The Quarterly Journal of Nuclear Medicine and Molecular Imaging 2020 Jun 15

DOI: 10.23736/S1824-4785.20.03225-2

Copyright © 2020 EDIZIONI MINERVA MEDICA

lingua: Inglese

Using 99mTc-(V)-DMSA to follow the vascular calcification process in vascular smooth muscle cells based on pit-1 expression

Pierre-Benoît BONNEFOY ^{1, 2} ✉, Elodie JACQUEROUX ¹, Xavier DELAVENNE ¹, Frederic ROCHE ³, Anthony CLOTAGATIDE ⁴, Patrick MISMETTI ¹, Nathalie PREVOT ^{1, 2}, Nathalie PEREK ¹

¹ INSERM U1059 Dysfonction Vasculaire et Hémostase, Université de Lyon, UJM-Saint-Etienne, Saint-Étienne, France; ² Service de Médecine nucléaire, CHU de Saint-Etienne, Saint-Étienne, France; ³ EA4607 SNA-EPIS, Université de Lyon - UJM-Saint-Etienne, Saint-Etienne, France; ⁴ Service de Radiopharmacie Clinique, CHU de Saint-Etienne, Saint-Étienne, France

BACKGROUND: Vascular calcification is an established feature of atherosclerosis process. The sodium/phosphate transporter PiT-1 acts as a biosensor in vascular calcification of VSMCs. [99mTc]-Pentavalent dimercaptosuccinic acid (99mTc-(V)-DMSA) was mediated by PiT-1 transporter in tumoral cells and we propose its evaluation in a vascular calcification in vitro model. The aim of this study was to determine if 99mTc-(V)-DMSA can follow the vascular calcification process in vascular smooth muscle cells (VSMCs) based on PiT-1 expression.
METHODS: From a rat aortic VSMC cell line (A7r5), we set up a model of calcification within 7 days using a calcifying medium containing a high inorganic phosphate concentration. Phosphocalcic deposits were monitored with Alizarin red and Von Kossa staining and with phase contrast microscopy. PiT-1 expression was evaluated with an immunofluorescence assay and osteopontin expression, with whole cell ELISA assay. 99mTc-(V)-DMSA uptake was measured in control and calcifying conditions and compared with optical microscopy evaluation.
RESULTS: Under hyperphosphatemia conditions, the VSMC cells progressively overexpressed osteopontin protein, PiT-1 transporter, and synthetized mineralized matrix with phosphocalcic deposition. 99mTc-(V)-DMSA uptake was to 2.8+/-2.08%DA/mg-protein in control cells and 42+/-24%DA/mg-protein in calcified cells (p<0,001). PiT-1 inhibition with phosphonoformic acid completely reverse the calcium deposition as well as the 99mTc-(V)- DMSA uptake. These results demonstrated that 99mTc-(V)-DMSA in vitro uptake is mediated by PiT-1 transporter and follow the VSMC calcification process.
CONCLUSIONS: These preliminary in vitro results showed 99mTc-(V)-DMSA uptake follow the phospho-calcic deposition mediated by PiT-1 transporter. This radiotracer may have some potential to detect changes of VSMC metabolism occurring in the atherosclerosis process.

KEY WORDS: Vascular calcification; 99mTc-(V)-DMSA; PiT-1 transporter; A7r5 cell line; Molecular Imaging