Stem Cell Therapy for Arthritis: Types, Protocols, and What the Evidence Actually Shows

Stem cell therapy for knee arthritis has more outcomes data than any other joint, and that data shows modest gains: a 2017 meta-analysis in PLOS ONE (Yubo et al.) of 11 randomized trials and 582 patients found better pain and function scores than controls at 12 to 24 months. The trials are small, results differ by cell source and disease stage, no stem cell product is FDA approved for arthritis, and the 2019 American College of Rheumatology guideline recommends against these injections for knee and hip osteoarthritis.

Stem cell therapy for arthritis, also called mesenchymal stem cell (MSC) injection, orthobiologic injection or regenerative injection therapy, has moved from fringe science to an active field of clinical research in the past decade. It is still not a standard of care, and quality varies enormously depending on where you go and what cells are used. For patients with moderate knee osteoarthritis or refractory rheumatoid arthritis who have exhausted conservative options, the evidence is enough to justify a serious conversation with a qualified orthopedic, sports medicine or rheumatology physician.

Four factors decide whether the treatment is worth considering: which joint is affected, how advanced the arthritis is, which cell source is used, and whether the cost makes sense next to cheaper options such as physical therapy, weight loss and corticosteroid injections. The stem cell therapy treatment guide explains the therapy itself across all conditions.

How Does Stem Cell Therapy Work for Arthritis?

Mesenchymal stem cells, also called mesenchymal stromal cells, are adult cells that can become cartilage, bone or fat cells in the laboratory. In an arthritic joint they appear to work mainly by signaling rather than by turning into new cartilage. They release growth factors and anti-inflammatory cytokines and shift local immune cells toward repair, which is why the researcher Arnold Caplan proposed calling them medicinal signaling cells.

That mechanism explains the pattern in the trials. Pain and function scores tend to improve more reliably than cartilage thickness on MRI. In osteoarthritis, the target is a joint where cartilage is wearing down and the lining is inflamed. In rheumatoid arthritis, an autoimmune disease, the target is the immune response itself, so cells are often given by intravenous infusion rather than into a single joint.

The Three Main Cell Sources

Not all stem cell injections are the same. The cell source matters enormously for both efficacy and cost. Here is what you need to know about each option.

Bone Marrow Concentrate (BMC)

BMC is drawn from the patient’s own iliac crest using a needle aspiration procedure done under local anesthesia. The aspirate is then spun in a centrifuge to concentrate mesenchymal stem cells (MSCs), platelets, and growth factors. The whole process takes about 90 minutes in a clinic setting.

BMC is an autologous, same-day procedure, so it is regulated as minimally manipulated tissue rather than as a drug, and no culture expansion is required. This keeps costs lower, typically $3,000 to $6,000. The tradeoff is that MSC concentration in bone marrow declines with age, so a 65-year-old may receive far fewer stem cells than a 40-year-old from the same volume of aspirate.

A randomized trial at Mayo Clinic in Florida, published in The American Journal of Sports Medicine (Shapiro et al., 2017), injected BMC into one arthritic knee and saline into the other in 25 patients with osteoarthritis in both knees. Pain fell substantially in both knees at one week, three months and six months, and the difference between BMC and saline was not statistically significant. No serious adverse events occurred, which supports the procedure's short-term safety more than its benefit.

Adipose-Derived Stromal Cells (ADSCs)

Fat tissue yields many times more MSCs per gram than bone marrow. Adipose-derived cells are harvested via a mini-liposuction procedure under local anesthesia, then processed in a centrifuge or enzymatic digestion to produce a stromal vascular fraction (SVF).

SVF contains not just MSCs but also endothelial progenitor cells, pericytes, and immune-modulating macrophages, which may contribute to its anti-inflammatory effects. The same-day SVF procedure costs $5,000 to $9,000. Culture-expanded ADSC products, which grow the cells in a lab to much higher numbers, require an FDA Investigational New Drug (IND) application and are available only in clinical trials or outside the US.

A 2019 randomized trial in Regenerative Medicine (Freitag et al., n=30) from Australia compared culture-expanded adipose-derived MSCs, given as one or two injections of 100 million cells, with continued conservative management in knee OA. At 12 months, both injection groups had clinically significant pain and function gains, and MRI scoring suggested slower disease progression. The study was small, several authors worked for a commercial stem cell provider, and its lab-expanded cells are not the same product as same-day SVF in US clinics.

