Israeli radiation disease treatment passes major hurdle

The NIH is relying on Pluristem’s placenta-based stem cell treatment as a worst-case insurance policy

Pluristem workers process placenta for the company's cell-based therapy products (Courtesy)
Pluristem workers process placenta for the company's cell-based therapy products (Courtesy)

As the West negotiates with Iran over its nuclear program, the United States National Institutes of Health has been testing an Israeli treatment that offers protection from the ravages of radiation sickness, which occurs after exposure to high levels of radiation.

With the successful conclusion of the latest of a series of tests, Pluristem‘s placenta-based PLX-R18 stem cells to treat bone marrow damaged by exposure to high levels of radiation took a giant step toward FDA approval and government procurement. Currently, Pluristem has the only viable treatment to stop the spread of radiation sickness.

“Our PLX-R18 cell product was developed and targeted to become a strong candidate for government procurement programs designed to protect the population in the case of exposure to dangerous levels of radiation,” said Zami Aberman, chairman and CEO of Pluristem. “PLX-R18 cells are an off-the-shelf cell therapy product with a long shelf life. They do not require matching before use and can be administered through intramuscular injection. These features are important to facilitate rapid initiation of treatment on a large scale.”

Acute radiation syndrome is a condition caused by high-dose irradiation that can involve severe, sometimes lethal, damage to the bone marrow as well as other physiologic systems and organs. The wide variety of health effects in ARS occur within several days to months after exposure to high doses of ionizing radiation from a nuclear event, such as a nuclear power plant accident. Especially affected is bone marrow, with problems leading to severe anemia, hemorrhages and failure of the immune system.

The NIH tests showed that injection of PLX-R18 cells into muscle, as compared to a placebo, resulted in a “statistically significant improvement in the recovery of white blood cell, red blood cell, and platelet levels in animals exposed to high levels of radiation” – the three blood lineages that the body is unable to produce due to acute radiation syndrome, Pluristem said.

“The data also suggested that the treatment may potentially be able to shorten time to recovery,” the company added.

While there are many companies today harvesting human cells – like stem cells – to develop therapeutic products, Pluristem was the first, and is still one of the only, companies harvesting them from placenta.

Placenta, according to researchers, enhances cell repair and speeds up the healing process significantly. Using human placenta – because it is more compatible with the human genome – Pluristem processes and enhances the cells, using proprietary methods inside a bioreactor created by the company. The result, said Aberman, is “a drug delivery platform that releases a cocktail of therapeutic proteins in response to a host of local and systemic inflammatory and ischemic diseases.”

According to Pluristem researchers, the placenta contains mesenchymal-like adherent stromal cells, which have been found by researchers to have significant therapeutic potential. The cells promote tissue repair, possibly by secreting biologically active substances, including cytokines, that modulate immune response, along with factors that enhance the growth of blood vessels. These cells stimulate the body’s own mechanisms to heal damaged tissues.

And because placental cells themselves are immunoprivileged (meaning that they do not elicit an immunological response from the body, as other cells do), they can be used freely for any purpose, without requiring tissue matching.

Pluristem “harvests” the placenta from a hospital in northern Israel, where it is donated by women undergoing caesarean section births. The births are planned in advance, allowing the company to set up the equipment needed to ensure that the placenta is still living and not contaminated by the environment. It is then rushed to Pluristem’s facility, where it is then processed into PLX (PLacental eXpanded) cells, for use in a variety of applications.

The results of the current study indicated that injecting mice with PLX-R18 cells has a healing effect on bone marrow. According to Pluristem researchers, the cells secrete therapeutic proteins which are transferred into the bones, positively affecting marrow, although the cells themselves remain in the muscle into which they were initially injected.

While additional animal trials are needed prior to US Food and Drug Administration (FDA) approval of PLX-R18 for use in ARS, no human trials would be required because product development is conducted under the FDA’s Animal Rule, which comes into play when human trials are impractical or too dangerous.

While the NIH sees Pluristem’s technology as a sort of “insurance policy” to deal with a worst-case scenario, the company sees many other uses for its cells. Currently, Pluristem is developing PLX-R18 cells for other potential uses, such as the treatment of bone marrow deficiency. Trials for this indication are ongoing at Case Western University and Hadassah Medical Center in Israel.

“We’ve just completed a two-year development cycle for our PLX-RAD cells, and have also developed new manufacturing equipment, methods and know-how. We believe that our state-of-the-art technology platform can be used to create additional cell products from the placenta, tailored to potentially deliver targeted treatments for a variety of new indications,” said Aberman.

“Our technology platform, robust manufacturing capabilities and broad IP portfolio open the door for potential institutional and commercial partners, and we’re pleased with the level of interest we have received in our technology platform. Pluristem is in a unique position to be a leader in the cell therapy industry.”

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