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Chengxin Zhou, James Chodosh, Claes H Dohlman, Eleftherios I Paschalis; Role of titanium surface topography in regulation of corneal cell growth, patterning, and matrix deposition. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1126.
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© ARVO (1962-2015); The Authors (2016-present)
Medigrade titanium (Ti) is used in Boston Keratorposthesis (BK-Pro) backplates. However, the interaction between corneal cells and different Ti surface topographies (ST) has never been studied. This study was undertaken to assess the effect of Ti-ST in human corneal cells.
Equally hydrophilic Ti disks with different STs, ranging from Grade 0 (0.175 RMS; smoothest) to Grade 3 (4.413 RMS; roughest) were placed on the bottom of 24-wells and cultured with human corneal/limbal epithelial (HCLE), stromal fibroblasts (HCFs), endothelial cells and HeLa cells (n=3; for each cell line). Cell cytotoxicity and proliferation assays were performed at Day 2, 3, and 5. HCFs were also cultured for 6 weeks in serum media + ascorbic acid, w/wt TGFβ1, and tested for collagen deposition, cell morphology and α-smooth muscle actin (αSMA) expression.
None of the Ti Grades showed cell cytotoxicity (p>0.05, one-way ANOVA). However, Grade 2 and 3 caused significant inhibition of HCLE and HCF cell proliferation at Day 3 and 5 compared to Grade 0. At 6 weeks of HCF culture in serum media, all Ti Grades had equal cell densities and did not induce myofibroblast transformation. Yet Grade 3 had significantly less collagen deposition compared to Grade 0 (p<0.05). Grade 0 provided HCFs better cell adhesion, remarkable directionality in cell alignment and had parallel aligned, fibrillar collagen meshwork, while Grade 3 had randomly aligned cells and collagen deposits.<br /> <br /> Addition of TGFβ1 in HCF culture caused marked myofibroblast transformation and more collagen-V secretion in all Grades. Transformed HCFs on Grade 3 had higher αSMA expression, less collagen deposition and randomly oriented collagen fibrils as compared to those on Grade 0 which had parallel aligned collagen fibrils.
To our knowledge, this is the first study suggesting that Ti-ST plays an important regulatory role in corneal cell phenotype. The effect is tissue-dependent, varying across different corneal stratums, with epithelium being more impacted. Contrary to the established paradigm in Orthopedics, smooth Ti surface better facilitates corneal cell proliferation, matrix deposition, and reduces αSMA expression under TGFβ1 stimulation as compared to rough Ti surface. These results suggest that BK-Pro Ti may benefit from tissue-targeted surface modification that promotes desired biological responses in the cornea.
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