An isolated antibody specific for MMP9 or an antigen-binding fragment thereof, wherein said antibody or fragment thereof comprises: (i) a heavy chain variable region comprising an amino acid sequence of SEQ ID NO: 11 or a variant of SEQ ID NO: 11 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:11: N 54 Q, N 54 R, N 54 K, N 54 H, D 62 E, S 63 T, M 116 I, D 88 A and V 93 L and (ii) further comprising a light chain variable region selected from the following group: SEQ ID NO: 24, or a variant of SEQ ID NO: 24 wherein the amino acid at position 107 of SEQ ID NO:24 is substituted with the substitution: V 107 L; SEQ ID NO: 67, or a variant of SEQ ID NO: 67 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions: V 45 L, V 70 A and V 107 L; SEQ ID NO: 29, or a variant of SEQ ID NO: 29 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:29: RsA, V 18 I, L 49 M, T 62 N, L 81 Q, and A 83 E; and SEQ ID NO: 69, or a variant of SEQ ID NO: 69 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:69: RsA, V 18 I, L 49 M, T 62 N, L 81 Q, A 83 E and FssY. (i) a heavy chain variable region comprising an amino acid sequence of SEQ ID NO: 11 or a variant of SEQ ID NO: 11 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:11: N 54 Q, N 54 R, N 54 K, N 54 H, D 62 E, S 63 T, M 116 I, D 88 A and V 93 L and (ii) further comprising a light chain variable region selected from the following group: SEQ ID NO: 24, or a variant of SEQ ID NO: 24 wherein the amino acid at position 107 of SEQ ID NO:24 is substituted with the substitution: V 107 L; SEQ ID NO: 67, or a variant of SEQ ID NO: 67 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions: V 45 L, V 70 A and V 107 L; SEQ ID NO: 29, or a variant of SEQ ID NO: 29 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:29: RsA, V 18 I, L 49 M, T 62 N, L 81 Q, and A 83 E; and SEQ ID NO: 69, or a variant of SEQ ID NO: 69 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:69: RsA, V 18 I, L 49 M, T 62 N, L 81 Q, A 83 E and FssY. SEQ ID NO: 24, or a variant of SEQ ID NO: 24 wherein the amino acid at position 107 of SEQ ID NO:24 is substituted with the substitution: V 107 L; SEQ ID NO: 67, or a variant of SEQ ID NO: 67 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions: V 45 L, V 70 A and V 107 L; SEQ ID NO: 29, or a variant of SEQ ID NO: 29 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:29: RsA, V 18 I, L 49 M, T 62 N, L 81 Q, and A 83 E; and SEQ ID NO: 69, or a variant of SEQ ID NO: 69 wherein at least one amino acid is substituted by a different amino acid selected among the following substitutions in the sequence of SEQ ID NO:69: RsA, V 18 I, L 49 M, T 62 N, L 81 Q, A 83 E and FssY.