How safe is stem cell therapy for spinal cord injury?

In the CELLTOP phase 1 trial from Mayo Clinic, published in Nature Communications in 2024, ten adults with traumatic SCI received MSCs delivered into the spinal fluid, and no serious adverse events were attributed to the treatment; headache and musculoskeletal pain were common but manageable. Across many conditions, intravenous (IV) MSCs are most consistently associated with a temporary fever, without increased infection, blood clots, cancer or death in controlled trials. For people living with SCI, however, the most important safety risks often come not from the cells themselves but from the realities of travel and medical care with paralysis: autonomic dysreflexia, pressure injuries, urinary infections, blood clots, blood pressure changes and breathing problems in higher injuries. At Stem Cell Mexico, SCI protocols use allogeneic MSCs from umbilical cord tissue, with nursing care adapted to SCI needs and careful planning of every step.

This guide explains what is known about safety, the SCI-specific risks to plan for and how they are reduced.

What the evidence shows

Intrathecal MSCs in SCI

In CELLTOP, each participant received a single dose of 100 million autologous fat-derived MSCs by lumbar puncture. The primary safety endpoint was met. Eight of ten participants had headache and nine had musculoskeletal pain, generally managed with over-the-counter medications. MRI showed clumping of nerve roots at the lower end of the spinal canal in several participants without related symptoms, a finding the investigators continue to follow. Seven participants improved on the ASIA Impairment Scale, although the small, uncontrolled design means natural recovery cannot be excluded.

IV umbilical cord MSCs across conditions

A 2026 systematic review in Stem Cells Translational Medicine (Hum and colleagues) of 42 randomized trials with 2,280 patients receiving intravascular umbilical cord MSCs found more temporary fever, but no signals of harm for infection, thrombosis, malignancy, abnormal tissue formation or death, while recommending continued long-term monitoring.

What this means

Early SCI studies and broader MSC data suggest the cells are generally well tolerated. Because SCI affects many body systems, individualized planning is essential.

Understanding fever after an infusion with SCI

Temporary fever is the most common side effect of IV MSCs, but in people with SCI it can be more difficult to interpret and tolerate. Below the injury level, the body may not sweat or shiver normally, so temperature can rise or fall more than expected, and fever can be a trigger for autonomic dysreflexia in higher injuries. Infections that commonly affect people with SCI, such as urinary tract infections or infected pressure areas, can also cause fever and must not be mistaken for a simple reaction to the cells. During observation, nurses monitor temperature, blood pressure and symptoms closely, use cooling or warming measures as needed and look for other causes before attributing a fever to the treatment.

Safety by route

• Intravenous infusion: minimally invasive; temporary fever, headache or fatigue are the most common effects.
• Intrathecal (lumbar puncture): headache, back pain and, rarely, infection; requires positioning that must be adapted for people with paralysis and spasticity.
• Direct surgical implantation: used only in research, with surgical risks.

The route recommended for you, and its specific risks, should be explained before treatment.

SCI-specific safety considerations

Autonomic dysreflexia

In injuries at or above the sixth thoracic level (T6), a trigger below the injury, such as a full bladder, constipation, a pressure area, tight clothing or a painful procedure, can cause a sudden, dangerous rise in blood pressure with headache, flushing and sweating. Staff must know how to recognize it and remove the trigger immediately. Patients and caregivers should share their usual signs and management plan.

Pressure injuries

Long travel, unfamiliar beds and reduced repositioning increase the risk of skin breakdown. Pressure-relieving cushions, regular turning and skin checks are essential.

Bladder and bowel care

Intermittent catheterization schedules, indwelling catheters and bowel programs must be continued on time. Urinary tract infections are common and are a reason to postpone treatment if active.

Blood clots

Reduced mobility increases the risk of deep vein thrombosis, especially in the first years after injury and during long trips. Hydration, movement where possible and, when prescribed, preventive medication are considered.

Blood pressure and temperature regulation

People with higher injuries often have low blood pressure and difficulty regulating body temperature. Fever after an infusion may be harder to tolerate, and cooling or warming measures may be needed.

Breathing

Cervical and high thoracic injuries can weaken breathing and coughing. Sedation is used cautiously, and respiratory status is monitored.

