) merely resulted in autofluorescence loss of the target cell. Larger bubbles (7-25 µm) affected several cells and provoked immigration of immune cells (polymorphonuclear leucocytes). Damaged cells were expelled into the lumen, and the epithelium healed within 2 hours by stretching and migration of adjacent epithelial cells.
Keywords: (170.1020) Ablation of tissue; (170.2520) Fluorescence microscopy; (170.2680) Gastrointestinal; (170.3880) Medical and biological imaging; (170.4520) Optical confinement and manipulation; (180.4315) Nonlinear microscopy; (350.3390) Laser materials processing; (350.4855) Optical tweezers or optical manipulation.