The Molecular Mechanisms Controlling Maintenance Of Osteogenic Precursor Cells And Skeletal Tissue Regeneration
Funder
National Health and Medical Research Council
Funding Amount
$234,750.00
Summary
Within human bone marrow there exists a rare population of bone marrow stromal stem cells (BMSSCs) able to develop into the different cell types that form haematopoietic supportive stroma and surrounding skeletal tissue. There has been alot of interest of late in the potential of BMSSCs as a cellular based therapy to treat and manage bone fractures or bone loss caused by disease. Increasing evidence suggests that decreased bone mass due to osteoporosis dos not purely result in an increase of bon ....Within human bone marrow there exists a rare population of bone marrow stromal stem cells (BMSSCs) able to develop into the different cell types that form haematopoietic supportive stroma and surrounding skeletal tissue. There has been alot of interest of late in the potential of BMSSCs as a cellular based therapy to treat and manage bone fractures or bone loss caused by disease. Increasing evidence suggests that decreased bone mass due to osteoporosis dos not purely result in an increase of bone resorption by osteoclasts, but may also occur through a decline in the number of bone forming cells called osteoblasts or their progenitors. Fracture non-union, prosthetic loosening and the replacement of large defects in bone are common and difficult problems. The use of autologous bone cells generated from isolated BMSSCs in combination with bio-compatible implant materials would provide a novel solution for the treatment of these problems, avoiding the use of autografts and allografts of bone with all their associated difficulties. However, large numbers of ex vivo expanded BMSSCs are currently required to heal even small bone defects in animal models. This is compounded by the decline in proliferation rates and bone forming capacity of BMSSCs during prolonged expansion in culture. An improved understanding of the genes that regulate the proliferation and differentiation of BMSSCs in vitro is therefore an essential prerequisite for the effective management of bone fracture and bone loss. We propose to genetically manipulate the expression of genes in BMSSCs, that are known to regulate cellular growth and development inorder to maintain the growth of stem cell populations in vitro and to extend their capacity to form bone when transplanted in vivo.Read moreRead less
Hematopoietic Effects Of Activating The Hedgehog Pathway.
Funder
National Health and Medical Research Council
Funding Amount
$410,551.00
Summary
The hedgehog proteins are important for normal human development. They are expressed on cells of the brain and developing limbs and provide important signals to neighbouring cells so that development of the brain and limbs can occur normally. Mutations in genes within the hedgehog signalling pathway lead to congenital abnormalities such as failure of the brain to fold properly and shortened limbs or extra digits. Hedgehog proteins also stimulate the growth of adult stem cells that are responsibl ....The hedgehog proteins are important for normal human development. They are expressed on cells of the brain and developing limbs and provide important signals to neighbouring cells so that development of the brain and limbs can occur normally. Mutations in genes within the hedgehog signalling pathway lead to congenital abnormalities such as failure of the brain to fold properly and shortened limbs or extra digits. Hedgehog proteins also stimulate the growth of adult stem cells that are responsible for the maintenance of many adult tissues such as the skin, bone and hair. Excessive hedgehog signalling however can lead to cancers, particularly of the brain and skin. The ability of hedgehog proteins to stimulate the growth of stem cells raises their use for expansion of stem cells. This would be particularly useful for umbilical cord blood stem cells, which could be used to treat patients with leukemia if there were sufficient numbers. This project will examine the potential use of hedgehog proteins for stimulating blood stem cells.Read moreRead less
Characterisation Of Human Embryonic Stem Cell Differentiation To Haematopoietic Progenitors And Stem Cells
Funder
National Health and Medical Research Council
Funding Amount
$638,856.00
Summary
Blood stem cells, which are found in the bone marrow, are currently used for treating human blood disorders including leukemia and lymphoma. However, for the majority of bone marrow transplant candidates, suitable donors cannot be found. Using embryonic stem cells, this project aims to define the conditions required to generate blood stem cells in the laboratory. The aim of the work is to provide a new source of blood stem cells that could be used in place of donor derived bone marrow.
