| 1. |
- Hochgerner, Mathias, et al.
(författare)
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BMPR1a Is Required for the Optimal TGFβ1-Dependent CD207+ Langerhans Cell Differentiation and Limits Skin Inflammation through CD11c+ Cells
- 2022
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Ingår i: Journal of Investigative Dermatology. - : Elsevier BV. - 0022-202X. ; 142:9, s. 3-2454
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Tidskriftsartikel (refereegranskat)abstract
- The cytokine TGFβ1 induces epidermal Langerhans cell (LC) differentiation from human precursors, an effect mediated through BMPR1a/ALK3 signaling, as revealed from ectopic expression and receptor inhibition studies. Whether TGFβ1‒BMPR1a signaling is required for LC differentiation in vivo remained incompletely understood. We found that TGFβ1-deficient mice show defective perinatal expansion and differentiation of LCs. LCs can be identified within the normal healthy human epidermis by anti-BMPR1a immunohistology staining. Deletion of BMPR1a in all (vav+) hematopoietic cells revealed that BMPR1a is required for the efficient TGFβ1-dependent generation of CD207+ LC-like cells from CD11c+ intermediates in vitro. Similarly, BMPR1a was required for the optimal induction of CD207 by preformed major histocompatibility complex II‒positive epidermal resident LC precursors in the steady state. BMPR1a expression is strongly upregulated in epidermal cells in psoriatic lesions, and BMPR1aΔCD11c mice showed a defect in the resolution phase of allergic and psoriatic skin inflammation. Moreover, whereas LCs from these mice expressed CD207, BMPR1a counteracted LC activation and migration from skin explant cultures. Therefore, TGFβ1‒BMPR1a signaling seems to be required for the efficient induction of CD207 during LC differentiation in the steady state, and bone marrow‒derived lesional CD11c+ cells may limit established skin inflammation through enhanced BMPR1a signaling.
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| 2. |
- Liu, Yang, et al.
(författare)
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Successful gene therapy of Diamond-Blackfan anemia in a mouse model and human CD34+ cord blood hematopoietic stem cells using a clinically applicable lentiviral vector
- 2022
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 107:2, s. 446-456
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure disorder in which pure red blood cell aplasia is associated with physical malformations and a predisposition to cancer. Twentyfive percent of patients with DBA have mutations in a gene encoding ribosomal protein S19 (RPS19). Our previous proof-of-concept studies demonstrated that DBA phenotype could be successfully treated using lentiviral vectors in Rps19-deficient DBA mice. In our present study, we developed a clinically applicable single gene, self-inactivating lentiviral vector, containing the human RPS19 cDNA driven by the human elongation factor 1a short promoter, which can be used for clinical gene therapy development for RPS19-deficient DBA. We examined the efficacy and safety of the vector in a Rps19-deficient DBA mouse model and in human primary RPS19-deficient CD34+ cord blood cells. We observed that transduced Rps19-deficient bone marrow cells could reconstitute mice long-term and rescue the bone marrow failure and severe anemia observed in Rps19-deficient mice, with a low risk of mutagenesis and a highly polyclonal insertion site pattern. More importantly, the vector can also rescue impaired erythroid differentiation in human primary RPS19-deficient CD34+ cord blood hematopoietic stem cells. Collectively, our results demonstrate the efficacy and safety of using a clinically applicable lentiviral vector for the successful treatment of Rps19-deficient DBA in a mouse model and in human primary CD34+ cord blood cells. These findings show that this vector can be used to develop clinical gene therapy for RPS19-deficient DBA patients.
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| 3. |
- Safi, Fatemeh, et al.
(författare)
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Concurrent stem- and lineage-affiliated chromatin programs precede hematopoietic lineage restriction
- 2022
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 39:6
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Tidskriftsartikel (refereegranskat)abstract
- The emerging notion of hematopoietic stem and progenitor cells (HSPCs) as a low-primed cloud without sharply demarcated gene expression programs raises the question on how cellular-fate options emerge and at which stem-like stage lineage priming is initiated. Here, we investigate single-cell chromatin accessibility of Lineage-, cKit+, and Sca1+ (LSK) HSPCs spanning the early differentiation landscape. Application of a signal-processing algorithm to detect transition points corresponding to massive alterations in accessibility of 571 transcription factor motifs reveals a population of LSK FMS-like tyrosine kinase 3 (Flt3)intCD9high cells that concurrently display stem-like and lineage-affiliated chromatin signatures, pointing to a simultaneous gain of both lympho-myeloid and megakaryocyte-erythroid programs. Molecularly and functionally, these cells position between stem cells and committed progenitors and display multi-lineage capacity in vitro and in vivo but lack self-renewal activity. This integrative molecular analysis resolves the heterogeneity of cells along hematopoietic differentiation and permits investigation of chromatin-mediated transition between multipotency and lineage restriction.
