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Objective:To explore the problems of seed cells and biological scaffolds in spinal cord tissue engineering, and review the recent experimental research. Methods:Related literatures were searched in CNKI, Wangfang data, PubMed and Web of Science from establishment to March, 2021, and the problems and progress of seed cells, biological scaffolds and their combination were reviewed. Results:The problems of seed cells are carcinogenicity, immune rejection, ethics, low survival rate and differentiation rate after transplantation, and current researches focus on exploring new cell types, gene transfection, cell co-transplantation and pretreatment before transplantation. The problems of biological scaffold are that a single material selection cannot meet different needs, and the traditional technology cannot simulate the internal structure of spinal cord well. There were more researches focusing on new composite materials and new technology. The core problem of their combination is that the effects of different cell and scaffold combinations are different, and the current researches are mostly devoted to the continuous exploration of suitable composite mode, and try to introduce biological agents and other factors. Conclusion:Spinal cord tissue engineering has the potential to completely change the therapeutic pathway of spinal cord injury. Current experimental researches mainly base on solving the problems of seed cells and biological scaffolds of spinal cord tissue engineering, and further explore the appropriate composite mode of seed cells and biological scaffolds, so as to provide more basic evidence for its clinical application.
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@#In recent years, pulp regeneration has become a research hotspot in the field of stomatology. 3D printing can realize precise control of structure and shape of scaffolds, which provide basis for seed cell adhesion and growth factor release. The 3D printing "pulp complexes" constructed by 3D printing scaffolds for tissue engineering provides a new direction for pulp regeneration research. This paper reviews the applications of 3D printing technology in pulp regeneration. The results of literature review showed that the scaffold materials, seed cells and growth factors in the 3D printing "pulp complexes" all play an important role in the pulp regeneration research. Among them, the scaffold materials act as carriers to load seed cells and growth factors and provide a suitable microenvironment for them. The common seed cells such as dental pulp stem cells, stem cells from apical papilla and stem cells from the human pulp of exfoliated deciduous teeth can provide the cellular basis for pulp regeneration. Moreover, the introduction of growth factors can further support the differentiation of pulp tissue and the reconstruction of pulp vessels and promote pulp regeneration. At present, the 3D printing "pulp complexes" in the study of dental pulp regeneration has made some progress and can induce the formation of pulp-like tissues in the laboratory. However, preparing 3D-printing "pulp complex" with good biological activity, which integrates biomimetic blood vessels and nerves to supply oxygen and nutrients to the cells in the root canal, remains a huge challenge and still needs further exploration and research.
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BACKGROUND: Functional tracheal reconstruction remains a surgical challenge due to the lack of satisfactory tracheal substitutes. OBJECTIVE: To review the research hotspot, clinical application, and main obstacles of tissue-engineered trachea METHODS: A computer-based search of PubMed, Medline, and WanFang databases was performed to retrieve relevant articles published from 2004 to 2019 with the search terms “3D printing, tissue-engineered trachea, trachea reconstruction, tracheal replacement” in English and Chinese. A total of 47 literatures were included in the final analysis. RESULTS AND CONCLUSION: At present, the methods of tracheal reconstruction mainly include artificial tracheal transplantation, allotransplantation, autologous tissue transplantation and tissue-engineered tracheal transplantation. Artificial trachea transplants often fail due to rupture, infection and narrowing of the trachea. Allotransplantation requires long-term immunosuppressive therapy, and death is often caused by necrosis and infection because of insufficient angiogenesis after transplantation. Autogenous tissue has limited ability to replicate the structure and function of the trachea and also has surgical trauma. Tissue-engineered trachea can simulate the biological structure and function similar to natural trachea by selecting suitable scaffold materials and implanting seed cells evenly in the scaffold. It seems to be an ideal tracheal substitute. An intact tracheal scaffold was prepared with biodegradable material using 3D printing technology combined with tissue engineering technology and then implanted into the tissue-engineered trachea cultured with mesenchymal stem cells. This provides a new approach to long-segment tracheal defect reconstruction.
