Amanda Zimmerman, Senior Scientist at the Christopher and Dana Reeve Foundation, has written an interesting analysis of a 2017 study published in Nature, which reported the results of delivering stem cells with a modified form of tissue-type plasminogen activator (tPA) — a drug commonly used to treat non-hemorrhagic stroke — to rats.
The study was conducted by Yasuhiro Shiga from the Department of Anesthesiology, University of California, San Diego; Akina Shiga from the Department of Orthopaedic Surgery and Graduate School of Medicine, Chiba University, Japan, and other researchers from the University of California, USA.
This article published on scienceblog.com summaries the findings of the study.
In a laboratory dish, the researchers had added the modified tPA to neural progenitor cells — the precursors to neurons. They had generated these pre-neurons from induced pluripotent stem cells, a special kind of stem cell that can be derived from a person’s skin cells. After 15 minutes, the researchers transferred either tPA-conditioned or unconditioned neural progenitor cells to the injury site in a rat model of severe spinal cord injury, the article explains.
Two months after treatment, the researchers found 2.5-fold more tPA-conditioned neural progenitor cells than unconditioned cells still present in the rats. What’s more, the tPA-conditioned cells had begun specialising into full-fledged neurons, with axons (branches) emerging from the site of transplantation and extending as far as four vertebrae away. According to the researchers, that was unusual, the article says.
Even more surprisingly, in rats with modified tPA it was observed that there was a three-fold increase in motor activity after four months, as measured using a well-established scoring system that quantifies a combination of rat joint and limb movements, trunk stability, paw and tail positioning, stepping and coordination, the article added.
Zimmerman commented: “It’s still unknown whether this sort of strategy will have success in chronic SCI, or whether pre-treatment of subject-derived hiNPCs is a viable method for humans”.
“Yet, I wanted to highlight this study as one of the stem cell animal studies that seek to answer the appropriate questions:
“(1) what is the best type and condition of stem cell to implant,
“(2) can we do anything to improve the chance of success for the stem cells to appropriately implant, survive, and grow;
“(3) does treatment result in meaningful, functional improvement,
“(4) what do the stem cells become (non-neural cells, spinal cord neurons, motor neurons) as time progresses post implantation, and
“(5) are there any obvious detrimental side effects after implantation? To fully answer (5), researchers might need to assess many other functions, including chronic pain and autonomic function, over a longer time window, but this is a good start”, added Zimmerman.
“I’m looking forward to seeing where this group goes next,” she concluded.
You can read Zimmerman’s full article here: https://www.christopherreeve.org/blog/research-news/stem-cell-therapies-making-a-comeback