A research team at the University of Southern California (USC) will be initiating a Phase 1 clinical trial to test the effectiveness of their compound “Allo,” which promotes brain cell regeneration, in Alzheimer’s patients.
This new trial is one of four that are investigating new therapeutic targets in Alzheimer’s disease. These trials will also incorporate novel approaches to participant identification and selection.
These trials were reported at the Alzheimer’s Association International Conference in Boston. According to Roberta Brinton of USC, again and Alzheimer’s disease (AD) are characterized by a decline in the ability of the body to self-renew and repair (and this includes the brain). However, the capacity for regeneration is retained, albeit at a decreased level.
Allopregnanolone (3α-hydroxy-5α-pregnan-20-one), or Allo for short, is a neurosteroid that naturally occurs in the brain. Small quantities of it can also be found in the bloodstream. Previous studies have shown that Allo can improve cognitive function in older laboratory animals and in animal models of AD (see Chen S, Wang JM, Irwin RW, Yao J, Liu L, et al. (2011) Allopregnanolone Promotes Regeneration and Reduces β-Amyloid Burden in a Preclinical Model of Alzheimer’s Disease. PLoS ONE 6(8): e2429).
Robert Diaz Brinton, Professor of Pharmacology and Pharmaceutical Sciences, Biomedical Engineering and Neurology at USC, reported the design of her clinical study at the Alzheimer’s Association International Conference. In this trial, participants diagnosed with mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s disease will receive doses of Allo, administered once-per-week to establish a safe dose that is well tolerated.
Since Allo is already naturally synthesized in the brain, and reaches high levels during the third trimester of pregnancy, Brinton and her colleagues were able to circumvent the first few stages of safety testing. The secondary goals of this clinical trial include assessing potential short-term effects of Allo dosing on cognition and MRI indicators of AD. Such data will inform a Phase 2 proof of concept trial with MRI-based biomarkers of regeneration efficacy.
“Allopregnanolone is a well-characterized agent with a very promising track record of promoting neural stem cells generation and restoring cognitive function in animal models of Alzheimer’s,” said Brinton. “We consider Allopregnanolone a first class regenerative therapeutic for mild cognitive impairment and Alzheimer’s. Our hope is that, through further research, we will add Allo to the roster of Alzheimer’s treatments.”
One of the critical issues to consider in clinical trials such as this is the ongoing and relentlessly progressive burden of brain death caused AD. It is not sufficient to only generate new neurons and promote the survival of those neurons. It is also necessary to reduce the ongoing burden of the pathology of AD in order for treatments to accrue long-term benefits.
Brinton commented that “we were very encouraged to discover that Allo reduced the burden of Alzheimer’s pathology. Out findings are very exciting as they show that Allo increases the energy capacity of the brain. This is important because the generation of new neurons, new synaptic circuits and synaptic transmission all require substantial energy.”
Disclaimer: I am reporting on this experiment because of its significance for people with spinal cord-injuries even though I remain appalled at the manner in which the stem cells were acquired.
An international research team has reported that a single set of injections of human neural stem cells had provided significant neuronal regeneration and improvement of function in rats impaired by acute spinal cord injury.
Dr. Martin Marsala, who is professor of anesthesiology at the University of California, San Diego, with colleagues from academic institutions in Slovakia, the Czech Republic, and the Netherlands, used neural stem cells derived from an aborted human fetus to treat spinal cord-injured rats.
Sprague-Dawley rats received spinal cord injuries at the level of the third lumbar vertebra by means of compression. Such injuries render the rats incapable of using their hind legs. They cannot climb a ladder, walk a catwalk or perform other tasks that require the effective use of their hind legs.
The stem cells that were transplanted into the spinal cords of these rats were NSI-566RSC cells, which were provided by the biotechnology company Neuralstem. These cells were initially isolated from the spinal cord of an eight-week old human fetus whose life was terminated through elective abortion. These cells have been grown in culture and split many times. They are a neural stem cell culture that has the capacity to form neurons and glia.
The rats were broken into six groups, and four of these groups received spinal cord injuries. One of these spinal cord-injured groups received injections of were injured NSI-566RSC cells (12 injections total, about 20,000 cells per microliter of fluid injected), another received injections of only fluid, and the third group received no injections. The final spinal cord-injured group of rats received injections of NSI-566RSC cells that had been genetically engineered to express a green glowing protein. Another group of rats were operated on, but no spinal cord injury was given to these animals, and the final group of rats were never operated on.
All rats that received injections of cells were administered powerful drugs to prevent their immune systems from rejecting the administered human cells before the injections (methylprednisolone acetate for those who are interested at 10 mg / kg), and after the stem cell injections (tacrolimus at 1.5 mg / kg).
The results were significant and exciting. In the words of Marsala, “The primary benefits were improvement in the positioning and control of paws during walking tests and suppression of muscle spasticity.” Spasticity refers to an exaggerated muscle tone or uncontrolled spasms of muscles. Spasticity is a serious and common complication of traumatic injury. It can cause severe cramping and uncontrolled contractions of muscles, which increases the patient’s pain and decreases their control.
First, it is clear from several control experiments that the injection procedure did not affect the spinal cord function of these animals, since the sham injected rats had perfectly normal use of their hind limbs and normal sensory function of their limbs. Thus the injection procedure is innocuous. Also, the use of the drugs to suppress the immune response were also equally unimportant when it came to the spinal cord health of the rats.
Two months after the stem cell injections, the rats were subjected to the “catwalk test,” in which the animals walked a narrow path and their paw position was assessed. As you can see in the figure below, the stem cell-injected rats have a paw position that is far more similar to the normal rats than to the spinal cord injured rats.
Secondly, when muscle spasticity was measured, the stem cell-injected rats showed definite decreases in muscle spasticity. The spinal cord-injured rats that received no stem cell injections showed no such changes.
Sensory assessments also showed improvements in the stem cell-treated rats, but the improvements were not stellar. Nevertheless, the stem cell-treated rats progressively improved in their sensory sensitivity whereas the non-treated spinal cord-injured rats consistently showed no such improvement.
What were the implanted cells doing? To answer this question, Marsala and his co-workers examined tissue sections of spinal cords from the rats implanted with the glowing green stem cells. According to Marsala, the implanted neural stem cells are stimulating host neuron regeneration and partially replacing the function of lost neurons.
Marsala explained: “Grafted spinal stem cells are a rich source of different growth factors which can have a neuroprotective effect and can promote sprouting of nerve fibers of host neurons. We have demonstrated that grafted neurons can develop contacts with the host neurons and, to some extent, restore the connectivity between centers, above and below the injury, which are involved in motor and sensory processing.”
The implanted neural stem cells definitely showed extensive integration with the spinal nerves of the host rats. Again Marsala, “In all cell-grafted animals, there was a robust engraftment and neuronal maturation of grafted human neurons was noted.” Marsala continued: “Importantly cysts or cavities were not present in any cell-treated animal. The injury-caused cavity was completely filled by grafted cells.”
Marsala’s goal is to used a neuronal stem cell line derived from a patient-specific induced pluripotent stem cell line in a clinical trial. For now, the UC San Diego Institutional Review Board or IRB is reviewing a small phase 1 clinical trial to test the safety and efficacy of this neural stem cell line in patients with spinal cord injuries who have no feeling or motor function below the level of the spinal cord injury.