No abstract

Magnesium calcium phosphate biocement (MCPB) with rapid-setting characteristics was fabricated by using the mixed powders of magnesium oxide (MgO) and calcium dihydrogen phosphate (Ca(H 2 PO 4 ) 2 . H 2 O). The results revealed that the MCPB hardened after mixing the powders with water for about 7 min, and the compressive strength reached 43 MPa after setting for 1 h, indicating that the MCPB had a short setting time and high initial mechanical strength. After the acid -base reaction of MCPB containing MgO and Ca(H 2 PO 4 ) 2 . H 2 O in a molar ratio of 2 : 1, the final hydrated products were Mg 3 (PO 4 ) 2 and Ca 3 (PO 4 ) 2 . The MCPB was degradable in Tris-HCl solution and the degradation ratio was obviously higher than calcium phosphate biocement (CPB) because of its fast dissolution. The attachment and proliferation of the MG 63 cells on the MCPB were significantly enhanced in comparison with CPB, and the alkaline phosphatase activity of MG 63 cells on the MCPB was significantly higher than on the CPB at 7 and 14 days. The MG 63 cells with normal phenotype spread well on the MCPB surfaces, and were attached in close proximity to the substrate, as seen by scanning electron microscopy (SEM). The results demonstrated that the MCPB had a good ability to support cell attachment, proliferation and differentiation, and exhibited good cytocompatibility.

Mesoporous silica xerogels with various amount of calcium (0, 5, 10 and 15%, named m-SXC0, m-SXC5, m-SXC10 and m-SXC15, respectively) were synthesized by template sol-gel methods, and cell responses to m-SXCs were studied using murine pre-osteoblast MC3T3-E1 in vitro. The results showed that cell morphology was not affected by m-SXCs indicating good biocompatibility. Furthermore, cell proliferation ratio on the m-SXCs increased over time, among which m-SXC10 was highest. NO production obviously rose with the increase of Ca content in m-SXCs. ALP activity and PGE(2) level on m-SXC5 significantly improved compared with m-SXC0 while decreased with the increase of Ca content for m-SXC10 and m-SXC15. No obvious discrepancy on osteopontin mRNA expressions was observed among m-SXCs. The collagen I and osteocalcin mRNA expression on m-SXC5 were up-regulated, while decreased on m-SXC15 evidently. The phosphorylation level of ERK 1/2 for the m-SXC10 was highest after 7 days. In conclusion, calcium in m-SXCs plays an important role in osteoblast activity, which indicates mesoporous silica xerogel containing appropriate calcium could stimulate osteoblast proliferation, differentiation, gene expression via the activation of ERK 1/2 signaling pathway, and shows great prospects in bone regeneration field using as a drug controlled release filler.

In the present study, we fabricated magnesium doped apatite cement (md-AC) with rapid self-setting characteristic by adding the mixed powders of magnesium oxide and calcium dihydrogen phosphate (MO-CDP) into hydroxyapatite cement (HAC). The results revealed that the md-AC with 50 wt% MO-CDP could set within 6 min and the compression strength could reach 51 MPa after setting for 1 h, indicating that the md-AC had highly initial mechanical strength. The degradability of the md-AC in Tris-HCl solution increased with the increase of MO-CDP amount, and the weight loss ratio of md-AC with 50 wt% MO-CDP was 57.5 wt% after soaked for 12 weeks. Newly flake-like apatite could be deposited on the md-AC surfaces after soaked in simulated body fluid (SBF) for 7 days. Cell proliferation ratio of MG(63) cells on md-AC was obviously higher than that of HAC on days 4 and 7. The cells with normal phenotype spread well on the md-AC surfaces and attached intimately with the substrate, and alkaline phosphatase (ALP) activity of the cells on md-AC significantly improved compared with HAC on day 7. The results demonstrate that the md-AC has a good ability to support cell proliferation and differentiation, and indicate a good cytocompatibility.

A scaffold of nanofiber wollastonite (nf‐WS) and poly(ɛ‐caprolactone) (PCL) composite was fabricated, and the morphology, degradation, and cellular response to the scaffold were investigated. The results indicate that the composite scaffold contained open and interconnected pores ranging in size from 400 to 500 μm and exhibited a porosity of around 80%, as well as degradation of the scaffold in phosphate‐buffered saline. MTT tests demonstrated that MG63 cell proliferation was greater on the composite scaffold than on PCL alone at 4 and 7 days of culture. Moreover, the level of alkaline phosphatase activity of the cells cultured on the composite scaffold was higher than that in cells grown on PCL alone at 7 days, and scanning electron microscopy revealed significant osteoblast‐like adhesion and ingrowth into the composite scaffold. Elevated levels of calcium (Ca) and silicon (Si) were detected in the culture medium during cell culture, and the continuous dissolution of nf‐WS produced a Ca‐ and Si‐rich environment that might stimulate cellular proliferation and differentiation. The composite scaffold was bioactive, as indicated by the formation of an apatite layer on the scaffold surface after immersion in cell medium.