Lecture 10

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Questions and Answers

What is the primary purpose of the fluorochrome in the HSC separation process?

To label HSCs with a visible marker. (correct)

To make the capillary more visible under the microscope.

To kill and remove unwanted cells in the sample.

To separate cells based on size.

During bone marrow extraction for HSC collection, approximately how much bone marrow is typically collected from the donor?

100 milliliters.

1 liter. (correct)

2 liters.

500 milliliters.

What are limbal stem cells, also known as corneal epithelial stem cells, primarily used for treating?

Heart conditions.

Spinal cord injuries.

Skin burns.

Corneal injuries. (correct)

Which of the following is NOT a typical source of mesenchymal stem cells (MSCs)?

Corneal limbus. (B) Signup and view all the answers

What is the initial step in obtaining MSCs from adipose tissue?

Collection by liposuction. (C) Signup and view all the answers

What is the primary process involved in generating induced pluripotent stem cells (iPSCs)?

Reprogramming of cell nuclei. (B) Signup and view all the answers

Which of the following is a characteristic feature of induced pluripotent stem cells (iPSCs)?

Expression of specific proteins like c-kit and Thyl. (D) Signup and view all the answers

Which research area primarily uses iPSCs for studying disease mechanisms?

Disease etiology. (A) Signup and view all the answers

Which of the following is considered a potential clinical application of stem cells?

Treating myocardial infarction (heart attack). (D) Signup and view all the answers

Apart from bone marrow, where else can MSCs be found?

Adipose tissue. (B) Signup and view all the answers

What is the purpose of passaging in the context of embryonic stem cell (ESC) culture?

To obtain a homogeneous group of ESCs with pluripotent properties. (D) Signup and view all the answers

Which factor is crucial for maintaining the pluripotency of embryonic stem cells in culture?

Leukemia inhibitory factor (LIF). (D) Signup and view all the answers

Why are there currently no approved therapeutic uses of human embryonic stem cells (ESCs)?

The ethical concerns, alongside the difficulties in culturing and directing ESCs, prevent therapeutic use. (A) Signup and view all the answers

What is a primary advantage of using umbilical cord blood as a source of fetal stem cells?

It has a low risk of disease transmission and transplant rejection. (A) Signup and view all the answers

A primary clinical drawback of using umbilical cord blood is:

Delayed hematological renewal in the recipient's marrow. (D) Signup and view all the answers

What is the primary method used to obtain hematopoietic stem cells (HSCs) for therapeutic applications?

Apheresis using peripheral blood. (C) Signup and view all the answers

What is the role of G-CSF in the mobilization of hematopoietic stem cells (HSCs)?

Stimulating the release of HSCs from the bone marrow into the blood. (B) Signup and view all the answers

What is the primary purpose of using fluorophore-labeled antibodies in HSC separation?

To allow identification and separation of HSCs using fluorescent light. (B) Signup and view all the answers

During HSC separation, what specific protein on the surface of HSCs is targeted by antibodies for identification?

CD34 protein. (B) Signup and view all the answers

What percentage of cells in a blood cell suspension are typically HSCs after separation?

5 to 20% of total cells. (A) Signup and view all the answers

What is the primary characteristic that distinguishes stem cells from other cell types?

Their ability to differentiate into various cell types and self-renew. (A) Signup and view all the answers

Which of the following best describes asymmetric cell division in stem cells?

One daughter cell remains a stem cell, whilst the other becomes a partially differentiated precursor cell. (B) Signup and view all the answers

What is the differentiating factor between totipotent and pluripotent stem cells?

Totipotent stem cells can form all cell types including extra-embryonic structures. (D) Signup and view all the answers

Which classification of stem cells can differentiate into all cell types, but only within a specific germ layer?

Multipotent (C) Signup and view all the answers

Where do somatic stem cells primarily reside in the body?

In specific areas, called niches, between differentiated cells. (C) Signup and view all the answers

What role do stem-cell niches play in the body?

To provide a specific microenvironment that supports the function of stem cells. (C) Signup and view all the answers

How do somatic stem cells typically behave when an organ is damaged?

They activate, divide and become the specialized cells needed for tissue repair. (D) Signup and view all the answers

Which of these is NOT a location where hematopoietic stem cells (HSCs) are found?

Intestines (A) Signup and view all the answers

What type of cells do hemopoietic precursor cells give rise to?

Erythrocytes, leukocytes, and thrombocytes (C) Signup and view all the answers

Which of the following best describes the function of mesenchymal stem cells (MSCs)?

They are multipotent cells found in various tissues, including bone marrow, adipose tissue and others. (C) Signup and view all the answers

Where are epidermal stem cells primarily located in the skin?

In the basal layer of the epidermis. (D) Signup and view all the answers

Which cell type is responsible for the regeneration of hair and sebum glands?

Hair follicle stem cells (B) Signup and view all the answers

In which part of the small intestine are intestinal stem cells found?

The crypts (A) Signup and view all the answers

Satellite cells are a type of somatic stem cell specific to which tissue?

Skeletal muscle (C) Signup and view all the answers

What is the main characteristic of very small embryonic-like stem cells (VSELs)?

