Mouse Bone Mesenchymal Stem Cells Research Articles

Zinc doping induced differences in the surface composition, surface morphology and osteogenesis performance of the calcium phosphate cement hydration products.

In order to investigate the influence of Zn on the hydration reaction of calcium phosphate cement (CPC), the incompletely hydrated CPC tablets were kept soaking in varying zinc-containing tris-(hydroxymethyl)-aminomethane/hydrochloric acid (Zn-Tris-HCl) buffers. It was found that Zn could retard the CPC hydration, the inhibitory effect was in direct proportional to the Zn content in the Zn-Tris-HCl buffer, and overhigh concentration of Zn (≧800 μM) caused the CPC hydration products having different phase composition and surface morphology. Cell culture experimental results revealed the CPC tablets which were soaked in the Zn-Tris-HCl buffer containing relative low Zn content (≦320 μM) favored the mouse bone mesenchymal stem cells (mBMSCs) spreading. When Zn-doped CPC tablets released 10.91 to 27.15 μM of zinc ions into the cell culture medium, it greatly contributed to the improvement of the proliferation ability and the alkaline phosphatase (ALP) activity of the mBMSCs. In the same case, the expression of osteogenesis related genes such as collagen I and runt-related transcription factor 2 was remarkably up-regulated as well. However, the release of high concentration of Zn (128.58 μM) would significantly reduce the ALP activity of the mBMSCs. Therefore, Zn not only facilitates osteogenesis but also affects the CPC hydration behavior, and the CPC with suitable Zn dosage concentration has great potentials to be used for clinical bone repairing.

New BMSC-Laden Gelatin Hydrogel Formed in Situ by Dual-Enzymatic Cross-Linking Accelerates Dermal Wound Healing.

In situ forming hydrogel shows enormous potential as a therapeutic implant or carrier in tissue repair and regeneration. It can perfectly seal or fill the defective tissue, consequently functioning as a cell/drug delivery vehicle. In this contribution, a new gelatin hydrogel with dual-enzymatic cross-linking of horseradish peroxidase (HRP) and galactose oxidase (GalOx) was developed, and the therapeutic effect of this hydrogel encapsulated with bone mesenchymal stem cells (BMSC) in dermal wound healing was investigated. This hydrogel possesses a quick gelation process within 5 min, a high water content, and a uniform three-dimensional (3D) porous network. The 3D cell culture study indicated that gelatin hydrogel matrix of HRP(5U):GalOx(1U) or HRP(2U):GalOx(1U) could provide a friendly 3D microenvironment for supporting the survival, proliferation, and spread of mouse bone mesenchymal stem cells (BMSC) with negligible cytotoxicity. Hematoxylin and eosin staining test suggested that this hydrogel has superior histocompatibility and minimized immune response in vivo. Furthermore, wound-healing studies on a C57 mouse model of excised wound demonstrated that BMSC-laden gelatin hydrogel could significantly accelerate the wound closure as compared to other groups. These data suggest that this dual-enzymatically cross-linked gelatin hydrogel loaded with BMSC has a great potential in wound healing and other tissue-regeneration applications.

Micro-Nano Bioactive Glass Particles Incorporated Porous Scaffold for Promoting Osteogenesis and Angiogenesis in vitro.

Constructing the interconnected porous biomaterials scaffolds with osteogenesis and angiogenesis capacity is extremely important for efficient bone tissue engineering. Herein, we fabricated a bioactive micro-nano composite scaffolds with excellent in vitro osteogenesis and angiogenesis capacity, based on poly (lactic-co-glycolic acid) (PLGA) incorporated with micro-nano bioactive glass (MNBG). The results showed that the addition of MNBG enlarged the pore size, increased the compressive modulus (4 times improvement), enhanced the physiological stability and apatite-forming ability of porous PLGA scaffolds. The in vitro studies indicated that the PLGA-MNBG porous scaffold could enhance the mouse bone mesenchymal stem cells (mBMSCs) attachment, proliferation, and promote the expression of osteogenesis marker (ALP). Additionally, PLGA-MNBG could also support the attachment and proliferation of human umbilical vein endothelial cells (HUVECs), and significantly enhanced the expression of angiogenesis marker (CD31) of HUVECs. The as-prepared bioactive PLGA-MNBG nanocomposites scaffolds with good osteogenesis and angiogenesis probably have a promising application for bone tissue regeneration.

