Table 1.

Transgene-based and transgene-free methods of reprogramming. (C—CHIR, F—FSK, K—Klf4, L—Lin28, M—c-Myc, N—Nanog, O—Oct4, S—Sox2, T—TTNPB, V—VPA, Z—DZNep and 6—616452). (All efficiencies for reprogramming are indicated as the percentage for the number of induced pluripotent stem cell (iPSC) colonies as compared to the original number of seeded cells).

Method Type	Method	Factors/Other Agents	Cell Type	References	Efficiency
Transgene-based	Retroviral	OSKM	Mouse fibroblasts	[6]	0.02%
	Retroviral + small molecules	OSKM + SB431542 + PD0325901	Human fibroblasts	[23]	~1%
	Lentiviral	OSNL	Mouse fibroblasts, human fibroblasts	[18]	0.0095%
	Inducible lentiviral	OSKMN	Human fibroblasts, keratinocytes	[19]	1%–3%
	Integrating, non-viral inducible plasmid vectors	OSKM	Rat fibroblasts	[20]	0.0027%–0.0078%
Transgene-free	Small molecules	C6FZ or VC6TFZ	Mouse fibroblasts	[29]	0.2%
	Episomal plasmids	OSKM	Mouse fibroblasts	[17]	~0.1%
	Sendai viruses	OSKM	Human fibroblasts	[32]	~1%
	Non-integrating DNA adenoviral	OSKM	Tail tip fibroblasts, hepatocytes, fatal liver cells	[34]	0.0001%–0.001%
	Excisable lentiviral	OSK	Mouse fibroblasts, human fibroblasts	[36]	Not reported
	PiggyBAC transposon	OSKM or OSKML	Mouse fibroblasts	[38]	~1%
	Synthetic mRNA	OSKM	Human fibroblasts	[39]	2%
	Polyarginine-tagged polypeptides	OSKM	Human fibroblasts	[42]	0.001%
	Magnet-based nanofection of polypeptides	OSKM	Mouse fibroblasts	[43]	0.001%–0.003%
	MicroRNAs (lentiviral)	miR302/367	Mouse fibroblasts, human fibroblasts	[44]	Up to 10%