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Influence of experimental diabetes and insulin on matrix-induced cartilage and bone differentiation
Abstract:
The influence of streptozotocin-induced diabetes on discrete stages of matrix-induced endochondral bone formation has been investigated. Mesenchymal cell proliferation was inhibited in diabetic rats as evidenced by a 65% reduction of ornithine decarboxylase (ODC) activity and a 56% reduction of [3H]thymidine incorporation per microgram DNA compared to nondiabetic controls; the inhibition was prevented by insulin treatment. In diabetic animals, chondrogenesis on day 7 was reduced by 49% compared to control animals as assessed by 35SO4 incorporation. Exogenous insulin was stimulatory to cartilage development when present during days 0 through 4 (mesenchymal cell proliferation). Calcification of cartilage and osteogenesis were reduced by more than 50% in diabetic rats and corrected by insulin as measured by alkaline phosphatase activity and 45Ca incorporation. Decreased in vivo endochondral bone growth and development during diabetes is the result of 1) inhibition of insulin-dependent mesenchymal cell proliferation, 2) decreased and delayed cartilage formation due to impaired mesenchymal cell proliferation, 3) decreased and delayed vascular invasion prior to chondrolysis and osteogenesis, and 4) reduced insulin-dependent calcification and ossification.
Insights
Diabetes significantly impairs endochondral bone formation by inhibiting mesenchymal cell proliferation and cartilage development. Insulin therapy effectively reverses these detrimental effects on bone growth.
Area of Science:
- Biomedical Engineering
- Developmental Biology
- Metabolic Diseases
Background:
- Diabetes mellitus is a metabolic disorder with systemic effects.
- Endochondral ossification is a complex biological process crucial for bone development.
- Streptozotocin is a commonly used agent to induce diabetes in animal models.
Purpose of the Study:
- To investigate the impact of streptozotocin-induced diabetes on matrix-induced endochondral bone formation.
- To elucidate the specific stages of bone formation affected by diabetes.
- To evaluate the potential of insulin treatment to ameliorate these effects.
Main Methods:
- Streptozotocin was administered to induce diabetes in rats.
- Matrix-induced endochondral bone formation was studied at discrete stages.
- Key markers of cell proliferation (ornithine decarboxylase activity, [3H]thymidine incorporation), chondrogenesis (35SO4 incorporation), and osteogenesis (alkaline phosphatase activity, 45Ca incorporation) were measured.
- The effects of exogenous insulin administration were assessed.
Main Results:
- Diabetes significantly reduced mesenchymal cell proliferation (ODC activity, [3H]thymidine incorporation) and chondrogenesis (35SO4 incorporation).
- Calcification and osteogenesis were also markedly decreased in diabetic rats (alkaline phosphatase, 45Ca incorporation).
- Insulin treatment prevented or corrected the diabetes-induced impairments in all measured stages of bone formation.
Conclusions:
- Streptozotocin-induced diabetes profoundly inhibits multiple stages of endochondral bone formation.
- Key affected processes include insulin-dependent mesenchymal cell proliferation, chondrogenesis, vascularization, calcification, and ossification.
- Insulin therapy demonstrates a significant corrective effect on diabetes-related deficits in bone development.