Stem Cells – Frequently Asked Questions
What are stem cells?
Stem cells are unspecialized cells found in the human body that have the ability to self-replicate and develop into a variety of different cell types. In fact, all of the cells and tissues found in the body originated from stem cells. There are multiple different types of stem cells that are involved with the developmental of the human body including hematopoietic, mesenchymal, neural and epithelial stem cells.
In addition to their role in developmental biology, stem cells have numerous therapeutic actions. Naturally, stem cells act as an internal repair system by supporting a multitude of tissue repair mechanisms, as well as replacing damaged and dysfunctional cells. Most of the therapeutic benefits of stem cells are believed to come from their ability to influence the behavior and activity of target tissues via the paracrine effect. The paracrine effect is the cell to cell communication between stem cells and other tissues. This communication involves cellular signals carried by specialized vehicles called exosomes which influence the behavior or activity of nearby and distant tissues in order to restore function. Stem cells also contain numerous growth factors which are thought to be the single most important characteristic of any given stem cell population.
Stem cells have been shown to exert a variety of therapeutic properties including anti-inflammatory, tissue repair, immune modulating and anti-microbial properties. These therapeutic properties often result in reduced inflammation, regeneration of healthy tissue, and improvement of cellular function. Considering these properties, stem cell therapy is being actively researched for treating numerous acute, chronic and degenerative diseases. It is also being research in regenerative and longevity medicine.
What are the main types of stem cells?
There are three main types of stem cells, adult stem cells (ASCs), which are derived from human tissue such as bone, fat, umbilical cord, etc., embryonic stem cells (ESCs) derived from human embryos, and induced pluripotent stem cells (iPSCs), adult stem cells that are genetically modified in the laboratory to be pluripotent.
Stem cells are often categorized by their potential to become different cell types. Totipotent stem cells are the earliest embryonic stem cell and can form every single cell type in the body including placental cells. Embryonic cells within the first couple of cell divisions after fertilization are the only cells that are considered totipotent. Totipotent stem cells give rise to Pluripotent stem cells which can develop into all other cell types in the body. Embryonic stem cells after the first couple cell divisions are considered to be pluripotent. Multipotent stem cells can develop into numerous cell types but are more limited in their potential than pluripotent cells. Multipotent stem cells remain in the body throughout life and replace old, damaged or dysfunctional cells. Adult stem cells and cord blood stem cells are considered to be multipotent.
Adult Stem Cells
Adult stem cells (ASCs) also known as somatic stem cells are unspecialized or undifferentiated cells in the body that can self-replicate and generate new cells. Their purpose in the body is to replace and regenerate damaged, diseased or injured cells. ASCs are found in various tissues including umbilical cord, placenta, bone marrow, muscle, fat and other tissues. There are a number of different types of ASCs including;
- Hematopoietic Stem Cells(HSCs) – Form red blood cells, white blood cells and other types of blood cells. Commonly used in the treatment of blood cancers.
- Mesenchymal Stem Cells (MSCs) – Form a variety of cell types including bone, cartilage, muscle and fat cells. Commonly used in regenerative medicine.
- Neural Stem Cells (NSCs) – Form cells of the nervous system including neurons and glial cells, etc.
- Epithelial Stem Cells (EpiSCs) – Form epithelial cells found in skin tissue, gastrointestinal tissue, etc.
Embryonic Stem Cells
Embryonic stem cells are derived from human embryos that have been fertilized in vitro and donated for research purposes. Embryonic cells within the first couple of cell divisions after fertilization are the only cells that are considered to be totipotent. Embryonic stem cells after the first couple cell divisions are considered to be pluripotent.
Induced Pluripotent Stem Cells
Induced pluripotent stem cells (iPSCs) are stem cells that are genetically modified by scientists in the laboratory. iPSCs are created by transferring embryonic genes into an adult stem cell causing it to revert back to an earlier developmental stage and become pluripotent.
Wharton’s jelly is a gelatinous tissue that surrounds the umbilical cord blood vessels and contains a high concentration of precursor mesenchymal stem cells. These precursor cells can be extracted, cultured and harvested in abundance and used for similar purposes as adult mesenchymal stem cells. Although this tissue is used in research its use in a clinical setting is less common than other stem cell tissues.
Although not a type of stem cell or a source of stem cells, Exosomes are becoming recognized as an integral component of cell to cell communication and a novel therapeutic tool for the treatment of various diseases. Exosomes are extraordinarily tiny particles found in all mammalian cells that act as a vehicle to transmit cellular messages between nearby and distance cells. Cellular communication plays important roles in many aspects of human health including development, immunity, cellular health and homeostasis, neurodegenerative disease, cardiovascular disease, orthopedic conditions and more. To find out more about exosomes please see our Exosomes page here.
