Digital measurements: a different approach to evaluate bone formation. A technical report

Effect of strontium substituted ß-TCP associated to mesenchymal stem cells from bone marrow and adipose tissue on spinal fusion in healthy and ovariectomized rat

Despite alternatives to autogenous bone graft for spinal fusion have been investigated, it has been shown that osteoconductive materials alone do not give a rate of fusion comparable with autogenous bone. This study analyzed a strontium substituted ß-tricalcium phosphate (Sr-ßTCP) associated with syngeneic, unexpanded, and undifferentiated mesenchymal stem cells from bone marrow (BMSC) or adipose tissue (ADSC) as a new tissue engineering approach for spinal fusion procedures. A posterolateral fusion was performed in 15 ovariectomized (OVX) and 15 sham-operated (SHAM) Inbred rats. Both SHAM and OVX animals were divided into three groups: Sr-ßTCP, Sr-ßTCP + BMCSs, and Sr-ßTCP + ADSCs. Animals were euthanized 8 weeks after surgery and the spines evaluated by manual palpation, micro-CT, and histology. For both SHAM and OVX animals, the fusion tissue in the Sr-ßTCP + BMSCs group was more solid. This effect was significantly higher in OVX animals by comparing the Sr-ßTCP + BMCSs group with Sr-ßTCP + ADSCs. Radiographical score, based on micro-CT 2D image, highlighted that the Sr-ßTCP + BMCSs group presented a similar fusion to Sr-ßTCP and higher than Sr-ßTCP + ADSCs in both SHAM and OVX animals. Micro-CT 3D parameters did not show significant differences among groups. Histological score showed significantly higher fusion in Sr-ßTCP + BMSCs group than Sr-ßTCP and Sr-ßTCP + ADSCs, for both SHAM and OVX animals. In conclusion, our results suggest that addition of BMSCs to a Sr-ßTCP improve bone formation and fusion, both in osteoporotic and nonosteoporotic animal, whereas spinal fusion is not enhanced in rats treated with Sr-ßTCP + ADSCs. Thus, for conducting cells therapy in spinal surgery BMSCs still seems to be a better choice compared with ADSCs.

Effects of Strontium Ranelate on Spinal Interbody Fusion Surgery in an Osteoporotic Rat Model

Osteoporosis is a bone disease that afflicts millions of people around the world, and a variety of spinal integrity issues, such as degenerative spinal stenosis and spondylolisthesis, are frequently concomitant with osteoporosis and are sometimes treated with spinal interbody fusion surgery. Previous studies have demonstrated the efficacy of strontium ranelate (SrR) treatment of osteoporosis in improving bone strength, promoting bone remodeling, and reducing the risk of fractures, but its effects on interbody fusion surgery have not been adequately investigated. SrR-treated rats subjected to interbody fusion surgery exhibited significantly higher lumbar vertebral bone mineral density after 12 weeks of treatment than rats subjected to the same surgery but not treated with SrR. Furthermore, histological and radiographic assessments showed that a greater amount of newly formed bone tissue was present and that better fusion union occurred in the SrR-treated rats than in the untreated rats. Taken together, these results show significant differences in bone mineral density, PINP level, histological score, SrR content and mechanical testing, which demonstrate a relatively moderate effect of SrR treatment on bone strength and remodeling in the specific context of recovery after an interbody fusion surgery, and suggest the potential of SrR treatment as an effective adjunct to spinal interbody fusion surgery for human patients.

Histomorphometry of the ligaments using a generic-purpose image processing software, a new strategy for semi-automatized measurements

Gold chloride technique can be combined with Adobe Photoshop® software to yield a quantitative assessment of the different areas in heterogeneous structures as are ligament. A semi-automatized method based on the sum of two- and three-dimensional morphological criteria upon colorimetric criteria allows the identification and measurement of the area occupied by a structure of interest. It also allows the quantification of color intensity to differentiate structures with similar staining avidity, like vessels and nerves. This computer-assisted, semiquantitative procedure for computerized morphometry is relatively simple to perform. The accuracy, efficiency, and reproducibility of this method based on a commercially available imaging program were considered adequate when tested on the anterior cruciate ligament of the cat. Image normalization by trained observers using a commercially available software package designed for photography, applied to a sample randomly chosen, has provided the means of making reproducible measurements of heterogeneous structures.