Page 160 - Cellular Imaging in Regenerative Medicine, Cancer and Osteoarthritis

Chapter 7
of SSTR2 targeting tracers in studying macrophage involvement in disease processes. Macrophages are crucial in the development and progression of various diseases and that is why accurate imaging of pro-inflammatory macrophages, beside the already established anti-inflammatory macrophage tracers (11, 45), might be an important step forward in understanding disease development. This is also indicated by recent publications on studies in which macrophages are being imaged in atherosclerotic plaques using the folate, mannose and somatostatine type 2 receptor (18, 46, 47).
Conclusion
Our research showed that pro-inflammatory macrophages (IFNγ+TNFα stimulated) had elevated SSTR2 expression and show concomitant elevated binding of SSTR2-targeting radiolabeled peptides suitable as SPECT tracers. Under pro-inflammatory conditions there was an increase in presence of CD64+ cells especially at day 1 and 3 after OA induction. In vivo SSTR2 SPECT imaging showed an increase of radioactivity in the knee at day 1-7 after OA induction. So, SSTR2 can be a marker to longitudinally monitor pro-inflammatory macrophages in vivo.
Conflicts of interest
None declared
Acknowledgments
All imaging experiments were conducted at the Applied Molecular Imaging at Erasmus MC Facility (AMIE; https://www.erasmusmc.nl/en/research/ core-facilities/amie). This research was done within the postgraduate school Molecular Medicine, Erasmus MC, University Medical Center, the Netherlands. The authors thank Joost Haeck, Gabriela Doeswijk, Mirjam Pikaart and Nicole Kops for their expert assistance during the studies and Mark Konijnenberg for his statistical analysis of the data.
158