Isostructural fluorescent and radioactive probes for monitoring neural stem and progenitor cell transplants

Schaffer, Paul; Gleave, Jacqueline A.; Lemon, Jennifer A.; Reid, Leslie C.; Pacey, Laura K.K.; Farncombe, Troy H.; Boreham, Douglas R.; Zubieta, Jon; Babich, John W.; Doering, Laurie C.; Valliant, John F.

doi:10.1016/j.nucmedbio.2007.11.001

« Previous Next »Nuclear Medicine and Biology
Volume 35, Issue 2 , Pages 159-169, February 2008

Isostructural fluorescent and radioactive probes for monitoring neural stem and progenitor cell transplants

Paul Schaffer
- McMaster Nuclear Reactor, McMaster University, Hamilton, Ontario, Canada L8S 4K1
Jacqueline A. Gleave
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
Jennifer A. Lemon
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada L8S 4K1
Leslie C. Reid
- Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1
Laura K.K. Pacey
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
Troy H. Farncombe
- Department of Nuclear Medicine, Hamilton Health Sciences, Hamilton, Ontario, Canada L8N 3Z5
Douglas R. Boreham
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada L8S 4K1
Jon Zubieta
- Department of Chemistry, Syracuse University, Syracuse, NY 13244-4100, USA
John W. Babich
- Molecular Insight Pharmaceuticals Inc., Cambridge, MA 02142, USA
Laurie C. Doering
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
John F. Valliant
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada L8S 4K1
- Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1
- Corresponding author. Department of Chemistry, McMaster University, 1280 Main St. West, Hamilton, Ontario, Canada L8S 4M1. Tel.: +1 905 525 9140x22840; fax: +1 905 522 7776.

Received 25 July 2007; received in revised form 25 September 2007; accepted 2 November 2007.

Abstract

A construct for tagging neurospheres and monitoring cell transplantations was developed using a new technology for producing luminescent and radiolabeled probes that have identical structures. The HIV1-Tat basic domain derivatives NAcGRKKRRQRRR(SAACQ)G (SAACQ-1) and [NAcGRKKRRQRRR(Re(CO)₃SAACQ)G]⁺ (ReSAACQ-1) were prepared in excellent yields using the single amino acid chelate-quinoline (SAACQ) ligand and its Re(I) complex and conventional automated peptide synthesis methods. The distribution of the luminescent Re probe, using epifluorescence microscopy, showed that it localized primarily in the cell nucleus with a significant degree of association on the nuclear envelope. A smaller amount was found to be dispersed in the cytoplasm. The ^99mTc analogue was then prepared in 43±7% (n=12) yield and very high effective specific activity. Following incubation, average uptake of the probe in neurospheres ranged between 10 and 20 Bq/cell. As determined by colorimetric assays, viability for cells labeled with high effective specific activity ^99mTcSAACQ-1 was 97±4% at 2 h postlabeling and 85±25% at 24 h postlabeling for incubation activities ranging from 245 to 8900 Bq/cell. DNA analysis showed that at these levels, there was no significant difference between the extent of DNA damage in the treated cells versus control cells. A series of preliminary SPECT/CT studies of transplants in mice were performed, which showed that the strategy is convenient and feasible and that it is possible to routinely assess procedures noninvasively and determine the number of cells transplanted.

Keywords: Neurospheres, Imaging, Technetium, Transplants, Peptide