Bone Marrow Derived Mesenchymal Stem Cells Adhesion Research Articles

E7-Conjugated Bio-Inspired Microspheres as a Biological Barrier for Guided Tissue Regeneration.

Guided tissue regeneration (GTR), which is based on creating a physical barrier to prevent the downgrowth of epithelial and connective tissues into the defect site, has been widely used in clinical practice for periodontal regeneration for many years. However, its outcomes remain variable due to highly specific indications, the demand for proficient surgical skills, and frequent occurrence of complications. In this study, we developed a new GTR biomaterial that acts as a biological barrier for epithelial cells and fibroblasts while also serving as a scaffold for bone marrow-derived mesenchymal stem cells (BMSCs) and periodontal ligament stem cells (PDLSCs). This innovative GTR biomaterial is bioinspired injectable microspheres that are self-assembled from nanofibers, and their surfaces are conjugated with E7, a short peptide that selectively promotes BMSC and PDLSC adhesion but inhibits the attachment and spreading of epithelial cells and gingival fibroblasts. The selective affinity afforded by E7 on the surfaces of the nanofibrous microspheres facilitated the colonization of BMSCs in the periodontal defect, thereby substantially improving functional periodontal regeneration, as evidenced by enhanced new bone formation, reduced root exposure, and diminished attachment loss. The remarkable superiority of the bioinspired microspheres over conventional GTR materials in promoting periodontal regeneration underscores the potential of this innovative approach to enhance the efficacy of functional periodontal tissue regeneration.

Regulation of localized corrosion of 316L stainless steel on osteogenic differentiation of bone morrow derived mesenchymal stem cells

Localized corrosion has become a concerning issue in orthopedic implants as it is associated with peri-implant adverse tissue reactions and implant failure. Here, the pitting corrosion of 316 L stainless steels (316 L SSs) was initiated by electrochemical polarization to simulate the in vivo localized corrosion of orthopedic implants. The effect of localized corrosion on osteogenic differentiation of bone marrow derived mesenchymal stem cells (BMSCs) was systematically studied. The results suggest that pitting corrosion of 316 L SS reduced the viability, adhesion, proliferation, and osteogenic differentiation abilities of BMSCs, especially for the cells around the corrosion pits. The relatively high concentrations of metallic ions such as Cr3+ and Ni2+ released by pitting corrosion could cause cytotoxicity to the BMSCs. The inhomogeneous electrochemical environment resulted from localized corrosion could promote reactive oxygen species (ROS) generation around the corrosion pits and cause oxidative stress of BMSCs. In addition, localized corrosion could also electrochemically interact with the cells and lead to cell membrane depolarization. The depolarized cell membranes and relatively high levels of ROS mediated the degradation of the osteogenic capacity of BMSCs. This work provides new insights into corrosion-mediated cell function degeneration as well as the material-cell interactions.

In vitro evaluation of degradation, cytocompatibility and antibacterial property of polycaprolactone/hydroxyapatite composite coating on bioresorbable magnesium alloy

Polycaprolactone/hydroxyapatite (PCL/HA) composite coating was fabricated by a combination of hydrothermal and dipping methods to delay the degradation of Mg alloy AZ31 as bioresorbable materials. The PCL/HA coating was composed of nano rod-shape HA crystals and PCL filled in the space of HA crystals. Compared with the single HA coating, the binding strength between the PCL/HA composite coating and Mg alloy was obviously improved and the PCL/HA coating still adhered to the surface of AZ31 substrate even after 38 days of immersion. The electrochemical corrosion rate of HA coated sample was reduced by ten times after being filled by PCL. The electrochemical impedance spectroscopy (EIS) and immersion test results showed that the PCL/HA composite coating could provide a more effective barrier for Mg substrate than the HA coating alone. The cytocompatibility and the antibacterial property of HA coating and PCL/HA coating were evaluated by culturing with bone marrow-derived mesenchymal stem cells (BMSCs) and methicillin-resistant staphylococcus aureus (MRSA) for 24 h under direct culture conditions, respectively. The PCL/HA composite coating showed better BMSC cell compatibility, more suitable for BMSC adhesion than HA coating alone and showed a potential application prospect as a biological materials. However, from the perspective of clinical applications, the antibacterial property of PCL/HA composite coating needs to be further improved.

