Abstract Body: Background:
Lipid-based drug delivery systems have significantly improved therapeutic cargo transport. However, achieving efficient and selective cardiac targeting remains a challenge. Cobalt porphyrin-phospholipid (CoPoP) enables the stable functionalization of liposomes by anchoring polyhistidine-tagged proteins and peptides. While CoPoP has been used in vaccine development, its potential for targeted drug delivery remains largely unexplored. We hypothesized that conjugating CoPoP liposomes with a cardiomyocyte-targeting peptide (CMP) would enhance their selective uptake by cardiomyocytes.
Methods:
A CMP peptide (WLSEAGPVVTVRALRGTGSW) was conjugated to CoPoP liposomes via polyhistidine-mediated cobalt chelation, leveraging a Co(II) to Co(III) transition for improved retention and stability. Nanoparticle tracking analysis was conducted to characterize liposome size and concentration. Cellular uptake of CoPoP liposomes was quantified in dose-response studies using AC16 cardiomyocytes (CMs) and normal human dermal fibroblasts (NHDFs) to evaluate specificity and dose dependency. Metabolic activity was assessed via a MTT assay to determine cytotoxicity.
Results:
Flow cytometry analysis revealed a significant, dose-dependent uptake of CMP-CoPoP in AC16 cardiomyocytes across concentrations from 0.25 to 2 µg/mL, confirming targeted interaction (p < 0.0001, R² = 0.7270, linear regression). In contrast, control-CoPoP and reverse CMP-CoPoP showed no significant uptake (p > 0.05), indicating specificity for the targeting peptide. At the highest concentration (2 µg/mL), CMP-CoPoP uptake in CMs was more than four times higher than in NHDFs, further demonstrating cell-type specificity (p = 0.01, unpaired t-test). Additionally, MTT assays confirmed no cytotoxic effects, as metabolic activity remained comparable to untreated controls across all groups.
Conclusion:
CMP-functionalized CoPoP liposomes demonstrate selective and efficient cardiomyocyte uptake without cytotoxicity, highlighting their potential as a targeted drug delivery platform for cardiac therapies.