Umbilical Cord-Derived MSCs (UC-MSCs)

Cord-derived MSCs come from Wharton’s jelly, the gelatinous tissue inside umbilical cords donated after healthy births. These cells are allogeneic, meaning they come from a donor, not the patient. They are also younger, more proliferative, and more immunosuppressive than adult-derived MSCs.

Because they are processed and stored in advance, UC-MSC products can be administered as an off-the-shelf injection. The FDA classifies these as more than minimally manipulated biologics, so legitimate US clinical use is generally restricted to IND-approved trials. Products sold outside that framework are operating in a legal gray zone.

A 2019 randomized phase I/II trial in Stem Cells Translational Medicine (Matas et al., n=26) from Chile compared UC-MSC injections with hyaluronic acid in knee OA. Patients who received two UC-MSC doses six months apart had significantly lower WOMAC pain scores than the hyaluronic acid group at 12 months, which suggests dosing matters. No severe adverse events were reported, though a trial this size cannot detect rare harms.

Clinical Evidence: Osteoarthritis vs. Rheumatoid Arthritis

Knee Osteoarthritis

Knee OA is the best-studied indication. A 2017 meta-analysis in PLOS ONE (Yubo et al.) pooled 11 RCTs involving 582 patients and found that MSC treatment produced significantly better VAS pain and IKDC function scores than controls at 24 months, and better WOMAC and Lequesne scores at 12 months. Most included trials were small, and cell products, doses and control treatments varied widely.

Importantly, disease stage matters. Kellgren-Lawrence grade 2 to 3 patients respond significantly better than grade 4. Once bone-on-bone disease is established, stem cells are not likely to regenerate enough cartilage to make a meaningful difference, and total knee replacement may be the more honest recommendation.

For hip OA, the evidence is thinner. Published hip studies are few, most enroll small numbers of patients without a control group, and the data are too sparse to draw firm conclusions.

What the outcomes data shows for knee arthritis

The controlled trials most often cited for stem cell therapy in knee arthritis point in a favorable direction on pain and function, with one notable null result against saline. The table summarizes what each one tested and found.

The triple-blind Iranian trial by Emadedin et al. (2018) enrolled Kellgren-Lawrence grade 2 to 4 patients and reported no major adverse events. Across these studies, follow-up rarely passes two years, and none is large enough to settle whether cartilage is actually preserved. For more on the knee specifically, see stem cell therapy for knees and the knee osteoarthritis overview.

Rheumatoid Arthritis

RA is an autoimmune disease, and MSCs have immunosuppressive properties that make them theoretically well-suited for this condition. They suppress T-cell proliferation, reduce pro-inflammatory cytokines like TNF-alpha and IL-6, and promote regulatory T-cell activity.

A 2013 study in Stem Cells and Development (Wang et al.) enrolled 172 patients with active RA who had responded inadequately to standard medication, including disease-modifying antirheumatic drugs (DMARDs). Patients who received intravenous UC-MSC infusions alongside DMARDs improved significantly on American College of Rheumatology criteria, the DAS28 score and the Health Assessment Questionnaire, with benefits lasting three to six months. Serum TNF-alpha and IL-6 fell and regulatory T cells rose; the DMARD-only group showed no such gains.

The evidence for RA is promising but thinner than for knee OA, and most trials used intravenous infusions rather than intra-articular injections, which is a different delivery model entirely. Rheumatologists still treat RA with DMARDs and biologic drugs first; the rheumatoid arthritis treatment guide covers those options.

Stem Cell Therapy for Hip Arthritis: Benefits, Safety and What to Expect

Stem cell therapy for hip arthritis uses the same cell sources as knee treatment, but the evidence is much thinner. Published hip studies are mostly small case series, so reported benefits such as lower pain and better walking tolerance cannot yet be separated from placebo effects and natural fluctuation. The 2019 ACR and Arthritis Foundation guideline includes the hip in its strong recommendation against stem cell injections.

What to expect from a hip injection

The hip joint sits deep beneath muscle, so the injection is placed into the joint capsule under ultrasound or fluoroscopy (live X-ray) guidance. For autologous products, bone marrow or fat is harvested the same day. Recovery follows the knee protocol: a few days of soreness, protected walking, then progressive physical therapy.

Who is unlikely to benefit

Patients with advanced hip osteoarthritis, where the joint space has collapsed, respond poorly to any injection. Total hip replacement has decades of outcome data and is the established option at that stage. Mild to moderate hip OA with persistent pain after physical therapy and weight management is the group in which a trial of biologic injection is most often discussed.