Pitting behavior of 316L stainless steel in direct culture with mesenchymal stem cells

Corrosion is one of the dominating reasons for failure of metallic implants. The corrosion behavior of the 316 L stainless steels (316 L SS) in direct culture with bone marrow derived mesenchymal stem cells (BMSCs) was studied via electrochemical measurements. The adhesion, proliferation and apoptosis of BMSCs could be detected by electrochemical impedance spectroscopy (EIS). The presence of BMSCs could decline the stability of the passive films and lower the pitting potential of the 316 L SS. The pitting corrosion preferentially initiated at the peripheries of the BMSCs, which was driven by surface overpotential potential generated from the negative transmembrane potential.

Angiogenic Hyaluronic Acid Hydrogels with Curcumin-Coated Magnetic Nanoparticles for Tissue Repair.

Angiogenic magnetic hydrogels are attractive for tissue engineering applications because their integrated properties can improve angiogenesis while providing magnetic guidance and stimulation for tissue healing. In this study, we synthesized magnetic nanoparticles (MNPs) with curcumin as an angiogenic agent, referred to as CMNPs, via a one-pot coprecipitation method. We dispersed CMNPs in hyaluronic acid (HyA) to create angiogenic magnetic hydrogels. CMNPs showed a slightly reduced average diameter compared to that of MNPs and a curcumin content of 11.91%. CMNPs exhibited a sustained slow release of curcumin when immersed in a revised simulated body fluid (rSBF). Both CMNPs and MNPs showed a dose-dependent cytocompatibility when cultured with bone marrow-derived mesenchymal stem cells (BMSCs) using the direct exposure culture method in vitro. The average BMSC density increased when the concentrations of CMNPs or MNPs increased from 100 to 500 μg/mL, but the cell density decreased when the nanoparticle concentration reached 1000 μg/mL. CMNPs showed a weaker magnetic response than MNPs both in air and in water immediately after synthesis but retained the magnetism better than MNPs when embedded in the HyA hydrogel because of less oxidation. CMNPs were able to respond to magnetic guidance even when the porcine skin or muscle tissues were placed in between the nanoparticles and external magnet. The magnetic hydrogels of HyA_CMNP and HyA_MNP promoted the adhesion of BMSCs in a direct exposure culture. The HyA_CMNP group also showed the highest secretion of the vascular endothelial growth factor with the release of curcumin in vitro. Overall, our magnetic hydrogels integrated the desirable properties of cytocompatibility and angiogenesis with magnetic guidance, thus proving to be promising for improving tissue regeneration.

Superhydrophobic fluoride conversion coating on bioresorbable magnesium alloy – fabrication, characterization, degradation and cytocompatibility with BMSCs

A micro-nano structure CaF2 chemical conversion layer was prepared on fluoride-treated AZ31 alloy, then the composite fluoride conversion film (CaF2/MgF2) was modified by stearic acid (SA) and fabricated a superhydrophobic surface. The fluoride-treated magnesium, fluoride conversion film and superhydrophobic coating were characterized by SEM, EDS, XRD and FTIR. The properties of coatings’ adhesion and corrosion resistance were evaluated via tape test and electrochemical measurement. The cytocompatibility of the MgF2, CaF2 and super-hydrophobic CaF2/SA surface was investigated with bone marrow-derived mesenchymal stem cells (BMSCs) by direct culture for 24 h. The results showed that the superhydrophobic fluoride conversion coating composed of inner MgF2 layer and the outer CaF2/SA composite layer had an average water contact angle of 152°. SA infiltrated into the micro-nano structure CaF2 layer and formed a strong adhesion with CaF2 layer. Furthermore, the super-hydrophobic coating showed higher barrier properties and corrosion resistance compared with the fluoride conversion film and fluoride-treated AZ31 alloy. The BMSC adhesion test results demonstrated MgF2 CaF2 and CaF2/SA coatings were all nontoxic to BMSC. At the condition of in direct contact with cells, MgF2 showed higher cell density and enhanced the BMSCs proliferation, while CaF2 and CaF2/SA coating showed no statistically difference in cell density compared with glass reference but the CaF2 and CaF2/SA coating were not conducive to BMSCs adhesion.

