Cultured embryonic bone shafts show osteogenic responses to mechanical loading

• Published in: Calcified tissue international 1992-08, Vol.51 (2), p.132-136
• Main Authors: ZAMAN, G, DALLAS, S. L, LANYON, L. E
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Alkaline Phosphatase - metabolism; Animals; Biological and medical sciences; Cell differentiation, maturation, development, hematopoiesis; Cell physiology; Chick Embryo; Collagen - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Models, Biological; Molecular and cellular biology; Organ Culture Techniques; Osteoblasts - metabolism; RNA, Messenger - analysis; RNA, Messenger - metabolism; Stress, Mechanical; Tarsus, Animal - embryology; Tibia - embryology
• ISSN: 0171-967X; 1432-0827
• DOI: 10.1007/BF00298501

Pairs of 17-day embryonic chick tibiotarsi were removed and maintained in organ culture. One of each pair was subjected to a single 20-minute period of intermittent loading at 0.4 Hz, producing peak longitudinal compressive strains of 650 microstrain (mu epsilon). In the 18-hour culture period following loading, alkaline phosphatase levels in the osteoblasts of the loaded tibiotarsi were maintained whereas in controls they declined. In situ hybridization using a collagen type I cRNA riboprobe showed a substantial increase in expression of mRNA for collagen type I in the periosteal tissue of bones that were cultured for 18 hours after loading compared with that in similarly cultured controls and bones cultured for 4 hours. These results demonstrate that appropriate loading of embryonic chick bones in organ culture elicits adaptive regulation of matrix synthesis as evidenced by increased expression of the gene for type I collagen and alkaline phosphatase activity. This model may be useful as it must contain all the obligatory steps between strain change in the matrix and modified osteogenic activity.