The Influence Of Incorporation Of PRP And Ppp And Cu²⁺ Doping On The Properties Of Calcium Phosphate Cement

In view of the current calcium phosphate cement (CPC) having no osteoinductivity andproangiogenesis, in this paper, CPC was modified by incorporation of platelet-rich plasma(PRP) powder and platelet-poor plasma (PPP) powders, and copper ion doping, respectively,to get better cell response, which could lay a foundation for improving the osteoinductivityand proangiogenesis of CPC. The physical and chemical properties (phase composition,microstructure, setting time and mechanical properties, etc.) and especially the cell responsesof modified CPC have been studied systematically.The PRP and PPP powders were fabricated by successively freezing, thawing, andfreezed-drying the PRP and PPP, then incorporated into the CPC in various proportions. Theresults showed that incorporation of PRP or PPP powders did not affect the hydration productsand crystal morphology of CPC, but prolonged the setting time and obviously decreased thecompressive strength. The incorporation of proper amount of PRP and PPP powderssignificantly improved the injectability of CPC, which was more conducive to its applicationin minimally invasive surgery. Moreover, the incorporation of appropriate amount of PRP andPPP powders significantly promoted the proliferation, adhesion and differentiation of humanbone marrow mesenchymal stem cells (hMSCs). However, incorporating high amount of PRPor PPP powders was detrimental to the cells proliferation and differentiation. IncorporatingPRP or PPP powders had no obvious effect on promoting human umbilical vein endothelialcells (HUVECs) proliferation, but apparently promoted the expression of endothelial nitricoxide synthase (eNOS), an angiogenesis factor, in the early stage. In the later culturing stage,PRP still showed a significant role in promoting eNOS expression, comparatively, theeffectiveness of PPP lost because of low growth factor concentration which was consumedearly. The incorporation of5%PRP into CPC not only improved hMSCs proliferation,adhesion and differentiation, but also promoted eNOS expression. Therefore, theosteoinductivity and angiogenesis of CPC was promisingly enhanced by incorporating5%PRP powders.The copper ion (Cu2+) was doped into CPC by adopting copper sulfate solution as settingliquid and incorporating copper-substituted tricalcium phosphate (Cu-TCP), respectively. As for the CPC using copper sulfate solution as setting liquid, the doped Cu2+would affect thehydration reaction, which prolonged the setting time, changed the crystalline morphology ofhydration products, and improved the compressive strength but did not affect the the mainhydration products of CPC. With respect to the CPC incorporating Cu-TCP, the doped Cu2+was not involved in hydration reaction because of its slow release. Therefore, the doped Cu2+did not change the phase composition and crystal morphology of hydrated CPC, butdramatically increased the compressive strength of CPC. The Cu2+was steadily released fromboth modified CPC. Rat bone marrow mesenchymal stem cells (rMSCs) and HUVECs werecultured in extract liquids of both modified CPCs. The appropriate low Cu2+concentration inextracts slightly promoted rMSCs proliferation, but significantly promoted the HUVECsproliferation, adhesion and eNOS expression. However, higher concentration of Cu2+showeddistinct cytotoxicity to rMSCs and HUVECs. And lower release concentration of Cu2+had noobvious role in promoting rMSCs and HUVECs proliferation and adhesion.