Every minute, your body replaces millions of cells—and behind that constant renewal are stem cells, the raw material that makes it all possible. They’re not just a scientific curiosity; they’re the foundation of some of the most promising medicine being practiced today.

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Self-renewal ability: Produce identical copies · Differentiation potential: Develop into specialized cells · Common sources: Bone marrow, umbilical cord blood · Key locations: Bone marrow, amniotic fluid · Primary uses: Treat blood disorders, regenerate tissues

Quick snapshot

1Confirmed facts
  • Stem cells self-renew and differentiate into specialized cell types (Mayo Clinic)
  • Embryonic stem cells come from 3-to-5-day-old blastocysts with about 150 cells (Mayo Clinic)
  • Bone marrow transplants use stem cells from patient, donor, or cord blood (Mayo Clinic PDF)
2What’s unclear
  • Exact costs of treatments vary widely by provider and region
  • Long-term outcomes for some experimental therapies remain under study
  • Precise incidence rates for graft-versus-host disease not publicly standardized
3Timeline signal
  • Mayo Clinic published iPS cell safety method: September 25, 2012 (Mayo Clinic News)
  • Patient survey on therapy motivations ran November 2018 through February 2020 (Mayo Clinic News)
4What’s next
  • Mayo Clinic investigating adult stem cells for hip replacements and heart failure (Mayo Clinic News)
  • Trials underway for mesenchymal stem cells targeting chronic kidney disease (Mayo Clinic Research)

Key facts about stem cells are summarized in the table below.

Label Value
Definition Cells that self-renew and specialize
Primary Location Bone marrow
Top Use Blood disorder treatments
Embryo Stage 3 to 5 days old (blastocyst)
Blastocyst Cell Count About 150 cells
Patient Survey Sample 533 patients

What are stem cells in simple terms?

Stem cells are the body’s raw material—cells that have not yet decided what to become. Unlike a muscle cell or a nerve cell, which are locked into their roles, a stem cell can make copies of itself and transform into other cell types when the body needs them. According to Mayo Clinic, this two-part capacity—self-renewal and differentiation—is what makes stem cells uniquely powerful.

Key properties of stem cells

Two properties define every stem cell: the ability to divide and produce more stem cells, and the ability to become specialized cells such as blood, muscle, or nerve cells. Hematopoietic stem cells residing in bone marrow produce all blood cells, making them essential for immune function and oxygen transport.

  • Self-renewal: Stem cells can copy themselves indefinitely, maintaining a reservoir for future use
  • Differentiation: Under the right signals, they develop into specific cell types
  • Repair function: They migrate to injured tissue and help rebuild what was damaged

How stem cells differ from other cells

Most cells in the body are differentiated—they do a specific job and cannot change. A skin cell cannot become a liver cell. A stem cell, however, carries no fixed identity, which is exactly the point: it waits in reserve until the body needs it. This flexibility makes stem cells the building blocks for organs, tissues, blood, and the immune system.

What to watch

Mayo Clinic researchers analyzed 533 musculoskeletal patients (median age 68) from November 2018 through February 2020 and found that patients increasingly seek stem cell therapies as alternatives to conventional surgery—but that demand does not always match proven clinical outcomes.

Confirmed

  • Stem cells from bone marrow are used in transplants for blood cancers and disorders
  • Embryonic stem cells raise ethical concerns because they are derived from human embryos
  • Adult stem cells may carry irregularities from environmental toxins or replication errors

Uncertain or evolving

  • Long-term efficacy data for some experimental adult stem cell applications
  • Precise cost benchmarks across different clinics and regions
  • How iPS cell therapies will perform in large-scale human trials

What are the types of stem cells?

Scientists categorize stem cells by their potential to differentiate. The broader that potential, the more versatile—and the more scrutinized—the cell type tends to be.

Embryonic stem cells

Embryonic stem cells are pluripotent, meaning they can become virtually any cell in the body. They are harvested from 3-to-5-day-old embryos called blastocysts, which contain roughly 150 cells at that stage. Mayo Clinic notes that this versatility makes them extraordinarily valuable for research, but also raises ethical concerns tied to their derivation from human embryos. They also carry risks of immune rejection or failure to function properly after transplantation.