The Role Of Hyaluronic Acid In The Biology Of Haemopoietic Stem Cells
Funder
National Health and Medical Research Council
Funding Amount
$392,090.00
Summary
Marrow and microenvironmental cell (MC) interactions play a central role in bone marrow (BM) cell localisation and regulation. Specifically, the regulation of primitive blood cells (HSC) is affected by their locality and their expression of a wide repertoire of cell adhesion molecules (CAM). This project is based upon the unique observation made in the applicants laboratory demonstrating that both murine HSC and candidate human HSC synthesize the carbohydrate CAM hyaluronic acid (HA). Moreover w ....Marrow and microenvironmental cell (MC) interactions play a central role in bone marrow (BM) cell localisation and regulation. Specifically, the regulation of primitive blood cells (HSC) is affected by their locality and their expression of a wide repertoire of cell adhesion molecules (CAM). This project is based upon the unique observation made in the applicants laboratory demonstrating that both murine HSC and candidate human HSC synthesize the carbohydrate CAM hyaluronic acid (HA). Moreover we have now accumulated data suggesting a key role for HA in determining the spatial distribution of HSC within the BM following transplantation and in regulating their development into mature blood cells. Encapsulating the concept of highly specific, local interactions regulating blood cells is the 'niche' hypothesis in which MC form a specific 'niche'. The current inability to identify HSCs in situ makes it impossible to analyse either their distribution or molecules that regulate this process. Circumstantial evidence suggests the presence of HSC niches in close association with the bone. Using a novel approach based on BM transplantation to track cells lodging in the BM, we were the first to report that the lodgment of a transplant of HSC is not a random process, but results in cells of donor origin being located at the bone-marrow interface. The presence of HA on HSC was critical for this pattern of lodgment. In addition, we have also accumulated evidence suggesting that HA is important in the maintenance of HSC in their primitive state. This proposal aims to confirm the critical role of HA in HSC biology.Read moreRead less
The Developmental Hierarchy Of Haemopoietic Lineage Relationships
Funder
National Health and Medical Research Council
Funding Amount
$192,000.00
Summary
The blood cells are all the progeny of a very rare stem cell, that is thought to reside in the bone marrow. The stem cell maintains itself throughout the life span of the individual as well as generating the billions of more mature cell types required in the blood. However the processes and stages that immature cells pass through from the stem cell to ultimately a mature functional blood cell such as a lymphocyte remain disputed. This study aims to determine to relationship of the various blood ....The blood cells are all the progeny of a very rare stem cell, that is thought to reside in the bone marrow. The stem cell maintains itself throughout the life span of the individual as well as generating the billions of more mature cell types required in the blood. However the processes and stages that immature cells pass through from the stem cell to ultimately a mature functional blood cell such as a lymphocyte remain disputed. This study aims to determine to relationship of the various blood cell progeny with each other and thus to provide a lineage map of the system. To do this we will isolate precursors at various stages along the developmental pathways and determine their capabilities to produce the normal range of progeny. We will then use a number of genetically altered mouse strains to assess the genes involved in this process. These studies will help provide an underlying scientific basis to the attempts to development a number of stem cell therapies that are aimed at boosting or directing stem cell production in procedures such as bone marrow transplantation for leukemia and immune deficiency. In addition a number of characterized human blood malignancies seem to have developed along aberrant pathways indicating that inappropriate lineage specification may be a factor in cancer.Read moreRead less
Role Of Neutrophil Proteases In The Mobilisation Of Haemopoietic Progenitor Cells
Funder
National Health and Medical Research Council
Funding Amount
$318,279.00
Summary
Mobilisation is a procedure consisting in inducing the egress of blood forming cells (haemopoietic stem cells) from the bone marrow, where they normally reside, into the blood. The most common agent to induce mobilisation of haemopoietic stem cell is a cytokine called granulocyte - colony stimulating factor (G-CSF). In recent years, the number of transplantations performed with mobilised blood stem cells has exceeded those performed with bone marrow. Elements contributing to this success have be ....Mobilisation is a procedure consisting in inducing the egress of blood forming cells (haemopoietic stem cells) from the bone marrow, where they normally reside, into the blood. The most common agent to induce mobilisation of haemopoietic stem cell is a cytokine called granulocyte - colony stimulating factor (G-CSF). In recent years, the number of transplantations performed with mobilised blood stem cells has exceeded those performed with bone marrow. Elements contributing to this success have been the simplicity of the procedure (daily injections of a mobilising cytokines such as G-CSF), a more rapid recovery following high dose chemotherapy and transplantation, and lower costs. Despite its common use in clinics, the molecular mechanisms responsible for haemopoietic stem mobilisation following injection of cytokines are still unknown. A large body of experimental data demonstrate the critical role of adhesive interactions between blood forming cells and the bone marrow microenvironment These interactions control the lodgement of blood forming cells in the bone marrow, where they normally reside, and their egress into the blood during mobilisation. Experiments from this laboratory have shown that the mobilisation of blood forming cells that follows the administration of G-CSF, may be the consequence of the accumulation in the bone marrow of a class of leukocytes called neutrophils. These neutrophils subsequently release within the bone marrow a set of enzymes that specifically cleave a cell adhesion molecule expressed in the bone marrow, and therefore disrupt the adhesive interactions between the bone marrow and the blood forming cells resulting in their egress in the blood. This proposal aims to demonstrate this hypothesis and to provide tools to predict and improve the levels of mobilisation that can be achieved with healthy donors and cancer patients.Read moreRead less