Cell selectivity to laser-induced photoacoustic injury of skin

Cell selectivity to photoacoustic injury induced by argon-fluoride excimer laser (193 nm) was studied. Rats were irradiated through air or water and a 2.5 mm aperture. The laser was adjusted to deliver 150 mJ/cm2 at the skin surface with 12 and 24 pulses. Immediate damage was assessed by transmission electron microscopy. Cell selectivity was observed in dermis and epidermis. Fibroblasts showed alteration of nuclear chromatin and cytoplasmic organelles, while some of the migratory cells adjacent to fibroblasts did not. Similar difference of damage was observed between keratinocytes and Langerhans cells in epidermis. Considering the relationship between cells and their microenvironment in tissue, this selectivity may be due to the difference of acoustical coupling of propagation of acoustic waves rather than to differential sensitivity of the cells to damage.