CARTISTEM Enters U.S. Phase 3: Cord Blood Stem Cells for Knee Cartilage

If you have knee arthritis, you have probably heard some version of this line: "In Korea they've been doing stem cells for knees for years."

For one product, that is true.

It is called CARTISTEM. A Korean company, MEDIPOST, brought it to market in South Korea in 2012. The company says more than 36,000 patients there have received it since.

In July 2026, the first American patient got it too. Not at a cash-pay clinic. In a Phase 3 trial, at Orthopedic Centers of Colorado (MEDIPOST, July 8, 2026).

That is real news. It is also easy to twist. Someone will read it and say "see, stem cells for knees are proven." They are not. Not this one, not yet. And not the shot your neighbor got either.

So let's go through it plainly. What CARTISTEM is. What the Korean trial actually found. What the U.S. trial is testing. And what any of it has to do with you.

What Is CARTISTEM?

CARTISTEM is a combination product. Two parts, mixed in the operating room.

• Cells: allogeneic (donor) mesenchymal stem cells grown from human umbilical cord blood. In the U.S. trial, one vial holds about 7.5 million cells in 1.5 mL.
• Gel: 60 mg of sodium hyaluronate, mixed with the cells to form a thick 4% gel that a surgeon can pack into place.

Here is the part most headlines skip. CARTISTEM is not injected into the knee like a cortisone shot.

In the Korean Phase 3 trial, surgeons first looked inside the knee with a scope. Then they made a small open incision beside the kneecap tendon, drilled a series of 5 mm holes into the bone under the damaged cartilage, and filled those holes with the cell gel. Then came rehab. Patients in the CARTISTEM group were told to stay off the leg, on crutches or a walker, for the first 12 weeks, followed by 4 weeks of partial weight-bearing (Lim et al., 2021).

That is knee surgery with a four-month recovery. Keep that in mind any time someone uses CARTISTEM to sell a 20-minute injection.

Cord Blood Is Not Cord Tissue

This one trips people up, so let's be precise.

Umbilical cord blood is the blood left in the cord and placenta after a baby is born. It is the same material families pay to store at cord blood banks. MSCs can be isolated from it and grown in a lab.

Wharton's Jelly is the gel-like connective tissue inside the cord itself. MSCs can be isolated from that too.

Same cord. Different starting material. Different processing. In CARTISTEM's case, the published paper describes cells taken from donor cord blood, separated, and then expanded over multiple passages in a GMP manufacturing facility before being frozen and released with potency, sterility, and other testing (Lim et al., 2021).

So when you see "umbilical cord stem cells" in a headline about CARTISTEM, read it as "umbilical cord blood-derived MSCs from one specific manufacturer." The data belong to that product. They do not carry over to a Wharton's Jelly product, a fat-derived product, or a bone marrow product. Including ours.

What Did the Korean Phase 3 Trial Show?

The main peer-reviewed paper is Lim and colleagues in the Orthopaedic Journal of Sports Medicine, 2021 (doi:10.1177/2325967120973052). It covers a randomized Phase 3 trial run at 10 Korean hospitals from 2009 to 2011, plus an extended follow-up out to five years.

Who was in it

114 patients were randomized. Average age 55.9. About two-thirds were women. Every patient had a full-thickness cartilage defect (ICRS grade 4) on the thigh-bone side of the knee, 2 to 9 cm² in size, confirmed by arthroscopy. These were not young athletes with a small ding. In the CARTISTEM group, 95% had osteoarthritis, and most defects were "bipolar," meaning damage on both sides of the joint.

Half got CARTISTEM. Half got microfracture, a common procedure where the surgeon pokes small holes in the bone so marrow can seep up and form repair tissue. 89 patients finished the one-year trial. 73 joined the five-year follow-up.

The primary result: what the cartilage looked like

At 48 weeks, every patient had a second-look arthroscopy. Evaluators who did not know which treatment a patient got graded the repair.

• Improved by at least one ICRS grade: 97.7% of the CARTISTEM group (42 of 43) vs 71.7% of the microfracture group (33 of 46). P = .001.
• Tissue biopsies: the overall histology score was also better in the CARTISTEM group (P = .036).
• By age and defect size: microfracture results dropped off in patients 50 and older and in larger defects. CARTISTEM results did not drop off the same way in this study.

The part people leave out: pain and function at one year

At 48 weeks, pain (VAS), WOMAC, and IKDC scores improved in both groups. But they were not significantly different between the groups.

Read that again. At one year, the knee looked better on a scope in the CARTISTEM group. Patients did not report feeling significantly better than the microfracture patients.

The gap showed up later. In the 3- to 5-year follow-up, the CARTISTEM group held its gains, while the microfracture group's pain and WOMAC scores slid back. Pain was significantly better in the CARTISTEM group at 60 months. WOMAC and IKDC were significantly better at 36 and 60 months.

Safety in that trial

The authors reported no differences between groups in overall adverse events. In the first 48 weeks, the CARTISTEM group had three serious adverse events: implant-site pain, pneumonia, and one kidney cancer. Investigators judged only the implant-site pain as probably related to treatment, which they put down to the open incision. In the long-term follow-up, one CARTISTEM patient died of a heart attack at 41 months; that was not considered treatment-related. By five years, 2 knee replacements and 1 osteotomy had been done in the CARTISTEM group, versus 3 knee replacements, 1 osteotomy, and 1 meniscectomy in the microfracture group. That difference was not significant.

What About Japan?

