Low-power helium : neon laser irradiation enhances production of vascular endothelial growth factor and promotes growth of endothelial cells in vitro

Background and Objective: Numerous reports suggest that low-power laser irr adiation (LPLI) is capable of affecting cellular processes in the absence o f significant thermal effect. The objective of the present study was to det ermine the effect of LPLI on secretion of vascular endothelial growth facto r (VEGF) and proliferation of human endothelial cells (EC) in vitro. Study Design/Materials and Methods: Cell cultures were irradiated with sing le different doses of LPLI (Laser irradiance from 0.10 to 6.3 J/cm(2)) by u sing a He:Ne continuous wave laser (632 nm). VEGF secretion by smooth muscl e cells (SMC) and fibroblasts was quantified by sandwich enzyme immunoassay technique. The endothelial cell proliferation was measured by Alamar Blue assay. VEGF and transforming growth factor beta (TGF-beta) expression by ca rdiomyocytes was studied by reverse transcription-polymerase chain reaction (RT-PCR). Results: We observed that (1) LPLI of vascular and cardiac cells results in a statistically significant increase of VEGF secretion in culture (1.6-fol d for SMC and fibroblasts and 7-fold for cardiomyocytes) and is dose depend ent (maximal effect was observed with LPLI irradiance of 0.5 J/cm(2) for SM C, 2.1 J/cm(2) for fibroblasts and 1.05 J/cm(2) for cardiomyocytes). (2) Si gnificant stimulation of endothelial cell growth was obtained with LPLI-tre ated conditioned medium of SMC (maximal increase was observed with LPLI con ditioned medium with irradiance of 1.05 J/ cm(2) for SMC and 2.1 J/cm(2) fo r fibroblasts. Conclusion: Our studies demonstrate that low-power laser irradiation increa ses production of VEGF by SMC, fibroblasts, and cardiac myocytes and stimul ates EC growth in culture. These data may have significant importance leadi ng to the establishment of new methods for endoluminal postangioplasty vasc ular repair and myocardial photoangiogenesis. Lasers Surg. Med. 28:355-364, 2001. (C) 2001 Wiley-Liss, Inc.