20310.2.2 Patient Age and Gender
Marked differences have been observed between genders in both the metabolism
and endocrine function of adipose tissue. Women are known to have a higher per-
centage of body fat and mainly store adipose tissue in the gluteal-femoral region.
Adiposity in this region is associated with larger fat cell size with increased stimu-
lated lipolysis and triglyceride synthesis. Adipose tissue storage in men is primarily
in the visceral and abdominal regions. Obesity in men is associated with increased
lipoprotein lipase activity and with decreased stimulated lipolysis and triglycerides
synthesis (Blaak 2001 ; Edens et al. 1993 ; Fried et al. 1993 ). Several studies have
shown that the differences in visceral adipocyte metabolism between genders disap-
pear with menopause. It was further suggested that the female sex hormones may
play a role in this gender-specifi c adipose deposition; this includes, for example,
weight gain in the abdominal region of postmenopausal women as well as associ-
ated metabolic changes (Rebuffe-Scrive et al. 1989 ; Trujillo and Scherer 2006 ).
Age and gender are also important factors to consider when isolating MSCs from
adipose tissue. In the publication by Schipper and colleagues ( 2008 ), the authors
stratifi ed their study into different ages and compared the characteristics of ASCs
isolated from the following age groups: 25–30, 40–45, and 55–60 years. The
younger patients demonstrated signifi cantly higher cell proliferation rates and
higher lipolysis activity, with increased PPAR-γ expression in all of the subcutane-
ous deposits compared to the other two groups. Interestingly, with the addition of
TZDs during adipogenic induction in vitro, the 40–45-year group showed statisti-
cally increased adipogenesis when compared to the other groups. When considering
the site of isolation, only the upper arm deposits maintained a high lipolytic activity,
regardless of the patient’s age, when compared to the other sites (medial thigh, tro-
chanteric, and both superfi cial and deep abdominal adipose deposits) (Schipper
et al. 2008 ). There is still controversy with regard to what causes aging of MSCs,
whether it is related to intrinsic or extrinsic factors, but in all likelihood, both. It was
suggested by Zhou et al. ( 2008 ) that intrinsic factors such as senescence-associated
β-galactosidase together with increased expression of p53 and its pathway genes
(p21 and BAX) may be responsible for mediating reduced proliferation in MSCs
from older patients by inducing senescence (Zhou et al. 2008 ). In contrast, extrinsic
factors such as a reduced synthesis of proteoglycans and glycosaminoglycans in the
microenvironment reduce cell proliferation and viability in vivo. In addition, the
accumulation of advanced glycosylated end products inhibits proliferation of MSCs
by activating apoptosis and reactive oxygen species production (Bi et al. 2005 ;
Kume et al. 2005 ). This clearly illustrates the variability of ASCs isolated from
patients from different age groups.
In contrast, no age-related or gender signifi cant differences in cell surface marker
expression (CD34, CD44, CD54, CD73, CD80, CD90, CD105, CD106, CD166,
and STRO-1) from MSCs isolated from synovial fat pads were observed (Fossett
et al. 2012 ). Also, the general trends observed with age-related decline in popula-
tion doublings at low seeding densities and age-related increase in population
10 Harvesting and Collection of Adipose Tissue for the Isolation...