Mechanistic Insights and Rational Design of a Versatile Surface with Cells/Bacteria Recognition Capability via Orientated Fusion Peptides.

Hospital‐acquired infection causes many deaths worldwide and calls for the urgent need for antibacterial biomaterials used in clinic that can selectively kill harmful bacteria. The present study rationally designs fusion peptides capable of undergoing 2D self‐assembly on the poly(methyl methacrylate) surface to form a smart surface, which can maintain a desirable orientation via electrostatic interactions. The in vitro assay shows that the smart surface can recognize bacteria to exert antibacterial activity and is nontoxic toward mouse bone mesenchymal stem cells. Excitingly, the smart surface can distinguish different bacterial strains. This selective feature, from being broad‐spectrum to being highly selective against S. aureus, can be altered by varying the number of amino acids in the recognition sequences. By all‐atom molecular dynamics simulations, it is also found that the recognition sequence in the peptide is critical for the selectivity toward specific bacterial strains, in which a less accessible surface area for the bacteria in the antimicrobial peptide sequence is responsible for such selectivity. Finally, the smart surface can inhibit S. aureus infection in vivo with much more rapid tissue‐healing compared to the control.

Modification of honeycomb bioceramic scaffolds for bone regeneration under the condition of excessive bone resorption.

Gallium (Ga) ions have been clinically approved for treating the diseases caused by the excessive bone resorption through the systemic administration. Nevertheless, little attention has been given to the Ga-containing biomaterials for repairing bone defects under the pathological condition of excessive bone resorption. In the current study, for the first time the Ga-containing phosphate glasses (GPGs) were introduced to modify the honeycomb β-tricalcium phosphate (β-TCP) bioceramic scaffolds, which were prepared by an extrusion method. The results indicated that the scaffolds were characterized by uniform pore structure and channel-like macropores. The addition of GPGs promoted densification of strut of scaffolds by achieving liquid-sintering of β-TCP, thereby tremendously increasing the compressive strength. The ions released from scaffolds pronouncedly inhibited osteoclastogenesis-related gene expressions and multinuclearity of RAW264.7 murine monocyte cells, as well as expressions of early osteogenic makers of mouse bone mesenchymal stem cells (mBMSCs). However, the scaffolds with lower amount of Ga increased cell proliferation and upregulated expression of late osteogenic maker of mBMSCs. This study offers a novel approach to modify the bioceramic scaffolds for bone regeneration under the condition of accelerated bone resorption. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1314-1323, 2019.

BFGF induces proliferation and migration of mouse bone mesenchymal stem cells

BFGF induces proliferation and migration of mouse bone mesenchymal stem cells

Antimicrobial Titanium Surface via Click-Immobilization of Peptide and Its in Vitro/Vivo Activity.

The use of antimicrobial peptides (AMPs)-functionalized titanium implants is an efficient method for preventing bacterial infection. However, the attachment of AMPs to the surface of titanium implants remains a challenge. In this study, a "clickable" titanium surface was developed by using a silane coupling agent with an alkynyl group. The antimicrobial titanium implant was then constructed through the reaction between the "clickable" surface and azido-AMPs (PEG-HHC36:N3-PEG12-KRWWKWWRR) via click chemistry of Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Such an antimicrobial titanium implant, with an AMP density of 897.4 ± 67.3 ng/cm2 (2.5 ± 0.2 molecules per nm2) on the surface, exhibited good and stable antimicrobial activity, inhibited 90.2% of Staphylococcus aureus and 88.1% of Escherichia coli after 2.5 h of incubation, and even inhibited 69.5% of Staphylococcus aureus after 4 days of degradation. The CCK-8 assay indicated that the antimicrobial titanium implant exhibited negligible cytotoxicity to mouse bone mesenchymal stem cells. In vivo assay illustrated that this implant could kill 78.8% of Staphylococcus aureus after 7 days. This method has great potential for the preparation of antimicrobial titanium implants and the prevention of infections in the clinic.

