Knee cartilage injuries are a difficult clinical problem because this tissue cannot repair itself. A phase I and II study directly compared two cell-based therapies: umbilical cord mesenchymal stem cells and the patient’s own bone marrow aspirate concentrate. The group treated with cord cells reported earlier pain relief and higher functional scores at 6 and 12 months.
Why knee cartilage doesn’t heal
Articular cartilage has one feature that makes it a complex orthopedic problem: it has no blood vessels. Without a direct vascular supply, its capacity for self-regeneration is very limited.
An injury that would heal spontaneously in another tissue tends instead to persist and enlarge in knee cartilage. Over time it progresses toward osteoarthritis and, in more advanced cases, toward joint replacement.
Cell-based therapies have entered this picture precisely because they aim to rebuild the tissue rather than simply manage pain. We discuss this more broadly in our deep dive on regenerative medicine and perinatal stem cells.
The study: a head-to-head comparison
The research, structured as a phase I feasibility study followed by a randomized, controlled phase II, compared two approaches:
- UC-MSC — mesenchymal stem cells from umbilical cord tissue (Chondrocell-EX product), administered as a single intra-articular injection of 25-30 million cells combined with hyaluronic acid;
- BMAC — bone marrow aspirate concentrate, meaning cells taken from the patient’s own bone marrow, combined with a scaffold.
The procedural difference matters as much as the biological one. The intra-articular injection is an outpatient procedure; bone marrow harvesting, on the other hand, requires an additional procedure on the patient, with the time and discomfort that entails.
Clinical results on knee cartilage
Pain decreases sooner. Patients treated with UC-MSC reported a significant reduction in pain as early as one month after treatment. In the BMAC group, significant improvement only appeared after three months.
Function is better in the medium term. Scores for physical function, joint stiffness, and quality of life were higher in the cord-derived cell group at 6 and 12 months.
It also works in difficult cases. Cord stem cells produced good results even in older patients and in those with more extensive and severe knee cartilage lesions — situations where adult autologous cell therapies typically perform less well.
Not just symptoms: the quality of the regenerated tissue
Perhaps the most interesting finding doesn’t concern pain but the structure of the rebuilt tissue.
Histological and arthroscopic analyses documented the formation of hyaline-type cartilage — the functionally competent form of cartilage tissue — in place of the fibrocartilage typically formed with many other repair approaches.
The distinction is far from academic. Fibrocartilage has inferior mechanical properties and degrades more quickly under load: achieving hyaline cartilage means aiming for a repair built to last, not just temporary relief.
Why “younger” cells perform better
The authors link the observed advantage to the very origin of the cells.
Umbilical cord mesenchymal cells come from healthy perinatal tissue: they haven’t accumulated the damage linked to age, environmental exposure, or prior conditions. Cells taken from an adult patient, by contrast, often belong to the very person suffering from a degenerative condition — and carry its marks.
Added to this is a higher proliferative capacity and low immunogenicity, which reduces the likelihood that the recipient’s immune system will recognize them as foreign.
Safety and limitations of the study
The safety profile was favorable: no serious adverse events. The initial issues reported, mainly mild joint swelling, resolved spontaneously.
However, the typical limitations of a phase I/II study remain: a limited sample size and a still-short time horizon. Multi-year follow-up will be needed to establish how long the benefit to knee cartilage is maintained. Studies currently underway in this research area can be found on ClinicalTrials.gov.
Important note: The applications described belong to the field of clinical research and do not constitute approved therapies available in current practice. No information reported here should be understood as medical advice. For any clinical evaluation, please consult your physician.
Why SSCB follows these studies
This work concerns umbilical cord tissue, not cord blood: two different sources, with cell populations and potential applications that do not overlap. This is a distinction we explain in our comparison of cord blood, cord tissue, and placenta.
SSCB stores both sources, as well as placenta, and is the only Swiss biobank accredited by FACT-NetCord, the international standard specific to cord blood banks. We’ve dedicated a deep dive to process standards in our piece on certifications and accreditations.
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Source: Md Yusoff BAH, Mohamad N, Chin SP, et al. Cytopeutics umbilical cord-derived mesenchymal stem cells are associated with earlier clinical improvement compared to bone marrow aspirate concentrate with scaffold in knee cartilage injury: A Phase 1 feasibility and Phase 2 randomized controlled trial. Med J Malaysia. 2026;81(2):234-245.
