Elucidation of Mechanisms for the Biostimulatory Effect of Low Level Laser Irradiation on Osteoblasts by Subtractive Gene Cloning

Abstract

Various biostimulatory effects of low-energy laser irradiation (LLLI) have been reported thatinvolve the acceleration of bone regeneration. We reported that LLLI stimulated cellular proliferation, bonenodule formation, alkaline phosphatase activity, and osteocalcin expression. However, the molecular basis ofthe mechanisms leading to these findings has not been elucidated. To accomplish this, we constructed thecDNA library of MC3T3-El, a clonal osteoblastic cell line, which enhanced gene expressions by LLLI using asubtracted gene cloning procedure. In the present study, we further characterized gene library by DNAnucleotide sequence and homology-search with a DNA database. Among 88 subtractive genes, several clonesexhibited high homology with mitochondrial protein genes, signal transduction-related genes, and EST genes.These findings may help to elucidate the molecular-based mechanisms for the biostimulatory effect of LLLI onosteoblasts.