Research and progress of cartilage tissue-engineering scaffold materials

Due to the limited self healing capacity of human cartilage,the repair of defects gives rise to a challenging clinical problem.Cartilage tissue engineering provides a new method to solve cartilage repair.However,the search for a suitable biological vector material has long been the focus of research interest in this regard.In this paper,the present situation of cartilage tissue engineering vector materials is reviewed.

The development of tissue engineering corneal scaffold:which one the history will choose?

Since the 21st century,the development of corneal tissue engineering technology has been developing rapidly.With the progress of biomaterials,cell culture and tissue engineering technology,tissue engineering cornea has gained great development in both basic scientific research and clinical application.In particular,tissue engineered corneal scaffolds are the core components of tissue engineered corneas.It is the focus of current research on tissue engineering cornea to search for scaffolds with good biocompatibility,high safety and good biomechanical properties.In this paper,the recent research progress of tissue engineering corneal materials is reviewed.

A Systematic Review of Animal and Clinical Studies on the Use of Scaffolds for Urethral Repair

Replacing urethral tissue with functional scaffolds has been one of the challenging problems in the field of urethra reconstruction or repair over the last several decades. Various scaffold materials have been used in animal studies, but clinical studies on use of scaffolds for urethral repair are scarce. The aim of this study was to review recent animal and clinical studies on the use of different scaffolds for urethral repair, and to evaluate these scaffolds based on the evidence from these studies. Pub Med and OVID databases were searched to identify relevant studies, in conjunction with further manual search. Studies that met the inclusion criteria were systematically evaluated. Of 555 identified studies, 38 were included for analysis. It was found that in both animal and clinical studies, scaffolds seeded with cells were used for repair of large segmental defects of the urethra, such as in tubular urethroplasty. When the defect area was small, cell-free scaffolds were more likely to be applied. A lot of pre-clinical and limited clinical evidence showed that natural or artificial materials could be used as scaffolds for urethral repair. Urinary tissue engineering is still in the immature stage, and the safety, efficacy, cost-effectiveness of the scaffolds are needed for further study.

3D bioprinting of collagen-based materials for oral medicine

Oral diseases have emerged as one of the leading public health challenges globally.Although the existing clinical modalities for restoration of dental tissue loss and craniomaxillofacial injuries can achieve satisfactory therapeutic results,they cannot fully restore the original complex anatomical structure and physiological function of the tissue.3D printing of biological tissues has gained growing interest in the field of oral medicine with the ability to control the bioink component and printing structure for spatially heterogeneous repairing constructs,holding enormous promise for the precise treatment of oral disease.Particularly,collagen-based materials have been recognized as promising biogenic bioinks for the regeneration of several tissues with high cell-activating and biocompatible properties.In this review,we summarize 3D printing methods for collagen-based biomaterials and their mechanisms.Additionally,we highlight the animal sources of collagen and their characteristics,as well as the methods of collagen extraction.Furthermore,this review provides an overview of the 3D bioprinting technology for the regeneration of the pulpal nerve and blood vessels,cartilage,and periodontal tissue.We envision that this technique opens up immense opportunities over the conventional ones,with high replicability and customized function,which can ultimately promote effective oral tissue regeneration.

TGF-beta 1 Gene-Activated Matrices Regulated the Osteogenic Differentiation of BMSCs

Poly （lactic acid/glycolic acid/asparagic acid-co-polyethylene glycol）（PLGA-[ASP-PEG]） scaffold materials were linked with a novel nonviral vector （K）16GRGDSPC through cross linker Sulfo- LC-SPDP to construct a new type of nonviral gene transfer system. Eukaryotic expressing vector containing transforming growth factor beta 1 （pcDNA3-TGFβ1） was encapsulated by the system. Bone marrow stromal cells （BMSCs） obtained from rabbit were cultured on PLGA-[ASP-PEG] modified by （K）16GRGDSPC and TGF-β1 gene and PLGA-[ASP-PEG] modified by （K）16GRGDSPC and empty vector pcDNA3 as control. The expressions of osteogenic makers of the BMSCs cultured on the TGF-β1 gene-activated scaffold materials were found significantly higher than those of the control group （P〈0.05）. A brand-new way was provided for regulating seed cells to directionally differentiate into osteoblasts for bone defect restoration in bone tissue engineering.

Nano-apatite/Polymer Biocomposite for Tissue Engineering

A new kind of tissue engineering scaffold materials of nano-apatite （ NA ） and polyamide6 （ PA6 ） biocomposite was prepared by means of the co-solution method. The NA crystals uniforndy distribute in the composite with a size of 10-30 nm in diameter by 50-90 nm in length. The NA/ PA6 composite has good homogeneity and high NA content, and excellent mechanical properties close to those of natural bone. The porous 3-D scaffold has not only macropores, but also micropores on the walls of macropores with porosity of about 80% and the size of pore diameter of about 300μm made by injection foam. The biocomposite can be used for bone repair and as scaffolds in tissue engineering.

