Human mesenchymal stem cells

The identity of cells that establish the hematopoietic microenvironment (HME) in human bone marrow (BM), and of skeletal ("mesenchymal") stem cells (SSCs) found in BM stroma, have long remained elusive. We show that MCAM/CD146-expressing, subendothelial cells in human BM stroma are both the self-renewing SSCs and the cells that transfer the HME at heterotopic sites upon transplantation. Establishment and self-renewal of SSCs in developing BM in vivo occurs via specific, dynamic interactions with developing sinusoids. Non-differentiated SSCs residing on the sinusoidal wall, but not differentiated osteoblasts, express Angiopoietin-1 (a pivotal molecule of the HSC "niche" involved in vascular remodeling). Our data reveal the functional relationships between establishment of the HME in vivo, establishment of SSCs in BM sinusoids, and angiogenesis. Keywords: comparative genomics, genetic modification The series is composed by 7 samples hybridized to Affymetrix GeneChips. 4 of these samples (A18, A22, A23 e A27) are different clones of mesenchymal stem cells, while the other 3 represent different treatments of one of these clones with specific growth factors.