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Nanohydroxyapatite-reinforced chitosan composite hydrogel for bone tissue repair in vitro and in vivo.

Dhivya S, Saravanan S, Sastry TP, Selvamurugan N - J Nanobiotechnology (2015)

Bottom Line: The potential application of hydrogels as three-dimensional (3D) matrices in tissue engineering has gained attention in recent years because of the superior sensitivity, injectability, and minimal invasive properties of hydrogels.The presence of nHAp in the Zn-CS/nHAp/β-GP hydrogel enhanced swelling, protein adsorption, and exogenous biomineralization.The hydrogel was found to be non-toxic to mesenchymal stem cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, School of Bioengineering, SRM University, Kattankulathur, 603203, Tamil Nadu, India. dhivi.shankar@gmail.com.

ABSTRACT

Background: Bone loss during trauma, surgeries, and tumor resection often results in critical-sized bone defects that need to be filled with substitutionary materials. Complications associated with conventional grafting techniques have led to the development of bioactive tissue-engineered bone scaffolds. The potential application of hydrogels as three-dimensional (3D) matrices in tissue engineering has gained attention in recent years because of the superior sensitivity, injectability, and minimal invasive properties of hydrogels. Improvements in the bioactivity and mechanical strength of hydrogels can be achieved with the addition of ceramics. Based on the features required for bone regeneration, an injectable thermosensitive hydrogel containing zinc-doped chitosan/nanohydroxyapatite/beta-glycerophosphate (Zn-CS/nHAp/β-GP) was prepared and characterized, and the effect of nHAp on the hydrogel was examined.

Methods: Hydrogels (Zn-CS/β-GP, Zn-CS/nHAp/β-GP) were prepared using the sol-gel method. Characterization was carried out by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) as well as swelling, protein adsorption, and exogenous biomineralization studies. Expression of osteoblast marker genes was determined by real-time reverse transcriptase polymerase chain reaction (RT-PCR) and western blot analyses. In vivo bone formation was studied using a rat bone defect model system.

Results: The hydrogels exhibited sol-gel transition at 37°C. The presence of nHAp in the Zn-CS/nHAp/β-GP hydrogel enhanced swelling, protein adsorption, and exogenous biomineralization. The hydrogel was found to be non-toxic to mesenchymal stem cells. The addition of nHAp to the hydrogel also enhanced osteoblast differentiation under osteogenic conditions in vitro and accelerated bone formation in vivo as seen from the depositions of apatite and collagen.

Conclusions: The synthesized injectable hydrogel (Zn-CS/nHAp/β-GP) showed its potential toward bone formation at molecular and cellular levels in vitro and in vivo. The current findings demonstrate the importance of adding nHAp to the hydrogel, thereby accelerating potential clinical application toward bone regeneration.

No MeSH data available.


Related in: MedlinePlus

SEM images of exogenous biomineralized a Zn-CS/β-GP and b Zn-CS/nHAp/β-GP hydrogels in SBF for 21 days. c and d are magnified images of the above, respectively. EDX spectra of e Zn-CS/β-GP and f Zn-CS/nHAp/β-GP hydrogels. g XRD spectra of the mineralized hydrogels.
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Fig3: SEM images of exogenous biomineralized a Zn-CS/β-GP and b Zn-CS/nHAp/β-GP hydrogels in SBF for 21 days. c and d are magnified images of the above, respectively. EDX spectra of e Zn-CS/β-GP and f Zn-CS/nHAp/β-GP hydrogels. g XRD spectra of the mineralized hydrogels.

Mentions: The in vitro exogenous biomineralization of the hydrogels prepared was examined by immersing them in simulated body fluid (SBF) solutions for 21 days. The presence of apatite crystals on the surface of the hydrogels was examined and confirmed by SEM analyses (Figure 3a–d). Figure 3a and b represent the SEM images of exogenous biomineralized Zn-CS/β-GP and Zn-CS/nHAp/β-GP hydrogels, respectively. Figure 3c and d represent the magnified images of the above. The pattern of apatite formation was intense on the surface of the hydrogels containing nHAp (Figure 3d). This could be due to the availability of negatively charged hydroxyl groups on hydroxyapatite that acted as nucleation sites to initiate crystal deposition. Furthermore, the presence of calcium and phosphate ions in the biomineralized Zn-CS/β-GP (Figure 3e) and Zn-CS/nHAp/β-GP (Figure 3f) hydrogels was confirmed in the energy dispersive spectroscopy (EDX) spectra. The characteristic diffraction peaks of hydroxyapatite at values of 2θ from 31.8° to 52.5°, in accordance to JCPDS-09-0432, were observed in all tested samples (Figure 3g). The observed sharper peaks implied that the degree of crystallinity of the hydrogel samples had increased after biomineralization.Figure 3


Nanohydroxyapatite-reinforced chitosan composite hydrogel for bone tissue repair in vitro and in vivo.

