RESUMO
Haematopoietic system represents the main source of haematopoietic stem cells and probably of multipotential adult progenitor cells and mesenchimal stem cells at first described as colony forming unit-fibroblast. Whereas there are many studies on the gene expression profile of the different precursors along their haematopoietic differentiation, few data (sometimes conflicting) have been reported about the phenotype of the cells (present in bone marrow and possibly in cord blood) able to differentiate into non-haematopoietic cells. As both postnatal bone marrow and umbilical cord blood contain nestin positive cells able to proliferate and differentiate into the main neural phenotype (neuron, astroglia and oligodendroglia) many authors considered nestin a neuroepithelial precursor marker that seems to be essential also in multipotential progenitor cells of pancreas present both in rat and in human pancreatic islets (called nestin positive islet derived progenitors). Although the importance of nestin in these cells appears to be evident, it remains yet to clarify the number and the sequential expression of the genes coding all the transcription factors essential for beta cells differentiation and therefore the conditions able to induce the expression of many important transcription factors genes such as isl-1, pax-4, pdx-1 and ngn-3. Among them pdx-1 is a gene essential for pancreas development which is able to control ngn-3 in activating the expression of other differentiation factors for endocrine cells. Here, we describe for the first time in human umbilical cord blood cells (UCB) the pattern of expression of a panel of markers (nestin, CK-8, CK-18) and transcription factors (Isl-1, Pdx-1, Pax-4, Ngn-3) considered important for beta cells differentiation. Our data demonstrate that UCB contains a cell population having a phenotype very similar to endocrine cell precursors in transition to beta cells.