Study on MgxSr3-x(PO4)2 bioceramics as potential bone grafts.

Magnesium (Mg) and strontium (Sr), which are essential nutrient elements in the natural bone, positively affect the osteogenic activity even in wide ranges of ion concentrations. However, it remains unknown whether magnesium-strontium phosphates [MgxSr3-x(PO4)2] are potential bone grafts for accelerating bone regeneration. Herein, a serial of MgxSr3-x(PO4)2, including Mg3(PO4)2, Mg2Sr(PO4)2, Mg1.5Sr1.5(PO4)2, MgSr2(PO4)2 and Sr3(PO4)2, were synthesized using a solid-state reaction approach. The physicochemical properties and cell behaviors of MgxSr3-x(PO4)2 bioceramics were characterized and compared with the common bone graft β-tricalcium phosphate (β-TCP). The results indicated that various MgxSr3-x(PO4)2 bioceramics differed in compressive strength and in vitro degradation rate. All the MgxSr3-x(PO4)2 bioceramics had excellent biocompatibility. In contrast to β-TCP, the MgxSr3-x(PO4)2 enhanced alkaline phosphatase activity of mouse bone mesenchymal stem cells (mBMSCs), and inhibited osteoclastogenesis-related gene expression of RAW264.7 cells, but did not enhance osteogenesis-related gene expression of mBMSCs which were treated with osteogenesis induction supplements. However, Mg3(PO4)2 stimulated osteogenesis-related gene expression of mBMSCs without the treatment of osteogenesis induction supplements. This work contributes to the design of bone graft and may open a new avenue for the bone regeneration field.

Facile preparation of biocompatible poly(l-lactic acid)-modified halloysite nanotubes/poly(ε-caprolactone) porous scaffolds by solvent evaporation of Pickering emulsion templates

Biocompatible porous scaffolds with tunable microstructures and drug delivery ability have aroused increasing attention in the application of the biomedical fields, especially in tissue engineering. In this study, we have facilely fabricated the poly(l-lactic acid)-modified halloysite nanotubes (m-HNTs)/poly(e-caprolactone) (PCL) porous scaffolds by direct solvent evaporation of m-HNTs stabilized water in oil Pickering emulsion templates, which contain PCL in the oil phase. The obtained scaffolds have possessed the porous microstructures, which can be easily tailored by varying the preparation conditions of emulsion templates including m-HNTs concentrations and the volume ratios of water to oil. Furthermore, the antibacterial drug enrofloxacin (ENR) has been loaded into the scaffolds, and the in vitro release studies show the potential of m-HNTs/PCL porous scaffolds as drug carriers. And the antimicrobial test results have proved that the ENR-loaded porous scaffolds exhibit obvious and long-term antibacterial activity against Escherichia coli. In addition, mouse bone mesenchymal stem cells (mBMSCs) are cultured on the m-HNTs/PCL porous scaffolds, and the results of cell counting kit-8 assay and confocal laser scanning microscope observation show that the m-HNTs/PCL porous scaffolds are cytocompatible, because mBMSCs can attach, develop and proliferate well on the porous scaffolds. All the results indicate that the m-HNTs/PCL porous scaffolds hold great potential applications in tissue engineering as scaffolds and/or drug carriers.

