Response of Endothelial Cells to Gelatin-Based Hydrogels

Abstract

The establishment of confluent endothelial cell (EC) monolayers on implanted materials has been identified as a concept to avoid thrombus formation but is a continuous challenge in cardiovascular device engineering. Here, material properties of gelatin-based hydrogels obtained by reacting gelatin with varying amounts of lysine diisocyanate ethyl ester were correlated with the functional state of hydrogel contacting venous EC (HUVEC) and HUVEC’s ability to form a monolayer on these hydrogels. The density of adherent HUVEC on the softest hydrogel at 37 °C (G’ = 1.02 kPa, E = 1.1 ± 0.3 kPa) was significantly lower (125 mm–1) than on the stiffer hydrogels (920 mm–1; G’ = 2.515 and 5.02 kPa, E = 4.8 ± 0.8 and 10.3 ± 1.2 kPa). This was accompanied by increased matrix metalloprotease activity (9 pmol·min–2 compared to 0.6 pmol·min–2) and stress fiber formation, while cell-to-cell contacts were comparable. Likewise, release of eicosanoids (e.g., prostacyclin release of 1.7 vs 0.2 pg·mL–1·cell–1) and the pro-inflammatory cytokine MCP-1 (8 vs <1.5 pg·mL–1·cell–1) was higher on the softer than on the stiffer hydrogels. The expressions of pro-inflammatory markers COX-2, COX-1, and RAGE were slightly increased on all hydrogels on day 2 (up to 200% of the control), indicating a weak inflammation; however, the levels dropped to below the control from day 6. The study revealed that hydrogels with higher moduli approached the status of a functionally confluent HUVEC monolayer. The results indicate the promising potential especially of the discussed gelatin-based hydrogels with higher G’ as biomaterials for implants foreseen for the venous system.

Establishment of an in vitro thrombogenicity test system with cyclic olefin copolymer substrate for endothelial layer formation

“…According to the Berg limit, unspecific protein adsorption is likely to occur above a critical water contact angle of 60–65°, while below this limit, unspecific protein adsorption is limited. [ 22 , 23 ] As the water contact angle of the COC is exactly in the range of the Berg limit, it remains to be investigated whether protein adsorption is promoted.…”

Protein-Based Hydrogels: Promising Materials for Tissue Engineering

“…Of note, gelatin's functional groups, including primary amine, carboxyl, and hydroxyl, enable its modification with various cross-linkers and therapeutic agents, making it an ideal candidate for tissue regeneration [166]. The hydrophobic amino acids of gelatin, such as tyrosine and proline, can be cross-linked using glutaraldehyde [171], diisocyanates [172], carbodiimides [173], and genipin [174]. Additionally, being thermo-responsive, gelatin can exhibit a reversible sol-gel transition property; indeed, the conversion from solution to gel occurs whenever the temperature drops, and this alteration can be reversed by raising the temperature of the combination to the physiological temperature.…”

Poly(2-Methoxyethyl Acrylate) (PMEA)-Coated Anti-Platelet Adhesive Surfaces to Mimic Native Blood Vessels through HUVECs Attachment, Migration, and Monolayer Formation

“…The formation of confluent EC monolayers on implanted materials has been identified as a method to avoid thrombus formation [28,40]. PMEA polymer analogs (PMEA, PMC3A, and PBA) and PMPC were coated on PET substrates to culture HUVECs and investigate HUVECs adhesion ability.…”

“…In contrast, the adhesion energy differed among the various interaction locations of the attached HUVEC, which may be due to the dissimilar surface interaction area and number of focal adhesion points. The different attachment behaviors of HUVECs on PMEA-analogous polymers depend on the hydration state, surface morphology, and stiffness of each polymer [35,40,42]. Generally, cells adhere to a polymeric surface via cell-binding proteins, such as fibronectin or fibrinogen, through integrin [43].…”