Cartistem Research

Study Details

Procedure:

Patients underwent high tibial osteotomy (HTO). A surgery that realigns the leg to take weight off the damaged part of the knee.

At the same time, doctors implanted Cartistem into the damaged cartilage.

Cartistem contains 7.5 million donor stem cells per vial, mixed with a hyaluronic acid hydrogel to hold them in place.

Patients recovered with limited movement at first, gradually building up to full weight bearing.

Follow-up:

Doctors tracked progress for 2 years. At that point, when removing the surgical plate, they performed a “second-look” arthroscopy to check how the cartilage healed.

Cell Type Used:

Allogeneic (donor-derived) human umbilical cord blood mesenchymal stem cells.

Packaged as an “off-the-shelf” therapy by Medipost (Cartistem).

Results

Patients’ pain and function scores improved a lot over 2 years (WOMAC 57 → 28, pain score 66 → 26, physical health 28 → 55, mental health 41 → 63).

Cartilage damage shrank from about the size of a postage stamp (7.0 cm²) to almost nothing (0.16 cm²)

The quality of the cartilage improved from severely damaged (grade 4) to near normal (grade 1–2).

X-rays also showed arthritis improving (grade 3 → grade 2), and surgery corrected bowed legs (7.5° inward → almost straight).

The treatment was safe, with no complications or repeat surgeries.

How Cells Worked

• Sent healing signals that reduced inflammation and encouraged the body’s own repair.
• May have partially turned into cartilage-producing cells, but this wasn’t proven.

Overall, the improved cartilage is probably due to a combination of signaling effects + some direct repair.

What We Don’t Know

• The study was very small (10 patients).
• It only tracked results for 2 years – longer-term durability isn’t clear.
• There was no comparison group (no “HTO alone” patients), so we can’t say for sure how much of the effect came from Cartistem vs. surgery.
• They didn’t track where the stem cells went or whether they survived long-term.

Study Details

Design:

• Randomized into 2 groups
• Treatment group received umbilical cord blood–derived MSCs + 4% hyaluronic acid (Cartistem)
• Control group received microfracture surgery

Primary Outcome testing:

Doctors checked how well the knee cartilage had healed by doing a second-look arthroscopy (a small camera procedure) at 48 weeks. They graded the cartilage restoration using the ICRS scoring system, which measures how smooth, full, and well-integrated the new cartilage is.

Secondary Outcomes:

Pain (VAS), function (WOMAC, IKDC) and histologic cartilage quality

Long-term safety and symptom tracking up to 5 years

Procedure:

Surgical Method:

• Cartistem was delivered via mini-arthrotomy directly into 5-mm drill holes at the cartilage defect site.
• Microfracture group received standard arthroscopic treatment.

Cell Used:

• Allogeneic (donor) umbilical cord blood–derived mesenchymal stem cells (UCB-MSCs)
• Combined with 4% hyaluronic acid gel for structure and delivery

Dosage:

7.5 million MSCs per 1.5 mL of gel, injected directly into the defect site

The gel helped the cells stay in place and supported integration into the knee

Blinding:

Outcomes were assessed blindly by surgeons and histologists who did not know the treatment group

Patients and surgeons could not be fully blinded due to visible surgical differences

Cell Preparation:

Cells were grown in culture from screened donor cord blood

Tested for potency, sterility, mycoplasma, and endotoxins

Final dose was thawed and delivered on the day of surgery

Results:

Primary Outcome (Cartilage Restoration):

97.7% of patients who received the stem cell treatment (Cartistem) showed improvement of at least one cartilage grade on the ICRS scoring system at 48 weeks. Meaning their knee cartilage looked visibly healthier during the second-look arthroscopy compared to before treatment.

In comparison, only 71.7% of patients who had microfracture surgery (the control group) showed the same level of improvement

Biopsy Results (48 weeks):

• High levels of type II collagen
• The repaired cartilage contained abundant glycosaminoglycans, which are essential molecules that help healthy cartilage stay cushioned, hydrated, and flexible. A strong sign that the new tissue was high quality.
• The new cartilage had a strong, organized structure and was well-integrated with the surrounding tissue, meaning it blended in smoothly and looked more like natural, healthy cartilage.
• The new tissue that grew after treatment looked and behaved more like real, healthy cartilage (called hyaline cartilage) instead of weaker, less functional scar tissue (called fibrocartilage).

