Direct metal printed (DMP) porous iron implants possess promising mechanical and corrosion properties for various clinical application. Nevertheless, there is a requirement for better co-relation between in vitro and in vivo corrosion and biocompatibility behaviour of such biomaterials. Our present study evaluates absorption of porous iron implants under both static and dynamic conditions. Furthermore, this study characterizes their cytocompatibility using fibroblastic, osteogenic, endothelial and macrophagic cell types. In vitro degradation was performed statically and dynamically in a custom-built set-up placed under cell culture conditions (37 °C, 5% CO2 and 20% O2) for 28 days. The morphology and composition of the degradation products were analysed by scanning electron microscopy (SEM, JSM-IT100, JEOL). Iron implants before and after immersion were imaged by μCT (Quantum FX, Perkin Elmer, USA). Biocompatibility was also evaluated under static and dynamic in vitro culture conditions using L929, MG-63, HUVEC and RAW 264.7 cell lines. According to ISO 10993, cytocompatibility was evaluated directly using live/dead staining (Live and Dead Cell Assay kit, Abcam) in dual channel fluorescent optical imaging (FOI) and additionally quantified by flow cytometry. Furthermore, cytotoxicity was indirectly quantified using ISO conform extracts in proliferation assays. Strut size of DMP porous iron implants was 420 microns, with a porosity of 64% ± 0.2% as measured by micro-CT. After 28 days of physiological degradation in vitro, dynamically tested samples were covered with brownish degradation products. They revealed a 5.7- fold higher weight loss than statically tested samples, without significant changes in medium pH. Mechanical properties (E = 1600–1800 MPa) of these additively manufactured implants were still within the range of the values reported for trabecular bone, even after 28 days of biodegradation. Less than 25% cytotoxicity at 85% of the investigated time points was measured with L929 cells, while MG-63 and HUVEC cells showed 75% and 60% viability, respectively, after 24 h, with a decreasing trend with longer incubations. Cytotoxicity was analysed by two-way ANOVA and post-hoc Tukey's multiple comparisons test. Under dynamic culture conditions, live-dead staining and flow cytometric quantification showed a 2.8-fold and 5.7-fold increase in L929 and MG-63 cell survival rates, respectively, as compared to static conditions. Therefore, rationally designed and properly coated iron-based implants hold potential as a new generation of absorbable Orthopaedic implants.
Ketamine has been used in combination with a
variety of other agents for intra-articular analgesia, with promising results.
However, although it has been shown to be toxic to various types
of cell, there is no available information on the effects of ketamine
on chondrocytes. We conducted a prospective randomised controlled study to evaluate
the effects of ketamine on cultured chondrocytes isolated from rat
articular cartilage. The cultured cells were treated with 0.125
mM, 0.250 mM, 0.5 mM, 1 mM and 2 mM of ketamine respectively for
6 h, 24 hours and 48 hours, and compared with controls. Changes of
apoptosis were evaluated using fluorescence microscopy with a 490
nm excitation wavelength. Apoptosis and eventual necrosis were seen
at each concentration. The percentage viability of the cells was
inversely proportional to both the duration and dose of treatment
(p = 0.002 and p = 0.009). Doses of 0.5 mM, 1 mM and 2mM were absolutely
toxic. We concluded that in the absence of solid data to support the
efficacy of intra-articular ketamine for the control of pain, and
the toxic effects of ketamine on cultured chondrocytes shown by
this study, intra-articular ketamine, either alone or in combination
with other agents, should not be used to control pain. Cite this article:
