A new chapter in stem cell treatment for knee arthritis is underway in the United States. MEDIPOST Inc. has announced that the first U.S. participant has been treated in a Phase 3 clinical trial of CARTISTEM® — an investigational allogeneic mesenchymal stem cell (MSC) therapy derived from umbilical cord blood — in adults with symptomatic cartilage defects due to knee osteoarthritis.

The first procedure was performed at Orthopedic Centers of Colorado by Dr. Justin Newman, marking the start of a pivotal U.S. trial that the FDA authorized based on prior Phase 3 data from South Korea and Japan, along with real-world evidence from more than a decade of clinical use overseas.

What CARTISTEM Is — and Why It's Different

CARTISTEM is an allogeneic cell therapy, meaning the cells come from a donor source rather than from the patient. Specifically, it is composed of mesenchymal stem cells (MSCs) isolated from umbilical cord blood. MSCs are of interest in orthopedic research because they can modulate inflammation and, in some studies, appear to support cartilage repair.

CARTISTEM has been commercially available in South Korea since 2012 for osteoarthritis-related cartilage defects. The current U.S. Phase 3 trial is designed to generate the data MEDIPOST needs to seek approval from the U.S. Food and Drug Administration through a Biologics License Application (BLA).

How this differs from what many patients have tried already:

• Not a corticosteroid or gel injection. Steroid and hyaluronic acid injections aim to reduce pain and inflammation temporarily; CARTISTEM is being investigated as a cell-based intervention targeting the underlying cartilage.
• Not autologous PRP or "your own" stem cells. Because the cells come from a screened umbilical cord source, dosing and cell quality are standardized rather than dependent on the patient's own tissue.
• A one-time procedure rather than an ongoing regimen. The therapy is delivered during a single surgical procedure, similar in setting to other cartilage procedures.

Who the Trial Is Studying

The Phase 3 study is enrolling adults ages 18–75 with symptomatic knee osteoarthritis and cartilage lesions. According to the CDC and prior published estimates, more than 32 million U.S. adults live with knee osteoarthritis, and many of them fall into a difficult middle ground: too symptomatic to manage with conservative care alone, but not yet a candidate for — or not ready for — a total knee replacement.

Prominent orthopedic surgeons have publicly welcomed the effort. Dr. Brian Cole of Rush University noted that the research "gives us a meaningful opportunity to investigate whether a regenerative approach can help address" the treatment gap between conservative care and joint replacement. Dr. Andreas Gomoll of the Hospital for Special Surgery framed the study as an effort to "demonstrate efficacy of a MSC therapy in adults with knee osteoarthritis."

Why This News Matters to Patients in San Diego

Horizon Clinical Research is not a site for this particular MEDIPOST study. But the news matters to our community for two reasons.

First, it reflects a broader shift. After many years of incremental change in knee osteoarthritis treatment, the pipeline of investigational cell-based, biologic, and cartilage-preservation therapies is finally advancing through late-stage clinical research. Patients who thought their only options were more injections or eventual replacement now have a growing set of research pathways to consider.

Second, similar research is happening close to home. Horizon actively enrolls San Diego patients into FDA-regulated orthopedic clinical trials, including studies focused on knee pain, knee osteoarthritis, and cartilage preservation. If you are dealing with persistent knee pain and want to understand whether a current study — ours or another — may be appropriate for you, our research team is happy to help you sort through the options.

What "Phase 3" Actually Means

Phase 3 is the last stage of clinical trials before a therapy can be submitted to the FDA for approval. It typically involves larger numbers of patients across multiple sites, and it is designed to answer two questions with statistical rigor: does the therapy work? and is it safe enough in a broader population?

Being a Phase 3 participant in a well-designed trial often means:

• Careful screening to make sure the study is a good fit medically
• Detailed clinical evaluations and imaging
• Close follow-up with the research team throughout the study
• Study-related care at no cost to qualified participants

It also means participating in the process that decides whether a therapy becomes available to future patients.

Next Steps for Interested Patients

If you have knee pain or a diagnosis of knee osteoarthritis and you are interested in learning what clinical research options exist — either the MEDIPOST trial at another site or one of Horizon's current studies in San Diego — a short, no-obligation screening conversation is the fastest way to find out.

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