Influence of dityrosine nanotubes on the expression of dopamine and differentiation in neural cells

In this study, we report the synthesis of self-assembled dityrosine nanotubes as a biologically functional scaffold and their interactions with neural cells. Quantum chemical methods were used to determine the forces involved in the self-assembly process. The physicochemical properties of the nanostructures relevant to their potential as bioactive scaffolds were characterized. The morphology, secondary structure, crystallinity, mechanical properties, and thermal characteristics of YY nanotubes were analyzed. The influence of these nanotubes as scaffolds for neural cells was studied in vitro to understand their effects on cell proliferation, morphology, and gene expression. The scanning electron microscopy and fluorescence confocal microscopy demonstrated the feasibility of nanotube scaffolds for enhanced adhesion to rat and human neural cells (PC12 and SH-SY5Y). Preliminary ELISA and qPCR analyses demonstrate the upregulation of dopamine synthesis and genes involved in dopamine expression and differentiation. The expression levels of DβH, AADC, VMAT2 and MAOA in SH-SY5Y cells cultured on the nanotube scaffolds for 7 days were elevated in comparison to the control cells.

Biomimetic synthesis of chondroitin sulfate-analogue hydrogels for regulating osteogenic and chondrogenic differentiation of bone marrow mesenchymal stem cells

As a typical representative of crucial glycosaminoglycans (GAGs), chondroitin sulfate (CS) with sulfonated polysaccharide in structures extensively exists in the extracellular matrix (ECM) and exhibits peculiar bioactivity on the regulation of cells behaviors and fates (e.g. proliferation and differentiation) in organisms. Nevertheless, some intrinsic disadvantages of natural CS mainly ascribe to the intricate structure and inhomogeneous composition (especially the uncontrollable sulfonate degrees), resulting in overt restrictions on its physiological functions and applications. Although recent bionic synthesis of artificial GAGs analogues at the molecular level have already provides an efficient strategy to reconstruct GAG for regulating the cellular behaviors and fates, it still remains great challenges to rationally design and synthesize GAGs analogues with special composition and structure for precisely mimicking ECM. Simultaneously, the relevant regulation process of GAG analogues on cell fate needs to be further studied as well. Herein, chondroitin sulfate-analogue (CS-analogue) hydrogels with diverse contents of saccharide and sulfonate units in the networks were fabricated through photo-polymerization and then characterized by Fourier transform infrared (FT-IR) spectroscopy, zeta potential and scanning electron microscope (SEM). Additionally, CS-analogue hydrogels with proper mechanical properties exhibited favorable swelling, degradation performance and prominent cytocompatibility. According to cell cultivation results, CS-analogue hydrogel with a certain proportion of saccharide and sulfonate units presented preferable promotion on the adhesion, spreading, proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs), shedding light on the significance of saccharide and sulfonate units in regulating cell behaviors. Furthermore, BMSCs cultivated with CS-analogue hydrogels under different culture conditions were also systematically investigated, revealing that with the help of cultivation environment CS-analogue hydrogels owned the remarkable capacity of directing either chondrogenic or osteogenic differentiation of BMSCs. Therefore, it is envisioned that versatile CS-analogue hydrogels would have promising application prospects in the biomedical and clinical fields.

Heparin mimics and fibroblast growth factor-2 fabricated nanogold composite in promoting neural differentiation of mouse embryonic stem cells

The replacement therapy or transplantation using neural cells, which differentiated from stem cells, has emerged as a promising strategy for repairing damaged neural tissues and helping functional recovery in the treatment of neural system diseases. The challenge, however, is how to control embryonic stem cell fate so that neural differentiation can be efficiently directed to enrich a neuron cell population, and meanwhile to maintain their bioactivities. This is a key question and has a very significant impact in regenerative medicine. Here we proposed a new neural-differentiation inductive nanocomposite, containing gold nanoparticles (AuNPs), poly(2-methacrylamido glucopyranose-co-3-sulfopropyl acrylate) (PMS), and basic fibroblast growth factor (FGF2), for the high efficient directional neural-specific differentiation of mouse embryonic stem cells (mESCs). In this AuNP-PMS/FGF2 composite, PMS, playing as the high-active mimic of heparin/heparan sulfate (HS), is covalently anchored to AuNPs and bound with FGF2 on the surface of nanoparticles, forming a HS/FGF2 complex nanomimics to facilitate its binding to FGF receptor (FGFR) and promote high neural-inductive activity of mESCs. The stability, bioactivity and biocompatibility of the composite are investigated in this study. The results showed that the AuNP-PMS/FGF2 composite could maintain a long-term stability at room temperature for at least 8 days, and greatly promote the neural differentiation of mESCs. Compared with the other materials, the AuNP-PMS/FGF2 composite could significantly stimulate the expression of the specific neural differentiation markers (nestin and β3-tubulin), while obviously down-regulate the mRNA production of pluripotency marker Oct-4 in mESCs. Moreover, the promotion effect of the composite on neuronal maturation marker β3-tubulin expression achieved maximally at the low concentration of FGF2 (4 ng/mL), which suggested the high efficiency of AuNP-PMS/FGF2 composite in neural differentiation of mESCs. Meanwhile, both mESCs and L929 cells showed desirable growth during the incubation with AuNP-PMS/FGF2 composite. The AuNP-PMS/FGF2 system presents a new way to achieve HS/FGF2 complex nanomimics efficiently for the neural differentiation of mESCs.