Adult stem cells

Adult stem cells are found in tissues such as bone marrow, fat, and muscle. While their differentiation potential is more limited than embryonic cells, they are more versatile than scientists originally believed—research from Mayo Clinic News shows adult stem cells are being investigated for treating diabetes, heart disease, and liver conditions. Hematopoietic stem cells in bone marrow produce all blood cells and are the source of most transplant procedures today.

Induced pluripotent stem cells

Induced pluripotent stem cells (iPS cells) are bioengineered from adult tissue cells that have been reprogrammed to behave like embryonic stem cells. Mayo Clinic News reports that a key challenge is that residual pluripotent cells in iPS preparations can form tumors. In 2012, Mayo Clinic developed a method using chemotherapeutic agents to eliminate these tumor-forming cells, a breakthrough that made therapeutic use safer. The implication is that iPS therapy is moving closer to clinical reality, but only after the safety problem is solved.

The trade-off

Embryonic stem cells offer maximum versatility; adult stem cells offer safety and fewer ethical concerns. iPS cells attempt to combine both benefits, but current manufacturing standards (cGMP) are essential to ensure they perform consistently in treatments.

Where do you get stem cells from?

The source of stem cells matters both for the procedure itself and for what the cells can ultimately become. Three routes account for the vast majority of clinical use.

Bone marrow collection

Bone marrow is the richest and most established source of hematopoietic stem cells. A needle draws liquid marrow—typically from the hip bone—under anesthesia. These cells are used in bone marrow transplants for leukemia, lymphoma, and other blood disorders. Mayo Clinic confirms that stem cells for transplant can come from the patient themselves, a matched donor, or stored cord blood.

Umbilical cord blood

Blood remaining in the umbilical cord after birth contains stem cells that have been used in clinical trials for cancer and blood diseases. Mayo Clinic Research notes that cord blood units are banked and used in transplants for unrelated patients under safety monitoring protocols. The advantage is that cord blood stem cells are more adaptable immunologically, reducing the risk of rejection.

Peripheral blood

Stem cells also circulate in peripheral blood, though in lower concentrations. When needed, patients receive a daily injection of a growth factor for several days before collection. Mayo Clinic Video explains that the process—called apheresis—filters blood through a machine that isolates the stem cells and returns the rest to the donor. This method is less invasive than bone marrow collection but requires pre-treatment with medication.

Amniotic fluid

Stem cells also exist in amniotic fluid, which surrounds a developing baby. These cells show promise for regenerative applications, though research is earlier-stage than bone marrow or cord blood sources.

Bottom line: Bone marrow and cord blood are the most clinically proven sources for transplant and therapy. For patients weighing treatment options, the source determines not only availability but the risk profile—older adult stem cells may carry accumulated irregularities, while cord blood offers greater immunological flexibility.

What do stem cells do?

Stem cells serve two broad purposes in medicine: repairing damaged tissue and replacing cells that disease has destroyed. Their versatility makes them relevant across a widening range of conditions.

Role in body repair

When tissue is injured, stem cells migrate to the site and begin dividing. Some become the specific cells needed for repair—new muscle fibers, blood vessels, or cartilage. Mayo Clinic notes that stem cell therapies promote repair of diseased tissue as an alternative to organ transplants, which are limited by donor supply and surgical risk. Mayo Clinic is actively investigating adult stem cells for hip replacement recovery and heart failure treatment.

Applications in transplants

Bone marrow transplants are the oldest and most established stem cell application. In this procedure, high-dose chemotherapy or radiation destroys a patient’s diseased bone marrow, which is then replaced with healthy stem cells that rebuild the blood and immune systems. Mayo Clinic News studied 533 musculoskeletal patients and found that pain relief and avoidance of surgery were primary motivations for seeking stem cell therapy.

Timothy Nelson, M.D., Ph.D., Lead author, Mayo Clinic researcher:

“Pluripotent stem cells show great promise in the field of regenerative medicine; however, the risk of uncontrolled cell growth will continue to prevent their use as a therapeutic treatment.”

Beyond transplants, stem cell research targets brain tumors, breast cancer side effects, and xerostomia (dry mouth following radiation therapy), according to Mayo Clinic Research Lab. The common thread across these applications is the challenge of immune rejection and tumorigenesis, as documented in PMC/NIH research.