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BACKGROUND: With the development of tissue engineering, the repair and regeneration of disc becomes possible. Decellularized extracellular matrix is an important means for disc regeneration. OBJECTIVE: To review and summarize the processing, quality control and application of decellularized matrix materials applied in intervertebral disc regeneration in recent years and put forward the prospect. METHODS: PubMed, Web of Science and CNKI databases were searched for the articles concerning decellularized methods and decellularized matrix repairing intervertebral disc with the search terms of “intervertebral disc, decellularization, extracellular matrix, scaffold material, tissue engineering” in English and Chinese, respectively. After screening based on the inclusion and exclusion criteria, the articles with high relevance were included for review. RESULTS AND CONCLUSION: The decellularized tissue-engineered intervertebral disc aims to maintain the physiologically relevant bioactivators to a great extent, improve mechanical properties and biocompatibility, and reduce immunogenicity. The decellularized matrix material can simulate the microenvironment of the extracellular matrix in the intervertebral disc. As a cell carrier, it can well induce the differentiation of seed cells, which has achieved certain progress in the repair of intervertebral discs. However, further studies need to address the following issues: proper porosity of decellularized matrix materials, immunological rejection, implant ways in vivo and repair effect.
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Objective: To review the literature on the research status of vascularization of tissue engineered peripheral nerve so as to provide the theoretical basis for the vascularization of tissue engineered peripheral nerve. Methods: The literature related to the vascularization of peripheral nerve tissue engineering in recent years was reviewed and summarized according to the five aspects of promoting vascularization: local microenvironment and blood supply characteristics of peripheral nerve regeneration, scaffold material modification, seed cells, autologous vascular bundle implantation, and pro-vascular factors. Results: Tissue engineered peripheral nerve has brought a new hope for the repair of peripheral nerve injury, but the repair effect of large nerve defects is not good, which is mainly related to the degree of vascularization of the nerve grafts. So it is particularly important to promote the early vascularization of tissue engineered peripheral nerve. Previous studies have mainly focused on the four aspects of scaffold material modification, seed cells, autologous vascular bundle implantation, and angiogenesis related factors. Recent studies show that the combination of the above two or more factors in the tissue engineered peripheral nerves can better promote the vascularization of tissue engineered peripheral nerves. Conclusion: Promoting early vascularization of tissue engineered peripheral nerves can provide timely nutritional support for seed cells on the scaffold, promote axon growth and nerve regeneration, and facilitate the repair of large peripheral nerve defects in clinical practice.
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Tissue engineering is a comprehensive discipline that combines materials science, life sciences, and engineering to repair, and improve and preserve damaged tissues or organs through cell or tissue reconstruction. In recent years, with the rapid development of tissue engineering technology, tissue engineering trachea has gradually become a new approach to tracheal replacement therapy. However, due to the slender and periodic distribution of the blood vessels supplying the trachea, tracheal grafts cannot obtain sufficient blood supply to maintain its demand, making its vascularization problem one of the major obstacles to the development of tissue engineering trachea. In the construction of tissue engineering trachea, the vascularization strategy of seed cells, tracheal scaffold and growth factors have gradually become the focus of research. In this paper, the current researches on tissue engineering tracheal vascularization were reviewed.
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Tissue engineering skin has a wide application prospect on the clinical treatment of all sorts of skin defect, especially large area burn. The shortage of seed cells and their function improvement are the main problems in this field. The existing seed cells of tissue engineering skin are difficult to meet the needs of clinical application due to the limitations of acquisition, proliferation, and aging. Subsequently, the generation of induced pluripotent stem cells (iPSCs) provides a safe and efficient cell source for tissue engineering skin. Our article focuses on the origin of iPSCs and its characteristics of differentiating into keratinocytes, fibroblasts, melanocytes, vascular smooth muscle cells, nerve cells, and hair follicle, and discusses the main problems and prospects of iPSCs in establishment of tissue engineering skin and application in wound repair.
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Tissue engineering can regenerate damaged tissues and restore the biological functions by cell or tissue reconstruction,and is becoming a promising method for trachea replacement.Seed cells,cell growth factors and tracheal scaffolds are the three major elements of tissue engineering trachea,as a result researchers have paid a lot of attention to find ideal seed cells.Mesenchymal stem cells (MSCs) are a kind of stem cells with high self-renewal ability and muhi-directional differentiation potential.MSCs are widely distributed in bone marrow,umbilical cord,adipose tissue,myocardial tissue,brain,muscle and skin,and can differentiate into a variety of cells,including osteocytes,chondrocytes,adipocytes and neurocytes.MSCs have the characteristics of high proliferation ability,wide differentiation range and immunomodulatory function,which can be used to repair damaged tissue.These advantages make the MSCs an ideal candidate of seed cells for tissue engineering trachea.This review mainly summarized the application of MSCs in tissue engineering trachea.