Dual Pathway for Promotion of Stem Cell Neural Differentiation Mediated by Gold Nanocomposites

The neural differentiation of embryonic stem cells (ESCs) is of great value in the treatment of neurodegenerative diseases. On the basis of the two related signaling pathways that direct the neural differentiation of ESCs, we used gold nanoparticles (GNP) as a means of combining chemical and physical cues to trigger the neurogenic differentiation of stem cells. Neural differentiation-related functional units (glyco and sulfonate units on glycosaminoglycans, GAG) were anchored on the GNP surface and were then transferred to the cell membrane surface via GNP-membrane interactions. The functional units were able to activate the GAG-related signaling pathway, in turn promoting differentiation and maturation of stem cells into neuronal lineages. In addition, using the photothermal effect of GNP, the differentiation-inducing factor retinoic acid (RA), could be actively delivered into cells via laser irradiation. The RA-related intracellular signaling pathway was thereby further triggered, resulting in strong promotion of neurogenesis with a 300-fold increase in mature neural marker expression. The gold nanocomposites developed in this work provide the basis for a new strategy directing ESCs differentiation into nerve cells with high efficiency and high purity by acting on two related signaling pathways.

The effect of human platelet lysate on the differentiation ability of human adipose-derived stem cells cultured on ECM-coated surfaces

Human mesenchymal stem cells (hMSCs), such as human adipose-derived stem cells (hADSCs), present heterogeneous characteristics, including varying differentiation abilities and genotypes. hADSCs isolated under different conditions exhibit differences in stemness. We isolated hADSCs from human fat tissues via culture on different cell culture biomaterials including tissue culture polystyrene (TCPS) dishes and extracellular matrix protein (ECM)-coated dishes in medium supplemented with 5% or 10% serum-converted human platelet lysate (hPL) or 10% fetal bovine serum (FBS) as a control. Currently, it is not clear whether xeno-free hPL in the cell culture medium promotes the ability of hMSCs such as hADSCs to differentiate into several cell lineages compared to the xenomaterial FBS. We investigated whether a synchronized effect of ECM (Matrigel, fibronectin, and recombinant vitronectin) coatings on TCPS dishes for efficient hADSC differentiation could be observed when hADSCs were cultured in hPL medium. We found that Matrigel-coated dishes promoted hADSC differentiation into osteoblasts and suppressed differentiation into chondrocytes in 10% hPL medium. Recombinant vitronectin- and fibronectin-coated dishes greatly promoted hADSC differentiation into osteoblasts and chondrocytes in 5% and 10% hPL media. hPL promoted hADSC differentiation into osteoblasts and chondrocytes compared to FBS on the fibronectin-coated surface and recombinant vitronectin-coated surface.

Amphipathic β-cyclodextrin nanocarriers serve as intelligent delivery platform for anticancer drug

A novel glutathione-responsive (GSH-responsive) star-like amphiphilic polymer (C₁₂H₂₅)₁₄-β-CD-(S-S-mPEG)₇ (denoted as CCSP) was designed for efficient antitumor drug delivery. The amphiphilic β-cyclodextrin (β-CD) self-polymerize in water to form a sphere with a diameter of 40-50 nm. The secondary hydroxyl groups of β-CD were modified by dodecyl to form a hydrophobic core and the primary hydroxyl groups of β-CD were decorated with PEG through disulfide bond to form a hydrophilic shell. Since the hydrophobic cavity of β-CD was maintained, the hydrophobic core formed by dodecyl as well as cavity of β-CD provided CCSP with a loading content as high as 39.6 wt%. Importantly, DOX@CCSP exhibited low drug leakage and negligible cytotoxicity in non-reductive physiological environment, while it showed rapid release and high cytotoxicity in reductive tumorous environment via the breakage of disulfide bond. In view of the above-mentioned advantages of DOX@CCSP nanocarriers such as high loading content, proper size, favorable stimulus-response release performance and low leakage, it is believed that CCSP may offer great potential to be used as an intelligent nanocarrier for anticancer drug delivery.

Xeno-free and feeder-free culture and differentiation of human embryonic stem cells on recombinant vitronectin-grafted hydrogels

Xeno-free culture and cardiomyocyte differentiation of human embryonic stem cells on vitronectin-grafted hydrogels by adjusting surface charge and elasticity.

Improved neural differentiation of stem cells mediated by magnetic nanoparticle-based biophysical stimulation

Stem cell therapy shows great potential in the treatment of neurodegenerative diseases, in which efficient neural differentiation of stem cells is still challenging.

Fabrication of Supramolecular Bioactive Surfaces via β-Cyclodextrin-Based Host-Guest Interactions

Supramolecular host-guest interactions provide a facile and versatile basis for the construction of sophisticated structures and functional assemblies through specific molecular recognition of host and guest molecules to form inclusion complexes. In recent years, these interactions have been exploited as a means of attaching bioactive molecules and polymers to solid substrates for the fabrication of bioactive surfaces. Using a common host molecule, β-cyclodextrin (β-CD), and various guest molecules as molecular building blocks, we fabricated several types of bioactive surfaces with multifunctionality and/or function switchability via host-guest interactions. Other groups have also taken this approach, and several intelligent designs have been developed. The results of these investigations indicate that, compared to the more common covalent bonding-based methods for attachment of bioactive ligands, host-guest based methods are simple, more broadly ("universally") applicable, and allow convenient renewal of bioactivity. In this Spotlight on Applications, we review and summarize recent developments in the fabrication of supramolecular bioactive surfaces via β-CD-based host-guest interactions. The main focus is on the work from our laboratory, but highlights on work from other groups are included. Applications of the materials are also emphasized. These surfaces can be categorized into three types based on: (i) self-assembled monolayers, (ii) polymer brushes, and (iii) multilayered films. The host-guest strategy can be extended from material surfaces to living cell surfaces, and work along these lines is also reviewed. Finally, a brief perspective on the developments of supramolecular bioactive surfaces in the future is presented.