Over the past decade, the field of cell therapy has rapidly expanded with the aim to replace and repair damaged cells and/or tissue. Depending on the disease many different cell types can be used as part of such a therapy. In this collaborative project between the groups of Prof. Simon P. Hoerstrup and Prof. Roger M. Nitsch, we focus on treatment of myocardial infarction and stroke, where currently available treatment options are not able to regenerate the loss of healthy heart or brain tissue. We either use cardiomyocytes (CM) or neuronal precursor cells (NPC) differentiated from human induced pluripotent stem cells (iPSCs). For clinical translation of such technologies the use of xenofree, good manufacturing practice (GMP)-compliant protocols and quality controls are indispensable. In particular the purification of cells is of high importance, given the risk of teratoma formation upon transplantation of not fully differentiated or impure cell populations.
So far, we have reprogrammed human peripheral blood mononuclear cells into iPSCs using Sendai virus and then differentiated into either CM or NPC using chemically defined, 2D differentiation protocols. CM showed a beating phenotype, with the expression of specific cardiac markers and absence of pluripotency markers at RNA and protein level. In parallel, NPCs can be expanded and are stable for several passages. Immunohistochemistry and qPCR confirmed the expression of typical NPC markers and the downregulation of pluripotency genes. Using microRNA-responsive synthetic mRNAs (RNA switches) we have established - in collaboration with Center for iPS Cell Research and Application (CiRA), Kyoto University - the purification of iPSC-derived cells and elimination of iPSC, respectively.
Overall, the principal feasibility of differentiating CM and NPC under clinical-grade levels has been shown. The use of GMP-compliant differentiation protocols ab initio will facilitate the clinical translation of this project in later stages. Moreover, RNA switches are useful to purify desired cell types and minimize the risk of aberrant cell types. In the future, we aim to specifically functionalize and target these cells towards the specific ischemic environment of myocardial infarction or stroke for next generation cell-based therapies.