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BACKGROUND: Recent evidence suggests that autophagy, as a cell self-protection mechanism, plays an important role in regulating osteoblast function and maintaining osteoblast homeostasis. It has an important influence on the treatment and prognosis of periprosthetic osteolysis. OBJECTIVE: To provide new therapeutic ideas and potential therapeutic targets for periprosthetic osteolysis by summarizing previous studies on the autophagy mechanism of osteoblasts. METHODS: The first author used the computer to search the articles published from 2015 to 2022. In Chinese, the search terms “wear particles, periprosthetic osteolysis, osteoblasts, signal pathways, autophagy” were used to search the databases of CNKI, WanFang, and VIP. In English, the PubMed and Web of Science databases were retrieved with “wear debris, wear particles, peri*prosthetic osteolysis, PPOL, aseptic loosening, osteoblast, OB, signal path, autophagy”. A total of 98 articles were included according to the inclusion criteria. RESULTS AND CONCLUSION: In periprosthetic osteolysis, the changes in the autophagy ability of osteoblasts induced by wear particles play a key role in the development and outcome of the disease. A variety of signaling pathways jointly mediate autophagy in osteoblasts, among which the key pathways include AMPK/ULK1/mTOR, nuclear factor-κB, Pink1/Parkin, etc. AMPK, mTOR, and ULK1 can regulate each other and jointly maintain the stability of the autophagy level. There is a complex crosstalk between the nuclear factor-κB pathway and autophagy. PINK1 and Parkin are accumulated on the surface of the damaged mitochondrial membrane, inducing autophagy. There is crosstalk among multiple signaling pathways, which form a complex autophagy network under their mutual influence. Moreover, the activation of the same autophagy pathway in different cells may bring about completely opposite effects. Moderate autophagy induced by wear particles can reduce the apoptosis of osteoblasts, enhance their differentiation and mineralization ability, and improve the prognosis of osteolysis around the prosthesis. On the contrary, insufficient or excessive activation of autophagy will cause damage to osteoblasts and promote the progress of osteolysis. Therefore, targeting the level of autophagy of osteoblasts induced by wear particles through drugs or genes may be one of the directions for the treatment of periprosthetic osteolysis. [ABSTRACT FROM AUTHOR]

BACKGROUND: The Hippo-YAP signaling pathway is a signaling cascade that is highly conserved across species and has attracted widespread attention in the study of physiological cardiac hypertrophy. Studies have found that many pathways such as mechanical force, autophagy, and energy metabolism are involved in the regulation of exercise-induced cardiac hypertrophy. These pathways may interact with the Hippo-YAP signaling pathway after exercise, thereby affecting the formation and development of exercise-induced cardiac hypertrophy. OBJECTIVE: To summarize the effects of exercise on Hippo-YAP signaling pathway, and describe the potential mechanism of Hippo-YAP signaling pathway in regulating exercise-induced cardiac hypertrophy. METHODS: “Hippo-YAP signaling pathway, YAP/TAZ, exercise-induced cardiac hypertrophy, heart, exercise” were used as keywords in Chinese and English. Relevant literatures included in CNKI, PubMed, and Web of Science databases from 1983 to 2022 were retrieved, and 70 articles that met the screening criteria were reviewed. RESULTS AND CONCLUSION: Hippo-YAP signaling pathway is affected by exercise and has a certain regulatory role in exercise-induced physiological cardiac hypertrophy. (1) Hippo-YAP signaling pathway induces mechanical stimulation triggered by exercise, which leads to changes in the activity and expression of YAP/TAZ, and mediates the response of cardiomyocytes to mechanical signals. (2) Hippo-YAP signaling pathway regulates autophagy in cardiomyocytes and maintains the homeostasis, normal structures and physiological functions of cardiomyocytes during exercise. (3) Hippo-YAP signaling pathway may mediate the oxidation and glycolysis of energy substances during exercise-induced cardiac hypertrophy, and may also be affected by energy changes during exercise. (4) Hippo-YAP signaling pathway may strengthen the connection with some non-coding RNAs related to physiological cardiac hypertrophy under the action of exercise, and multiple non-coding RNAs may jointly regulate Hippo-YAP signaling. (5) Hippo-YAP signaling pathway interacts with the classic pathways of exercise-induced cardiac hypertrophy. Exercise promotes the signaling interaction between them and participates in the regulation of exercise-induced cardiac hypertrophy. (6) To deeply study the regulatory role of Hippo-YAP signaling pathway in exercise-induced cardiac hypertrophy will help deepen the understanding of exercise-promoting heart health, and provide new ideas and strategies for the clinical prevention and treatment of cardiac diseases and myocardial tissue construction. [ABSTRACT FROM AUTHOR]