Hydrothermally grown TiO2-nanorods on surface mechanical attrition treated Ti: Improved corrosion fatigue and osteogenesis

Current bioactive modifications of Ti-based materials for promoting osteogenesis often decrease corrosion fatigue strength (σcf) of the resultant implants, thereby shortening their service lifespan. To solve this issue and accelerate the osteogenesis process, in the present study, a TiO2 nanorods (TNR)-arrayed coating was hydrothermally grown on optimal surface mechanical attrition treated (SMATed) titanium (S-Ti). The microstructure, bond integrity, residual stress distribution, and corrosion fatigue of TNR-coated S-Ti (TNR/S-Ti) and the response of macrophages and bone marrow-derived mesenchymal stem cells (BMSCs) to TNR/S-Ti were investigated and compared with those of mechanically polished Ti (P-Ti), S-Ti, and TNR-coated P-Ti (TNR/P-Ti). S-Ti showed a nanograined layer and an underlying grain-deformed region with residual compressive stress, which was sustained even when it was hydrothermally coated with TNR. TNR on S-Ti showed nanotopography, composition, and bond strength almost identical to those of P-Ti. While TNR/P-Ti showed a considerable decrease in σcf compared to P-Ti, TNR/S-Ti exhibited an improved σcf which was even higher than that of P-Ti. Biologically, TNR/S-Ti enhanced adhesion, differentiation, and mineralization of BMSCs, and it also promoted adhesion and M1-to-M2 transition of macrophages as compared to S-Ti and P-Ti. With rapid phenotype switch of macrophages, the level of proinflammatory cytokines decreased, while anti-inflammatory cytokines were upregulated. In co-culture conditions, the migration, differentiation, and mineralization of BMSCs were enhanced by increased level of secretion factors of macrophages on TNR/S-Ti. The modified structure accelerated bone apposition in rabbit femur and is expected to induce a favorable immune microenvironment to facilitate osseointegration earlier; it can also simultaneously improve corrosion fatigue resistance of Ti-based implants and thereby enhance their service life.

In vitro study on electrospun lecithin-based poly (L-lactic acid) scaffolds and their biocompatibility

Lecithin is a natural mixture of phospholipids and neutral lipids, and plays a vital role in the maintenance of cell-membrane integrity for all of the basic biological processes.This study aimed to evaluate the adhesion and growth of bone marrow-derived mesenchymal stem cells (BMSCs) on the three-dimensional (3D) electrospun lecithin-containing poly (L-lactic acid) (PLLA) fibrous scaffolds. In this study, PLLA and 0-15% of lecithin (wt.%) were dissolved in methylene chloride and thoroughly mixed to fabricate fibrous scaffolds by electrospinning technique. Surface morphology and hydrophilic properties of the scaffolds were characterized by scanning electron microscopy (SEM) and water uptake, respectively. The cytocompatibility of electrospun scaffolds and their potential cytotoxic effects on cells were studied over 8 days by seeding rat BMSCs on the scaffolds of PLLA containing 0-15% lecithin. Then cell proliferation was tested by CCK-8 assay and cell injury was assessed by measuring the release of intracellular lactate dehydrogenase (LDH). And cell morphology was studied by Toluidine blue staining, propidium iodide staining and SEM. The hydrophilicity was dramatically increased with an increase of lecithin content in the modified PLLA/lecithin scaffolds, as determined by rate of water uptake. In addition, the results obtained from in vitro assays suggested that the electrospun PLLA/5%lecithin scaffolds could possess the optimal hydrophilicity, higher adhesion and proliferation of BMSCs than PLLA, and they also did not lead to any significant toxic effects to cells. Moreover, BMSCs on PLLA/5%lecithin scaffolds tended to maintain their phenotypic shape and integrate with the microfibers to form a 3D cellular network, indicating a favorable interaction between this electrospun lecithin-based scaffolds and cells. The study demonstrated that the electrospun PLLA/lecithin fibrous scaffolds showed much better hydrophilicity and biocompatibility by introducing lecithin into the polymer in comparison with pure PLLA, which would offer a promising strategy for constructing tissue engnineered blood vessel.

Adsorption of serum proteins on titania nanotubes and its role on regulating adhesion and migration of mesenchymal stem cells.

