Abstract
BackgroundPromotion of bone regeneration is important for successful repair of bony defects. This study aimed to investigate whether combining bone marrow-derived mesenchymal stem cell (BMSC) sheets with platelet-rich plasma (PRP) gel/calcium phosphate particles could promote bone formation in the femoral bone defects of rats.MethodsThe proliferation and differentiation of BMSCs or BMSC sheets cultured with calcium phosphate particles and/or PRP were investigated in in vitro. In vivo, 36 2.5 × 5 mm bone defects were randomly divided into groups and treated with either BMSCs/PRP gel, calcium phosphate particles, PRP gel/calcium phosphate particles, a BMSC sheet/calcium phosphate particles, a BMSC sheet/PRP gel/calcium phosphate particles, or were left untreated (n = 6/group). A further 15 bone defects were treated with chloromethyl-benzamidodialkylcarbocyanine (CM-Dil)-labelled BMSC sheet/PRP gel/calcium phosphate particles and observed using a small animal in vivo fluorescence imaging system to trace the implanted BMSCs at 1 day, 3 days, 7 days, 2 weeks, and 4 weeks after surgery.ResultsThe expression of collagen type I and osteocalcin genes of BMSCs or BMSC sheets treated with PRP and calcium phosphate particles was significantly higher than that of BMSCs or BMSC sheets treated with calcium phosphate particles or the controls (P <0.05). PRP can promote gene expression of collagen III and tenomodulin by BMSCs and in BMSC sheets. The VEGF, collagen I and osteocalcin gene expression levels were higher in the BMSC sheet than in cultured BMSCs (P <0.05). Moreover, alizarin red staining quantification, ALP quantification and calcein blue fluorescence showed the osteogenic potential of BMSCs treated with PRP and calcium phosphate particles The implanted BMSCs were detectable at 1 day, 3 days, 7 days, 2 weeks and 4 weeks after surgery by a small animal in vivo fluorescence imaging system and were visualized in the defect zones by confocal microscopy. At 4 weeks after implantation, the defects treated with the BMSC sheet/PRP gel/calcium phosphate particles showed significantly more bone formation than the other five groups.ConclusionsIncorporation of an BMSC sheet into the PRP gel/calcium phosphate particles greatly promoted bone regeneration. These BMSC sheet and tissue engineering strategies offer therapeutic opportunities for promoting bone defect repair clinically.
Highlights
Promotion of bone regeneration is important for successful repair of bony defects
After the platelet-rich plasma (PRP) gel and PRP gel/calcium phosphate (CaP) particles were incubated at 37 °C for 30 minutes, and lyophilized in a freeze dryer (Heto Power Dry LL1500), the PRP gel and PRP gel/CaP particle composites were observed by scanning electron microscopy (SEM) (Fig. 4b, c)
The results of this study demonstrated that incorporation of a bone marrow-derived mesenchymal stem cell (BMSC) sheet along with PRP gel/CaP particles greatly promoted bone regeneration
Summary
This study aimed to investigate whether combining bone marrow-derived mesenchymal stem cell (BMSC) sheets with platelet-rich plasma (PRP) gel/calcium phosphate particles could promote bone formation in the femoral bone defects of rats. BMSCs combined with various materials have been found to regenerate bone defects using cell suspension systems [3,4,5]. The cell suspension systems have fewer advantages or cannot be used with scaffolds of non-porous materials or particles. To address this issue, we adopted a cell transplantation method in which BMSCs are cultured and lifted as a cell sheet structure. The BMSC sheet can be detached from the culture substrate, while the extracellular matrix (ECM), the adhesion molecules on the cell surface, and cell-cell interactions remain intact [8]
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