Targeting local lymphatics to ameliorate heterotopic ossification via FGFR3-BMPR1a pathway

Dali Zhang,Fangfang Li,Qiaoyan Tan,Shuo Huang,Zhenhong Ni,Han Qi ,Siru Zhou,Zuqiang Wang,Jing Yang,Junlan Huang,Nan Su,Meng Xu,Fei Luo ,Wanling Jiang,Ruobin Zhang,Di Chen,Jerry Q Feng,Hangang Chen,Yin Liang ,Ying Zhu,Mi Liu,Min Jin,Xiangjian Luo ,Xiaolan Du,Xianding Sun,Yangli Xie

doi:10.1038/s41467-021-24643-2

Abstract

Acquired heterotopic ossification (HO) is the extraskeletal bone formation after trauma. Various mesenchymal progenitors are reported to participate in ectopic bone formation. Here we induce acquired HO in mice by Achilles tenotomy and observe that conditional knockout (cKO) of fibroblast growth factor receptor 3 (FGFR3) in Col2+ cells promote acquired HO development. Lineage tracing studies reveal that Col2+ cells adopt fate of lymphatic endothelial cells (LECs) instead of chondrocytes or osteoblasts during HO development. FGFR3 cKO in Prox1+ LECs causes even more aggravated HO formation. We further demonstrate that FGFR3 deficiency in LECs leads to decreased local lymphatic formation in a BMPR1a-pSmad1/5-dependent manner, which exacerbates inflammatory levels in the repaired tendon. Local administration of FGF9 in Matrigel inhibits heterotopic bone formation, which is dependent on FGFR3 expression in LECs. Here we uncover Col2+ lineage cells as an origin of lymphatic endothelium, which regulates local inflammatory microenvironment after trauma and thus influences HO development via FGFR3-BMPR1a pathway. Activation of FGFR3 in LECs may be a therapeutic strategy to inhibit acquired HO formation via increasing local lymphangiogenesis.

Highlights

Acquired heterotopic ossification (HO) is the extraskeletal bone formation after trauma
X-ray and μCT analysis revealed enlarged heterotopic bone in the Achilles tendon of FGFR3Col[2] mice relative to that in FGFR3f/f controls at 4 weeks after tenotomy (Supplementary Fig. 1a)
hematoxylin and eosin (H&E) and Safranin O/ Fast Green (SOFG) staining revealed abundant cartilage in the repaired tendon of FGFR3Col[2] mice at 4 weeks after Achilles tenotomy, whereas few chondrocytes were observed in the tendon of control mice (Supplementary Fig. 1b-d)

Summary

Introduction

Acquired heterotopic ossification (HO) is the extraskeletal bone formation after trauma. Local administration of FGF9 in Matrigel inhibits heterotopic bone formation, which is dependent on FGFR3 expression in LECs. Here we uncover Col2+ lineage cells as an origin of lymphatic endothelium, which regulates local inflammatory microenvironment after trauma and influences HO development via FGFR3-BMPR1a pathway. Various osteogenic progenitors including fibroblasts[7], endothelial cells[8], and mesenchymal stem cells (MSCs) that are positive for Prx[19], Gli[110], and nestin[3] have been reported to participate in HO formation through diverse signaling pathways. Osteogenic signaling pathways such as BMP signaling play central roles in HO development.

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Results

Conclusion