materials Article Tryptophan and Kynurenine Enhances the Stemness and Osteogenic Differentiation of Bone Marrow-Derived Mesenchymal Stromal Cells In Vitro and In Vivo Hai Thanh Pham 1,2 , Mitsuaki Ono 3,*, Emilio Satoshi Hara 4,* , Ha Thi Thu Nguyen 1,2,3, Anh Tuan Dang 1,2,3, Hang Thuy Do 1,2,3, Taishi Komori 1, Ikue Tosa 1, Yuri Hazehara-Kunitomo 1,3, Yuya Yoshioka 1, Yasutaka Oida 1, Kentaro Akiyama 1 and Takuo Kuboki 1 1 Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan;
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[email protected] (T.K.) 2 Faculty of Dentistry, Hai Phong University of Medicine and Pharmacy, Haiphong 04211, Vietnam 3 Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan 4 Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan * Correspondence:
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[email protected] (E.S.H.); Tel.: +81-86-235-7127 (M.O.); +81-86-235-6667 (E.S.H.); Fax: +81-86-222-7768 (M.O.); +81-86-235-6669 (E.S.H.) Abstract: Aging tissues present a progressive decline in homeostasis and regenerative capacities, Citation: Pham, H.T.; Ono, M.; Hara, which has been associated with degenerative changes in tissue-specific stem cells and stem cell E.S.; Nguyen, H.T.T.; Dang, A.T.; Do, niches.