Abstract 11393: Computational Protein Design to Re-Engineer Stromal Cell-Derived Factor-1α (SDF) Generates a Supra-Efficient Angiogenic Polypeptide Analog
Background: After ischemic injury, cardiac secretion of the potent endothelial progenitor stem cell (EPC) chemokine SDF stimulates endogenous neovascularization and myocardial repair, a process insufficiently robust to repair major infarcts. Experimentally, exogenous administration of recombinant SDF enhances neovasculogenesis and cardiac function after MI. However, SDF has a short half-life, is bulky, and very expensive. Smaller analogs of SDF may provide translational advantages including enhanced stability and function, ease of synthesis, lower cost, and potential modulated delivery via engineered biomaterials. In this study, computational protein design was used to create a mathematically more efficient evolution of the native SDF protein.
Methods and Results: Protein structure modeling utilizing satisfaction of spatial restraints was used to engineer an SDF polypeptide analog (ESA) that combined the N-terminus (activation and binding) and C-terminus (extracellular stabilization) with a diproline residue to limit the conformational flexibility of the peptide backbone and generate an optimal three dimensional polypeptide configuration. EPCs in ESA gradient, assayed by Boyden chamber, showed significantly increased migration compared to both SDF and saline (ESA 567±74 cells/HPF vs SDF 438±46 p=0.037; vs Control 156±45 p=0.001). EPC receptor activation was evaluated by quantifying phosphorylated AKT. ESA had significantly greater pAKT levels than SDF and control (1.64±0.24 vs 1.26±0.187, p=0.01; vs. 0.95±0.08, p<0.001). Also, CD-1 mice (n=30) underwent LAD ligation and peri-infarct intramyocardial injection of ESA, SDF-1α, or saline. At 2 weeks, echocardiography demonstrated a significant gain in EF, CO, SV, and Fractional Area Change (FAC) in mice treated with ESA when compared to controls and significant improvement in FAC when compared to SDF treated mice. Angiogenic growth factor assays revealed a distinct increase in Angiopoietin 1 expression in the ESA and SDF treated hearts.
Conclusion: A novel re-engineered SDF polypeptide analog more efficiently induces EPC migration and improves post-MI cardiac function compared to native SDF protein, and thus offers a more clinically translatable neovasculogenic therapy.
- Cardiac surgery
- Endothelial progenitor cell
- Coronary microcirculation
- Myocardial revascularization
- © 2010 by American Heart Association, Inc.