Page 4 - Sexual Health Treatments

Adipose-Derived Stem Cells and Erectile Dysfunction 323

Figure 2 Schematic for the mutilineage differentiation of adipose-derived stem cells and associated factors.

markers S100, nestin, and NF70[26]. Isobutyl- that reacts specifically with Y1136. This effect was
methylxanthine (IBMX), indomethacin (INDO), also abrogated by PPP. Thus, the IBMX-induced
and insulin were the active ingredients in a previ- neuron-like differentiation of ADSCs is mediated
ously established neural induction medium (NIM). by IGF signaling through the phosphorylation of
It was also found that IBMX alone was as effective IGF-IR at Y1136.
as NIM in the induction of morphological changes
as well as neuronal marker expression. The cellular SMC Differentiation
signaling pathways involved in this neuron differ- The smooth muscle is a major component of erec-
entiation were studied by treating ADSCs with tile tissues and essential for the normal erectile
IBMX in the presence or in the absence of each of function. The use of ADSCs for cell-based tissue
eight specific inhibitors of different signaling engineering and regeneration strategies represents
pathways (JAK/STAT, PKA, PI3K, MEK, Wnt/ a promising alternative for the treatment of ED.
Frizzled, ERK/MAPK, TGF-b, and insulin For such strategies to succeed, a reliable source of
growth factor [IGF]-I). PPP, a specific inhibitor smooth muscle precursor cells must be identified.
of IGF-I signaling, was the only inhibitor that In 2006, Rodriguez et al. checked the capacity of
showed significant inhibition of IBMX-induced ADSCs to differentiate into phenotypic and func-
ADSCs neuronal differentiation, as determined by tional SMCs in vitro [11]. The cells were cultured
changes in cell morphology in the initial screen- in smooth muscle differentiation medium for the
ing. Further examination by immunofluorescence differentiation. Smooth muscle differentiation of
staining showed that the neuronal marker, b-III- ADSCs induced genetic expression of all smooth
tubulin, was highly induced in IBMX-treated muscle markers and was further confirmed by
ADSCs, and the induction was significantly sup- increased protein expression of alpha-smooth
pressed by PPP. Western blotting followed by muscle actin (a-SMA), calponin, SM22, myosin
densitometry showed that PPP suppressed IBMX- heavy chain (MHC), and smoothelin. Clonal
induced b-III-tubulin expression by 43%, 88%, studies of adipose-derived multipotent cells dem-
and 84% when used to treat the cells for 1, 3, and onstrated differentiation of these cells into SMCs
24 hours, respectively. Treatment of ADSCs with in addition to trilineage differentiation capacity.
IBMX also led to the phosphorylation of IGF-I Importantly, smooth muscle-differentiated cells,
receptor at tyrosine 1136 (Y1136), as determined but not their precursors, exhibit the functional
by immunofluorescence staining with an antibody ability to contract and relax in direct response to

J Sex Med 2009;6(suppl 3):320–327