Name: how hsc signals control blood cell supply
Uploaded: 2023-04-30T10:37:43.000Z
Duration: 1 min 1 s
Channel: JoVE

Colony-stimulating factors or CSFs are glycoproteins that bind to receptors on hematopoietic stem cells or HSCs to regulate their growth and differentiation.
CSFs circulate in the blood and bone marrow as soluble factors. Stromal cells also secrete membrane-bound CSFs called stem cell factors to keep quiescent &#160;HSCs inactive and maintain the stem cell pool.
As active HSCs divide and differentiate into committed progenitors, CSFs stimulate the progenitors to proliferate and differentiate to form colonies of specific blood cell types.
Upon microbial infection, CSFs induce progenitors to produce immune cells that are released into the bloodstream to attack the invading microbes.
In the absence of CSFs, the immune cells undergo apoptosis, preventing the cancerous growth of blood cells.

regulation of hematopoietic stem cells

Regulation of Hematopoietic Stem Cells

All blood and immune cells are produced from the multipotent hematopoietic stem cells (HSCs) by the process of hematopoiesis. However, they all have a limited life span. In addition, many are depleted in immune surveillance or combatting an injury or infection. This makes blood one of the most regenerative tissues. Hematopoiesis helps replenish these blood and immune cells, restoring the body&#39;s normal functioning. However, overproduction of blood and immune cells can make them cancerous or activate autoimmune responses. Thus, hematopoiesis needs to be a tightly regulated process.
Regulation of hematopoiesis helps determine whether the HSCs stay quiescent or undergo any other fate such as self-renewal, differentiation, or apoptosis. Several soluble or membrane-bound factors such as cytokines or colony-stimulating factors (CSFs) regulate hematopoiesis.&#160; For example, stem cell factors or steel produced by the bone marrow stroma make contact with c-kit receptors on quiescent HSCs, providing them with survival signals and HSC maintenance. The CSFs are inflammatory cytokines produced by fibroblasts and macrophages in response to allergies and bacterial or parasitic infections. CSFs regulate the rate of HSC proliferation and the number of cell division cycles they must undergo before differentiating into progenitor cells. This ensures the human body possesses an adequate reserve of stem cells to maintain all blood cell types.&#160; CSFs also induce the progenitors to commit to lineage-specific blood and immune cells and perform their functions. They assist with rapid differentiation into specific immune cells and elicit an immediate immune response until the infection is cleared. In the absence of CSFs, HSCs undergo apoptosis.

All blood and immune cells are produced from the multipotent hematopoietic stem cells (HSCs) by the process of hematopoiesis. However, they all have a ...

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JoVE Core

Cell Biology

Unit 1

A Hierarchical Stem-Cell System: Blood Cell Formation

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KEY TERMS AND CONCEPTS

how hsc signals control blood cell supply

Hematopoietic stem cells, or HSCs, make blood and immune cells through hematopoiesis. These cells are replaced often because many have short life spans. They are also used up during immune surveillance, injury, or infection. This makes blood one of the most regenerative tissues in the body.

Hematopoiesis must stay tightly controlled. If too many blood or immune cells are made, the cells can become cancerous or trigger autoimmune responses. Regulation helps HSCs stay quiescent, which means inactive, or move into self-renewal, differentiation, or apoptosis, which is programmed cell death. These choices keep the stem cell pool balanced.

Several cytokines and colony-stimulating factors, or CSFs, help control this process. One example is stem cell factor, also called steel, which is made by the bone marrow stroma. It binds to c-kit receptors on quiescent HSCs and gives them survival signals. This helps maintain HSCs in the bone marrow.

CSFs are inflammatory cytokines made by fibroblasts and macrophages. They are released in response to allergies and bacterial or parasitic infections. CSFs control how fast HSCs divide and how many divisions they complete before becoming progenitor cells. This helps keep enough stem cells available to support all blood cell types.

CSFs also push progenitor cells to commit to specific blood and immune lineages. This supports rapid differentiation into the cells needed for defense. The new immune cells can then act right away until the infection is cleared. Without CSFs, HSCs undergo apoptosis.

How HSC Signals Control Blood Cell Supply

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How new blood vessels grow through angiogenesis is a key part of early development and tissue repair. Blood vessel formation begins around day 7 of embryonic development. In the extraembryonic yolk sac, mesodermal precursor cells called hemangioblasts multiply and become angioblasts. Angioblasts express vascular endothelial growth factor receptor 2, or VEGFR2. This receptor binds VEGF-A, a proangiogenic factor that helps guide vessel formation. VEGF signaling pushes angioblasts to form a blood...

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hematopoiesis

Blood Cell Formation and Stem Cell Migration

Blood cell formation, or hematopoiesis, begins early in development. Around the seventh day of embryogenesis, the primitive wave starts in the extraembryonic yolk sac. In this early stage, a common precursor called a hemangioblast gives rise to erythroid cells and endothelial cells. The erythroid cells help carry oxygen and support the fast growth of the embryo. Hemangioblasts later develop into hematopoietic stem cells, or HSCs. These stem cells are multipotent, which means they can produce...

multipotency of hematopoietic stem cells

HSC Quiescence and Blood Cell Renewal

Hematopoietic stem cells (HSCs) help the body make blood and immune cells. These stem cells are multipotent, which means they can develop into many cell types in the blood system. They usually stay in a quiescent, or resting, state until an outside signal starts them moving toward differentiation. HSCs are grouped into two main populations: long-term repopulating cells (LTRCs) and short-term repopulating cells (STRCs). These groups differ in surface markers, or receptors on the cell surface,...

lineage commitment

Blood Stem Cell Fate Decisions

Blood stem cell fate decisions guide how hematopoietic stem cells become specific blood and immune cells. During commitment, stem cells lose the ability to form all cell types and change irreversibly into a more limited fate. Multipotent hematopoietic stem cells, or HSCs, first differentiate into multipotent hematopoietic progenitor cells, or HPCs. These HPCs express many lineage-specific cytokine receptors. Each receptor binds a specific cytokine, turns on a distinct signaling pathway, and...

erythropoiesis

How Red Blood Cells Are Replenished

Red blood cells, or RBCs, carry oxygen to body tissues and must be replaced after about 120 days. The body keeps this supply steady through erythropoiesis, the process of making new red blood cells. When oxygen levels drop after blood loss or injury, this process increases to restore oxygen delivery. Problems in erythropoiesis can lead to anemia, thalassemia, or polycythemia. Erythropoietin, also called Epo, starts this process. Before birth, the fetal liver makes Epo. After birth,...

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CSF Signals That Guide Myeloid Cells

Common myeloid progenitors are blood-forming cells in the bone marrow that can become granulocytes or macrophages. These immune cells protect the body against bacterial, viral, and fungal infections. They leave the bone marrow, travel in the blood, and move into tissues where they help with immune surveillance. These cells do not last long. They survive for only a few days, so the body must keep making them to maintain a strong immune system. During injury or infection, many immune cells are...

Hematopoietic stem cells, or HSCs, make blood and immune cells through hematopoiesis. These cells are replaced often because many have short life spans. They are also used up during immune surveillance, injury, or infection. This makes blood one of the most regenerative tissues in the body. Hematopoiesis must stay tightly controlled. If too many blood or immune cells are made, the cells can become cancerous or trigger autoimmune responses. Regulation helps HSCs stay quiescent, which means...

key terms and concepts

Learn how cytokines and colony-stimulating factors guide hematopoietic stem cells to stay quiet, divide, or become blood and immune cells.

How HSC Signals Control Blood Cell Supply | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

How HSC Signals Control Blood Cell Supply

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