Differential Sensitivity to JAK Inhibitory Drugs by Isogenic Human Erythroblasts and Hematopoietic Progenitors Generated from Patient-Specific Induced Pluripotent Stem Cells

Abstract

Disease-specific induced pluripotent stem cells (iPSCs) provide an unprecedented opportunity to establish novel disease models and accelerate drug development using distinct tissue target cells generated from isogenic iPSC lines with and without disease-causing mutations. To realize the potential of iPSCs in modeling acquired diseases which are usually heterogeneous, we have generated multiple iPSC lines including two lines that are JAK2-wild-type and four lines homozygous for JAK2-V617F somatic mutation from a single polycythemia vera (PV) patient blood. In vitro differentiation of the same patient-derived iPSC lines have demonstrated the differential contributions of their parental hematopoietic clones to the abnormal erythropoiesis including the formation of endogenous erythroid colonies. This iPSC approach thus may provide unique and valuable insights into the genetic events responsible for disease development. To examine the potential of iPSCs in drug testing, we generated isogenic hematopoietic progenitors and erythroblasts from the same iPSC lines derived from PV patients and normal donors. Their response to three clinical JAK inhibitors, INCB018424 (Ruxolitinib), TG101348 (SAR302503), and the more recent CYT387 was evaluated. All three drugs similarly inhibited erythropoiesis from normal and PV iPSC lines containing the wild-type JAK2 genotype, as well as those containing a homozygous or heterozygous JAK2-V617F activating mutation that showed increased erythropoiesis without a JAK inhibitor. However, the JAK inhibitors had less inhibitory effect on the self-renewal of CD341 hematopoietic progenitors. The iPSC-mediated disease modeling thus underlies the ineffectiveness of the current JAK inhibitors and provides a modeling system to develop better targeted therapies for the JAK2 mutated hematopoiesis.

Erythroid differentiation of human induced pluripotent stem cells is independent of donor cell type of origin

“…The successful reprogramming of erythroid progenitors derived from patients with polycythemia vera has been described recently. 44 In a recent study our iPSC derived from mouse NSC with OCT4 alone showed reduced neuronal and hematoendothelial differentiation compared to iPSC reprogrammed with all four factors or ESC. 45 This might be the result of some epigenetic instability, as shown in the DNA methylation pattern of the pluripotency associated promoters, although their gene expression profile was very similar to that of ESC.…”

Efficient and Allele-Specific Genome Editing of Disease Loci in Human iPSCs

“…For this purpose, we again chose to target the somatic JAK2-V617F (rs77375493, G>T) mutation and the inherited α1-antitrypsin (AAT) Z mutation (rs28929474, G>A) in the SERPINA1 gene. Two panels of healthy donor and patient-derived iPSCs carrying either a homozygous wild-type target allele, heterozygous mutant allele or homozygous mutant allele were used in these experiments [26,28,[32][33][34] (Table 1). Two gRNAs, gRNA-JAK2-F and gRNA-JAK2-V, were designed with a single nucleotide difference to specifically recognize the V617F mutant allele (T) or the wild-type allele (G) of JAK2 (Fig 4a).…”

Patient-derived induced pluripotent stem cells in cancer research and precision oncology

“…1). Normal iPSCs that genetically match the malignant iPSCs can be derived from the same cancer patients to provide paired tumor and normal iPSCs that share the same genetic background 29,31,33 . These can be derived in parallel, through the same reprogramming experiment from normal cells that frequently ‘contaminate’ a tumor specimen, and identified retrospectively through genetic analyses 29,31 .…”