Articular cartilage and osteochondral tissue engineering techniques: Recent advances and challenges

In spite of the considerable achievements in the field of regenerative medicine in the past several decades, osteochondral defect regeneration remains a challenging issue among diseases in the musculoskeletal system because of the spatial complexity of osteochondral units in composition, structure and functions. In order to repair the hierarchical tissue involving different layers of articular cartilage, cartilage-bone interface and subchondral bone, traditional clinical treatments including palliative and reparative methods have showed certain improvement in pain relief and defect filling. It is the development of tissue engineering that has provided more promising results in regenerating neo-tissues with comparable compositional, structural and functional characteristics to the native osteochondral tissues. Here in this review, some basic knowledge of the osteochondral units including the anatomical structure and composition, the defect classification and clinical treatments will be first introduced. Then we will highlight the recent progress in osteochondral tissue engineering from perspectives of scaffold design, cell encapsulation and signaling factor incorporation including bioreactor application. Clinical products for osteochondral defect repair will be analyzed and summarized later. Moreover, we will discuss the current obstacles and future directions to regenerate the damaged osteochondral tissues

The Synthesis of Size-Adjustable Superparamagnetism Fe3O4 Hollow Microspheres

Abstract One hundred fifty to 300-nm-sized monodisperse iron oxide (Fe3O4) hollow microspheres were synthesized by the one-pot hydrothermal method. The morphology and crystal structure of the as-prepared hollow microspheres was characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy, while the magnetic property was investigated by vibrating sample magnetometer. We found that the particle size of the hollow microspheres was related to the amount of sodium citrate, polyacrylamide (PAM), and urea. The hollow structure of Fe3O4 microspheres has high magnetization saturation values ranging in 49.10–75.41 emu/g

Emerging advances in fluorescence imaging and phototherapy of arthritis

Abstract Arthritis is a chronic disease whose etiology is difficult to pinpoint, and the difficulty of arthritis detection and subsequent treatment causes enormous distress to patients. In recent years, thanks to advances in medicine and detection, a variety of treatment modalities for arthritis have emerged. The combination of emerging detection technologies with different anti‐inflammatory medications and even advances in surgical techniques have all played a positive role in the treatment of arthritis. In the present work, we have collected relevant literature on fluorescence (FL) imaging and phototherapy of arthritis in recent years, intending to reveal the advantages and potential application value of FL imaging and phototherapy for researchers. Meanwhile, due to the shortcomings of FL imaging and phototherapy in the diagnosis and treatment of arthritis, we advocate overcoming these difficulties in future research

Polyoxyethylene Diamine Modification of Poly(amide-imide)-polyethylene Glycol Exhibits Excellent Hydrophilicity, Degradability, and Biocompatibility

We designed and synthesized the polyoxyethylene diamine (H2N-PEG-NH2) and poly(amide-imide)-polyethylene glycol (PAI-PEG) copolymers. The physical and chemical properties, mechanical properties, and in vitro biocompatibility of the materials were characterized. The results showed that the best elongation at break and recovery were obtained when the amount of PEG was 5 wt%. With the increase in PEG content, the degradation rate, hydrophilic property, tensile strength and tensile modulus of the copolymer decreased to a certain extent. The material had the best thermal stability and mechanical properties when 5 wt% PEG was added. Cytocompatibility evaluation showed that the addition of PEG could enhance the cell compatibility of the material and make it potentially suitable for application in bone repair

A Highly Hydrophilic and Biodegradable Novel Poly(amide-imide) for Biomedical Applications

A novel biodegradable poly(amide-imide) (PAI) with good hydrophilicity was synthesized by incorporation of l-glycine into the polymer chain. For comparison purposes, a pure PAI containing no l-glycine was also synthesized with a three-step method. In this study, we evaluated the novel PAI’s thermal stability, hydrophilicity, solubility, biodegradability and ability to support bone marrow mesenchymal stem cell (BMSC) adhesion and growth by comparing with the pure PAI. The hydrophilic tests demonstrated that the novel PAI has possible hydrophilicity at a 38° water contact angle on the molecule surface and is about two times more hydrophilic than the pure PAI. Due to an extra unit of l-glycine in the novel PAI, the average degradation rate was about 2.4 times greater than that of the pure PAI. The preliminary biocompatibility studies revealed that all the PAIs are cell compatible, but the pure PAI exhibited much lower cell adhesion than the l-glycine-incorporated novel PAI. The hydrophilic surface of the novel PAI was more suitable for cell adhesion, suggesting that the surface hydrophilicity plays an important role in enhancing cell adhesion and growth