Migration and differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) is an important biological process in tissue regeneration. Nanostructured titanium materials are believed to play a fundamental role in dental and orthopedic applications. However, the protein adsorption on nanostructured titanium materials and its correlation with the subsequent cell behaviors have not been studied. In this work, the titania nanotube arrays with different tubular diameters ranging from 27.3 to 88.2 nm were fabricated by using an electrochemical etching method. The adsorbed amounts and types of cell adhesion-related proteins (such as fibronectin, vitronectin, and laminin) from serum were investigated, revealing that these proteins were preferred to bind onto the surface with nanotubes of a smaller diameter. Adhesion and migration of BMSCs were studied as a function of different nanotube diameters in the presence or absence of serum proteins. Compared with the nanotube surface with a larger tubular diameter (88.2 nm), the surface with a smaller one could better support BMSCs in terms of adhesion and spreading. The pre-adsorbed serum proteins significantly enhanced adhesion and migration abilities of BMSCs. However, the adequate interactions between cells and serum proteins on the nanotubes surface with smallest nanotubes in diameter weakened cell mobility. Arrangement of cytoskeleton and expressions of key genes and proteins were studied, revealing that the nanostructured surfaces and pre-adsorbed proteins jointly mediated the adhesion and migration of BMSCs.

Age-Related Regeneration of Osteochondral and Tibial Defects by a Fibrin-Based Construct in vivo.

Tissue–biomaterial interactions in different microenvironments influence significantly the repair and regeneration outcomes when a scaffold or construct is implanted. In order to elucidate this issue, a fibrin gel filled macroporous fibrin scaffold (fibrin-based scaffold) was fabricated by loading fibrinogen via a negative pressure method, following with thrombin crosslinking. The macroporous fibrin scaffold exhibited a porous structure with porosity of (88.1 ± 1.3)%, and achieved a modulus of 19.8 ± 0.4 kPa at a wet state after fibrin gel filling, providing a suitable microenvironment for bone marrow-derived mesenchymal stem cells (BMSCs). The in vitro cellular culture revealed that the fibrin-based scaffold could support the adhesion, spreading, and proliferation of BMSCs in appropriate cell encapsulation concentrations. The fibrin-based scaffolds were then combined with BMSCs and lipofectamine/plasmid deoxyribonucleic acid (DNA) encoding mouse-transforming growth factor β1 (pDNA-TGF-β1) complexes to obtain the fibrin-based constructs, which were implanted into osteochondral and tibial defects at young adult rabbits (3 months old) and aged adult rabbits (12 months old) to evaluate their respective repair effects. Partial repair of osteochondral defects and perfect restoration of tibial defects were realized at 18 weeks post-surgery for the young adult rabbits, whereas only partial repair of subchondral bone and tibial bone defects were found at the same time for the aged adult rabbits, confirming the adaptability of the fibrin-based constructs to the different tissue microenvironments by tissue-biomaterial interplays.

Improved Corrosion Fatigue and Immunomodulatory Osteogenesis of Hydrothermally Grown TiO <sub> 2</sub> Nanorods Coated SMATed-Titanium

Current active modifications of Ti-based materials for promoting osteogenesis often decrease corrosion fatigue strength (Lcf ) of the resultant implants, shortening their service lifespan. To solve the complication and accelerate osteogenesis, herein, a TiO2 nanorods (TNR)-arrayed coating was hydrothermally grown on optimally surface mechanical attrition treated (SMATed) titanium (S-Ti). The microstructure, bond integrity, residual stress distribution and corrosion fatigue of TNR coated S-Ti (TNR/S-Ti) as well as the response of macrophages and bone marrow-derived mesenchymal stem cells (BMSCs) to TNR/S-Ti were investigated, together with mechanically polished Ti (P-Ti), S-Ti and TNR coated P-Ti (TNR/P-Ti). Consequently, S-Ti displayed a nanograined layer and an underlying grains-deformed region both with residual compressive stress, which could be sustained even hydrothermally coated with TNR. TNR on S-Ti presented a nanotopography, composition and bond strength almost identical to that on P-Ti. While TNR/P-Ti displayed a considerable decrease in Lcf compared to P-Ti, TNR/S-Ti revealed an improved Lcf even higher than P-Ti. Biologically, TNR/S-Ti enhanced adhesion, differentiation and mineralization of BMSCs, but also promoted adhesion and M1-to-M2 transition of macrophages than S-Ti and P-Ti. With rapid phenotype switch of macrophages, pro-inflammatory cytokines decreased while anti-inflammatory cytokines upregulated. Under co-culture conditions, migration, differentiation and mineralization of BMSCs were enhanced by the increased secretion factors of macrophages on TNR/S-Ti. Such novel modification structure accelerated bone apposition in rabbit femur, and could be expected to elicit a favorable immune microenvironment to facilitate osseointegration earlier, but also simultaneously improve the corrosion fatigue resistance and thereby service-life of Ti-based implants.

