Investigation Of The Pathogenisis Of Aplastic Anemia In Children By Detecting Expression Of Stem Cell Factor And Its Receptor

Backgroud and Objectives : Aplastic anemia (AA) is characterized by multilineage bone marrow failure resulting in pancytopenia. Although its actual cause remains unknown, possible mechanisms include a primary stem cell defect, immunemediated inhibition of haemopoiesis, or an abnormal bone marrow microenvironment. It has a high occurrence in children. Many experiments have exposed that bone marrow mononuclear cells (BMMNC ) of aplastic anemia consistently produced a significantly lower number of colonies than normal controls and had a defect in their function, but the fact that 50%-80% patients with aplastic anemia recovered from immunosuppressive therapy suggested that even in serious aplastic anemia (SAA), there were some hematopoietic stem cells left. With the fast development of the technology of cell and molecular biology and immunology, some investigators found that hematopoietic growth factors and theirs receptors play an important role in the mechanism of aplastic anemia. Among them, stem cell factor (SCF) and its receptor c-kit (CD 117) receive more and more attention. SCF is the ligand for the dimeric c-kit tyrosine kinase receptor. They act on primary hematopoietic stem cells and progenitor cells. There have been some reports about the mechanism of aplastic anemia by determining the expression of stem cell factor and its receptor, but they are all about adults. Up to now, there has been none about children. The present study investigated the expression of stem cell factor and its receptor in order to study the mechanism of aplastic anemia in children.Meterials and methods:The cases include 21 children with SAA, 35 children with CAA.Clinical data were collected prospectively.33 children with non-hematopoietic disease were selected as the normal controls. The expression of stem cell factor and its receptor were investigated by means of reverse-transcriptase polymerase chain reaction (RT-PCR). X~2 test was used to analyze the data. Ap value of less than 0.05 was considered to indicate significance.Results: (1) The expression rate of c-kit mRNA of children with aplastic anemia is 30.4% ,and that of normal controls was 39.4% (.P>0.05) ; there was no significant difference between them; (2) The expression rate of c-kit mRNA of children with aplastic anemia is not related to the age ,gender, clinical type of children with AA(P>0.05) ; (3) The expression rate of SCF mRNA of children with aplastic anemia is 21.4% ,and that of normal controls was 42.4% .The expression rate of SCF mRNA of children with aplastic anemia was significantly lower than that of normal controls (P<0.05) ; (4) The expression rate of SCF mRNA of children with aplastic anemia is not related to the age ,gender of children with AA,too(P>0.05) ; but the expression rate of SCF mRNA of children with aplastic anemia is related to the clinical type of children with AA, the expression rate of SCF mRNA of children with SAA was significantly lower than that of CAA (P<0.05) ;Conclusions: (1) The expression rate of SCF mRNA of children with aplastic anemia was significantly lower than that of controls. As suggested that in AA, abnormal expression of SCF was at the transcription level; (2) C-kit receptor shows no significant association with mechanisms of aplastic anemia in children, but its structure and function need our further investigations;(3) SAA and CAA are the same disease except that SAA is more serious than CAA; (4)SCF may be of therapeutic value in children with aplastic anemia.