Biomedical Engineering Reference
In-Depth Information
used to refine the discovery of biomarkers, molecular diagnostics, drug discovery, and drug
delivery, which could be applicable to the management of serious neurodegenerative
diseases such as Alzheimer's disease or Parkinson's disease.
The other great promise in the treatment of neurodegenerative diseases is the
microencapsulation of cell types secreting bioactive substances locally in the damage area of
the brain. The main handicap for the delivery of potentially therapeutic drugs to the brain is
hindered by the different blood brain barriers, which restricts the diffusion of drugs from
the vasculature to the brain parenchyma. One means of overcoming the blood brain barrier
is with cellular implants that produce and deliver therapeutic molecules. Polymer
encapsulation, or immunoisolation, provides a means of overcoming the blood brain barrier
to deliver therapeutic molecules directly into the central nervous system region of interest.
Immunoisolation is based on the observation that xenogeneic cells can be protected from
host rejection by encapsulating, or surrounding, them within an immunoisolatory, semi
permeable membrane. Cells can be enclosed within a selective, semi permeable membrane
barrier that admits oxygen and required nutrients and releases bioactive cell secretions, but
restricts passage of larger cytotoxic agents from the host immune defence system. The
selective membrane eliminates the need for chronic immunosuppression of the host and
allows the implanted cells to be obtained from nonhuman sources.
Nutrient
Drug
Living
Microcapsul
Immune
Fig. 1. Scheme of microcapsules containing living cells.
