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BACKGROUND: Femoral head necrosis brings a serious burden to patients and the society. The existing hypotheses cannot fully explain the mechanism of the femoral head necrosis. However, there is no doubt that the dysfunction of bone microcirculation system is its pathological basis. Given the importance of microcirculation during femoral head necrosis, recent studies indicate that bone microvascular endothelial cell injury exerts a crucial effect on the pathogenesis of femoral head necrosis. OBJECTIVE: To analyze the action mechanism of bone microvascular endothelial cells for treatment of femoral head necrosis, and to focus on the prospect of improving microcirculation and promoting osteogenesis based on bone microvascular endothelial cells, so as to treat femoral head necrosis. METHODS: “Necrosis of femoral head; bone microvascular endothelial cells; microcirculation disorder; bone tissue engineering technology; microRNAs” were used as Chinese and English keywords. Totally 220 related articles were obtained by searching on CNKI (China National Knowledge Infrastructure), Wanfang database, and PubMed database. Insufficient timeliness, vague conclusions, and repetitive articles were excluded by reading the titles, abstracts and part of the content. Finally, 63 articles that met the inclusion criteria were included for review. RESULTS AND CONCLUSION: (1) The impaired angiogenesis, abnormal apoptosis, thrombosis and fat embolism caused by the dysfunction of bone microvascular endothelial cells are all involved in the occurrence and development of avascular necrosis of the femoral head. (2) Traditional Chinese medicine, bone tissue engineering technology, transfection-based method, and microRNAs can be employed to prevent and treat avascular necrosis of the femoral head by promoting angiogenesis, suppressing apoptosis and vascular embolism. (3) Combined transplantation of microvascular endothelial cells and bone marrow mesenchymal stem cells is one of the most promising strategies for the treatment of femoral head necrosis, but the optimal ratio between co-grafts and scaffolds with good biocompatibility and cultured cells needs further research. (4) For gene transfection, the transcriptional regulation mechanism of target gene in host cells has not been fully studied. In addition, there are few related clinical trials, and the therapeutic effect needs to be further verified. [ABSTRACT FROM AUTHOR]

BACKGROUND: Treatments for bone defects have always been a global problem, and there are certain drawbacks in most of traditional treatment technologies that cannot meet the demand of patients. The emergence of tissue engineering has a strong theoretical support, and brings a hope for the majority of bone defect patients. However, this technology cannot yet be widely used in the clinical practice, which may encounter the bottleneck and difficulty. OBJECTIVE: To discuss the research progress in tissue engineering for treating bone defect from the three aspects and to summarize the existing problems in tissue engineering, with emphasis on the rapid vascularization in tissue engineering. METHODS: CNKI, CM, PQDD, and PubMed were searched for relevant literatures published from 2000 to 2020 using the keywords of “tissue engineering, scaffold materials, seed cells, growth factor” in Chinese and English, respectively. A total of 180 related literatures were initially retrieved, and only 36 articles were included for review, after excluding outdated, ambiguous, and repetitive literatures through reading the titles, abstracts and the contents. RESULTS AND CONCLUSION: Bone tissue engineering technology is used to treat bone defects by simulating the bone tissue growth. Theoretically, the three elements of tissue engineering technology, including seed cells, scaffold materials, cytokines, have been greatly developed, which can basically meet the demand of patients and doctors. However, early-stage rapid vascularization maybe limits the popularization of tissue engineering in clinical practice. By analyzing the formation of new blood vessels and summarizing the methods for early-stage rapid vascularization, we intend to establish a composite scaffold by co-culture of endothelial progenitor cells and bone marrow mesenchymal stem cells. The scaffold with appropriate porosity can simulate the in vivo microenvironment, and build a space for cells to function normally and for blood vessels to grow in appropriate pores, which is expected to solve the problem regarding early vascularization. [ABSTRACT FROM AUTHOR]