Use of fluorescence labeled mesenchymal stem cells in pluronic F127 and porous hydroxyapatite as a bone substitute for posterolateral spinal fusion

Abstract

Posterolateral spinal fusion is used to treat patients with degenerative spinal disorders. We investigated the effectiveness of a mesenchymal stem cell (MSC)/Pluronic F127/Interpore hybrid graft for spinal fusion in rabbits. Spinal fusion was examined using radiography, manual palpation, computed tomography (CT), torsional loading tests, and histological analysis. Using a PKH fluorescence labeling system, we also examined whether the newly formed bone was derived from the transplanted MSCs. We found that the MSCs adhered to the Interpore surface and within its pores, and differentiated into osteoblasts. Radiographs and CT images showed a continuous bone bridge and a satisfactory fusion mass incorporated into the transverse processes. The results of manual palpation and biomechanical data did not differ significantly from an autograft group. Histology from both groups revealed the presence of fibrous tissue, cartilage, and endochondral ossification in the gaps between the grafted fragments. In both groups, the degree of mature bone formation was greater at 12 weeks than at 6 weeks after grafting. Quantitative histomorphometry revealed no significant differences between the two groups at either time point. In situ tracing of the PKH 67-labeled MSCs indicated that the transplanted MSCs were partly responsible for the new bone formation in both the repaired transverse processes and the grafted fragments. Thus, the MSC/Pluronic F127/Interpore hybrid graft could be used effectively to achieve posterolateral spinal fusion. ß

Factors influencing arthrodesis rates in a rabbit posterolateral spine model with iliac crest autograft

“…The aim of this study was to achieve a fusion rate of less than 40 % and then determine whether autologous bone marrow augmented arthrodesis. Other studies subsequently used this bone paucity model to provide a larger potential for improved fusion rates with a variety of bone graft substitutes [13][14][15][16][17][18][19][20][21][22]. While our study found a significant positive relationship between volume of autograft and fusion rates, a tenfold range of volume of autograft (1.4-12 cm 3 ) was used in the studies evaluated.…”

“…Chen et al [15] argued that the higher fusion rate seen in the younger rabbits utilized in their study might be attributed to a more vigorous healing response relative to older rabbits used in previous studies. Indeed, younger rabbits may have a higher capacity for spinal fusion since their skeletal systems are relatively immature, and ongoing bone remodeling could accelerate fusion.…”

“…Although there was no definitive association established between age or weight of rabbits and fusion rates, these variables have previously been suggested to affect arthrodesis [15]. Chen et al [15] argued that the higher fusion rate seen in the younger rabbits utilized in their study might be attributed to a more vigorous healing response relative to older rabbits used in previous studies.…”

Tissue Engineering Strategies in Spinal Arthrodesis: The Clinical Imperative and Challenges to Clinical Translation

“…In essence, the goal is to expand MSCs on tissue culture plastic prior to loading of the cell population onto a scaffold in order to increase osteoprogenitor cell numbers and to hopefully improve the chances of a successful fusion. A number of small and large animal studies have compared the effects of using scaffolds seeded with culture-expanded MSCs in a variety of spinal fusion models, although the results have proved somewhat mixed (Table 3) [60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78]. The discrepancy in findings could, in part, be explained by differences in culture expansion techniques used in the various studies.…”

Re: Bone marrow mesenchymal stem cells enhance bone formation in orthodontically expanded maxillae in rats. Abdullah Ekizer, Mehmet Emir Yalvac, Tancan Uysal, Mehmet Fatih Sonmez, Fikrettin Sahin. The Angle Orthodontist. Online Early

“…8 A critical variable in stem cell-based therapy is the number of cells used for implantation (10 7 - 10 8 ) in a suitable 3D graft, 8,9 but the treatment used by Eziker et al involved 10 6 MSCs/100 mL floating in a vehicle medium (sterile saline or PBS), without the presence of platelet-rich plasma, which has been shown to be able to regenerate functional bone in alveolar deficiencies. 10 We think that sound results are crucial in stem cell research and particularly important in order to avoid " dark stem cell therapy" in orthodontic patients.…”