Bone Abstracts

Objective: Endothelial progenitor cells (EPCs) have the potential ability to differentiate into vascular endothelial cells and osteoblasts for angiogenesis and osteogenesis, however, the correlation between number and population of bone marrow EPCs with bone mass and bone metabolism in elderly is unknown.

Methods: Trabecular bone were extracted from 11 patients with fragility fracture and eight patients with osteoarthritis during artificial hip replacement surgery, and EPCs separated from bone marrow were prepared for flow cytometry analysis. All the patients took DEXA scan, and bone metabolism detection. The impact of clinical data such as age, BMI, bone mass and bone metabolism markers on the number and population of bone marrow EPCs in the elderly were analyzed.

Results: There was no significant difference of age and BMI between fragility fracture patients and osteoarthritis patients. The total number of bone marrow EPCs and number of mature EPCs in fragility fracture patients were significantly less than that in osteoarthritis patients (0.48±0.35 vs 1.80±1.01, P=0.001; 52.28±21.20 vs 77.13±19.15, P=0.042), and the bone mass of femur neck and total hip (0.54±0.14 vs 0.76±0.21, P=0.021; 0.65±0.14 vs 0.84±0.15, P=0.026) as well as serum 25(OH)D level (4.50±1.56 vs 23.80±2.88, P=0.033) in fragility fracture patients were significantly lower than those in osteoarthritis patients, however serum PTH lever (73.60±1.84 vs 32.20±0.98, P=0.035) was significantly higher in fragility fracture patients than that in osteoarthritis patients. There are significantly negative correlation between age with number of mature EPCs (r=−0.594, P=0.015), and positive correlation between bone mass in femur neck and total hip with number of mature EPCs (r=0.847, P=0.008; r=0.925, P=0.034), and negative correlation between bone mass in total hip with number of premature EPCs (r=−0.817, P=0.047). However, BMI, 25(OH)D and PTH did not show any correlation with number of bone marrow EPCs.

Conclusion: Bone marrow EPCs could influence bone mass via regulating bone metabolism directly or indirectly in the elderly.