Dhivya S, Saravanan S, Sastry TP, Selvamurugan N - J Nanobiotechnology (2015)

SEM images of exogenous biomineralized a Zn-CS/β-GP and b Zn-CS/nHAp/β-GP hydrogels in SBF for 21 days. c and d are magnified images of the above, respectively. EDX spectra of e Zn-CS/β-GP and f Zn-CS/nHAp/β-GP hydrogels. g XRD spectra of the mineralized hydrogels.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4464993&req=5

Fig3: SEM images of exogenous biomineralized a Zn-CS/β-GP and b Zn-CS/nHAp/β-GP hydrogels in SBF for 21 days. c and d are magnified images of the above, respectively. EDX spectra of e Zn-CS/β-GP and f Zn-CS/nHAp/β-GP hydrogels. g XRD spectra of the mineralized hydrogels.
Mentions: The in vitro exogenous biomineralization of the hydrogels prepared was examined by immersing them in simulated body fluid (SBF) solutions for 21 days. The presence of apatite crystals on the surface of the hydrogels was examined and confirmed by SEM analyses (Figure 3a–d). Figure 3a and b represent the SEM images of exogenous biomineralized Zn-CS/β-GP and Zn-CS/nHAp/β-GP hydrogels, respectively. Figure 3c and d represent the magnified images of the above. The pattern of apatite formation was intense on the surface of the hydrogels containing nHAp (Figure 3d). This could be due to the availability of negatively charged hydroxyl groups on hydroxyapatite that acted as nucleation sites to initiate crystal deposition. Furthermore, the presence of calcium and phosphate ions in the biomineralized Zn-CS/β-GP (Figure 3e) and Zn-CS/nHAp/β-GP (Figure 3f) hydrogels was confirmed in the energy dispersive spectroscopy (EDX) spectra. The characteristic diffraction peaks of hydroxyapatite at values of 2θ from 31.8° to 52.5°, in accordance to JCPDS-09-0432, were observed in all tested samples (Figure 3g). The observed sharper peaks implied that the degree of crystallinity of the hydrogel samples had increased after biomineralization.Figure 3

Bottom Line: The potential application of hydrogels as three-dimensional (3D) matrices in tissue engineering has gained attention in recent years because of the superior sensitivity, injectability, and minimal invasive properties of hydrogels.The presence of nHAp in the Zn-CS/nHAp/β-GP hydrogel enhanced swelling, protein adsorption, and exogenous biomineralization.The hydrogel was found to be non-toxic to mesenchymal stem cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, School of Bioengineering, SRM University, Kattankulathur, 603203, Tamil Nadu, India. dhivi.shankar@gmail.com.

ABSTRACT

Background: Bone loss during trauma, surgeries, and tumor resection often results in critical-sized bone defects that need to be filled with substitutionary materials. Complications associated with conventional grafting techniques have led to the development of bioactive tissue-engineered bone scaffolds. The potential application of hydrogels as three-dimensional (3D) matrices in tissue engineering has gained attention in recent years because of the superior sensitivity, injectability, and minimal invasive properties of hydrogels. Improvements in the bioactivity and mechanical strength of hydrogels can be achieved with the addition of ceramics. Based on the features required for bone regeneration, an injectable thermosensitive hydrogel containing zinc-doped chitosan/nanohydroxyapatite/beta-glycerophosphate (Zn-CS/nHAp/β-GP) was prepared and characterized, and the effect of nHAp on the hydrogel was examined.

Methods: Hydrogels (Zn-CS/β-GP, Zn-CS/nHAp/β-GP) were prepared using the sol-gel method. Characterization was carried out by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) as well as swelling, protein adsorption, and exogenous biomineralization studies. Expression of osteoblast marker genes was determined by real-time reverse transcriptase polymerase chain reaction (RT-PCR) and western blot analyses. In vivo bone formation was studied using a rat bone defect model system.

Results: The hydrogels exhibited sol-gel transition at 37°C. The presence of nHAp in the Zn-CS/nHAp/β-GP hydrogel enhanced swelling, protein adsorption, and exogenous biomineralization. The hydrogel was found to be non-toxic to mesenchymal stem cells. The addition of nHAp to the hydrogel also enhanced osteoblast differentiation under osteogenic conditions in vitro and accelerated bone formation in vivo as seen from the depositions of apatite and collagen.

Conclusions: The synthesized injectable hydrogel (Zn-CS/nHAp/β-GP) showed its potential toward bone formation at molecular and cellular levels in vitro and in vivo. The current findings demonstrate the importance of adding nHAp to the hydrogel, thereby accelerating potential clinical application toward bone regeneration.

No MeSH data available.


Related in: MedlinePlus