Differential modulation of growth and phenotypic expression of chondrocytes in sparse and confluent cultures by growth factors in cartilage.
The growth-promoting actions of cartilage extracts (CE) on rabbit cultured chondrocytes were studied to assess the role of local acting growth factors in the generation and expansion of highly differentiated cells. In the present study, DNA synthesis and proteoglycan synthesis in the cultured chondrocytes were monitored by flow cytofluorometry and double-isotope autoradiography by using [3H]thymidine and [35S]sulfate. We report here that actions of the same set of growth factors extracted from cartilage evokes differential cellular responses depending upon cell density. Growth factors in the optimal dose of CE (2 micrograms/ml) or epidermal growth factor (EGF, 40 ng/ml) did not reveal such a cell density-dependent effect on cellular proliferation. However, growth factors in CE induced proteoglycan synthesis selectively in nonproliferating and expressing cells in confluent culture.
Hiraki
Y
Y
Department of Biochemistry and Calcified Tissue Metabolism, Faculty of Dentistry, Osaka University, Japan.
Inoue
H
H
Asada
A
A
Suzuki
F
F
D000818:Animals; D001345:Autoradiography; D002356:Cartilage / Q000166:cytology / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005434:Flow Cytometry; D006133:Growth Substances / Q000502:physiology*; D008297:Male; D010641:Phenotype; D011509:Proteoglycans / Q000096:biosynthesis; D011817:Rabbits; D013462:Sulfur Radioisotopes; D014316:Tritium
D006133:Growth Substances; D011509:Proteoglycans; D013462:Sulfur Radioisotopes; D014316:Tritium; D004247:DNA