Abstract
Activin A, a member of the TGF-β super-family, is abundant in bone matrix, but little is known about its physiological role in bone metabolism. The present study was undertaken to determine whether topical activin A can increase the bone mass of isografted bone. The tibiae were bilaterally dissected from a donor C3H/HeJ mouse and transplanted subcutaneously in the dorsal region of a recipient mouse. One isografted tibia was topically infused for either 1, 2, 3, or 4 weeks with activin A, using an osmotic minipump at a dose of 0.02, 0.2, or 2 ng/hr. The other tibia was infused with 0.9% NaCl (control). The following results were obtained: (1) Topical activin A (2 ng/hr) stimulated periosteal bone formation after 2 or 3 weeks. The bone area in a standardized transverse section averaged 1.3 fold that in the control. (2) Numerous cuboidal or conical osteoblasts appeared on the surface of newly formed bone after the infusion of activin A for 2 or 3 weeks. Autoradiographic studies using 3H-proline revealed that the surface area of newly formed bone labelled with autoradiographic silver grains was greater in activin A-treated bone than in the control, suggesting an increased synthesis and secretion of collagen by osteoblasts. (3) Topical activin A increased the number of osteoclasts after 2 to 4 weeks. Furthermore, enhanced or increased bone resorption was observed in the projected anterior site of activin A-treated bone after 4 weeks. These results suggest that topical activin A increases the bone mass of isografted bone by increasing bone turnover.
Original language | English |
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Pages (from-to) | 330-338 |
Number of pages | 9 |
Journal | Calcified Tissue International |
Volume | 70 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2002 Apr 1 |
Keywords
- Activin A
- Bone formation
- Isografting
- Osteoblast
- Osteoclast
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Orthopedics and Sports Medicine
- Endocrinology