Human adipose tissue-derived mesenchymal stem cells (hASCs) are useful for regeneration of inflamed or injured tissues. To identify secreted hASC proteins during inflammation, hASCs were exposed to tumor necrosis factor-alpha (TNF-alpha) and conditioned media derived from hASCs were analyzed by liquid chromatography coupled with tandem mass spectrometry. We identified 187 individual proteins as secreted proteins (secretome) in hASC-conditioned media; 118 proteins were secreted at higher levels upon TNF-alpha treatment. The TNF-alpha-induced secretome included a variety of cytokines and chemokines such as interleukin-6 (IL-6), IL-8, chemokine (C-X-C motif) ligand 6, and monocyte chemotactic protein-1 (MCP-1). TNF-alpha also increased expression of various proteases including cathepsin L, matrix metalloproteases and protease inhibitors, and induced secretion of long pentraxin 3, a key inflammatory mediator implicated in innate immunity. TNF-alpha-conditioned media stimulated migration of human monocytes, which play a key role in inflammatory responses. This migration was abrogated by pretreatment with neutralizing anti-IL-6, anti-IL-8, and anti-MCP-1 antibodies, suggesting that IL-6, IL-8, and MCP-1 are involved in migration of monocytes. Taken together, these results suggest that TNF-alpha-induced secretome may play a pivotal role in inflammatory responses and that shotgun proteomic analysis will be useful for elucidation of the paracrine functions of mesenchymal stem cells.

Inorganic nanocrystals have attracted much attention for therapeutic and diagnostic applications due to their unique optical, magnetic, and fluorescent properties.[1] Among these various nanocrystals, colloidal superparamagnetic iron oxide (e.g., γ-Fe 2 O 3 and Fe 3 O 4 ) have been extensively highlighted for many biomedical applications such as contrast agents for magnetic-resonance (MR) imaging, therapeutic gene carriers, protein purification, and sensors for nucleic-acid and virus detection. [2] In principle, it is of utmost importance to prepare highly stable magnetic nanocrystals in aqueous solutions to maximize in vivo half-life and tissuespecificity. However, the fabrication of such stable, bioactive magnetic nanocolloids has proven to be nontrivial.Methods for hydrophilic surface modification include addition of surface-active small molecules or polymeric stabilizers [3] and synthesis of magneto-composites via encapsulation.