NOVEL MICROSPHERES FOR PROLONGED CELL SURVIVAL - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 658

fulfillingtheneedsintheareaoftissueengineering.Anencapsulated
microspherebyitselfhasportrayedtremendouscharacteristicssuch
as controlled release of active reagents and the capability to encap-
sulate various compounds of biological importance, but neverthe-
lesstheseadvantagesfailtobeutilizeddirectlyasascaffoldduetoits
physical constraint. This is because a typical scaffold needs to meet
several basic criteria 53 : an extensive network with interconnecting
pores for cells migration, multiplication, and attachment; channels
toprovideoxygenandnutrientsandalsotoremovewasteproducts;
biocompatibility with a high a nity for cells to attach and prolifer-
ate; the right shape and size as desired by the surgeon; and appro-
priate mechanical strength and biodegradation profile.
TheconceptofacompositescaffoldutilizingORMsintissueengi-
neeringcanbeadopted. TheORMscanbeintegratedhomogenously
as part of the scaffold within the main matrix. The microspheres
act as an active microreactor that produces oxygen for the cells,
whilecellscanattach,proliferateanddifferentiate,andformanECM
on the specially designed scaffold. In this approach, there is also a
possibility to separate the oxygen-producing mechanisms into both
the matrices—encapsulation of the oxygen source such as H 2 O 2 in
microspheres and the grafting of decomposition reagents such as
catalaseonthescaffold.Asthesourceisreleasedatacontrolledrate,
itwill getdecomposed when in contact withthe scaffold matrix.
Integration of the microspheres can be done via various meth-
ods. One of the ways is by direct mixing of the microspheres
into the scaffold material during the construction of the three-
dimensional(3D)networkwhilethematerialisstillinsolutionform.
Upon being molded into the desired shape and size of the scaffold,
the microspheres will be evenly distributed within the matrix of
the scaffold to release oxygen for cell survival. Other approaches
include the entrapment technique, where microspheres are physi-
cally spread in between the networks of the scaffold. An example of
thatwillbetheelectrospinningofnanofibersintoarequesteddesign
(e.g., sheet, capillary, layered, etc.), and at the same time, ORMs are
spread evenly during the electrospinning process. By doing this,
microspheres will be knitted in between the porous fiber networks,
and cells can grow directly on the microspheres' surface, ensuring a
su cient and highlevel of oxygen supply.