PPARγ silencing enhances osteogenic differentiation of human adipose-derived mesenchymal stem cells.
Peroxisome proliferator-activated receptor gamma (PPARγ) is the master regulator of adipogenesis, and has been indicated as a potential therapeutic target to promote osteoblast differentiation. However, recent studies suggest that suppression of PPARγ inhibits adipogenesis, but does not promote osteogenic differentiation in human bone marrow-derived mesenchymal stem cells (hBMSCs). It was reasoned that the osteogenic effect of PPARγ suppression may be masked by the strong osteogenesis-inducing condition commonly used, resulting in a high degree of matrix mineralization in both control and experimental groups. This study investigates the role of PPARγ in the lineage commitment of human adipose-derived mesenchymal stem cells (hADSCs) by interfering with the function of PPARγ mRNA through small interfering RNAs (siRNAs) specific for PPARγ2. By applying an osteogenic induction condition less potent than that used conventionally, we found that PPARγ silencing led to retardation of adipogenesis and stimulated a higher level of matrix mineralization. The mRNA level of PPARγ decreased to 47% of control 2 days after treatment with 50 nmol/l PPARγ2 siRNA, while its protein expression was 60% of mock control. In the meantime, osteogenic marker genes, including bone morphogenic protein 2 (BMP2), runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and osteocalcin (OC), were up-regulated under PPARγ silencing. Our results suggest that transient suppression of PPARγ promotes the onset of osteogenesis, and may be considered a new strategy to stimulate bone formation in bone tissue engineering using hADSCs.
Orthopaedic Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Bioscience Technology, Chang Jung Christian University, Tainan, Taiwan.
Mon-Juan
MJ
Lee
Hui-Ting
HT
Chen
Mei-Ling
ML
Ho
Chung-Hwan
CH
Chen
Shu-Chun
SC
Chuang
Sung-Cheng
SC
Huang
Yin-Chih
YC
Fu
Gwo-Jaw
GJ
Wang
Lin
L
Kang
Je-Ken
JK
Chang
D050156:Adipogenesis / Q000235:genetics; D000273:Adipose Tissue / Q000166:cytology*; D002454:Cell Differentiation / Q000235:genetics*; D048430:Cell Shape / Q000235:genetics; D020868:Gene Silencing; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics*; D047495:PPAR gamma / Q000235:genetics*; D034741:RNA, Small Interfering / Q000378:metabolism
D047495:PPAR gamma; D034741:RNA, Small Interfering
Human adipose tissue-derived mesenchymal stem cells; adipogenesis; osteogenesis; peroxisome proliferator-activated receptor gamma; small interfering RNA