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| 4. |
- Warsi, Sarah
(författare)
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Novel Insights into Haematopoietic Stem Cell Regulation and Function
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The haematopoietic stem cell (HSC) is a somatic stem cell essential for life long haematopoiesis; HSCs have the capability to differentiate into all mature types of blood cells and can also undergo self-renewal to maintain their own numbers. They also have the potential to reconstitute a complete haematopoietic system following HSC transplantation, also known as bone marrow transplantation, which is used to treat many haematopoietic disorders. To obtain successful long-term engraftment of HSCs, a large number of cells need to be transplanted. This limiting factor in the clinical use of HSC transplantation could be overcome by methods that expand and maintain HSCs ex vivo. Despite continuous progress in this field, efficient HSC expansion has had limited success in part due to limited knowledge on HSC regulation. Better understanding of how HSC fate options are governed in the HSCs’ natural environment can contribute to the development of future expansion protocols and improved HSC therapies. HSCs reside in the bone marrow and the fate of each HSC is tightly regulated by both intrinsic and extrinsic factors. The studies presented in this thesis have identified novel intrinsic regulatory factors for haematopoietic stem cell self-renewal and quiescence. In summary, our results demonstrate the importance of preserved SLFN2 and BMP signalling for proper HSC functionality. We show that loss of SLFN2 function in HSCs causes a defect in reconstitution potential of the HSCs by perturbing cell cycle status and stress response (Paper I). SLFN2 is known to regulate cell quiescence and apoptosis in other cell types and our data now shows that it plays a similar role in HSCs. Furthermore, we show that loss of BMP signalling also leads to a defect in HSC reconstitution potential, in part mediated via TJP1 (Paper II), which is a previously known regulator of self-renewal in other stem cells. Our study thus establishes a previously unknown role for BMP signalling in adult HSCs and demonstrates a putative connection between BMP and TJP1 in HSCs. HSC transplantation is today the only curative treatment for many haematopoietic disorders, but it is associated with many risks for the patients. Prior to HSC transplantation patients today undergo extensive conditioning, often involving irradiation or chemotherapy, which are independently associated with increased morbidity and mortality. As haematopoietic disorders often originate from the HSC itself, the HSCs are in many respects less fit than HSCs in a healthy individual. The work in this thesis also shows, using a mouse model of Diamond-Blackfan anaemia, that HSC transplantation can be successful even without conditioning or with a reduced conditioning regimen (Paper III), i.e. that the less fit HSCs can be out-competed by healthy HSCs. Taken together, we have identified novel factors that affect HSC function and fate options and provided insight into HSC transplantation in haematopoietic disorders.
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| 5. |
- Warsi, Sarah, et al.
(författare)
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Schlafen2 is a regulator of quiescence in adult murine hematopoietic stem cells
- 2022
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 107:12, s. 2884-2896
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Tidskriftsartikel (refereegranskat)abstract
- Even though hematopoietic stem cells (HSC) are characterized by their ability to self-renew and differentiate, they primarily reside in quiescence. Despite the immense importance of this quiescent state, its maintenance and regulation is still incompletely understood. Schlafen2 (Slfn2) is a cytoplasmic protein known to be involved in cell proliferation, differentiation, quiescence, interferon response, and regulation of the immune system. Interestingly, Slfn2 is highly expressed in primitive hematopoietic cells. In order to investigate the role of Slfn2 in the regulation of HSC we have studied HSC function in the elektra mouse model, where the elektra allele of the Slfn2 gene contains a point mutation causing loss of function of the Slfn2 protein. We found that homozygosity for the elektra allele caused a decrease of primitive hematopoietic compartments in murine bone marrow. We further found that transplantation of elektra bone marrow and purified HSC resulted in a significantly reduced regenerative capacity of HSC in competitive transplantation settings. Importantly, we found that a significantly higher fraction of elektra HSC (as compared to wild-type HSC) were actively cycling, suggesting that the mutation in Slfn2 increases HSC proliferation. This additionally caused an increased amount of apoptotic stem and progenitor cells. Taken together, our findings demonstrate that dysregulation of Slfn2 results in a functional deficiency of primitive hematopoietic cells, which is particularly reflected by a drastically impaired ability to reconstitute the hematopoietic system following transplantation and an increase in HSC proliferation. This study thus identifies Slfn2 as a novel and critical regulator of adult HSC and HSC quiescence.
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