Percutaneous intrarenal transplantation of differentiated induced pluripotent stem cells into newborn mice

Abstract

The in vivo engraftment of induced pluripotent stem cell (iPSC)‐derived podocytes following allogeneic transplantation into host kidneys remains a challenge. Here we investigate the survival and engraftment of human dermal fibroblasts‐derived differentiated iPSCs using a newborn mouse model, which represents a receptive immunoprivileged host environment. iPSCs were generated from skin biopsies of patients using Sendai virus reprogramming. Differentiation of nephrin (NPHS1)‐green fluorescent protein (GFP) iPSCs into kidney podocytes (iPSC‐PODs) was performed by the addition of Activin A, bone morphogenetic protein 7 (BMP7), and retinoic acid over 10 days of culture. To assess the in vivo incorporation of cells, undifferentiated iPSCs or day 10 iPSC‐PODs, were labeled with either carboxyfluorescein succinimidyl ester (CFSE) or Qdot nanocrystals (Q705). Thereafter, 1 × 105 differentiated iPSC‐PODs were injected directly into the kidneys of mouse pups at postnatal day one (P1). Using co‐expression analysis of glomerular and podocyte‐specific markers, Day 10 differentiated iPSC‐PODs that were positive for podocin, were detected following direct kidney injection into newborn mice up to 1 week after transplantation. Undifferentiated iPSC‐PODs were not detected at the same timepoint. The transplanted cells were viable and located in the outer nephrogenic zone where they were found to colocalize with, or sit adjacent to, cells positive for glomerular‐specific markers including podocin, synaptopodin, and Wilms' tumor 1 (WT1). This study provides proof‐of‐principle that transplanted iPSC–POD can survive in recipient newborn mouse kidneys due to the immature and immunoprivileged nature of the developing postnatal kidneys.

Introduction to a special issue on kidney development and disease

“…Pluripotent stem cells have been the subject of much research intensity over recent decades, and Dr. Amander Clark (one of John's former PhD students) recounts their history in research, as well as the advances in technologies that may in future enable their successful application in renal regenerative medicine (Clark, 2020). In the first original research article in this issue, another former PhD student of John's (in fact, his first PhD student), Prof. Sharon Ricardo, describes a method of injecting induced pluripotent stem cells differentiated into podocytes (iPSC‐POD) into the immuno‐privileged environment of the neonatal mouse kidney (Lau, Al‐Rubaie, Saini, Wise, & Ricardo, 2020); these findings show great promise for iPSC‐POD co‐localization and survival in the host kidney.…”