Engineering three-dimensional (3D) implantable tissue constructs is a promising strategy for replacing damaged or diseased tissues and organs with functional replacements. However, the efficient vascularization of new 3D organs is a major scientific and technical challenge since large tissue constructs or organs require a constant blood supply to survive in vivo. Current approaches to solving this problem generally fall into the following three major categories: (a) cell-based, (b) angiogenic factor-based, and (c) scaffold-based. In this review, we summarize state-of-the-art technologies that are used to develop complex, stable, and functional vasculature for engineered 3D tissue constructs and organs; additionally, we have suggested directions for future research.
Bioengineering ; Tissue Scaffolds

OBJECTIVE: To review the research progress of design of bone scaffolds with different single cell structures. METHODS: The related literature on the study of bone scaffolds with different single cell structures at home and abroad in recent years was extensively reviewed, and the research progress was summarized. RESULTS: The single cell structure of bone scaffold can be divided into regular cell structure, irregular cell structure, cell structure designed based on topology optimization theory, and cell structure designed based on triply periodic minimal surface. Different single cell structures have different structural morphology and geometric characteristics, and the selection of single cell structure directly determines the mechanical properties and biological properties of bone scaffold. It is very important to choose a reasonable cell structure for bone scaffold to replace the original bone tissue. CONCLUSION Bone scaffolds have been widely studied, but there are many kinds of bone scaffolds at present, and the optimization of single cell structure should be considered comprehensively, which is helpful to develop bone scaffolds with excellent performance and provide effective support for bone tissue.
Bone and Bones ; Tissue Scaffolds

Scaffold-free tissue engineered cell sheet is an emerging technology in biomedical field. It can avoid the adverse effects of scaffold materials, and can be further assembled to form more complex three-dimensional functional tissues. The construction of cell sheet is mainly based on the culture substrate composed of sensitive materials. By changing the stimulation factors such as temperature, enzyme, light, ion, redox, pH and sugar, the adhesion behavior of the substrate to the cells could be changed to make the cells detach naturally, thus generating the cell sheet. Recent years have seen the development of various simple and efficient construction technologies of cell sheet due to the development of a variety of novel sensitive culture substrates. The resulted cell sheets with excellent performance have greatly expanded their applications. This review summarized the construction methods of tissue engineered cell sheet and discussed the challenges and future perspectives in this field.
Temperature ; Tissue Engineering ; Tissue Scaffolds

With the development of tissue engineering, a variety of forms of silk fibroin (SF) scaffolds has been applied to research of constructing variety of organization based on cells, which has become scientific focus in recent years. In this paper we introduced the source and structure of SF and the fabrication method of the scaffold, and also address the SF application progress in several relevant fields of tissue engineering, such as bone, cartilage, skin, blood vessel and nerves. Finally, we discuss the future leading prospect of the SF in order to provide reference for subsequent research.
Fibroins ; Humans ; Tissue Engineering ; Tissue Scaffolds

Cryogels are a type of hydrogel material which are fabricated by cryopolymerization at subzero temperature. Due to their unique macroporous structure, shape memory properties and injectability, cryogels have gained significant interest in the fields of tissue engineering for encouraging the repair and regeneration of injured tissues. In this review, the basic concepts relevant to cryogels are introduced, and then the fabrication principle, the process parameters and the unique properties of cryogel are discussed. Next, the latest advances of cryogels as three-dimensional scaffold for various tissue engineering applications are given. Finally, this review summarizes the current limitations of cryogels, and strategies to further improve their properties for tissue engineering. The purpose of this article is to provide a reference guide for the researchers in related fields.
Cryogels ; Porosity ; Tissue Engineering ; Tissue Scaffolds

To serve as carriers of cells and bioactive molecules, three-dimensional scaffolds play a key role in bone defect repair. The chemical component and microstructure of the scaffold can affect the mechanical properties and seed cells. A variety of fabrication techniques have been used in producing scaffolds, some made random porous structure, some created well-designed structure using rapid prototyping methods, and others prepared bio-derived materials as scaffolds. However, scaffolds may vary in their inner structure, mechanical properties and repairing efficiency as well because of different manufacturing methods. In this review, we overview the main achievements concerning the effects of material and microstructure on the mechanical performance, seed cells and defect repair of bone scaffolds.
Biocompatible Materials ; Bone and Bones ; Porosity ; Tissue Scaffolds

