Conductive hydrogels are attracting considerable interest in view of their potential in a wide range of applications that include healthcare and electronics. Such hydrogels are generally incorporated with conductive materials/polymers....
Repair
of critical size bone defects is a clinical challenge that
usually necessitates the use of bone substitutes. For successful bone
repair, the substitute should possess osteoconductive, osteoinductive,
and vascularization potential, with the ability to control post-implantation
infection serving as an additional advantage. With an aim to develop
one such substitute, we optimized a zinc-doped hydroxyapatite (HapZ) nanocomposite decorated on reduced graphene oxide (rGO),
termed as G3HapZ, and demonstrated its potential
to augment the bone repair. The biocompatible composite displayed
its osteoconductive potential in biomineralization studies, and its
osteoinductive property was confirmed by its ability to induce mesenchymal
stem cell (MSC) differentiation to osteogenic lineage assessed by
in vitro mineralization (Alizarin red staining) and expression of
osteogenic markers including runt-related transcription factor 2 (RUNX-2),
alkaline phosphatase (ALP), type 1 collagen (COL1), bone morphogenic
protein-2 (BMP-2), osteocalcin (OCN), and osteopontin (OPN). While
the potential of G3HapZ to support vascularization
was displayed by its ability to induce endothelial cell migration,
attachment, and proliferation, its antimicrobial activity was confirmed
using S. aureus. Biocompatibility of
G3HapZ was demonstrated by its ability to induce bone regeneration
and neovascularization in vivo. These results suggest
that G3HapZ nanocomposites can be exploited
for a range of strategies in developing orthopedic bone grafts to
accelerate bone regeneration.
The aim of stem cell therapy is to repair damaged tissues. Some of the challenges facing its success include cell retention and survival at the wound site. While the retention of cells has been addressed by employing scaffolds, the survival of transplanted cells in the repair tissue is however low. It is hypothesized that the observed regeneration is more a result of migration of tissue repairing cells from adjoining tissues in response to paracrine factors secreted by implanted cells than by the implanted cells per se. In this study, we report the synthesis of a self-healing hybrid hydrogel that is injectable. The hybrid hydrogel was developed using the dynamic equilibrium of Schiff base linkage between the aldehyde groups on carboxymethyl cellulose dialdehyde (CMC-D) and amino groups on carboxymethyl chitosan (CMCh). The hydrogel stiffness and kinetics of gelation were observed to be modulated with different molecular weights of chitosan. In vitro studies demonstrated the cytocompatibility, hemocompatibility, and biodegradability of the hydrogel. The chemotactic, proliferative, and wound-healing response of cells to the paracrine factors secreted from the mesenchymal stem cell (MSC)−hydrogel composite confirmed the ability of the hydrogel to support the paracrine response of stem cells. Our results suggest that the synthesized hydrogel−MSC composite could serve as a potential scaffold for studying the in vitro response of cells to the paracrine factors released by the encapsulated cells as well as a cell delivery vehicle for in vivo applications.
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