Tobias Schilling

Tissue engineering of heart valves – human endothelial cell seeding of detergent acellularized porcine valves

OBJECTIVEnTissue engineering of heart valves represents a new experimental concept to improve current modes of therapy in valvular heart disease. Drawbacks of glutaraldehyde fixed tissue valves or mechanical valves include the short durability or the need for life-long anticoagulation, respectively. Both have in common the inability to grow, which makes valvular heart disease especially problematic in children. The aim of this study was to develop a new methodology for a tissue engineered heart valve combining human cells and a xenogenic acellularized matrix.nnnMETHODSnPorcine aortic valves were acellularized by deterging cell extraction using Triton without tanning. Endothelial cells were isolated in parallel from human saphenous veins and expanded in vitro. Specimens of the surface of the acellular matrix were seeded with endothelial cells. Analysis of acellularity was performed by light microscopy and scanning electron microscopy. Cell viability following seeding was assayed by fluorescence staining of viable cells.nnnRESULTSnThe acellularization procedure resulted in an almost complete removal of the original cells while the 3D matrix was loosened at interfibrillar zones. However the 3D arrangement of the matrix fibers was grossly maintained. The porcine matrix could be seeded with in vitro expanded human endothelial cells and was maintained in culture for up to 3 days to document the formation of confluent cultures.nnnCONCLUSIONSnPorcine aortic valves can be almost completely acellularized by a non-tanning detergent extraction procedure. The xenogenic matrix was reseeded with human endothelial cells. This approach may eventually lead to the engineering of tissue heart valves repopulated with the patients own autologous cells.

Surgical site infections—economic consequences for the health care system

PurposesUnfortunately, surgical site infections (SSIs) are a quite common complication and represent one of the major causes of postoperative morbidity and mortality, and may furthermore lead to enormous additional costs for hospitals and health care systems.MethodsIn order to determine the estimated costs due to SSIs, a MEDLINE search was performed to identify articles that provide data on economic aspects of SSIs and compared to findings from a matched case-control study on costs of SSIs after coronary bypass grafting (CABG) in a German tertiary care university hospital.ResultsA total of 14 studies on costs were found. The additional costs of SSI vary between

Heart valve and myocardial tissue engineering

3,859 (mean) and

In vivo degradation of magnesium alloy LA63 scaffolds for temporary stabilization of biological myocardial grafts in a swine model

40,559 (median). Median costs of a single CABG case in the recently published study were

Geometric adaption of biodegradable magnesium alloy scaffolds to stabilise biological myocardial grafts. Part I

49,449 (€36,261) vs.

Influence of Shot Peening on Surface Roughness and Invitro Load Cycles of Magnesium Alloys

18,218 (€13,356) in controls lacking infection (pu2009<u20090.0001). The median reimbursement from health care insurance companies was

Finite element simulation of myocardial stabilising structures and development of new designs.

36,962 (€27,107) leading to a financial loss of

Development of Magnesium Alloy Scaffolds to Support Biological Myocardial Grafts: A Finite Element Investigation

12,482 (€9,154) each.ConclusionCosts of SSIs may almost triple the individual overall health care costs and those additional charges may not be sufficiently covered. Appropriate measures to reduce SSI rates must be taken to improve the patient’s safety. This should also diminish costs for health care systems which benefits the entire community.

Geometric adaption of resorbable myocardial stabilizing structures based on the magnesium alloys LA63 and ZEK100 for the support of myocardial grafts on the left ventricle

Cardiac function, including the heart muscle and valves, can be severely altered by congenital and acquired heart diseases. Several graft materials are currently used to replace diseased cardiac tissue and valvular segments. Implantable grafts are either non-vital or can trigger an immune response which leads to graft calcification and degeneration. None of the existing grafts have the ability to remodel and grow in tandem with the physiological growth of a child and therefore require re-operation. Novel approaches such as tissue engineering have emerged as possible alternatives for cardiac reconstruction. The main concept of tissue engineering includes the use of biological and artificial scaffolds that form the shape of the organ structures for subsequent tissue replacement, which will provide absolute biocompatibility, no thrombogenicity, no teratogenicity, long-term durability and growth.Heart valve tissue engineering represents an important field especially in pediatric patients with valve pathologies. In order to create an autologous valve equivalent myofibroblasts and/or endothelial cells are seeded on specially designed scaffolds. Here we describe the different types of cell sources and different types of matrices currently used in heart valve tissue engineering. Valve manufacture is carried out in specially designed bioreactors providing physiological conditions. The number of clinical studies using tissue engineered valves is still limited; however, several promising results have already demonstrated their durability and ability to grow.Myocardial tissue engineering aims to repair, replace and regenerate damaged cardiac tissue using tissue constructs created ex vivo. Conceivable indications for clinical application of tissue engineered myocardial-implant substitutes include ischemic cardiomyopathies, as well as right ventricular outflow tract reconstruction in patients with congenital heart diseases. Therapeutic application of functional (contractile) tissue engineered heart muscle appears feasible once key issues such as identification of the suitable human cell source, large scale expansion and suitable scaffolds are solved. In addition, the present article discusses the importance of vascularization as an important prerequisite for successful bio-artificial myocardial tissue.Further experimental and clinical research on cardiovascular tissue engineering is felt to be of great importance for others as well as for us in order to create an ideal heart valve/myocardial substitute and help our patients with advanced cardiac pathologies.

Cardiovascular Applications of Magnesium Alloys

Abstract Synthetic or biological patch materials used for surgical myocardial reconstruction are often fragile. Therefore, a transient support by degradable magnesium scaffolds can reduce the risk of dilation or rupture of the patch until physiological remodeling has led to a sufficient mechanical durability. However, there is evidence that magnesium implants can influence the growth and physiological behavior of the host’s cells and tissue. Hence, we epicardially implanted scaffolds of the magnesium fluoride-coated magnesium alloy LA63 in a swine model to assess biocompatibility and degradation kinetics. Chemical analysis of the pigs’ organs revealed no toxic accumulation of magnesium ions in the skeletal muscle, myocardium, liver, kidney, and bone of the pigs 1, 3, and 6 months postimplantation. The implants were surrounded by a fibrous granulation tissue, but no signs of necrosis were histologically evaluable. A sufficiently slow degradation rate of the magnesium alloy scaffold can be demonstrated via micro-computed tomography investigation. We conclude that stabilizing scaffolds of the magnesium fluoride-coated magnesium alloy LA63 can be used for epicardial application because no significant adverse effects to myocardial tissue were noted. Thus, degradable stabilizing scaffolds of this magnesium alloy with a slow degradation rate can extend the indication of innovative biological and synthetic patch materials.