Increasing numbers of requests for transplantable organs and their scarcity has led to a pressing need to
find alternative solutions to standard transplantation. An appealing but challenging proposal came from the fields
of tissue engineering and regenerative medicine, the purpose of which is to build tissues/organs from scratch in
the laboratory and use them as either permanent substitutes for direct implantation into the patient’s body, or as
temporary substitutes to bridge patients until organ regeneration or transplantation. Using bioartificial constructs
requires administration of immunosuppressant therapies to prevent rejection by the recipient.
Microencapsulation has been identified as promising technology for immunoisolating biological materials from
immune system attacks by the patient. It is based on entrapping cellular material within a spherical semipermeable
polymeric scaffold. This latter defines the boundary between the internal native-like environment and
the external “aggressive” one. The scaffold thus acts like a selective filter that makes possible an appropriate
supply of nutrients and oxygen to the cellular constructs, while blocking the passage for adverse molecules. Alginate,
which is a natural polymer, is the main biomaterial used in this context. Its excellent properties and mild
gelation ability provide suitable conditions for supporting viability and preserving the functionalities of the cellular-
engineered constructs over long periods. Although much remains to be done before bringing microencapsulated
constructs into clinical practice, an increasing number of applications for alginate-based microencapsulation
in numerous medical areas confirm the considerable potential for this technology in providing a cure for transplant
in patients that excludes immunosuppressive therapies.
Keywords: Tissue engineering, regenerative medicine, encapsulation, alginate beads, transplantation, extracorporeal supply.
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