Hepatocytes exhibit constant metabolic activity on carboxymethylcellulose-based hydrogel with high phenolic hydroxy group content

Control of cellular adhesiveness in hyaluronic acid-based hydrogel through varying degrees of phenol moiety cross-linking

Current hyaluronic acid-based hydrogels often cause cytotoxicity to encapsulated cells and lack the adhesive property required for effective biomedical and tissue engineering applications. Provision of the cell-adhesive surface is an important requirement to improve its biocompatibility. An aqueous solution of hyaluronic acid possessing phenolic hydroxyl (HA-Ph) moieties is gellable via a horseradish peroxidase (HRP)-catalyzed oxidative cross-linking reaction. This study evaluates the effect of different degrees of cross-linked Ph moieties on cellular adhesiveness and proliferation on the resultant enzymatically cross-linked HA-Ph hydrogels. Mechanical characterization demonstrated that the compression force of engineered hydrogels could be tuned in the range of 0.05-35 N by changing conjugated Ph moieties in the precursor formulation. The water contact angle and water content show hydrophobicity of hydrogels increased with increasing content of cross-linked Ph groups. The seeded mouse embryo fibroblast-like cell line and human cervical cancer cell line, on the HA-Ph hydrogel, proved cell attachment and spreading with a high content of cross-linked Ph groups. The HA-Ph with a higher degree of Ph moieties shows the maximum degree of cell adhesion, spreading, and proliferation which presents this hydrogel as a suitable biomaterial for biomedical and tissue engineering applications.

Cell-selective encapsulation in hydrogel sheaths via biospecific identification and biochemical cross-linking

Selective encapsulation of a particular cell population from heterogeneous cell populations has potential applications such as studies in cell-to-cell communication, regenerative medicine, and cell therapies. However, there are no versatile methods for realizing this. Here we report a method based on biospecific identification of the target cells through antigen-antibody reaction and subsequent enzymatic hydrogel sheath formation on the cell surfaces by horseradish peroxidase (HRP). Human hepatoma cell line HepG2 cells were selectively encapsulated in alginate-based hydrogel sheath from the mixture with mouse embryo fibroblast-like cell line 10T1/2 fibroblasts using anti-human CD326 antibody conjugated with HRP. The viability of the encapsulated cells was 93%. The cells released at 6 days of the encapsulation by degrading the sheath using alginate lyase grew almost the same as those free from encapsulation. The versatility of the method was confirmed using another antibody, cells, and hydrogel sheath material: Only human vein endothelial cells were encapsulated in gelatin-based hydrogel sheath from the mixture with 10T1/2 fibroblasts using anti-human CD31 antibody conjugated with HRP. The cell-selective encapsulation was also achieved by a system using a primary antibody with a secondary antibody conjugated with HRP.