Table 1.

The advantages and disadvantages of different reprogramming methods for induction of pluripotent stem cells

Methods	Type	Subtypes	Advantages or disadvantages
Gene delivery methods	Viral delivery system	Lentivirus	Advantages
			- Infect both dividing and non-dividing cells
			- Recombinant can be pseudotyped to broaden tropism
			- Highly efficient
			- Constitutive and inducible expression can be attained
			Disadvantage
			- Integration into host genome
		Retrovirus	Advantages
			- Undergo silencing in ES cells
			- Highly efficient
			Disadvantage
			- Integration into host genome
		Adenovirus	Advantage
			- Non-integrating vector
			Disadvantages
			- Poor gene transfer
			- Control of gene expression level difficult
	Non-viral system	Episomal plasmids	Advantages
			- Non-integrating vector
			- Able to replicate autonomously giving rise to prolonged expression
			Disadvantage
			- Low reprogramming efficiency
	Excision strategies	Cre-loxP recombination	Advantages
			- Gene expression profile closer to hES cells compared to human iPS cells
			- Efficient excision of integrated transgenes
			Disadvantages
			- Genomic instability and genome rearrangements
			- loxP site remain integrated in genome
		piggyBac transposon	Advantages
			- Self-excision
			- Precise and efficient excision
			Disadvantage
			- pBt gene may remain active post-transposition
Non-DNA methods	Protein-mediated	Poly-arginine peptide tags	Advantages
			- Reprogrammed cells from embryonic fibroblast cells were indistinguishable from the classic embryonic stem cells
			Disadvantages
			- Not clear is can be used for adult cells
			- Short half-life
	Manipulation of cell-culture conditions	Oxygen level manipulation	Advantages
			- No genetic manipulation
			- No protein carriers needed
			Disadvantage
			- Short-term induction
	miRNAs	miR-294, miR-302	Advantages
			- Able to replace c-Myc
			- Increased efficiency
			Disadvantages
			- Not specific
			- Target point may be too upstream in the cell signalling pathway
			- Expression not easily controlled post-induction
Enhancing DNA reprogramming efficiencies	Small molecules and soluble factors	Chromatin modification modifiers	Advantages
			- Modulate chromatin modification
			- Target cell-signalling pathways
			Disadvantage
			- Non-specific and broad action
			- May cause dysregulation of gene expression