Korean J. Chem. Eng., 24(6), 1058-1063 (2007) SHORT COMMUNICATION 1058 † To whom correspondence should be addressed. E-mail: jkpark@dongguk.edu Effect of essential and nonessential amino acid compositions on the in vitro behavior of human mesenchymal stem cells Kyung-Min Choi, Hee-Hoon Yoon,Young-Kwon Seo, Kye-Yong Song*, Soon-Yong Kwon**, Hwa-Sung Lee***, Yong Soon Park***, Young-Jin Kim**** and Jung-Keug Park † Department of Chemical and Biochemical Engineering, Dongguk University, Seoul 100-715, Korea *Department of Pathology, Chung-Ang University, Seoul 156-756, Korea **Department of Orthopedics, Catholic University, Seoul 150-713, Korea ***Department of Medical Information Engineering, Kwangju Health Collage, Kwangju 506-701, Korea ****Biomedical Research Institute, Lifecord. Ltd., Suwon 442-749, Korea (Received 23 March 2007 • accepted 25 April 2007) Abstract Mesenchymal stem cells (MSCs) from bone marrow appear to be an attractive tool for use in tissue engi- neering and cell-based therapies due to their multipotent capacity. The majority of studies on MSCs have been re- stricted to the roles of growth factors, cytokines, and hormones. Based on previous reports demonstrating the im- portant roles of amino acids, we sought to evaluate the effect of essential amino acids (EAs) and nonessential amino acids (NEAs) on the proliferation and differentiation of MSCs. The results showed that the EA/NEA compositions during culture could significantly modulate MSC proliferation and differentiation and, especially, that EAs served as a potent positive modulator in the proliferation of MSCs without causing a deficit in the differentiation capacity of the cells. These results will be very useful in the production of MSC-based cell therapy products for use in the field of tissue engineering and regenerative medicine. Key words: Amino Acid, Proliferation, Differentiation, Mesenchymal Stem Cell, Bone Marrow INTRODUCTION Mesenchymal stem cells (MSCs) can be derived from specific organs, such as the gut, lung, liver, and bone marrow. MSCs iso- lated from bone marrow have been shown to have multilineage po- tential and have been used experimentally in cell-based therapies. MSCs are capable of giving rise to multiple mesenchymal cell line- ages, such as fibroblasts, osteoblasts, chondrocytes, and adipocytes, under specific culture conditions. In contrast to other adult cells, such as ligament cells, chondrocytes, and osteoblasts, MSCs are not rejected and can be easily obtained after bone marrow aspira- tion and subsequent in vitro expansion. However, continued cul- ture of MSCs for tissue engineering applications requires proper stimulation to prevent premature cell aging, spreading and inactiv- ity with increasing passage number [1-8]. To support and enhance the in vitro growth and activity of MSCs, the cell culture medium may be supplemented with various proteins and factors to mimic the physiologic environment in which cells optimally proliferate and differentiate [9-13]. The metabolism of cells in an organized environment is closely related to the intercellular metabolic interaction between different kinds of cells. However, when cells are isolated from their original tissues and cultured in a culture dish, their nutritional requirements should, as a matter of course, change and vary among each indi- vidual cell [14-17]. In fact, the stimulatory effect of various nutri- ents, especially amino acids, upon the growth rate of cells in vitro has been extensively investigated. Tyihak and Szende found that D-lysine exerted a tumor-promoting effect on cells, while D-aspar- tic acid, L-glutamic acid, D-arginine and L-lysine inhibited tumor growth [18,19]. Eagle observed the requirement of glycine for the growth of monkey kidney cells in the primary culture [20]. McCoy reported that the addition of serine and especially glycine promoted cell growth. However, cysteine, glycine, and serine did not influ- ence the growth rate of human tumor cells at any of the concentra- tions tested [21]. In the case of mesenteric ischemia, the addition of glycine, a non- essential amino acid, induced the downregulation of pro-apoptotic bax and caspase-3, whereas anti-apoptotic bcl-2 was upregulated in the glycine-treated animals [22]. Tanaka et al., found that L-serine promoted neuronal survival and that L-serine and glycine upregu- lated the expression of the anti-apoptotic gene product Bcl-w, while reducing apoptosis [23]. It was reported elsewhere that various con- centration of vitamin supplementations of hybridoma cells culture medium induced the down-regulation of bal-2 expression and re- duced the rates of apoptosis [24]. Extensive studies on hamsters have also demonstrated that the inclusion of certain amino acids (asparagine, aspartate, glycine, histidine, serine, and taurine) in the culture medium stimulates the development of 1-cell embryos into the morula/blastocyst in vitro. In contrast, other amino acids (cys- teine, isoleucine, leucine, phenylalanine, threonine, and valine) are known to strongly inhibit development [25,26]. Recently, amino acids exogenously supplemented were shown to affect mammalian embryonic development, and their beneficial effects have been examined in embryos from mice, hamsters, and cattle [27-29]. However, most studies on MSCs have been restricted to growth factors, cytokines, and hormones. Based on previous reports dem-