Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Adipose stem cells and solid organ transplantation Sunil S. Tholpady, Roy C. Ogle and Adam J. Katz Introduction The present review will cover the basic research per- formed with adipose stem cells (ASCs) over the past several years as well as pertinent translational research. The properties of ASCs that make them particularly interesting to the transplant surgeon will then be covered. These properties include regeneration of native tissue, support of microvasculature, and immunomodulation. These properties will undoubtedly expand the current usage of these cells. The term ‘stem cell’ has been employed extensively in multiple media outlets and subsequently has a definition that dependently differs by the source. To some, it refers to cells derived from the embryonic stages of human development, known as embryonic stem cells. The use of these cells is laden with political and moral dilemmas that have hampered their full use. Cells derived from later fetal development also show promise for medical applications, but their research is embedded in an ethical quagmire. Because of these limitations, several divergent areas of investigation have uncovered a novel small mesenchymal cell that resides in several niches, including bone marrow, muscle, bone, fat, skin, and very likely many other tissues. These cells in vitro have the capacity to differ- entiate into other cell types when influenced by the extracellular milieu. The focus of this article is the ASC, which is derived from a mesodermally derived tissue, adipose [1]. However, under certain culture conditions and/or in-vivo environ- ments, these cells are capable of developing varying degrees of lineage characteristics suggestive of nerve, bone, cartilage, liver and more, indicating that they are not developmentally bound to mesodermal lineages only. Interestingly, several of the differentiative protocols are offshoots of studies performed several decades ago on immortalized model cell lines and bone marrow stromal cell lines [2]. These cells were shown to be able to differentiate into adipocytes [3], myocytes [4], osteoblasts, and neurons [5]. The serendipitous merging of knowledge gleaned from these previous studies, along with the intuition that stromal cells derived from subcutaneous adipose tissue were similar to those derived from bone marrow led to the discovery of ASCs. Isolated cells from fat appeared and behaved in a manner similar to immortalized cell lines Department of Plastic and Reconstructive Surgery, University of Virginia, Health Sciences Center, Charlottesville, Virginia, USA Correspondence to Adam J. Katz, MD, FACS, Associate Professor, Department of Plastic Surgery, Director, Laboratory of Applied Developmental Plasticity, University of Virginia, Charlottesville, VA, USA Tel: +1 434 924 5088; fax: +1 434 924 1333; e-mail: ajk2f@virginia.edu Current Opinion in Organ Transplantation 2009, 14:51–55 Purpose of review This review will cover the basic research performed with adipose stem cells (ASCs) over the past several years as well as pertinent translational research. The properties of ASCs that make them particularly interesting to the transplant surgeon will then be covered. These properties include regeneration of native tissue, support of microvasculature, and immunomodulation. These properties will undoubtedly expand the future utility of these cells. Recent findings Recent literature demonstrates that ASCs are able to differentiate into phenotypes resembling hepatic and pancreatic lineages. In addition, several groups have shown that ASCs possess immunomodulatory properties similar to bone marrow-derived mesenchymal stem cells. Several clinical case reports also suggest that ASCs are an effective treatment option for graft-versus-host disease. Summary Due to their ability to differentiate into pertinent target lineages, their ability to enhance angiogenesis, and their ability to impact immunologic responses, ASCs may prove clinically useful for the transplant surgeon. Keywords adipose stem/stromal cells, adipose tissue, differentiation, immune response Curr Opin Organ Transplant 14:51–55 ß 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins 1087-2418 1087-2418 ß 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI:10.1097/MOT.0b013e328320d2cf