Mesenchymal stromal cells (MSCs) are multipotent, self-renewing progenitor cells that can differentiate into adipocytes, chondrocytes, and osteocytes (1). Cultured MSCs are plastic-adherent and spindle-shaped, and they express cell-surface markers CD44, CD73, CD90, and CD105, but not CD14, CD34, CD45, CD11b, CD79a, CD19, or HLA-DR (2, 3). First isolated from bone marrow (BM), human MSCs have been investigated extensively in clinical studies. MSCs also have been isolated from adipose tissue (4) and peripheral blood (5). Perinatal organs and tissues such as…