Nasal chondrocytes and fibrin sealant for cartilage tissue engineering.

Hybrid constructs associating a biodegradable matrix and autologous chondrocytes hold promise for the treatment of articular cartilage defects. In this context, our objective was to investigate the potential use of nasal chondrocytes associated with a fibrin sealant for the treatment of articular cartilage defects. The phenotype of primary nasal chondrocytes (NC) from human (HNC) and rabbit (RNC) origin were characterized by RT-PCR. The ability of constructs associating fibrin sealant and NC to form a cartilaginous tissue in vivo was investigated, firstly in a subcutaneous site in nude mice and secondly in an articular cartilage defect in rabbit. HNC express type II collagen and aggrecan, the two major hallmarks of a chondrocytic phenotype. Furthermore, when injected subcutaneously into nude mice within a fibrin sealant, these chondrocytes were able to form a cartilage-like tissue. Our data indicate that RNC also express type II collagen and aggrecan and maintained their phenotype in three-dimensional culture within a fibrin sealant. Moreover, treatment of rabbit articular cartilage defects with autologous RNC embedded in a fibrin sealant led to the formation of a hyalin-like repair tissue. The use of fibrin sealant containing hybrid autologous NC therefore appears as a promising approach for cell-based therapy of articular cartilage.

Antibody-based immunoadsorption as a therapeutic means.

Polyclonal antibodies against human low-density lipoprotein (LDL), covalently coupled to Sepharose CL-4B, are used to remove LDL from the plasma of familial hypercholesterolemic patients. During a single treatment LDL-cholesterol is lowered by more than 60%, and plasma viscosity is decreased by 10%. The usual treatment frequency is once a week. The possible development of human antisheep antibodies was followed for up to 5 years. The ELISA signal rose slightly above baseline reaching a plateau within the first year. Clinically, there have been no signs of column-related adverse reactions. Due to the versatility of immunoapheresis it is also applicable to deplete IgG by coupling antihuman IgG antibodies. These columns might be indicated for patients with high panel reactivity to enable organ transplantation and for patients with autoimmune disease. In vitro tests with plasma from high-panel-reactive dialysis patients have shown that IgG could be depleted by 95% across all subclasses and that panel reactivity could be reduced from 91 to 25%.

Principles of immunapheresis and specific elimination of plasma components.

In summary the therapeutic use of affinity chromatography, the immunapheresis with LDL-Therasorb columns, Baxter, has been shown to be a safe, specific and efficacious extracorporeal treatment. Following GMP rules LDL-Therasorb is produced in a constant quality. Beyond the treatment of hypercholesterolemia the versatility of antibodies opens this technology to the treatment of other diseases.

Thrombomodulin activity is found in tissue thromboplastin preparations from placenta and from lung but not from brain.

Substantial thrombomodulin activity could be detected in tissue thromboplastin preparations from placenta or from lung but not from brain. When the amount of these preparations was adjusted to contain 1 unit of tissue factor activity, up to 0.85 units of thrombomodulin activity could be measured, corresponding to the generation of 17 pmol/ml/min of activated protein C when 1.5 microM human protein C was activated by 20 nM human alpha-thrombin in the presence of 5 mM CaCl2. After treatment by phospholipase C, thrombomodulin activity was reduced in these samples. Addition of mixed brain procoagulant phospholipids partially restored thrombomodulin activity in the phospholipase C-treated samples. These results emphasize the role of phospholipids in the expression of optimal thrombomodulin activity in tissue thromboplastin preparations from placenta or from lung.