432 Artificial Organs 30(6):432–439, Blackwell Publishing, Inc. © 2006, Copyright the Authors Journal compilation © 2006, International Center for Artificial Organs and Transplantation Blackwell Publishing IncMalden, USAAORArtificial Organs0160-564X© 2006, Copyright the Authors; Journal compilation © 2006, International Center for Artificial Organs and Transplantation2006306432439Original Article HYDRODYNAMICS OF KANGAROO AORTIC VALVE MATRICESK.K. NARINE ET AL. Received October 2005; revised December 2005. Address correspondence and reprint requests to Dr. Kishan Narine, Department of Cardiac Surgery K12, 5Ve, University Hos- pital Gent, DePintelaan 185, B-9000 Ghent, Belgium. E-mail: kishan.narine@ugent.be Hydrodynamic Evaluation of Kangaroo Aortic Valve Matrices for Tissue Valve Engineering *Kishan K. Narine, †Katarzyna Kramm, †Kris Dumont, ‡Homayoun Jalali, ‡Lisa Sparks, †Patrick Segers, †Pascal Verdonck, and *Guido J. Van Nooten *Department of Cardiac Surgery, University Hospital Ghent; †Hydraulics Laboratory, Ghent University, Ghent, Belgium; and ‡Department of Cardiac Surgery, Prince Charles Hospital, University of Queensland, Brisbane, Queensland, Australia Abstract: We evaluated the hydrodynamic performance of kangaroo aortic valve matrices (KMs) (19, 21, and 23 mm), as potential scaffolds in tissue valve engineering using a pulsatile left heart model at low and high cardiac outputs (COs) and heart rates (HRs) of 60 and 90 beats/min. Data were measured in two samples of each type, pooled in two CO levels (2.1 ± 0.7 and 4.2 ± 0.6 L/min; mean ± standard errors on the mean), and analyzed using analysis of vari- ance with CO level, HR, and valve type as fixed factors and compared to similar porcine matrices (PMs). Transvalvular pressure gradient (∆P) was a function of HR (P < 0.001) and CO (P < 0.001) but not of valve type (P = 0.39). ∆P was consistently lower in KMs but not significantly different from PMs. The effective orifice area and performance index of kangaroo matrices was statistically larger for all sizes at both COs and HRs. Key Words: Kangaroo aor- tic valve matrices—Porcine aortic valve matrices—Hydro- dynamics of heart valve matrices—Tissue engineering. Currently, two types of prosthetic heart valves are available to cardiac surgeons, namely, bioprosthetic valves made from biological material and mechanical valves made from nonbiological material. Both types of devices are associated with significant limitations including a need for anticoagulation, infection, and degeneration (1–6). A tissue engineered living valve would replenish its extracellular matrix, avoid anticoagulation, and theoretically offer the possibility of growth after implantation. One approach to tissue valve engineering involves seeding living cells onto an acellular biological matrix in vitro in order to produce a living construct before implantation. Acellular porcine aortic valves have been used by several groups as a biological scaffold onto which autologous cells are seeded (7–11). Once implanted, the seeded cells are expected to replenish the matrix over time using the initial scaffold as a template. Kangaroos are upright and more similar in posture to humans compared to pigs. Their aortic valves are morphologically and histologically different from porcine aortic valves (12). In particular, kangaroo aortic valves have thinner leaflets with a more com- pact collagenous matrix compared to porcine aortic valves and unlike porcine aortic valves, have no mus- cular shelf in the right coronary cusp (12–14). Such a muscular shelf, in addition to possibly obstructing flow, also necessitates muscular decellularization when preparing acellular biological scaffolds. Its absence in the kangaroo valve avoids both possible obstruction with hydrodynamic consequences as well as the need for muscular decellularization. Indeed, Weinhold and coworkers, who implanted whole kan- garoo aortic valves in the tricuspid position of sheep, reported superior hemodynamic performance of kangaroo aortic valves compared to porcine ones (14). A major challenge in tissue valve engineering is sufficient and satisfactory invasion of scaffolds by the repopulating cells. Collagen is a proinvasive substrate for mesenchymal cells (15,16), and the compact collagenous matrix of kangaroo aortic valve leaflets could be an advantage in cellular repopula- tion while requiring fewer cell for total repopulation