Abstract
The clinical application of induced pluripotent stem cells (iPSC) needs to balance the use of an autologous source that would be a perfect match for the patient against any safety or efficacy issues that might arise with using cells from an older patient or donor. Drs. Takahashi and Yamanaka and the Office of Cellular and Tissue-based Products (PMDA), Japan, have had concerns over the existence of accumulated DNA mutations in the cells of older donors and the possibility of long-term negative effects. To mitigate the risk, they have chosen to partner with the Umbilical Cord (UC) banks in Japan to source allogeneic-matched donor cells. Production of iPSCs from UC blood cells (UCB) has been successful; however, reprogramming blood cells requires cell enrichment with columns or flow cytometry and specialized growth media. These requirements add to the cost of production and increase the manipulation of the cells, which complicates the regulatory approval process. Alternatively, umbilical cord tissue mesenchymal stromal cells (CT-MSCs) have the same advantage as UCB cells of being a source of young donor cells. Crucially, CT-MSCs are easier and less expensive to harvest and grow compared to UCB cells. Here, we demonstrate that CT-MSCs can be easily isolated without expensive enzymatic treatment or columns and reprogramed well using episomal vectors, which allow for the removal of the reprogramming factors after a few passages. Together the data indicates that CT-MSCs are a viable source of donor cells for the production of clinical-grade, patient matched iPSCs.
Highlights
cord tissue mesenchymal stromal cells (CT-mesenchymal stromal cells (MSCs)) were isolated from tissue explants (n = 13) and the morphology of the cells were routinely monitored
A viral-free and integration-free protocol to reprogram CT-MSCs into induced pluripotent stem cells (iPSC) using the episomal method in feeder-free conditions was established
The iPSC lines successfully differentiated into all three germ layers as tested with embryoid body culture and the teratoma assay
Summary
The advancements made over the past decade in cellular reprogramming have allowed for the first human clinical trials using autologous and allogeneic induced pluripotent stem cells (iPSCs) [1]. Changes had to be made to the reprogramming protocols so that the iPSCs were generated under integration-free, feeder-free and viralfree conditions. A major roadblock with the first-generation reprogramming vectors was that they were of viral origin that required integration into the genome. Since nonintegrating strategies, such as Sendai virus, episome and RNA, alleviate insertional risks such as mutagenesis, reactivation of silenced transgenes and tumorgenesis [2]. Episome reprogramming is currently being used in clinical trials in Japan [3]
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