Cellular expression of integrin-β1 is of critical importance for inducing therapeutic angiogenesis by cell implantation

Objectives: Using cell-based therapy to induce therapeutic angiogenesis has been the focus of much recent attention. We used freshly collected CD117-positive stem cells (CD117(+) cells) and ex vivo expanded CD117(+) cells to investigate the role of cellular expression of several adhesion molecules in this therapeutic regimen. Methods: CD117(+) cells were separated from the bone marrow mononuclear cells of C57/BL6 mice and cell expansion was done by 2 weeks of cultivation. The cellular expression of integrin-beta(1), integrin-beta(3) and VE-cadherin was analyzed by Western blot and real-time PCR. Three-dimensional culture was performed to observe the capillary-like tube formation. We also implanted cells into the ischemic limbs of mice and evaluated the survival and incorporation of these implanted cells and measured the blood flow and microvessel density of the ischemic limbs 2 weeks after treatment. Results: The expression of integrin-beta(1) in the expanded cells decreased significantly, to about 30% of the freshly unexpanded CD117(+) cells. However, the expression of integrin-beta(3) did not change significantly and the VE-cadherin increased after ex vivo expansion of the CD117(+) cells. Antibody perturbation to integrin-beta(1) significantly inhibited the adhesion, growth and tube formation of cultured CD117(+) cells. Furthermore, the freshly unexpanded CD117(+) cells survived well and were incorporated in microvessels after implantation into the ischemic limbs of mice, resulting in a significant increase in blood flow and microvessel density. The cell survival and incorporation decreased, and the angiogenic potency was deprived by antibody perturbation to integrin-beta(1) before implantation. Conversely, these expanded cells had weak angiogenic potency because of the poor cell survival and incorporation after implantation, but the increase in integrin-beta(1) expression by subjecting them to 24-h hypoxia prestimulation increased cell survival and angiogenic potency significantly after implantation into the ischemic limbs. Conclusion: These data clearly show that integrin-beta(1) is a critical adhesion molecule for inducing therapeutic angiogenesis in cell-based therapy, by regulating cell survival and differentiation after implantation into ischemic tissue. (C) 2004 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.