When Poor Circulation Becomes Serious
Critical limb ischemia, often called CLI, is a severe form of poor blood flow in the legs or feet. It can happen when arteries become blocked or damaged, preventing enough oxygen-rich blood from reaching the tissues.
For patients, this can lead to serious symptoms such as:
- Pain while resting
- Non-healing wounds or ulcers
- Tissue damage
- Difficulty walking
- Increased risk of amputation
Standard treatments may include procedures to restore blood flow, such as vascular surgery or endovascular treatment. However, some patients are not good candidates for these options because of the condition of their blood vessels or other health risks. For these “no-option” patients, researchers are exploring new ways to support circulation, tissue health, and healing.
Why Placenta-Derived MSCs Are Being Explored
Mesenchymal stem cells, or MSCs, are being studied in regenerative medicine because they release helpful signals that may support repair, inflammation balance, and blood vessel growth.
This study focused on placenta-derived MSCs, also called P-MSCs. The placenta is naturally rich in blood vessels and biological signals, which makes it an interesting source for studying therapies related to circulation and tissue repair.
Rather than acting as a simple replacement for damaged tissue, MSCs may work more like “messenger cells.” They release signals that communicate with nearby cells and may help the body create a healthier environment for healing.
A Look Inside the Clinical Trial
This was a phase I dose-escalation clinical trial, which means it was an early-stage human study mainly designed to evaluate safety and tolerability.
The study enrolled patients with critical limb ischemia who were not eligible for standard surgical or endovascular procedures. Participants received placenta-derived MSC injections directly into the muscles of the affected limb.
The researchers tested two dose levels:
- 20 million cells
- 60 million cells
Patients received two treatments, spaced about two months apart. They were then followed for six months to monitor safety and early signs of potential benefit.
The main goal was to see whether the treatment caused any serious treatment-related side effects. Researchers also looked at pain, walking ability, wound healing, inflammation markers, blood flow measures, and whether patients could avoid major amputation.
What the Researchers Found
The study reported encouraging safety findings. Placenta-derived MSC treatment was generally well tolerated, including at the highest tested dose of 60 million cells.
The researchers did not report dose-limiting toxicities or treatment-related adverse events that required stopping therapy. Some patients experienced temporary side effects, such as diarrhea or itching, but these improved.
The study also found several early signs of possible benefit. Patients showed meaningful improvement in rest pain, which is one of the most difficult symptoms of critical limb ischemia. Pain scores improved significantly over the six-month follow-up period.
Walking ability also improved in patients who were able to complete treadmill testing. This is important because walking distance can reflect how well the limb is functioning in daily life.
Researchers also noted wound healing improvements in some patients and reported that minor amputations were performed instead of major amputations when needed.
Inflammation and Blood Flow Support
One interesting part of this study was the effect on inflammation. After treatment, researchers observed a significant decrease in two inflammatory markers: IL-1 and IFN-γ. These markers are involved in inflammatory activity, which can affect tissue health and healing.
The study also looked at whether new blood vessel growth could be seen on angiography, an imaging test used to view blood vessels. Some improvement in collateral vessel formation was observed, but the imaging results were not strong enough to clearly confirm new small vessel growth across the group. In simpler terms, the treatment appeared to support pain relief, walking ability, and inflammation balance, while the blood vessel imaging results were more limited and need further study.
Why This Study Matters
This study is meaningful because critical limb ischemia can be extremely difficult to treat, especially for patients who do not have good surgical options. For these patients, even small improvements in pain, walking, wound healing, or limb preservation can be important.
The research also adds to the growing interest in placenta-derived MSCs as a potential regenerative medicine approach. Their ability to release repair-supportive and immune-balancing signals may make them useful for conditions where blood flow, inflammation, and tissue damage overlap.
What Comes Next
Because this was a small phase I trial, the results should be viewed as an early step. The main purpose was safety, not proving effectiveness. Larger randomized clinical trials will be needed to better understand how well placenta-derived MSCs work, how long benefits may last, and which patients are most likely to respond.
Longer follow-up will also be important to better evaluate wound healing, blood flow, limb preservation, and long-term safety.
Main Takeaway
This phase I clinical trial found that intramuscular placenta-derived MSC treatment was generally well tolerated in patients with critical limb ischemia who had limited treatment options. The study also reported improvements in rest pain, walking distance, inflammatory markers, and some wound-related outcomes.
While more research is needed, the findings support continued study of placenta-derived MSCs as a regenerative medicine approach for circulation support, inflammation balance, and tissue healing in severe limb ischemia.
Source
Shirbaghaee Z, Heidari Keshel S, Rasouli M, Valizadeh M, Hashemi Nazari SS, Hassani M, Soleimani M. Report of a phase 1 clinical trial for safety assessment of human placental mesenchymal stem cells therapy in patients with critical limb ischemia (CLI). Stem Cell Research & Therapy. 2023 Jul 5;14:174. doi: 10.1186/s13287-023-03390-9. PMID: 37408043; PMCID: PMC10324209. https://link.springer.com/article/10.1186/s13287-023-03390-9
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