They are smaller than erythrocytes and have a large nucleus. (D) Signup and view all the answers

What is the primary role of limbal stem cells in the eye?

Producing new corneal cells (B) Signup and view all the answers

Which procedure is involved in obtaining MSCs from adipose tissue?

Liposuction for collection (D) Signup and view all the answers

What distinguishes induced pluripotent stem cells (iPSCs) from other stem cell types?

They are derived from non-pluripotent somatic cells. (A) Signup and view all the answers

Which type of stem cells are capable of differentiating into all cell types including sex cells and extra-embryonic structures?

Totipotent (C) Signup and view all the answers

What is a primary therapeutic application of MSCs?

Healing skin burns and diabetic foot (B) Signup and view all the answers

What is one benefit of using iPSCs in research?

They can be used to study gene expression and disease mechanisms. (D) Signup and view all the answers

What is the primary role of embryonic stem cells derived from blastocysts?

Differentiating into any type of cell in the body (C) Signup and view all the answers

Which statement about the population of MSCs in adipose tissue is true?

They are less variable and more homogeneous than bone marrow MSCs. (B) Signup and view all the answers

Which stem cell type is primarily found in adult tissues and can only differentiate into one specific cell type?

Unipotent stem cells (D) Signup and view all the answers

During the bone marrow extraction procedure for HSC collection, what key aspect is ensured for the donor?

The donor must remain hospitalized for monitoring. (A) Signup and view all the answers

What characteristic is most associated with somatic stem cells (SSCs) as they age?

Decrease in the number present (A) Signup and view all the answers

Which type of injuries can benefit from the transplantation of limbal stem cells?

Corneal injuries (D) Signup and view all the answers

Which of the following best describes the distinction between symmetric and asymmetric division in stem cells?

Both divisions yield only stem cells in symmetric division, while asymmetric yields one stem and one differentiated cell. (D) Signup and view all the answers

What is a potential application for stem cells in clinical scenarios?

Treatment of spinal cord injuries (D) Signup and view all the answers

What is the primary function of the hematopoietic stem cell (HSC) niche?

To provide a microenvironment necessary for HSC survival and regulation (A) Signup and view all the answers

Where are mesenchymal stem cells (MSCs) primarily located?

In various tissues including adipose and bone marrow (D) Signup and view all the answers

Which stem cell type is considered a transitional form between embryonic stem cells and differentiated somatic cells?

Fetal stem cells (C) Signup and view all the answers

What is a unique feature of very small embryonic-like stem cells (VSELs)?

They have a high nuclear-to-cytoplasmic ratio. (A) Signup and view all the answers

Which type of stem cell is exclusively located in the epidermis and responsible for the regeneration of skin layers?

Epidermal stem cells (B) Signup and view all the answers

Which of the following stem cell types is known for their role in muscle tissue regeneration and growth?

Skeletal muscle somatic stem cells (B) Signup and view all the answers

What is the main limitation associated with pluripotent stem cells?

They cannot revert to totipotency once differentiated. (A) Signup and view all the answers

What type of signaling substances are critical within a stem-cell niche?

Hormonal and neuronal signals, along with immune cell messages (D) Signup and view all the answers

Which property is NOT typical of stem cells?

High metabolic activity (D) Signup and view all the answers

What is the primary reason for the lack of approved therapeutic uses for human embryonic stem cells (ESCs)?

Ethical controversies surrounding the use of embryos (D) Signup and view all the answers

Which step is involved in the pre-collection preparation of hematopoietic stem cells (HSCs) from peripheral blood?

Administration of corticosteroids and G-CSF (A) Signup and view all the answers

What is a significant clinical drawback of using umbilical cord blood as a source of stem cells?

Lower number of hematopoietic stem cells compared to bone marrow (B) Signup and view all the answers

What is the main role of leukemia inhibitory factor (LIF) in culturing embryonic stem cells (ESCs)?

Prevents loss of pluripotency in ESCs (A) Signup and view all the answers

During the HSC separation process, what is the function of fluorophores attached to antibodies?

To specifically mark HSCs for laser separation (A) Signup and view all the answers

Which factor contributes to the clinical advantage of using umbilical cord blood as a source of fetal stem cells?

Low risk of graft-versus-host disease (A) Signup and view all the answers

What happens during the mobilization stage prior to HSC collection through apheresis?

Medications are administered to stimulate the release of HSCs (C) Signup and view all the answers

Which of the following describes a limitation of hematopoietic stem cells (HSCs) collected from peripheral blood?

They may lead to delayed hematological renewal in recipients (D) Signup and view all the answers

What is the aim of passaging embryonic stem cells (ESCs)?

To maintain a homogeneous population of cells (D) Signup and view all the answers

What is one of the key challenges in directing embryonic stem cells (ESCs) to differentiate into specific tissues?

