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These results are a first step to demonstrate that seeding of human fibroblasts and endothelial cells on PGA-mesh might be a feasible model to construct human tissues such as vessels or cardiac valves.

The macrophage cell line J774, primary rat osteoblasts, and the osteoblast cell line MC3T3-E1 were used to examine the biocompatibility of a newly developed polyesterurethane foam and the possible use of this structure as bone-repair materials. The newly developed, biodegradable, and highly porous (pore size 100-150 microns) DegraPol/btc polyesterurethane foam was found to exhibit good cell compatibility; the cell-to-substrate interactions induced neither cytotoxic effects nor activation of macrophages. Osteoblasts and macrophages exhibited normal cell morphology. No signs of cell damage were detected using scanning electron microscopy (SEM). No significant increase in the production of tumor necrosis factor-alpha (TNF-alpha) or nitric oxide (NO) was detected in macrophages. Compared with cells cultured on tissue culture polystyrene (TCPS), macrophages exhibited relatively high cell attachment (150% of TCPS) but significantly high doubling time (about 8 days) compared with TCPS (4.6 days). Primary rat osteoblasts and the osteoblast cell line exhibited relatively high attachment (140% and 180% of TCPS, respectively) and a doubling time of about 5 days, compared with TCPS (6 days and 8.8 days, respectively). Eight days after cell seeding, osteoblasts exhibited a confluent cell multilayer and migrated into the pores of the polymer. In addition they produced high concentrations of collagen type I, the main protein of the bone, and expressed increasing alkaline phosphatase activity and osteocalcin production throughout the 12 days of the experiment. During degradation of these polymers, small crystalline particles of short-chain poly[(R)-3-hydroxybutyric acid] (M(n) approximately 2300) (PHB-P) are released. Therefore PHB-P (diameter, 2-20 microns), as possible degradation products of the polymer, are investigated here for their effects on macrophages and osteoblasts. Results obtained in the present study clearly indicate that macrophages and, to a lesser degree, osteoblasts have the ability to take up (phagocytose) PHB-P. At low concentrations particles of PHB failed to induce cytotoxic effects or to activate macrophages. Osteoblasts showed only limited PHB-P phagocytosis and no signs of cellular damage. At high concentrations of PHB-P, this process was accompanied by cytotoxic effects in macrophages (> 200 pg PHB-P/cell) and to a lesser extent in osteoblasts (> 400 pg PHB-P/cell).

With use of an open 1.5-T magnetic resonance (MR) imager and a tracking catheter, the authors successfully placed the catheter into the left or right sacral artery in pigs. The tracking catheter comprised a 5.3-F percutaneous transluminal angioplasty catheter with a small copper radio-frequency coil in its tip. With use of the coil as an antenna, the catheter tip position was projected in real time onto MR angiography road maps in two planes. Guidance of placement of the catheter with the MR angiography road maps allowed successful embolization, balloon occlusion, and transjugular intrahepatic puncture of the portal system. Specialized catheters can be tracked in vivo to allow MR guidance in intravascular interventional procedures.

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