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Multiple Endocrine Neoplasia Type 2B (MEN2B) is a cancer-predisposing syndrome that affects patients with germline RET mutations. The clinical spectrum of the syndrome includes medullary thyroid carcinoma (MTC) and pheochromocytoma. Currently, there is no satisfactory model recapitulating all the features of the disease especially at the level of stem cells. We generated induced pluripotent stem cells (iPSCs) from a patient with RET mutation at codon 918 who developed pheochromocytoma and MTC. These iPSC had normal karyotype, harboured the RETM918T mutation and expressed pluripotency hallmarks. A comprehensive pathological assessment of teratoma was performed after injection in immunodeficient mice.

Multiple Endocrine Neoplasia Type 2A (MEN2A) is a cancer-predisposing syndrome that affects patients with germline RET mutations. The clinical spectrum of the syndrome includes medullary thyroid carcinoma (MTC), pheochromocytoma, hyperparathyroidism and cutaneous lichen amyloidosis (CLA) and/or Hirschsprung disease in some variants. Currently, there is no satisfactory animal model recapitulating all the features of the disease especially at the level of stem cells. We generated induced pluripotent stem cells (iPSCs) from a patient with RET mutation at codon 634 who developed pheochromocytoma and MTC. RETC634Y-mutated cells were reprogrammed by non-integrative viral transduction. These iPSCs had normal karyotype, harboured the RETC634Y mutation and expressed pluripotency hallmarks as well as RET. A comprehensive pathological assessment of teratoma was performed after injection in immunodeficient mice.

Chronic myeloid leukemia (CML) is a clonal malignancy initiated by the occurrence of a t (9;22) translocation, generating Ph1 chromosome and BCR-ABL oncogene in a primitive hematopoietic stem cell (HSC). The resistance of HSC to targeted therapies using tyrosine kinase inhibitors remains a major obstacle towards the cure. We have generated an iPSC line from a patient with CML using leukemic CD34+ cells cryopreserved at diagnosis. Ph1+ CML cells were reprogrammed by non-integrative viral transduction. These iPSCs harboured Ph1 chromosome and expressed pluripotency hallmarks as well as BCR-ABL. Teratoma assays revealed normal differentiation after injection in immunodeficient mice.

Recent development of cell reprogramming technologies brought a major hope for future cell therapy applications by the use of these cells or their derivatives. For this purpose, one of the major requirements is the absence of genomic alterations generating a risk of cell transformation. Here we analyzed by microarray-based comparative genomic hybridization human iPSC generated by two non-integrative and one integrative method at pluripotent stage as well as in corresponding teratomas. We show that all iPSC lines exhibit copy number variations (CNV) of several genes deregulated in oncogenesis. These cancer-associated genomic alterations were more pronounced in virally programmed hiPSCs and their derivative teratoma as compared to those found in iPSC generated by mRNA-mediated reprogramming. Bioinformatics analysis showed the involvement of these genes in human leukemia and carcinoma. We conclude that genetic screening should become a standard procedure to ensure that hiPSCs are free from cancer-associated genomic alterations before clinical use., Competing Interests: CONFLICTS OF INTEREST There are no conflicts of interest to disclose.

MEN2A is a hereditary cancer-predisposing syndrome that affects patients with germline RET mutations. The effects of this oncogenic tyrosine kinase in the context of primitive stem cells are not known. In order to study these events, we generated a MEN2A induced Pluripotent Stem Cell (iPSC) line from a patient with RET mutation and an isogenic counterpart by CRISPR-Cas9 correction of the mutation. Whole exome sequencing of iPSC before and after CRISPR-Cas9 genome edition revealed no major exonic off target effect of the CRISPR correction. However, an integrative differential gene expression analysis of iPSC with oncogenic RET C634Y and its gene-corrected iPSC with RET Y634C as well as RET wt iPSCs revealed activation of the Early Growth Response 1 (EGR1) transcriptional program in RET-mutated iPSC, a pathway shown to be involved in RET-induced oncogenesis. These data constitute the first proof of concept of the feasibility of the use of an iPSC and its genome-corrected counterpart to unravel the molecular mechanisms underlying the development of the hereditary MEN2A cancer predisposing syndrome., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

BRCA1 germline mutation confers hereditary predisposition for breast and ovarian cancer. To understand the physiopathology of mammary and ovarian epithelial cancer transformation, and to identify early driver molecular events, we have generated an iPSC line from a patient carrying a germline exon 17 deletion in BRCA1 gene (BRAC1Ex17 iPSC) in a high-risk family context. Blood cells were reprogrammed used non-integrative virus of Sendaï. The BRCA1-deleted iPSC had normal karyotype, harboured a deletion in the exon 17 of the BRCA1 gene, expressed pluripotent hallmarks and had the differentiation capacity into the three germ layers., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

We report here the first use of whole-genome sequencing (WGS) to examine the initial clonal dynamics in an unusual patient with chronic myeloid leukemia (CML), who presented in chronic phase (CP) with doubly marked BCR-ABL1 + /JAK2 V617F -mutant cells and, over a 9-year period, progressed into an accelerated phase (AP) and then terminal blast phase (BP). WGS revealed that the diagnostic cells also contained mutations in ASXL1, SEC23B, MAD1L1, and RREB1 as well as 12,000 additional uncommon DNA variants. WGS of endothelial cells generated from circulating precursors revealed many of these were shared with the CML clone. Surprisingly, WGS of induced pluripotent stem cells (iPSCs) derived from the AP cells revealed only six additional coding somatic mutations, despite retention by the hematopoietic progeny of the parental AP cell levels of BCR-ABL1 expression and sensitivity to imatinib and pimozide. Limited analysis of BP cells revealed independent subclonal progression to homozygosity of the MAD1L1 and RREB1 variants. MAD1L1 and SEC23B mutations were also identified in 2 of 101 cases of myeloproliferative neoplasms, but not in 42 healthy subjects. These findings challenge historic concepts of clonal evolution in CML., (Copyright © 2017 ISEH - International Society for Experimental Hematology. All rights reserved.)

