Stem Cell Basics
Stem Cells: What is it and how it works

What Are Stem Cells? And How Do They Work?

A stem cell is a special type of cell that can develop into a wide range of other types of cells, from muscle cells to brain cells. Stem cells can also “repair” damaged cells and tissue. Today, the National Institutes of Health from around the world are even researching the possibility of curing paralysis and Alzheimer’s using stem cell therapy.

What are stem cells?

Stem cells are the progenitor cells of every cell and tissue of the human body. One of its main features is the ability to self-renew and grow. Stem cells are unique because they can also develop into each of more than 200 cell types: blood cells (white and red blood cell types, as well as the endothelium), heart tissue, skin, muscles, brain cells, and more.

Scientists have received many positive results from using stem cell preparations in the treatment of multiple sclerosis, Crohn’s disease, Parkinson’s disease, heart failure, rheumatoid arthritis, leukemia, and various types of malignant tumors.

History of stem cells

  • The term “stem cell” was first implemented in 1908 by A.A. Maksimov, a Russian histologist.
  • The first bone marrow transplant was carried out for identical twins in 1959 by Donnal Thomas.
  • Soon after, the presence of umbilical blood stem cells was confirmed by many researchers. In 1988, Elean Gluckman, a professor of hematology in Paris, performed the world’s first umbilical blood transplant for a child with Fanconi anemia.
  • A year later, in the United States, the first public umbilical blood banking program was launched, providing free umbilical blood transplants to patients with positive indications for stem cell transplantation.

Importance of stem cells

When we get injured or sick, our cells become wholly or partially damaged. When this happens, stem cells activate and repair damaged tissues, replacing old and dying cells. Thus, stem cells can both support our health and prevent premature aging.

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Types of stem cells

There are many different types of stem cells. Scientists believe that each organ in our body has a specific type of stem cells. For example, our blood comes from blood stem cells (also known as hematopoietic stem cells). Depending on the source, the basic types of stem cells are:

1. Embryonic stem cells

Embryonic stem cells are derived from 5-day-old human embryos. These cells can differentiate into any type of cell in the body (this ability is called “pluripotency”).

Scientists see great potential for stem cells in tissue replacement therapy, which is the ability to grow new tissue to replace the damaged in case of serious injuries. Another branch of clinical trials is the derivation of pigment epithelial (retina) cells from embryonic stem cells for the treatment of various eye diseases (retinal dystrophy, for example).

The danger of using other organisms’ stem cells (including embryonic), however, is that the recipient’s immune system may consider these cells as alien organisms and destroy them. Also, there is a possibility that the recipient could become infected with viruses and prions (infectious agents that can cause some neurodegenerative diseases).

Clinical studies using embryonic stem cells undergo a special ethical review. In many countries, these studies are limited by law.

2. Adult stem cells

Adult stem cells are undifferentiated cells found throughout the body, even in children. Since their main purpose is replacing dying cells and regenerating damaged tissue, they have less potential than embryonic stem cells. Today, however, adult stem cells are the most appropriate biomaterial for stem cell therapies.

These cells can primarily be found in the bone marrow, and to a much lesser extent, in the peripheral blood. For example, hematopoietic stem cells (blood-forming stem cells) form blood cells that provide oxygen transport, participate in the coagulation process, and protect against alien agents, bacteria, and viruses that determine the immune response. 

Mesenchymal (stromal) stem cells are capable of forming components of human tissues, including cells for bone, cartilage, organs, skeletal muscle, and the nervous system.

Differences between adult and embryonic stem cells:

  • Development potential: Embryonic stem cells have a much greater differentiation potential than adult stem cells. Adult stem cells can only develop into a limited number of cell types, while embryonic can develop into any cell type in the adult body. The latest studies, however, suggest that adult stem cells may have greater potential, such as the possible ability to differentiate into a wider range of specialized cell types.
  • Impact on the recipient’s immune system: Autologous (obtained from the patient’s body) adult human body stem cells have a clear advantage over embryonic: their transplantation (for example, stem cell transplant for lymphoma or stem cell transplant for multiple myeloma) does not cause transplant rejection by the recipient’s immune system.

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The transplantation of embryonic stem cells requires strong immunosuppressive medications to combat the rejection of new cells. And in any case, this puts the patient at risk of developing diseases that may be present in transplanted cells.

  • The question of “cell youth”: Adult stem cells are more likely to have abnormalities from DNA mutations that can occur for various reasons. The “youth” of embryonic stem cells means that they are less susceptible to mutations, and regenerate much faster than adult stem cells.

