ABSTRACT
BACKGROUND: Nowadays, production of nanocomposite scaffolds based on natural biopolymer, bioceramic, and metal ions is a growing field of research due to the potential for bone tissue engineering applications. METHODS: In this study, a nanocomposite scaffold for bone tissue engineering was successfully prepared using collagen (COL), beta-tricalcium phosphate (β-TCP) and strontium oxide (SrO). A composition of β-TCP (4.9 g) was prepared by doping with SrO (0.05 g). Biocompatible porous nanocomposite scaffolds were prepared by freeze-drying in different formulations [COL, COL/β-TCP (1:2 w/w), and COL/β-TCP-Sr (1:2 w/w)] to be used as a provisional matrix or scaffold for bone tissue engineering. The nanoparticles were characterized by X-ray diffraction, Fourier transforms infrared spectroscopy and energy dispersive spectroscopy. Moreover, the prepared scaffolds were characterized by physicochemical properties, such as porosity, swelling ratio, biodegradation, mechanical properties, and biomineralization. RESULTS: All the scaffolds had a microporous structure with high porosity (~ 95–99%) and appropriate pore size (100–200 µm). COL/β-TCP-Sr scaffolds had the compressive modulus (213.44 ± 0.47 kPa) higher than that of COL/β-TCP (33.14 ± 1.77 kPa). In vitro cytocompatibility, cell attachment and alkaline phosphatase (ALP) activity studies performed using rat bone marrow mesenchymal stem cells. Addition of β-TCP-Sr to collagen scaffolds increased ALP activity by 1.33–1.79 and 2.92–4.57 folds after 7 and 14 days of culture, respectively. CONCLUSION: In summary, it was found that the incorporation of Sr into the collagen-β-TCP scaffolds has a great potential for bone tissue engineering applications.
Subject(s)
Animals , Rats , Alkaline Phosphatase , Biopolymers , Bone and Bones , Bone Marrow , Collagen , Fourier Analysis , Freeze Drying , In Vitro Techniques , Ions , Mesenchymal Stem Cells , Nanocomposites , Nanoparticles , Porosity , Spectrum Analysis , Strontium , X-Ray DiffractionABSTRACT
Background: Monolayer electrospun scaffolds have already been used in bone tissue engineering due to their high surface-tovolume ratio, interconnectivity, similarity to natural bone extracellular matrix [ECM], and simple production
Objectives: The aim of this study was to evaluate the dynamic culture effect on osteogenic differentiation and mineralizationi into a compact cellular multilayer nHA-PCL electrospun construct. The dynamic culture was compared with static culture
Materials and Methods: The calcium content, alkaline phosphatase [ALP] activity and cell viability were investigated on days 3 and 7
Results: When the dynamic culture compared to static culture, the mineralization and ALP activity were increased in dynamic culture. After 7 days, calcium contents were 41.24 and 20.44 micro g.[cm[3]][-1], and also normalized ALP activity were 0.32 and 0.19 U.mg[-1] in dynamic and static culture, respectively. Despite decreasing the cell viability until day 7, the scanning electron microscopy [SEM] results showed that, due to higher mineralization, a larger area of the construct was covered with calcium deposition in dynamic culture
Conclusions: The dynamic flow could improve ALP activity and mineralization into the compact cellular multilayer construct cultured in the perfusion bioreactor after 7 days. Fluid flow of media helped to facilitate the nutrients transportation into the construct and created uniform cellular construct with high mineralization. This construct can be applied for bone tissue engineering
ABSTRACT
Objective: In the present study we investigated the effect of a dynamic culture in a shake flask bioreactor [SFB] on the proliferation and differentiation to osteoblasts for human mesenchymal stem cells [hMSCs] cultured on multilayered electrospun PCL-nHA scaffolds
Methods: First, we prepared PCL-nHA scaffolds by electrospinning. After culturing the hMSCs on the scaffolds in a static state, the seeded scaffolds were divided into two groups [static and SFB culture] and incubated up to 21 days. We assessed biocompatibility and cell differentiation by the MTT, calcium, and alkaline phosphatase [ALP] assays on days 7, 14, and 21
Results: The MTT assay evaluated hMSCs proliferation rate on the scaffold layers. There was greater cell proliferation [optical density values] on the layers in the bioreactor [OD=2.18] compared to the static state condition [OD=1.68] on day 21. In order to study osteogenic differentiation, we determined the amount of calcium deposition and ALP activity. We observed a 1.6-fold greater level of calcium deposition for the dynamic culture compared to the static culture, which showed increased cell differentiation within the bioreactor on day 21. The ALP results showed that during 14 days, ALP activity within the bioreactor was 1.55-fold higher than the static culture
Conclusion: The SFB culture displayed a higher proliferation and differentiation of stem cells on PCL-nHA multilayered scaffolds compared to the static state condition
ABSTRACT
