Biomedical subjects

Jurg Grunenfelder

Publications and source records attributed to Jurg Grunenfelder.

3 recordsLinked to original sources

PubMed2005

Dynamic cine imaging of the mitral valve with 16-MDCT: a feasibility study.

OBJECTIVE: Our aim was to assess the feasibility and image quality of dynamic cine-mode imaging of the mitral valve using retrospectively ECG-gated 16-MDCT. SUBJECTS AND METHODS: Contrast-enhanced MDCT was performed in 37 patients who have a normal mitral valve, as shown on transesophageal echocardiography. Twenty CT data sets covering the valve apparatus were reconstructed every 5% step of the R-R interval. Multiplanar reconstructions were performed in the parallel short axis and perpendicular long axis of the left ventricle. Two independent blinded reviewers evaluated the image quality for dynamic cine-mode visualization of the valve components in systole and diastole and during the transitional phases in between. RESULTS: Interobserver agreement for image quality ratings of valve components in all cardiac cycle phases ranged from good to excellent. Image quality for the visualization of valve leaflets, apposition zone, commissures, and mitral annulus (ranging from adequate to excellent) was significantly superior on perpendicular plane images than on parallel plane images for all cardiac phases (p < 0.05). Tendinous cords were visualized on both perpendicular and parallel planes with bad to adequate quality, whereas visualization of the papillary muscles was adequate to excellent on both imaging planes. Visualization of each valve component was superior in systole and diastole in both imaging planes as compared with the transitional phases (p <0.001). CONCLUSION: Noninvasive cine-mode imaging of the mitral valve using retrospectively ECG-gated MDCT is feasible and allows accurate visualization of the moving valve. Perpendicular long-axis reconstructions yield images of superior quality when compared with the short-axis reconstructions and enable a determination of its functional morphology.

Aged↗

PubMed2002

Tissue engineering of functional trileaflet heart valves from human marrow stromal cells.

BACKGROUND: We previously demonstrated the successful tissue engineering and implantation of functioning autologous heart valves based on vascular-derived cells. Human marrow stromal cells (MSC) exhibit the potential to differentiate into multiple cell-lineages and can be easily obtained clinically. The feasibility of creating tissue engineered heart valves (TEHV) from MSC as an alternative cell source, and the impact of a biomimetic in vitro environment on tissue differentiation was investigated. METHODS AND RESULTS: Human MSC were isolated, expanded in culture, and characterized by flow-cytometry and immunohistochemistry. Trileaflet heart valves fabricated from rapidly bioabsorbable polymers were seeded with MSC and grown in vitro in a pulsatile-flow-bioreactor. Morphological characterization included histology and electron microscopy (EM). Extracellular matrix (ECM)-formation was analyzed by immunohistochemistry, ECM protein content (collagen, glycosaminoglycan) and cell proliferation (DNA) were biochemically quantified. Biomechanical evaluation was performed using Instron(TM). In all valves synchronous opening and closing was observed in the bioreactor. Flow-cytometry of MSC pre-seeding was positive for ASMA, vimentin, negative for CD 31, LDL, CD 14. Histology of the TEHV-leaflets demonstrated viable tissue and ECM formation. EM demonstrated cell elements typical of viable, secretionally active myofibroblasts (actin/myosin filaments, collagen fibrils, elastin) and confluent, homogenous tissue surfaces. Collagen types I, III, ASMA, and vimentin were detected in the TEHV-leaflets. Mechanical properties of the TEHV-leaflets were comparable to native tissue. CONCLUSION: Generation of functional TEHV from human MSC was feasible utilizing a biomimetic in vitro environment. The neo-tissue showed morphological features and mechanical properties of human native-heart-valve tissue. The human MSC demonstrated characteristics of myofibroblast differentiation.

Absorbable Implants↗

PubMed2002

A new source for cardiovascular tissue engineering: human bone marrow stromal cells.

OBJECTIVE: Vascular-derived cells represent an established cell source for tissue engineering of cardiovascular constructs. Previously, cell isolation was performed by harvesting of vascular structures prior to scaffold seeding. Marrow stromal cells (MSC) demonstrate the ability to differentiate into multiple mesenchymal cell lineages and would offer an alternative cell source for tissue engineering involving a less invasive harvesting technique. We studied the feasibility of using MSC as an alternative cell source for cardiovascular tissue engineering. METHODS: Human MSC were isolated from bone marrow and expanded in culture. Subsequently MSC were seeded on bioabsorbable polymers and grown in vitro. Cultivated cells and seeded polymers were studied for cell characterization and tissue formation including extracellular matrix production. Applied methods comprised flow cytometry, histology, immunohistochemistry, transmission (TEM) and scanning electron microscopy (SEM), and biochemical assays. RESULTS: Isolated MSC demonstrated fibroblast-like morphology. Phenotype analysis revealed positive signals for alpha-smooth muscle actin and vimentin. Histology and SEM of seeded polymers showed layered tissue formation. TEM demonstrated formation of extracellular matrix with deposition of collagen fibrils. Matrix protein analysis showed production of collagen I and III. In comparison to vascular-derived cell constructs quantitative analysis demonstrated comparable amounts of extracellular matrix proteins in the tissue engineered constructs. CONCLUSIONS: Isolated MSC demonstrated myofibroblast-like characteristics. Tissue formation on bioabsorbable scaffolds was feasible with extracellular matrix production comparable to vascular-cell derived tissue engineered constructs. It appears that MSC represent a promising cell source for cardiovascular tissue engineering.

Actins↗