Low-level laser irradiation modulates the proliferation and the osteogenic differentiation of bone marrow mesenchymal stem cells under healthy and inflammatory condition

• Published in: Lasers in medical science Vol. 34; no. 1; pp. 169 - 178
• Main Authors: Wang, Liying, Wu, Fan, Liu, Chen, Song, Yang, Guo, Jiawen, Yang, Yanwei, Qiu, Yinong
• Format: Journal Article
• Language: English
• Published: London Springer London 01.02.2019; Springer Nature B.V
• Subjects: Alizarin; Alkaline phosphatase; Assaying; Biocompatibility; Biomedical materials; Bone marrow; Bone Marrow Cells - cytology; Cbfa-1 protein; Cell Differentiation - drug effects; Cell Differentiation - radiation effects; Cell proliferation; Cell Proliferation - drug effects; Cell Proliferation - radiation effects; Cells, Cultured; Dentistry; Differentiation (biology); Enzyme-linked immunosorbent assay; Humans; In vitro methods and tests; Inflammation; Inflammation - pathology; Interleukin-1 - metabolism; Irradiation; Lasers; Low-Level Light Therapy; Medicine; Medicine & Public Health; Mesenchymal stem cells; Mesenchymal Stem Cells - drug effects; Mesenchymal Stem Cells - metabolism; Mesenchymal Stem Cells - pathology; Mesenchymal Stem Cells - radiation effects; Mesenchyme; Microenvironments; Optical Devices; Optics; Original Article; Osteocalcin; Osteogenesis; Osteogenesis - drug effects; Osteogenesis - radiation effects; Photonics; Quantum Optics; Staining; Stem cells; Transplantation; Tumor Necrosis Factor-alpha - pharmacology; Tumor necrosis factor-TNF; Tumor necrosis factor-α; Inflammation; Proliferation; Bone marrow mesenchymal stem cells (BMSCs); Low-level laser therapy (LLLT); Osteogenesis
• DOI: 10.1007/s10103-018-2673-8
• ISSN: 0268-8921; 1435-604X

The aim of this in vitro study was to evaluate the effects of low-level laser therapy (LLLT) at different energy intensities on proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) under healthy and inflammatory microenvironments. Human BMSCs and BMSCs from inflammatory conditions (i-BMSCs, BMSCs treated with tumor necrosis factor α; TNF-α) were subject to LLLT (Nd:YAG;1064 nm) at different intensities. We designed one control group (without irradiation) and four testing groups (irradiation at 2, 4, 8, and 16 J/cm 2 ) for both BMSCs and i-BMSCs. Cell proliferation was measured using colony-forming unit fibroblast assay and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay. Osteogenic capacity of cells was determined by alkaline phosphatase (ALP) staining, ALP activity assay, Alizarin Red S staining and the mRNA transcript levels of genes runt-related transcription factor 2 (Runx2), ALP, and osteocalcin. Moreover, the effects of LLLT on secretion of TNF-α in BMSCs and i-BMSCs were measured by enzyme-linked immunosorbent assay. Our results demonstrated LLLT could significantly promote BMSC proliferation and osteogenesis at densities of 2 and 4 J/cm 2 . LLLT at density of 8 J/cm 2 could promote the proliferation and osteogenesis of i-BMSCs. However, LLLT at 16 J/cm 2 significantly suppressed the proliferation and osteogenesis of BMSCs both in healthy and in inflammatory microenvironment. Moreover, we also found that the expression of TNF-α was obviously inhibited by LLLT at 4, 8, and 16 J/cm 2 , in an inflammatory microenvironment. Considering these findings, LLLT could improve current in vitro methods of differentiating BMSCs under healthy and inflammatory microenvironments prior to transplantation.