doi:10.3850/978-981-08-7615-9_TE01

ABSTRACT

Over the past few years, cell sheet engineering has been proposed as a novel strategy for regenerative medicine. Despite having a tissue-like architecture, the bioengineered corneal endothelial cell (CEC) sheets fabricated from thermo-responsive culture surfaces are usually fragile. To overcome the drawbacks associated with surgical manipulation, a simple stirring process combined with freeze-drying method was recently developed for the production of cross-linked porous gelatin hydrogels that can provide the support structure and improve the aqueous humor circulation. The purpose of this study was to further evaluate the influence of cross-linking degree on the delivery performance of gelatin carriers. After cross-linking with 1 mM 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) for different time periods, the porous gelatin samples with varying cross-linking degrees ranging from 0 to around 60% were obtained. It was found that smaller pore size, lower porosity, and larger superficial area were associated with increasing extent of cross-linking of the carrier discs. Although the hydrogels treated for short reaction time (i.e., below 6 h) had low resistance to initial nutrient permeation, these materials exhibited rapid swelling, implying a potential anterior segment tissue squeezing effect for use as intraocular implants. In addition, the delivery carriers with limited extent of cross-linking degraded too fast to be effective for retention of cell sheet grafts at the site of injury. By contrast, the gelatin samples with cross-linking degrees greater than 50% showed slower degradation rates and smaller porous structure, thereby possibly causing a significant inhibition of CEC proliferation. Cell sheet transfer studies demonstrated that the carrier discs with a high cross-linking degree (59.4 ± 1.3%) were more difficult to achieve stable cell attachment than their counterparts with a low cross-linking degree (48.3 ± 1.5%). Our findings suggest that among the cross-linked porous samples studied, 12 h is the best crosslinking reaction time for preparation of cell sheet carriers with suitable delivery performance.

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