Due to limited availability of autologous blood vessels (blood vessels from the same recipient used for vascular transplantation materials) and inadequate growth ability of non-autologous blood vessels (artificial blood vessel transplantation materials), more and more attention has been paid to tissue engineering blood vessels. In this study, we constructed an ammonium phosphate zwitterion modified acellular vascular scaffold with highly biocompatible bone marrow-derived endothelial progenitor cells as the inner layer of a new vascular transplantation material. The vascular acellular scaffolds were modified by a simple method-co-precipitation method. The platelet adhesion test, hemolysis test, recalcification test and cytotoxicity of acellular vascular scaffolds in vitro were evaluated. Ammonium phosphate zwitterions modified endothelial progenitor cells on the surface of acellular scaffolds with concave and convex structure on the surface of natural vascular lumen can be effectively promoted by improving anticoagulant activity. Modified acellular scaffolds have similar mechanical properties to natural blood vessels and can effectively construct endothelialization in vitro. The results of this study provide a preliminary exploration for the modification of vascular acellular scaffolds to achieve anti-thrombosis and endothelialization in vitro.
Blood Vessel Prosthesis ; Humans ; Phosphates ; Thrombosis ; Tissue Engineering ; Tissue Scaffolds

Cartilage tissue engineering, an effective way to repair cartilage defects, requires an ideal scaffold to promote the regeneration performance of stem cells. Cartilage extracellular matrix (CECM) can imitate the living environment of cartilage cells to the greatest extent. CECM not only exhibits good biocompatibility with chondrocytes and stem cells, which can meet the basic requirements of scaffolds, but also promotes chondrocytes to secrete matrix and induce stem cells to differentiate into chondrocytes; as such, this matrix is a better scaffold and has more advantages than existing ones. The promotion and induction effects could be related to various cartilage-related proteins inside. However, the practical application of this technique is hindered by problems, such as poor mechanical properties and insufficient cell penetration of CECM. Association with other materials can compensate for these inadequacies to a certain degree, and finding a combination mode with optimized performance is the application trend of CECM. This review focuses on research of CECM materials in cartilage tissue engineering.
Cartilage ; cytology ; Chondrocytes ; Extracellular Matrix ; Tissue Engineering ; Tissue Scaffolds

OBJECTIVE: This study aims to prepare oriented scaffolds derived from a cartilage extracellular matrix (CECM) and silk fibroin (SF) and use to investigate their physicochemical property in cartilage tissue engineering. METHODS: Oriented SF-CECM scaffolds were prepared from 6% mixed slurry (CECM：SF=1：1) through modified temperature gradient-guided thermal-induced phase separation, followed by freeze drying. The SF-CECM scaffolds were evaluated by scanning electron microscopy (SEM) and histological staining analyses and determination of porosity, water absorption, and compressive elastic modulus of the materials. RESULTS: The SEM image showed that the SF-CECM scaffolds contained homogeneous reticular porous structures in the cross-section and vertical tubular structures in the longitudinal sections. Histological staining showed that cells were completely removed, and the hybrid scaffolds retained proteogly can and collagen. The composition of the scaffold was similar to that of natural cartilage. The porosity, water absorption rate, and vertical compressive elastic modulus of the scaffolds were 95.733%±1.010%, 94.309%±1.302%, and (65.40±4.09) kPa, respectively. CONCLUSIONS The fabricated SF-CECM scaffolds exhibit satisfactory physicochemical and biomechanical properties and thus could be an ideal scaffold in cartilage tissue engineering.
Cartilage ; Extracellular Matrix ; Fibroins ; Porosity ; Silk ; Tissue Engineering ; Tissue Scaffolds

An ideal biologically derived that tissue engineering material of tendon has biological activities and functions, so that it may lead to a perfect effect in histological reparation and reconstruction. In addition, the tissue engineering material can avoid disease transmission, be provided from variety of sources and be weak in immune responses. Generally, there are two kinds biologically derived material, i. e. natural biomaterials and purified biomaterials. In this review, researches about the effect, capability and relevant preparation methods, enhancing strategies and the development in the future are discussed.
Biocompatible Materials ; Humans ; Tendons ; Tissue Engineering ; methods ; Tissue Scaffolds