[Fibronectin osteogenic phenotypical expression by fibroblasts in vitro].
OBJECTIVE
To explore the regulator factor of osteogenesis induced by the fibroblast in vitro so as to provide enough seeding cells for the bone tissue engineering.


METHODS
The fibroblasts were isolated and purified from granulation of New Zealand rabbits, and they were incubated in the media of fibronectin (FN) 10, 20, 40, 60 and 80 microg/ml, respectively, in the experimental groups 1 - 5, but there was no FN in the control group. The markers for osteogenic features were investigated by fibroblast morphogenesis, calcium nodules formation ratios, labeling of tetracycline fluorescence, labeling of 3H-TdR, determination of osteocalcin, and labeling of 3H-proline within 2 weeks.


RESULTS
The morphological changes of the fibroblasts were manifested as transference from a long spindle to a round or multiple form, shifted nucleus increased in number, confluence and formed multilayered structure. There was a piling-up of calcium crystals that were gradually merged into foggy substances. The foggy substances increased and formed nodules. The calcium nodules formation ratios were as follows: 15.35% +/- 3.45% in the control group, and 53.73% +/- 9.49%, 75.21% +/- 9.80%, 98.34% +/- 15.20%, 61.83% +/- 10.04%, and 45.11% +/- 8.70% in the experimental groups 1-5, respectively. There was a significant difference between the control group and the 5 experimental groups at 14 days (P < 0.05), and a significant difference between the experimental group 3 and the other experimental groups at 14 days (P < 0.05). The histochemical study on the nodules with the specific labeling of tetracycline fluorescence indicated that the nodules were composed of new bones.


CONCLUSIONS
Fibronectin can stimulate the fibroblast to proliferate, secrete osteocalcin, and synthesize collagen fibrils. Fibronectin, in an optimal dose of 40-60 microg/ml, is capable of inducing the fibroblast to form the bone.
Li
Xiulan
X
Tianjin Institute of Orthopedics, Tianjin, P.R. China. zhengtg@eyou.com
Zhang
Yang
Y
Shi
Yijian
Y
Wang
Zengli
Z
D000818:Animals; D052005:Bone Morphogenetic Protein Receptors, Type I / Q000096:biosynthesis; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D005353:Fibronectins / Q000494:pharmacology*; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis; D010641:Phenotype; D011817:Rabbits; D023822:Tissue Engineering
D017077:Culture Media, Conditioned; D005353:Fibronectins; D015675:Osteocalcin; D052005:Bone Morphogenetic Protein Receptors, Type I