[This corrects the article DOI: 10.1155/2017/4107587.].

After seven‐day exposure to 0.5‐Tesla Static Magnetic Field (SMF), Adipose‐derived Stem Cells (ASCs) and those labeled by superparamagnetic iron oxide (SPIO) nanoparticles were examined for viability by methyl thiazol tetrazolium (MTT) assay, proliferation by cell counting and bromodeoxyuridine (BrdU) incorporation, DNA integrity by single cell gel electrophoresis, surface antigen by flow cytometry analysis, and the expression of cytokines and genetic markers by reverse transcription‐PCR and underwent adipogenic and osteogenic differentiation assessed by quantifying related specific genes expression. The SMF slightly reduced cell viability and proliferation and inhibited the expression of CD49d, CD54, and CD73 but did not damage DNA integrity. The SMF slightly downregulated the expression of cytokines including Vascular Endothelial Growth Factor (VEGF), Insulin‐like Growth Factor‐1 (IGF‐1), Transforming Growth Factor Beta 1 (TGF‐β1), genetic markers comprising Stem Cell Antigen‐1 (Sca1), Octamer‐4 (Oct‐4), ATP‐binding Cassette Subfamily B Member 1 (ABCB1), adipogenic marker genes containing Lipoprotein Lipase (LPL), Peroxisome Proliferator‐Activated Receptor Gamma (PPAR‐γ), and osteogenic marker genes including Secreted Phosphor‐protein 1 (SPP1) and Osterix (OSX). Exposure to 0.5 T SMF for seven days inhibited viability, proliferation, surface antigen expression, cytokine secretion, stem cell genetic marker expression, and adipogenic and osteogenic differentiation but did not affect the DNA integrity in ASCs with or without SPIO labeling.

Although adipose-derived stem cells (ASCs) hold the promise of effective therapy for myocardial infarction, low cardiac retention of implanted ASCs has hindered their therapeutic efficiency. We investigated whether an externally applied static magnetic field (SMF) enhances cardiac localization of "magnetic" cells and promotes heart function recovery when ASCs are preloaded with superparamagnetic iron oxide (SPIO) nanoparticles. The influence of SMF (0.1 Tesla) on the biological activities of SPIO-labeled ASCs (SPIOASCs) was investigated first. Fifty-six female rats with myocardial infarction underwent intramyocardial injection of cell culture medium (CCM) or male SPIOASCs with or without the subcutaneous implantable magnet (CCM-magnet or SPIOASC-magnet). Four weeks later, endothelial differentiation, angiogenic cytokine secretion, angiogenesis, cardiomyocyte apoptosis, cell retention, and cardiac performance were examined. The 0.1-Tsela SMF did not adversely affect the viability, proliferation, angiogenic cytokine secretion, and DNA integrity of SPIOASCs. The implanted SPIOASCs could differentiate into endothelial cell, incorporate into newly formed vessels, and secrete multiple angiogenic cytokines. Four weeks after cell transplantation, the number of cardiac SPIOASCs was significantly increased, vascular density was markedly enlarged, fewer apoptotic cardiomyocytes were present, and heart contractile function was substantially improved in the SPIOASC-magnet treated rats in comparison with the SPIOASC-treated rats. The SPIOASCs could differentiate into endothelial cells, incorporate into vessels, promote angiogenesis, and inhibit ischemic cardiomyocyte apoptosis. An externally applied SMF offered a secure environment for biological properties of SPIOASCs, increased the cardiac retention of implanted magnetic SPIOASCs, and further enhanced heart function recovery after myocardial infarction. Significance: This pilot proof-of-concept study suggests that a 0.1-Tesla static magnetic field does not adversely affect the viability, proliferation, angiogenic cytokine secretion, or DNA integrity of the superparamagnetic iron oxide-labeled adipose-derived stem cells (SPIOASCs). Implantation of adipose-derived stem cells promotes myocardial neovascularization and inhibits ischemic cardiomyocyte apoptosis through endothelial differentiation, incorporation into vessels, and paracrine factor secretion. An externally applied static magnetic field enhanced myocardial retention of intramyocardially injected "magnetic" SPIOASCs and promoted cardiac function recovery after myocardial infarction. With further preclinical optimization, this approach may improve the outcome of current stem cell therapy for ischemic myocardial infarction.

Original Article Overexpression of integrin β₂ improves migration and engraftment of adipose-derived stem cells and augments angiogenesis in myocardial infarction Zihui Yuan, Kai Yan, Jian Wang