Research progress on the relationship between steroid-induced avascular necrosis of the femoral head and microRNA / 中国医师杂志

Steroid-induced avascular necrosis of the femoral head (SANFH) is the death of the femoral head caused by long-term use of glucocorticoid (GC). Its pathological manifestations are mainly trabecular bone collapse and increased empty bone lacunas, osteocyte apoptosis rate and autophagy rate. Its pathogenesis is complicated, and the exact pathogenesis is still unclear. MicroRNAs (miRNAs) are a group of endogenous, non-coding small RNAs with an average length of 23 nucleotides. They are responsible for negatively regulating gene expression after transcription by inhibiting target messenger RNAs (mRNAs). MiRNAs play an important role in physiological processes, including cell development, proliferation, differentiation, metabolism, migration and apoptosis. According to bioinformatics analysis, MiRNAs play an important role in regulating gene expression, and it is estimated that more than one-third of human genes are regulated by them. In the past few years, more and more miRNAs have been found to be related to osteonecrosis, such as regulating the proliferation and differentiation of mesenchymal stem cells and osteoblasts. This article aims to review the relationship between steroid-induced femoral head necrosis and miRNAs.

Study on the Formation of Bone Printed Scaffolds and Vascular Networks in 3D Bioprinting / 中华骨科杂志

Globally, more than 2 million bone grafts are performed every year for bone defects in orthopedics, neurosurgery, and dental procedures. Current treatment options include the use of grafts of human, animal or synthetic origin. In this case, autograft is the current gold standard. However, its quantity is limited, a second wound(donor site) needs to be created, and the risk of infection, pain, and morbidity increases. In recent years, the rise of tissue engineering and 3D bioprinting has provided a new idea for treating bone defects in patients. 3D bioprinting is a branch of the applications of "additive manufacturing" in biological tissue engineering. It can precisely control cells, personalize macro and micro structures as needed, and can be used in bone regeneration applications. The establishment of osteoblast scaffolds is the basis of 3D bioprinting, and hydrogels suitable for the growth of bone and cartilage are the basis of scaffold research. For this reason, domestic and foreign scholars have developed and researcheda variety of hydrogel scaffolds, and they have found that mixed hydrogels with multiple biological materials have more advantages than single-material hydrogels. For example, hydroxyapatite, alginate or hyaluronic acid is used as the main component to mix several or more bioprinting materials, and 3D printed bone scaffold formed after combining the required cells can promote bone growth and differentiation better than traditional scaffolds. As the printed structure becomes thicker, the diffusion of nutrients and oxygen becomes more and more difficult. This is especially true in the reconstruction of bone tissue and it is necessary to create an interconnected and effective vascular network. Therefore, the formation of blood vessels in the stent is indispensable. This article mainly reviews the step-by-step research progress of bone printing scaffold materials and vascular network formation in 3D bioprinting.