الفهرس 
Skin structure and function
Improvement of Cutaneous Flap SurvivalOnly 14 pages are availabe for public view
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Abstract
Random-pattern skin flap is one of the most widely used tools in the
repair of tissue defects in plastic surgery. However, its utility is limited
by unpredictable blood supply, which sometimes results in partial flap
necrosis which represents a great challenge.
This problem therefore limits the use of random-pattern skin flaps.
Different methods to improve skin flap survival have been employed
which may be pharmacological or surgical. Surgical delay and ischemic
preconditioning is the most effective method of increasing survival area.
However, the delay procedure requires an additional operative procedure.
Many researchers have focused on drug therapy as an alternative method
for augmenting blood flow rather than the time consuming surgical delay.
The pharmacological drugs mimics the surgical delay, however, the effects
of drugs are transient and unstable.
VEGF, bFGF, PDGF, and TGF-β has been shown to augment flap
vascularity and reduce skin flap necrosis. However, their utility is limited
by their short duration and the need for high doses and frequent injections
which leads to many side effects.
Stem cells have emerged as a key element of regenerative medicine.
Stem cell therapy has aroused an interest in improving flap survival,
especially bone marrow derived stem cells and adipose derived stem cells.
Supplemental administration of angiogenic growth factors such as BMMSCs
transplantation has many advantages including abundance in the
bone marrow and easy isolation. BM-MSCs are also a heterogenous
population of cells, which have been shown more beneficial than
homogenous composition in therapeutic vascularization. Also high levels
of angiogenic growth factors such as VEGF and bFGF could be maintained by transplanted BM-MSCs. In addition BM-MSCs can be
transplanted directly without in vitro expansion. All these properties make
BMSCs a good source of mesenchymal stem cells.
BM-MSCs exert their effect by their ability to produce angiogenic
growth factors such as VEGF, PDGF, and bFGF. Also, BM-MSCs could
differentiate into endothelial cells to participate in neovascularization.
In our research, we studied the role of bone marrow derived stem cells
whether cultured under normoxic or hypoxic conditions on the random
skin flap survival in a rat model, and the optimal timing for administration
of these cells.
Our study consisted of three main groups; group A injected with
normoxic bone marrow stem cells, group B injected with hypoxic bone
marrow derived stem cells and group C which is the control group, Each
group is further subdivided into two subgroups according to the time of
flap injection, The subgroup 1 is injected at time of flap elevation, and
subgroup 2 which is injected one week before flap elevation. Flap survival
was evaluated on the seventh postoperative day by: the percentage of flap
survival, capillary density and VEGF level by ELISA.
BM-MSCs showed statistically significant increase in skin flap
viability when injected simultaneously with time of flap elevation,
however, BM-MSCs had no effect on flap survival when injected one
week preoperatively. The maximal effect was observed when the hypoxic
cells were injected simultaneously with flap elevation. This was in
accordant with the significant increase of the capillary density and VEGF
expression.