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Human Bone Marrow Microenvironment in Health and Disease

Bräunig, Sandro LU (2023) In Lund University, Faculty of Medicine Doctoral Dissertation Series
Abstract
Hematopoietic stem cells (HSCs) are safeguarded from various threats such as stress, injury, or radiation
within specialized microenvironments or niches within the bone marrow. In this thesis, we investigated
various facets of the bone marrow (BM) microenvironment and its critical role in hematopoiesis and
related disorders.
Initially, we elucidated the role of the Early Growth Response 1 (EGR1) gene in bone marrow
mesenchymal stem cells (MSCs). EGR1 expression was found to be significantly elevated in specific BM
MSC populations, particularly lin-CD45-CD271+ CD140a- BM MSCs, exerting a pivotal role in
hematopoietic stroma support. This support function was mediated through both cell-cell interactions... (More)
Hematopoietic stem cells (HSCs) are safeguarded from various threats such as stress, injury, or radiation
within specialized microenvironments or niches within the bone marrow. In this thesis, we investigated
various facets of the bone marrow (BM) microenvironment and its critical role in hematopoiesis and
related disorders.
Initially, we elucidated the role of the Early Growth Response 1 (EGR1) gene in bone marrow
mesenchymal stem cells (MSCs). EGR1 expression was found to be significantly elevated in specific BM
MSC populations, particularly lin-CD45-CD271+ CD140a- BM MSCs, exerting a pivotal role in
hematopoietic stroma support. This support function was mediated through both cell-cell interactions and
soluble factors, where EGR1-overexpressing BM MSCs exhibited enhanced secretion of chemokine
ligand 28 and increased expression of vascular cell adhesion molecule 1, crucial for hematopoiesis
support. EGR1 also played a dual role in BM MSC proliferation regulation. Understanding these
mechanisms can improve hematopoietic stem cell transplantation and regenerative medicine.
Further, employing single-cell RNA sequencing, we provided a comprehensive analysis of the cellular
composition of human BM stroma, revealing diverse cell populations and stromal progenitors with varying
differentiation capacities. We identified and characterized multipotent stromal stem cells (MSSCs), highly
adipocytic gene-expressing progenitors (HAGEPs), pre-osteoblasts, and other stromal clusters, offering
valuable insights into BM stromal heterogeneity and its structural organization. We employed in silico
cluster interaction analysis and found that the different stromal populations are predicted to interact and
support HSCs differentially in different niches.
Next, we introduced a meticulous methodology utilizing multicolor immunofluorescence staining and 3D
analysis to investigate human BM architecture. We illustrated the potential of sequential staining,
emphasizing specific structural changes associated with myeloproliferative neoplasms (MPNs) and their
correlation with CD271 expression.
Finally, we investigated human BM architecture and cytokine expression patterns in patients with Acute
Lymphoblastic Leukemia (ALL) and Primary Myelofib(PMF) with elaborate immunofluorescence and
mRNA-based staining methods and compared them to healthy controls. We revealed significant
alterations, including differential numbers of megakaryocytes, differences in cellularity, altered
mesenchymal stem cell density, and distinct cytokine expressions offering critical insights into disease
pathogenesis and progression.
Collectively, these findings illuminate various facets of the BM microenvironment, offering valuable
insights into its critical role in hematopoiesis, stromal heterogeneity, and disease pathology, paving the
way for potential therapeutic advancements in regenerative medicine and hematological disorders. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • MD, Ph.D., Ass.Prof. Reinisch, Andreas, Division of Hematology & Department of Blood Group Serology and Transfusion Medicine, Medical University Graz, Graz, Austria
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Hematopoietic microenvironment, Imaging, Myeloproliferative neoplasms, Spatial relationships, acute lymphoblastic leukaemia (ALL), Fibrosis, Mesenchymal stromal cell, Single cell RNA sequencing
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
issue
2023:141
pages
89 pages
publisher
Lund University, Faculty of Medicine
defense location
Segerfalksalen, BMC A10, Sölvegatan 17 i Lund
defense date
2023-11-24 09:00:00
ISSN
1652-8220
ISBN
978-91-8021-483-4
language
English
LU publication?
