By Will Soutter
in Stem Cell Therapy
References and Further Reading
Regenerative medicine attempts to restore living tissue which has been
lost or damaged. It is a highly interdisciplinary field which has only
been made possible by the intersection of recent advances in stem cell
therapy, bioengineering, and nanotechnology.
Nanofabrication techniques now allow researchers to create nanofibre
scaffolds for regenerative therapies. The exact way this works depends
on the nature of the tissue, but in general the scaffolds are used to
guide the growth of new tissue, seeded using stem cells.
Figure 1. Stem cells can be
used to regrow damaged tissue in many areas of the body. Nanoscale
scaffolds can improve results of stem cell therapy by guiding this
growth in the right direction. Image credit: National Eye Institute.
Most nanofibres which have been used in regenerative medicine
research are produced using the electrospinning method. This is a
well-established technique, which allows a degree of control over the
properties of the resulting nanofibre sheets or meshes, and is suited
to a wide range of natural and synthetic fibre materials.
Whilst nanofibres are well suited to use as biological scaffolds,
they are only useful in their untreated state as a 2D support - the
pores within the 3D nanofibre mesh are too small to support cell
Some research has investigated the use of porogens in the
electrospinning process - dopants which trigger the formation of
micron-scale pores within the nanopore mesh.
Another type of nanofibre which has proved effective in regenerative
medicine is made from peptides which spontaneously form stable networks
of nanofibres. This is driven by interactions between hydrophobic and
hydrophilic regions of the peptide chain.
These peptide nanofibres can be functionalized with specific
terminals to add additional capabilities, such as receptor-binding
sites or growth hormones.
The precise requirements for the nanofibre scaffold depend on the
type of tissue which is being regrown. Below, some of the types of
tissues which researchers have worked with are summarized.
Functionalized peptide nanofibres have been shown to assist the
treatment of ischaemic heart disease, which is caused by fatty deposits
in the coronary arteries. Stem cell treatments had previously been
attempted, but the benefits werre unclear. Using self-assembled peptide
nanofibres functionalized with insulin growth factor as a delivery
method was shown to improve cardiac function.
Bone consists or a mineral matrix, embedded with a wide variety of
biological structures. Stem cells grown on a nanofibre scaffold can be
used to regenerate this complex structure successfully. The scaffold
materials which give the best results are made from a mixture of
collagen, nano-structured titanium, electro-spun silk fibres, and
nanostructured hydroxyapatite (the calcium phosphate-based mineral
which makes up much of bone's solid structure).
Deficiency of limbal stem cells, the reservoir of stem cells used
for natural repairs to the cornea, is currently treated with a
transplant of cultured stem cells on human amniotic membrane - silk or
collagen-based scaffolds have been developed as potential alternatives.
This method is now also showing promise as a method of treating
corneal injuries, using electrospun nanofibres as the carrier medium
for the stem cells. Both limbal and mesenchymal stem cells have been
shown to improve corneal healing, and reduce the local inflammatory
Neural Tissue Engineering
Rebuilding neural tissue is one of the biggest challenges to
regenerative medicine. It has a very complex structure, and the
environment tends to inhibit the tissue's natural capability to
Scaffolds of polymer nanofibres with stem cells have been shown to
prevent the formation of scar tissue in spinal injuries, preventing the
"communication block" that can occur when the spinal cord is damaged.
Breakout Labs, the Thiel Foundations's research
supports a number of biotech companies working in the field of stem
cell research and regenerative medicine.
The newest addition to the
roster, Bell Biosystems, is developing a technology to
help track therapeutic stem cells in the body using MRI.
Labels in Stem Cell Therapy
Nanotechnology has also provided valuable tools for stem cell
research. Magnetic nanoparticles can be attached to the cells before
they are transplanted into the body in cell therapy trials. They can
then act as contrast agents, helping to track the cells in the body via
The most common nanoparticle contrast agents are superparamagnetic iron
oxide nanoparticles. These typically consist of a crystalline core of
iron oxide, with an inert polymer shell which prevents agglomeration of
the particles and minimizes interactions with the cells. These nano
contrast agents have been approved by the FDA, and are commercially
available from a number of suppliers.
Superparamagnetic nanoparticles have been used successfully to track
stem cell fate in the central nervous system, heart, liver, and kidneys.
Recent progress in the field of nanotechnology has allowed
corresponding rapid progress in regenerative medicine, particularly in
biocompatible nanoscaffolds and tissue engineering.
A great deal of ongoing research is leading towards complete
reconstruction of damaged tissue, including the nervous system, bone,
blood vessels, and potentially whole organs, by utilizing the tools and
materials provided by nanotechnology in conjunction with stem cell
therapy. This is just one more way in which nanotechnology is gradually
transforming the world of medicine.
References and Further
- "Functionalized Nanostructures with Applications in
Regenerative Medicine" - M. Perán et al, International Journal of
Molecular Sciences, 2012. DOI: 10.3390/ijms13033847
- "Nanotechnologies in Regenerative Medicine" - Š. Kubinová
& Eva Syková, Minimally Invasive Therapy, 2010. DOI: 10.3109/13645706.2010.481398
- "Nanotechnology for Regenerative Medicine" - D. Khang et
al, Biomed Microdevices, 2010. DOI: 10.1007/s10544-008-9264-6