Background: Osteonecrosis of the femoral head (ONFH) is a disabling disease. Early treatment is crucial to the prognosis of the disease. Core decompression (CD) is one of the most commonly used methods for the treatment of early ONFH. But it could not prevent the collapse of the necrotic femoral head. How to improve the therapeutic effect of early ONFH on the basis of CD has become an area of focused research.
Methods: Functional β-tricalcium phosphate (β-TCP) scaffolds modified by DPIYALSWSGMA (DPI) peptide, a bone marrow-derived mesenchymal stem cell (BMSC) affinity peptide, were constructed using an adsorption/freeze-drying strategy. The affinity of DPI peptide towards rabbit BMSCs was investigated using flow cytometry and fluorescence cytochemistry. In vitro cell adhesion assay was performed to study the adherent ability of rabbit BMSCs on functional β-TCP scaffolds. After the rabbit model of early ONFH was established, DPI peptide-modified and pure β-TCP scaffolds were transplanted into the remaining cavity after CD. Meanwhile, rabbits treated with pure CD were used as blank control. Twelve weeks after surgery, histological analysis was performed to show the therapeutic effect of three methods on early ONFH.
Results: The result of ImageXpress Micro Confocal indicated that fabricated DPI peptide-modified functional β-TCP scaffolds exhibited green fluorescence. In flow cytometry, the average fluorescence intensity for rabbit BMSCs incubated with FITC-DPI was significantly higher than that of FITC-LSP (P = 2.733 × 10-8). In fluorescence cytochemistry, strong fluorescent signals were observed in rabbit BMSCs incubated with FITC-DPI and FITC-RGD, whereas no fluorescent signals in cells incubated with FITC-LSP. In cell adhesion assay, the number of adherent cells to β-TCP-DPI scaffolds was more than that of pure β-TCP scaffolds (P = 0.033). The CD + β-TCP-DPI group expressed the lowest vacant bone lacunae percentage compared to CD group (P = 2.350 × 10-4) and CD + β-TCP group (P = 0.020). The expression content of COL1 in CD + β-TCP-DPI group was much higher than CD group (P = 1.262 × 10-7) and CD + β-TCP group (P = 1.666 × 10-7) according to the integrated optical density (IOD) analyses.
Conclusion: Functional β-TCP scaffolds modified by DPI peptide were successfully synthesized using an adsorption/freeze-drying strategy. DPI peptide has good affinity towards rabbit BMSCs. The adhesion of rabbit BMSCs on DPI peptide-modified β-TCP scaffolds was apparently enhanced. CD followed by implantation of DPI peptide-modified β-TCP scaffolds can apparently improve the treatment of early ONFH compared with pure CD and CD followed by implantation of unmodified β-TCP scaffolds. Our current study provides an improved method for the treatment of early ONFH.
Keywords: Affinity peptide; Bone marrow-derived mesenchymal stem cell; Osteonecrosis of the femoral head; β-tricalcium phosphate.