RESUMO
Intravenous injections of human hematopoietic stem cells (hHSCs) is routinely used in clinic and for modeling hematopoiesis in mice. However, unspecific dilution in vascular system and non-hematopoietic organs challenges engraftment efficiency. Although spleen is capable of extra medullar hematopoiesis, its ability to support human HSC transplantation has never been evaluated. We demonstrate that intra-splenic injection results in high and sustained engraftment of hHSCs into immune-deficient mice, with higher chimerisms than with intravenous or intra-femoral injections. Our results support that spleen microenvironment provides a niche for HSCs amplification and offers a new route for efficient HSC transplantation.
Assuntos
Sobrevivência de Enxerto/fisiologia , Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/citologia , Baço/citologia , Animais , Antígenos CD34/metabolismo , Feminino , Citometria de Fluxo/métodos , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Injeções , Luciferases/genética , Luciferases/metabolismo , Medições Luminescentes/métodos , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Baço/metabolismo , Quimeras de Transplante , Transplante HeterólogoRESUMO
OBJECTIVES: The first-passage adherent human bone marrow fibroblast-like cell population corresponds, in terms of phenotype and three-lineage differentiation capacity (assayed in bulk culture), to commonly termed "mesenchymal stem cells". Here we determine the proportion of high proliferative capacity multipotent cells present in this population in order to estimate the proportion of cells that can or cannot be considered as stem and progenitor cells. MATERIAL AND METHODS: The single-cell cultures were established starting from human bone marrow-derived first-passage fibroblast-like cells and the proliferating clones were either transferred to secondary cultures to evaluate their further clonogenicity, or split into three wells to assess differentiation into each of the three different lineages. RESULTS: The analysis of 197 single-cell cultures from three different bone marrow donors shows that onlyâ¼40% of so-called "mesenchymal stem cells" exhibit multipotency and are capable of sustained clonogenicity in secondary cultures. CONCLUSION: Even in the first ex vivo passage under favorable conditions the majority (â¼60%) of so-called "mesenchymal stem cells" are not multipotent and thus do not represent a stem cell entity.