Multiple Endocrine Neoplasia Type 2B (MEN2B) is a cancer-predisposing syndrome that affects patients with germline RET mutations. The clinical spectrum of the syndrome includes medullary thyroid carcinoma (MTC) and pheochromocytoma. Currently, there is no satisfactory model recapitulating all the features of the disease especially at the level of stem cells. We generated induced pluripotent stem cells (iPSCs) from a patient with RET mutation at codon 918 who developed pheochromocytoma and MTC. These iPSC had normal karyotype, harboured the RET M918T mutation and expressed pluripotency hallmarks. A comprehensive pathological assessment of teratoma was performed after injection in immunodeficient mice., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Chronic myeloid leukemia (CML) is a clonal malignancy initiated by the occurrence of a t (9;22) translocation, generating Ph1 chromosome and BCR-ABL oncogene in a primitive hematopoietic stem cell (HSC). The resistance of HSC to targeted therapies using tyrosine kinase inhibitors remains a major obstacle towards the cure. We have generated an iPSC line from a patient with CML using leukemic CD34+ cells cryopreserved at diagnosis. Ph1+ CML cells were reprogrammed by non-integrative viral transduction. These iPSCs harboured Ph1 chromosome and expressed pluripotency hallmarks as well as BCR-ABL. Teratoma assays revealed normal differentiation after injection in immunodeficient mice., (Copyright © 2016 Helmholtz Zentrum München. Published by Elsevier B.V. All rights reserved.)

Multiple Endocrine Neoplasia Type 2A (MEN2A) is a cancer-predisposing syndrome that affects patients with germline RET mutations. The clinical spectrum of the syndrome includes medullary thyroid carcinoma (MTC), pheochromocytoma, hyperparathyroidism and cutaneous lichen amyloidosis (CLA) and/or Hirschsprung disease in some variants. Currently, there is no satisfactory animal model recapitulating all the features of the disease especially at the level of stem cells. We generated induced pluripotent stem cells (iPSCs) from a patient with RET mutation at codon 634 who developed pheochromocytoma and MTC. RET C634Y -mutated cells were reprogrammed by non-integrative viral transduction. These iPSCs had normal karyotype, harboured the RET C634Y mutation and expressed pluripotency hallmarks as well as RET. A comprehensive pathological assessment of teratoma was performed after injection in immunodeficient mice., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Hematopoiesis generated from human embryonic stem cells (ES) and induced pluripotent stem cells (iPS) are unprecedented resources for cell therapy. We compared hematopoietic differentiation potentials from ES and iPS cell lines originated from various donors and derived them using integrative and non-integrative vectors. Significant differences in differentiation toward hematopoietic lineage were observed among ES and iPS. The ability of engraftment of iPS or ES-derived cells in NOG mice varied among the lines with low levels of chimerism. iPS generated from ES cell-derived mesenchymal stem cells (MSC) reproduce a similar hematopoietic outcome compared to their parental ES cell line. We were not able to identify any specific hematopoietic transcription factors that allow to distinguish between good versus poor hematopoiesis in undifferentiated ES or iPS cell lines. There is a relatively unpredictable variation in hematopoietic differentiation between ES and iPS cell lines that could not be predicted based on phenotype or gene expression of the undifferentiated cells. These results demonstrate the influence of genetic background in variation of hematopoietic potential rather than the reprogramming process.

During human embryonic stem cell (ESC) hematopoietic differentiation, the description of the initial steps of lymphopoiesis remains elusive. Using a two-step culture procedure, we identified two original populations of ESC-derived hematopoietic progenitor cells (HPCs) with CD34(+)CD45RA(+)CD7(-) and CD34(+)CD45RA(+)CD7(+) phenotypes. Bulk cultures and limiting dilution assays, culture with MS5 cells in the presence of Notch ligand Delta-like-1 (DL-1), and ex vivo colonization tests using fetal thymic organ cultures showed that although CD34(+)CD45RA(+)CD7(-) HPCs could generate cells of the three lymphoid lineages, their potential was skewed toward the B cell lineages. In contrast, CD34(+)CD45RA(+)CD7(+) HPCs predominantly exhibited a T/natural killer (NK) cell differentiation potential. Furthermore these cells could differentiate equivalently into cells of the granulo-macrophagic lineage and dendritic cells and lacked erythroid potential. Expression profiling of 18 markers by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that CD34(+)CD45RA(+)CD7(-) and CD34(+)CD45RA(+)CD7(+) HPCs express genes of the lymphoid specification and that CD34(+)CD45RA(+)CD7(-) cells express B-cell-associated genes, while CD34(+)CD45RA(+)CD7(+) HPCs display a T-cell molecular profile. Altogether, these findings indicate that CD34(+)CD45RA(+)CD7(-) and CD34(+)CD45RA(+)CD7(+) HPCs correspond to candidate multipotent early lymphoid progenitors polarized toward either the B or T/NK lineage, respectively. This work should improve our understanding of the early steps of lymphopoiesis from pluripotent stem cells and pave the way for the production of lymphocytes for cell-based immunotherapy and lymphoid development studies.