Evaluating the abnormal ossification in tibiotarsi of developing chick embryos exposed to 1.0 ppm doses of platinum group metals by spectroscopic techniques

• Published in: Bone (New York, N.Y.) Vol. 53; no. 2; pp. 421 - 429
• Main Authors: Stahler, Adam C, Monahan, Jennifer L, Dagher, Jessica M, Baker, Joshua D, Markopoulos, Marjorie M, Iragena, Diane B, NeJame, Britney M, Slaughter, Robert, Felker, Daniel, Burggraf, Larry W, Isaac, Leon A.C, Grossie, David, Gagnon, Zofia E, Sizemore, Ioana E. Pavel
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01-04-2013
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Orthopedics; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Chick embryo tibiotarsi; Micro-XRF imaging; Histology; Micro-Raman imaging; Platinum group metals; FAAS; Embryo; Morphology; Metal; Technique; Dose; Ossification
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2012.12.051

Abstract Platinum group metals (PGMs), i.e., palladium (Pd), platinum (Pt) and rhodium (Rh), are found at pollutant levels in the environment and are known to accumulate in plant and animal tissues. However, little is known about PGM toxicity. Our previous studies showed that chick embryos exposed to PGM concentrations of 1 mL of 5.0 ppm (LD50 ) and higher exhibited severe skeletal deformities. This work hypothesized that 1.0 ppm doses of PGMs will negatively impact the mineralization process in tibiotarsi. One milliliter of 1.0 ppm of Pd(II), Pt(IV), Rh(III) aqueous salt solutions and a PGM-mixture were injected into the air sac on the 7th and 14th day of incubation. Control groups with no-injection and vehicle injections were included. On the 20th day, embryos were sacrificed to analyze the PGM effects on tibiotarsi using four spectroscopic techniques. 1) Micro-Raman imaging: Hyperspectral Raman data were collected on paraffin embedded cross-sections of tibiotarsi, and processed using in-house-written MATLAB codes. Micro-Raman univariate images that were created from the ν1 (PO4 3 − ) integrated areas revealed anomalous mineral inclusions within the bone marrow for the PGM-mixture treatment. The age of the mineral crystals (ν(CO3 2 − )/ν1 (PO4 3 − )) was statistically lower for all treatments when compared to controls (p ≤ 0.05). 2) FAAS : The percent calcium content of the chemically digested tibiotarsi in the Pd and Pt groups changed by ~ 45% with respect to the no-injection control (16.1 ± 0.2%). 3) Micro-XRF imaging : Abnormal calcium and phosphorus inclusions were found within the inner longitudinal sections of tibiotarsi for the PGM-mixture treatment. A clear increase in the mineral content was observed for the outer sections of the Pd treatment. 4) ICP-OES: PGM concentrations in tibiotarsi were undetectable ( < 5 ppb). The spectroscopic techniques gave corroborating results, confirmed the hypothesis, and explained the observed pathological (skeletal developmental abnormalities) and histological changes (tibiotarsus ischemia and nuclear fragmentation in chondrocytes).