Functional Outcomes:

VAS Pain Score (0–100 scale)

Cartistem Group:

• Pain score dropped from 44 → 29.1

Microfracture Group:

• Pain score dropped only slightly from 44.6 → 43.5

P-value: 0.003 (statistically significant difference. Cartistem clearly better)

WOMAC Score

Cartistem Group:

• Score improved from 37.4 → 26.9

Microfracture Group:

• Score improved slightly from 40.4 → 36.2

P-value: 0.020 (statistically significant – Cartistem better)

IKDC Score

Cartistem Group:

• Score increased from 42.7 → 54.7

Microfracture Group:

• Score increased from 41.8 → 47.1

P-value: 0.007 (statistically significant – Cartistem better)

Across all three major measures of knee pain and function Cartistem showed significantly greater improvements than standard microfracture surgery

Improvements were maintained at 5 years in Cartistem group

Microfracture patients’ gains faded after year 3

MRI Not Used for Primary Imaging:

Assessment was done via second-look arthroscopy and tissue biopsy

No MRI-based cartilage volume metrics included

Adverse Events

• No immune reactions or rejection (despite donor cells)
• No major safety issues
• Serious events (e.g., knee replacement) were rare and similar between groups

How Cells Worked

The UCB-MSCs helped by sending out anti-inflammatory and healing signals to the surrounding joint tissue (paracrine effect).

There was no evidence the cells directly turned into cartilage.

Instead, they likely stimulated the patient’s own repair processes and improved the environment for regeneration.

What We Don’t Know

• Long-term cartilage durability beyond 5 years
• Whether non-surgical delivery methods (e.g., injection) would be as effective

Conclusion

This study shows that Cartistem can safely restore cartilage structure, improve pain + knee function and help avoid further knee damage in older adults with serious joint defects.

While the cells didn’t directly become new cartilage, they created a powerful healing environment, leading to better outcomes than microfracture and those results lasted 5 years.

Study Details

Participants:

54 patients (60 knees) with advanced medial knee OA

Divided into two treatment groups:

• Cartistem group: 27 knees
• Microdrilling group: 33 knees

All had:

• Near or full-thickness cartilage damage (ICRS Grade 3–4).
• – Grade 3: Severe cartilage damage with deep lesions but not yet fully exposed bone
• – Grade 4: means the cartilage is completely worn away, exposing the underlying bone. A condition often described as “bone-on-bone.”

These patients had also failed to improve with conservative (non-surgical) treatments.

The patient’s legs were bowed inward (called varus alignment), which puts too much pressure on the inner (medial) part of the knee.

– To fix this, surgeons performed a procedure called High Tibial Osteotomy (HTO) to realign the leg, shifting weight away from the damaged area of the joint.

All patients had arthritis only on the inner side of the knee (medial compartment), and the outer side (lateral compartment) was still healthy.

Treatment Design:

• Cartistem group: Cartistem implanted during HTO
• Control group: Microdrilling during HTO

All patients received second-look arthroscopy ~12 months post-op. (a surgical procedure where a doctor inserts a tiny camera into the knee to look inside and examine the cartilage, bone, and other tissues.)

Results

Primary Outcome:

Cartilage Quality, evaluated by ICRS CRA score during second-look arthroscopy.

– ICRS CRA score is a way for doctors to grade how good the new cartilage looks when they check the knee with a camera. Higher scores mean smoother, fuller, better-healed cartilage.

Cartistem® group: 9.41

Microdrilling group: 7.94

P = .021

This means more complete, better-integrated cartilage was visible in the Cartistem group.

Other Outcomes

Pain dropped from 48 → 15.2

(VAS: In the Cartistem group, pain scores fell from 48 to 15.2 out of 100 at 24 months.)

In contrast, the microdrilling group improved from 52.2 → 28.6.

(P = 0.016 — statistically significant)

Function improved from 36.6 → 58.5

(IKDC: In the Cartistem group, knee function scores rose from 36.6 to 58.5 out of 100.)

This was significantly better than the microdrilling group (which improved from 35.8 → 50.3).

(P = 0.038)

Patients reported better walking, stair climbing, and daily mobility.

No significant difference in MRI cartilage appearance

(MOCART 2.0 scores: Cartistem group averaged 53.7; microdrilling group 53.04 on a 100-point scale)

(P = 0.85 — not statistically significant)

This suggests both groups had a similar amount of visible cartilage fill on MRI after one year.