Fabrication of novel bioactive hydroxyapatite-chitosan-silica hybrid scaffolds: Combined the sol-gel method with 3D plotting technique

Sol-gel derived organic/inorganic hybrids, in which organic and inorganic components form co-networks at the molecular level, have demonstrated great potential for providing improved mechanical properties and biological functions in tissue engineering applications. Here, a novel bioactive hydroxyapatite-chitosan-silica hybrid (HA-CSH) scaffold was successfully fabricated by combining the sol-gel method and 3D plotting technique. Physiochemical characterization confirmed that chitosan was hybridized homogeneously with the inorganic phase on nanoscale. The obtained scaffolds possessed precisely controllable and interconnected porous structures. The nano-sized HA formed in situ and dispersed uniformly in the hybrid network, which reduced the water absorption and increased the mechanical strength of the hybrid scaffold under humidity condition as compared to chitosan-silica hybrid (CSH) scaffold. Compression tests showed that the 3D plotted hybrid scaffolds under wet conditions had compressive strengths of 10–13 MPa and elastic moduli of 21–27 MPa and thus met the mechanical requirements of human trabecular bone. Studies on the mineralization process under simulated body fluid (SBF) conditions confirmed that the introduction of HA obviously increased the biological activity of hybrid scaffolds. In vitro cell results indicated that the HA-CSH scaffold not only supported adhesion and proliferation of mouse bone mesenchymal stem cells (mBMSCs), but also improved the osteoinductivity. The alkaline phosphatase activity and mineral deposition on the HA-CSH scaffold were higher than those on the CSH scaffold. These results suggested that the 3D plotted HA-CSH scaffold may be a promising bioactive material for bone tissues regeneration.

Immobilization of an antimicrobial peptide on silicon surface with stable activity by click chemistry.

Infections associated with biomedical implants and devices pose a serious clinical challenge in hospitals worldwide. Antimicrobial peptides (AMPs) have become a great prospect to inhibit this type of infection due to their broad-spectrum antimicrobial activity and low cytotoxicity. However, it is still a challenge to apply AMPs on the biomaterial surface as the activity of AMPs is sensitive to salt or enzyme. In the present study, we prepared a spacer molecule, poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (polySBMA), on a model silicon surface via surface-initiated atom transfer radical polymerization (SI-ATRP). We then modified the antimicrobial peptide HHC36 (KRWWKWWRR) with l-propargylglycine (PraAMP) to improve its salt-tolerant activity and integrated PraAMP onto the spacer molecule using click chemistry. We employed X-ray photoelectron spectroscopy (XPS), contact angle goniometry, and atomic force microscopy (AFM) to confirm the success of the immobilization process. We also characterized the antimicrobial activity and stability of the surface with an antimicrobial assay. The results reveal that the modified surface exhibits good antimicrobial activity to inhibit 98.26% of E. coli, 83.72% of S. aureus, and 81.59% of P. aeruginosa. Furthermore, as compared to the control group without the polySBMA spacer, the modified surface improved its resistance to enzymolysis. An in vitro CCK-8 assay also illustrated that this surface showed negligible cytotoxicity to mouse bone mesenchymal stem cells.

Novel Reduced Graphene Oxide/Zinc Silicate/Calcium Silicate Electroconductive Biocomposite for Stimulating Osteoporotic Bone Regeneration.

