Cultured embryonic bone shafts show osteogenic responses to mechanical loading.
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.
Zaman
G
G
Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK.
Dallas
S L
SL
Lanyon
L E
LE
D000222:Adaptation, Physiological; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002642:Chick Embryo; D003094:Collagen / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009924:Organ Culture Techniques; D010006:Osteoblasts / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D013314:Stress, Mechanical; D013643:Tarsus, Animal / Q000196:embryology*; D013977:Tibia / Q000196:embryology*
D012333:RNA, Messenger; D003094:Collagen; D000469:Alkaline Phosphatase