Biomedical Engineering Reference
In-Depth Information
made with the NGF microencapsulation, increasing the stability and controlling the release
of recombinant NGF, however this type of microcapsules was not enough.
There are various potential micro-implants employed for the treatment of neurological and
neurodegenerative disorders, such as polymeric nanoparticles, microcapsules, hydrogels, or
liposomes.
5.1 Nanoparticles
The advent of nanotechnology can provide a solution to overcome the future diagnostic and
new neurotherapeutic challenges for neurodegenerative diseases as Alzheimer's disease and
Parkinson's disease. This technology employs engineered materials with the smallest
functional organization on the nanometre scale that are able to interact with biological
systems at the molecular level. Nanoparticles are able to penetrate the blood brain barrier
of
in vitro
and
in vivo
models disrupting the temporally the barrier and allowing the
incorporation the therapeutic agents into the brain (Rempe et al, 2011). One interesting
pathway to reach introduce drugs with nanoparticles into the brain can be with previous
phagocytise using immune cells that are able to across the blood brain barrier. For example,
there is an invention where involves delivering a drug by using macrophages present in the
patient's cerebrospinal fluid that are capable to reaching the brain transporting the drug.
This particular mode of delivery utilizing macrophages needs of previous uptake by the
macrophages of nanoparticles loaded with the drug. The great advantage of this
methodology is that these cells are not limited to macrophages, it is possible the use of
monocytes, granulocytes, neutrophils, basophils and eosinophils.
Major future and promising uses of nanoparticles can therefore be to develop diagnostic
tools. For example, amyloid plaques are one of the pathological hallmarks of Alzheimer's
disease, the visualization of amyloid plaques in the brain is important to monitor the
progression of this disease and to evaluate the efficacy of therapeutic interventions.
Recently, many groups are developing new contrast agents to detect amyloid plaques
in vivo
using ultrasmall superparamagnetic iron oxide nanoparticles, chemically coupled with
amyloid-beta (1-42) peptide to detect amyloid deposition (Yang et al, 2011). Further,
nanoparticles are currently being used to refine the discovery of biomarkers and molecular
diagnostics, which could be applicable to the management of neurodegenerative and
neurological diseases (Sahni et al, 2010). Current pharmacotherapies for neurodegenerative
diseases that have been successfully encapsulated in nanoparticles are polyphenolic
compounds, (EGCG, apolipoprotein E containing curcumin or resveratrol), hormones
(estradiol, melatonin, vasoactive intestinal peptide) and amyloid targeted drugs (thioflavin-
T and S, coenzyme Q10, amyloid or gold).
5.2 Microcapsules
The technology of cell microencapsulation represents a strategy in which cells that secrete
therapeutic products are immobilized and immunoprotected within polymeric and
biocompatible devices (Orive et al, 2003b). One of the main advantages of cell
microencapsulation is for the treatment of neurological disorders, where some drugs have
potential therapeutic possibilities, such as growth factors or peptides, however only at low
and constant concentrations. These microcapsules implants are able to secrete only the drug
required by the damaged tissue, because the implants with microencapsulated cell are
formed by live cells. These immobilized live cells that over-express the drug are able to
