CHARACTERIZATION OF HEMATOPOIETIC-CELLS ARISING ON THE TEXTURED SURFACE OF LEFT-VENTRICULAR ASSIST DEVICES

Background. Textured biomaterial surfaces in implantable left ventricu lar assist devices induce development of a nonthrombotic neointimal su rface and allow elimination of anticoagulation therapy in device recip ients. Characterization of the hematopoietic cells formed within the n eointimal surfaces of these devices will contribute to our understandi ng of this unique neointima. Methods. The blood-contacting surface of seven ThermoCardiosystems left ventricular assist devices was removed, washed with phosphate-buffered saline solution, and digested with 0.1 % collagenase for 15 to 20 minutes. The hematopoietic cells released f rom the explants were isolated and analyzed by now cytometry and immun ohistochemical staining. Results. More than 80% +/- 6% of hematopoieti c cells isolated in this fashion are of myelomonocytic origin and expr ess CD14, CD15, and CD33 surface molecules. Four percent of cells expr ess the CD34 surface marker, which suggests that the neointima is colo nized by pluripotent hematopoietic stem cells. Continuous culture of t hese hematopoietic cells in the presence of the cytokines interleukin- 3, c-kit ligand, granulocyte colony-stimulating factor, and granulocyt e/macrophage colony-stimulating factor resulted in tenfold expansion b y day 7 and 25-fold expansion by day 14. Conclusions. Pluripotent hema topoietic cells with a high proliferative capacity colonize textured s urfaces of left ventricular assist devices and may contribute to the d evelopment of a biologically nonthrombogenic neointima.