TGF‐β/Smad2 signalling regulates enchondral bone formation of Gli1 + periosteal cells during fracture healing
Author(s) -
Xia Chenjie,
Ge Qinwen,
Fang Liang,
Yu Huan,
Zou Zhen,
Zhang Peng,
Lv Shuaijie,
Tong Peijian,
Xiao Luwei,
Chen Di,
Wang Pinger,
Jin Hongting
Publication year - 2020
Publication title -
cell proliferation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.647
H-Index - 74
eISSN - 1365-2184
pISSN - 0960-7722
DOI - 10.1111/cpr.12904
Subject(s) - progenitor cell , periosteum , gli1 , bone healing , microbiology and biotechnology , chondrogenesis , anatomy , stem cell , medicine , hedgehog signaling pathway , biology , signal transduction
Abstract Objectives Most bone fracture heals through enchondral bone formation that relies on the involvement of periosteal progenitor cells. However, the identity of periosteal progenitor cells and the regulatory mechanism of their proliferation and differentiation remain unclear. The aim of this study was to investigate whether Gli1‐Cre ERT2 can identify a population of murine periosteal progenitor cells and the role of TGF‐β signalling in periosteal progenitor cells on fracture healing. Materials and methods Double heterozygous Gli1‐CreER T2 ;Rosa26‐tdTomato flox/wt mice were sacrificed at different time points for tracing the fate of Gli1 + cells in both intact and fracture bone. Gli1‐CreER T2 ‐mediated Tgfbr2 knockout ( Gli1‐CreER T2 ;Tgfbr2 flox/flox ) mice were subjected to fracture surgery. At 4, 7, 10, 14 and 21 days post‐surgery, tibia samples were harvested for tissue analyses including μCT, histology, real‐time PCR and immunofluorescence staining. Results Through cell lineage‐tracing experiments, we have revealed that Gli1‐Cre ER T2 can be used to identify a subpopulation of periosteal progenitor cells in vivo that persistently reside in periosteum and contribute to osteochondral elements during fracture repair. During the healing process, TGF‐β signalling is continually activated in the reparative Gli1 + periosteal cells. Conditional knockout of Tgfbr2 in these cells leads to a delayed and impaired enchondral bone formation, at least partially due to the reduced proliferation and chondrogenic and osteogenic differentiation of Gli1 + periosteal cells. Conclusions TGF‐β signalling plays an essential role on fracture repair via regulating enchondral bone formation process of Gli1 + periosteal cells.