The catch

Stem cells used in regenerative medicine for conditions like diabetes, heart failure, and degenerative diseases show genuine promise—but the gap between laboratory results and proven clinical outcomes remains significant for many applications.

What are the risks of using stem cells?

Every medical intervention carries risk, and stem cell therapies are no exception. The specific dangers depend on the cell type, the source, and whether the cells come from the patient or a donor.

Transplant complications

Graft-versus-host disease (GVHD) occurs when donated stem cells attack the recipient’s tissues. Mayo Clinic specifies that GVHD risks are higher with unrelated donors and can manifest as rash, diarrhea, liver dysfunction, and organ damage. Beyond GVHD, transplant risks include stem cell failure (the graft does not take), organ damage from high-dose conditioning chemotherapy, and serious infections during the immune-suppressed recovery period.

Therapy side effects

iPS cell therapy carries a specific risk identified by Mayo Clinic News: residual pluripotent cells can form tumors after transplantation. Mayo Clinic’s 2012 safety method addresses this by using chemotherapy agents to weed out problem cells before therapy. Embryonic stem cells can also trigger immune rejection or simply fail to integrate and function after transplant, per Mayo Clinic.

Alyson Smith, Ph.D., Co-author, Mayo Clinic researcher:

“This research outlines a strategy to make stem cell therapies safer for our patients while preserving their therapeutic efficacy, thereby removing a barrier to translation of these treatments to the clinic.”

What to watch

Unproven stem cell clinics marketed directly to patients—sometimes outside clinical trials—have raised concerns from regulators. Patients should verify that any stem cell treatment they consider is part of a registered trial or approved protocol, not a commercial offering without peer-reviewed evidence.

The challenges in stem cell therapy documented by PMC/NIH include both immune rejection and tumorigenesis, confirming that safety remains the central research priority before wider therapeutic deployment.

Related reading: stem cells types and sources · stem cell basics

Additional sources

youtube.com, mayoclinic.org

Fundamentally, stem cells are animal cells able to differentiate present in sources like bone marrow, powering therapies for blood disorders.

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Frequently asked questions

How to increase your stem cells?

A healthy lifestyle supports natural stem cell function. Regular exercise, adequate sleep, and a balanced diet rich in antioxidants appear to benefit the body’s own stem cell activity. Some research suggests intermittent fasting may mobilize stem cells from bone marrow, though clinical evidence is still developing.

What food is rich in stem cells?

No food directly contains stem cells. However, foods rich in omega-3 fatty acids (fatty fish, walnuts), antioxidants (blueberries, dark leafy greens), and zinc (pumpkin seeds, legumes) support the environment in which stem cells operate most effectively.

What diseases can stem cells treat?

Bone marrow transplants treat blood cancers (leukemia, lymphoma), aplastic anemia, immune deficiencies, and certain genetic disorders. Research targets include diabetes, heart failure, chronic kidney disease, and degenerative joint conditions.

What is the average cost of a stem cell treatment?

Costs vary widely depending on the condition, cell source, clinic, and country. Bone marrow transplants involving hospital stays and conditioning chemotherapy typically run tens of thousands to over $100,000 in the United States. Experimental therapies offered outside clinical trials may quote widely different prices with limited insurance coverage.

What are stem cells in plants?

Plants have meristem cells that function analogously to stem cells in animals—they divide and differentiate to produce new roots, stems, leaves, and flowers throughout the plant’s life. Unlike animal stem cells, plant meristems remain active throughout the organism’s lifespan in localized regions called apical meristems.

Where are stem cells found in plants?

Plant stem cells (meristem cells) are located at the tips of roots and shoots, in axillary buds, and in vascular cambium. These regions continuously produce new tissue, allowing plants to grow taller and wider throughout their lives.

What is the most common way to get stem cells?

Bone marrow aspiration remains the most established method for collecting hematopoietic stem cells for transplant. For donors, peripheral blood stem cell collection via apheresis after growth factor stimulation is increasingly common and less invasive than surgical marrow harvest.

For patients weighing treatment options, the choice is increasingly clear: stem cell therapy holds real promise for blood disorders, certain cancers, and emerging applications in regenerative medicine—but it demands the same evidence standards as any other medical intervention. Seek treatment through registered clinical trials or established transplant centers, not commercial clinics operating outside peer-reviewed oversight.