Degradation behaviors and cytocompatibility of Mg/β-tricalcium phosphate composites produced by spark plasma sintering.

Magnesium (Mg)-based materials have shown great potentials for bioresorbable implant applications. Previous studies showed that Mg with 10 and 20 vol % β-tricalcium phosphate (β-TCP) composites produced by spark plasma sintering, improved mechanical properties when compared with pure Mg. The objectives of this study were to evaluate the degradation behaviors of Mg/10% β-TCP and Mg/20% β-TCP composites in revised stimulated body fluid (rSBF), and to determine their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs) using the direct culture method. During the 11 days of immersion in rSBF, Mg/β-TCP composites showed different degradation behaviors at different immersion periods, that is, the initial stage (0-1 hr), the mid-term stage (1 hr to 2 days), and the long-term stage (2-11 days). The counter effects of mass loss due to microgalvanic corrosion and mass gain due to deposition of Ca-P containing layers resulted in slower Mg2+ ion release for Mg/20% β-TCP than Mg/10% β-TCP in the mid-term, but eventually 16% mass loss for Mg/20% β-TCP and 10% mass loss for Mg/10% β-TCP after 11 days of immersion. The in vitro studies with BMSCs showed the highest cell adhesion density (i.e., 68% of seeding density) on the plate surrounding the Mg/10% β-TCP sample, that is, under the indirect contact condition of direct culture. The β-TCP showed a positive effect on direct adhesion of BMSCs on the surface of Mg/β-TCP composites. This study elucidated the degradation behaviors and the cytocompatibility of Mg/β-TCP composites in vitro; and, further studies on Mg/ceramic composites are needed to determine their potential for clinical applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2238-2253, 2019.

Nano-to-Submicron Hydroxyapatite Coatings for Magnesium-based Bioresorbable Implants \u2013 Deposition, Characterization, Degradation, Mechanical Properties, and Cytocompatibility

Magnesium (Mg) and its alloys have shown attractive biocompatibility and mechanical strength for medical applications, but low corrosion resistance of Mg in physiological environment limits its broad clinical translation. Hydroxyapatite (HA) nanoparticles (nHA) are promising coating materials for decreasing degradation rates and prolonging mechanical strength of Mg-based implants while enhancing bone healing due to their osteoconductivity and osteoinductivity. Conformal HA coatings with nano-to-submicron structures, namely nHA and mHA coatings, were deposited successfully on Mg plates and rods using a transonic particle acceleration (TPA) process under two different conditions, characterized, and investigated for their effects on Mg degradation in vitro. The nHA and mHA coatings enhanced corrosion resistance of Mg and retained 86–90% of ultimate compressive strength after in vitro immersion in rSBF for 6 weeks, much greater than non-coated Mg that only retained 66% of strength. Mg-based rods with or without coatings showed slower degradation than the respective Mg-based plates in rSBF after 6 weeks, likely because of the greater surface-to-volume ratio of Mg plates than Mg rods. This indicates that Mg-based plate and screw devices may undergo different degradation even when they have the same coatings and are implanted at the same or similar anatomical locations. Therefore, in addition to locations of implantation, the geometry, dimension, surface area, volume, and mass of Mg-based implants and devices should be carefully considered in their design and processing to ensure that they not only provide adequate structural and mechanical stability for bone fixation, but also support the functions of bone cells, as clinically required for craniomaxillofacial (CMF) and orthopedic implants. When the nHA and mHA coated Mg and non-coated Mg plates were cultured with bone marrow derived mesenchymal stem cells (BMSCs) using the in vitro direct culture method, greater cell adhesion densities were observed under indirect contact conditions than that under direct contact conditions for the nHA and mHA coated Mg. In comparison with non-coated Mg, the nHA and mHA coated Mg reduced BMSC adhesion densities directly on the surface, but increased the average BMSC adhesion densities under indirect contact. Further long-term studies in vitro and in vivo are necessary to elucidate the effects of nHA and mHA coatings on cell functions and tissue healing.

