The breakthrough could lead to better pain medication.
McMaster's Stem Cell and Cancer Research Institute (SCC-RI)
Taking a trip to a clinic to give blood has just become a mission with a dual purpose. Scientists at McMaster University have discovered how to take those blood samples and make adult sensory neurons.
Neurons are cells of the neurological system that can be broadly divided into both central nervous system (think brain and spinal cord) and peripheral nervous system. The peripheral cells communicate with the spinal cord and brain from the outfield, and relay things like temperature and pressure and most importantly, pain detection, all the way to a person's fingertips.
The breakthrough, published today in the journal Cell Reports, was the result of roughly five years of research by lead researcher Dr. Mick Bhatia, director of the McMaster Stem Cell and Cancer Research Institute, and his team of 12 scientists. On day one, they posed this challenge: What if we could make neural cells from blood?
"I think we are most excited about the fact that we are not only able to make central nervous system cells, but we are able to make peripheral nervous system cells," said Bhatia.
A division between the two systems is important when identifying new drugs that will activate the peripheral nervous system, but have no effect on the central nervous system. Researchers have been able to treat patients of acute diseases like HIV, heart disease, and cancer, who previously had a very short life span. But the problem now is one of quality of life, because the survivors are suffering a lot due to chronic pain.
This paves the way for a discovery of new pain drugs that don't just numb the perception of pain
"The medications we use for pain have gone unchanged for decades," Bhatia explained to me over the phone. "They are limited to things like narcotics and opiates." These drugs are not only addictive, but they also cause the patient to experience extreme drowsiness because these drugs are entering the central nervous system.
After years of trial and error, the researchers have narrowed down the conversion process to 30 days. First, they must put the blood cells into in vitro petri dishes. They then have to keep the cells in an area that is conducive for the growth and survival of neural cell types.
Once they had the technology down, they then need to spend time trying to reproduce it in other people's hands. "That reproducibility is critical for us because it is something that is starting to be a big question in the field right now," explains Bhatia. A question that haunts stem cell researchers, and really researchers everywhere is: When you hand the technology off to someone else, can they get it to work?
Bhatia compares the process to two people using identical ingredients to bake a batch of chocolate chip cookies. When those two people reconvene the next day, he says those cookies will likely look and taste completely different. In his case, they have a process that is really complex and based on individual samples of blood.
"I think we shouldn't trivialize that people will have difficulty reproducing it identically," he says, which is why they spent a year having others test the technology. "We want to make our recipe as good as chocolate chip cookies."
The researchers are now beginning to combine their technology with drug screening by taking some known compounds (purified chemical structures) and adding them to micro dishes of central nervous system neurons versus peripheral system neurons. They are hoping to see an effect on the peripheral, but no effect on the central. Those drugs would be then be the preferred candidates for study.
This paves the way for a discovery of new pain drugs that don't just numb the perception of pain. "We really don't know why you might feel pain from an injury differently than I would," Bhatia says. In patients with type 2 diabetes for example, there is a constant feeling of numbness and weakness. But what is not understood is why some people have severe diabetes and are unable to regulate glucose, but they experience no numbness, while other experience severe cases of it.
"What this technology allows us to do is not only convert the blood cells to neural cells, which is a technical convenience to do things like drug discovery, but it also captures the DNA of that individual," explained Bhatia.
This hasn't been able to be done at a systemic level yet because patients with neuropathy are grouped as if they are all the same. The reality is they are not. The term "personalized medicine" is an emerging practice that uses an individual's genetic profile to guide decisions made in regard to the prevention, diagnosis, and treatment of a disease. This what Bhatia hopes this technology will be used for in the future.