Strong Calcium Phosphate Cement-Chitosan-Mesh Construct Containing Cell-Encapsulating Hydrogel Beads for Bone Tissue Engineering

Published

April 25, 2006

Author(s)

Michael Weir, Hockin D. Xu, Carl G. Simon Jr.

Abstract

Calcium phosphate cement (CPC) can conform to complex cavity shapes and set in situ to form bioresorbable hydroxyapatite. The aim of this study was to introduce cell-encapsulating alginate hydrogel into CPC and to improve the mechanical properties using chitosan and fiber mesh reinforcement. Because the ionic activity and pH changes during the CPC setting reaction were harmful to the cells, alginate was used to encapsulate and protect MC3T3-E1 osteoblast cells in CPC. Cells were encapsulated into alginate beads of 2.2 mm diameter, and the beads were then mixed into pastes of conventional CPC, CPC-chitosan, and CPC-chitosan-mesh at bead volume fraction = 54 %. After 24 h culture inside the setting cements, cell double staining showed that live cells were numerous and dead cells were few. All specimens exhibited live cell densities > 80 %. Cell viability was assessed by measuring the mitochondrial dehydrogenase activity using a Wst-1 colorimetric assay. Absorbance at 450 nm (arbitrary units) (mean sd; n = 5) was (1.36 0.41) for cells inside conventional CPC, (1.29 0.24) for cells inside CPC-chitosan, and (0.73 0.22) for cells inside CPC-chitosan-mesh. All three were statistically similar to (1.00 0.14) for control with cells in beads in culture medium without CPC (Tukey s multiple comparison at 0.95). Flexural strength for conventional CPC containing cell-encapsulating beads was 1.3 MPa; it increased to 2.3 MPa with chitosan, 4.3 MPa with chitosan and one mesh, and 9.5 MPa with chitosan and three sheets of mesh on the specimen s tensile side. The latter two strengths matched reported strengths for sintered porous hydroxyapatite implants and cancellous bone. In summary, in situ hardening cell-alginate-CPC-chitosan constructs were developed that showed favorable cell viability inside the constructs. The use of chitosan and mesh progressively increased the mechanical properties.

Citation

Journal of Biomedical Materials Research Part A

Volume

77a

Pub Type

Journals

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Keywords

alginate hydrogel, bone tissue engineering, calcium phosphate cement, cell encapsulation, cytotoxicity, macroporous, mesh reinforcement

Citation

Weir, M. , Xu, H. and Simon, C. (2006), Strong Calcium Phosphate Cement-Chitosan-Mesh Construct Containing Cell-Encapsulating Hydrogel Beads for Bone Tissue Engineering, Journal of Biomedical Materials Research Part A, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852513 (Accessed July 26, 2024)