Combined with BMP, Adipose-Derived Stem Cells Promote Spinal Fusion in Animal Model
BY LAUREN UZDIENSKI, JUNE 4, 2008
A recent study published in JBJS shows some of the potential of adipose-dervived stem cells as a vehicle for gene therapy in promoting spinal fusion. Five groups of rats received stem cells and the BMP gene, stem cells, osteogenic media and recombinant BMP, recombinant BMP alone or stem cells alone, as described below, with the intent of promoting fusion in L4-L5:
Group I was treated with adipose-derived stem cells transduced with an adenoviral vector containing the BMP-2 gene.
Results: All eight animals demonstrated successful spinal fusion four weeks postoperatively. Additionally, this group demonstrated fusion at L3-L4, despite the lack of a surgically-prepared fusion bed.
Group II was treated with adipose-derived stem cells treated with osteogenic media and 1 μg/mL of recombinant BMP-2.
Results: The animals experienced minimal bone formation eight weeks post-op.
Group III was treated with 10 μg of recombinant BMP-2 and Group IV was treated with 1 μg of recombinant BMP-2.
Results: Group III, which received a higher dose of recombinant BMP-2, showed more bone formation than the lower-dose Group IV.
Group V was treated with adipose-derived stem cells alone.
Results: None of the animals demonstrated spinal fusion eight weeks after surgery.
A gene therapy treatment similar to the one modeled by Group I has a number of benefits for clinical practice. Among other benefits, it's less expensive, as current recombinant BMP products require a large amount of protein; the adenoviral vector containing BMP-2 contains a smaller amount of protein that can also be delivered over a long period of time, whereas recombinant protein degrades. The treatment could also be safer for patients; InFuse, for example, has been shown to cause swelling when used off-label in cervical spine surgeries.
Despite the promise of the gene therapy treatment as identified in rats, the authors conclude that before the treatment can be considered appropriate for humans, it will be necessary to study further the treatment's biological potential, interactions between different carriers and the influence of host biology.
