Induced pluripotent stem cells (iPSC) represent a potentially exciting regenerative-medicine cell therapy for several chronic conditions such as macular degeneration, soft tissue and orthopedic conditions, cardiopulmonary disease, cancer, neurodegenerative disorders and metabolic disorders. The field of iPSC therapeutics currently exists at an early stage of development. There are several important stakeholders that include academia, industry, regulatory agencies, financial institutions and patients who are committed to advance the field. Yet, unlike more established therapeutic modalities like small and large molecules, iPSC therapies pose significant unique challenges with respect to safety, potency, genetic stability, immunogenicity, tumorgenicity, cell reproducibility, scalability and engraftment. The aim of this review article is to highlight the unique technical challenges that need to be addressed before iPSC technology can be fully realized as a cell replacement therapy. Additionally, this manuscript offers some potential solutions and identifies areas of focus that should be considered in order for the iPSC field to achieve its promise. The scope of this article covers the following areas: (1) the impact of different iPSC reprogramming methods on immunogenicity and tumorigenicity; (2) the effect of genetic instability on cell reproducibility and differentiation; (3) the role of growth factors and post-translational modification on differentiation and cell scalability; (4) the potential use of gene editing in improving iPSC differentiation; (5) the advantages and disadvantages between autologous and allogeneic cell therapy; (6) the regulatory considerations in developing a viable and reproducible cell product; and (7) the impact of local tissue inflammation on cell engraftment and cell viability.

AIMA virus- and oncogene-free induced pluripotent stem cell (iPSC) reprogramming method was developed with cord blood-derived mononuclear cells (CBDMNC) and peripheral blood mononuclear cells (PBMNC) from patients with genetic lung diseases.METHODiPSC reprogramming used small molecules, hematopoietic stem cell (HSC) expansion media and episomal vectors that lacked Myc and Lin28.RESULTSAll iPSC colonies were fully reprogrammed based on SSEA4 expression. A total of 300,000 CBDMNC was the optimal cell number for cell reprogramming, which was associated with a 13-fold increase in CD34+ cells upon exposure to HSC media. Cell reprogramming was not observed in the absence of HSC expansion media. The method also reprogrammed PBMNC in patients with cystic fibrosis or α-1 antitrypsin deficiency. Oncogene-free iPSC cell lines differentiated into all three germ cell lineages.CONCLUSIONThis iPSC reprogramming approach satisfies an important regulatory requirement for iPSC-based cell therapies with lower clinical risk from CBDMNC and PBMNC.

Aim: Nonviral induced pluripotent stem cell (IPSC) reprogramming is not efficient without the oncogenes, Myc and Lin28. We describe a robust Myc and Lin28-free IPSC reprogramming approach using reprogramming molecules. Methods: IPSC colony formation was compared in the presence and absence of Myc and Lin28 by the mixture of reprogramming molecules and episomal vectors. Results: While more colonies were observed in cultures transfected with the aforementioned oncogenes, the Myc and Lin28-free method achieved the same reprogramming efficiency as reports that used these oncogenes. Further, all colonies were fully reprogrammed based on expression of SSEA4, even in the absence of Myc and Lin28. Conclusion: This approach satisfies an important regulatory pathway for developing IPSC cell therapies with lower clinical risk.