## 3 Application of Nanotechnology in Stem-Cell Therapy
### Nanotechnology Application for Monitoring Stem-Cell Therapy Progress  
The effective treatments for AD rely on the early diagnosis by detection and quantitation of AD biomarkers. With its relatively large size and being located intercellularly, amyloid \(\beta\) (A\(\beta\)) can be considered as a suitable imaging biomarker. Therefore, tracking the deposition of A\(\beta\) is one of the primary histopathologic methods to control AD progress [71]. By MRI technique, accumulated amyloid \(\beta\) plaques and inflammatory responses of neurons can be detected via anti-amyloid targeted superparamagnetic IONPs. The SPIONs have beneficial for improve the MRI sensitivity acting as in vivo or in vitro contrast agents (CAs) and thus have unique potential for biomedical applications, namely as MRI CAs (Figure 6) [72]. Moreover, gold nanoparticles (AuNPs) due to their gold core have several specific optical features, namely plasmonic properties, which make them ideal candidates for  
Figure 5: Intraoperative transplantation of stem cells carrying drug-loaded nanoparticles into the human brain post-tumor resection. Chronological order of the events that take place post-surgical transplantation. Here, stem-cell carrier tumor-tropic migration results in a targeted drug release in infiltrative tumor zones. Modified cell carriers contribute to the local toxic effects caused by the drug-loaded system in neoplastic areas. Stem-cell immunosuppressive properties hide loaded nanocarriers from the host-immune system and facilitate targeted anti-giloma therapy. Adapted with some modification from [70], [PERSON] et al., 2013.  
imaging applications. In particular, surface plasmon resonance (SPR) of gold particles is the resonation of surface conduction electrons induced by the oscillating electromagnetic wave generated by light striking the particles. By these optic features, AuNPs through X-ray and micro-CT scanning can absorb and reduce X-rays more efficiently than traditional CT contrast agents. Development of NSC transplantation approach has led to considerable progress in reducing central nervous system damage or restitute the brain function [73]. A better understanding of the position of transplanted NSCs has improved the efficiency of this approach. Cell tracking methods have revealed the potential of optimizing transplantation therapy via providing accurate picture of the fate and area effect of implanted cells. The main obstacle in application of stem-cell therapies at the clinical-scale is the evaluation of the precise location of implanted cells and the status of graft host cells in vivo [74]. Until recent years, mapping the in vivo control over specific differentiation, dynamic behavior and dispensation of implanted cells were major issues of this technique. In vivo imaging of transplanted cells is based on tagging these cells and following their differentiation from host tissue, like the brain (Figure 7) [75]. Figure 6: The application of iron oxide nanoparticles (IONPs) in diagnosis and treatment of Alzheimer’s disease (AD). Since amyloid \(\beta\) (A\(\beta\)) has been identified as an ideal imaging biomarker of AD at present, with the help of magnetic resonance imaging (MRI), IONPs can be used for the detection of A\(\beta\) to assist in diagnosis and treatment of AD. In vitro, magnetic nanoparticles (MNPs) labeled with antibodies against A\(\beta\)-40 and A\(\beta\)-42 is applicable to detect A\(\beta\) in the blood. Conjugated with the A\(\beta\) oligomer aptamer and the complementary oligonucleotide of the A\(\beta\) oligomer aptamer, IONPs can be developed as a method to measure the A\(\beta\) oligomer in the artificial cerebrospinal fluid (CSF). DDNP-superparamagnetic iron oxide nanoparticles (SPIONs) with high affinities to A\(\beta\) aggregates can be detected by fluorophotometry.