Induced pluripotent stem cells: Mechanisms, achievements and perspectives in farm animals

Abstract

Pluripotent stem cells are unspecialized cells with unlimited self-renewal, and they can be triggered to differentiate into desired specialized cell types. These features provide the basis for an unlimited cell source for innovative cell therapies. Pluripotent cells also allow to study developmental pathways, and to employ them or their differentiated cell derivatives in pharmaceutical testing and biotechnological applications. Via blastocyst complementation, pluripotent cells are a favoured tool for the generation of genetically modified mice. The recently established technology to generate an induced pluripotency status by ectopic co-expression of the transcription factors Oct4, Sox2, Klf4 and c-Myc allows to extending these applications to farm animal species, for which the derivation of genuine embryonic stem cells was not successful so far. Most induced pluripotent stem (iPS) cells are generated by retroviral or lentiviral transduction of reprogramming factors. Multiple viral integrations into the genome may cause insertional mutagenesis and may increase the risk of tumour formation. Non-integration methods have been reported to overcome the safety concerns associated with retro and lentiviral-derived iPS cells, such as transient expression of the reprogramming factors using episomal plasmids, and direct delivery of reprogramming mRNAs or proteins. In this review, we focus on the mechanisms of cellular reprogramming and current methods used to induce pluripotency. We also highlight problems associated with the generation of iPS cells. An increased understanding of the fundamental mechanisms underlying pluripotency and refining the methodology of iPS cell generation will have a profound impact on future development and application in regenerative medicine and reproductive biotechnology of farm animals.

Derivation and Characterization of Bovine Induced Pluripotent Stem Cells by Transposon-Mediated Reprogramming

“…Retroviral and lentiviral delivery of core reprogramming factors allowed the derivation of iPSCs from several other mammals, including rat (Liao et al, 2009), dog (Shimada et al, 2010), pig (Esteban et al, 2009), rhesus monkey (Liu et al, 2008), sheep (Bao et al, 2011), goat , horse (Nagy et al, 2011), cattle (Han et al, 2011), buffalo (Deng et al, 2012), and of iPS-like cells from nonmammalian vertebrates (Rossello et al, 2013). iPSCs derived from somatic tissue are particularly promising in farm animals in which true, germline-competent embryonic stem cells (ESCs) could not yet be derived (Kumar et al, 2015). Previous approaches to derive bovine iPSCs employed retroviral (Han et al, 2011;Sumer et al, 2011), or lentiviral transduction (Cao et al, 2012) or plasmids (Huang et al, 2011;Wang et al 2013).…”

Pluripotent stem cells and livestock genetic engineering

“…Despite intensive efforts, establishment of robust bona fide ESCs in livestock species has been unsuccessful (Reviewed by Blomberg and Telugu 2012; Gandolfi 2012; Goncalves 2014; Koh and Piedrahita 2014; Kumar et al 2015; Malaver-Ortega et al 2012; Nowak-Imialek and Niemann 2012; Park and Telugu 2013; Telugu et al 2010b). In general, embryo-isolated cells have not demonstrated robust self-renewal and have typically failed to show in vivo pluripotency by teratoma formation assay.…”

“…On the other hand, reprogramming somatic cells to a pluripotent state has demonstrated some level of success (Goncalves et al 2014; Kumar et al 2015; Park and Telugu 2013). Pluripotency has been induced in a number of domestic species including cattle, goats, horses, pigs and sheep (for details see Table 1).…”

Methylation profile of bovine Oct4 gene coding region in relation to three germ layers

“…iPSCs actually induced cells to ESCs-like states by cellular reprogramming. Oct4, Nanog, Sox2, Klf4, c-Myc and Lin28 are the core inducing factors (Kumar et al 2015). Oct4 drive the transition from somatic cells to iPSCs together with Nanog and Sox2 (Herreros-Villanueva et al 2014).…”