NOVEL MICROSPHERES FOR PROLONGED CELL SURVIVAL - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 659

32.4.2 Oxygen-Generating Reservoir
The small size of the microsphere requires extra handling cau-
tion when used for tissue engineering applications so as to avoid
the interference effect that may be caused by its high mobility.
Unless integrated within a fixed position, as discussed earlier, the
microspheres will have the possibility of being washed away by the
present biofluid to other sensitive areas and subsequently cause a
serious contamination problem. For example, if the ORMs are used
to provide oxygen at a wound for faster tissue regeneration, with-
out integration, the microspheres may go into the bloodstream via
injured or cut vessels and get circulated to other parts of the body.
Thiscancauseseriousproblemsandthemalfunctionofthoseorgans
due to the presence ofthe microspheres.
In overcoming such a problem, direct usage of microspheres to
the targeted area can be avoided, and instead a delivery system can
be employed that can supply oxygen to the cells. This means the
ORMs will act as a reservoir to generate oxygen without direct con-
tact with the cells. In this case, the medium on the targeted area
is constantly circulated through the microspheres that are confined
within membrane barriers to saturate its oxygen level. Upon reach-
ingthecells,diffusionofoxygenoccursfromthehighlyconcentrated
fluidic phase to the cells. Such an approach is more suitable to be
applied for an in vitro system such as those using microfluidic chan-
nels for the supply of nutrients to cells.
32.4.3 Medicine to Oxygenate Tissues
The failure in supplying enough oxygen to organs causes serious
damage to their functionality and subsequently can paralyze a nor-
mally operating biological system. One of the well-known examples
is stroke, caused by the blockage of the cerebral microvasculature
and resulting in decreased blood and nutrient supply postocclusion
to the brain tissue. 81 This ischemic and hypoxic environment leads
to several necrotic tissue events, including the loss of adenosine
triphosphate (ATP) production, elevated levels of intracellular cal-
cium, etc., that ultimately lead to neuronal and cerebrovascular cell
death. 82 Undersuchconditions,itwillbeusefultoemploytheORMs