Imaging in Stem Cell Transplant and Cell-based Therapy

31

2.7 Conclusions

With over 2000 clinical trials involving stem cells underway, it is critical that meth-
ods to deliver and track stem cells in vivo are optimized. While nanotechnology can
be of significant assistance, there are important concerns that need to be addressed
prior to mainstream clinical applications. The loss of contrast of nanoparticles as
stem cells proliferate and differentiate in  vivo, as well as the low efficiency and
specificity of in situ labeling of endogenous stem cells are areas of great interest and
challenge. Beyond tracking cells, it is of extreme importance to determine whether
stem cells are viable and have differentiated into functional target tissue, and at this
stage this often requires a variety of complementary imaging techniques. Toxicity of
magnetic and metal particles is still unclear and requires thorough long-term pre-
clinical testing. Nevertheless, as technologies and techniques advance, biomaterials
will likely be essential in delivery, assurance of viability, labelling and tracking of
stem cells in a variety of medical applications.

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2 Nanotechnology-Based Stem Cell Applications and Imaging