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As the human population ages and the life expectancy increases,tendon injuries will become more prevalent,especially among young individuals.Though the traditional operative therapy for tendon lesion can relieve the suffering of patients,the functional reconstruction is usually not optimistic.Tissue engineering is an advancing field,as the technology of construction in vitro and application in vivo matures,that can provide a more promising approach for tendon repair without tendon autograft.Challenges and future directions in the field of tendon tissue engineering focusing on four key parameters:seed cells,novel scaffolds,and mechanical stimulation.Recently,the discovery of TDSCs (tendon-derived stem cells) provides new ideas for the selection of seed cells and effect of mechanical stimulation on the tendon tissue engineering has become a hot spot.This article provides a review of recent progress in research about seed cells,scaffolds and mechanical stimulation for tendon engineering,and also speculates on the development in the future.
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Objective To investigate the chondrogenic feasibility of the human umbilical cord derived mesenchymal stem cells (hUCMSCs)as cartilage tissue engineering seed cells ,type Ⅱ collagen composite glycosaminoglycan scaffold as the cellular carrier and cell‐scaffold complex .Methods The type Ⅱ collagen composite glycosaminoglycan scaffolds was prepared .The pore diameter , porosity and hydrophilia of scaffold materials were observed and measured by electronic microscope .The corresponding histological analysis on the scaffold materials was performed .hUCMSCs of P3 generation were cultured and identified .The hUCMSCs suspen‐sion was inoculated in the type Ⅱ collagen composite glycosaminoglycan scaffold for conducting culture without adding inducer .The samples were taken out after 3 weeks and performed the toluidine blue and safranin O staining ,type Ⅱ collagen immunohistochemi‐cal staining and SEM scanning .Results hUCMSCs of P3 generation highly expressed the mesenchymal cell marker CD29 and CD105 ,while hardly expressed endothelial cells of CD34 and hematopoietic cell markers .The type Ⅱ collagen composite glycosami‐noglycan scaffold presented white porous foam like ,the porosity was (91 .8 ± 2 .17)% ,the average pore diameter was 110‐230 μm , which was homogeneously distributed and had interpenetration .The scaffold showed good hydrophilicity with the water absorption expansion rate of (213 .71 ± 1 .31)% .The scaffold staining of toluidine blue ,safranin O and type Ⅱ collagen was positive .The car‐tilage‐like tissues were observed ,and gradually increased in the surface of cell‐scaffold complex along with culture ,which were posi‐tive in Toluidine blue ,safranin O and type Ⅱ collagen staining ,the electronic microscopic observation displayed that the cells were actively proliferated in the scaffold ,closely adhered with the materials ,the cartilage‐like cells and a large number of peripheral colla‐gen fibers with zigzag connection could be seen .Conclusion Compositing hUCMSCs and type Ⅱ collagen composite glycosamin‐oglycan scaffold could construct tissue‐engineering cartilage in vitro without induction ,which lays a certain experimental foundation for the repair of cartilage damage .
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[ ABSTRACT] AIM:To investigate the biological characteristics of newborn rabbit tracheal chondrocytes in vitro. METHODS:Newborn rabbit tracheal chondrocytes were obtained by the method of enzyme digestion, and then cultured in monolayer in vitro.Morphological and growth observations were performed under inverted phase contrast microscope.The ultrastructures of the cells were observed under scanning electron microscope and transmission electron microscope.The bi-ological characteristics of secreted extracellular matrix components were detected by real-time PCR, immunocytochemistry staining and toluidine blue staining.RESULTS: Newborn rabbit tracheal chondrocytes isolated and cultured in vitro showed short triangular or irregular shapes, and adherent growth very well.The ultrastructures of the cells showed pore and abundant cytoplasm and organelles, with a lot of protein secretions in the cells.The chondrocytes expressed the mRNA of collagen I, collagen II and proteoglycans, mainly collagen II and proteoglycans.Immunocytochemistry staining showed col-lagen II and SOX9 positive, and collagen I weakly positive.Toluidine blue staining was also positive.CONCLUSION:Enzyme digestion and monolayer culture are suitable method to obtain newborn rabbit tracheal chondrocytes.These cells, secreting extracellular matrix components, are able to be selected as seed cells for tissue engineering of trachea in vitro, and used to study the therapeutic method for neonatal rabbit tracheal stenosis.
