Jeffrey Hubbell, Engineering Cytokines

Engineering Cytokines for Super-Affinity Binding to Matrix in Regenerative Medicine

In physiological situations of morphogenesis, cytokines exist in tight association with the extracellular matrix (ECM). The ECM sequesters cytokines, localizes them, and by association with adhesion molecules in the ECM modulates their signaling. Thus, physiological signaling from cytokines occurs primarily when the cytokines are interacting with the ECM. In therapeutic use of cytokines, however, this interaction and balance have not been respected; rather the cytokines
are merely injected or applied as soluble molecules, perhaps in controlled release forms. This has led to modest efficacy and substantial concerns on safety. Here, we will develop a protein engineering design for second-generation cytokines to lead to their super-affinity binding to ECM molecules in the targeted tissues; this would allow application to a tissue site to yield a tight association with ECM molecules there, turning the tissue itself into a reservoir for cytokine
sequestration and presentation. To accomplish this, we have undertaken preliminary work screening a library of cytokines for extraordinarily high affinity binding to a library of ECM molecules.

We have thereby discovered a small peptide domain within placental growth factor-2 (PlGF-2),namely PlGF-2123-144, that displays super-affinity for a number of ECM proteins. Also in preliminary work, we have demonstrated that recombinant fusion of this domain to low-affinity binding cytokines, considering as examples vascular endothelial growth factor-A(VEGF-A), platelet-derived growth factor-BB (PDGF-BB) and bone morphogenetic protein-2(BMP-2), confers super-
affinity binding to ECM molecules and accentuates their functionality in vivo in tissue repair models. In the proposed project, based on this preliminary data, we will push forward this protein engineering design, pursuing super -affinity variants of VEGF-A and PDGF -BB (in hand, from the preliminary work), transforming growth factor -β3 (TGF-β3), CX chemokine ligand 11 (CXCL11), CXchemokine ligand 12 (CXCL12, also know as stromal cell-derived factor-1, SDF-1)and fibroblast growth factor-18 (FGF-18). We will pursue these second-generation engineered cytokine variants in models of chronic skin wound repair (engineered variant VEGF-A and PDGF-BB), skin scar reduction (engineered variant TGF-β3 and CXCL11), stemcell recruitment to ischemic cardiac muscle (engineered variant CXCL12) and osteoarthritic cartilage repair (engineered variant FGF-18).

Host institution: EPFL
Project acronym: Cytrix
Domain: Life Sciences