Analysis of biomodulative effects of low intensity laser on human skin fibroblast cells using fiber-optic nano-probes

Over the past few decades, many efforts were devoted to study low power laser and cellular interaction. Some of the investigations were performed on cell populations. In this work fiber-optic based nano-probe is used for the precise delivery of laser light on to a single cell and the mechanism of light interaction with the cell during irradiation was studied. A human skin fibroblast cell line was utilized in this investigation. The human fibroblasts were irradiated under two different schemes of exposure: (1) entire cell population was irradiated within a Petri dish using a fan beam, (2) laser energy was precisely delivered on to a single cell using fiber-optic nano-probe. Studies were conducted by variation of laser intensity, exposure time, and the energy dose of exposure. Proliferative effect of laser irradiation was determined through cell counting for both exposure schemes. Enhancement of the rate of proliferation was observed to be dependent on laser parameters and method of laser delivery. Variation of total energy dose had greater effect on the enhancement of the rate of cellular proliferation compared to that of laser intensity. The photobiostimulative effect was also observed to have a finite life-time. Fluorescent life-time imaging of reactive oxygen species (ROS) was performed during the single cell exposure method. ROS generation was found to depend strongly on both laser energy doses and irradiation time. It is demonstrated in this communication that by using specially engineered nano-probes, laser light can be precisely delivered on to a targeted single cell.