Karyotypic Evaluation of Expanded Rat MAPCs.

Summary

The clinical utility of an ex-vivo expanded stem cell population is dependent on both safety and efficacy. As an initial step toward ensuring that expanded adult stem cell populations are safe, we harvested bone marrows from four different strains of rat and cultured mononuclear cells under low serum media shown previously to allow for propagation of Multipotent Adult Progenitor Cells (MAPCs). We then determined the karyotype and tri-lineage potential for these expanding populations at numerous population doublings. We observe that an average of 6.7% of cells within these cultures are tetraploid and 2.7% of cells show other karyotypic alterations. In spite of this low level of karyotypic instability, no persistent chromosomal abnormalities are present in these cultures after more than 100 population doublings. As measured by qPCR and indirect immunofluoroescence for lineage specific marker genes, these cells have tri-lineage potential and are therefore considered to be MAPCs. These data support and extend previous conclusions that MAPC cultures with a nearly normal karyotype can be routinely established and expanded from rat bone marrow providing important standards for performance and safety in pre-clinical disease models.