Radiolabeling Rhesus Monkey CD34+ Hematopoietic and Mesenchymal Stem Cells with 64Cu-Pyruvaldehyde-Bis(N4- Methylthiosemicarbazone) for MicroPET Imaging.

Noninvasive positron emission tomography (PET) provides a potential method for in vivo tracking of radiolabeled cells. The goal of this study was to assess the potential toxicity of ⁶⁴Cu-pyruvaldehyde-bislN4-methylthiosemicarbazone) (PTSM) on rhesus monkey CD34⁺ hematopoietic and mesenchymal stem cells in vitro in preparation for developing imaging protocols posttransplantation. CD34⁺ hematopoietic cells were radiolabeled with 0 to 40 µCi/mL ⁶⁴Cu-PTSM and viability and colony formation were assessed. Rhesus monkey mesenchymal stem cells (rhMSCs) were placed in culture postradiolabeling for assessments of growth and differentiation toward adipogenic, osteogenic, and chondrogenic lineages. The results indicated that CD34⁺ cells radiolabeled with 20 µCi/mL and rhMSCs radiolabeled with 10 µCi/mL ⁶⁴Cu-PTSM did not result in adverse effects on growth or differentiation, Nonradioactive copper was also evaluated and showed that the presence of copper was not harmful to the cells. CD34⁺ cells and rhMSCs radiolabeled with the optimized concentrations of 20 and 10 µCi/mL, respectively, were also assessed using the microPET scanner. Studies showed that a minimum of 2.50 x 10⁴ CD34⁺ cells (1.1 pCi/cell) and 6.25 x 10³ rhMSCs (4.4 pCi/cell) could be detected. These studies indicate that CD34⁺ hematopoietic cells and rhMSCs can be safely radiolabeled with ⁶⁴Cu-PTSM without adverse cellular effects. [ABSTRACT FROM AUTHOR]