Growth characterization of neo porcine cartilage pellets and their use in an interactive culture model.

Objective: The aim of this study was to evaluate the growth characteristics of freshly isolated porcine chondrocytes in high-density pellet cultures and to preliminary investigate their use in an interactive in vitro model with synovial fibroblast cell lines to study rheumatoid arthritis (RA).

Design: 1.8x10(6) chondrocytes/cm2 were seeded in 48-multiwell plates.

Re-endothelialization of punctured ePTFE graft: an in vitro study under pulsed perfusion conditions.

Background: When used as arteriovenous (AV) shunts for haemodialysis, small diameter expanded polytetrafluoroethylene (ePTFE) grafts have a high failure rate in vivo. Attempts to improve graft patency are various, and focus on either improvement of implantation techniques or graft tissue engineering. The tissue engineering approach attempts to reproduce in grafts the properties of pristine vasculature.

In a pig model ePTFE grafts will sustain for 6 weeks a confluent endothelial cell layer formed in vitro under shear stress conditions.

Objective: to investigate in a pig model whether small diameter ePTFE grafts will sustain a confluent endothelial cell layer formed in vitro under shear stress conditions.

Materials And Methods: thirteen ePTFE (4 mm) grafts were implanted end to end in the right femoral artery of; 8 grafts had been endothelialized in vitro. Grafts were left in situ for 6 weeks then evaluated with ultrasound and histology.

Cryopreservation of artificial cartilage: viability and functional examination after thawing.

In biomedical research and in reconstructive surgery, preservation of intact tissue has been an unsolved problem. In this study, we investigated the viability of cryopreserved artificial cartilage and its synthetic activity of cartilage-specific matrix proteins after thawing for in vitro use. A polymer fleece cylinder (diameter = 3 mm; height = 3 mm) was loaded with a suspension of bovine chondrocytes (25 x 10(6)/ml) and encapsulated with fibrin glue.

Endothelialization of PTFE vascular grafts under flow induces significant cell changes.

Background: To minimize thrombogeneity of small diameter PTFE grafts they are usually coated in vitro with endothelial cells under static culture conditions. The disadvantage of this technique is that a cell layer is formed that fails to withstand shear stress typical in normal blood flow.

Method: Since the in vivo functional and structural status of endothelial cells correlates with the applied shear stress, we developed a computer-controlled perfusion system to seed and culture cells on PTFE-grafts up to a confluent monolayer under the influence of increasing shear stress.