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Treatment of Silk Fibroin with Poly(ethylene glycol) for the Enhancement of Corneal Epithelial Cell Growth.

Suzuki S, Dawson RA, Chirila TV, Shadforth AM, Hogerheyde TA, Edwards GA, Harkin DG - J Funct Biomater (2015)

Bottom Line: The resulting membranes were thoroughly characterized and compared to the non-treated membranes.The crosslinking with genipin did not induce a significant improvement in mechanical properties.The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes.

View Article: PubMed Central - PubMed

Affiliation: Queensland Eye Institute, South Brisbane, Queensland 4101, Australia. shuko.suzuki@qei.org.au.

ABSTRACT
A silk protein, fibroin, was isolated from the cocoons of the domesticated silkworm (Bombyx mori) and cast into membranes to serve as freestanding templates for tissue-engineered corneal cell constructs to be used in ocular surface reconstruction. In this study, we sought to enhance the attachment and proliferation of corneal epithelial cells by increasing the permeability of the fibroin membranes and the topographic roughness of their surface. By mixing the fibroin solution with poly(ethylene glycol) (PEG) of molecular weight 300 Da, membranes were produced with increased permeability and with topographic patterns generated on their surface. In order to enhance their mechanical stability, some PEG-treated membranes were also crosslinked with genipin. The resulting membranes were thoroughly characterized and compared to the non-treated membranes. The PEG-treated membranes were similar in tensile strength to the non-treated ones, but their elastic modulus was higher and elongation lower, indicating enhanced rigidity. The crosslinking with genipin did not induce a significant improvement in mechanical properties. In cultures of a human-derived corneal epithelial cell line (HCE-T), the PEG treatment of the substratum did not improve the attachment of cells and it enhanced only slightly the cell proliferation in the longer term. Likewise, primary cultures of human limbal epithelial cells grew equally well on both non-treated and PEG-treated membranes, and the stratification of cultures was consistently improved in the presence of an underlying culture of irradiated 3T3 feeder cells, irrespectively of PEG-treatment. Nevertheless, the cultures grown on the PEG-treated membranes in the presence of feeder cells did display a higher nuclear-to-cytoplasmic ratio suggesting a more proliferative phenotype. We concluded that while the treatment with PEG had a significant effect on some structural properties of the B. mori silk fibroin (BMSF) membranes, there were minimal gains in the performance of these materials as a substratum for corneal epithelial cell growth. The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes.

No MeSH data available.


Related in: MedlinePlus

Quantitative comparison of the tensile characteristics of non-treated (1), PEG-treated (2) and genipin-crosslinked PEG-treated (3) fibroin membranes. (a) Young’s modulus; (b) Ultimate tensile strength; (c) Elongation at break. Bars represents mean ± standard error of the mean (n = 6). An asterisk indicates that the difference is statistically significant (p < 0.05).
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jfb-06-00345-f004: Quantitative comparison of the tensile characteristics of non-treated (1), PEG-treated (2) and genipin-crosslinked PEG-treated (3) fibroin membranes. (a) Young’s modulus; (b) Ultimate tensile strength; (c) Elongation at break. Bars represents mean ± standard error of the mean (n = 6). An asterisk indicates that the difference is statistically significant (p < 0.05).

Mentions: The results of mechanical testing (Figure 4) indicated important differences between certain tensile characteristics of the three types of membranes. Although the ultimate strength values were similar for all samples, the elastic moduli of the PEG-treated membranes were significantly higher than those of the non-treated membranes, while their elongation at break was significantly lower. This can be a consequence of increased rigidity due to higher proportion of β-sheet conformations induced by the treatment with PEG, an assumption strongly suggested by the infrared spectrometric analysis. Rather unexpectedly, the crosslinking did not improve the tensile strength of the PEG-treated membranes.


Treatment of Silk Fibroin with Poly(ethylene glycol) for the Enhancement of Corneal Epithelial Cell Growth.

Suzuki S, Dawson RA, Chirila TV, Shadforth AM, Hogerheyde TA, Edwards GA, Harkin DG - J Funct Biomater (2015)

Quantitative comparison of the tensile characteristics of non-treated (1), PEG-treated (2) and genipin-crosslinked PEG-treated (3) fibroin membranes. (a) Young’s modulus; (b) Ultimate tensile strength; (c) Elongation at break. Bars represents mean ± standard error of the mean (n = 6). An asterisk indicates that the difference is statistically significant (p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493516&req=5

jfb-06-00345-f004: Quantitative comparison of the tensile characteristics of non-treated (1), PEG-treated (2) and genipin-crosslinked PEG-treated (3) fibroin membranes. (a) Young’s modulus; (b) Ultimate tensile strength; (c) Elongation at break. Bars represents mean ± standard error of the mean (n = 6). An asterisk indicates that the difference is statistically significant (p < 0.05).
Mentions: The results of mechanical testing (Figure 4) indicated important differences between certain tensile characteristics of the three types of membranes. Although the ultimate strength values were similar for all samples, the elastic moduli of the PEG-treated membranes were significantly higher than those of the non-treated membranes, while their elongation at break was significantly lower. This can be a consequence of increased rigidity due to higher proportion of β-sheet conformations induced by the treatment with PEG, an assumption strongly suggested by the infrared spectrometric analysis. Rather unexpectedly, the crosslinking did not improve the tensile strength of the PEG-treated membranes.

Bottom Line: The resulting membranes were thoroughly characterized and compared to the non-treated membranes.The crosslinking with genipin did not induce a significant improvement in mechanical properties.The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes.

View Article: PubMed Central - PubMed

Affiliation: Queensland Eye Institute, South Brisbane, Queensland 4101, Australia. shuko.suzuki@qei.org.au.

ABSTRACT
A silk protein, fibroin, was isolated from the cocoons of the domesticated silkworm (Bombyx mori) and cast into membranes to serve as freestanding templates for tissue-engineered corneal cell constructs to be used in ocular surface reconstruction. In this study, we sought to enhance the attachment and proliferation of corneal epithelial cells by increasing the permeability of the fibroin membranes and the topographic roughness of their surface. By mixing the fibroin solution with poly(ethylene glycol) (PEG) of molecular weight 300 Da, membranes were produced with increased permeability and with topographic patterns generated on their surface. In order to enhance their mechanical stability, some PEG-treated membranes were also crosslinked with genipin. The resulting membranes were thoroughly characterized and compared to the non-treated membranes. The PEG-treated membranes were similar in tensile strength to the non-treated ones, but their elastic modulus was higher and elongation lower, indicating enhanced rigidity. The crosslinking with genipin did not induce a significant improvement in mechanical properties. In cultures of a human-derived corneal epithelial cell line (HCE-T), the PEG treatment of the substratum did not improve the attachment of cells and it enhanced only slightly the cell proliferation in the longer term. Likewise, primary cultures of human limbal epithelial cells grew equally well on both non-treated and PEG-treated membranes, and the stratification of cultures was consistently improved in the presence of an underlying culture of irradiated 3T3 feeder cells, irrespectively of PEG-treatment. Nevertheless, the cultures grown on the PEG-treated membranes in the presence of feeder cells did display a higher nuclear-to-cytoplasmic ratio suggesting a more proliferative phenotype. We concluded that while the treatment with PEG had a significant effect on some structural properties of the B. mori silk fibroin (BMSF) membranes, there were minimal gains in the performance of these materials as a substratum for corneal epithelial cell growth. The reduced mechanical stability of freestanding PEG-treated membranes makes them a less viable choice than the non-treated membranes.

No MeSH data available.


Related in: MedlinePlus