Precise immunomodulation of the M1 to M2 macrophage transition enhances mesenchymal stem cell osteogenesis and differs by sex

Bone & Joint Research

article

Karthik Nathan¹  Laura Y. Lu¹  Tzuhua Lin¹  Jukka Pajarinen¹  Eemeli Jämsen²  Jhih-Fong Huang¹  Monica Romero-Lopez¹  Masahiro Maruyama¹  Yusuke Kohno¹  Zhenyu Yao¹  Stuart B. Goodman¹ 

[1] Department of Orthopaedic Surgery, Stanford University;Department of Medicine, University of Helsinki, and Helsinki University Hospital;Department of Bioengineering, Stanford University

关键词: Macrophages;    Mesenchymal stem cells;    Coculture;    Osteogenesis;    Sex differences;   

DOI  :  10.1302/2046-3758.810.BJR-2018-0231.R2

学科分类：骨科学

来源: British Editorial Society Of Bone And Joint Surgery

【 摘 要 】

ObjectivesUp to 10% of fractures result in undesirable outcomes, for which female sex is a risk factor. Cellular sex differences have been implicated in these different healing processes. Better understanding of the mechanisms underlying bone healing and sex differences in this process is key to improved clinical outcomes. This study utilized a macrophage–mesenchymal stem cell (MSC) coculture system to determine: 1) the precise timing of proinflammatory (M1) to anti-inflammatory (M2) macrophage transition for optimal bone formation; and 2) how such immunomodulation was affected by male versus female cocultures.MethodsA primary murine macrophage-MSC coculture system was used to demonstrate the optimal transition time from M1 to M2 (polarized from M1 with interleukin (IL)-4) macrophages to maximize matrix mineralization in male and female MSCs. Outcome variables included Alizarin Red staining, alkaline phosphatase (ALP) activity, and osteocalcin protein secretion.ResultsWe found that 96 hours of M1 phenotype in male cocultures allowed for maximum matrix mineralization versus 72 hours in female cocultures. ALP activity and osteocalcin secretion were also enhanced with the addition of IL-4 later in male versus female groups. The sex of the cells had a statistically significant effect on the optimal IL-4 addition time to maximize osteogenesis.ConclusionThese results suggest that: 1) a 72- to 96-hour proinflammatory environment is critical for optimal matrix mineralization; and 2) there are immunological differences in this coculture environment due to sex. Optimizing immunomodulation during fracture healing may enhance and expedite the bone regeneration response. These findings provide insight into precise immunomodulation for enhanced bone healing that is sex-specific.

【 授权许可】

CC BY-NC