Abstract

Our previous work identified a 12-amino acid peptide that targets the heart, termed cardiac targeting peptide (CTP). We now quantitatively assess the bio-distribution of CTP, show a clinical application with the imaging of the murine heart, and study its mechanisms of transduction. Bio-distribution studies of cyanine5.5-N-Hydroxysuccinimide (Cy5.5) labeled CTP were undertaken in wild-type mice. Cardiac targeting peptide was labeled with Technetium 99m (99mTc) using the chelator hydrazino-nicotinamide (HYNIC), and imaging performed using micro-single photon emission computerized tomography/computerized tomography (SPECT/CT). Human-induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMCs) were incubated with dual-labeled CTP, and imaged using confocal microscopy. TriCEPs technology was utilized to study the mechanism of transduction. Bio-distribution studies showed peak uptake of CTP at 15 min. 99mTc-HYNIC-CTP showed heart-specific uptake. Robust transduction of beating human iPSC-derived CMCs was seen. TriCEPs experiments revealed five candidate binding partners for CTP, with Kcnh5 being felt to be the most likely candidate as it showed a trend towards being competed out by siRNA knockdown. Transduction efficiency was enhanced by increasing extracellular potassium concentration, and with Quinidine, a Kcnh5 inhibitor, that blocks the channel in an open position. We demonstrate that CTP transduces the normal heart as early as 15 min. 99mTc-HYNIC-CTP targets the normal murine heart with substantially improved targeting compared with 99mTc Sestamibi. Cardiac targeting peptide’s transduction ability is not species limited and has human applicability. Cardiac targeting peptide appears to utilize Kcnh5 to gain cell entry, a phenomenon that is affected by pre-treatment with Quinidine and changes in potassium levels.

Details

Title
Cardiac Targeting Peptide, a Novel Cardiac Vector: Studies in Bio-Distribution, Imaging Application, and Mechanism of Transduction
Author
Zahid, Maliha 1 ; Feldman, Kyle S 1 ; Garcia-Borrero, Gabriel 1 ; Feinstein, Timothy N 1 ; Pogodzinski, Nicholas 1 ; Xu, Xinxiu 1 ; Yurko, Raymond 2 ; Czachowski, Michael 3 ; Wu, Yijen L 1 ; Mason, Neale S 3 ; Lo, Cecilia W 1 

 Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15201, USA 
 Peptide Synthesis Facility, University of Pittsburgh, Pittsburgh, PA 15201, USA 
 Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15201, USA 
First page
147
Publication year
2018
Publication date
2018
Publisher
MDPI AG
e-ISSN
2218273X
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2582796726
Copyright
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.