A thermosensitive RGD-modified hydroxybutyl chitosan hydrogel as a 3D scaffold for BMSCs culture on keloid treatment

Cell therapy with bone marrow-derived mesenchymal stem cells (BMSCs) is a potential method for many disease treatments, including keloid. In the present study, an Arg-Gly-Asp (RGD) modified hydroxybutyl chitosan (HBC) hydrogel (HBC-RGD) was developed to enhance the adhesion and proliferation of BMSCs within the hydrogel. The successful synthesis of HBC-RGD was confirmed by FTIR and 1H NMR. Both HBC and HBC-RGD hydrogel had desired thermosensitivity, biocompatibility and enzymatic degradability in vitro. Compared with HBC hydrogel, HBC-RGD hydrogel was more beneficial for the adhesion and proliferation of BMSCs. Furthermore, the BMSCs incorporated HBC-RGD (BMSCs/HBC-RGD) hydrogel could inhibit the proliferation of keloid fibroblasts (Kfs) and suppress the nodular collagenous fibers of keloid tissue. These results suggested that the HBC-RGD hydrogel could be applied as a potential 3D hydrogel scaffold for cell culture, and BMSCs/HBC-RGD hydrogel was potential to be applied for keloid therapy with subcutaneous in-situ injection in the future.

Enhanced adhesion and proliferation of bone marrow mesenchymal stem cells on β‑tricalcium phosphate modified by an affinity peptide.

Mesenchymal stem cells (MSCs) are often used in orthopedic tissue engineering, and bone marrow-derived mesenchymal stem cells (BMSCs) are currently considered the gold standard. One of the most important issues in MSC-based tissue engineering therapy is the low number of MSCs in pathological tissues. Achieving efficient recruitment of MSCs to defective or damaged tissues in vivo has been a difficult hurdle. The aim of the present study was to construct a biomaterial that can effectively recruit BMSCs to facilitate the repair of pathological tissues. So functional β-tricalcium phosphate (β-TCP) was synthesized using the BMSC affinity peptide DPIYALSWSGMA (DPI) adsorbed onto β-TCP through an adsorption/freeze-drying strategy. C57BL/6 mouse-derived BMSCs were seeded onto the DPI peptide-modified β-TCP (β-TCP-DPI); in vitro experiments demonstrated that β-TCP-DPI enhanced BMSC adhesion and proliferation compared with unmodified β-TCP. Results from the present study indicated that functional β-TCP may be used as an ideal scaffold in tissue engineering and in regenerative medicine.

ERK1/2 and Akt phosphorylation were essential for MGF E peptide regulating cell morphology and mobility but not proangiogenic capacity of BMSCs under severe hypoxia.

Sever hypoxia impairs bone defect repair with bone marrow-derived mesenchymal stem cells (BMSCs). This study proved that mechano-growth factor E (MGF E) peptide could improve the severe hypoxia-induced cell contraction and decline of cell adhesion and migration of BMSCs. Besides, MGF E peptide weakened the effects of severe hypoxia on the cytoskeleton arrangement- and mobility-relevant protein expression levels in BMSCs. The underlying molecular mechanism was also verified. Finally, it was confirmed that MGF E peptide showed an adverse effect on the expression level of vascular endothelial growth factor α in BMSCs under severe hypoxia but could make up for this deficiency through accelerating cell proliferation.

In vitro evaluation of a bone morphogenetic protein‑2 nanometer hydroxyapatite collagen scaffold for bone regeneration.

Scaffold fabrication and biocompatibility are crucial for successful bone tissue engineering. Nanometer hydroxyapatite (nHAP) combined with collagen (COL) is frequently utilized as a suitable osseous scaffold material. Furthermore, growth factors, including bone morphogenetic protein-2 (BMP-2), are used to enhance the scaffold properties. The present study used blending and freeze-drying methods to develop a BMP-2-nHAP-COL scaffold. An ELISA was performed to determine the BMP-2 release rate from the scaffold. Flow cytometry was used to identify rat bone marrow-derived mesenchymal stem cells (BMSCs) prior to their combination with the scaffold. Scanning electron microscopy was used to observe the scaffold structure and BMSC morphology following seeding onto the scaffold. BMSCs were also used to assess the biological compatibility of the scaffold in vitro. BMP-2-nHAP-COL and nHAP-COL scaffolds were assessed alongside the appropriate control groups. Cells were counted to determine early cell adhesion. Cell Counting kit-8 and alkaline phosphatase assays were used to detect cell proliferation and differentiation, respectively. Gross morphology confirmed that the BMP-2-nHAP-COL scaffold microstructure conformed to the optimal characteristics of a bone tissue engineering scaffold. Furthermore, the BMP-2-nHAP-COL scaffold exhibited no biological toxicity and was demonstrated to promote BMSC adhesion, proliferation and differentiation. The BMP-2-nHAP-COL scaffold had good biocompatibility in vitro, and may therefore be modified further to construct an optimized scaffold for future bone tissue engineering.