Objective: More similarity to in vivo may help to increase the proliferation and differentiation of cells at in vitro culture. The present study has investigated the effect of a dynamic culture medium and nano hydroxyapatite [nHA] presence on proliferation and differentiation of mesenchymal stem cells [MSCs] to bone cells using electrospun polycaprolactone [PCL] scaffolds
Methods: We prepared PCL and PCL-nHA scaffolds by electrospinning. After static culturing of the scaffolds with MSCs, the scaffolds, were divided into two groups of static and dynamic cultures. The dynamic culture scaffolds were placed on a shaker. Cell proliferation and differentiation at days 3, 7 and 14 were investigated by MTT, and the calcium and alkaline phosphatase assays
Results: The obtained results from the MTT assay on day 14 showed an increase of 1.1 times in cell proliferation in the dynamic culture compared to the static culture. During this period, the calcium content produced by cells in the dynamic culture at day 14 were 1.23 times higher for PCL scaffolds and 1.46 times higher for PCL-nHA scaffolds compared to the static culture. Alkaline phosphatase levels for the dynamic state PCL scaffold were 1.24 times more and for PCL-nHA scaffolds were 1.28 times more compared to the static culture at day 14
Conclusion: The obtained results from dynamic culture, showed higher proliferation and differentiation of stem cells to bone for both PCL and PCL-nHA scaffolds compared to the static culture. The amount of cell proliferation and differentiation in the scaffolds that contained nHA was more than scaffolds that did not have nHA
ABSTRACT
Objective: The host immune response against minor donor blood groups may be considered a significant problem in certain groups of patients that undergo transfusions such as those who require repeat transfusions [thalassemia]. A proposed solution is to coat the surface antigens on red blood cells [RBCs] by covalent binding of methoxy polyethylene glycol [mPEG]. This study aims to determine the storage time of PEGylated cells before injection and its effective time during in vivo conditions
Methods: We used mPEG activated by succinimidyl valerate [SVA] to PEGlayte the cells. The stability of the created coating during in vitro conditions was investigated by three methods: counting the numbers of free cells, flow cytometry and qualitative investigation. The appropriate concentration of mPEG for rabbit RBC PEGylation was determined by electron microscopy. The effective time of PEGylated rabbit RBCs was determined with flow cytometric analysis after the injection. In addition, we investigated the serum biochemical properties at 24 hours after the injection
Results: The appropriate concentration of 15 mg/mL for rabbit RBC PEGylation was determined. At 48 hours after injection, 83% of the cells that were alive in the host circulatory system kept their polymeric coating
Conclusion: We determined that 18 days was an appropriate storage time for PEGylated RBCs under in vitro conditions. The effective time of 14 days was determined for PEGylated RBCs by tracking the cells in vivo. An investigation of the serum biochemical properties of rabbits at 24 hours after the injection showed that the RBC coating significantly inhibited stimulation of the host immune system and cell destruction
ABSTRACT
Host immune system response against blood group antigens is a major problem in blood transfusions, especially for thalassemic patients. Thus, an approach was proposed coating the red blood cell [RBC] surface by polyethylene glycol. This study aimed to obtain the optimal simultaneous camouflage of the major and minor antigens by activated methoxy polyethylene glycol [mPEG] with succinimidyl valerate [SVA] and succinimidyl carbonate [SC], separately. The degree of rbc agglutination by antibodies against the major and minor blood groups was used as a surrogate measurement for quantitative assessment of the effectiveness of the surface coating. Also, the RBC morphology was assessed using scanning electron microscope [SEM]. In addition, to evaluate the host immune system response, the PEGylated RBCs were transferred between two different mouse stains. Statistical analysis of the results demonstrated that the optimal reaction conditions for simultaneous coating of the antigens by mPEG-SVA and mPEG-SC are as mPEG[20] in the polymer mixture, 91.2 and 90.0%, and polymer concentration, 17.21 and 19.80 mg.mL[-1], respectively. However, according to the SEM results, the maximum polymer concentration of 14.5 mg.mL[-1] was suggested as the best condition for mPEG-SVA modified human RBCs. It is concluded that the membrane PEGylation camouflages the blood group antigens. This effect is observed significantly for non-ABO/Rh[D] antigens. Also, it is found that the mPEG-SVA provide better coverage than mPEG-SC. The results of in vivo analysis showed that the immune reactions against PEGylated RBCs were considerably reduced, so that the levels of the relevant biochemical parameters in serum were similar to those of the normal hosts 24 hours after transfusion