Abstract: The present invention relates to an MG53 mutant, wherein the MG53 mutant is identical to the amino acid sequence of a wild-type MG53 except for at least one serine in the coiled-coil-SPRY region of the wild-type MG53, which is deleted and/or mutated into any other non-serine or non-threonine amino acid(s). The present invention also relates to a pharmaceutical composition comprising the MG53 mutant, a nucleic acid encoding the MG53 mutant, a method for preparing the MG53 mutant, use of the MG53 mutant in the manufacture of a medicament for treating heart diseases, diabetic cerebrovascular diseases, diabetic ocular complications, diabetic neuropathy, diabetic foot, kidney diseases, and diseases associated with cellular and/or tissue damage. In particular, the MG53 mutant of the present invention may avoid or reduce metabolic side effects, such as, insulin resistance, obesity, diabetes, hypertension, dyslipidemia, etc.