Spasticity and pain

Procedures and positioning can trigger spasms. Usual antispasticity medications are continued.

Crossing the border and traveling with SCI

For many patients, getting to the clinic is the most demanding part of treatment. Long waits in vehicles or at border crossings mean prolonged sitting without pressure relief, delayed catheterization and limited bathroom access. Planning reduces these risks: schedule crossings at less busy times, use wheelchair-accessible transportation with space for equipment, carry catheter supplies, medications and a change of clothes in an easily reachable bag, and plan pressure relief at regular intervals. Bring documentation of your medications and medical supplies. A caregiver who knows your routines makes travel safer and more comfortable, and the coordination team can help organize timing and accessible transport.

How we reduce risk

• Detailed review: injury level, AIS grade, time since injury, imaging, autonomic dysreflexia history, bladder and bowel routines, skin status, equipment and medications.
• Stability requirement: no active infection, unhealed pressure injury, uncontrolled autonomic dysreflexia or recent surgery.
• Pre-treatment testing: complete blood count, metabolic panel, urinalysis and tumor markers.
• Quality-controlled cells: donor screening, infectious disease testing, and laboratory quality testing before release.
• SCI-adapted nursing: repositioning schedules, catheterization, bowel programs, safe transfers (including lift equipment when needed) and autonomic dysreflexia awareness.
• Accessible logistics: wheelchair-accessible transportation and rooms.
• Monitoring and observation, often for more than one night.

Long-term safety

Follow-up in SCI cell therapy studies typically extends from one to two years. Within these periods, serious long-term problems attributable to MSCs have not been reported. The nerve root clumping observed on MRI in the CELLTOP trial, without symptoms, is an example of why imaging and clinical follow-up continue after treatment. Keep regular appointments with your rehabilitation team and share your treatment records so any new findings can be interpreted in context.

Safety and benefit are separate questions

Being safe does not guarantee improvement. Early results are encouraging, with variation between patients. The U.S. National Institute of Neurological Disorders and Stroke (NINDS) and the World Health Organization emphasize rehabilitation, prevention of complications and long-term health management as the foundation of SCI care; regenerative therapy, if chosen, should support that work.

Regulatory context

The FDA has not approved stem cell products for SCI. In Japan, an autologous bone-marrow MSC product received conditional, time-limited approval in 2018. In Mexico, establishments that handle stem cells operate under sanitary licenses from COFEPRIS.

Who may be a safe candidate

• Medically stable, with no active infection or unhealed pressure injury.
• Autonomic dysreflexia, if present, recognized and manageable.
• Bladder, bowel and skin care routines that can be maintained during the stay.
• No cancer within the past five years.
• A caregiver available when needed, and access to rehabilitation afterward.

Preparing for treatment

Send recent MRI reports, your AIS classification, rehabilitation notes and a complete medication list. Describe your catheterization schedule, bowel program, transfer method, equipment needs and autonomic dysreflexia signs and treatment. Bring your pressure-relieving cushion, catheter supplies and medications for the whole trip plus extra. Plan travel with frequent pressure relief and hydration.

Signs to report after treatment

Seek urgent care for symptoms of autonomic dysreflexia that do not resolve after removing the trigger (pounding headache, flushing, sweating, very high blood pressure), high or persistent fever, signs of urinary infection, new redness or skin breakdown, leg swelling, shortness of breath or severe headache after a lumbar puncture.

Questions to ask during your evaluation

• Which route do you recommend, and what are its specific risks for me?
• How will autonomic dysreflexia be recognized and managed during my stay?
• How will my bladder, bowel and skin care be maintained?
• What transfer equipment and accessible transportation are available?
• What goals are realistic for my injury level?

Our team coordinates accessible transportation, room preparation and nursing support in advance, so your visit is planned around your specific needs.

Bottom line

MSC therapy for spinal cord injury has shown a favorable safety profile in early trials, with headache, pain and temporary fever among the most common effects. For people with SCI, safety depends heavily on preventing autonomic dysreflexia, pressure injuries, infections and blood clots through expert nursing and careful logistics. A medical evaluation can help determine whether this type of regenerative treatment is appropriate and safe for your injury, goals and medical history.