Cell transplantation has immense potential as a therapy for inherited and degenerative diseases. Generating stem-cell-like donor populations that can develop into various different lineages but also maintain their proliferative capacity in culture has proven difficult, however. Paul Schiller and coworkers now unveil a human bone-marrow-derived cell type that might fit the bill: marrow-isolated adult multilineage inducibe (MIAMI) cells (see ). Starting with whole unfractionated bone marrow, they coculture adherent and non-adherent cells on a fibronectin substrate, using a specific combination of growth factors, vitamins, low oxygen tension and cell density to mimic the stem cell microenvironment. Their selection and expansion strategy yields cells that express embryonic stem (ES) cell markers such as Oct-4, as well as markers characteristic of mesodermal, endodermal and ectodermal lineages. These MIAMI cells have a greater potential for multilineage differentiation than cells previously isolated from marrow - they can differentiate into osteoblasts, adipocytes, pancreatic cells and neuronal cells. Moreover, in contrast to many previously described stem-cell-like populations, MIAMI cells continue to proliferate beyond 50 doublings, without any signs of senescence. They thus represent promising tools for cell transplantation to repair damaged, aged or diseased tissues.
