ABSTRACT
Hydrogels are known as polymer-based networks with the ability to absorb water and other body fluids. Because of this, the hydrogels are used to preserve drugs, proteins, nutrients or cells. Hydrogels possess great biocompatibility, and properties like soft tissue, and networks full of water, which allows oxygen, nutrients, and metabolites to pass. Therefore, hydrogels are extensively employed as scaffolds in tissue engineering. Specifically, hydrogels made of natural polymers are efficient structures for tissue regeneration, because they mimic natural environment which improves the expression of cellular behavior. Producing natural polymer-based hydrogels from collagen, hyaluronic acid (HA), fibrin, alginate, and chitosan is a significant tactic for tissue engineering because it is useful to recognize the interaction between scaffold with a tissue or cell, their cellular reactions, and potential for tissue regeneration. The present review article is focused on injectable hydrogels scaffolds made of biocompatible natural polymers with particular features, the methods that can be employed to engineer injectable hydrogels and their latest applications in tissue regeneration.
Subject(s)
Tissue Engineering , Alginates , Biocompatible Materials , Chitosan , Hyaluronic Acid , Hydrogels , Polymers , Tissue ScaffoldsABSTRACT
The major challenge of tissue regeneration is to develop three dimensional scaffolds with suitable properties which would mimic the natural extracellular matrix to induce the adhesion, proliferation, and differentiation of cells. Several materials have been used for the preparation of the scaffolds for bone regeneration. In this study, novel ethyl cellulose-grafted-poly (É-caprolactone) (EC-g-PCL)/alginate scaffolds with different contents of nano-hydroxyapatite were prepared by combining electrospinning and freeze-drying methods in order to provide nanofibrous/macroporous structures with good mechanical properties. For this aim, EC-g-PCL nanofibers were obtained with electrospinning, embedded layer-by-layer in alginate solutions containing nano-hydroxyapatite particles, and finally, these constructions were freeze-dried. The scaffolds possess highly porous structures with interconnected pore network. The swelling, porosity, and degradation characteristics of the EC-g-PCL/alginate scaffolds were decreased with the increase in nano-hydroxyapatite contents, whereas increases in the in-vitro biomineralization and mechanical strength were observed as the nano-hydroxyapatite content was increased. The cell response to EC-g-PCL/alginate scaffolds with/or without nano-hydroxyapatite was investigated using human dental pulp stem cells (hDPSCs). hDPSCs displayed a high adhesion, proliferation, and differentiation on nano-hydroxyapatite-incorporated EC-g-PCL/alginate scaffolds compared to pristine EC-g-PCL/alginate scaffold. Overall, these results suggested that the EC-g-PCL/alginate-HA scaffolds might have potential applications in bone tissue engineering.
Subject(s)
Alginates/chemistry , Cellulose/analogs & derivatives , Durapatite/chemistry , Nanofibers/chemistry , Polyesters/chemistry , Tissue Scaffolds/chemistry , Bone Regeneration , Bone Substitutes/chemistry , Bone and Bones/cytology , Cell Adhesion , Cell Differentiation , Cell Proliferation , Cells, Cultured , Cellulose/chemistry , Dental Pulp/cytology , Humans , Nanofibers/ultrastructure , Porosity , Stem Cells/cytology , Tissue EngineeringABSTRACT
BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(É-caprolactone)-poly(ethylene glycol)-poly(É-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica (n-SiO2) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and n-SiO2 incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190-260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with n-SiO2. While the hydrophilicity of n-SiO2 incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to n-SiO2 incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and n-SiO2. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.