Article

Adipose tissue engineering in three-dimensional levitation tissue culture system based on magnetic nanoparticles.

University of Texas Health Science Center at Houston, Institute of Molecular Medicine , 1825 Pressler st., Rm. 630-G, Houston, Texas, United States, 77030, 713-500-3146
Tissue Engineering Part C Methods (Impact Factor: 4.64). 09/2012; DOI: 10.1089/ten.TEC.2012.0198
Source: PubMed

ABSTRACT White adipose tissue (WAT) is becoming widely used in regenerative medicine / cell therapy applications, and its physiological and pathological importance is increasingly appreciated. WAT is a complex organ composed of differentiated adipocytes, stromal mesenchymal progenitors known as adipose stem cells (ASC), as well as endothelial vascular cells and infiltrating leukocytes. Two-dimensional (2D) culture that has been typically used for studying adipose cells does not adequately recapitulate WAT complexity. Improved methods for reconstruction of functional WAT ex vivo are instrumental for understanding of physiological interactions between the composing cell populations. Here, we used a three-dimensional (3D) tissue culture system based on magnetic nanoparticle levitation to model WAT development and growth in organoids termed "adipospheres". We show that 3T3-L1 preadipocytes remain viable in spheroids for a long period of time, while in 2D culture they lose adherence and die upon reaching confluence. Upon adipogenesis induction in 3T3-L1 adipospheres, cells efficiently formed large lipid droplets typical of white adipocytes in vivo, while only smaller lipid droplet formation is achievable in 2D. Adiposphere-based co-culture of 3T3-L1 preadipocytes with murine endothelial bEND.3 cells led to vascular network assembly concomitantly with lipogenesis in perivascular cells. Adipocyte-depleted stromal-vascular fraction (SVF) of mouse WAT cultured in 3D resulted in formation of organoids with vasculature containing luminal endothelial and perivascular stromal cells layers. Adipospheres made from primary WAT cells displayed robust proliferation and complex hierarchical organization reflected by a matricellular gradient incorporating ASC, endothelial cells and leukocytes, while ASC quickly outgrew other cell types in adherent culture. Upon adipogenesis induction, adipospheres derived from the SVF displayed more efficient lipid droplet accumulation than 2D cultures indicating that 3D intercellular signaling better recapitulates WAT organogenesis. Combined, our studies show that adipospheres are appropriate for WAT modeling ex vivo and provide a new platform for functional screens to identify molecules bioactive toward individual adipose cell populations. This 3D methodology could be adopted for WAT transplantation applications and aid approaches to WAT-based cell therapy.

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