Skeletal and Adipose Tissue Engineering with Adipose-Derived Stromal Cells

Abstract

There are wide ranges of pathologies leading to critical adipose and skeletal tissue loss including trauma, cancer resection and congenital anomalies. With half of the adult population in the United States estimated to be affected by a chronic disease according to the World Health Organization, the biomedical burden for replacement tissue continues to rise. By 2030, the number of adults over the age of 65 is expected to double to over 70 million in the United States (Institute of Medicine, 2008). The use of autologous tissue grafts and allografts for multiple organ systems have been successfully employed clinically, however many inherent disadvantages to these strategies exist including graft failure, infection, donor site morbidity etc. (Becker et al. 2011). While synthetic materials are not limited by availability, they are prone to infection, rejection, and breakdown over time (Keefe, 2009). Due to these inherent limitations, true regenerative medicine remains the ultimate goal for tissue replacement. In 2001, researchers isolated a new population of adult multipotent cells in lipoaspirate (Zuk, et al. 2001, 2002). Since the discovery of adipose-derived stromal cells, a tremendous amount of work has been done in characterizing this population of cells and defining their capacity for multipotent differentiation. Adipose-derived stromal cells have potential advantages over other types of stem cells such as mesenchymal stem cells in that they are widely available and easily harvested through a simple liposuction procedure without altering their viability. Adipose-derived stromal cells can differentiate into mesodermal cell lines and offer a broad range of possibilities for application within the field of tissue engineering. These cells have already been put through several clinical trials in the treatment of a diverse array of pathologies including ST-elevated myocardial infarctions, Crohn’s fistulas, and spinal cord injuries (Clinical Trials.gov, 2011). Bone regeneration is an area of great interest in the field of tissue engineering. Over sixty million Americans are expected to be diagnosed with osteoporosis or low bone mass by the year 2020 (Samelson & Hannon, 2006). This can generate critical pathology as 1 in 2 women and 1 in 4 men over the age of fifty experiences an osteoporotic fracture in their lifetime (National Osteoporosis Foundation, 2011). With limited availability of autologous bone grafts, a bioengineered tissue replacement would be an ideal clinical alternative. Adiposederived stromal cells were shown early on to have the capability for osteogenic