Zhu Yanlun, Deng Shuai, Ma Zhijie, Kong Lingzhi, Li Haiyan, Chan Hon Fai
Shanghai Jiao Tong University Affiliated Sixth People's Hospital, School of Biomedical Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, People's Republic of China.
Institute for Tissue Engineering and Regenerative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region of China.
Biomed Mater. 2021 Mar 8;16(4). doi: 10.1088/1748-605X/abe80a.
Akermanite (Aker) has been widely used for bone regeneration through regulating osteogenesis of bone marrow-derived mesenchymal stem cells (BMSCs). Previously, we developed an injectable Aker/sodium alginate (Aker/SA) hydrogel to facilitate bone regeneration. However, the effect of this injectable hydrogel on theresponse, particularly the inflammatory response, has not been fully understood. Here, to elucidate the response following the implantable of Aker/SA hydrogel, we investigated the interaction among Aker/SA hydrogel, inflammatory cells and cells involved in bone regeneration (BMSCs). Specifically, we cultured macrophages (RAW 264.7 cell line) with the extract liquid of Aker/SA and assessed their phenotypic changes. Subsequently, BMSCs (2 × 10cells per 24 well) were cultured with different conditioned media including that of Aker/SA hydrogel-activated macrophages to investigate their effect on cell migration. Finally, Aker/SA hydrogel was injected subcutaneously (1 × 10cells ml) in rat to verify its effect. Theresults indicated that Aker/SA hydrogel activated macrophages towards M2 phenotype and stimulated macrophages to express anti-inflammatory factors. In addition, the conditioned medium collected from Aker-activated macrophages could accelerate the migration of BMSCs in 24 h. Consistent with theresults, when the Aker/SA hydrogel was injected subcutaneously, more M2 macrophages could be observed than when the SA solution was injected after 7 d. Besides, when BMSCs were delivered via subcutaneous injection, more BMSCs were recruited by the Aker/SA hydrogel than the SA solution. All these results suggest that the Aker/SA hydrogel can modulate the immune environment at the implantation site and subsequently recruit BMSCs, which can be one of the mechanisms through which the Aker/SA hydrogel accelerates new bone formation.
钙黄长石（Aker）已通过调节骨髓间充质干细胞（BMSC）的成骨作用被广泛用于骨再生。此前，我们开发了一种可注射的钙黄长石/海藻酸钠（Aker/SA）水凝胶以促进骨再生。然而，这种可注射水凝胶对反应，尤其是炎症反应的影响尚未完全了解。在此，为了阐明Aker/SA水凝胶植入后的反应，我们研究了Aker/SA水凝胶、炎症细胞和参与骨再生的细胞（BMSC）之间的相互作用。具体而言，我们用Aker/SA的提取液培养巨噬细胞（RAW 264.7细胞系）并评估其表型变化。随后，将BMSC（每24孔2×10个细胞）与不同的条件培养基一起培养，包括Aker/SA水凝胶激活的巨噬细胞的条件培养基，以研究它们对细胞迁移的影响。最后，将Aker/SA水凝胶皮下注射（1×10个细胞/毫升）到大鼠体内以验证其效果。结果表明，Aker/SA水凝胶将巨噬细胞激活为M2表型并刺激巨噬细胞表达抗炎因子。此外，从Aker激活的巨噬细胞收集的条件培养基可在24小时内加速BMSC的迁移。与结果一致，当皮下注射Aker/SA水凝胶时，7天后观察到的M2巨噬细胞比注射SA溶液时更多。此外，当通过皮下注射递送BMSC时，Aker/SA水凝胶比SA溶液招募到更多的BMSC。所有这些结果表明，Aker/SA水凝胶可以调节植入部位的免疫环境，随后招募BMSC，这可能是Aker/SA水凝胶加速新骨形成的机制之一。