In the absence of external assistance, autogenous healing of bone fracture is difficult due to impaired regeneration ability under osteoporosis pathological conditions. In this study, a reduced graphene oxide/zinc silicate/calcium silicate (RGO/ZS/CS) conductive biocomposite with an optimal surface electroconductivity of 5625 S/m was prepared by a two-step spin-coating method. The presence of lamellar apatite nanocrystals on the surfaces of the biocomposite suggests that it has good in vitro biomineralization ability. The silicon and zinc released from the biocomposite induced a significant increase in the osteogenesis of mouse bone mesenchymal stem cells (mBMSCs). Furthermore, alkaline phosphatase activities were further promoted when 3 μA direct current was applied to stimulate the mBMSCs that were cultured on the RGO/ZS/CS surface. However, electrical stimulation failed to further upregulate the osteogenesis-related gene expression. Moreover, RGO/ZS/CS extracts were found to suppress the receptor activator of nuclear factor-κB ligand-induced osteoclastic differentiation of mouse leukemic monocyte macrophages (RAW264.7 cells). Although the zinc ions in the RGO/ZS/CS extracts showed an inhibitory role in human umbilical vein endothelial cell (HUVEC) proliferation, dilutions of the RGO/ZS/CS extracts (1/16, 1/32, and 1/64) promoted HUVEC proliferation, and their angiogenesis-related gene expression was also upregulated. On the basis of the results of the in vitro angiogenesis model, more interconnected tubes formed when the above dilutions of RGO/ZS/CS extracts were added to ECMatrix. The new RGO/ZS/CS electroconductive biocomposite has potential to be used for stimulating osteoporotic bone regeneration.

Immunomodulatory Effects of Calcium and Strontium Co-Doped Titanium Oxides on Osteogenesis.

The effects of calcium (Ca) or strontium (Sr) on host osteogenesis and immune responses have been investigated separately. In clinical practice, these two elements may both be present around an orthopedic device, but their potential synergistic effects on osteogenesis and the immune response have not been explored to date. In this work, we investigated the immunomodulatory effects of Ca and Sr co-doped titanium oxides on osteogenesis in vitro using the mouse macrophage cell line RAW 264.7 alone and in co-culture with mouse bone mesenchymal stem cells (BMSCs), and in vivo using a mouse air-pouch model. Coatings containing Ca and Sr at different concentration ratios were fabricated on titanium substrates using micro-arc oxidation and electrochemical treatment. The in vitro and in vivo results demonstrated that the Ca and Sr concentration ratio has a marked influence on macrophage polarization. The coating with a Ca/Sr ratio of 2:1 was superior to those with other Ca and/or Sr concentrations in terms of modulating M2 polarization, which enhanced osteogenic differentiation of mouse BMSCs in co-culture. These findings suggest that the osteoimmunomodulatory effect of a titanium-oxide coating can be enhanced by modulating the concentration ratio of its components.

Hydrothermal growth of whitlockite coating on β-tricalcium phosphate surfaces for enhancing bone repair potential

In this study, we developed a simple approach for the controllable growth of whitlockite (WH) on a β-tricalcium phosphate surface and investigated its cell viability via CCK-8, its live-dead staining and its alkaline phosphatase activity. Herein, WH with controllable morphologies was prepared by regulating the hydrothermal reaction conditions. The results of scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy indicated that pure hexagonal plates of WH were prepared successfully. In vitro cell experiments showed that WH possessed excellent biocompatibility and effectively promoted the adhesion and proliferation of mouse bone mesenchymal stem cells. The osteogenesis of the WH was also enhanced. The obtained WH was expected to be utilized for promising applications as implantable block materials for bone repair.

Fabrication of Hierarchical Macroporous Biocompatible Scaffolds by Combining Pickering High Internal Phase Emulsion Templates with Three-Dimensional Printing.

Biocompatible and biodegradable porous scaffolds with adjustable pore structure have aroused increasing interest in bone tissue engineering. Here, we report a facile method to fabricate hierarchical macroporous biocompatible (HmPB) scaffolds by combining Pickering high internal phase emulsion (HIPE) templates with three-dimensional (3D) printing. HmPB scaffolds composed of a polymer matrix of poly(l-lactic acid), PLLA, and poly(ε-caprolactone), PCL, are readily fabricated by solvent evaporation of 3D printed Pickering HIPEs which are stabilized by hydrophobically modified silica nanoparticles (h-SiO2). The pore structure of HmPB scaffolds is easily tailored to be similar to natural extracellular matrix (ECM) by varying the fabrication conditions of the Pickering emulsion or adjusting the printing parameters. In addition, in vivo drug release studies which employ enrofloxacin (ENR) as a model drug indicate the potential of HmPB scaffolds as a drug carrier. Furthermore, in vivo cell culture assays prove that HmPB scaffolds that possess good biocompatibility as mouse bone mesenchymal stem cells (mBMSCs) can adhere and proliferate well on them. All the results suggest that HmPB scaffolds hold great potential in bone tissue engineering applications.