In May 2026, MEDIPOST announced that its Japan Phase 3 trial met all primary and secondary endpoints (MEDIPOST, May 14, 2026). Per the company: 13 sites, 130 participants enrolled, 52 weeks of follow-up, and a hyaluronic acid control group. The release lists 59 patients in the CARTISTEM group and 61 in the control group. It reports co-primary results on WOMAC (p < 0.0001) and ICRS cartilage grade (p = 0.0002) in CARTISTEM's favor. MEDIPOST says it plans to file in Japan in the second half of 2026 and is targeting approval by the end of 2027.

Two cautions. This is a company press release, not a peer-reviewed paper. And the group sizes listed (59 plus 61) do not add up to the 130 enrolled, which a full publication should explain. Until then, treat the Japan numbers as a headline, not a dataset.

What the U.S. Phase 3 Trial Is Testing

MEDIPOST has been at this in the U.S. for a while. A small 12-person Phase 1/2 safety study (NCT01733186) wrapped up in 2017. The new trial is the big one.

It is registered as NCT07339111 (CARTISTEM23-01). Here is what the registry says as of October 2026:

• Design: randomized, multicenter, double-blind. Both the participant and the outcomes assessor are masked.
• Arms: CARTISTEM plus debridement vs debridement alone. Debridement means cleaning up unstable cartilage around the lesion. Both groups get knee surgery.
• Size: an estimated 300 patients.
• Who qualifies (in short): ages 18 to 75, knee OA at Kellgren-Lawrence grade 2 or 3, femoral cartilage defects totaling 2 to 9 cm², BMI of 35 or under, and at least three months of failed conservative care. The full list of exclusions is long.
• Primary endpoints: change in pain (VAS) and WOMAC function at 24 months.
• Secondary: MRI measures of cartilage repair and cartilage damage.
• Timeline: started March 11, 2026. Estimated primary completion June 30, 2029.
• Status: recruiting, with 31 U.S. sites listed, including Salt Lake City, two sites in Colorado, and several in Arizona and California.

This design fixes the biggest weakness of the Korean trial. Both groups get surgery, so patients can be kept blind to which one they received. And the primary endpoint is what you actually care about: does your knee hurt less and work better two years later.

The FDA deal, in plain English

In June 2026, MEDIPOST said the FDA agreed that this single pivotal trial, backed by the Korea and Japan Phase 3 data and Korean real-world data on about 550 patients treated at least three years earlier, can support a future Biologics License Application (MEDIPOST, June 2026). Korean press reported the plan cut total enrollment from 600 to 300 (Seoul Economic Daily, June 4, 2026).

Notice what the FDA did not do. It did not approve anything. It agreed on what evidence MEDIPOST has to bring. MEDIPOST's own release says the therapy is investigational, not FDA-approved, and that its clinical benefit "has not yet been established."

That is the BLA path. It is the same road Ryoncil took before it became the first FDA-approved MSC therapy. Slow, expensive, and the only route to an FDA-approved stem cell drug.

CARTISTEM vs. Clinic Knee Injections vs. Microfracture

Three very different things get lumped together as "regenerative knee treatment." Here is how they line up.

Does This Mean Stem Cell Knee Injections Work?

No. It doesn't answer that question at all.

CARTISTEM is a specific product, made a specific way, delivered by surgery into a specific kind of defect. Clinic injections are a different product, a different delivery method, and usually a different cell source.

And in September 2026, the American College of Rheumatology put it bluntly in its updated osteoarthritis guideline: "In people with knee and hip OA, we strongly recommend against stem cell injections" (ACR 2026 guideline summary). We broke that down, along with the newest injection trials, in our post on what the 2026 knee osteoarthritis trials actually show.

CARTISTEM doesn't get a pass on that logic either. It is still unproven in the U.S. The point of a 300-patient, double-blind, two-year trial is to find out. If it succeeds, that is evidence for CARTISTEM. Not for every vial with "umbilical cord" on the label.

Where The Stem Cell Club Fits

Straight answer: we do not offer CARTISTEM. We do not use cord blood MSCs. We do not do cartilage implant surgery.

We offer umbilical cord Wharton's Jelly MSC options sourced from an FDA-registered U.S. lab. Registration covers facility and manufacturing standards. It is not FDA approval of the product. Our offerings are not FDA-approved to diagnose, treat, cure, or prevent any disease, including knee osteoarthritis.

We won't borrow CARTISTEM's data to sell you anything. Different cells, different product, different procedure.

If CARTISTEM is what you want, the only U.S. route right now is the trial. Take NCT07339111 to an orthopedic surgeon and ask whether you fit the criteria. That is a legitimate option, and we'd rather point you there than pretend we are something we're not.

If you are weighing other options, read our plain-English guide to stem cell therapy and FDA approval, our page on stem cell therapy side effects, and our piece on cell count vs viability before you book anything, anywhere.

Questions to Ask Before Any Stem Cell Knee Procedure

• Which cells, from where? Cord blood, cord tissue, fat, or bone marrow? They are not interchangeable.
• Is this the product in the study you're quoting? If a clinic cites Korean CARTISTEM data, ask if they are using CARTISTEM. They aren't.
• Injection or surgery? CARTISTEM's data come from surgical implantation into drilled defects, followed by months of rehab.
• What is the FDA status of this exact product? "Our lab is registered" and "our product is approved" are different sentences.
• What did the comparison group get? Placebo, hyaluronic acid, or microfracture? Each one tells you something different.
• Who paid for the study, and was it peer-reviewed? A press release is a starting point, not proof.

Frequently Asked Questions