Name: hsc quiescence and blood cell renewal
Uploaded: 2023-04-30T10:37:13.000Z
Duration: 1 min 19 s
Channel: JoVE

Hematopoietic stem cells&#160; or HSCs are multipotent, meaning they can form all types of blood cells.
In an embryo, hematopoiesis occurs in the liver, where an HSC divides symmetrically, producing two daughter cells. These HSCs continue to multiply by self-renewal.
Under the influence of growth factors called cytokines, the HSCs differentiate into progenitors of blood cells.
In adults, HSCs reside in the bone marrow and interact with the surrounding stromal cells .
Receptor-ligand interaction brings the HSC and the stromal cells together.&#160; Such cell-cell contact inhibits HSC proliferation as they enter the G0 state of the cell cycle and become non-dividing or quiescent.
Upon tissue injury, vascular endothelium releases growth factors that allow the quiescent HSCs to lose contact with the surrounding stroma and migrate to the blood vessels.
HSCs now undergo asymmetric division, maintaining the HSC pool and forming committed progenitors that differentiate into mature blood cells.

multipotency of hematopoietic stem cells

Multipotency of Hematopoietic Stem Cells

The hematopoietic stem cells or HSCs are multipotent, meaning they can differentiate and give rise to all blood and immune cells. HSCs are maintained in the quiescent stage until an external stimulus initiates their differentiation. The multipotent HSCs exist as two heterogeneous populations, long-term repopulating cells (LTRC) and short-term repopulating cells (STRC). The two HSC populations have different surface markers or receptors and are classified based on quiescence and long-term renewal capacity.
The long-term HSCs rarely divide as they maintain long gaps between successive cell divisions while keeping their metabolic activity to the bare minimum. Thus, the LTRCs undergo a few rounds of symmetric cell divisions before entering the state of dormancy. This allows them to expand the number of HSCs and maintain a stem cell pool before exhausting their regenerative and self-renewal potential.
LTRCs produce the more active multipotent short-term repopulating cells (STRC) in response to external stimuli. STRCs undergo fewer self-renewal divisions than the LTRCs and differentiate into specific blood or immune cells. LTRCs and STRCs find application in engraftment and therapeutic studies. The LTRCs can sustain hematopoiesis for upto four months upon transplantation into the recipients, while transplantation of STRCs supports hematopoiesis for only a few weeks. A delicate balance between dormancy and differentiation stimuli maintains the HSC population for the long run. A slow or non-responsive quiescent HSCs leave the body devoid of differentiated blood cells such as erythrocytes, phagocytes, and lymphocytes which are necessary for transporting nutrients or providing immune surveillance. In contrast, highly active HSCs exhaust the stem cell population making them unavailable to renew, repair, or replace blood cells lost due to an injury or infection.

The hematopoietic stem cells or HSCs are multipotent, meaning they can differentiate and give rise to all blood and immune cells. HSCs are maintained in ...

Education

JoVE Core

Cell Biology

Unit 1

A Hierarchical Stem-Cell System: Blood Cell Formation

a-hierarchical-stem-cell-system-blood-cell-formation

KEY TERMS AND CONCEPTS

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, and in how long they can keep renewing themselves. LTRCs divide rarely and keep their metabolic activity very low. STRCs are more active and are closer to becoming specific blood or immune cells.

LTRCs can go through a few rounds of symmetric cell division before entering dormancy again. This helps increase the HSC pool without using up the stem cells too quickly. In response to external stimuli, LTRCs can produce STRCs. STRCs then carry out fewer self-renewal divisions and move on to form specific blood or immune cells.

These two HSC populations are important in engraftment and therapeutic studies. After transplantation, LTRCs can support hematopoiesis, or blood cell formation, for up to four months in a recipient. STRCs support hematopoiesis for only a few weeks.

A balance between dormancy and differentiation keeps the HSC pool working over time. If quiescent HSCs do not respond enough, the body can be left without enough erythrocytes, phagocytes, and lymphocytes. If HSCs become too active, the stem cell pool can be exhausted and lose its ability to renew, repair, or replace blood cells after injury or infection.

HSC Quiescence and Blood Cell Renewal

overview of the vascular system

Blood and Lymphatic Vessel Layers

The vascular system includes blood vessels and lymphatic vessels. It forms a large network of arteries, capillaries, and veins. In the body, this system is divided into the blood system and the lymphatic system. Blood vessels have three main histological layers. These layers are the tunica intima, tunica media, and tunica adventitia. The tunica intima is the inner layer. It has a single layer of endothelial cells attached to the basal lamina. Beneath that is a connective tissue layer and an...

mechanism of angiogenesis

How New Blood Vessels Grow

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...

regulation of angiogenesis and blood supply

regulation-of-angiogenesis-and-blood-supply

Hypoxia Triggers Angiogenesis Signaling

Hypoxia, or low oxygen, can trigger angiogenesis signaling in tissues that need more blood supply. Rapidly dividing tumors, embryos, and wounded tissues all use more oxygen than usual. As oxygen levels fall, cells switch on a pathway that helps form new blood vessels. A key oxygen sensor in this pathway is hypoxia-inducible factor 1, or HIF1. HIF1 has two parts, an alpha subunit and a beta subunit. Under normal oxygen conditions, HIF1 beta is in the nucleus, while HIF1 alpha stays in the...

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...

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,...

differentiation of common myeloid progenitor cells

differentiation-of-common-myeloid-progenitor-cells

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...

regulation of hematopoietic stem cells

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...

key terms and concepts

Learn how hematopoietic stem cells stay quiescent, form long-term and short-term repopulating cells, and support blood and immune cell renewal.

HSC Quiescence and Blood Cell Renewal | 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.

HSC Quiescence and Blood Cell Renewal

Description

Transcript

Tags