Objectives: Multipotent mesenchymal stem cells (MSc) have been known for a long period of time. These cells are adherent, clonogenic and fibroblastic and can be isolated from bone marrow stroma of postnatal organisms. Under appropriate conditions, these cells can give rise to broad spectrum of fully differentiated connective tissues including cartilage, bone, adipose tissues and muscle cells. Upon the isolation of cells in vitro, these cells tend to differentiate and it is very difficult to direct these cells into self-renewal in order to get more Multipotent MSc for medical purposes. In this study, the effect of leukemia inhibitory factor (LIF) on MSc has been investigated. In the presence of LIF, embryonic stem cells proliferate without differentiation. However the effect of LIF on MSc has not been fully investigated. Methods: Bone marrow stroma cells were extracted from 2-month-old and 8-month-old mice. These cells were cultured in a medium containing LIF. After formation of colonies, cells were stained by methyl en blue. The activity of alkaline Phosphatase was also investigated. To study the effect of LIF on self-renewal ability of MSc, cells were cultured in a primary culture containing LIF. Colonies formed in the primary cultures, were harvested and recultured. The number and size of colonies compared with these cultured without LIF. Results: In the presence of LIF, cells tend to express alkaline phosphates enzyme more than control cells. However, in the presence of LIF in primary culture, there was no difference in the number of colonies. The size and number of colonies in secondary culture were significantly increased among those cells grown in the presence of LIF in primary culture. The number and quality of colonies did not show any significant difference among those cells extracted from 2-month-old and 8-month-old mice. Conclusion: The presence of LIF in primary culture does not affect the number of colonies formed. However, most of the cells in the primary culture express alkaline phosphatase. These cells tend to differentiate into bones. The presence of LIF in primary culture increases the self renewal ability of cells. Also these cells have more proliferation ability in comparison with control cells. The numbers of mesenchymal stem cells with aging do not decrease. Therefore, mesenchymal stem cells do not age and their number stays constant during the lifetime.

Dear Editor-in-Chief: Infertility is one of the major increasing gynecological problems worldwide. The incidence of infertility varies between populations mainly due their dietary, lifestyle, environmental and occupational factors, and infectious diseases.

Introduction and Objective: Recent studies have demonstrated that mammalian preimplantation embryos are exposed to a mixture of many different growth factors and cytokines, expressed by the follicles, oviducts and endometrium. Receptors for many of these growth factors have also been shown to be expressed by preimplantation embryos. In vitro culture of human and animal's embryos in conventional media lacking growth factors can result in suboptimal growth and a variety of short-term and long-term developmental abnormalities. One of these factors is Leukemia Inhibitory Factor (LIF). The aim of this study was to evaluate the effects of LIF on the mouse preimplantation embryo development.Materials & Methods: Six to eight weeks old NMRI mice were superovulated by injection of 10IU PMSG and 10IU HCG 48h later. The mated mice were killed 48 hours after HCG injection, oviducts were flushed and two-cell embryos were collected and divided randomly to two groups (control and treatment). Control medium was HTF and treatment medium was HTF+1000u/ml LIF. In each group the embryos were cultured in an incubator at 37oC with 5% CO2 for 72h.The state of embryo development was evaluated in 12 hours interval using inverted microscope. Results: There was not any significant difference in the rate of morolla and blastocyst formation after 36 hours. In comparing hatching rates, 60 and 72 hours after culture, there were significant difference between control and treatment groups (p<0.008). Conclusion: LIF doesn’t provide obvious stimulation in the early mouse embryo development until morolla stage. However, it has positive effects on preimplantation blastocyst growth, differentiation and hatching.