Modulation Of Stem Cell Niche And Stem Cell Migration Promotes Functional Angiogenesis By Enhancing Stem Cell Homing In Ischemic Rat Myocardium: A Novel Concept Of Cell-Free Regeneration Therapy

Background: The microenvironments composed of extracellular matrix (ECM) components and cytokines are considered to be involved in the decision of the stem cell fate and behavior. In addition, some cytokines induced by ONO1301 has been reported to enhance cell migration contributing to myocardial regeneration. In this study, we hypothesized that combined administration of cardiac specific ECM such as laminins and ONO1301 may enhance regeneration process by modulation of stem cell activity and homing. Methods and Results: In vitro study revealed that MSCs showed strong adhesion to laminin (LM) 511. ONO1301 promoted the production of several cytokines in smooth muscle cells, and it enhanced MSCs migration in vitro assay. To examine the therapeutic effect of ONO1301 combined with LM511, we transplanted ONO1301 or ONO1301 with LM511 (n=5-12) in a rat acute myocardial infarction model. Four weeks later, the number of PDGFRα- and CD90-positive cells tended to be higher in the combination (ONO1301 with LM511) group than in the ONO1301 alone group. Furthermore the gene expression of Sca-1 and c-kit was higher in the combination group than the control group (Sca-1, ONO1301 with LM511: 2.16- (p<0.05), ONO1301 alone: 2.01-fold to the control, c-kit, ONO1301 with LM511: 2.75- (p<0.05), ONO1301 alone: 1.45-fold to the control). Histological examination revealed that the number of ILB4 (endothelial cell marker) positive cells was significantly higher in the combination group than in the ONO1301 group (ONO1301 with LM511: 521±68 cells/mm 2 , ONO1301 alone: 281±10 cells/mm 2 , control: 195±29 cells/mm 2 ; p<0.05). Moreover, the number of CD31 (endothelial cell marker) and SMA (smooth muscle cell marker) double positive cell was significantly higher in the combination group compared with the control group (ONO1301 with LM511: 616±44 cells/mm 2 , control: 226±60 cells/mm 2 ; p<0.05). Real time PCR analysis revealed that SDF-1, PGF, FGF2 and HGF were higher in the combination group. Moreover, infarct size tended to be smaller in the combination group than in the ONO1301 group. Conclusion: The cell free regeneration therapy using both ONO1301 and LM511 may contribute to enhanced stem cell homing to implanted site, leading to improve functional angiogenesis in rat ischemic heart.