Nature Medicine: Breakthrough in stem cell + gene therapy for frostbite!

*For medical professionals only

Amyotrophic lateral sclerosis (ALS), commonly known as frostbite, is a spontaneous and fatal neurodegenerative disease

In the United States alone, about 5,000 new ALS are added each year[1].

Due to the death of motor neurons in the spinal cord and cerebral cortex, patients with ALS gradually atrophy their muscles and lose their ability to exercise, eventually causing vocal speech, swallowing disorders, and even respiratory failure, and patients are paralyzed or even die within 3 to 5 years of onset [1].

Currently, the U.

Recently, a research team led by Clive Svendsen from the Cedasennes Medical Center in the United States published the results of clinical trials of new therapies for ALS in the leading international medical journal Nature Medicine[1].

They developed a new ALS therapy that combines gene therapy and stem cell therapy to genetically engineer a neural progenitor cell line (CNS10) of human fetal cortex origin to express glial cell-derived neurotrophic factor (GDNF), thus solving the problem that

They conducted their first human clinical trial using this engineered neural progenitor cell (CNS10-NPC-GDNF), and through a 12-month clinical Phase 1/2a trial, as well as follow-up results from patients, they found that the new therapy was safe

Overall, this study provides a new therapy for ALS and demonstrates the safety

Screenshot of the first page of the article

Although ALS has been discovered for more than a century, there is still no clinical cure for ALS
.

About 10% of ALS cases are due to genetic mutations[4], and gene therapy is still developing [5,6].


In addition, cell therapies for ALS are constantly evolving, but one of the difficulties currently faced is that it is difficult for newly formed neurons in the body to form the correct connections
with muscles.

The results of an early Phase 2 clinical trial showed that the use of adult bone marrow-derived mesenchymal stem cells (MSCs) can briefly slow the course of the disease, possibly due to the mechanism by which MSCs can produce nutritional factors and anti-inflammatory factors [7].

Another Phase 2 clinical trial led by Brainstorm showed that MSCs were more effective[8], but subsequent large Phase 3 clinical trials (NCT03280056) failed
.

These clinical trials have at least demonstrated the safety of spinal cord transplantation in ALS patients, which is important
for the subsequent development of new cell therapies.

Astrocytes are cells that support neurons and may develop abnormalities in patients with ALS, thereby promoting the death of motor neurons [9
].

Healthy astrocytes have been shown to protect motor neurons[10], so restoring healthy astrocytes in patients with stem cell transplantation has the potential to alleviate damage to motor neurons in patients with ALS and thus slow down disease progression [11].

For decades, Clive Svendsen's research team has been working on cell therapies
for neurodegenerative diseases.

They transplanted human cortex-derived neural progenitor cells (hNPCs) into the central nervous system of rodents, pigs, and non-human primates, and these hNPCs survived and differentiated into astrocytes, protecting host cells against the development of aging and neurodegenerative diseases [12-16].

However, studies have shown that transplanting healthy hNPCs into ALS-mode rats does not slow down motor neuronal death and disease progression [13,16], suggesting that cell therapy may require additional nutritional support to achieve results
.

Gliocyte-derived neurotrophic factor GDNF is a nutritional growth factor that is very potent for both dopaminergic neurons and motor neurons, but it does not cross the blood-brain barrier [17,18], which makes subcutaneous or intrathecal administration less
effective for neurodegenerative diseases.

Therefore, the researchers want to combine cell therapy with GDNF delivery so that it can reach directly to the spinal cord and protect motor neurons
.

Previous findings by Clive Svendsen's team have demonstrated that hNPCs that can produce GDNF are transplanted into ALS-mode rats that can differentiate into astrocytes and safely deliver GDNF into the spinal cord to protect motor neurons [14,15].

To verify that this genetically engineered cell transplant therapy is safe for ALS patients, the researchers first conducted preclinical trials
.

Using neural progenitor cells of human fetal cortex origin, they genetically engineered stable GDNF expression and amplified and stored these cells under Good Manufacturing Practice (GMP) to obtain a product that can be used clinically, CNS10-NPC-GDNF
.

Trials in rats have shown that CNS10-NPC-GDNF can survive in the rat spinal cord, differentiate into astrocytes, protect motor neurons, and be safe
.

The injected cells can survive in the rat spinal cord

To inject CNS10-NPC-GDNF into the patient's spinal cord, they developed a novel injection device that can safely inject cells into the spinal cord of large animals
.

The results of preclinical trials conducted in rats and pigs showed that CNS10-NPC-GDNF transplantation could survive in the spinal cord, differentiate into astrocytes, produce GDNF, and also verified its safety
.

Subsequently, the researchers conducted the first human clinical trial
of CNS10-NPC-GDNF.

