Authors: Koji Tomiyama, Noriko Murase, Donna Beer Stolz, Hideyoshi Toyokawa, Daniel R. O’Donnell, Darren M. Smith, Jason R. Dudas, J. Peter Rubin and Kacey G. Marra

Title: Characterization of Transplanted Green Fluorescent Protein+ Bone Marrow Cells into Adipose Tissue

Summary: Following transplantation of green fluorescent protein (GFP)-labeled bone marrow (BM) into irradiated, wild-type Sprague-Dawley rats, propagated GFP_ cells migrate to adipose tissue compartments. To determine the relationship between GFP_ BM-derived cells and tissue-resident GFP_cells on the stem cell population of adipose tissue, we conducted detailed immunohistochemical analysis of chimeric whole fat compartments and subsequently isolated and characterized adipose-derived stem cells (ASCs) from GFP_BM chimeras. In immunohistochemistry, a large fraction of GFP_ cells in adipose tissue were strongly positive for CD45 and smooth muscle actin and were evenly scattered around the adipocytes and blood vessels, whereas all CD45_ cells within the blood vessels were GFP_. A small fraction of GFP_ cells with the mesenchymal marker CD90 also existed in the perivascular area. Flow cytometric and immunocytochemical analyses showed that cultured ASCs were CD45_/CD90_/CD29_. There was a significant difference in both the cell number and phenotype of the GFP_ ASCs in two different adipose compartments, the omental (abdominal) and the inguinal (subcutaneous) fat pads; a significantly higher number of GFP_/CD90_ cells were isolated from the subcutaneous depot as compared with the abdominal depot. The in vitro adipogenic differentiation of the ASCs was achieved; however, all cells that had differentiated were GFP. Based on phenotypical analysis, GFP_ cells in adipose tissue in this rat model appear to be of both hematopoietic and mesenchymal origin; however, infrequent isolation of GFP_ ASCs and their lack of adipogenic differentiation suggest that the contribution of BM to ASC generation might be minor.

Source: Stem Cells 2008;26;330-338; originally published online Nov 1, 2007; DOI: 10.1634/stemcells. 2007-0567