BACKGROUND: Telomeres form special structures at the end of chromosomes in human cells, which have special functions and show a very close relationship with biological aging. Exercise can improve the activity of telomerases and protect the structure of telomeres, thus affecting human health. Shorter telomeres increase the incidence of diseases and decrease the survival rate. Therefore, telomeres are often considered as biological markers of cell aging and the “biological clock” that triggers aging. OBJECTIVE: Based on the relationship between telomeres and aging, to summarize and analyze the effect of exercise on telomeres and telomerases and to explore the mechanism of telomerase retardation by exercise, so as to provide theoretical basis and reference for anti-aging and health promotion by exercises. METHODS: We searched for relevant articles in CNKI, PubMed and Web of Science databases using the keywords of “telomeres, telomerase, exercise, senescence” in Chinese and English, and conducted preliminary screening of titles and abstracts according to inclusion criteria. After reading the full text, a total of 89 documents were included for further analysis. RESULTS AND CONCLUSION: Different exercises have different effects on telomeres. Exercise is positively correlated with telomere length, uncorrelated with telomere length, and has inverted U-shaped relationship with telemeter length. Exercise and telomerase activity are age-deviated. Suitable exercises can slow down the speed of telomere shortening, prevent the excessive consumption of telomeres, delay or prevent the occurrence of age-related diseases, and prolong life, but the mechanism has not been fully clarified. [ABSTRACT FROM AUTHOR]

BACKGROUND: Angiogenesis is a key component of bone reconstruction. Promoting bone vascularization thereby can accelerate bone repair. There are numerous research methods for promoting angiogenesis, and significant progress has been made in the field of bone defect repair in recent years. OBJECTIVE: To review several cutting-edge methods and developments in promoting angiogenesis and repairing bone defects in recent years, as well as their applications in bone tissue engineering. METHODS: The first author used the Chinese search terms “angiogenesis, osteogenesis, bone defect, tissue engineering, exosomes” and English search terms “angiogenesis, osteogenesis, bone defect, exosomes, vascularization” to find relevant publications in CNKI, WanFang, PubMed, and Web of Science databases. After screening and excluding articles irrelevant to the research purpose and repetitive articles, 69 articles were finally selected for review. RESULTS AND CONCLUSION: At present, promising results have been achieved in the bone defect remodeling research. Bone vascularization can be promoted by growth factors, delivery genes, biologically active ions, small molecule active peptides, and Chinese medicine monomers. Each has its own advantages and challenges, and faces different challenges. The synthesis of small molecule active peptides has low cost, high efficiency and safety, with obvious advantages. It has the potential to generate new ideas and methods for vascularization in bone tissue engineering. [ABSTRACT FROM AUTHOR]

BACKGROUND: Adipose-derived stem cells have become one of the popular seed cells in regenerative medicine due to abundant content and easy harvest. Adipose-derived stem cell exosomes are served as a bridge and link among adipose-derived stem cells and other cells and have the effects on regulating immune and inflammatory responses, promoting self-repair of damaged cells, and are considered as an alternative treatment for adipose-derived stem cells. OBJECTIVE: To review research progress and challenges in the adipose-derived stem cell exosomes regulating tissue regeneration. METHODS: CNKI, Wanfang database and PubMed, and Web of Science database were searched for related articles with the search terms of “adipose-derived stem cells; adipose stem cells; exosomes” in English and Chinese. After preliminary screening of articles based on inclusion and exclusion criteria, 70 articles with high relevance and reference value were retained for review. RESULTS AND CONCLUSION: Adipose-derived stem cell exosomes have shown the therapeutic potential in various diseases, such as skin wounds, neurodegenerative diseases, tumors, bone regeneration, kidney diseases, cardiovascular diseases, immune diseases, and fibrotic disease. [ABSTRACT FROM AUTHOR]

