Stem cell therapy follows a three-stage process: harvesting cells from a source, processing them in a lab, and delivering them to the target area in your body. The entire procedure, from extraction to injection or infusion, often takes place within a single day for outpatient treatments, though some approaches require weeks of lab preparation between harvesting and delivery.
What that process looks like varies significantly depending on the type of stem cells used, the condition being treated, and where the cells come from. Here’s what happens at each stage.
Where the Stem Cells Come From
The first step is sourcing the cells. Stem cells used in therapy come from a few key places: your own body (autologous), a donor (allogeneic), or stored cord blood. The source determines how the harvesting step works.
Bone Marrow
Bone marrow remains one of the most common sources. A physician uses a specialized needle, typically about 10 cm long, to aspirate marrow from the back of the pelvis. The primary extraction site is the posterior superior iliac spine, a bony ridge located about 5 to 8 cm above and to the side of the top of the gluteal cleft. If the yield drops from that spot, the practitioner moves to secondary sites on the pelvis. The procedure is done under local or general anesthesia, and the needle is repositioned through multiple passes to collect enough material.
Fat Tissue
Adipose (fat) tissue is another popular source, especially in orthopedic and cosmetic applications. A small liposuction procedure removes fat from the abdomen or thigh, and the stem cells are then separated from the fat tissue during processing. This approach appeals to many patients because fat is abundant and relatively easy to collect.
Cord Blood and Donor Cells
For certain blood cancers and genetic disorders, stem cells come from umbilical cord blood collected at birth or from a matched donor’s bone marrow or blood. Multiple cord blood products are FDA-approved for transplantation in patients with blood-forming disorders. When donor cells are used, the patient doesn’t go through a harvesting procedure at all. Instead, the preparation focuses on conditioning the patient’s body to accept the new cells.
How the Cells Are Processed
Raw tissue pulled from bone marrow or fat isn’t ready for direct use. It contains blood, fat, bone fragments, and other material mixed in with the stem cells. The lab processing step isolates and concentrates those cells so the final product contains a therapeutically useful dose.
The most common technique is centrifugation, which spins the harvested material at varying speeds to separate components by weight. Heavier red blood cells settle to the bottom, lighter plasma rises to the top, and stem cells collect in a middle layer. In some protocols, this spinning happens in stages at different speeds to further purify specific cell types. For point-of-care treatments (done same-day in a clinic), the entire processing step might take 15 to 30 minutes using a bedside centrifuge. More complex therapies require days or weeks in a specialized lab, where cells are grown and multiplied in culture before being returned to the patient.
The processing stage is also where a key regulatory line exists. The FDA distinguishes between “minimally manipulated” cells (essentially concentrated but not altered) and cells that have been significantly changed through culturing or genetic modification. Most same-day clinic procedures aim to stay within the minimal manipulation category.
How Stem Cells Are Delivered
Once processed, the cells reach your body through one of two main routes: local injection or intravenous infusion. The choice depends entirely on what’s being treated.
Local Injection
For joint, tendon, and tissue injuries, stem cells are injected directly into or around the problem area. Intra-articular injections place cells inside a joint like the knee or shoulder, while extra-articular injections target surrounding tendons or fascia. Imaging guidance (ultrasound or fluoroscopy) is often used to ensure precise placement.
The advantage of local injection is concentration. Cells largely stay where they’re placed, producing their effects right at the site of damage. They release signaling molecules that reduce inflammation and support tissue repair in that specific area. For joint injections, the effective range appears to be 50 to 100 million cells per dose.
Intravenous Infusion
For systemic conditions like autoimmune diseases or certain inflammatory disorders, stem cells are infused through a vein, similar to receiving an IV drip. The cells enter the bloodstream and circulate through the body. They don’t distribute evenly, though. Most cells initially accumulate in the lungs, where they get temporarily trapped in tiny blood vessels before gradually redistributing to the liver, spleen, and kidneys.
IV delivery works best when the therapeutic goal is bodywide immune modulation rather than repairing one specific spot. The cells influence the immune system broadly, which is why this route is used in clinical trials for conditions like Crohn’s disease and graft-versus-host disease.
What Recovery Looks Like
For outpatient procedures like joint injections or same-day bone marrow concentrates, you can typically go home the same day. The harvest site (pelvis or fat collection area) may be sore for several days. The injection site itself can feel swollen or tender.
In the first few days after treatment, some patients notice reduced inflammation, initial improvements in mobility, and decreased pain. During weeks one through four, the cells begin more active repair work, and patients often report improved energy, better flexibility, and enhanced sleep quality. Full benefits, for those who respond, can take several months to emerge. Some patients notice changes within days, while others see gradual improvement over a longer window.
Activity restrictions in the early phase are straightforward: prioritize rest and sleep, avoid strenuous activity, and gradually reintroduce gentle exercise. For bone marrow transplants used to treat cancers, recovery is far more intensive and involves weeks of hospitalization and immune suppression, which is a fundamentally different experience from outpatient regenerative procedures.
What’s Actually FDA-Approved
This is where many people get confused. The FDA has approved a specific set of cellular and gene therapy products, and most are for serious conditions like blood cancers, genetic disorders, and severe burns. These include cord blood products for transplantation, engineered immune cell therapies (CAR-T cells) for certain leukemias and lymphomas, cultured skin grafts for wounds, and a cultured cartilage product for knee repair. A mesenchymal stem cell product was also approved for graft-versus-host disease in children.
The vast majority of stem cell clinics offering treatments for joint pain, back pain, neuropathy, or anti-aging are operating outside the scope of FDA-approved therapies. That doesn’t automatically mean the treatments are ineffective, but it does mean they haven’t gone through the full regulatory approval process, and outcomes are less predictable.
What It Costs
Stem cell therapy averages around $10,000 per treatment. Knee injections tend to fall on the lower end, typically $5,000 to $10,000. Back and shoulder treatments range from $5,000 to $15,000. Neuropathy treatments start around $2,500 but have been climbing into the tens of thousands. Vision-related stem cell procedures start around $20,000 and go higher, and cord blood treatments for neurological conditions outside the U.S. generally run $20,000 and up.
Insurance generally does not cover these procedures. Medicare will pay for established bone marrow transplants used in cancer treatment, but it does not cover unproven stem cell therapies offered at private clinics. For most patients pursuing regenerative stem cell treatments for joints or chronic pain, the cost is entirely out of pocket.