Nano-biphasic calcium phosphate/polyvinyl alcohol composites with enhanced bioactivity for bone repair via low-temperature three-dimensional printing and loading with platelet-rich fibrin.

Background and aimAs a newly emerging three-dimensional (3D) printing technology, low-temperature robocasting can be used to fabricate geometrically complex ceramic scaffolds at low temperatures. Here, we aimed to fabricate 3D printed ceramic scaffolds composed of nano-biphasic calcium phosphate (BCP), polyvinyl alcohol (PVA), and platelet-rich fibrin (PRF) at a low temperature without the addition of toxic chemicals.MethodsCorresponding nonprinted scaffolds were prepared using a freeze-drying method. Compared with the nonprinted scaffolds, the printed scaffolds had specific shapes and well-connected internal structures.ResultsThe incorporation of PRF enabled both the sustained release of bioactive factors from the scaffolds and improved biocompatibility and biological activity toward bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. Additionally, the printed BCP/PVA/PRF scaffolds promoted significantly better BMSC adhesion, proliferation, and osteogenic differentiation in vitro than the printed BCP/PVA scaffolds. In vivo, the printed BCP/PVA/PRF scaffolds induced a greater extent of appropriate bone formation than the printed BCP/PVA scaffolds and nonprinted scaffolds in a critical-size segmental bone defect model in rabbits.ConclusionThese experiments indicate that low-temperature robocasting could potentially be used to fabricate 3D printed BCP/PVA/PRF scaffolds with desired shapes and internal structures and incorporated bioactive factors to enhance the repair of segmental bone defects.

Composite scaffolds loaded with bone mesenchymal stem cells promote the repair of radial bone defects in rabbit model

This study aimed to investigate the efficacy of three-dimensional scaffolds of silk fibroin/chitosan/nano-hydroxyapatite (SF/CS/nHA) and bone marrow derived mesenchymal stem cells (BMSCs) on the repair of long segmental bone defects in rabbits. BMSCs were cultured with SF/CS/nHA in vitro, and cell proliferation, alkaline phosphatase activity and Ca2+ content were examined. A 15mm segmental defect in the radius was generated in 12 New Zealand White rabbits, which were divided randomly into three groups (n=4): experimental group with SF/CS/nHA scaffold of induced BMSCs; control group with SF/CS/nHA scaffold; and blank group without any materials. Postoperatively at 12 weeks, osteogenesis effect and the degradation and absorption of SF/CS/nHA were evaluated by X-ray, hematoxylin eosin staining, and scanning electron microscopy. In vitro, SF/CS/nHA scaffolds exhibited good biocompatibility and no toxicity. SF/CS/nHA promoted adhesion, growth, and calcium nodule formation of BMSCs compared to control (P<0.05). In vivo, we observed gradual new bone formation and bone defect gradually recovered at 12 weeks in experimental and control group, but more new bone was formed in experimental group (P<0.05). In blank group, limited bone formation was observed and bone defect was obvious. In conclusion, SF/CS/nHA scaffolds loaded with BMSCs achieve high efficacy to repair segmental defect in the radius.

Anodization of magnesium for biomedical applications - Processing, characterization, degradation and cytocompatibility.

Magnesium (Mg)-based biomaterials have been specifically designed and actively explored for biodegradable implant applications since the early 2000s. To realize the benefits of Mg-based materials for medical implant applications, it is critical to control the rate of Mg degradation (i.e. corrosion) in the body. We investigated an environmentally friendly anodization process using KOH electrolyte for modifying the surface of Mg-based materials, and the resulted surface, degradation, and biological properties for biomedical applications. This study reported critical considerations that are important for repeatability of anodization process, homogeneity of surface microstructure and composition, and in vitro evaluations of the degradation and biological properties of surface treated Mg samples. The details in preparation of electrodes, anodization setup, annealing, and sample handling before and after surface treatment (e.g. re-embedding) reported in this article are valuable for studying a variety of electrochemical processes for surface treatment of Mg-based metals, because of enhanced reproducibility.