Effects of chondroitin sulfate and interleukin-1 beta on human articular chondrocytes cultivated in clusters.

OBJECTIVE: To test the effects of chondroitin sulfate (ACS, a glycosaminoglycan of cartilage) with and without interleukin-1 beta (IL-1 beta) on human articular chondrocytes cultivated in clusters and in long-term (0-16 days or 16-32 days). DESIGN: Chondrocyte productions of proteoglycans (PGs), type II collagen (coll-II) and prostaglandin E2 (PGE2) were assayed by specific radioimmunoassays applied to conditioned culture media and to clusters. RESULTS: During the two culture periods (0-16 days or 16-32 days), ACS (100-1000 micrograms/ml) increased total PG production and had no effect on the production of coll-II by chondrocytes. During the first 16 days, ACS (500-1000 micrograms/ml) decreased total PGE2 synthesis. IL-1 beta decreased PG and coll-II productions and increased PGE2 synthesis. During the first period (0-16 days), while the cluster is forming, ACS counteracted the IL-1 beta-induced effects on PG (500-1000 micrograms ACS/ml), coll-II (100-1000 micrograms ACS/ml) and PGE2 (500-1000 micrograms ACS/ml) productions. During the second period (16-32 days), when the cluster is already formed, ACS counteracted the IL-1 beta-induced effects on total PG (100-1000 micrograms ACS/ml), coll-II (1000 micrograms ACS/ml) and PGE2 (1000 micrograms ACS/ml) productions. CONCLUSION: These in vitro studies suggest that ACS is able to increase matrix component production by human chondrocytes and to inhibit the negative effects of IL-1 beta.

Effects of ipriflavone and its metabolites on human articular chondrocytes cultivated in clusters.

Ipriflavone (IP) is an isoflavone derivative that was suggested to have bone-sparing effects in post-menopausal and senile osteoporosis. A moderate stimulatory effect of IP and its metabolites on proliferation of osteoblastic cells was reported in rat osteoblastic osteosarcoma cell line. We investigated the effects of different concentrations (0, 1, 10 and 100 micrograms/ml) of IP and its metabolites (MET I, II, III and V) on the incorporation of [3H] thymidine and production of proteoglycans (PG) and type II collagen (COL II) by human articular chondrocytes during a 12-day period, in a three-dimensional chondrocyte culture model. [3H]thymidine uptake was measured in chondrocyte clusters, and specific PG and COL II radioimmunoassays were performed every 4 days on the culture medium and cell clusters. Incubation with IP or its metabolites did not affect [3H]thymidine uptake regardless of the dose. PG released into the culture medium and PG cluster content rose significantly (P < 0.025) in presence of IP (1, 10 and 100 micrograms/ml). MET I increased PG release in culture medium (10 and 100 micrograms/ml) and PG cluster content (100 micrograms/ml). MET II has no effect on PG production. MET III increased PG in culture medium (100 microgram/ml) but did not influence PG cluster content while MET V (100 micrograms/ml) increased both PG release in culture medium and PG cluster content. COL II release in culture medium and COL II cluster content were significantly (P < 0.025) increased in presence of IP (10 and 100 micrograms/ml), MET III (1, 10 and 100 micrograms/ml) or MET V (100 micrograms/ml). MET I and II did not significantly affect COL II production.

Effects of tiaprofenic acid and acetylsalicylic acid on human articular chondrocytes in 3-dimensional culture.

Two nonsteroidal antiinflammatory drugs (NSAID: acetylsalicylic acid, ASA, and tiaprofenic acid, TA) were tested on differentiated human chondrocytes cultivated in clusters. DNA synthesis was depressed by ASA at therapeutic concentrations. The amount of proteoglycans in culture medium was decreased by ASA, whereas type II collagen was not modified. By contrast, TA did not affect chondroformative processes in chondrocytes. Both NSAID were potent inhibitors of prostaglandin E2 (PGE2) synthesis, TA being more efficient than ASA. From these experiments, we conclude that TA and ASA inhibit PGE2 synthesis; TA did not depress chondroformative variables in human cartilage in vitro, while ASA induced a decrease of DNA and proteoglycan syntheses.