31 Cellular and Molecular Biology Original Research Hypoxia and laser enhance expression of SDF-1 in muscles cells M. Mirahmadi 1 , N. Ahmadiankia 2 , H. Naderi-Meshkin 1 , A. Heirani-Tabasi 1 , H. R. Bidkhori 1 , P. Afsharian 3* , A. R. Bahrami 1,4* 1 Stem Cell and Regenerative Medicine Research Group, Iranian Academic Center for Education, Culture and Research (ACECR), Khorasan Razavi Branch, Mashhad, Iran 2 Shahroud University of Medical Sciences, Shahroud, Iran 3 Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR-Tehran, Iran 4 Cell and Molecular Biotechnology Research Group, Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran Abstract: Targeted homing of transplanted mesenchymal stem cells (MSCs) is a decades old discussion in regenerative medicine. It has been proved that stromal cell-derived factor-1 (SDF-1α) is a potent chemoattractant of MSCs. Therefore, different strategies have been used to increase secretion of SDF-1α in damaged tissues to elevate targeted homing of MSCs. Previous studies have revealed that increased SDF-1α expression in hypoxic necrotic tissues and also low-level laser exposure enhanced angiogenesis in injured tissues. Herein, human skeletal and cardiac muscle cells (HSKM and HCM) were treated with hypoxia and low level laser to see their effects on expression of SDF-1α and on MSCs migration towards these treated cells. The optimal treatment conditions were determined by investigating the cellular viability after treatment. Real-Time PCR and Western blot analysis were done to study the expression of SDF-1α in treated cells. Migration potential of MSCs toward hypoxic and laser treated cells was investigated via migration assay. MTT assay revealed that laser and hypoxia treatment had no effect on the viability of HCM, HSKM compared with Glioblastoma cells. Real-Time PCR showed 16- and 90-fold elevation in mRNA of SDF-1α in HSKM and HCM cells, respectively, in laser treated with 12 J/cm 2 intensity. In these two groups, selected as optimal conditions, HIF-1α expression showed maxi- mum fold changes that might be partly because of response to treatments help to SDF-1α expression. It can be concluded that hypoxia and laser treatments may recruit MSCs and applied as a useful strategy for the further targeted stem cell homing. Key words: Targeted Homing, Hypoxia, Laser, SDF-1α, Muscle cells, Mesenchymal stem cells. Introduction Stem cell therapy has been considered as a promi- sing tool for degenerative diseases and disorders as their self-renewal property has the potential to return an impaired organ to its proper functioning. Targeted stem cell therapy is a decades long discussion in stem cell transplantation to overcome the challenges like escape of cells etc. Finding techniques to enhance chemotaxis and retention of the implanted mesenchymal stem cells (MSCs) for maximum effectiveness in MSC based stem cell therapy is an evolving step in regenerative medicine. MSCs are multipotent adult stem cells having self-re- newal and multi-lineage differentiation potential. These cells have been preferred for stem cell therapy because of their regenerative potential, secreted growth factors and immunomodulatory role preventing immune cell activation (1,2). Various studies have proven the role of chemokine stromal cell-derived factor-1 (SDF-1α) in stem/progenitor cell chemotaxis and organ-specifc ho- ming of MSCs in ischemic tissue because of its cognate receptor CXC chemokine receptor 4 (CXCR4) located on the surface of MSCs (3–6). SDF-1α (stromal derived factor-1) is a small molecule, whose N-terminus binds and activates chemokine receptors especially CXCR4. The CXCR4 receptor is expressed on several cell types, including blood cells (i.e. lymphocytes, monocytes, etc.), haematopoietic stem cells (HSCs), and embryonic stem (ES) cells (7–9). In a number of studies, CXCR4 upregulation was observed in MSCs when they were ex- posed to hypoxia for a short duration of time (6,10,11). These pre-conditioned MSCs have been shown attrac- tants toward SDF-1α expression. All ischemic tissues expressed a signifcant amount of SDF-1α which attract MSCs for their regeneration mechanism. Search for non-invasive strategies to enhance SDF-1α expression and their validity for a number of tissues and cells may help to reduce challenges in stem cell therapy. In addi- tion to SDF-1-CXCR4 axis, HIF-1α as a transcription factor responsible to regulate the SDF-1α expression, plays signifcant role in cellular migration. Studies have described the Hypoxia as stabilizer of HIF-1α protein in later infammatory phases because ofHIF-1 binding sites in SDF-1α promoter. Thus, stabilized HIF-1 enhances SDF-1α expression in hypoxic/injured tissues initiating chemoattraction of CXCR4 + stem cells for the purpose of tissue repairing and regeneration (12).It has been pro- posed here that physical treatments like laser treatment and hypoxia may enhance SDF-1α expression which is an attractant of implanted MSCs and can be an alterna- tive to chemicals for targeted homing of implanted stem cells. It has been demonstrated in this study that cardiac and skeletal muscle cells showed enhanced expression of SDF-1α when treated with hypoxia and laser conclu- ding that hypoxic treatment or laser treatment can be a clinical strategy to made MSCs transplantation more Received, March 17 2016; Accepted, April 10 2016; Published April 30 2016 * Corresponding author: Ahmad Reza Bahrami, ar_bahrami@um.ac.ir and Parvaneh Asharian, Email: pafshar@royaninstitute.org Copyright: © 2016 by the C.M.B. Association. All rights reserved. Mirahmadi et al. Cell. Mol. Biol.2016, 62 (5): 31-37 ISSN: 1165-158X doi: 10.14715/cmb/2016.62.5.6