Abstract
Human mesenchymal stem cells (hMSC), residing in the bone marrow, can be purified, expanded in cell culture and under appropriate stimuli may differentiate along the osteogenic, chondrogenic and adipogenic lineages. The aim of this study was to investigate the expansion capability and differentiation potential of MSCs obtained from femur, pelvis and acetabular cancellous bone of aged patients in order to establish whether these cells, isolated and expanded in vitro, can be used in a new approach in orthopaedic revision surgery.
In this preliminary study we enrolled 33 patients undergoing hip arthroplasty in order to investigate CFU-F frequency, expansion ability and differentiation potential of hMSC derived from three different anatomical sites: femural, pelvic and acetabular cancellous bone (ACB).
CFU-F frequency (CFU-F/10 6 MNC) was 63 for pelvis (range 7–122), 90 for bone (39–132) and 47.5 for femur (7–124).CFU-F frequency was higher in ACB than in either pelvis (p=0.04) or femur (p=0.001). The patients were divided into three age groups: G1 ≤50 years (n=6), G2 50 −65 years (n=11), and G3 ≥65 years (n=16); however, CFU-F frequency did not show any statistically significant difference, although the frequency was lower at higher age.
We expanded in cell culture MSC of 16 patients from the three considered sites until the fourth passage. At the first passage there was a higher MSC recovery in ACB (median 12%) than in pelvis (median 8%; p< 0.004) and femur (median 3.8%; p< 0.0004). MSC recovery from pelvis was higher than in femur (p< 0.04). At the second and third passage MSC expansion was found to be significantly higher in ACB than in pelvis alone (median 3.1 vs 1.6, p< 0.01; 1.8 vs 1.2, p< 0.005, respectively), while at the fourth passage it became higher than in pelvis and femur (median 2.6 vs 1.4, p< 0.03; 2.6 vs 1.6, p< 0.0, respectively). At each culture passage, cells showed MSC features as supported by flow cytometry and by the multilineage differentiation potential.
hMSCs seem to have higher frequency in close association with bone; moreover, they show an increased expansion ability in vitro which is still mantained in elderly patients. As these progenitors can differentiate in bone, they seem to be the best choice for the effective repair of bone defects in revision surgery.
