201and cytokine source for osteogenic and hematopoietic events. During lactation,
energy and some nutrients are provided by mammary adipose tissue, regulated in
part by pregnancy-associated hormones (Gimble et al. 2007 ). It was suggested by
Hamosh and colleagues that lipoprotein lipase activity from mammary adipose tis-
sue diverts dietary lipid from storage in adipose tissue to mammary gland for milk
formation (Hamosh et al. 1970 ). Mechanical adipose tissue offers support to critical
structures in the body such as the retro-orbital fat pads, which provide support to the
eye (Gimble et al. 2007 ).
Structural and anatomical location also play a role in WAT classifi cation. Deposit
WAT can be found in the periumbilical area, demonstrating tightly packed cells with
weak isolated collagen fi bers and few blood vessels. Structural WAT located in the
iliac and femoral areas demonstrates well-represented stroma and good vasculariza-
tion. Fibrous WAT occurs in areas experiencing great mechanical stress, as evi-
denced by the individual fi brous shell of every adipocyte (Sbarbati et al. 2010 ).
Over the past decade, it has become clear that adipose tissue must be regarded as
a complex organ with metabolic functions that extend beyond the classical role of
thermoregulation and storage of free fatty acids (FFA ) after food intake, as well as
the release of FFA during periods of fasting to ensure a suffi cient and constant
source of energy (Hajer et al. 2008 ; Harwood 2012 ). Recent studies have described
adipose tissue as a metabolic and endocrine organ producing various substances
including adipocyte-derived hormones such as leptin and adipsin; bioactive peptides
known as adipokines such as adiponectin, visfatin, omentin, and resistin to name a
few; as well as cortisol and various sex and steroid hormones. These substances act
both locally (paracrine/autocrine) and systemically (endocrine), exerting various
physiological effects (Gimble et al. 2007 ; Harwood 2012 ; Kershaw and Flier 2004 ).
It is well established that adipose tissue plays a critical role in the maintenance
of energy homeostasis through secretion of a large number of adipokines that inter-
act with peripheral and central organs such as the brain, vasculature, liver, pancreas,
and skeletal muscle to control diverse processes. These processes include feeding
behavior, blood coagulation, carbohydrate metabolism, lipid metabolism, infl am-
mation, and energy expenditure (Chu et al. 2001 ; Ran et al. 2006 ; Yamauchi et al.
2001 ). It has also been demonstrated in humans that the anatomical location of
adipose tissue has an impact on metabolic function. Visceral adipocytes have been
shown to be more resistant to the antilipolytic effects of insulin and are more sensi-
tive to the stimulation of lipolysis by catecholamines when compared to subcutane-
ous adipocytes (Bjorntorp 2000 ).
Prunet-Marcassus and co-workers ( 2006 ) demonstrated the complex nature of
adipose tissue by showing different antigenic features and differentiation potentials
in subcutaneous versus internal WAT and BAT in a murine model and also different
ASC subsets depending on the anatomical location of the fat pads. BAT displayed a
reduced plasticity and fewer ASC numbers when compared to WAT. Furthermore,
subcutaneous and internal/deep WAT demonstrated discrete differences in the phe-
notype of their cell populations (Prunet-Marcassus et al. 2006 ). This raises the
question as to whether the anatomical location of WAT could affect the functional
capabilities of ASCs.
10 Harvesting and Collection of Adipose Tissue for the Isolation...