Use of a gelatin hydrogel membrane containing β-tricalcium phosphate for guided bone regeneration enhances rapid bone formation

Evaluation of a hydroxyapatite-crosslinked fish gelatin membranes

Background/purpose

Porcine collagen is widely used in regenerative therapies to generate membranes for bone augmentation. However, porcine or bovine gelatin or collagen is often not appropriate for patients with creed and religious beliefs or for allergic reasons. In this study, we evaluated the potential of fish gelatin to generate membranes.

Materials and methods

Fish gelatin and hydroxyapatite (HAp) were used at three different ratios (2:0, 2:1, 2:1.5, and 2:2) to prepare gelatin-hydroxyapatite (G-HAp) membranes via freeze-drying and heat-crosslinking. The surface morphology and cell attachment of G-HAp membranes were observed using scanning electron microscopy and confocal laser microscopy. G-HAp membrane was placed at the bottom of a well plate, and MC3T3-E1 cells were seeded on it. Cell viability and cytotoxicity were tested after 1 and 3 days of culture. Alkaline phosphatase (ALP) and alizarin red staining was performed at 10 and 21 days, respectively.

Results

Viability of cells on G-HAp membrane with the gelatin:HAp ratio of 2:1.5 was significantly higher than that on membranes with other gelatin:HAp ratios. ALP and alizarin red staining showed that ALP-positive areas and calcium deposition were the highest on G-HAp membrane with the gelatin:HAp ratio of 2:1. These membranes showed negligible cytotoxicity.

Conclusion

Fish-derived G-HAp membranes have the potential to promote osteogenic differentiation of MC3T3-E1 cells with negligible cytotoxicity.

A novel γ-PGA composite gellan membrane containing glycerol for guided bone regeneration

An ideal barrier membrane design should incorporate the function of a delivery vehicle for transporting drugs and osteoinductive factors to where the body is under inflammation. In the present study, a functional hydrogel-based barrier membrane is fabricated using calcium-form poly-γ-glutamic acid (γ-PGA) and glycerol blending into gellan gum. The concentration of the calcium-form poly-γ-glutamic acid (γ-PGA) and the glycerol ratio are studied for improving practicability in easy-handling and expanding the coverage area. Gellan gum-based membranes with uniformly distributed calcium aggregates are not only successfully manufactured but also providing excellent characteristics for protein adsorption, bioactivity, and bone cell maturation. Our composite gellan gum-based membranes were tested including to their morphology, mechanical properties, swelling behavior, protein adsorption, drug diffusion, and lysozyme degradation. The biocompatibility, proliferation, and osteoblastic response of membranes were examined by osteoblast-like (MG63) cells. Our results indicate that adequate physical cross-linking with γ-PGA improves the original mechanical properties and delays degradation. Growing glycerol ratio not only enhances the elongation at break and diffusion rate, but it also changes the tensile strength and the remaining weight. In vitro biocompatibility tests, an adequate ratio of γ-PGA modification significantly enhances the proliferation, the secretion of alkaline phosphatase (ALP) and mineralization. However, worth noting is the glycerol-modified membrane cannot bear a close resemblance with the non-glycerol group in the high level of osteoblastic response. In general, these tunable materials with biocompatibility, biodegradability, and positive osteoblastic responses were poised to be possible candidates for bone defect repair.

Fabrication and characterization of dextran/nanocrystalline β-tricalcium phosphate nanocomposite hydrogel scaffolds

Design of bioactive three-dimensional scaffolds to support bone tissue repair and regeneration become a key area of research in tissue engineering. Herein, porous hybrid hydrogels composed of dextran incorporated with nanocrystalline β-tricalcium phosphate (β-TCP) particles were tailor made as scaffolds for bone tissue engineering. β-TCP was successfully introduced within the dextran networks crosslinked through intermolecular ionic interactions and hydrogen bonding confirmed by FTIR spectroscopy. The effect of β-TCP content on equilibrium water uptake and swelling kinetics of composite hydrogels was investigated. It was found that the homogeneous distribution of β-TCP nanoparticles through the hydrogel matrix contributes to higher porosity and swelling capacity. In depth swelling measurements revealed that while in the early stage of swelling, water diffusion follows the Fick's law, for longer time swelling behavior of hydrogels undergo the second order kinetics. XRD measurements represented the formation of apatite layer on the surface of nanocomposite hydrogels after immersion in the SBF solution, which implies their bioactivity. Cell culture assays confirmed biocompatibility of the developed hybrid hydrogels in vitro. The obtained results converge to offer dextran/β-TCP nanocomposite hydrogels as promising scaffolds for bone regeneration applications.

The Regenerative Applicability of Bioactive Glass and Beta-Tricalcium Phosphate in Bone Tissue Engineering: A Transformation Perspective

The conventional applicability of biomaterials in the field of bone tissue engineering takes into consideration several key parameters to achieve desired results for prospective translational use. Hence, several engineering strategies have been developed to model in the regenerative parameters of different forms of biomaterials, including bioactive glass and β-tricalcium phosphate. This review examines the different ways these two materials are transformed and assembled with other regenerative factors to improve their application for bone tissue engineering. We discuss the role of the engineering strategy used and the regenerative responses and mechanisms associated with them.