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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

Scanning electron micrographs of the B. mori silk fibroin (BMSF) membranes. Physical appearance of non-treated (a–c), PEG-treated (d–g), and genipin-crosslinked PEG-treated (h–j) fibroin membranes. (a,d,h) Gross appearance of dried membranes after removal from the casting plate. Images of surfaces (b,e,i), cross-sections (c,f,j) and the edge of the PEG-treated membrane (g).
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jfb-06-00345-f001: Scanning electron micrographs of the B. mori silk fibroin (BMSF) membranes. Physical appearance of non-treated (a–c), PEG-treated (d–g), and genipin-crosslinked PEG-treated (h–j) fibroin membranes. (a,d,h) Gross appearance of dried membranes after removal from the casting plate. Images of surfaces (b,e,i), cross-sections (c,f,j) and the edge of the PEG-treated membrane (g).

Mentions: BMSF membranes of ca. 3 µm or ca. 6 µm in thickness were produced on a casting table. Upon addition of PEG with MW of 300 Da, at a PEG/fibroin weight ratio of 2, the thickness of the resulting membranes almost doubled. While the non-treated fibroin membranes were easy to peel off from the casting plate and to handle (Figure 1a), the PEG-treated membranes were fragile and difficult to remove without breaking them (Figure 1d).


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)

Scanning electron micrographs of the B. mori silk fibroin (BMSF) membranes. Physical appearance of non-treated (a–c), PEG-treated (d–g), and genipin-crosslinked PEG-treated (h–j) fibroin membranes. (a,d,h) Gross appearance of dried membranes after removal from the casting plate. Images of surfaces (b,e,i), cross-sections (c,f,j) and the edge of the PEG-treated membrane (g).
© Copyright Policy
Related In: Results  -  Collection

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

jfb-06-00345-f001: Scanning electron micrographs of the B. mori silk fibroin (BMSF) membranes. Physical appearance of non-treated (a–c), PEG-treated (d–g), and genipin-crosslinked PEG-treated (h–j) fibroin membranes. (a,d,h) Gross appearance of dried membranes after removal from the casting plate. Images of surfaces (b,e,i), cross-sections (c,f,j) and the edge of the PEG-treated membrane (g).
Mentions: BMSF membranes of ca. 3 µm or ca. 6 µm in thickness were produced on a casting table. Upon addition of PEG with MW of 300 Da, at a PEG/fibroin weight ratio of 2, the thickness of the resulting membranes almost doubled. While the non-treated fibroin membranes were easy to peel off from the casting plate and to handle (Figure 1a), the PEG-treated membranes were fragile and difficult to remove without breaking them (Figure 1d).

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