Proteoglycans Synthesized by Human Chondrocytes Cultivated in Clusters

Proteoglycan metabolism was studied by a specific human cartilage proteoglycan radioimmunoassay in human chondrocytes cultivated in clusters. In this culture system, after a few days, previously dissociated chondrocytes were aggregated. They then synthesized a new cartilage matrix and were morphologically differentiated; they had a round shape and were situated inside small individual cavities (lacunae). The amounts of proteoglycan released into culture medium and present in chondrocyte clusters were maximal on the third to fifth day of culture; production decreased and stabilized from the 10th day to the end of culture. During the first days of culture, monomeric proteoglycans were present in large proportion; they gradually decreased between the sixth and 11th day of culture. These results suggest a modified synthesis of proteoglycan and hyaluronic acid during cultivation

Cytological and cytochemical analysis of the effects of cis-dichlorodiamino platinum (II) on chick fibroblasts cultivated in vitro.

Chick embryo fibroblasts cultivated in vitro and treated with cis-dichlorodiamino platinum (II) have been analysed by cytological and cytochemical methods. Morphological alterations (in the nucleoli, in the chromatin and in the cytoplasm), inhibition of DNA and RNA syntheses and of cell multiplication have been noted. Under some conditions, cells are blocked just before entering into mitosis (G2 block) and can become polyploid. A high degree of cell degeneration has also been observed

Effects of Peptidic Glycosaminoglycans Complex on Human Chondrocytes Cultivated in Three Dimensions

Human chondrocytes from the pelvic joint were cultivated in suspension; under these conditions, after a few days, cells aggregated. These chondrocytes were morphologically differentiated (round shape, situated inside cavities and surrounded by a matrix synthesized during cultivation) and biosynthetically differentiated (synthesis of type II collagen and cartilage proteoglycans (PG) (Bassleer et al. In vitro 22, 115-120, 1986). In this work, we present the metabolic and cellular effects of a peptidic-glycosaminoglycan (P-GAG) complex isolated from calf cartilage and bone marrow. We analyzed the effects of P-GAG on DNA synthesis (appreciated by 3H-thymidine incorporation into DNA), on type II collagen and on PG synthesis analyzed by specific radioimmunoassays. According to its final concentration in culture medium, P-GAG was able to stimulate proliferation or to favor the production of specific components of cartilage matrix, type II collagen and PG

Effects of Human and Salmon Calcitonin on Human Articular Chondrocytes Cultivated in Clusters

The effects of different pharmacological concentrations (0, 5, 10, 100, and 1000 ng/mL) of synthetic human calcitonin (hCT) and salmon calcitonin (sCT) on the incorporation of [3H]thymidine and production of proteoglycans (PG) and type II collagen (coll II) by human articular chondrocytes during a 20-day period were studied in a tridimensional chondrocyte culture model. [3H]Thymidine uptake was measured in chondrocyte clusters, and specific PG and coll II RIAs were performed every 4 days on the culture medium and cell aggregates; total PG and coll II production were also assessed at different culture durations by adding the amounts found in culture media and their corresponding clusters. Incubation with hCT or sCT did not affect [3H]thymidine uptake regardless of the dose. For each culture period, PG and coll II release into culture medium, cluster content, and total production increased significantly in a dose-dependent manner. Cumulative curves for these parameters showed a progressive significant increase with culture duration at hCT and sCT doses of 0, 5, and 10 ng/mL. Cumulative curves obtained with 10, 100, and 1000 ng/mL were seldom significantly different from one another. No differences emerged between the use of hCT or sCT. Thus, CT exerted no proliferative effect on human articular chondrocytes in tridimensional culture, but displayed a dose-dependent and prolonged stimulatory effect on PG and coll II production. CT may possess chondroprotective properties in addition to its other known effects

Synthesis and antimitotic effects of isoretulinal, a main alkaloid isolated from Strychnos variabilis

Isoretulinal is a new alkaloid isolated from Strychnos variabilis rootbark. It can also be easily prepared by oxydation of isoretuline. This alkaloid shows an antimitotic effect at a dose of 10 micrograms/ml on different strains of cancer cells. Moreover isoretulinal possesses an analgesic activity. However this alkaloid is sixty-fold less toxic than strychnine (intravenous acute toxicity in mice)