Blood-derived smooth muscle cells as a target for gene delivery

ObjectiveTo examine the feasibility of using blood-derived smooth muscle cells (BD-SMCs) as a target for to deliver therapeutic proteins.Materials and MethodsMononuclear cells (MNC) were isolated from peripheral blood. The outgrowth colonies from MNC culture were differentiated into BD-SMCs in media containing platelet-derived growth factor BB. Phenotypic characterization of BD-SMCs was assessed by immunocytochemistry. Cell proliferation, gene transfer efficiency with a retroviral vector, apoptosis, and the biological activity of the transduced gene product from the BD-SMCs were evaluated in vitro and in vivo in comparison with vascular derived SMC (VSMCs).ResultsBD-SMCs stained positive for SMC markers. No significant difference was observed between BD-SMCs and VSMCs in cell proliferation, migration, adhesiveness, and gene transfer efficiency. After BD-SMCs were transduced with a retroviral vector carrying the secreted alkaline phosphatase gene (SEAP), 174 ± 50 μg biologically active SEAP was produced per 106 cells over 24 hours. After injecting 5 × 106 cells expressing SEAP intravenously into rabbits, SEAP concentration increased significantly in the circulation from 0.14 ± 0.04 μg/ml to 2.34 ± 0.16 μg/ml 3 days after cell injection (P < .01, n = 3). Circulating levels of SEAP decreased to 1.76 μg /ml 1 week later and remained at this level up to 8 weeks, then declined to pre-cell injection level at 12 weeks. VSMC in vivo gene expression data were equivalent.ConclusionBD-SMCs have similar characteristics to mature VSMCs and can be used as a novel target for gene transfer to deliver a therapeutic protein.

Clinical RelevanceCell-based therapy strategies offer the potential to correct a wide spectrum of inherited and acquired human diseases. Translation to a clinical trial will require a detailed preclinical study to understand the characteristics of the isolated cells. BD-SMCs are practical and effective targets for ex vivo genetic engineering. They are obtained with ease by phlebotomy, eliminating the need for surgical tissue explantation. This study tested the suitability of BD-SMC in vivo as a target for gene therapy. The outcome of the study has direct application in progenitor cell-based therapy.