Low Level LASER Therapy Induces Therapeutic Angiogenesis in Diabetic Mice with Hindlimb Ischemia

Patients with diabetes mellitus (DM) are at high risk of developing peripheral arterial obstructive disease (PAOD) in lower extremities. Previous studies show low level LASER therapy (LLLT) can increase angiogenesis in vivo and in vitro. Here we performed hindlimb ischemia as PAOD model on diabetic mice to test the effects of LLLT. Twenty C57Bl/6 mice were randomly divided into four groups. Control group mice received femoral artery ligation/excision only. DM group mice were injected with Streptozocin (STZ) to induce diabetes followed by femoral artery ligation/excision. LLLT group mice received femoral artery ligation/excision and the lower limbs received LASER treatment for five days (660nm, 10 min, 1.91 J/cm2) started from second day postoperatively. DM+LLLT group mice were received femoral artery ligation/excision and LASER treatment after diabetes induced. Three days after LASER treatment finished, limb blood flow was measured by Laser Doppler perfusion imaging. Capillary density was assessed by immunofluorescence staining. CD31, VEGF, HIF-1, phospho-ERK, iNOS and eNOS protein level was examined by Western blot. Blood perfusion, capillary density, CD31, and VEGF protein levels were significantly higher in those groups received LLLT compared to control and DM group. Low level LASER significantly increased ERK phosphorylation and HIF-1 expression. In addition, phospho-eNOS was increased but iNOS protein level was decreased in mice received LASER treatment. In summary, the ability of low level LASER to induce therapeutic angiogenesis in diabetic mice suggested this approach deserves investigation as a novel approach to treat PAOD patients.