The invention pertains to polypeptide variants with increased heparin-binding ability. Increased heparin-binding ability is achieved by addition, insertion, and/or substitution of an amino acid sequence X.sub.1X.sub.2X.sub.3X.sub.4X.sub.5X.sub.6 (SEQ ID NO. 1 or NO.2). Polypeptide variants according to the invention are particularly suited for stimulation of chondrogenesis, osteogenesis, and wound healing. The invention also pertains to amino acid molecules that encode said polypeptide variants, host cells containing said nucleic acid molecules, and processes for producing the polypeptide variants.