Table 2.

Methods of delivery for reprogramming factors

Method	Advantages	Disadvantages
Retroviral transduction	Efficient, validated for multiple cell types, easy	Transgene integration
Lentiviral delivery	Very efficient	Transgene integration
Adenoviral transduction	Does not integrate	Low efficiency, only validated for fibroblasts
Plasmid DNA transfer (episomal)	Good efficiency, does not integrate, able to replicate autonomously, validated for multiple cell types	Low efficiency in fibroblast reprogramming
Lox p lentivirus delivery	High efficiency, excision of the integrated sequence, gene expression profile closer to hES cells	Genomic instability and genome rearrangements and loxP site remains integrated
Sendai virus	Efficient, does not integrate, validated for multiple cell types	Cost if purchased commercially or challenging if generated by a laboratory
PiggyBAC transposon	Efficient, precise and efficient self-excision, does not remain integrated	Published work only in fibroblasts, licensing patent issues, pBt gene may remain active post-transposition
Polyarginine tagged polypeptide	Does not integrate	Low efficiency, time-consuming, technically challenging and work only on fibroblasts
RNA modified synthetic mRNA	Very efficient, does not integrate, factor available commercially	Cost if purchased commercially or challenging if generated by a laboratory and work only on fibroblasts