Quality control in transplantation of micron-sized iron oxide particle labelled liver cells by using continuum source atomic absorption spectrometry

Aim: Transplantation of liver cells is a promising approach for treating certain liver diseases. Labelling of hepatocytes prior to transplantation with micron-sized iron oxide particles (MPIOs) enables non-invasive detection of transplanted cells by clinical MR equipment. However, techniques for evaluation of the particle uptake are challenging. Aim of this study was to investigate continuum source atomic absorption spectrometry (CSAAS) for quantification of the particle load of MPIO-labelled liver cells.

Methods: Porcine liver cells were isolated from 3 donor pigs and labelled with increasing concentrations of MPIOs in adhesion. Labelled and native cells were enzymatically resuspended. Cell samples were purified by density gradient centrifugation and lysated. Iron concentration was investigated by CSAAS equipped with a Perkin-Elmer THGA graphite furnace (wavelength: 305.745nm; pyrolysis temp. 300°C, atomization temperature: 2100°C). Measurements were performed in triplicates. Results of CS-AAS measurements were compared with morphometric evaluated particle content of labelled cells.

Results: The weak iron line at 305.754 nm showed good linear dynamic range. No matrix and spectral interferences were observed for the investigated matrices. CSAAS measurements of MPIO-labelled liver cells resulted in iron concentrations from 7.56±0.33 to 29.52±1.02 pg Fe / viable cell. Particle uptake was 8±1/2 to 26±1 particle per cell, respectively. Correlated with the labelling efficiency of the cell samples, these data were consistent with the morphometric evaluated particle load.

Discussion: This study shows that CSAAS can be used for quantification of the particle load of MPIO-labelled liver cells. In contrast to conventional morphometric evaluation, CSAAS can be performed with small samples from resuspended cells immediately prior to application. This approach could enable quality control in the clinical transplantation of MPIO-labelled liver cells.

Literatur: 1) Raschzok N, Morgul MH, Pinkernelle J, Vondran FW, Billecke N, Kammer NN, Pless G, Adonopoulou MK, Leist C, Stelter L, Teichgraber U, Schwartlander R, Sauer IM. Imaging of primary human hepatocytes performed with micron-sized iron oxide particles and clinical magnetic resonance tomography. J Cell Mol Med. 2008; 12: 1384-94 2) Huang MD, Becker-Ross H, Florek S, Heitmann U, Okruss M. Direct determination of total sulfur in wine using a continuum-source atomic-absorption spectrometer and an air-acetylene flame. Anal Bioanal Chem. 2005; 382: 1877-81

MPIO - MRI - cell detection - continuum source atomic absorption spectrometry - liver cell transplantation