BACKGROUND: The exosomes are one of important active components of adult stem cells paracrine, providing the basis for stem cell “non-cellular” treatment. Exosomes from stem cells can play different roles in the wound through different mechanisms to promote the healing of diabetic wounds. OBJECTIVE: To summarize the main mechanism and application of stem cell derived exosomes in the treatment of diabetic wounds. METHODS: Computers were used to retrieve English databases such as PubMed database, Web of Science database, FMRS foreign language medical information resource retrieval platform, and Chinese databases such as CNKI and Wanfang Data Knowledge Service Platform. The retrieval scope was from the inception of the database to September 2020. The English and Chinese search terms were “stem cells, exosomes, wound healing, cell proliferation, neovascularization, inflammation, extracellular matrix, therapeutic use”. According to the inclusion and exclusion criteria, 66 articles were included and the results were analyzed. RESULTS AND CONCLUSION: (1) It is summarized that stem cell-derived exosomes can promote diabetic wound healing by regulating inflammation, promoting neovascularization, re-epithelialization and remodeling of extracellular matrix. (2) The application of stem cell-derived exosomes in diabetic wounds was listed. (3) The exosomes from stem cells can avoid the immune response of stem cells in the treatment of diabetic wounds, and the genetic material of stem cells carried by them is more widely regulated and more effective than that from ordinary cells in the treatment of diabetic wounds. (4) At present, the application of stem cell derived exosomes in diabetes wounds still has some problems, such as low purity, high cost of separation, low production efficiency, and the way to reach the target area, loss rate and diffusion efficiency. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hyaluronic acid is a natural polysaccharide and a common glycosaminoglycan in human body. It has the highest concentration in eyes and joints. It is made into hydrogels because of its biocompatibility, degradability, and low immunogenicity, and is widely used in tissue engineering. OBJECTIVE: To introduce the characteristics of various hyaluronic acid composite hydrogels and their application in the repair of cartilage damage caused by osteoarthritis. METHODS: CNKI and Wanfang databases were searched with the key words of “hyaluronic acid, hydrogel, cartilage repair, osteoarthritis” in Chinese. PubMed and Web of Science databases were searched with the key words of “hyaluronic acid, hydrogel, cartilage repair, osteoarthritis” in English. The articles published from January 1995 to July 2020 were searched and further analyzed and summarized. RESULTS AND CONCLUSION: The excellent biological properties of hyaluronic acid hydrogel have made it widely studied in the cartilage repair of osteoarthritis, especially through the combination of biological factors, natural materials, synthetic materials, 3D printing technology, polypeptides, mechanical stimulation, etc., which improved the performance of hyaluronic acid hydrogel and promoted its application in cartilage tissue engineering. Although hyaluronic acid composite hydrogels have been studied more, with the comprehensive development of chemistry, materials, physics, biology and other disciplines in the future, a deeper understanding of the degradation mechanism of hyaluronic acid hydrogels and an exploration of the cartilage damage mechanism in osteoarthritis, the hyaluronic acid composite hydrogel is expected to be designed with high efficiency, no side effects and more suitable for cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

BACKGROUND: Keloid is a benign skin tumor with excessive proliferation of fibroblasts and deposition of collagen after trauma. Vascular occlusion, inflammation, fibroblast proliferation and collagen secretion in keloid tissues all lead to tissue hypoxia, which plays an important role in the pathogenesis and prognosis of keloids. OBJECTIVE: To review the research progress of hypoxia-inducible factor 1 alpha (HIF-1α) in the tumor-like characteristics of keloid. METHODS: CNKI, VIP, WanFang, PubMed, Biosos Preview, and Web of Science databases were searched for relevant articles from their inception to November 2020. The retrieval key words were “keloids, HIF-lα; radioresistance” in Chinese and English, respectively. After reading the title, abstract and full text, 104 articles that met the selection criteria were finally selected. RESULTS AND CONCLUSION: The hypoxic microenvironment inhibits the degradation of HIF-1α, and increased HIF-1α induces several biological behaviors in keloid tissue similar to malignant tumors, including epithelial-mesenchymal transition, angiogenesis, glycolysis, radioresistance, and recurrence after radiation. These pathophysiological processes in turn exacerbate tissue hypoxia and increase HIF-1αexponentially, thereby forming a vicious circle. Current treatments for keloids mainly focus on surgical resection combined with radiotherapy. HIF-1α targeting therapies, such as hyperbaric oxygen therapy, can significantly improve the hypoxic environment of keloid tissue, promote wound healing, and reverse the tumor-like properties of keloid fibroblasts. However, there are few studies on the treatment of keloids with hyperbaric oxygen therapy combined with radiotherapy, and the clinical treatment of keloids with HIF-1α as the target is still under exploration. