Nano-hydroxyapatite has been widely used as reconstructive and prosthetic material for osseous tissue,owing to its excellent biocompatibility and tissue bioactivity.But the poor mechanical property of hydroxyapatite restricts its further application.In order to enhance the comprehensive performance of the material,many researches have been dedicated to the synthesization of the composite materials.This article reviews the main preparation methods of nano-hydroxyapatite and the advancement in research of its composite.The directions in this research area are described as well.

Tissue engineering composites for bone defect treatment is currently a hot spot of the research field.Mechanical loading on tissue engineering composites is important to bone formation and related research has attracted more and more attention.In the field of tissue engineering research,the establishment of a standardized animal model is the basis of experimental research for exploring the effects of different mechanical loading on in situ repair of bone defect and its action mechanism.This paper reviews the approaches used to establish experimental model of bone defect under mechanical loading such as animal selection,defect preparation,fixation and loading mode in order to provide a reference for related research.

The technology of water-jet is an advanced technology of cold cutting which is widely used in industry, espe-cially in the cutting of metal, glass, ceramics and paper. Its character and classification are introduced, especially basic prineiple, development and application. The technology of water-jet will paly an important role in medicine.

Objective To obtain the experimental data of vascular tissue engineering.MethodsThe vascular endothelial cells (VEC) and vascular smooth muscle cells (VSMCs) were acquired and cultured, and then seeded on vascular tissue engineering materials. The porous gelatin-chitosan scaffold with VSMCs was subcutaneously implanted, followed by the observation of the cell growth ten days later.ResultsThe two kinds of cells were successfully cultured and their morpholoical and immunohistochemical characteristics were consistent with vascular endothelial and VSMCs respectively. The VSMCs could grow extensively on the scaffold after the in vivo implantation. The scaffold were wrapped by the fibrous tissue ten days later after the in vitro implantation of VSMCs. The seed cells grew in the scaffold, and the vessel cavity seen in the center of the scaffold, was quite different from the normal vessel structure.ConclusionIt is feasible to implant the VSMCs with fibrin gels into the living body. The vessels reconstructed, though different from the normal structure, is similar to the embryo of the vessels.

ObjectiveTo investigate the feasibility of construction of engineered blood vessel using chitosan tube and fibrin gel as scaffold.MethodsVascular endothelial cells and smooth muscle cells were harvested from aortas of a rat, respectively. After expansion in vitro, vascular endothelial cells were seeded onto the inner surface of chitosan tube and smooth muscle cells mixed with fibrin gel seeded onto outer surface of the scaffold to construct engineered blood vessels. Inverted microscope, immunohistochemical staining and scanning electronic microscope were used to evaluate the construct.ResultsVascular endothelial cells formed monolayer and covered the inner surface of chitosan tube. Smooth muscle cells survived in the fibrin gel and grew in a 3-dimensional manner. ConclusionChitosan-fibrin gel may be potentially used as scaffold of engineered blood vessels.

Objective:To explore the clinical and genetic etiology of a Chinese pedigree affected with type 2 Long QT syndrome (LQTS).Methods:A pedigree with type 2 LQTS presented at Fuwai Central China Cardiovascular Hospital on August 23, 2019 was selected as the study subject. Peripheral blood samples were collected from the proband and her parents. Following extraction of genomic DNA, whole exome sequencing (WES) was carried out for the proband, and candidate variant was screened through functional annotation and protein-protein interaction (PPI) analysis. Sanger sequencing was conducted to verify the pathogenicity of candidate variant. This study was approved by Medical Ethics Committee of the Fuwai Central China Cardiovascular Hospital (Ethics No. 2019-15).Results:WES revealed that the proband has harbored a missense variant of the KCNH2 gene, namely c. 1478A>G (p.Tyr493Cys), which was confirmed by Sanger sequencing to have inherited from her father. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic (PM2_supporting+ PM5+ PP3+ PP4). Conclusion:The KCNH2 gene c. 1478A>G (p.Tyr493Cys) variant probably underlay the type 2 LQTS in this pedigree.

Prosthetic loosening and periprosthetic inflammation, as serious complications after joint replacement surgery, often require the secondary surgery for repair, which is easy to adversely affect the physical/mental health and economic status of patients.Studies have shown that the functional phenotype expressed by macrophages by different stimuli, namely macrophage polarization state, prolonged M1 polarization can lead to the continuation of long-term inflammation, while timely and effective M2 macrophage phenotype will lead to enhanced osteogenesis and tissue remodeling cytokine secretion and subsequent osseointegration, which play a crucial role in the development and outcome of prosthetic loosening and periprosthetic inflammation.The local micro-environment of extracellular matrix (ECM) is an important factor in the activation, migration, proliferation and fusion of macrophages. Researchers have deeply understood it mainly through the crosstalk between surface properties of biomaterials and macrophages. As an effector cell, macro-phages can perform complex spatiotemporal cellular functional responses by sensing the physical and chemical environment (surface topography, wettability, chemical composition, biological proteins) represented by surface properties of biomaterials.This paper summarizes the recent findings on macrophage polarization and material surface properties.

With the development of the 3rd-generation high-throughput sequencing technology and tissue engineering, recent studies show that many long-chain non-coding RNAs (LncRNAs) have played an important role in osteogenic differentiation of mesenchymal stem cells (MSCs). LncRNAs, which are involved in the regulation of mechanical regulation, further regulate bone-related cell functions and play a regulatory role at multiple levels, including transcription, post-transcriptional and epigenetic. LncRNAs may be involved in the osteogenic differentiation and bone remodeling of MSCs, the regulation of bone-related cell functions as a mechanical response molecule, as well as the pathological process of skeletal diseases.

Objective To construct a two-dimensional (2D) composite membrane and a three-dimensional (3D) biomimetic scaffold by silk fibroin (SF), type I collagen (Col-I) and hydroxyapatite (HA) blends in vitro, so as to study its physicochemical properties, as well as biocompatibility and explore the feasibility of its application in tissue engineering scaffold materials. Methods 2D composite membranes and 3D scaffolds were prepared by blending SF/Col-I/HA at the bottom of cell culture chamber and low temperature 3D printing combined with vacuum freeze drying. The biocompatibility was evaluated by mechanical property testing, scanning electron microscope and Micro-CT to examine the physicochemical properties of the material, and cell proliferation was detected to evaluate its biocompatibility. Results Stable 2D composite membrane and 3D porous structural scaffolds were obtained by blending and low temperature 3D printing. The mechanical properties were consistent. The pore size, water absorption, porosity and elastic modulus were all in accordance with the requirements of constructing tissue engineering bone. The scaffold was a grid-like white cube with good internal pore connectivity; HA was evenly distributed in the composite membrane, and the cells were attached to the composite membrane in a flat shape; the cells were distributed around pore walls of the scaffold. The shape of the shuttle was fusiform, and the growth and proliferation were good. Conclusions The composite membrane and 3D scaffold prepared by SF/Col-I/HA blending system had better pore connectivity and pore structure, which was beneficial to cell and tissue growth and nutrient transport. Its physicochemical properties and biocompatibility could meet the requirements of bone tissue engineering biomaterials.