Achieving functional integration in the host (D) Signup and view all the answers

Study Notes

Stem Cells

Stem cells are found in the human body from the embryonic stage through adulthood.
Stem cells are undifferentiated cells that have not yet become a specific cell type.
All stem cells have two key properties: unlimited capacity for division and the ability to differentiate into various body cell types.
Stem cells have specific morphological features, including a large nucleus and a narrow rim of cytoplasm.
Stem cells divide in two ways: symmetric (both daughter cells retain stem cell properties) and asymmetric (one daughter retains stem cell properties; the other is partially differentiated).
The potential for differentiation (potency) distinguishes different stem cells (totipotent, pluripotent, multipotent, unipotent).

Stem Cell Classification

Stem cells are classified based on their potential for differentiation (potency) and source of origin.
Totipotent/omnipotent stem cells have the potential to differentiate into all cell types, including sex cells and extra-embryonic tissue (e.g. placenta, zygote, blastula cells).
Pluripotent stem cells can differentiate into all cell types in the body, except sex cells and extra-embryonic tissue.
Multipotent stem cells can differentiate into various cell types, but only within a certain germ layer (ectoderm, endoderm, or mesoderm).
Unipotent stem cells can only differentiate into one type of specialized cell.
Stem cells are also classified based on their source of origin, such as embryonic, fetal, or somatic stem cells.

Types of Stem Cells

Embryonic stem cells (ESCs) originate from the inner cell mass of blastocysts, which are at the 4-8 cell stage.
Fetal stem cells (FSCs) are found in fetal tissues (blood, liver, etc.) and extra-embryonic tissues (placenta, amniotic fluid).
Somatic stem cells (SSCs) are found in adult organs and tissues (bone marrow, skin, etc.), can be multipotent or unipotent.

Stem Cell Niches

Stem-cell niches provide a specialized microenvironment for stem cell maintenance and regulation.
Niches are composed of extracellular matrix proteins, structural elements and signalling substances, mature cells (e.g., osteoblasts, macrophages, endothelial cells), immune cells, oxygen, nutrients, and hormones.
HSC niches for hematopoietic stem cells are located in the bone marrow near endosteal and vascular compartments. Different stem cells rely on different niches.
MSC niches associated with mesenchymal stem cells are present in bone marrow, adipose tissue, periosteum, skeletal muscle, skin, bones, lungs, and periodontal ligaments/dental pulp.
Skin SSC niches include epidermal stem cells, hair follicle stem cells, and melanocyte stem cells.

Obtaining Stem Cells

Animal embryonic stem cells were obtained from mouse embryos (1981), rhesus embryos (1995), and rat embryos (2008).
Human embryonic stem cells were isolated in 1998.
Obtaining ESCs involves placing blastocysts in a petri dish with a layer of fibroblasts, and the resulting embryonic cells spreading to form colonies
Isolating homogenous ESCs requires multiple passages and a specific culture media

HSC Separation

HSC separation is performed using apheresis.
The procedure involves isolating blood cells using antibodies combined with fluorescent dyes to specifically target HSCs. Then, a laser separates the fluoresced cells from other components.
The next method uses a biopsy needle to collect bone marrow.

Therapeutic Application of Stem Cells

Hematopoietic stem cells are used in treating non-solid tumors (e.g., leukemia, lymphomas) and non-cancer diseases (e.g., anemia, immune disorders).
Somatic stem cells are for treating corneal injuries, helping repair damaged cornea.
Mesenchymal stem cells are used in treating various conditions, including skin burns, trophic ulcers, and diabetic foot.
Induced pluripotent stem cells have potential applications in disease modeling, drug screening, and tissue regeneration.

Potential Clinical Applications

Stem cells have potential applications in treating myocardio infarction, stroke, parkinsonism, spinal cord injury, diabetes, myopathy, and liver injury.

Very Small Embryonic-like Stem Cells (VSELs)

VSELs are remnants of embryonic tissue found throughout adult tissues (small numbers).
VSELs are morphologically distinctive (larger nuclei, high nuclear to cytoplasm ratio, undifferentiated chromatin). They also have epigenetic marks like histone methylation.

Umbilical Cord Blood

Umbilical cord blood is a source of fetal stem cells, with advantages like rapid availability, short waiting times, and lower risk of rejection.
However, it has some drawbacks, including lower hematopoietic stem cell numbers and a risk of genetic disease transmission.

Induced Pluripotent Stem Cells (iPSCs)

iPSCs are stem cells artificially derived from non-pluripotent somatic cells. The process involves reprogramming the cell's nuclear to change gene expression of a mature somatic cell to a stem cell.
iPSCs have features like large nuclei, less cytoplasm, ability to divide and self-renew and specific proteins.
iPSCs are used for research into disease etiology, embryogenesis, abnormal development, gene action, drug testing, and potential clinical applications.

Other Notable Points:

Ethical Concerns: Obtaining embryonic stem cells raises ethical concerns regarding the use of embryos.
Homogeneity: Adipose tissue is a better source of MSCs than bone marrow, as the MSC population is more homogeneous.

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Description

This quiz explores the fascinating world of stem cells, including their properties, functions, and classification based on differentiation potential. Understand the key characteristics that distinguish stem cells and the different types based on their origin and potency. Test your knowledge on how stem cells contribute to human development and medicine.