1. ¹Laboratory of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan
2. ²Department of Orthopedic Surgery, Huashan Hospital, Fudan University, Shanghai, China

Abstract

It has been shown that the stromal cell population found in bone marrow can be expanded and differentiated into cells with the phenotypes of bone, cartilage, muscle, neural and fat cells. However, whether or not mesenchymal stem cells (MSC) are present in human umbilical cord blood (UCB) has been the subject of ongoing debate. In this study, we report on a population of fibroblast-like cells derived from the mononuclear fraction of human UCB with osteogenic and adipogenic potential, and the presence of a subset of cells that have been maintained in continuous culture for more than six months. These cells were found to express CD29, CD44, CD90, CD95, CD105, CD166 and major histocompatibility antigen complex (MHC) class I, but not CD14, CD34, CD40, CD45, CD80, CD86, CD117, CD152 and MHC class II.

We also compared the gene expression after gene transfer using lenti- and adenoviral vectors carrying the green fluorescence protein (GFP) to the MSC derived from UCB since a reliable gene delivery system is required to transfer target genes into MSC which have attracted attention as potential platforms for the systemic delivery of therapeutic genes. The lentiviral vectors can transduce these cells more efficiently than adenoviral vectors, and transgene expression was maintained for at least five weeks. These results demonstrated that human UCB is a source of mesenchymal progenitors and may be utilized in cell transplantation and a wide range of gene therapy treatments.