Fig. 1

The concept of charge-based targeting of cartilage by using cationic peptide carrier (CPC) to deliver a pro-anabolic growth factor, IGF-1. A CPC +14N is comprised of 14 positively charged arginine (R) residues symmetrically distributed along the peptide length with hydrophilic asparagine (N) used as spacers. Its hydrophilic property minimizes its competitive binding within the synovial fluid. CPC-IGF-1 can rapidly penetrate through the full thickness of cartilage creating a drug depot to provide therapeutic drug doses over several days. B IGF-1 promotes chondrocyte proliferation, proteoglycan synthesis, and cell survival by activating the IGF-1 receptor. IGF-1 also suppresses IL-1-induced catabolism by downregulating the NF-kB pathway