Synthesis and evaluation of ۹۹mTc-DOTA-ARA-۲۹۰ as potential SPECT tracer for targeting cardiac ischemic region

Objective(s): 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-۲۹۰) which is derived from the B-subunit of EPO. Materials and Methods: We designed and synthesized a modified DOTA-(Lys-Dabcyl۶, Phe۷)-ARA-۲۹۰ 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 Arg۶ and Ala۷, respectively; they were then investigated for the ability to detect ischemic cardiac imaging. DOTA-(Lys-Dabcyl۶,Phe۷)-ARA-۲۹۰ was labeled with technetium ۹۹m, and its radiochemical purity (RCP), stability in the presence of human serum and, specific bind to hypoxic H۹c۲ cells were evaluated. In vivo studies for biodistribution and SPECT scintigraphy were checked in a normal and cardiac ischemia rat model. Results: Radiolabeling purity was obtained more than ۹۶% by ITLC, and in vitro stability of the radiopeptide up to ۶ hr was ۸۵%. The binding of ۹۹mTc-ARA-۲۹۰ to hypoxic cells was remarkably higher than normoxic cells (۳ times higher than normoxic cells at ۱ hr). Biodistribution and SPECT imaging on the cardiac ischemic model showed that radiopeptide considerably accumulated in the ischemic region (cardiac ischemic-to-lung rate = ۳.۶۵ ID/g % at ۰.۵ hr).Conclusion: The results of studies, in vitro  and in vivo, indicated that ۹۹mTc-DOTA-(Lys-Dabcyl۶,Phe۷)-ARA-۲۹۰ could be an appropriate candidate for early diagnosis of cardiac ischemia.

کلیدواژه ها:

ARA-۲۹۰ ، Erythropoietin (EPO) ، Ischemia ، Molecular imaging ، Technetium-۹۹m