Nerve growth factor modulates in vitro the expression and release of TGF-beta1 by amniotic membrane

To determinate the basal production of NGF and TGF-beta1 by amniotic membrane (AM) and to verify the presence of NGF receptors (trkA(NGFR) and p75(NTR)) in AM. Thereafter, to evaluate in an in vitro model if increasing concentrations of NGF are able to stimulate AM to produce and release TGF-beta1.

Immunohistochemistry, ELISA, in situ hybridization and PCR analysis for NGF, TGF-beta1, trkA(NGFR) and p75(NTR) were performed to study their presence in AM. Amniotic membranes were stimulated in vitro with increasing concentrations of NGF. After 24 h, the amount of TGF- beta1 in the AM tissue and in the culture medium was investigate.

AM expressed TGF-beta1, NGF, trkA(NGFR) and p75(NTR) mRNAs and proteins and released basal amounts of NGF and TGF-beta1 in the medium. Stimulation of AM by addition of NGF induced a significant (P<0.05) increase of TGF-beta1 mRNA/protein in AM tissue as well as a release of TGF-beta1 protein into the culture medium, in a dose-dependent fashion.

This study demonstrates that amniotic membrane releases basal amounts of NGF and TGF-beta1 and expresses NGF receptors . Moreover, the addition of NGF to the culture medium stimulates the amniotic membrane to significantly increase the production and release of TGF-beta1.