Experimental study on advanced bone regeneration by BMP-7 derived-peptide chitosan nanometer hydroxyapatite collagen biomimetic composite

Objective:To investigate the effect of BMP-7 derived-peptide chitosan nanometer hydroxyapatite biomimetic collagen composite on repairing rat critical-sized cranial defects.Methods:The chitosan nanometer hydroxyapatite collagen composite was prepared and the microcosmic appearance of the composite was observed by scanning electron microscope.The BMP-7 derived-peptide was introduced into the composite by vacuum adsorption.The released peptide content from the scaffold was detected using high performance liquid chromatography at different set times.Critical-sized cranial defects were created on both sides of the parietal bone in 24 adult Sprague-Dawley rats.The BMP-7 derived-peptide chitosan nanometer hydroxyapatite biomimetic collagen composites were implanted on the right side as experimental group and the left side was implanted with chitosan nanometer hydroxyapatite biomimetic collagen composites alone as control group.The rats of both groups were killed in batch respectively after 6 and 12 weeks.Macroscopic observation,three-dimensional reconstruction of computed tomography(CT)and histological observation were performed on these samples.Results:The results of scanning electron microscope showed that the surface of the scaffold was porous.The releasing character of BMP-7 derived-peptide belonged to slow release.The result of animal experiment showed that the BMP-7 derived-peptide chitosan nanometer hydroxyapatite biomimetic collagen composite could more effectively promote the repair of cranial bone defects comparing with the chitosan nanometer hydroxyapatite biomimetic collagen composite alone.The difference was statistically significant(p<.05).Conclusions:The BMP-7 derived-peptide chitosan nanometer hydroxyapatite collagen biomimetic composite can effectively promote bone regeneration of bone defects.The composite is a kind of ideal scaffold material for bone tissue engineering.

Three-dimensional breast cancer tumor models based on natural hydrogels:a review

Breast cancer is the most common cancer in women and one of the deadliest cancers worldwide.According to the distribution of tumor tissue,breast cancer can be divided into invasive and non-invasive forms.The cancer cells in invasive breast cancer pass through the breast and through the immune system or systemic circulation to different parts of the body,forming metastatic breast cancer.Drug resistance and distant metastasis are the main causes of death from breast cancer.Research on breast cancer has attracted extensive attention from researchers.In vitro construction of tumor models by tissue engineering methods is a common tool for studying cancer mechanisms and anticancer drug screening.The tumor microenvironment consists of cancer cells and various types of stromal cells,including fibroblasts,endothelial cells,mesenchymal cells,and immune cells embedded in the extracellular matrix.The extracellular matrix contains fibrin proteins(such as types Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅵ,and Ⅹ collagen and elastin)and glycoproteins(such as proteoglycan,laminin,and fibronectin),which are involved in cell signaling and binding of growth factors.The current traditional two-dimensional(2D)tumor models are limited by the growth environment and often cannot accurately reproduce the heterogeneity and complexity of tumor tissues in vivo.Therefore,in recent years,research on three-dimensional(3D)tumor models has gradually increased,especially 3D bioprinting models with high precision and repeatability.Compared with a 2D model,the 3D environment can better simulate the complex extracellular matrix components and structures in the tumor microenvironment.Three-dimensional models are often used as a bridge between 2D cellular level experiments and animal experiments.Acellular matrix,gelatin,sodium alginate,and other natural materials are widely used in the construction of tumor models because of their excellent biocompatibility and non-immune rejection.Here,we review various natural scaffold materials and construction methods involved in 3D tissue-engineered tumor models,as a reference for research in the field of breast cancer.

Selection of different endothelialization modes and different seed cells for tissue-engineered vascular graft

Tissue-engineered vascular grafts(TEVGs)have enormous potential for vascular replacement therapy.However,thrombosis and intimal hyperplasia are important problems associated with TEVGs especially small diameter TEVGs(<6 mm)after transplantation.Endothelialization of TEVGs is a key point to prevent thrombosis.Here,we discuss different types of endothelialization and different seed cells of tissue-engineered vascular grafts.Meanwhile,endothelial heterogeneity is also discussed.Based on it,we provide a new perspective for selecting suitable types of endothelialization and suitable seed cells to improve the long-term patency rate of tissue-engineered vascular grafts with different diameters and lengths.

Biomimetic Design of Oxidized Bacterial Cellulose-gelatin-hydroxyapatite Nanocomposites

Oxidized Bacterial Cellulose （OBC）-hydroxyapatite （HAp）-gelatin （Gel） nanocomposites were prepared by a biomimetic process. HAp nanocrystals were precipitated in a mixed solution ofNa2HPO4 （pH 9.2） and Gel solution at 37 ℃, and OBC was used to generate a three-dimensional （3D） network stent. The tensile strength of OBC-HAp-G was higher than 0.3 MPa, and the complete degradation time was approximately 90 d in Simulated Body Fluid （SBF）. Fourier transform infrared spectroscopy demonstrated that a coordinate bond had formed possibly between HAp and the cellulose hydroxyl. X-ray diffraction showed that both the oxidation of bacterial cellulose and an increase in Gel content induced the formation of tiny HAp crystallites during composite fabrication. Specific surface area and porosity measurements indicated that a low Gel concentration contributed to retention of porous structure. The Ca and P contents on the surface of materials increased initially and then decreased with an increase in Gel content, as measured by energy dispersive spectroscopy. From the thermogravimetric data, the increase in decomposition temperature suggested the formation of chemical bonds among OBC, HAp, and Gel. The above results suggest that the OBC-HAp-G0.3 composite is a potential bone scaffold material.