yes
id
8f864320-95aa-4fa9-a341-d24fb8998791
date added to LUP
2023-10-31 10:27:28
date last changed
2023-11-06 10:23:31
@phdthesis{8f864320-95aa-4fa9-a341-d24fb8998791,
  abstract     = {{Hematopoietic stem cells (HSCs) are safeguarded from various threats such as stress, injury, or radiation<br/>within specialized microenvironments or niches within the bone marrow. In this thesis, we investigated<br/>various facets of the bone marrow (BM) microenvironment and its critical role in hematopoiesis and<br/>related disorders.<br/>Initially, we elucidated the role of the Early Growth Response 1 (EGR1) gene in bone marrow<br/>mesenchymal stem cells (MSCs). EGR1 expression was found to be significantly elevated in specific BM<br/>MSC populations, particularly lin-CD45-CD271+ CD140a- BM MSCs, exerting a pivotal role in<br/>hematopoietic stroma support. This support function was mediated through both cell-cell interactions and<br/>soluble factors, where EGR1-overexpressing BM MSCs exhibited enhanced secretion of chemokine<br/>ligand 28 and increased expression of vascular cell adhesion molecule 1, crucial for hematopoiesis<br/>support. EGR1 also played a dual role in BM MSC proliferation regulation. Understanding these<br/>mechanisms can improve hematopoietic stem cell transplantation and regenerative medicine.<br/>Further, employing single-cell RNA sequencing, we provided a comprehensive analysis of the cellular<br/>composition of human BM stroma, revealing diverse cell populations and stromal progenitors with varying<br/>differentiation capacities. We identified and characterized multipotent stromal stem cells (MSSCs), highly<br/>adipocytic gene-expressing progenitors (HAGEPs), pre-osteoblasts, and other stromal clusters, offering<br/>valuable insights into BM stromal heterogeneity and its structural organization. We employed in silico<br/>cluster interaction analysis and found that the different stromal populations are predicted to interact and<br/>support HSCs differentially in different niches.<br/>Next, we introduced a meticulous methodology utilizing multicolor immunofluorescence staining and 3D<br/>analysis to investigate human BM architecture. We illustrated the potential of sequential staining,<br/>emphasizing specific structural changes associated with myeloproliferative neoplasms (MPNs) and their<br/>correlation with CD271 expression.<br/>Finally, we investigated human BM architecture and cytokine expression patterns in patients with Acute<br/>Lymphoblastic Leukemia (ALL) and Primary Myelofib(PMF) with elaborate immunofluorescence and<br/>mRNA-based staining methods and compared them to healthy controls. We revealed significant<br/>alterations, including differential numbers of megakaryocytes, differences in cellularity, altered<br/>mesenchymal stem cell density, and distinct cytokine expressions offering critical insights into disease<br/>pathogenesis and progression.<br/>Collectively, these findings illuminate various facets of the BM microenvironment, offering valuable<br/>insights into its critical role in hematopoiesis, stromal heterogeneity, and disease pathology, paving the<br/>way for potential therapeutic advancements in regenerative medicine and hematological disorders.}},
  author       = {{Bräunig, Sandro}},
  isbn         = {{978-91-8021-483-4}},
  issn         = {{1652-8220}},
  keywords     = {{Hematopoietic microenvironment; Imaging; Myeloproliferative neoplasms; Spatial relationships; acute lymphoblastic leukaemia (ALL); Fibrosis; Mesenchymal stromal cell; Single cell RNA sequencing}},
  language     = {{eng}},
  number       = {{2023:141}},
  publisher    = {{Lund University, Faculty of Medicine}},
  school       = {{Lund University}},
  series       = {{Lund University, Faculty of Medicine Doctoral Dissertation Series}},
  title        = {{Human Bone Marrow Microenvironment in Health and Disease}},
  url          = {{https://lup.lub.lu.se/search/files/163413322/Sandro_Shari_Nil_Serge_Br_unig_WEBB.pdf}},
  year         = {{2023}},
}