HUMAN PERIPHERAL BLOOD STEM CELLS FROM THREE CULTURING TERMS POPULATIONS 59 Malays. Appl. Biol. (2013) 42(2): 59–63 * To whom correspondence should be addressed. PROLIFERATION RATE AND CELL SIZE ANALYSES OF HUMAN PERIPHERAL BLOOD SUSPENSION STEM CELLS FROM THREE CULTURING TERMS POPULATIONS MUNIANDY, M.K.R. 1 , RUZANNA, A.K. 1 , INTAN ZARINA, Z.A. 1* , ROHAYA, M.A.W. 2 , SAHIDAN, S. 1 , MAJLIS, B.Y. 3 and SHAHRUL HISHAM, Z.A. 1 1 School of Biosciences and Biotechnology, Faculty of Science & Technology, UKM, 43600 Bangi, Selangor, Malaysia. 2 Department of Orthodontic, Faculty of Dentistry, UKM, 50300 Kuala Lumpur, Malaysia. 3 Institute of Microengineering and Nanoelectronics,UKM, 43600 Bangi, Selangor, Malaysia. * E-mail: izzarina7@gmail.com ABSTRACT Stem cells that made up of embryonic stem cells and adult stem cells are well known for their ability to self renew and differentiate into matured cells. Adult stem cells isolated from peripheral blood system were used as the study sample. The objective of this study was to determine the relationship between size and proliferation potential of stem cells from 3 different culturing terms, i.e., short (7 days), medium (14 days), and long (30 days) terms. Density gradient centrifugation was applied in isolating mononucleated cells (MNCs) from peripheral blood sample. Isolated MNCs were washed with Hank’s Balanced Salt Solution and Phosphate Buffer Saline. The MNCs which cultured in complete media were then subjected to proliferation analysis every day for a time period of 30 days. RT-PCR analyses and cell size measurements were carried out at day 7, 14, and 30. Activation of KIT and SLAMF1 marker genes during RT-PCR analyses indicated that the isolated MNCs were stem cells. Analyses of proliferation rate and cell size showed that short term stem cells have the largest cell size with the lowest proliferation potential. While, medium term stem cells gave rise to a smaller stem cell population with higher proliferation potential compared to short term stem cells. Long term stem cells have smallest cell size with highest proliferation potential. In conclusion, each culturing term cell population had their own sizes and can be isolated based on those sizes. Key words: Stem cells, Proliferation Potential, RT-PCR INTRODUCTION Higher immunocompatibility with lower Graft- versus-host disease (GVHD) risk and lower chance of cancer formation as compared to embryonic stem cells make adult stem cells as a promising therapeutic and treatment candidate as well as a potential research subject (Leeb et al., 2011). An effective adult stem cells isolation method would provide a better chance to study the stem cells efficiently. Size of stem cells should be taken into consideration in peripheral blood stem cell isolation procedure since it may enrich the isolation product when combined with other technologies such as nanotechnology. Previous studies showed distinguishably larger hematopoietic stem cell (HSC) sizes can be applied in fabricating microfluidic devices that worked on bone marrow sample to isolate HSC and the result shows up to 98% enrichment (Schirhagl et al., 2011). Peripheral blood suspension stem cells used in this research were adult stem cells with multi- potential ability (Ruzanna et al., 2011). Adult stem cells are a part of developmental continuum in tissues such as blood since the cells yet to differentiate and co-exist with the differentiated mature cells in those tissues. Besides, adult stem cells are defined by their capacity for unlimited self renewal during the lifetime of the organism and multi-potential differentiation ability to differentiate into several lineages through symmetrical and asymmetrical division (Hall et al., 1989; Daniella et al., 2012). Peripheral blood is a potential stem cell source since the isolation method is non- invasive and the source is easily available compared to bone marrow. Previous studies proved that MNCs isolated from peripheral blood consist of adult stem cells, i.e., hematopoietic stem cells and mesenchymal stem cells (Yazid et al., 2011).