Description
In this study, the cytocompatibility and early osteogenic characteristics of rat bone marrow cells
(RBMCs) on injectable calcium phosphate (CaP) cement (Calcibon) were investigated. In addition to
unmodified CaP cement discs, 2 other treatments were given to the discs: preincubation in MilliQ and
sintering at different temperatures. After primary culture, RBMCs were dropwise seeded on the discs
and cultured for 12 days. The samples were evaluated in terms of cell viability, morphology (live and dead
assays and scanning electron microscopy (SEM)), cell proliferation (deoxyribonucleic acid (DNA) analyses),
early cell differentiation (alkaline phosphatase (ALP) activity), and physicochemical analyses (xray
diffraction (XRD)). The live and dead, DNA, and SEM results showed that Calcibon discs without
any additional treatment were not supporting osteoblast-like cells in vitro. There were fewer cells, and
cell layers were detached from the disc surface. Therefore, different preincubation periods and sintering
temperatures were evaluated to improve the cytocompatibility of the CaP cement. Preincubating discs in
MilliQ for periods of 1, 4, 8, and 12 weeks resulted in the hydrolysis of a-tri calcium phosphate (TCP)
into an apatite-like structure with some b-TCP, as shown with XRD, but the material was not cytocompatible.
Sintering the discs between 8008C and 11008C resulted in conversion of a-TCP to b-TCP
with some hydroxyapatite and an increase in crystallinity. Eventually, the discs sintered at 11008C
achieved better cell attachment, more-abundant cell proliferation, and earlier differentiation than other
sintered (6008C, 8008C, and 10008C), preincubated, and unmodified specimens. On basis of our results,
we conclude that in vivo results with CaP-based cements do not guarantee in vitro applicability. Furthermore,
unmodified Calcibon is not cytocompatible in vitro, although preincubation of the material
results in a more-favorable cell response, sintering of the material at 11008C results in the best osteogenic
properties. In contrast to in vivo studies, the Calcibon CaP cement is not suitable as a scaffold for cellbased
tissue-engineering strategies.