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GDF-5 used to successfully get stromal cells to differentiate and form bone-like matrix
A study of adipose-derived cells confirmed they have potential as a possible bone graft substitute.
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SEATTLE — Multipotential adipose-derived stromal cells have demonstrated bone-like properties, according to initial reports from University of Virginia researchers.
The investigators said they will look into in vivo studies and perhaps one involving a posterolateral fusion animal model, said orthopedic surgeon Francis H. Shen, MD, to the North American Spine Society annual meeting, here. "The early work is pretty encouraging," he said.
Shen credited his colleague Qing Zeng, MD, for making the project possible. The Spine Journal awarded the team an outstanding paper award for its work.
Used GDF-5/BMP-14
The researchers successfully isolated adipose-derived stromal (ADS) cells from rats. After putting them in osteogenic media, they treated the ADS cells with growth and differentiation factor-5 (GDF-5). They used the ADS cells because they are readily available and have been shown to have multipotential ability. The researchers theorized that GDF-5 protein, also known as bone morphogenetic protein-14 or BMP-14, would help stimulate the bone inductivity properties of the ADS cells.
The researchers then seeded the cells on a 3D scaffold made of sintered poly lactide-co-glycolide [85:15] microspheres. By heating the microsphere matrix structure to 80° C for 3 hours, they caused it to develop an appropriate number of pores of a size that were conducive to ADS cell migration and proliferation, about 100 µm to 250 µm. The scaffold also met the criteria for the necessary compressive modulus required in a potential substitute for bone graft, he said.
Lab work results
They found promising results in the cultured ADS cells for such properties as cell viability, ability to undergo osteoblastic differentiation and gene expression. For example, with von Kossa staining, the cells showed signs of mineralization as compared to controls. They also saw the cells had significantly increased levels of the early and late genetic markers, osteocalcin and Cbfa1, compared to controls.
For 4 weeks they followed the activity of the cells and noticed a spike in the marker for osteoblastic activity at 14 days. Furthermore they found an increase in the osteoblastic markers for the 4 weeks."
They also tracked the cells' characteristic cytoplasmic extension of cells, first as a monolayer on the matrix and later as a film across some of the scaffolds using scanning electron microscopy.
They confirmed the cells within the scaffold remained viable through 28 days by checking their mitochondrial dehydrogenase activity with an MTS assay.
"The cells on the scaffold have the ability to look mechanically and structurally similar to trabecular bone," Shen said.
For more information:
- Shen FH, Zeng Q, Lu Q, et al. Osteogenic differentiation of adipose-derived stromal cells treated with GDF-2 cultured on a novel three-dimensional sintered microsphere matrix. #OPA-2. Presented at the North American Spine Society 21st Annual Meeting. Sept. 26-30, 2006. Seattle.
- Francis H. Shen, MD, is in the department of orthopedics, University of Virginia, P.O. Box 800159, Charlottesville, VA 22908. He can be contacted at 434-243-0291, fax: 434-243-0242, fhs2g@virginia.edu.
- The authors report the study was supported in part by the NIH-NIAMS, the Musculoskeletal Transplant Foundation Career Development Award, the Scoliosis Research Society, AO Foundation and the Orthopaedic Research and Education Foundation Career Development Award.