Periodic Reporting for period 2 - IC-CCD-qHSC (Intrapopulation communication and collective cell decisions of hematopoietic stem cells)
Periodo di rendicontazione: 2022-04-01 al 2023-09-30
Hematopoietic stem cells sustain the continuous generation of mature blood cells throughout life. HSCs have the capacity to differentiate into any hematopoietic lineage (termed multipotency), while generating copies of themselves to preserve a relatively constant size of the HSC pool. Notably, ample evidence demonstrates that the preservation of these key properties of HSCs and their maintenance is tightly regulated by the native tissue microenvironment of bone marrow (BM) in which they reside. Albeit some of the cellular components and molecular cues participating in the control of HSC function in their anatomical niche have been described to date, a major unanswered question is how individual HSCs coordinate proliferation and differentiation to collectively maintain the homeostatic numbers in the BM. The fundamental goal of this project is to uncover the potential mechanisms underlying this collective behavior. For this we have mapped the distribution of HSCs throughout postnatal development, into adulthood and ageing and analyzed the presence of regions in which HSCs accumulate at highest densities. Our underlying hypothesis is that direct or indirect exchange of signals within such regions provide information of the state of the population and synchronize their behaviors towards the collective maintenance of the HSC population. Understanding how somatic stem cells are regulated and participate in organ homeostasis and repair is fundamental to harness the therapeutic potential of these crucial cellular subsets.Hematopoietic stem cells sustain the continuous generation of mature blood cells throughout life. HSCs have the capacity to differentiate into any hematopoietic lineage (termed multipotency), while generating copies of themselves to preserve a relatively constant size of the HSC pool (self-renewal). Notably, ample evidence demonstrates that the preservation of these key properties of HSCs and their maintenance is tightly regulated by the native tissue microenvironment of bone marrow (BM) in which they reside. Albeit multiple cellular components and molecular cues participating in the control of HSC function in their anatomical niches have been described to date, a major unanswered question is how individual HSCs coordinate proliferation and differentiation to collectively maintain the homeostatic numbers in the BM. The fundamental goal of this project is to uncover the potential mechanisms underlying this collective behavior. For this we have mapped the distribution of HSCs throughout postnatal development, into adulthood and ageing and analyzed the presence of regions in which HSCs accumulate at highest densities. Our underlying hypothesis is that direct or indirect exchange of signals within such zones provides information of the state of the population to individual HSCs and synchronizes their behavior towards the collective maintenance of the HSC population. Understanding how somatic stem cells are regulated and participate in organ homeostasis and repair is fundamental to harness the therapeutic potential of these crucial cellular subsets.
The main areas of development of the experimental work described in the proposal are highlighted below:
- We have performed a detailed longitudinal mapping of the localization of HSCs in BM tissues throughout postnatal development, as well as in adulthood and ageing and analyzed their interactions via 3D quantitative imaging or marrow tissues. We have additionally characterized the composition of all progenitor cell subsets and the proliferative behavior of HSCs at all stages.
- Mouse strains carrying multiple transgenes in which the expression of various molecular cues, which are hypothesized to be involved in the communication between HSCs can be targeted have been generated and validated in the lab during this time.
- We have recently developed new computational tools for the automated segmentation of blood vessels, tissue boundaries and the detection of cells of interest in 3D imaging datasets using deep learning and convolutional neural networks.
- The analysis of the spatial distribution and properties of HSCs described above has been complemented by the in depth characterization of stromal cell composition across postnatal development using single cell RNA sequencing and spatial mapping in BM images
- We have generated and analyzed mouse strains in which expression of the gene for Insulin growth factor 2 is suppressed in different cell types.
- We have performed a detailed longitudinal mapping of the localization of HSCs in BM tissues throughout postnatal development, as well as in adulthood and ageing and analyzed their interactions via 3D quantitative imaging or marrow tissues. We have additionally characterized the composition of all progenitor cell subsets and the proliferative behavior of HSCs at all stages.
- Mouse strains carrying multiple transgenes in which the expression of various molecular cues, which are hypothesized to be involved in the communication between HSCs can be targeted have been generated and validated in the lab during this time.
- We have recently developed new computational tools for the automated segmentation of blood vessels, tissue boundaries and the detection of cells of interest in 3D imaging datasets using deep learning and convolutional neural networks.
- The analysis of the spatial distribution and properties of HSCs described above has been complemented by the in depth characterization of stromal cell composition across postnatal development using single cell RNA sequencing and spatial mapping in BM images
- We have generated and analyzed mouse strains in which expression of the gene for Insulin growth factor 2 is suppressed in different cell types.
Our project is geared towards uncovering core principles governing the collective behavior of HSCs. During these initial phases of the project we have made major advances in the experimental work, and our preliminary results are promising and suggest that HSCs spatially associate in clusters, and coordinate their behaviors during development and in response to stress . Nonetheless, at this stage of the project, the data obtained does not allow us to draw solid, robust conclusions and our principal hypotheses have not yet been confirmed. We anticipate that the experimental tools generated and optimized during these initial phases of the project will be instrumental in allowing us to reach the fundamental aims of the project in the expected timeframe.