Stem cells as delivery vehicles for regenerative medicine-challenges and perspectives

Table 1 Advantages and disadvantages of the different types of nanoparticles used for stem cell loading

Composition	Type	Advantages	Disadvantages	Payload	Homing to	Ref.
Polymeric NP	Poly(D,L-lactide), poly(D,L-lactic acid-co-α,β-malic acid),Poly-L-lactic acid	Biocompatible, FDA approved, versatility, efficient upload by stem cells, human HSCs, MSCs retain differentiation potential	Biphasic and uncontrolled payload release	Antitumour drugs,	Glioma tumours	[77-79]
Silica NP	Mesoporous silica, amorphous silica	Fast uptake, negligible toxicity, long retention inside cells, lysosomal activation not associated with oxidative stress	Long term remanence within cells/tissues	Antitumour drug doxorubicin, fluorescent dye, paclitaxel	Mammary tumours, infarcted heart	[80-82,92]
Liposomal NP	Liposomes	Relatively facile manufacturing, versatility for drug delivery	Less-efficient uptake process, higher concentrations needed, which can be toxic to cells	6-coumarin	Glioma tumours	[83]
Magnetic nanoparticles	Iron oxide NPs, magnetite, maghemite	Cellular tracking potential, reduced cell toxicity, high loading efficiency	Can induce oxidative stress in carrier cells	NGF, FGF	Dorsal root ganglia, HUVECs	[84-86]

NP: Nanoparticle; NGF: Nerve growth factor; FGF: Fibroblast growth factor; HUVECs: Human umbilical endothelial vein cells.