Characterizing the host response to rhPDGF-BB in a rat spinal arthrodesis model

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Regenerative Medicine

Background:

• Spinal fusion often uses autograft bone, but alternatives are sought due to limitations.
• Osteoinductive agents face challenges with efficacy and complications.
• Recombinant human platelet-derived growth factor B homodimer (rhPDGF-BB) is FDA-approved for other orthopedic uses.

Purpose of the Study:

• To characterize the in vivo host response to rhPDGF-BB in a rat spine fusion model.
• To evaluate the safety and inflammatory potential of rhPDGF-BB when delivered via a β-TCP/Col matrix.

Main Methods:

• Posterolateral spinal fusion was performed in 80 rats using iliac crest allograft, a control matrix, or the matrix with low or high doses of rhPDGF-BB.
• Animals underwent MRI and serum cytokine analysis at multiple postoperative time points.
• Immunofluorescence staining assessed neovascularization and cell proliferation (Ki67, vWF).

Main Results:

• No significant differences in fluid accumulation were observed via MRI across groups.
• Serum cytokine analysis revealed no clinically significant inflammatory response induced by rhPDGF-BB.
• Histology and immunofluorescence showed similar cell infiltration, proliferation, and neovascularization among all treatment groups.

Conclusions:

• rhPDGF-BB delivered with a β-TCP/Col matrix does not cause an exaggerated local or systemic inflammatory response compared to allograft or control.
• rhPDGF-BB in a β-TCP/Col matrix presents a potentially safe biologic alternative for spine fusion.
• Further research is needed to confirm the efficacy of rhPDGF-BB in spine fusion.