Effects of Uptake of Hydroxyapatite Nanoparticles into Hepatoma Cells on Cell Adhesion and Proliferation

Hydroxyapatite nanoparticles (nano-HAPs) were prepared by homogeneous precipitation, and size distribution and morphology of these nanoparticles were determined by laser particle analysis and transmission electron microscopy, respectively. Nano-HAPs were uniformly distributed, with rod-like shapes sizes ranging from 44.6 to 86.8 nm. Attached overnight, suspended, and proliferating Bel-7402 cells were repeatedly incubated with nano-HAPs. Inverted microscopy, transmission electron microscopy, and fluorescence microscopy were used to observe the cell adhesion and growth, the culture medium containing nano-HAPs, the cell ultrastructure, and intracellular Ca2+ labeled with a fluo-3 calcium fluorescent probe. The results showed that nano-HAPs inhibited proliferation of Bel-7402 cells and, caused an obvious increase in the concentration of intracellular Ca2+, along with significant changes in the cell ultrastructure. Moreover, nano-HAPs led suspended cells and proliferating cells after trypsinized that did not attach to the bottom of the culture bottle died. Nano-HAPs continuously entered these cells. Attached, suspended, and proliferating cells endocytosed nano-HAPs, and nanoparticle-filled vesicles were in the cytoplasm. Therefore, hepatoma cellular uptake of nano-HAPs through endocytosis was very active and occurred continuously. Nano-HAPs affected proliferation and adhesion of hepatoma cells probably because uptake of nano-HAPs blocked integrin-mediated cell adhesion, which may have potential significance in inhibiting metastatic cancer cells to their target organ

Synthesis, Characterization of Nano- β

It is difficult to synthesize nano-β-tricalcium phosphate (nano-β-TCP) owing to special crystal habit. The aim of this work was to synthesize nano-β-TCP using ethanol-water system and characterize it by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Malvern laser particle size analyzer, and transmission electron microscope (TEM). In addition, the inhibitory effect of nano-β-TCP on human hepatocellular carcinoma (HepG2) cells was also investigated using MTT assay, lactate dehydrogenase (LDH) leakage test, and 4′-6-diamidino-2-phenylindole (DAPI) staining. The results showed that negatively charged rod-like nano-β-TCP with about 55 nm in diameter and 120 nm in length was synthesized, and the average particle size of nano-β-TCP was 72.7 nm. The cell viability revealed that nano-β-TCP caused reduced cell viability of HepG2 cells in a time- and dose-dependent manner. These findings presented here may provide valuable reference data to guide the design of nano-β-TCP-based anticancer drug carrier and therapeutic systems in the future

Oriented Fibers Cooperate with DFO to Prevent Tendon Adhesions by Improving the Repair Microenvironment

Abstract To solve the problem of tendon adhesion after an operation, an anti‐adhesion membrane is designed, which can inhibit the exogenous healing of tendons and promote endogenous healing. Here, poly[3(S)‐methyl‐morpholine‐2,5‐dione‐co‐lactic acid] P(MMD‐co‐LA) containing alanine units is obtained by melt ring‐opening polymerization (ROP). It can effectively reduce the production of acidic degradation products that cause aseptic inflammation. Then a kind of oriented P(MMD‐co‐LA)/deferoxamine (DFO) anti‐adhesion membrane with good mechanical properties, cell adhesion properties, and induced macrophage polarization properties is constructed by electrospinning. In vitro and in vivo studies have shown that oriented fibrous membranes can down‐regulate the expression of inflammatory cytokines. In addition, the fibrous membrane can up‐regulate the expression of angiogenesis‐related genes, namely HIF1‐α, SDF‐1α, and VEGF, by releasing DFO in situ, thus promoting the revascularization of tendon defects and providing nutritional support for endogenous tendon healing. This method provides a new barrier strategy to reduce tendon adhesion through anti‐inflammation combined with vascularization to inhibit exogenous tendon healing while promoting tendon endogenous healing. The results provide essential insights into the corresponding regulation of the tendon healing microenvironment