[Improvement of the amplification rate of human chondrocytes with IGF-I and RGD].

Human chondrocytes were incubated under following conditions: Group 1 (control group): Incubation in 25 cm2 cell culture flasks (Costar) with RPMI-medium (6%-AB-serum, L-Glutamin, Hepes-buffer and antibiotics); Group 2: Different concentrations of IGF-I (1 ng/ml, 10 ng/ml) were added to the RPMI-medium; Group 3: Incubation (like control group) with additional coating of the cell culture flasks with different concentrations of RGD (5 mg/ml; 7.5 mg/ml; 10 mg/ml; 20 mg/ml); Group 4: Combination of coating with RGD (5 mg/ml; 10 mg/ml) and addition of IGF-I (1 ng/ml; 10 ng/ml) to the medium. The cells of the control group could be doubled within 2 weeks. The amplification rate of the groups 2 and 3 was improved in comparison to group 1 with the following maxima: Group 2 (5 mg/ml RGD) 3.1 times and group 3 (1 ng/ml IGF-I) 2.6 times of the number of the cells in the beginning. Group 4 (RGD and IGF-I) showed additive effects, for 4.1 times of the number of the cells in the beginning could be counted after 14 days. RGD and IGF-I (groups 2 to 4) made possible an earlier dedifferentiation and adhesion of the cells to the bottom of the cell culture flasks. By using both growth factors (RGD and IGF-I), the number of the cells could be enhanced more than 2 times in comparison to the control group within the same time. So less than half of the autologous patient's cartilage is necessary for cultivation of hyaline cartilagee.