Bracke N, Janssens Y, Wynendaele E, Tack L, Maes A, van de Wiele C, Sathekge M, de Spiegeleer B. Blood-brain barrier transport kinetics of NOTA-modified proteins: the somatropin case.
THE QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING : OFFICIAL PUBLICATION OF THE ITALIAN ASSOCIATION OF NUCLEAR MEDICINE (AIMN) [AND] THE INTERNATIONAL ASSOCIATION OF RADIOPHARMACOLOGY (IAR), [AND] SECTION OF THE SOCIETY OF... 2020;
64:105-114. [PMID:
29697217 DOI:
10.23736/s1824-4785.18.03025-x]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
BACKGROUND
Chemical modifications such as PEG, polyamine and radiolabeling on proteins can alter their pharmacokinetic behavior and their blood-brain barrier (BBB) transport characteristics. NOTA, i.e. 1,4,7-triazacyclononane-1,4,7-triacetic acid, is a bifunctional chelating agent that has attracted the interest of the scientific community for its high complexation constant with metals like gallium. Until now, the comparative BBB transport characteristics of NOTA-modified proteins versus unmodified proteins are not yet described.
METHODS
Somatropin (i.e. recombinant human growth hormone), NOTA-conjugated somatropin and gallium-labelled NOTA-conjugated somatropin were investigated for their brain penetration characteristics (multiple time regression and capillary depletion [CD]) in an in vivo mice model to determine the blood-brain transfer properties.
RESULTS
The three compounds showed comparable initial brain influx, with Kin=0.38±0.14 µL/(g×min), 0.36±0.16 µL/(g×min) and 0.28±0.18 µL/(g×min), respectively. CD indicated that more than 80% of the influxed compounds reached the brain parenchyma. All three compounds were in vivo stable in serum and brain during the time frame of the experiments.
CONCLUSIONS
Our results show that modification of NOTA as well as gallium chelation onto proteins, in casu somatropin, does not lead to a significantly changed pharmacokinetic profile at the blood-brain barrier.
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