Quantification of cell labeling with micron-sized iron oxide particles using continuum source atomic absorption spectrometry.

Detection of cells after transplantation is necessary for quality control in regenerative medicine. Labeling with micron-sized iron oxide particles enables noninvasive detection of single cells by magnetic resonance imaging. However, techniques for evaluation of the particle uptake are challenging. The aim of this study was to investigate continuum source atomic absorption spectrometry (CSAAS) for this purpose. Porcine liver cells were labeled with micron-sized iron oxide particles, and the iron concentration of the cell samples was investigated by a CSAAS spectrometer equipped with a Perkin-Elmer THGA graphite furnace. The weak iron line at 305.754 nm provides only about 1/600 sensitivity of the iron resonance line at 248.327 nm and was used for CSAAS measurements. Iron concentrations measured from labeled cells ranged from 5.8 +/- 0.3 to 25.8 +/- 0.9 pg Fe/cell, correlating to an uptake of 8.2 +/- 0.5 to 25.7 +/- 0.8 particles/cell. The results were verified by standardized morphometric evaluation. CSAAS enabled rapid quantification of particle load from small quantities of cells without extensive preparation steps. Thereby, CSAAS could be used for quality control in a clinical setting of cell transplantation.