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the improvement of the medical level and people’s higher requirements for the quality of life, the quality and requirements for cartilage repair in the clinic are getting more and more, but traditional repair methods cannot regenerate cartilage with good biological properties. OBJECTIVE: To review the research progress of autologous chondrocyte implantation in recent years, and to analyze its development process, basic science, indications, contraindications, surgical techniques, clinical efficacy and limitations, and look forward to the development trend of this field. METHODS: A computer-based online search of CNKI, PubMed, Web of Science databases, and Google Scholar was performed to retrieve papers published during 1990-2020 with the search terms “autologous chondrocyte implantation, cartilage defect, techniques, clinical effect, indications, contraindications, defect size, treatment after initial failure, return to sports, age, magnetic resonance imaging, limitation” in English and Chinese. The document types include treatise, reviews, case reports, and meta-analysis. A total of over 1 000 papers were retrieved, and 52 of them were included in the final analysis. RESULTS AND CONCLUSION: Autologous chondrocyte transplantation first appeared for the treatment of knee cartilage defects in the late 1980s. The first generation of autologous chondrocyte transplantation used periosteal patches to seal the cultured chondrocytes in the defect. Due to the proliferation of periosteal grafts, second-generation autologous chondrocyte transplantation used collagen membrane patches instead of periosteal patches. The third generation of autologous chondrocyte transplantation used three-dimensional culture technology to improve cell delivery, allowing minimally invasive implantation, which could regenerate normal cartilage structure with accelerating patient recovery. Autologous chondrocyte transplantation was an effective method to treat high tibia or femoral cartilage defects, but it must solve the problems consisting of coronal force line, ligament laxity, and meniscus injury. Because of the graft needing a long time to mature, patients needed a specific rehabilitation plan to return to the sport, which assisted the injured patients in restoring strength and neuromuscular coordination as much as possible before the graft was fully mature. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the development of bone tissue engineering, the role of scaffold materials has become more and more important. Polycaprolactone and its composite materials have also increasingly attracted researchers to become one of the research highlights in this field. OBJECTIVE: To introduce the basic properties and synthesis methods of polycaprolactone, to summarize the research status of polycaprolactone and its composite materials in the field of bone tissue engineering, and to prospect the future development and research direction. METHODS: These articles published from 1950 to 2020 in Web of Science database were retrieved by using the search terms “PCL, PCL composites, bone tissue engineering, scaffold, bone, PCL synthesis”, taking “and” as the logical combination relationship. Totally 253 articles were initially obtained, and finally 52 articles were reviewed and analyzed after careful reading and selection. RESULTS AND CONCLUSION: (1) Pure polycaprolactone materials have certain shortcomings in bone tissue engineering. Due to their easy chemical modification and physical modification, polycaprolactone composite undoubtedly has become one of the candidate materials for bone tissue engineering scaffolds. (2) Due to the excellent solubility and thermal properties of polycaprolactone, it can be applied to a variety of scaffold preparation technologies. The appropriate scaffold preparation technology can be selected according to the application site. A variety of scaffold preparation technologies also broaden the application field of polycaprolactone, and there are also developed some novel technologies, so scaffold preparation technology should also attract the attention researchers. (3) For the modification direction of polycaprolactone, the modification of inorganic substances and natural or synthetic polymers has received extensive attention. (4) In terms of experimental research methods, researchers should pay attention to introducing more kinds of experimental cells and experimental models in accordance with clinical needs. [ABSTRACT FROM AUTHOR]