The role of miR-122-5p in negatively regulating T-box brain 1 expression on the differentiation of mouse bone mesenchymal stem cells.

To achieve neuronal differentiation of mouse bone mesenchymal stem cells (bMSCs) into neuron-like cells and explore the role of miR-122-5p that may regulate T-box brain 1 (Tbr1) expression during the induction. BMSCs were cultured and induced with butylated hydroxyanisole, retinoic acid (RA), basic fibroblast growth factor, and nerve growth factor in vitro. The cells were stained for neuron-specific enolase (NSE) and β-III-tubulin by immunocytochemistry/immunofluorescence. MiR-122-5p that may regulate Tbr1 expression was predicted by bioinformatics and identified using a Dual-Luciferase assay. The expressions of miR-122-5p and Tbr1 were determined by real-time PCR and western blot before and after the induction. After infection of miR-122-5p, the expressions of Tbr1, NSE, and tauons were measured. BMSCs showed a short spindle shape with a uniform distribution. After 14 days, the induced cells showed neuronal traits with a pyramidal appearance. TargetScan and miRanda showed that miR-122-5p was well complementary with the target site of the Tbr1 3'-untranslated region. Identified by the Dual-Luciferase assay, we found that miR-122-5p could inhibit Tbr1 expression by binding to its 3'-untranslated region. Furthermore, the expressions of Tbr1 mRNA and protein were decreased by real-time PCR and western blot. Overexpression of miR-122-5p downregulated the expressions of Tbr1, NSE, and tauons. MiR-122-5p may negatively regulate Tbr1 expression to affect the differentiation of bMSCs into neuron-like cells.

One‐Pot Fabrication of Poly(ε‐Caprolactone)‐Incorporated Bovine Serum Albumin/Calcium Alginate/Hydroxyapatite Nanocomposite Scaffolds by High Internal Phase Emulsion Templates

In this work, the authors report an effective one‐pot method to prepare poly(ε‐caprolactone) (PCL)‐incorporated bovine serum albumin (BSA)/calcium alginate/hydroxyapatite (HAp) nanocomposite (NC) scaffolds by templating oil‐in‐water high internal phase emulsion (HIPE), which includes alginate, BSA, and HAp in water phase and PCL in oil phase. The water phase of HIPEs is solidified to form hydrogels containing emulsion droplets via gelation of alginate induced by Ca2+ ions released from HAp. And the prepared hydrogels are freeze‐dried to obtain PCL‐incorporated porous scaffolds. The obtained scaffolds possess interconnected pore structures. Increasing PCL concentration clearly enhances the compressive property and BSA stability, decreases the swelling ratio of scaffolds, which assists in improving the scaffold stability. The anti‐inflammatory drug ibuprofen can be highly efficiently loaded into scaffolds and released in a sustained rate. Furthermore, mouse bone mesenchymal stem cells can successfully proliferate on the scaffolds, proving the biocompatibility of scaffolds. All results show that the PCL‐incorporated NC scaffolds possess promising potentials in tissue engineering application. image

BFGF Promotes Migration and Induces Cancer-Associated Fibroblast Differentiation of Mouse Bone Mesenchymal Stem Cells to Promote Tumor Growth.

