Enhanced Liver Regeneration Following Acute Hepatectomy by Low-Level Laser Therapy

Objective: The aim of the present study was to investigate the effect of low-level laser therapy (LLLT) on liver regeneration following hepatectomy. Background: LLLT has been found to modulate various biological processes. Materials and Methods: Twelve mature male rats were used. The liver was exposed, and 70% of it was excised. The rats were assigned randomly to two groups: control, non-laser treated, and experimental, laser-treated (diode [Ga-Al-As] laser 804 nm) group. For determination of newly formed blood vessels and proliferating cells, 5-Bromo-2'-deoxyuridine (BrdU) was injected intraperitoneally. The rats were sacrificed 2 d post hepatectomy, and histological sections from each liver were processed for analysis of new blood-vessel formation using BrdU immunostaining kit. Mesenchymal stem cells (MSCs) were assessed using c-kit immunostaining. BrdU-labeled cells were counted as for estimation of newly formed hepatic cells. Results: It was found that the number of proliferating cells (BrdU positive cells) per area in the regenerating regions of the livers were significantly (p<0.01) 2.6-fold higher in the laser-treated rats than in the control non-laser-treated rats. The density of the newly formed blood vessels and c-kit immunopositive cells in the regenerating area of the laser-treated livers was significantly (p<0.01) 3.3- and 2.3-fold respectively higher than the control non-laser treated livers. Conclusion: It is concluded that LLLT following acute hepatectomy most probably stimulates a significant enhancement of liver regeneration conducive to both the formation of new hepatocytes and MSCs and angiogenesis in the regenerating liver.