What do stem cells do? How do they work?
Stem cells are unspecialized cells found in the human body that have the potential to self-replicate and develop into a variety of different cell types. By replacing damaged and dysfunctional cells, stem cells act as an internal repair system. However, most of the therapeutic benefits of stem cells are believed to come from their ability to influence the behavior and activity of nearby or target tissues via the paracrine effect. The paracrine effect is the cell to cell communication between stem cells and other tissues. This communication involves cellular signals to influence the behavior or activity of nearby or target tissues in order to restore function.
Stem cells also have anti-inflammatory, immune modulating and anti-microbial properties which are exhibited through the paracrine effect. They also contain numerous growth factors which are thought to be the single most important characteristic of any given stem cell population. These properties often result in regeneration of healthy tissue, reduced inflammation, and improvement of cellular function. Considering these properties, stem cell therapy is being actively researched for treating numerous acute, chronic and degenerative diseases.
How are stem cells administered?
Stem cells can be administered in a variety of different ways depending on the condition being treated. Common routes of administration include intravenous (into veins), intra-articular (into joints) and intrathecal (into spinal cord). For example, stem cells are injected locally into affected joints and soft tissue for most orthopedic conditions such as osteoarthritis or ligament/tendon injuries. A local anesthetic is used prior the procedure to reduce injection related pain. Other methods of stem cell administration including local injections into the eye, heart, brain and other organs are typically reserved for hospital or surgical suite settings as they are more invasive and have higher risk for complications.
Where do stem cells come from?
Stem cells were first discovered in mouse embryo and bone marrow. As research progressed researchers found stem cells in human embryos. However, due to the controversy of sourcing the human embryos, researchers had to look elsewhere. Over the course of many years researchers found stem cells in a variety of human tissues including bone marrow, fat tissue also known as adipose tissue, umbilical cord tissue, placental tissue, dental tissue and even urine. Patients receiving stem cell therapy either have their own cells collected and administered, which is called autologous stem cell therapy or have manufactured or donated stem cells administered, which is called allogeneic stem cell therapy. Both autologous and allogeneic stem cells have been shown to be safe.
How are stem cells harvested?
Patients may receive autologous stem cell therapy where stem cells are harvested from their own tissue or receive allogeneic stem cell therapy where stem cells are used from manufactured or donor tissue. Autologous stem cell therapy requires an invasive surgical procedure that is typically expensive and can be very painful. Bone marrow stem cells are collected by drilling into the posterior iliac crest, a region of pelvic bone near the low back, and removing a sample of bone marrow. This procedure can be very painful with pain lasting days or weeks, and often leaves a sizable scar. Adipose stem cells are collected by making one or two small incisions in the abdominal flanks then a liposuction device is used to remove samples of fat tissue. Due to the invasiveness and cost, autologous stem cell therapy is gradually being replaced by allogeneic stem cell therapy in the clinical setting. Allogeneic stem cell therapy does not require the patient to undergo invasive harvesting procedures prior to treatment. Many companies in the US offer allogeneic stem cells which are typically derived from umbilical or placental tissue. These products are required by US law to follow strict safety regulations and manufacturing processes. The stem cells are typically verified and characterized in the laboratory, screened for containments, bacteria, viruses, etc., and sterilized to stringent standards to ensure safety without diminishing their effectiveness.
Aren’t stem cells controversial?
Stem cell therapy became controversial when researchers were harvesting stem cells from human embryos. This type of stem cell, referred to as embryonic stem cell, is rarely used in treatment due to both controversial and ethical dilemmas surrounding the source of these cells. The less controversial and safer type of stem cell is called somatic stem cell or adult stem cell. These cells can be collected from a variety of adult human tissues including bone marrow, fat tissue also known as adipose tissue, umbilical cord tissue, placental tissue and others.
Is there research on stem cell therapy?
Yes. There is a significant amount of published research demonstrating the safety and efficacy of stem cell therapy in a number of conditions. Please see our Research Archive page for more detailed information regarding published research.
Is stem cell therapy safe?
The safety and tolerability of stem cell therapy has been clearly demonstrated in numerous published studies large numbers of patients treated for various different conditions. Commonly reported adverse events include headache, local injection site irritation and pain, fever, and others which are usually short lived and do not require additional treatment. Infection is a serious complication and is always a risk with any type of injection therapy. However, using universal administration safety protocols this risk is significantly minimized, if not eliminated. Serious short or long term adverse reactions to stem cell therapy such as blindness, cancer, blot clots, stroke, death, etc., have been reported, but are exceedingly rare. Factors that affect safety and tolerability include individual patient’s health, source of allogeneic stem cell products, stem cell dose, frequency of treatment and method of administration (IE. Injections into the eye, brain and spinal cord are higher risk for adverse effects compared to intravenous or local joint injections). For more information on the safety of stem cell therapy, please see our Safety Research Archive”.