Tumors recruit bone mesenchymal stem cells (BMSCs) to localize to tumor sites, which induces their conversion into cancer-associated fibroblasts (CAFs) that facilitate tumor progression. However, this process is poorly understood on the molecular level. In this study, we found that 4T1 breast cancer cells promoted the migration of BMSCs, and bFGF neutralizing antibody inhibited the migration of BMSCs induced by a tumor-conditioned medium. In addition, exogenous bFGF enhanced the migration of BMSCs in a dose-dependent manner in vitro. Furthermore, BMSCs promoted the proliferation of 4T1 tumor cells under BMSC-conditioned medium and in tumor xenograft model. Dramatically, BMSCs expressed CAF markers and produced collagen in the tumor microenvironment, and this transition was blocked by bFGF antibody. In addition, exogenous bFGF induced CAF differentiation of BMSCs. And bFGF increased phosphorylation of Erk1/2 and Smad3 in BMSCs and Erk inhibitor PD98059 was shown to block bFGF-induced Erk and Smad3 phosphorylation, suggesting that Erk/Smad3 signaling pathway involved in BMSC transdifferentiation induced by bFGF. Collectively, our results indicate that bFGF signaling plays indispensable roles in BMSC recruitment and transdifferentiation into CAFs and the consequent protumor effects, and targeting tumor stroma through bFGF inhibition maybe a promising strategy to suppress tumor progression.

Effect of Mineralized Layer Topographies on Stem Cell Behavior in Microsphere Scaffold

Modifying substrates through mineralization is a popular way to improve the osteogenic performance. Screening of the best mineralization characteristics on specific substrates for stem cells is meaningful but not fully studied. In this paper, poly(lactic-co-glycolic acid)/hydroxyapatite (PLGA/HA, PH) microsphere scaffolds with superficial pores were fabricated by a low-temperature fusion method. After the mineralization in the 5× stimulated body fluid (SBF) for 0, 7, 12 and 24 h, four mineralized scaffolds (MPH-0, MPH-7, MPH-12 and MPH-24) with different apatite topographies were obtained. It was found that the surface of MPH-7 was evenly decorated with abundant micro-pores, MPH-12 with dense and plain apatite layer, and MPH-24 with small spherical bumps. The responses of mouse bone mesenchymal stem cells (mBMSCs) to the four scaffolds were further studied. The results showed that MPH-7 and MPH-24 had more obvious effects on mBMSCs attachment, proliferation and differentiation than MPH-0 and MPH-12. This work indicated that to obtain the maximum improvement, the mineralization characteristics had to be carefully chosen. This was noteworthy in the chemical modification of surfaces to form the functionalized scaffolds for bone repair.

Tough and Cell-Compatible Chitosan Physical Hydrogels for Mouse Bone Mesenchymal Stem Cells in Vitro.

Most hydrogels involve synthetic polymers and organic cross-linkers that cannot simultaneously fulfill the mechanical and cell-compatibility requirements of biomedical applications. We prepared a new type of chitosan physical hydrogel with various degrees of deacetylation (DDs) via the heterogeneous deacetylation of nanoporous chitin hydrogels under mild conditions. The DD of the chitosan physical hydrogels ranged from 56 to 99%, and the hydrogels were transparent and mechanically strong because of the extra intra- and intermolecular hydrogen bonding interactions between the amino and hydroxyl groups on the nearby chitosan nanofibrils. The tensile strength and Young's modulus of the chitosan physical hydrogels were 3.6 and 7.9 MPa, respectively, for a DD of 56% and increased to 12.1 and 92.0 MPa for a DD of 99% in a swelling equilibrium state. In vitro studies demonstrated that mouse bone mesenchymal stem cells (mBMSCs) cultured on chitosan physical hydrogels had better adhesion and proliferation than those cultured on chitin hydrogels. In particular, the chitosan physical hydrogels promoted the differentiation of the mBMSCs into epidermal cells in vitro. These materials are promising candidates for applications such as stem cell research, cell therapy, and tissue engineering.