Toward scaffold-based meniscus repair: effect of human serum, hyaluronic acid and TGF-ß3 on cell recruitment and re-differentiation.

OBJECTIVE: Repair approaches for the non-vascular meniscus are rarely developed. Recent strategies use scaffold-based techniques and inducing factors. The aim of the study was the investigation of cell recruitment and re-differentiation inducing factors for a scaffold-based meniscus repair approach. METHOD: 3D cultivation of in vitro expanded human meniscus-derived cells was performed in high-density cultures supplemented with 25% hyaluronic acid (HA), 10% human serum (HS) or 10 ng/ml transforming growth factor (TGF-ß3) compared to untreated controls. The in vitro cell recruitment potential of different HS concentrations was tested by chemotaxis assay. Analysis of chondrocytic markers (type I, II, IX collagen and proteoglycans) was performed on protein and gene expression level. RESULTS: Cells were attracted by 1-20% HS. 3D cultures supplemented with 10% HS and 25% HA showed meniscus-like gene expression profiles at day 7 with significantly increased cartilage oligomeric matrix protein (COMP) and aggrecan expression levels in the HS group and a slightly increased profile in the HA group compared to control. The TGF-ß3 group showed an additional induction of gene expression levels for type II and type IX collagen. Histological findings confirmed these results by proteoglycan and type I collagen staining in all groups and type II collagen staining only in the TGF-ß3 group. CONCLUSION: This study demonstrates that human meniscus cells are attracted by HS and allow for meniscal matrix formation in 3D culture in the presence of HA and HS, whereas TGF-ß3 additive does not initiate meniscal tissue. Regarding non-vascular meniscus repair, results of this study encourage scaffold-based repair approaches.

Antiviral effects of recombinant interferon alfa and clinical experience in viral infections.

Alpha interferons act virostatically by influencing several cellular enzymes involved in virus replication. The success of treatment with biosynthetic recombinant interferon alfa-2b (rIFN alfa-2b) has been confirmed in numerous clinical studies. Following intralesional injection, up to 56% of condylomata acuminata were totally eradicated. Laryngeal papillomatosis responded favourably to systemic therapy with various alpha-interferons, demonstrating complete remissions of up to 88%. Preliminary therapeutic trials using rIFN alfa-2b in chronic viral hepatitis (B, Delta, non-A, non-B) consistently showed beneficial effects on the disease-related biochemical, virological and histological parameters. Interferon alfa-2b proved particularly effective in the early stage of AIDS-associated Kaposi's sarcoma.

Large surface proteins of hepatitis B virus containing the pre-s sequence.

The sequence of hepatitis B virus DNA contains an open reading frame which codes for a not-yet-identified protein of at least 389 amino acids. Only the products starting at the third (GP33/GP36) or the fourth (P24/GP27) initiation signal have been characterized as components of the viral surface antigen. We found a larger protein, P39, and its glycosylated form, GP42, in hepatitis B virus particles and viral surface antigen filaments. Immunological cross-reactions showed that P39/GP42 is partially homologous to P24/GP27 and GP33/GP36. The unique portion of its sequence bound monoclonal antibodies which had been induced by immunization with hepatitis B virus particles. Proteolytic cleavage patterns and subtype-specific size differences suggested that the sequence of P39 starts with the first initiation signal of the open reading frame. Its amino-terminal part (pre-s coded) is exposed at the viral surface and, probably, is highly immunogenic. A model is presented of how the open reading frame for the viral envelope leads to defined amounts of three different proteins.

Specificity and localization of the hepatitis B virus-associated protein kinase.

The nature of the protein kinase (PK) which phosphorylates the core protein of hepatitis B virus in vitro was studied. The PK copurified with the core particles during rate zonal centrifugation and gel chromatography. It showed the same size heterogeneity as the core particles, which consisted of a main fraction of 28-nm particles and a subfraction of 22- to 26-nm particles. DNA-containing heavy core particles with a density of 1.33 to 1.35 g/ml and less endogenous PK than did the light cores. The phosphorylation reaction had a rapid initial phase (several minutes) and a slow but long-lasting second phase (many hours). The PK had a high affinity for ATP (KM = 0.5 mumol/liter). Only few of the several hundred P21.9 subunits in one core particle were phosphorylated in vitro. The only amino acid which was phosphorylated in vitro was serine. The resistance of the introduced phospho group against alkaline phosphatase showed that the PK acceptor, and probably the enzyme itself, was located inside the core particle.