What Is Stem Cell Therapy and How Does It Work? A Physician's Plain-English Guide
What is stem cell therapy and how does it work? Dr. Daren Brooks, D.O. explains the science, what's FDA-approved vs. investigational, and how to evaluate it saf
What Is Stem Cell Therapy, Exactly?
If you've spent any time researching options for chronic pain, joint damage, or a slow-healing injury, you've probably come across stem cell therapy — often marketed as a way to "regenerate" damaged tissue without surgery.
But the term gets used loosely, and the marketing rarely matches the science.
At The Bridge Health Recovery Center, our guests ask us about it often, so let's start with a plain-English definition.
Stem cells are the body's raw materials — cells with the potential to develop into many different specialized cell types (muscle, cartilage, bone, nerve, and more) and to divide and renew themselves.
How Stem Cell Therapy Works in the Body
In a typical procedure, stem cells are harvested from the patient (autologous) or from a donor source such as umbilical cord tissue (allogeneic), concentrated in a lab or point-of-care device, and then injected or infused into the target area — a joint, the spine, or intravenously for systemic effect.
Once introduced, the theory is that stem cells: Travel to areas of injury or inflammation, guided by chemical signals released by damaged tissue Release growth factors and signaling molecules that may reduce local inflammation Support the recruitment and activity of the body's own repair cells In some laboratory and animal models, differentiate into replacement tissue cells Human clinical evidence for that last mechanism — actual differentiation into new, functional tissue after injection — remains limited for most orthopedic and pain applications.
Most of the observed clinical benefit researchers currently attribute to the anti-inflammatory and modulating effects, not tissue regrowth.
This is a rapidly evolving research area, and legitimate scientists are honest that the full mechanism, and its real-world magnitude of benefit, is still being studied.
Types of Stem Cells Used in Treatment
Not all "stem cell therapy" is the same.
The source and preparation method matter a great deal: Bone marrow-derived (BM-MSCs): Harvested from the patient's own hip bone, concentrated, and re-injected.
One of the more studied autologous sources for orthopedic use.
Adipose-derived (fat-derived): Collected via a mini-liposuction procedure, processed to isolate stem cells, then injected.
What's FDA-Approved vs. Investigational
This is the single most important section of this article, because it's where most marketing misleads patients.
The FDA has approved certain stem cell-based products — but almost exclusively hematopoietic (blood-forming) stem cells derived from bone marrow, peripheral blood, or umbilical cord blood, used to treat specific blood and immune system disorders like certain leukemias and lymphomas.
That is a narrow, well-defined category.
For the uses most commonly marketed to chronic pain, orthopedic, and cosmetic patients — knee osteoarthritis, back pain, joint injuries, anti-aging, general "regeneration" — these treatments are, with rare exceptions inside approved clinical trials, investigational and not FDA-approved .
Conditions People Explore Stem Cell Therapy For
Patients and clinics discuss stem cell and related regenerative approaches for a wide range of conditions, including: Knee, hip, and shoulder osteoarthritis Degenerative disc disease and chronic back pain Tendon and ligament injuries (rotator cuff, Achilles, ACL) Post-surgical recovery and slow-healing wounds Chronic pain conditions with an inflammatory component Emerging research, particularly in orthopedic applications like knee osteoarthritis, suggests some patients report reduced pain and improved function following certain stem cell or PRP protocols — but study quality varies widely, placebo response in injection studies is notoriously high, and long-term data is still limited.
Reputable researchers describe the evidence as "promising but not yet definitive," which is a very different message than "proven cure" — a phrase you should never trust from any provider.
An inside look at how The Bridge approaches chronic pain and nervous system recovery.
What to Expect During Treatment
If you and a physician decide to explore a legitimate, well-supervised regenerative procedure, the general process typically looks like this: Comprehensive evaluation: Full medical history, imaging, and a discussion of your goals and realistic expected outcomes.
Cell collection: A minor procedure to draw bone marrow or fat tissue (for autologous treatments), or preparation of a donor-derived product.
Processing: Concentration of the cell sample, ideally with documented quality testing.
Injection or infusion: Delivered to the target joint, tissue, or intravenously, sometimes with imaging guidance for accuracy.
Risks, Limitations, and Realistic Expectations
Every medical procedure carries risk, and stem cell therapy is no exception.
Documented risks include infection at the injection or harvest site, pain or swelling, and — in rare but serious cases reported to the FDA — tumor formation and other serious complications, particularly with poorly regulated or improperly sourced products.
Beyond physical risk, there's a financial and emotional risk: patients spending significant out-of-pocket money on a treatment with uncertain benefit, sometimes delaying evidence-based care in the process.
Setting realistic expectations matters: 💡 Clinical Insight "May support recovery" and "some patients report improvement" are honest descriptions of current evidence.
How to Spot an Unproven or Predatory Clinic
Because this space is loosely regulated, learning to spot warning signs protects both your health and your finances.
Be cautious of any clinic that: Promises cures, guarantees, or specific success percentages Treats nearly every condition with the same product or injection Won't clearly answer whether their product is FDA-approved for your condition Pressures same-day payment or discourages you from seeking a second opinion Has no licensed physician actually reviewing your case, or relies heavily on non-medical sales staff Lacks any published research, registered clinical trial, or transparent outcomes tracking The FDA maintains public communications naming specific clinics under enforcement action — it's worth a search before committing to any provider.
When in doubt, get a second, independent medical opinion from a physician with no financial stake in the treatment.
"I tell patients the same thing I'd want a doctor to tell someone I love: ask who's regulating this, what happens if it doesn't work, and what your alternatives are — before you spend a dollar." — Dr.