Injection Protocols

For joint injections, ultrasound guidance is standard of care. Blind injections are less accurate and should not be accepted at this price point. The injection is typically placed in the suprapatellar pouch for knee procedures, with real-time imaging confirmation.

Most protocols use a single injection. Some clinics do a series of two to three injections spaced four to six weeks apart, particularly when combining stem cells with PRP (platelet-rich plasma). The evidence base for multi-injection protocols versus single-injection is not yet robust, and some physicians believe a single well-executed injection is preferable to diluting cells across multiple doses.

After injection, a standard protocol includes 48 to 72 hours of reduced activity, avoidance of anti-inflammatory medications such as ibuprofen and naproxen for two to four weeks (as these can blunt the biological response), and a structured physical therapy program beginning at two weeks. Full return to activity typically takes four to six weeks.

Is Stem Cell Therapy for Arthritis Safe?

Controlled trials of stem cell injections for knee arthritis have reported few serious adverse events in the short term. Shapiro et al. (2017), Emadedin et al. (2018), Freitag et al. (2019) and Matas et al. (2019) each reported no serious or major adverse events. The common side effects are a temporary flare of pain and swelling in the treated joint, plus soreness and bruising at the bone marrow or fat harvest site.

The larger risks come from unregulated products. A CDC investigation published in JAMA Network Open (Hartnett et al., 2021) traced bacterial infections in 20 patients who received umbilical cord blood-derived products marketed as stem cell treatment between 2017 and 2018. Any injection into a joint also carries a small risk of infection, so sterile technique and a documented product source matter.

Is stem cell therapy FDA approved for arthritis?

No. The FDA has not approved any stem cell product to treat osteoarthritis or rheumatoid arthritis. Same-day autologous procedures such as BMC can be offered under FDA rules for minimally manipulated tissue, but that is not the same as approval for arthritis. The FDA’s patient information on regenerative medicine therapies warns that unapproved products are being broadly marketed to consumers. The FDA status of stem cell treatments is covered in more detail separately.

How Stem Cell Injections Compare With Other Arthritis Injections

Most people considering stem cells for knee arthritis have already tried, or been offered, a cheaper injection. The 2019 American College of Rheumatology and Arthritis Foundation guideline (Kolasinski et al., 2020) rates each of them for knee osteoarthritis.

The guideline panel based its recommendation against stem cell and PRP injections on the heterogeneity and lack of standardization in available preparations, which makes it difficult to know what is being injected. That is a judgment about inconsistent products as much as about the cells themselves. The PRP treatment guide and the comparison of PRP vs stem cell therapy explain how the two biologic options differ.

Cost Breakdown

Cell Source	Typical Cost Range	Insurance Coverage	Evidence Grade
BMC (bone marrow concentrate)	$3,000 to $6,000	Rarely covered	Moderate
Adipose SVF (same-day)	$5,000 to $9,000	Not covered	Moderate
UC-MSC (umbilical cord)	$4,000 to $10,000+	Not covered	Emerging
Culture-expanded cells (trial only)	Variable / trial-sponsored	Not applicable	Emerging

Insurance does not currently cover any form of stem cell therapy for arthritis outside of clinical trials. This is unlikely to change in the near term. Some flexible spending accounts (FSAs) or health savings accounts (HSAs) can be used, but verify with your plan administrator.

Ask any clinic for a written quote that names the cell source, the imaging guidance, follow-up visits and the policy on repeat injections. A quote that bundles several injections or add-on products can make price comparisons misleading, and the stem cell therapy cost guide breaks down the common line items.

Who Is a Good Candidate

The ideal candidate for stem cell therapy for arthritis generally fits this profile: age 40 to 70, Kellgren-Lawrence grade 2 to 3 knee OA or moderate hip OA, has tried and failed physical therapy and cortisone injections, is not yet at the stage requiring joint replacement, and has realistic expectations.

Patients who are poor candidates include those with bone-on-bone disease (grade 4), active joint infection, uncontrolled autoimmune disease on high-dose immunosuppressants, active malignancy, or significant obesity (BMI over 40), as mechanical loading may overwhelm any biological repair.

For patients with osteoarthritis or chronic joint pain, stem cell therapy is one option within a broader treatment framework that should also address weight management, physical therapy, and activity modification. Cells alone rarely produce lasting results without addressing the biomechanical environment.

Recovery Timeline

Most patients experience a temporary flare of joint pain in the first one to three days post-injection, which is expected and reflects the inflammatory phase of healing. Significant improvement typically begins at six to eight weeks, though some patients report earlier changes.

