Hydrogel is in the spotlight as a useful biomaterial in the field of drug delivery and tissue engineering due to its similar biological properties to a native extracellular matrix (ECM). Herein, we proposed a ternary hydrogel of gellan gum (GG), silk fibroin (SF), and chondroitin sulfate (CS) as a biomaterial for cartilage tissue engineering. The hydrogels were fabricated with a facile combination of the physical and chemical crosslinking method. The purpose of this study was to find the proper content of SF and GG for the ternary matrix and confirm the applicability of the hydrogel in vitro and in vivo. The chemical and mechanical properties were measured to confirm the suitability of the hydrogel for cartilage tissue engineering. The biocompatibility of the hydrogels was investigated by analyzing the cell morphology, adhesion, proliferation, migration, and growth of articular chondrocytes-laden hydrogels. The results showed that the higher proportion of GG enhanced the mechanical properties of the hydrogel but the groups with over 0.75% of GG exhibited gelling temperatures over 40 °C, which was a harsh condition for cell encapsulation. The 0.3% GG/3.7% SF/CS and 0.5% GG/3.5% SF/CS hydrogels were chosen for the in vitro study. The cells that were encapsulated in the hydrogels did not show any abnormalities and exhibited low cytotoxicity. The biochemical properties and gene expression of the encapsulated cells exhibited positive cell growth and expression of cartilage-specific ECM and genes in the 0.5% GG/3.5% SF/CS hydrogel. Overall, the study of the GG/SF/CS ternary hydrogel with an appropriate content showed that the combination of GG, SF, and CS can synergistically promote articular cartilage defect repair and has considerable potential for application as a biomaterial in cartilage tissue engineering.
The
cellular transplantation approach to treat damaged or diseased
retina is limited because of poor survival, distribution, and integration
of cells after implantation to the sub-retinal space. To overcome
this, it is important to develop a cell delivery system. In this study,
a ternary hydrogel of gelatin (Ge)/gellan gum (GG)/glycol chitosan
(CS) is suggested as a cell carrier for retinal tissue engineering
(TE). Physicochemical properties such as porosity, swelling, sol fraction,
and weight loss were measured. The mechanical study was performed
with compressive strength and viscosity to confirm applicability in
retinal TE. An in vitro experiment was carried out
by encapsulating ARPE-19 in the designed hydrogel to measure viability
and expression of retinal pigment epithelium-specific proteins and
genes. The results showed that the ternary hydrogel system improves
the mechanical properties and stability of the composite. Cell growth,
survival, adhesion, and migration were enhanced as the CS was incorporated
into the matrix. In particular, real-time polymerase chain reaction
analysis showed a markedly improved specific gene expression rate
in the Ge/GG/CS. Therefore, it is expected that the ternary system
suggested in this study can be used as a promising material for retinal
TE.
In
this study, dopamine-functionalized gellan gum (DFG) hydrogel
was prepared as a carrier for retinal pigment epithelium (RPE) cell
delivery via a carbodiimide reaction. The carboxylic
acid of gellan gum (GG) was replaced with catechol in a 21.3% yield,
which was confirmed by NMR. Sol fraction and weight loss measurements
revealed that dopamine improved degradability in the GG hydrogel.
Measurements of the viscosity, injection force, and compressibility
also showed that dopamine-functionalized GG hydrogels had more desirable
rheological/mechanical properties for improving injectability. These
characteristics were confirmed to arise from the GG’s helix
structure loosened by the dopamine’s bulky nature. Moreover,
dopamine’s hydrophilic characteristics were confirmed to create
a more favorable microenvironment for cell growth by promoting swelling
capability and cell attachment. This improved biocompatibility became
more pronounced when the hydrophilicity of dopamine was combined with
a larger specific surface area stemming from the less porous structure
of the dopamine-grafted hydrogels. This effect was apparent from the
live/dead staining images of the as-prepared hydrogels. Meanwhile,
the nonionic cross-linked DFG (DG) hydrogel showed the lowest protein
expression in the immunofluorescence staining images obtained after
28 days of culture, supporting that it had the highest degradability
and associated cell-releasing ability. That tendency was also observed
in the gene expression data acquired by real-time polymerase chain
reaction (RT-PCR) analysis. RT-PCR analysis also revealed that the
DG hydrogel carrier could upregulate the visual function-related gene
of RPE. Overall, the DG hydrogel system demonstrated its feasibility
as a carrier of RPE cells and its potential as a means of improving
visual function.
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