Basic fibroblast growth factor in human tear fluid: detection of another growth factor.

BACKGROUND

Topical application of various growth factors have shown promising experimental data in speeding up corneal wound healing. Similar effects have been reported for another group of proteins, fibroblast growth factors (FGFs). One of them, basic FGF (bFGF), stimulates the proliferation of cells of mesodermal as well as of neuroectodermal origin and is highly angiogenic. The aim of the present study was to investigate the presence of bFGF in human tear fluid.

METHODS

After establishing an advanced enzyme-linked immunosorbent assay technique, tear fluid was collected from 15 healthy individuals before and after stimulation of reflex tearing.

RESULTS

In none of the tear fluid samples collected prior to induction of reflex tearing could FGF be detected. Of the 15 samples collected during reflex tearing, six (40%) contained measurable amounts of bFGF. The amount of bFGF appeared to decrease with increasing tear fluid flow, suggesting a dilution effect.

CONCLUSION

This study gives strong evidence that bFGF, as previously shown for epidermal growth factor and transforming growth factor-alpha, may occur in human tear fluid of healthy individuals after induction of reflex tearing and, in very low concentrations, under normal conditions. Whether bFGF can to be considered a constant component of tear fluid, however, remains to be investigated.