In vitro chondrocyte toxicity following long-term, high-dose exposure to Gd-DTPA and a novel cartilage-targeted MR contrast agent.
OBJECTIVE
To determine the concentrations exhibiting toxicity of a cartilage-targeted magnetic resonance imaging contrast agent compared with gadopentetate dimeglumine (Gd-DT-PA) in chondrocyte cultures.


METHODS
A long-term Swarm rat chondrosarcoma chondrocyte-like cell line was exposed for 48 h to 1.0-20 mM concentrations of diaminobutyl-linked nitroxide (DAB4-DLN) citrate, 1.0-20 mM Gd-DTPA, 1.0 μM staurosporine (positive control), or left untreated. Cell appearance, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays of metabolic activity, quantitative PicoGreen assays of DNA content, and calcein-AM viability assays were compared.


RESULTS
At 1.0-7.5 mM, minimal decrease in cell proliferation was found for both agents. At all doses of both agents, cell culture appearances were similar after 24 h of treatment. At the higher doses, differences in cell culture appearance were found after 48 h of treatment, with dose-dependent declines in chondrocyte populations for both agents. Concentration-dependent declines in DNA content and calcein fluorescence were found after 48 h of treatment, but beginning at a lower dose of DAB4-DLN citrate than Gd-DTPA. Dose-dependent decreases in MTT staining (cell metabolism) were apparent for both agents, but larger effects were evident at a lower dose for DAB-DLN citrate. Poor MTT staining of cells exposed for 48 h to 20 mM DAB4-DLN citrate probably indicates dead or dying cells.


CONCLUSIONS
The minimal effect of the long-term exposure of model chondrocyte cell cultures to DAB4-DLN citrate and Gd-DTPA concentrations up to 7.5 mM (3x typical arthrographic administration) is supporting evidence that these doses are acceptable for MR arthrography. The findings are reassuring given that the experimental exposure to the contrast agents at sustained concentrations was much longer than when used clinically.
Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
Sharon
S
Midura
Imaging Institute, A21, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.|NitroSci Pharmaceuticals, New Berlin, WI, 53151, USA.
Erika
E
Schneider
Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, 21201, USA.|NitroSci Pharmaceuticals, New Berlin, WI, 53151, USA.
Gerald M
GM
Rosen
Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. winalsc@ccf.org.|Imaging Institute, A21, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. winalsc@ccf.org.
Carl S
CS
Winalski
Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
Ronald J
RJ
Midura
D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage / Q000633:toxicity*; D050091:Dendrimers / Q000008:administration & dosage / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000633:toxicity*; D008279:Magnetic Resonance Imaging; D051381:Rats; D019311:Staurosporine; D014407:Tumor Cells, Cultured / Q000187:drug effects
D003287:Contrast Media; D050091:Dendrimers; D019311:Staurosporine; D019786:Gadolinium DTPA
Biochemistry; Cartilage; Contrast agent; Cytotoxicity; Dendrimer; Gadolinium; Gd-DTPA; MRI