Hepatoma-derived growth factor-2 is highly expressed during development and in spinal cord injury

Hepatoma‑derived growth factor‑2 (HDGF‑2) is expressed in neurons, astrocytes and oligodendrocytes of the adult mouse brain. However, it has remained elusive whether HDGF‑2 is expressed in the spinal cord and is involved in the its development and repair. In the present study, the expression of HDGF‑2 was investigated in rat spinal cords at different developmental stages and following spinal cord injury (SCI). Protein levels of HDGF‑2 were examined using western blot analysis, while the distribution pattern and cell populations of HDGF‑2 protein expression were characterized using immunohistochemistry. Western blot analysis demonstrated that the levels of HDGF‑2 protein expression were the greatest in the spinal cord on embryonic day 19, and were also highly expressed in rat spinal cords on post‑natal day 7 (P7); however, they were low at P14 and not detectable at two months. HDGF‑2 expression was significantly upregulated in the embryonic spinal cord and injured spinal cord. By contrast, the expression of HDGF‑2 was low in uninjured adult spinal cords. HDGF‑2 expression in the fetal rat spinal cord and injured spinal cord was significantly higher than that in uninjured adult spinal cord tissues (P<0.05). The number of cells positive for HDGF‑2 was 141±62, 107±33 and 92±18 at days 1, 21 and 45 following SCI, respectively, as opposed to 50±9 in uninjured rats, and a significant difference was identified between the different time‑points following SCI (P<0.01). In conclusion, the overexpression of HDGF‑2 in the embryonic spinal cord and injured spinal cord may be involved in fetal spinal cord development and repair of SCI, respectively.