Osteogenic Potential of Adult Human Stem Cells of the Lumbar Vertebral Body and the Iliac Crest

Study Design. Marrow was aspirated from the vertebral body (VB) and iliac crest (IC) of patients undergoing lumbar spinal surgery, following an approved protocol. Progenitor cells were isolated using standard culture conditions and their osteogenic potential evaluated. Objective. To evaluate the osteogenic potential of mesenchymal stem cells (MSCs) isolated from the bone marrow of the human VB. Summary of Background Data. IC marrow grafting during cervical discectomy and fusion procedure is associated with donor site morbidity. Since the VB contains marrow cells, it may be possible to circumvent this problem by using this tissue for osseous graft supplementation. However, there is paucity of information concerning the osteogenic potential of non-IC-derived progenitor cells. Herein, we address this issue. Methods. Marrow samples from VB of patients undergoing lumbar spinal surgery were collected; marrow was also harvested from the IC. Progenitor cells were isolated and the number of colony forming unit-fibroblastic (CFU-F) determined. The osteogenic potential of the cells was characterized using biochemical and molecular biology techniques. Results. Both the VB and IC marrow generated small, medium, and large sized CFU-F. Higher numbers of CFU-F were obtained from the VB marrow than the IC (P < 0.05). Progenitor cells from both anatomic sites expressed comparable levels of CD166, CD105, CD49a, and CD63. Moreover, progenitor cells from the VB exhibited an increased level of alkaline phosphatase activity. MSCs of the VB and the IC displayed similar levels of expression of Runx-2, collagen Type I, CD44, ALCAM, and ostecalcin. The level of expression of bone sialoprotein was higher in MSC from the IC than the VB. VB and IC cells mineralized their extracellular matrix to a similar extent. Conclusions. Our studies show that CFU-F frequency is higher in the marrow of the VB than the IC. Progenitor cells isolated from both sites respond in a similar manner to an osteogenic stimulus and express common immunophenotypes. Based on these findings, we propose that progenitor cells from the lumbar vertebral marrow would be suitable candidate for osseous graft supplementation in spinal fusion procedures. Studies must now be conducted using animal models to ascertain if cells of the VB are as effective as those of the IC for the fusion applications.