Effect of Charge and Molecular Weight on the Functionality of Gelatin Carriers for Corneal Endothelial Cell Therapy

Abstract

Cell transplantation strategies usually involve the use of supporting carrier materials because of the soft and fragile nature of these grafts. In this work, a cell-adhesive gelatin hydrogel carrier was fabricated to deliver cultivated human corneal endothelial cell (HCEC) sheets, which were harvested from thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted culture surfaces. The carrier disks, consisting of gelatins with a different isoelectric point (IEP = 5.0 and 9.0) and a molecular weight (MW) ranging from 3 to 100 kDa, were subjected to 16.6 kGy gamma irradiation for sterilization. The effect of IEP and MW of the raw gelatins (i.e., before irradiation) on the functionality of sterilized disks was studied by determinations of mechanical property, water content, dissolution degree, and cytocompatibility. Irrespective of the IEP of raw gelatin, hydrogel disks prepared with high MW (100 kDa) exhibited a greater tensile strength, lower water content, and slower dissolution rate than those made of low MW gelatin (8 and 3 kDa). From the investigation of cellular responses to the disks, the negatively charged gelatin (IEP = 5.0) groups were more cytocompatible when compared with their positively charged counterparts (IEP = 9.0) at the same MW (100 kDa). Additionally, in the negatively charged gelatin groups, only a slight increase in pro-inflammatory cytokine expression was observed with increasing MW of gelatin from 3 to 100 kDa. It is concluded that the gamma-sterilized hydrogel disks made from raw gelatins (IEP = 5.0, MW = 100 kDa) with appropriate dissolution degree and acceptable cytocompatibility are capable of providing stable mechanical support, making these carriers promising candidates for intraocular delivery of cultivated HCEC sheets.

Engineering Functional Epithelium for Regenerative Medicine and In Vitro Organ Models: A Review

“…107,108 There is substantial literature for the controlled delivery systems on the adhesion of gels and other structures such as microcapsules in the respiratory and digestive tract and these data can be used for optimizing cell carriers. 109 The carriers should either promote epithelial functions by themselves or act as facilitators for promoting the effects of mesenchymal cells on epithelial function.…”

Stabilization of collagen nanofibers with l-lysine improves the ability of carbodiimide cross-linked amniotic membranes to preserve limbal epithelial progenitor cells

“…Nevertheless, the HCE-2 cells exposed to the biological tissue membranes are less metabolically active when the l-lysine-pretreated concentration is increased to a sufficiently high level (ie, 30 mM). We have previously 43 For the test samples carrying either a positive or negative charge, the inhibition cell proliferation and decrease in cell viability are correlated with the relatively high charge density. As demonstrated by the aforementioned ninhydrin assays and zeta potential measurements, the presence of a large amount of positively charged amino acid residues in the AM pretreated with 30 mM l-lysine causes reduction in cell survival over a period of 3 days, which indicates that these biological tissue membranes may not be well tolerated in human corneal epithelial cultures.…”

Mussel-inspired human gelatin nanocoating for creating biologically adhesive surfaces

“…1,2 Gelatin coating is widely used for surface modification. Gelatin is a mixture of peptides and proteins produced by partial hydrolysis of collagen extracted from the skin, bone, and connective tissue of a number of different animals, including domesticated cattle, chicken, pigs, and fish.…”