MRI of the proximal femur predicts marrow cellularity and the number of mesenchymal stem cells

Abstract

To determine whether the marrow conversion index (MCI) in MRI is related to the total number of mononuclear and mesenchymal stem cells (MSCs) in proximal femoral metaphysis of patients with hip osteoarthritis. Thirty-two hips of 32 consecutive patients who underwent total hip arthroplasty (THA) for hip osteoarthritis were included in this study. MRI of the hip was performed preoperatively and MCI was subsequently calculated. Three-milliliter bone marrow samples were obtained from the proximal femur during THA and the number of total mononuclear cells was determined using a hemocytometer. Colony forming unit-fibroblasts (CFU-Fs) assays of MSCs were performed by transferring a total of 2 × 10(4) mononuclear cells to each of five 60-mm plates. One week later, the numbers of colonies were counted. The total number of mononuclear cells decreased with increasing MCI. Likewise, the prevalence and total number of CFU-Fs increased with increasing number of total mononuclear cells, and decreased with increasing MCI. Our results suggest that measurement of MCI in MRI can be an objective and noninvasive method to predict marrow cellularity and the number of MSCs in patients with hip osteoarthritis.