Antifibrotic effects of tocotrienols on human Tenon’s fibroblasts
- 102 Downloads
To compare the antifibrotic effect of vitamin E isoforms α-, γ-, and δ-tocotrienol on human Tenon’s fibroblasts (hTf) to the antimetabolite mitomycin C.
Antifibrotic effects of α- (40, 60, 80, 100, and 120 μM), γ- (10, 20, 30, and 40 μM) and δ-tocotrienol (10, 20, 30, and 40 μM) on hTf cultures were evaluated by performing proliferation, migration and collagen synthesis assays. Whereas for vitamin E the exposure time was set to 7 days to mimic subconjunctival application, cultures were exposed only 5 min to mitomycin C 100 μg/ml to mimic intraoperative administration. Cell morphology (phase contrast microscopy) as an assessment for cytotoxicity and cell density by measuring DNA content in a fluorometric assay to determine proliferation inhibition was performed on day 0, 4, and 7. Migration ability and collagen synthesis of fibroblasts were measured.
All tested tocotrienol isoforms were able to significantly inhibit hTf proliferation in a dose-dependent manner (maximal inhibitory effect without relevant morphological changes at day 4 for α-tocotrienol 80 μM with 36.7% and at day 7 for α-tocotrienol 80 μM with 42.6% compared to control). Degenerative cell changes were observed in cultures with concentrations above 80 μM for α- and above 30 μM for γ- and δ-tocotrienol. The highest collagen synthesis inhibition has been found with 80 µM α-tocotrienol (62.4%) and no significant inhibition for mitomycin C (2.5%). Migration ability was significantly reduced in cultures exposed to 80 µM α- and 30 µM γ-tocotrienol (inhibition of 82.2% and 79.5%, respectively, compared to control) and also after mitomycin C treatment (60.0%). Complete growth inhibition without significant degenerative cell changes could only be achieved with mitomycin C.
In vitro, all tested tocotrienol isoforms were able to inhibit proliferation, migration and collagen synthesis of human Tenon’s fibroblasts and therefore may have the potential as an anti-scarring agent in filtrating glaucoma surgery.
KeywordsVitamin E Tocotrienol Antifibrotic effect Tenon’s fibroblast Filtrating glaucoma surgery Mitomycin C
The authors thank A. Azzi, Vascular Biology Laboratory at Tufts University, Washington, for his critical review of the manuscript.
Conflicts of interest
Tappeiner C: none; Meyenberg A: none, Goldblum D: none; Mojon D: none; Zingg JM: none; Nesaretnam K: employee of the Malaysian Palm Oil Board, no proprietary interests; Kilchenmann M: none; Frueh BE: none
- 11.Wilkins M, Indar A, Wormald R (2005) Intra-operative mitomycin C for glaucoma surgery. Cochrane Database Syst Rev, 2005(4): p. CD002897Google Scholar
- 14.Tasinato A et al (1995) d-alpha-tocopherol inhibition of vascular smooth muscle cell proliferation occurs at physiological concentrations, correlates with protein kinase C inhibition, and is independent of its antioxidant properties. Proc Natl Acad Sci USA 92(26):12190–12194CrossRefPubMedGoogle Scholar
- 22.Lama PJ, Fechtner RD (2003) Antifibrotics and wound healing in glaucoma surgery. Surv Ophthalmol 48(3):314–346Google Scholar
- 27.Chang PN et al (2009) Evidence of gamma-tocotrienol as an apoptosis-inducing, invasion-suppressing, and chemotherapy drug-sensitizing agent in human melanoma cells. Nutr Cancer 61(3):357–366Google Scholar
- 28.Inokuchi H et al (2003) Anti-angiogenic activity of tocotrienol. Biosci Biotechnol Biochem 67(7):1623–1627Google Scholar
- 30.Weng-Yew W et al (2009) Suppression of tumor growth by palm tocotrienols via the attenuation of angiogenesis. Nutr Cancer 61(3):367–373Google Scholar