Selectively eliminating residual human induced pluripotent stem cells (iPSCs) in cell mixtures for cell therapy

Brandeis University, Waltham MA

Investigators

Abstract

Abstract Human-induced pluripotent stem cells (iPSCs) hold tremendous promise for cell therapy. However, the significant tumorigenic risk associated with residual iPSCs in cell mixture during cell transplantation remains a major obstacle to their clinical applications. To address this challenge, we have assembled a multidisciplinary team consisting of a biomaterials chemist (Xu) and a stem cell biologist (Lu). Our goal is to develop and evaluate transient intranuclear peptide assemblies (nPAs) to selectively eliminate residual iPSCs without impacting iPSC- derived cells in cell mixture—an unmet need in the field. We recently achieved selectively eliminating iPSCs without harming iPSC-derived hematopoietic progenitor cells (HPCs) using transient nPA. This selectivity hinges on the well-documented overexpression of alkaline phosphatase (ALP) in iPSCs. ALP catalytically dephosphorylates a phospho-L-peptide precursor, forming transient nPAs capable of eliminating iPSCs. This nPA precursor exhibits exceptional selectivity, rapidly eradicating iPSCs in cell mixture within 2 hours due to three key factors: (i) iPSCs express high levels of ALP, (ii) ALP expression decreases significantly in iPSC- derived and normal cells, and (iii) nPAs comprise L-peptides that undergo proteolysis within the cellular environment. However, it remains to be verified whether nPA precursors/building blocks would affect iPSC- derived cells beyond HPCs and whether the elimination of residual iPSCs in the cell mixture is sufficient to prevent tumor formation from the cell transplantation in vivo. Additionally, the design principles governing nPA precursors have yet to be established. Therefore, we propose to explore nPAs for eliminating residual iPSCs from cell mixtures containing iPSCs and iPSC-derived photoreceptor precursor cells (PPCs) by the studies focusing on three specific aims: Aim 1: Design, synthesize, and characterize nPA precursors to conduct a preliminary structural-to-activity relationship (SAR) study. Aim 2: Evaluate nPAs on iPSCs and iPSC-derived photoreceptor precursor cells (PPCs) using cell assays. Aim 3: Examining the efficacy of nPAs to prevent tumor formation from cell transplantation using a standard murine model. The successful completion of these studies will provide a novel approach to eliminate residual iPSCs rapidly and selectively in cell mixtures, substantially enhancing its safety profile of transplantation of iPSC-derived cells and thereby improving the treatment of various human diseases.