Enzymatically labeled chromosomal probes for in situ identification of human cells in xenogeneic transplant models

Analysis of the viability, differentiation, clonogenicity and function of human stem/progenitor cells requires suitable xenograft models. However, the identification of transplanted cells has been generally difficult. Fluorescence in situ hybridization is a tedious method for analyzing tissues, and localization of transplanted cells with X or Y chromosome probes is limited by the sparse signals produced. Therefore, we examined the possibility of generating either pan-nuclear signals with a total human DNA probe or multiple nuclear signals with a pan-centromeric human DNA probe. The probes were labeled with digoxigenin to make reaction products visible by light microscopy and to allow the use of immunohistochemistry methods incorporating various color schemes to demonstrate specific properties of transplanted cells. The ability to localize all types of nucleated human cells with such probes will facilitate studies of stem cell biology and cell and gene therapy, as well as the development of new animal models.