Anterior lesions healed best

Patients with anterior cartilage damage (front part of the knee) showed higher cartilage scores than those with middle or posterior lesions. Especially with Cartistem.

No major safety concerns

No infections, allergic reactions, or serious adverse events were reported in either group.

The Cartistem product used was allogeneic (donor-derived) but showed no immune complications.

How the Cells Worked

While the researchers did not directly test how the cells functioned inside the knee, they highlighted several important characteristics:

• Low immunogenicity: Cartistem is made from donor cells, but it has a low risk of triggering an immune response or rejection.
• Lab expansion and consistency: The cells can be easily grown in the lab to therapeutic doses and prepared as an off-the-shelf product.
• Effective even in older patients: Unlike stem cells from a person’s own body Cartistem stem cells retain high regenerative potential regardless of patient age.

However, the study did not specify whether the cells turned into cartilage themselves (a process called differentiation) or worked by sending out healing and anti-inflammatory signals

Conclusion

This study found that in older adults with arthritis on the inner side of the knee and bowed-leg alignment, Cartistem led to better cartilage healing, less pain, and improved knee function than microdrilling when both were combined with high tibial osteotomy (HTO).

Although both treatments helped, Cartistem provided significantly better results, especially in:

• Patient-reported pain and mobility
• Cartilage quality seen during follow-up knee camera exams

The MRI scans showed similar amounts of cartilage in both groups, but Cartistem patients had smoother, more natural-looking tissue under direct inspection.

The results suggest that Cartistem, when used with HTO, may be a more effective option than microdrilling for patients with serious medial knee osteoarthritis and bow-legged alignment.

Study Details

Treatment Procedure

A single surgical implantation of Cartistem into the defect site:

• Surgeons created 4 mm-deep holes in damaged cartilage using an arthroscopic burr
• The procedure used Cartistem, a product containing 7.5 million stem cells per 1.5 mL

Cell Type Used: CartiStem:

• Umbilical Cord Derived Mesenchymal Stem Cells
• Mixed with hyaluronic acid at the time of surgery

How Cells Were Prepared

Cartistem is produced by Medipost, a Korean biotech company:

• Umbilical cord blood was collected with maternal consent and processed in a GMP facility
• Cells were expanded and cryopreserved, then thawed and injected fresh on surgery day

The dose was personalized based on the size of the cartilage damage, with about 5 million stem cells per milliliter. For every 1 cm² of damaged cartilage, doctors injected 0.5 mL of the stem cell mixture, so larger areas received more cells.

• For example, a 4 cm² defect would receive 2 mL, or about 10 million stem cells in total.

Cell identity verified per regulatory standards, though ISCT surface marker data were not reported

Full Results and Success Rates

Pain dropped from 7.0 → 2.0 (VAS: After treatments, patients reported their pain as 2 out 10)

Function improved from 32.5 → 61.2 (IKDC: Function scores nearly doubled. Rising from 32.5 to 61.2 (out of 100) on the IKDC scale. Meaning patients could walk, climb stairs, and move more easily after treatment.)

WOMAC scores improved by 65%, on average. (This means that, on average, patients’ symptoms decreased by 65% compared to where they started.)

All improvements were statistically significant (P < 0.001)

Effect was consistent across all age, BMI, lesion size, and lesion count groups

Trochlear lesions (front part of the knee) had slightly better outcomes than medial femoral condyle ones (inner part of the knee joint)

No infections, allergic reactions, or serious adverse events reported

How Cartilage Was Assessed

34 of the 128 patients agreed to post-op MRIs:

MRI scans showed that damaged cartilage areas were gradually filling in with new tissue. On a 100-point scale, healing improved from a score of 30.6 to 55.4 over a year. Meaning most patients had visible cartilage regrowth, even if it wasn’t complete.

This implies visible defect filling, but:

• No histological biopsy was done
• The study did not report how many patients had full vs. partial coverage
• No evaluation of cartilage strength or type (e.g., hyaline vs. fibrocartilage)

How Cells Might Have Worked

This is what the researchers concluded about how these cells worked:

It’s not known whether hUCB-MSCs repair cartilage by turning into new cells or by sending signals to help healing.

However, we believe these stem cells are more useful than other types because of their advantages.

What We Don’t Know

• No long-term data past 2 years
• No detailed analysis of cartilage composition or durability
• Only 25% of patients underwent MRI, and MOCART subscores (e.g., surface, signal, integration) were not disclosed