Generation of human hematopoietic stem cells from induced pluripotent stem cells. – HEMPLUS

Despite much work by a large number of research teams, the ex vivo manufacture of clinically-grade, transplantable human hematopoietic stem cells (HSCs) has not yet been achieved. Two teams have recently published the conversion of adult endothelial cells or human induced pluripotent stem cells (hiPSCsIPSCs) into HSCs. However, this production depends on the introduction of 5 to 7 transgenes into the cells, which prevents their use in cell therapy. There is therefore an urgent need to establish new procedures to produce HSCs de novo. This lack of knowledge has a profound impact on therapies, weighs heavily on health budgets and is responsible for the poor quality of life of patients suffering from hematological diseases.
This collaborative project brings together 3 teams with strong complementary expertise in biological and clinical hematopoiesis with a major common objective: to improve HSC transplantation by deciphering how to generate a safe and robust cell population capable of grafting into bone marrow and giving rise to bona fide adult HSCs.
We have recently developed a unique, one-step, transgene and stroma-free, GMP-transposable, single-step protocol for the production of HSCs from hiPSCs. This new procedure is based on directed differentiation of embryonic bodies (EB) with morphogens and cytokines to generate a population of human cells capable of producing multi-linear hematopoiesis in immunocompromised sequential recipient mice. This demonstrates that transgene-free generation of human HSCs from hiPSCs is possible.
In order to progress to the clinic, we need a thorough cellular and molecular characterization of graft-capable cells and a robust assay in a preclinical model. Our objectives are to 1° to characterize in EB the evolution of the cell population with reconstitution capacity using single cell transcriptomic approaches and cell trajectory reconstructions in order to identify the cells at the origin of HSCs ; 2° To identify the minimum cell population to be transplanted and its potential by analyzing, using single cell transcriptomics, barcoding and cell tracing approaches, which cell population(s) is (are) transplanted into murine bone marrow and the underlying mechanisms giving rise to the production of HSCs ; 3° to demonstrate that these cells can contribute to long-term multi-linear hematopoiesis in the preclinical model of the Göttingen mini-pig compared to CD34 cells from cord blood. In order to ensure the safety of the graft for clinical application, the genomic stability of the graft will also be accurately studied.
This work paves the way for the generation of clinical grade HSCs for the treatment of hematological diseases in allogeneic and even autologous conditions. Our work will provide in-depth knowledge and multi-scale analysis of the transcriptomic landscape of human HSCs and their hiPSC-derived precursors. Achieving these objectives will lead to important changes in therapeutic management, increasing the accessibility of HSC transplantation, in order to improve the care, quality of life and survival of patients treated for hemopathy. It will also reduce the overall cost of treating hematological malignancies and create wealth by leading to new patentable discoveries.