Osteoclast Inhibition and Bone Formation

Effects of Age and Osteoclast Inhibition on Bone Formation

This protocol addresses: 1) How gene expression changes in bone cells are affected by aging? 2) Is aging associated with decreased signaling between bone cells? 3) How does treatment with the osteoporosis medication denosumab affect bone cell signaling?

This protocol collectively addresses the following goals: 1) What are the changes in gene expression in osteoblasts and osteocytes that lead to impaired bone formation with aging; 2) Since recent work from the investigators' group has demonstrated that osteoclasts produce a number of growth factors and cytokines (coupling factors) that enhance osteoblast proliferation and/or differentiation, is aging associated with reduced osteoclast coupling factor production; and 3) If osteoclasts are markedly reduced using the FDA-approved medication for osteoporosis, denosumab, how does that effect the quantity of coupling factors in the bone microenvironment and the target genes of these coupling factors in osteoblasts?

• Inclusion Criteria:

  • normal premenopausal women aged 25-40 years
  • normal postmenopausal women aged 60-80 years
  • at least 5 yrs since their last menses
  • follicle stimulating hormone (FSH) > 20 IU/L

• Exclusion Criteria:

  • Abnormality in any of the screening laboratory studies
  • Presence of significant liver or renal disease
  • Malignancy (including myeloma)
  • Malabsorption
  • Diabetes
  • Hypoparathyroidism
  • Hyperparathyroidism
  • Acromegaly
  • Cushing's syndrome
  • Hypopituitarism
  • Severe chronic obstructive pulmonary disease
  • Undergoing treatment with any medications that affect bone turnover, including the following:

• adrenocorticosteroids (> 3 months at any time or > 10 days within the previous yr)

• anticonvulsant therapy (within the previous year)

• pharmacological doses of thyroid hormone (causing decline of thyroid stimulating hormone below normal)

• calcium supplementation of > 1200 mg/d (within the preceding 3 months)

• bisphosphonates (within the past 3 yrs)

• denosumab

• estrogen (E) therapy within the past year

• treatment with a selective E receptor modulator within the past year

• teriparatide within the past yr

  • Clinical history of osteoporotic fracture (vertebral, hip, or distal forearm)
  • Recent (within the past 6 months) fracture
  • Serum 25-hydroxyvitamin D levels of < 20 ng/ml