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isolation reports in the literature, protocols for the isolation of cells from these
tissues and in particular from adipose tissue are the subject of much debate.
Bridging the gap between the surgical, scientifi c, therapeutic, and technical fi elds
requires standardized protocols to be established for adipose-derived stromal/stem
cell (ASC) processing and should address preharvesting requirements, the process
of tissue harvesting (volumes and sites), isolation and expansion methods, as well
as post expansion manipulation in order to achieve successful transplantation.
10.2 Factors Infl uencing ASC Characteristics
10.2.1 Adipose Tissue Type and Anatomical Location
Three types of adipose tissue are found: (1) white adipose (WAT) tissue , (2) brown
adipose tissue (BAT) , and (3) beige or brite adipose tissue. Adipose tissue can fur-
ther be classifi ed according to macroscopic tissue type, anatomical location, and
structural/functional characteristics.
Although both WAT and BAT are of mesodermal origin, they are believed to
originate from different mesenchymal stem cell lineages. Brown adipose tissue,
anatomically located around the major organs in a neonate and known to dissipate
with age, contains large numbers of intracellular mitochondria that release heat via
oxidation of fatty acids mediated by BAT-specifi c uncoupling protein-1 (UCP1).
Classical BAT derived from a myf-5 (myogenic marker)-positive cellular lineage is
specialized to dissipate chemical energy serving a protective function against hypo-
thermia (Giralt and Villarroya 2013 ; Wu et al. 2012 ).
Emerging from a myf-5-negative cellular lineage and developing in multiple
anatomical sites, WAT stores chemical energy and demonstrates known structural,
functional, metabolic, and endocrine differences between different WAT deposits
(Gimble et al. 2007 ; Giralt and Villarroya 2013 ; Sbarbati et al. 2010 ; Wu et al.
2012 ).
Beige or brite adipose tissue has morphological and molecular characteristics of
classical thermogenic brown adipocytes by responding to cyclic AMP stimulation
with high UCP1 expression and respiration rates. Although beige adipose tissue
emerges in WAT from a myf-5-negative cellular lineage and has low basal expres-
sion of UCP1, beige adipose cells demonstrate a distinct pattern of gene expression
(Giralt and Villarroya 2013 ; Wu et al. 2012 ). It was demonstrated that peroxisome
proliferator-activated receptor gamma (PPAR-γ) ligands require full agonism to
induce a beige/brite adipocyte gene program in WAT, by activating the co-regulator
PRDM16 and B cell factor-2, recruiting PPAR-γ to BAT-selective genes (Giralt and
Villarroya 2013 ; Ohno et al. 2012 ).
Macroscopically distinct WAT can further be classifi ed according to functional-
ity and anatomical location, which include (1) bone marrow, (2) mammary, and (3)
mechanical (Gimble et al. 2007 ). Bone marrow adipose tissue passively occupies
space no longer required for hematopoiesis and actively serves as an energy reservoir
F.A. van Vollenstee et al.