An important risk of iPSC therapy is associated with using lentiviruses or retroviruses. These viruses, although are genetically tailored to hold the genes required for an iPSC state transformation, will integrate into the host cell genome and consequently add multiple viral integration sites and be the cause for several safety issues (Howe et al., 2008). However, it should be noted that much control was gained over this process as the viral integration site can be determined in iPSCs using Cre-mediated strategies for instance or by using adenoviruses, plasmids, transposons, recombinant proteins, Sendai virus vectors and modified RNA (Herberts et al., 2011). It should be further noted that there has been worries of a state of dedifferentiation or dedifferentiation into an unwanted cell type once transplanted to humans, though this remains clinically unclear. Therefore, there has to be a thorough consideration of all the suspected risk factors before setting into iPSCs human clinical trials.
