In addition, safranin O-fast green staining results (Fig. 7C) exhibited obvious demarcation between NP tissues and AF tissues with abundant proteoglycans and glycosaminoglycans in STZ-induced T1DM rats injected with oe-BMP7, while there was blurred demarcation between NP tissues and AF tissues with loss of proteoglycans and glycosaminoglycans in STZ-induced T1DM rats injected with oe-BMP7 and 4’MR. Here, BMP7 is linked to type 1 diabetes mellitus.