A fusion protein is described, comprising a first N-terminal signal peptide sequence, a second peptide sequence C-terminal to the signal peptide sequence, and a third peptide sequence C-terminal to the second peptide sequence; wherein one of the second peptide sequence and the third peptide sequence is an RdCVF-short peptide sequence and the other is a hydrophilic peptide sequence. After translation the signal peptide is cleaved, leaving a fusion protein comprising the second peptide sequence and the third peptide sequence minus the signal peptide. Also described are nucleic acids and expression vectors encoding the fusion protein, cells comprising the nucleic acid or expression vector, as well as methods of treatment and uses of the fusion protein, nucleic acid, and expression vector. The fusion protein can be produced in vitro by culturing the cells of this invention under conditions allowing for expression and secretion of the encoded fusion protein, and isolating the fusion protein from the cell culture.