Abstract
Objective: The aim of the present study was to evaluate the possible beneficial effects of implantation of laser-irradiated mesenchymal stem cells (MSCs) into the infarcted rat heart. Background data: It was demonstrated that Low-level laser therapy (LLLT) upregulates cytoprotective factors in ischemic tissues. Materials and Methods: MSCs were isolated from rat bone marrow and grown in culture. The cells were laser irradiated with Ga-Al-As laser (810nm wavelength), labeled with 5-Bromo-2'deoxyuridine (BrdU), and then implanted into infarcted rat hearts. Non-irradiated cells were similarly labeled and acted as control. Hearts were excised three weeks later and cells were stained for BrdU and c-kit immunoreactivity. Results: Infarcted hearts that were implanted with laser-treated cells showed a significant reduction of 53% in infarct size compared to hearts that were implanted with non-laser-treated cells. The hearts implanted with laser-treated cells prior to implantation demonstrated a 5 and 6.3-fold significant increase in cell density that positively immunoreacted to BrdU and c-kit, respectively, as compared to hearts implanted with non-laser-treated cells. A significantly 1.4 and 2-fold higher level of angiogenesis and vascular endothelial growth factor, respectively, was observed in infarcted hearts that were implanted with laser-treated cells as compared to non-treated implanted cells. Conclusion: The findings of the present study provide the first evidence that LLLT can significantly increase survival and/or proliferation of MSCs post implantation into the ischemic/infarcted heart, followed by a marked reduction of scarring, and enhanced angiogenesis. The mechanisms associated with this phenomenon remain to be elucidated in further studies.