Conclusion: Despite ethical concerns, embryonic stem cells have an extremely high potential for the treatment of diseases. However, research should continue on adult stem cells.

3. Induced pluripotent stem cells (iPSCs)

With induced pluripotent stem cells, there is no risk of rejection by the immune system (which is very important for any stem cell transplantation); the ethical problems associated with the use of embryonic stem cells are also eliminated.

There is no invasive surgical procedure required to extract the necessary biomaterial; skin fibroblasts, hair follicles, and blood can serve as stem cell sources for further cultivation.

Today, iPSC clinical trials are being conducted to treat Parkinson’s disease, cataracts, and chronic lung diseases. Scientists are also studying their potential for growing nerve stem cells and human kidney cells.

4. Cord blood stem cells and amniotic fluid stem cells

Cord blood contains a large number of blood-forming stem cells which can be used to treat a wide range of diseases in gerontology and rehabilitation medicine. These cells have the greatest “repair” potential: They can differentiate into the cells of those organs or tissues that need to be “repaired”.

The main feature of cord blood stem cells is the possibility of providing biological “insurance” for health – and even life – for the next generation. After a child is born, the parents can keep the umbilical cord blood in a cryobank, providing the child with an added level of life insurance in case of serious illness or injury.

Amniotic cells have shown high therapeutic potential in the fight against immune diseases and inflammatory processes within the human body. For example, they can be used to treat diabetes, arthritis, cardiovascular, and neurodegenerative diseases.

Depending on the possibilities of differentiation (or simply tasks that these cells solve), they are conditionally divided into:

  • Hematopoietic stem cells (blood-forming) stem cells (HSCs) form a variety of blood cells that determine immunity, fight infections, carry oxygen, and are involved in blood coagulation.
  • Mesenchymal (stromal) stem cells (MSCs) can develop into bone, cartilage, and connective tissue cells, and can also form blood vessel elements. In addition to replenishing the lost elements of these tissues, MSCs can synthesize a large set of biologically active substances, which help them to change the behavior of other types of cells (immune system cells, for example).

Stem cell therapy and treatment

In the 1970s, stem cell rejuvenation became popular – these were so-called “injections of youth”, which only Hollywood actors and Soviet party nomenclature could afford.

Read more about the Regenexx procedure.

Today, hematopoietic stem cells and mesenchymal stem cells are used for therapeutic treatment. Hematopoietic stem cells are mostly used for transplantation in the treatment of malignant blood diseases.

Mesenchymal stem cells are widely used in regenerative medicine in cosmetology, gerontology, orthopedics, dentistry, periodontics, neurology, and other fields for:

  • Treatment of ischemic heart disease: stem cell therapy can limit the spread of the myocardial ischemia zone and restore the functional properties of the heart muscle.
  • Restoration of normal function of endocrine glands.
  • Treatment of severe neurological diseases (Alzheimer’s, Parkinson’s, degenerative diseases of the central nervous system, brain and spinal cord injuries, multiple sclerosis, etc.).
  • Additional strategies in the treatment of spinal cord injuries.
  • Reducing the pain during treatment for orthopedic diseases (for example, stem cell therapy for neck pain or stem cell therapy for herniated disc).
  • Treatment for severe eye diseases (glaucoma, macular degeneration, etc.) and traumatic eye injuries.
  • Regeneration of damaged areas of bone, cartilage, tendons, and ligaments.
  • Regeneration of periodontal tissues (treatment of damaged gum tissue, areas of implant placement or bone grafting, etc.).

How does stem cell therapy work?

  • Preparatory stage: Diagnosis and explanation of the procedure.
  • Obtaining stem cells from the patient or a donor. This is how stem cells are collected, depending on the type needed: Blood is taken from a vein, and bone marrow stem cells are collected through a special needle placed in the soft center (marrow) of the bone.
  • Stem cells are then grown in a biotechnology laboratory.
  • Different kinds of stem cell therapies can be carried out either as monotherapy or in combination with traditional surgical and/or medication treatment; therefore, at this stage, additional procedures could be prescribed to the patient.
  • After the cells have returned from the laboratory, they are transplanted into the patient’s body via a painless process called intravenous infusion. The blood delivers the new stem cells directly to the bone marrow, thanks to the so-called «homing effect». Transplanted stem cells begin to grow and reproduce healthy cells. The patient will remain under the doctor’s supervision for some time.

The patient may feel improvement within the first week after the procedure. After about 45 days, immunity and liver function is restored, and hematopoiesis (the process by which immature precursor cells develop into mature blood cells) improves.

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Read also:

How Much Does Stem Cell Therapy Cost: Detailed Review

Does Insurance Cover Stem Cell Therapy?

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