Summary

The process of bone defect repair is accompanied by a complex local immune response. An imbalance in the bone immune microenvironment often inhibits the formation of blood vessels and new bone tissue. How to regulate immune cell responses at the bone defect site using biomaterials has become an urgent issue in the field of bone tissue regeneration. Similarly, achieving long-term controlled release of magnesium ions is also a technical challenge in this area. In this study, a temperature-sensitive HPCH@HA composite hydrogel loaded with nano magnesium oxide was developed, using the hydrogel matrix to achieve slow release of magnesium ions. In vitro experiments confirmed that this material can induce macrophages to polarize toward the M2 phenotype while activating T lymphocytes, thereby further promoting stem cell osteogenic differentiation and endothelial cell angiogenesis.

The study further conducted in vivo validation using animal defect models, confirming that this composite temperature-sensitive hydrogel can remodel the local microenvironment at the defect site through bone immune regulation, simultaneously driving angiogenesis and bone tissue regeneration, ultimately achieving in situ repair of bone defects. Unlike previous studies that focused only on macrophage regulation of bone regeneration, this work also considers the role of T lymphocytes in the bone immune microenvironment, offering new ideas for the development of injectable bone repair hydrogels and the design of bone immune regulation strategies.

Reference:

DOI: 10.1016/j.bioactmat.2025.08.007