Objectives The aim of
this study was to assess the potential of noninvasive and repeated
monitoring of rhACE2 distribution and content in organs using the
ACE2-specific nuclide probe 68Ga-HZ20.
Methods We optimized the labeling conditions of the probe and
evaluated its safety. A mouse organ in situ rhACE2
high-aggregation model was constructed for the first time, and in
vivo real-time PET imaging of rhACE2 was performed using the
ACE2-specific PET agent 68Ga-HZ20. The distribution
and uptake of the probe were analyzed, and the model was validated.
Results This radiotracer exhibited reliable radiochemical
properties in vitro and maintained a high affinity for rhACE2in vivo . In terms of probe uptake, 68Ga-HZ20
showed a good target-to-nontarget
ratio, and the correlation between the uptake value of the probe and the
dose of rhACE2 was >90% in both models; the probe was
rapidly cleared from the circulatory system and excreted by the kidneys
and urinary system. No organs were damaged after the injection of high
doses of probe.
Conclusions This technology for noninvasively and repeatedly
monitoring the content and distribution of rhACE2 in vivo aids in
clarifying the resident capacity of rhACE2 in organs and in analyzing
the preventive effect of rhACE2 against SARS-CoV-2 and the effectiveness
of therapies for COVID-19.
Keywords: SARS-CoV-2, PET imaging, 68Ga-HZ20,
rhACE2-organ model