Abstract 2121: Customizing Future Tissue Engineered Heart Valves Through Phenotypic Modulation of Progenitor Cells
The optimal process for creating tissue engineered heart valves (TEHV) prior to clinical application remains incomplete. We investigated the effect of combination (MSCs and EPCs) and single cell sources (MSCs or EPCs) and two types of elastomeric scaffolds (non-woven poly-4-hydroxybutyrate [P4HB] and elastomeric poly(glycerol sebacate) [PGS]. Fibronectin-pre-coated P4HB and PGS (n=3; control= uncoated) were either single seeded or sequentially co-seeded with characterized ovine bone-marrow MSCs and peripheral blood-derived EPCs for 3 days followed by 18 days in a laminar fluid flow system. Independent of cell and polymer types, constructs exhibited increased cell growth (6.13×1011± 1.79×1011 p<0.001) versus initial cell densities. Independent of polymer types, sequential co-seeding illustrated an enhanced cellularity (62% and 13-fold) compared with single seeding and correlated with increases in percent positive area of valve ECM comparable to native pulmonary valve (PV) [laminin, collagen types (I/IV), tropoelastin, elastin, fibrillin, versican and chondroitin sulfate] except hyaluronic acid and heparin sulfate, which were increased in single seeded cells (measured by morphometry). Moreover, sequential co-seeding demonstrated significantly increased CD31+, vWF+ and VEGFR2+ cells comparable to native PV when compared with single seeded EPCs. Contrastingly, significant increased α-SMA+ cells were found in single seeded MSCs comparable to native valve when compared with sequential co-seeding. Independent of cell types, PGS demonstrated better organized tissue architecture, with uniform cellular arrangement and penetration into the “interstitium” versus P4HB. PGS demonstrated 1.5– 6x (p<0.05) the cell number as the P4HB except MSCs (6-fold p<0.05). However, P4HB revealed increased valve ECM compared to PGS. Mechanical tests of P4HB revealed increased percentage of elongation at break of co-seeded cells compared with single seeded MSCs and EPCs (72% and 17% respectively. Phenotypic modulation of progenitor cells could provide a conceptual framework for creating future TEHV based from elastomeric biomaterials and could potentially serve either as pulmonary valve leaflet or valved conduit.
This research has received full or partial funding support from the American Heart Association, Founders Affiliate (Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Vermont).