Will the joint and soft tissue injections hurt?
For orthopedic conditions, stem cells can be injected into various joints and soft tissues such as tendons and ligaments for healing and repair of dysfunctional and or injured tissue. Such injections do not require local anesthesia, take only a matter of seconds and are relatively pain free. Many patients have compared the injection to that of a cortisone injection. The safety and efficacy of stem cell injections for orthopedic conditions has been reported in numerous studies. (For more detailed information please see our Safety Research Archive and Orthopedic Research Archive. Serious and severe adverse reactions to orthopedic stem cell injections are exceedingly rare. Common, self-limiting side effects are pain and swelling at injection site for 12-72 hours post treatment. These are alleviated by short term use of ice, pain relievers and other recommendations by the doctor. Infection is always a risk with any type of injection therapy, however using universal safety protocols this risk is significantly minimized if not eliminated.
How many stem cell treatments are typically necessary?
Each patient is unique with their own factors affecting their response to therapy and the need for additional treatment. For many a single treatment can provide significant, long lasting results, however others may need to repeat treatment over time usually every 3 to 12 months or as needed for optimal effects. The doctor assesses the patient’s response to treatment in a follow-up consultations to discuss additional treatments as needed.
How long will it take to see results?
Each patient is unique with their own factors affecting their response to therapy. There is no guarantee of what the results will be or the time it will take to see results. Some patients have reported immediate results while others have reported results within 3-6 months after treatment. Some patients who have received treatment only minimally improved or did not improve at all.
Is stem cell therapy covered by insurance?
Like many treatments in regenerative medicine, stem cell therapy is considered elective or experimental is not covered by insurance companies.
What are the FDA regulations, guidelines and concerns?
In 2017 the FDA released a comprehensive policy framework for regenerative medicine products including cellular therapies to more clearly describe what products are regulated as drugs, devices and/or biological products. Their risk-based approach for enforcement takes into account how products are being administered as well as the diseases and conditions for which they are intended to be used.
The FDA’s industry-friendly approach gives companies a three-year grace period starting in 2017 to describe their products or treatments in order to determine if they meet the criteria of “drugs” and thus require FDA approval.
The FDA’s frame work includes two final guidance documents. The first final guidance clarifies the FDA’s regulations of devices used to harvest, isolate and deliver cell based therapies. The second final guidance clarifies the criteria of “minimal manipulation” and “homologous use.”
“Treatments which use patient’s own cells that are minimally manipulated and applied to homologous use DO NOT require FDA approval”
Minimal manipulation means that the processing of human cells, tissues, and cellular and tissue-based products (HCT/P) does not alter the relevant biological characteristics of cells or tissues (21 CFR 1271.3(f)(2)).
Homologous use means the repair, reconstruction, replacement, or supplementation of a recipient’s cells or tissues with an HCT/P that performs the same basic function or functions in the recipient as in the donor (21 CFR 1271.3(c)), including when such cells or tissues are for autologous use. HCT/P is considered to be for homologous use when it is used to repair, reconstruct, replace, or supplement:
- Recipient cells or tissues that are identical (e.g., skin for skin) to the donor cells or tissues, and perform one or more of the same basic functions in the recipient as the cells or tissues performed in the donor; or,
- Recipient cells or tissues that may not be identical to the donor’s cells or tissues, but that perform one or more of the same basic functions in the recipient as the cells or tissues performed in the donor.
The frame work also includes two draft guidance documents. The first draft guidance addressed how the FDA intends to simplify and streamline application of regulations on devices. The second draft guidance describes programs for approval such as the Regenerative Medicine Advanced Therapy (RMAT) designation.
FDA Concerns: Consumer Update
- Unproven stem cell therapies can be particularly unsafe.
- Clinics may inappropriately advertise stem cell clinical trials without submitting an IND and or falsely advertise that FDA review/approval is unnecessary.
- Potential safety concerns for unproven treatments include contamination, administration site reactions, transformation of cells into inappropriate cell types, failure of cells to work as expected, and growth of tumors.
- The only stem cell-based products that are FDA approved are blood forming stem cells (hematopoietic progenitor cells) derived from cord blood.
Brought to you by:
Ahvie Herskowitz, MD, President of ACAM
Director of Anatara Medicine
Founder of San Francisco Stem Cell Treatment Center
Clinical Professor of Medicine at UC San Francisco (2014)
(Read Dr. Herskowitz’s Bio Here)
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