Study summary · research use only
Synthesis and evaluation of (99m)Tc-DOTA-ARA-290 as potential SPECT tracer for targeting cardiac ischemic region
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this study combining in vitro work with a rat model of cardiac ischemia, researchers synthesized a modified DOTA-(Lys-Dabcyl6, Phe7)-ARA-290 peptide and labeled it with technetium 99m as a potential SPECT imaging tracer. Radiolabeling purity was reported at more than 96% by ITLC, and in vitro stability of the radiopeptide up to 6 hr was 85%. Binding of 99mTc-ARA-290 to hypoxic H9c2 cells was reported as 3 times higher than to normoxic cells at 1 hr. In biodistribution and SPECT imaging in the cardiac ischemic rat model, the radiopeptide accumulated in the ischemic region, with a cardiac ischemic-to-lung ratio of 3.65 ID/g % at 0.5 hr. The authors describe the compound as a candidate for early cardiac ischemia detection imaging.
Abstract
Myocardial infarction caused by ischemia of heart tissue is the main reason for death worldwide; therefore, early detection can reduce mortality and treatment costs. Erythropoietin (EPO) has protection effects on ischemic tissue due to nonhematopoietic peptide (pHBSP; ARA-290) which is derived from the B-subunit of EPO. We designed and synthesized a modified DOTA-(Lys-Dabcyl6, Phe7)-ARA-290 using Fmoc solid-phase peptide synthesis strategies. To improve serum stability, Fmoc-Lys-(Dabcyl)-OH as lipophilic amino acid was synthesized along with Fmoc-Phe-OH which then were substituted with Arg6 and Ala7, respectively; they were then investigated for the ability to detect ischemic cardiac imaging. DOTA-(Lys-Dabcyl6,Phe7)-ARA-290 was labeled with technetium 99m, and its radiochemical purity (RCP), stability in the presence of human serum and, specific bind to hypoxic H9c2 cells were evaluated. In vivo studies for biodistribution and SPECT scintigraphy were checked in a normal and cardiac ischemia rat model. Radiolabeling purity was obtained more than 96% by ITLC, and in vitro stability of the radiopeptide up to 6 hr was 85%. The binding of 99mTc-ARA-290 to hypoxic cells was remarkably higher than normoxic cells (3 times higher than normoxic cells at 1 hr). Biodistribution and SPECT imaging on the cardiac ischemic model showed that radiopeptide considerably accumulated in the ischemic region (cardiac ischemic-to-lung rate = 3.65 ID/g % at 0.5 hr). The results of studies, in vitro and in vivo, indicated that 99mTc-DOTA-(Lys-Dabcyl6,Phe7)-ARA-290 could be an appropriate candidate for early diagnosis of cardiac ischemia.
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