Infrared (780 nm) low Level Laser Therapy for Wound Healing: In Vivo and in Vitro Studies

The potential therapeutic effect of 780 nm low power diode laser irradiation (LPDLI) was evaluated in vivo on wound healing, and in vitro on proliferation of cultured normal human fibroblasts (NHF) and keratinocytes (NHK). In five patients suffering from cutaneous fissures (F patients) one fissure in each patient was irradiated along the length of the fissure every 2 or 3 days, using 780 nm LPDLI, 30 mW, 30 sec per point. Fissures located on the opposite side of the body served as controls. In vitro, NHF and NHK were irradiated with this diode laser, via a fibreoptic light guide (25 mW) for 0-20 sec. Complete closure occurred in 80% of irradiated fissures, and in 60% of controls. Initial healing (25% closure) occurred earlier, at 2.2± 1.1 days in irradiated fissures vs. 3.5 ±0.9 days (p < 0.06)in the nonirradiated fissures, but the timing of complete healing did not differ significantly between the two groups. In vitro, a single laser exposure to NHK (2-7 sec) and NHF (9-10 sec) increased proliferation parameters compared with sham-irradiated controls: ³H-Thymidine incorporation at 6-24 hours by 2.29±0.31 (p.001); the percentage of dividing cells at 24 hours by 1.55±0.11 (p < 0.05); and cell numbers at 48 hrs by 1.45±0.07 (p < 0.01). These results suggest that 780 nm LPDLI irradiation promotes wound healing, presumably by enhancing proliferation of fibroblasts and keratinocytes.