Preparation And Properties Of Calcium Phosphate/Pectin Composite Bone Cements

Bone defects which mainly caused by trauma, fractures and bone tumors distresshuman health. Calcium phosphate bone cement is considered to have a bright future asbone defect repair material. Some CPCs have been used in clinical treatment andachieved effects. Although calcium phosphate bone cements have many good characterssuch as biocompatibility, osteoconductive, etc. Calcium phosphate cement can only beused in non-bearing area cause of its low strength. Furthermore, its degradation speed istoo slow to conduct the formation of new bone in vivo. And its biocompatibility alsoshould be further improved. All of above limited the clinical applications of CPC.Water or dilute phosphoric acid, the solidifying liquid of calcium phosphatecements, only play a simple role to promote curing. This study improved the solidifyingliquid by imitating extracellular matrix, took pectin solution which have similarstructure with the polysaccharides of extracellular matrix as the solidifying liquid,developed calcium phosphate/pectin composite bone cement (CPCP) with lots ofadvantages, such as high strength, excellent biocompatibility, promoting stem cells toosteoblast. This study also researched the influence between the cement componentsand properties and biology behaviors of human adipose-derived mesenchymal stemcells (hADSCs).Firstly, prepared calcium phosphate/pectin composite bone cement and evaluatedthe physical and chemical properties of it. We prepared TTCP which is the mainmaterial of CPC by solid-phase thermal reaction. Calcium phosphate/pectin compositebone cement is prepared by mixing an equimolar TTCP and DCPA with differentconcentrations of pectin solution. We used XRD and FTIR to analyze the composite andthe process of formation of CPCP. We found that pectin is the key factor of theproperties of CPCP. CPCP cannot influent the pH of the surrounding environment, butdecline the capacity of protein absorption relatively. The compressive strength of CPCP enhanced significantly with the content of pectin increased. The study also showed thatthe compressive strength is inversely to the solid/liquid ratio and proper ratio canenhance it.Secondly, we evaluated the biological properties of CPCP. We digested humanadipose to get mesenchymal stem cells and cultured the fourth generation hADSCs asseed cells. Study showed that CPCP had low cytotoxic, good biocompatibility. Pectinpromoted adhesion and proliferation of cells in the surface of CPC significantly. We canfound that cell growth in good condition on CPCP by Live/Dead stain. Results indicatedthat the alkaline phosphatase activity of the hADSCs was enhanced significantly byadding pectin which can also promote the differentiation of hADSCs to osteoblasts.In conclusion, CPCP can significantly enhance the compressive strength, promotethe adhesion and proliferation of cells and conduct the differentiation to osteoblastscause of added pectin.