Use of “Adult Stem Cells" in Children: the Current Status and Future Potentials

Abstract

Human stem cells are known to have vast potentials in treating human diseases. However, there are different kinds of stem cells being studied or applied clinically. Some of them, such as embryonal stem cells which can be prepared by nuclear transfer technology, have the genuine multipotent differentiating capacity but unfortunately, are restricted by the ethical and legal boundary for clinical application. While adult stem cells, which include haematopoeitic stem cells (HSCs), mesenchymal stem cells (MSCs), neural stem cells etc., are not as versatile in their differentiating ability but they are widely accepted for clinical use. Among adult stem cells, HSCs are the most extensively used clinically. HSCs can be derived from bone marrow, cord blood or mobilizedmobilised peripheral blood. Previously, HSCs transplant are confined to the treatment of haematological illnesses such as leukaemia, marrow failure or thalassaemia. It can also serve as a marrow support after megadose chemotherapy in selected solid tumours treatment. In recent decade, HSCs have been successfully applied to a wide range of non-haematological inherited diseases including metabolic disorders, storage diseases, primary immunodeficiency, bone disease (i.e. osteopetrosis). In addition, chemotherapy + CD34 selected autologous HSCs can now be used for many forms of poor risk autoimmune diseases including scleroderma, multiple sclerosis, refractory SLE or JIA. The experience of our centre in applying HSCs to these diseases will be discussed. Recently, bone marrow derived MSCs emerged as another important adult stem cells that can be applied to a wide spectrum of clinical diseases. Since they can form bone, cartilage, muscle and even cross lineage barrier into neurons and hepatocytes, they are intensively studied for the bioengineering purpose of replacing damaged tissues such as degenerated disc/cartilage or infarcted heart muscle. In paediatric setting, they have been tried for the treatment of osteogenesis imperfecta. In addition to their differentiating potential, they also have a potent immunosuppressive effect and recently, MSCs have been used in treating refractory graft versus host disease in organ transplant setting. Our laboratory has been studying the biology of human marrow derived MSCs for the past few years and some of the MSCs’ unique biological properties will be discussed.