A comparison of mesenchymal precursor cells and amnion epithelial cells for enhancing cervical interbody fusion in an ovine model.

BACKGROUND: Rapid, reliable fusion is the goal in anterior cervical diskectomy and fusion. Iliac crest autograft has a high rate of donor-site morbidity. Alternatives such as bone graft substitutes lack osteoinductivity, and recombinant bone morphogenetic proteins risk life-threatening complications. Both allogeneic mesenchymal precursor cells (MPCs) and amnion derived epithelial cells (AECs) have osteogenic potential.
OBJECTIVE: To compare for the first time the capacity of MPCs and AECs to promote osteogenesis in an ovine model.
METHODS: Five groups of 2-year-old ewes were subjected to C3-4 anterior cervical diskectomy and fusion with a Fidji interbody cage packed with iliac crest autograft alone (group A; n = 6), hydroxyapatite-tricalcium phosphate Mastergraft granules (HA/TCP) alone (group B; n = 6), HA/TCP containing 5 million MPCs (group C; n = 6), or HA/TCP containing 5 million AECs (group D; n = 5); group E was made up of age-matched nonoperative controls (n = 6). At 3 months, animals were euthanized and quantitative multislice computed tomography, functional radiography, biomechanics, histology, and histomorphometry were performed.
RESULTS: No procedure- or cell-related adverse events were observed. There was significantly more fusion in the MPC group (C) than in group A, B, or D. Computed tomography scan at 3 months revealed that 5 of 6 MPC-treated animals (83%) had continuous bony bridging compared with 0 of 5 AEC-treated and only 1 of 6 autograft- and 2 of 6 HA/TCP-treated animals (P = .01).
CONCLUSION: Implantation of allogeneic MPCs in combination with HA/TCP within an interbody spacer facilitates interbody fusion after diskectomy. The earlier, more robust fusion observed with MPCs relative to autograft and HA/TCP bone substitute indicates that this approach may offer a therapeutic benefit.