An injectable hydrogel formed by in situ cross-linking of glycol chitosan and multi-benzaldehyde functionalized PEG analogues for cartilage tissue engineering

Abstract

In this study, a muti-benzaldehyde functionalized poly(ethylene glycol) analogue, poly(ethylene oxide-co-glycidol)-CHO (poly(EO-co-Gly)-CHO), was designed and synthesized for the first time, and applied as a cross-linker to develop an injectable hydrogel system. Simply mixing two aqueous precursor solutions of glycol chitosan (GC) and poly(EO-co-Gly)-CHO led to the in situ formation of chemically cross-linked hydrogels under physiological conditions. The cross-linking was attributed to a Schiff's base reaction between amino groups of GC and aldehyde groups of poly(EO-co-Gly)-CHO. The gelation time, water uptake, mechanical properties and network morphology of the GC/poly(EO-co-Gly) hydrogels were well modulated by varying the concentration of poly(EO-co-Gly)-CHO. Degradation of the in situ formed hydrogels was confirmed both in vitro and in vivo. The integrity of the GC/poly(EO-co-Gly) hydrogels was maintained for up to 12 weeks subcutaneously in ICR mice. The feasibility of encapsulating chondrocytes in the GC/poly(EO-co-Gly) hydrogels was assessed. Live/Dead staining assay demonstrated that the chondrocytes were highly viable in the hydrogels, and no dedifferentiation of chondrocytes was observed after 2 weeks of in vitro culture. Cell counting kit-8 assay gave evidence of the remarkably sustained proliferation of the encapsulated chondrocytes. Maintenance of the chondrocyte phenotype was also confirmed with an examination of characteristic gene expression. These features suggest that GC/poly(EO-co-Gly) hydrogels hold potential as an artificial extracellular matrix for cartilage tissue engineering.

Effects of cell–cell contact and oxygen tension on chondrogenic differentiation of stem cells

“…Cell aggregation occurs during both in vivo and in vitro chondrogenesis as well as embryonic condensation in three dimensions. Some differences between 2D and 3D results have been indicated [55,62] and 3D environment is more beneficial for chondrogenesis than 2D environment. One of the reasons might come from more cellecell contacts in 3D.…”

“…The stiffness interpretation might also partially account for that three dimensional (3D) culture of cells surrounded by a hydrogel is beneficial for chondrogenesis more than 2D culture [55].…”

Preparation, characterization, and biocompatibility evaluation of poly(Nɛ-acryloyl-l-lysine)/hyaluronic acid interpenetrating network hydrogels

“…Live/dead staining method is a popular method to 360 evaluate the cell viability and proliferation in vitro reported in the literature (Cao et al, 2015). In this 361 study, the viability and proliferation of MC3T3-E1 cells on the pLysAAm20/HA hydrogels were 362 investigated to confirm the feasibility of the pLysAAm/HA hydrogel to support cell proliferation and 363 differentiation.…”

Injectable and Self-Healing Chitosan Hydrogel Based on Imine Bonds: Design and Therapeutic Applications

“…For instance, Cao et al used multi-aldehyde functionalized PEG as a cross-linker to react with chitosan derivative to form the injectable hydrogel, as presented in Figure 2a [35]. First, the random copolymer poly(EO- co -EPEE) was synthesized by anionic polymerization.…”