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Researching tissue engineered biliary duct aims to repair,replace and regenerate damaged or diseased bile duct by using the in vitro constructed tissues.In this article,we reviewed the cell sources,and scaffolds and the current status of the construction of the tissue engineered biliary duct in tissue engineering.and discussed the existing obstacles and development trends.Tissue engineered biliary duct has an intriguing perspective for the replacement therapy,but it is still at an early stage,its true value remains to be evaluated.
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Objective To explore the feasibility of using human umbilical cord derived mesenchymal stem cells as seed cells to repair sciatic nerve defects of rats by tissue engineering methods. Methods Mesenchymal stem cells from human umbilical cord were cultured and induced into neuron-liked cells,which were co-cultured with acellular basal lamina tube to construct tissue engineering nerve;models of sciatic nerve defects 10 mm in length were set up with thirty healthy adult SD rats and were divided randomly into 3 groups:tissue engineering nerve group (group A, compound of human umbilical cord derived mesenchymal stem cells and acellular basal lamina tube), pure acellular basal lamina tube group (group B), and autogenous nerve bridging group (group C). Evaluation of electrophysiological and histological results was carried out 10 weeks after operation. Results The engineering nerve group had good result in nerve regeneration which was close to the effect of autogenous nerve transfer group (group A), and much better than the effect of pure acellular basal lamina tube group. Conclusion Engineering nerves from human umbilical cord derived mesenchymal stem cells can effectively repair 10 mm defects of sciatic nerve.
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The research of bone tissue engineering provides new thought and method to repair mass bone defect. Neovascularization plays a significant role in bone repair. This article reviews the advancements of the growth factors, seed cells and scaffolds in vascularization of tissue engineering bone, then raise the problems to solve and the prospect of future research.
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The tissue engineering heart valve(TEHV) is a kind of procthetic valve that possesses the characteristics of living, self-repair and proliferation. Owing to the specific properties that are the better hemodyna-mics, low or even no immunological reaction, no need for long-time anticoagulation therapy and longer durability, the ideal TEHV can overcome the drawback of current available valve substitutes which are mechanical prostheses and biological heart valves. In this paper we reviewed the recent development of the TEHV in such aspects, as biomaterial, cultivating environment, seed cells and so on. In addition, we briefly introduced the perspective of using human embryonic stem cells as the source for seed cells in TEHV.
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The inhibitory environment and loss of axonal connections after spinal cord injury pose many obstacles to regenerating the lost tissue.Cellular therapy provides a means of restoring the cells lost to the injury and could potentially promote functional recovery after such injuries.This review presents a summary of the various types of cellular therapy used to treat spinal cord injury.A wide range of cell types have been investigated for such uses and the advantages and disadvantages of each cell type are discussed along with the research studying each cell type.Based on the current research,suggestions are given for future investigation of cellular therapies for spinal cord regeneration.
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Tissue engineering has been one of the most challenging and rapidly developing frontier fields of science in the recent 20 years. Being referred to as “a medical revolution of far-reaching significance”, “a new epoch of regenerative medicine”, it signals the coming of a period of reproduction of regenerative tissue and organs. It has drawn intensive attention and support from medical circles and governments all over the world because of its advantages in trauma repair, functional reconstruction, life saving and improving quality of life, as well as its huge social and economic values. Products of tissue engineered skin and cartilage with approval of the American FDA have been available. Hundreds of tissue engineering companies and research centers have been set up both abroad and at home. It is now possible to construct tissue-engineered tissues. Moreover, projects of complex organ construction by means of tissue engineering is being carried out vigorously in the world. Some tissue-engineered tissues have been put into trial use in clinic and resulted in encouraging outcome. All these forecast a bright and promising prospect for tissue engineering. As a new branch of science and technology that involves multiple specialties and fields, however, it is still at its initial stage. Many fundamental scientific problems are to be explored, and many technical difficulties to be overcome. Hope and difficulty coexist; opportunity and challenge stand side by side. We should seize the opportunity and meet the challenge with our creative and strenuous efforts to make tissue engineering benefit human beings as early and much as possible.
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Acute cartilage injury is one of the most common disorders in orthopaedic clinics.Articular cartilage is known to have a limited capacity to repair or regenerate itself. The disorder is difficult to be dealt with, usually affects the function of joint and may induce the onset of osteoarthrosis.This will result in great economic burdens on the patients and their family and greatly degrade the patient s quality of life. The recent progress in researches on seed cells, culture methods, biological material has provided a new method to repair the acute injury of articular cartilage and thus may solve many problems. The article introduces new advances in seed cells and their culture methods in cartilage tissue engineering.