MiR-144-5p, an exosomal miRNA from bone marrow-derived macrophage in type 2 diabetes, impairs bone fracture healing via targeting Smad1

Dong Zhang,Aixi Yu,Hairen Chen,Chao Jian,Zonghuan Li,Siyuan Huang,Yifan Wu

doi:10.1186/s12951-021-00964-8

Abstract

BackgroundPatients with diabetes have an increased risk of nonunion and delayed union of fractures. Macrophages have been shown as a key player in diabetic complications. However, it remains obscure how diabetic milieu affects macrophage-derived exosomes and its implications on osteogenic differentiation of BMSCs. In this study, we aim to define the impact of diabetic milieu on macrophage-derived exosomes, role of extracellular vesicles in intercellular communication with BMSCs, and subsequent effects on osteogenic differentiation and fracture repair.ResultsThe osteogenic potential and the ability of fracture repair of exosomes derived from diabetic bone marrow-derived macrophages (dBMDM-exos) were revealed to be lower, as compared with non-diabetic bone marrow-derived macrophages (nBMDM-exos) in vitro and in vivo. Interestingly, miR-144-5p levels were sharply elevated in dBMDM-exos and it could be transferred into BMSCs to regulate bone regeneration by targeting Smad1. In addition, the adverse effects of dBMDM-exos on the osteogenic potential and the ability of fracture repair were reversed through the suppression of miR-144-5p inhibition in vitro and vivo.ConclusionsThe results demonstrated an important role of exosomal miR-144-5p in bone regeneration, offering insight into developing new strategy for the improvement of fracture healing in patients with diabetes mellitus.Graphic

Highlights

Patients with diabetes have an increased risk of nonunion and delayed union of fractures
These exosomes were co-cultured with bone mesenchymal stem cells (BMSCs), the RT-qPCR results showed that BMSCs treated with dBMDM-exos exhibited significantly increased expression of miR-144-5p (Fig. 5f ). These results suggest that miR-144-5p is elevated in dBMDM-exos and dBMDM-derived exosomal miR-144-5p can be internalized by BMSCs
The results demonstrated that the mRNA and protein levels of RUNX2, alkaline phosphatase (ALP), collagen Ι, OCN and Smad1 were significantly increased via miR-144-5p inhibition, but the opposing effects on the above mRNAs and proteins were dBMDM‐derived exosomal miR‐144‐5p suppresses the bone repair and regeneration in vitro and vivo After transfecting the miR-144-5p-inhibitor or inhibitor-NC into BMSCs which were co-cultured with dBMDM-exos, the expression of miR-144-5p were significantly decreased in miR-144-5p-inhibitor group, but significantly increased osteogenic related genes, Smad1 and the mineralization were detected when compared with inhibitor-NC group (Fig. 8a–f )

Summary

Introduction

Patients with diabetes have an increased risk of nonunion and delayed union of fractures. BMDMs have been shown to be in adverse pathological status caused via DM, and secrete osteogenesis-impeded factors including IL-1, TNF-α, iNOS and so on, impairing osteogenic differentiation and increasing the probabilities of an uncontrolled regulation of fracture repair [14,15,16,17,18,19]. These factors, neither entirely represent the macrophages-BMSCs crosstalk under diabetic disorder nor completely account for the mechanisms underlying the impaired bone repair and regeneration under diabetic condition in DM

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