Table 2.

An analysis of the MNPs for their use in stem cell tracking using MRI

Year	Type of MNP	How stem cells attached to SPIONs	Method of production of label	Clinical application	In vivo/in vitro	% of stem cells labeled	Effect on stem cells	How long the label remained detectable	Other
201148	Gold nanoparticle coated with PLL or citrate solution	Passive uptake of the nanoparticles by the cells	Gold nanoparticles coated with PLL added to cell culture and incubated for 24 hours	MSC labeling, imaging, and tracking	In vitro (LIVE/DEAD stain)	NR	Not cytotoxic to the cells and did not substantially affect viability	NR	Cell uptake of the nanoparticle decreased
201132	USPIO-PS	Passive uptake of the nanoparticles by the cells	USPIOs are composed of maghemite cores modified on their surface by amino silane coupling agents	Labeling of hADSCs to assess their fate in vivo on a three-dimensional, porous scaffold	Mouse	91%	Not toxic for the cells apart from a slight loss of metabolic activity at days 11 and 14 compared to the unlabelled cells	28 days after implantation	USPIO allowed the visualization of 5 × 104 labeled hADSCs by MRI
201165	FE-Pro	Passive uptake of the nanoparticles by the cells	Ferumoxide–protamine sulfate complex was made with ferumoxides mixed with protamine sulfate solution	Labeling hB MSCs with FE-Pro to be tracked by MRI	Ex vivo	95%	Did not harm cells or influence their behavior, including viability, long-term metabolic cell activity	NR	Transfection with protamine sulfate leads to a higher uptake
201166	Mesoporous silica-coated hollow manganese oxide (HMnO@mSiO2) nanoparticles	Electroporation	MnO nanoparticles were prepared, stabilized, and coated with a silica coating	MRI tracking of MSC using HMnO@mSiO2 as a positive marker	Mouse	26% with electroporation	Minimal impact on cell viability	14 days	Significantly higher relativity versus existing manganese oxide nanoparticles
201167	CoPt hollow nanoparticles	Passive uptake of the nanoparticles by the cells	CoPt nanoparticles were synthesized and coated with a mixture of PEG-SH and CCALNN peptide	MRI tracking of grafted NSCs labeled with CoPt	In vitro	NR	No impact on cell viability, morphology, or proliferation at low concentrations of CoPt nanoparticles	Detectable at low cell numbers with MRI after 2 weeks	Optimized when NSCs exposed to 8 mg mL−1 and 16 mg mL−1, and CoPt for 48 hours
200968	SPIONs with a carboxydextran coating	Passive uptake of the nanoparticles by the cells by endoplasmic absorbtion	MSCs culture medium was incubated for 24 h with Ferucarbotran	Labeling and therefore tracking MSCs in the kidney of a dog	Dog	PLL coating Has a higher labeling efficiency than ferumoxide	Impaired viability and/or apoptosis at higher conc. No affect on cell viability and proliferation	NR	Can label efficiently without transfer agent
200969	SPIO@SiO2-NH2	Passive uptake of the nanoparticles by the cells	Polyhedral crystalline SPIO nanoparticles were prepared by a coprecipitation method	Tracking MSCs using SPIO@SiO2-NH2 with MRI	Rabbit	Increased MSC-labeling effects	Displayed normal nuclear morphology, apoptosis, and necrosis changes were not observed	12 weeks	NR
201070	Chitosan–SPIONs coated in PLL	Passive uptake of the nanoparticle by the cells using endocytosis	Chitosan−SPIO synthesized by a sono-chemical method followed by a chitosan coating process	Label and track hBM−MSC using MRI	Rabbit	Almost 100%	Did not show any cytotoxicity up to a 200 mg Fe/mL concentration	2 weeks	NR
200760	MGIO	Passive uptake of the nanoparticles by the cells via endocytosis	Nonmagnetic PMG synthesized then magnetized by the coprecipitation of iron salt to form primary iron oxide cores within PMG	Labeling hfMSCs for MRI tracking with MGIO	Rat	97%	There was no affect on cellular proliferation	M600 particles could be detected even after four cellular divisions	M600 achieved a five- to sevenfold higher sensitivity for MRI detection than ferucarbotran
200971	SPION coated with starch	Passive uptake by the cells	SPIONs coated in starch were synthesized. Incubation with nanoparticles in the cell culture medium	Labeling and tracking MSCs using SPIONs	NR	Uptake was proven but not quantified	Cells able to differentiate into stromal tissue, including bone and fat	28 days; could visualize 1,000 MSCs	No MRI signal with the use of free iron- or dead iron-labeled MSCs

Abbreviations: MNPs, magnetic nanoparticles; MRI, magnetic resonance imaging; SPIONs, superparamagnetic nanoparticles; PLL, poly-L-lysine; MSC, mesenchymal cells; NR, not reported; USPIO-PS, ultrasmall superparamagnetic iron oxide; hADSCs, human adipose-derived stem cells; FE-PRO, ferumoxide-protamine sulfate complex; hB, human bone; CoPt, cobalt platinum; PEG-SH, polyethylene glycol; CCALNN, cysteine-cystein-alanine-leucine-asparagine; NSC, neural stem cells; SPIO, superparamagnetic iron oxide; MGIO, microgel iron oxide; PMG, precursor microgel; hfMSC, human fetal mesenchymal cells.