Peak benefit is generally seen at six to twelve months. Data from longer follow-up studies suggest that results can persist for two years or more in responders, but repeat injections are sometimes needed at 18 to 24 months.

Some patients are non-responders, meaning they see no meaningful benefit, and published trials do not agree on how large that group is. This is a real consideration when evaluating whether to spend several thousand dollars on the procedure.

Red Flags When Evaluating Providers

Stem cell clinics vary enormously in quality, and some make claims that are not supported by science. Watch out for clinics that offer stem cell treatments for every condition imaginable, promise outcomes, use vague terms like “millions of stem cells” without specifying cell type or viability testing, or refuse to provide documentation of what is being injected.

Ask specifically: What cell source is being used? Is the product FDA-compliant for same-day use? Is the injection done under ultrasound guidance? What is the protocol for patients who do not respond? A qualified provider should answer these questions without hesitation.

Look for physicians with training in regenerative medicine, sports medicine, or orthopedics who can perform a proper musculoskeletal evaluation before recommending treatment. The injection should be part of a plan, not the whole plan.

To compare providers in your area, the directory of stem cell therapy clinics lists them by state and city, and clinics offering broader care appear under arthritis treatment clinics. Regenerated.com is free for patients, and listing order is not paid ranking. Featured slots are labeled and capped, and Verified means the clinic completed credential checks, not that it paid for placement. Inclusion in the directory is not an endorsement, so put the questions above to every clinic you contact.

Frequently asked questions

Does stem cell therapy work for knee arthritis?

Stem cell therapy for knee arthritis improves pain and function more than control treatments in pooled trial data, but the gains are modest and the trials are small. A 2017 PLOS ONE meta-analysis of 11 randomized trials and 582 patients found benefits at 12 to 24 months. One Mayo Clinic trial found bone marrow concentrate no better than saline. People with Kellgren-Lawrence grade 2 to 3 arthritis tend to do better than those with bone-on-bone disease.

Is stem cell therapy for hip arthritis worth it?

Stem cell therapy for hip arthritis has less evidence than for the knee, with mostly small uncontrolled studies, so its benefits are uncertain. The 2019 American College of Rheumatology guideline recommends against stem cell injections for hip osteoarthritis. People with mild to moderate hip OA who have not improved with physical therapy sometimes choose it after weighing the cost, and those with advanced joint collapse usually do better with hip replacement.

How long do stem cell injections last for arthritis?

Stem cell injections for arthritis, when they help, usually show improvement at six to eight weeks and peak benefit at six to twelve months. In responders, results can persist for two years or more, and some patients have a repeat injection at 18 to 24 months. Trials rarely follow patients beyond two years, so long-term durability is not well established, and some patients see no meaningful benefit at all.

Is stem cell therapy for arthritis safe?

Stem cell injections for arthritis have reported few serious adverse events in controlled knee trials, with temporary joint flare and harvest-site soreness as the common side effects. The serious risks come mostly from unregulated products: a CDC investigation (Hartnett et al., 2021) traced bacterial infections in 20 patients given umbilical cord blood-derived products marketed as stem cell treatment. Ask every clinic to document the product source and use imaging guidance.

Does insurance cover stem cell therapy for arthritis?

Insurance does not cover stem cell therapy for arthritis outside of clinical trials, so most patients pay cash. Typical prices run from about $3,000 to $6,000 for bone marrow concentrate to over $10,000 for some umbilical cord products. Some health savings accounts and flexible spending accounts can be used, but confirm with your plan administrator. Corticosteroid injections and, often, hyaluronic acid injections are covered alternatives for knee arthritis.

Can stem cells regrow cartilage in an arthritic knee?

Stem cells have not been shown to regrow meaningful cartilage in an arthritic knee in human trials. Mesenchymal stem cells appear to act mainly by releasing anti-inflammatory and growth signals rather than by becoming new cartilage. Some small studies, such as Freitag et al. (2019), reported MRI findings that suggested slower disease progression, but no trial has been large or long enough to confirm cartilage preservation.

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Related Reading

• Joint Pain: Causes, Diagnosis, and the Full Treatment Spectrum
• Osteoarthritis: What It Is, Why It Progresses, and How Regenerative Medicine Is Changing Treatment
• PRP Therapy: How Platelet-Rich Plasma Works and What It Treats
• Rheumatoid Arthritis
• Stem Cell Therapy: Types, Evidence, Cost, Risks, and What You Need to Know