They recruited 18 patients with ALS for clinical studies and were randomly divided into two groups to transplant CNS10-NPC-GDNF
into the patient's unilateral lumbar spinal cord in a dose-increasing manner.

The first group of 9 patients received 10 injections from different sites on one side, each injecting 200,000 cells, for a total of 2 million cells
.

The second group was also 9 patients, 10 injections, 500,000 cells each time, for a total of 5 million cells
.

To avoid injury to motor neurons, these cells are not injected directly into the ventral horn of the spinal cord, but into the transitional area of the ventral and dorsal horns of the spinal cord, and the cells injected into this area can migrate to the ventral side to reach the location
of the motor neuron.

After the cell transplant, these patients were hospitalized for observation for 5 days, then examined at the 1st, 2nd, 3rd, 6th, 9th, and 12th months after transplantation, respectively, and followed up
for a long time.

Since CNS10-NPC-GDNF is an alloheterologous cell that may cause immune rejection, all participating patients received immunosuppressive therapy
.

In the short postoperative period, 89% of low-dose injection patients and 67% of high-dose injection patients reported paresthesia, discomfort or pain, and 9 patients reported pain for more than 6 months
.

In this clinical trial, most of the side effects experienced by patients were due to damage caused by ALS, immunosuppression or surgery, and no serious side effects were caused by transplanted cells
.

Therefore, this clinical trial proves the safety
of this treatment.

Imaging findings of patients involved in the treatment showed no abnormalities

The main purpose of this clinical trial is to demonstrate that injecting CNS10-NPC-GDNF into the spinal cord does not create safety issues and does not negatively affect
the patient's leg motor function.

As previous findings by Clive Svendsen's team have demonstrated, while disease progression varies greatly between patients with ALS, the rate of degeneration of muscle groups on both sides of each patient's body is very similar [19].

Therefore, they only injected a single spinal cord into the patient, so that the two legs of the same patient could be compared as a treatment group and a control group, so as to avoid errors between different patients affecting the test results
.

After the cell transplant treatment, they followed up the patients for a year, measuring leg muscle strength
in each patient in the treatment and control groups.

The results showed that the rate of decline in leg strength in the treatment group was slower than in the control group, and although there was no significant difference statistically, it at least showed that this treatment did not have a negative impact on
the patient's leg muscle strength.

Next, the researchers performed an autopsy of 13 participants who died as a result of disease progression and found that in the spinal cord of these patients, transplanted cells persisted and the production
of GDNF could be detected.

The transplanted cells in the spinal cord of the patient survived and GDNF levels were high

In addition, they counted the number of motor neurons in the spinal cord of these patients, and the results showed no significant difference
between the treatment group and the control group.

Overall, this clinical trial proves that this method of genetic engineering combined with stem cell therapy is safe, and with only one transplant, the transplanted cells can survive in the patient's body for a long time without serious negative impact on the patient, meeting the safety requirements, which is the key to further advancing clinical trials
.

In order to avoid injury to motor neurons at the ventral corner of the spinal cord, this study selected the transition area between the abdominal and dorsal corners of the spinal cord for injection, but the test results showed that most of the transplanted cells were still located in the dorsal corner of the spinal cord and less migrated into the ventral horn of the spinal cord, which may be a cause of chronic neuralgia in patients and the ineffective effect, in the next clinical trial, it may be necessary to choose a region closer to the abdominal angle for injection
.

In addition, although the clinical imaging scan results show that there are no abnormalities after the patient's cell transplantation, the autopsy results find that benign neuromas of 1-3 mm in size often appear at the injection site, which are composed of Schwann cells, which may be due to surgical damage and the nutritional factors secreted by the transplanted cells to promote the proliferation
of Schwann cells.

In this study, the effect of the therapy was not significant, which may be due to the inappropriate location of the cell transplant and the fact that the patient is already in a more advanced stage of the disease process, and further clinical trials in the future may need to consider injecting the transplanted cells closer to the abdominal corner of the spinal cord, as well as recruiting patients in the early stages of the disease for study
.

In addition, multisite therapy may enhance clinical efficacy, and the research team is already considering the use of this therapy for the cervical spinal cord and cerebral motor cortex of ALS patients
.

In fact, a Phase 1/2a clinical trial (NCT05306457) to deliver CNS10-NPC-GDNF to the motor cortex of ALS patients is already
underway.

In addition, the research team is also conducting a clinical trial to use CNS10-NPC in patients with pigmented retinitis (NCT04284293)[20], as well as for experimental new drug (IND) authorization studies
to use CNS10-NPC-GDNF in patients with Parkinson's disease.

It is expected that in the future, this therapy will benefit millions of patients with
ALS and other neurodegenerative diseases.

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