Increased expression of heparanase in osteogenic differentiation of rat marrow stromal cells

Heparanase (HPSE) is a type of endoglycosidase that decomposes the heparan sulfate (HS) lateral chains of heparan sulfate proteoglycans (HSPGs), releases related growth factors and participates in angiogenesis and bone formation. HPSE is expressed in osteoblasts and is involved in fracture healing. However, the role of HPSE in osteogenic differentiation requires in-depth investigation. To investigate the expression of HPSE in the osteogenic differentiation of rat marrow stromal cells (MSCs), the protein and mRNA expression levels of HPSE on days 0, 1, 3, 7, 10, 14 and 21 of osteogenic differentiation of MSCs in 2- and 10-month-old rats were detected using western blotting and reverse transcription-polymerase chain reaction (RT-PCR), respectively. From the third day of osteogenic differentiation onwards, all HPSE protein and mRNA expression levels in 2-month-old rats were significantly increased compared with basal levels (days 0 and 1; P<0.05). The protein and mRNA expression levels reached a peak on days 10 and 14, respectively, followed by a gradual decline. The same pattern was observed in 10-month-old rats; however, when compared with with basal levels, the differences were not statistically significant (P>0.05). The protein and mRNA levels of HPSE in the 2-month-old rats were significantly higher compared with the respective levels in the 10-month-old rats (P<0.05). HPSE is involved in the osteogenic differentiation of rat MSCs. The protein and mRNA expression levels of HPSE in aged rats are weaker compared with those in young rats, which may be related to the declined osteogenic differentiation ability.