Stimulation of proliferation and osteoblastic differentiation of human adipose tissue-derived mesenchymal stem cells by fibroblast growth factor-2 and dexamethasone
Eui Kyun, Park1,2, Sun-Young, Lee2, Min Jung, Son2, Tae-Ho, Kim2, Gilson, Kang3, Youngsook, Son4, Sukyoung, Kim5, Woo-Kie, Min2,6, Hong-In, Shin1,2, and Shin-Yoon, Kim2,6
1Department of Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University; 2Skeletal Diseases Genome Research Center, Kyungpook National University Hospital; 3Department of Advanced Organic Materials Engineering, Chonbuk National University, Jeonju, Korea; 4Laboratory of Tissue Engineering, Korea Institute of Radiological and Medical Sciences, Seoul Korea; 5School of Materials Engineering, Yeungnam University, Gyeongsan, Korea; 6Department of Orthopedic Surgery, Kyungpook National University, Daegu, Korea.
Tissue engineering using mesenchymal stem cells (MSCs) combined with suitable biomaterials is a promising technology for treatment or regeneration of tissue defects. MSCs can be isolated from many tissues including bone marrow and adipose tissues. However, due to their low numbers in the tissue, ex vivo expansion of MSCs is essentially necessary. In the present study, we investigated how to efficiently expand human adipose tissue derived mesenchymal stem cells (ATSCs) and stimulate their osteoblastic differentiation.
We isolated ATSCs from 6 independent donors with informed consent. Characterization of isolated ATSCs with stem cell makers revealed that cells over 98 % were positive for CD29, CD44 and CD90, indicating high enrichment of ATSCs. To find a stimulatory condition for proliferation of ATSCs, we tested several growth factors and found that low concentration of fibroblast growth factor-2 (FGF-2) (1 ng/ml) and dexamethasone (Dex) (10 nM) significantly enhanced proliferation of ATSCs by 25 - 40 % compared to control. We next asked whether the expanded ATSCs retain multi-potency. The expanded ATSC with FGF-2 and Dex for 7 days were differentiated into either osteoblastic or adipogenic cells, indicating the preservation of multi-potency. To further examine the stimulatory mechanisms for proliferation of ATSCs by FGF-2 and Dex, chemical inhibitors for intracellular signaling molecules were tested. Interestingly, JNK (SP600125) and Src family kinase (SU6656) inhibitors substantially reduced FGF-2 and Dex-induced proliferation of ATSCs while p38 MAP kinase and MEK inhibitors had no significant effect.
Collectively, the current study reveals that FGF-2 and Dex stimulate the proliferation of ATSCs with maintenance of multi-potency, and suggest that this combination is useful for ex vivo expansion of ATSCs. The results with pharmacological inhibitors also suggest that JNK and Src pathway(s) are involved in the stimulation of proliferation and probably osteoblastic differentiation of ATSCs by FGF-2 and Dex.
Key words: fibroblast growth factor-2, dexamethasone, human adipose tissue-derived mesenchymal stem cells, JNK, and Src