Effect of Harderian gland-derived growth factor on the growth of cornea stromal cells

To investigate the physiological role of Harderian gland-derived growth factor (HGDGF), the effects of HGDGF and various other growth factors on the growth of cultured guinea pig cornea stromal cells were examined. HGDGF increased the incorporation of [3H]thymidine to 150% of the control (5% fetal calf serum). The combination of HGDGF with fibroblast growth factors (FGFs) or platelet-derived growth factor enhanced the cell growth over that of either growth factor alone, increasing the incorporation of [3H]thymidine to 180 and 190% of the control, respectively. The combination of HGDGF with transforming growth factor (TGF-beta) decreased the growth to 60% of the control, and epidermal growth factor had no effect on the activity of HGDGF. The growth-stimulating activity of HGDGF was inhibited by suramin in a different manner from that of FGFs. These findings suggest that HGDGF binds a specific cell-surface receptor and plays a role in the repair of injured parts of the cornea and in the maintenance of the cornea stromal cells.