A team of Stanford University researchers have managed to take elements of the heart and turn them into elements of the head. The medical researchers from Stanford's School of Medicine converted human blood cells directly into working brain cells.
They transformed an immune-system cell into a completely different cell with a different shape and different function. The team hopes to one day use that technique to study a patient's brain through a simple blood sample.
“Blood is one of the easiest biological samples to obtain,” said Marius Wernig, MD, associate professor of pathology and a member of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine. “Nearly every patient who walks into a hospital leaves a blood sample, and often these samples are frozen and stored for future study. This technique is a breakthrough that opens the possibility to learn about complex disease processes by studying large numbers of patients.”
The transformation happened through a process called transdifferentiation. It can generate over 50,000 neurons from a single milliliter of blood, and it takes roughly three weeks for the process to occur. This transdifferentiation can take place with either fresh or frozen/stored blood samples.
Wernig developed transdifferentiation in 2010 while showing his colleagues how to convert a mouse's skin cells into neurons. In those early research stages, Wernig induced the cells to become pluripotent, which is a stage where cells can become nearly any other type of tissue. Wernig wanted to show how that process could be applied to humans.
However, there were some problems in creating pluripotent cells.
“Generating induced pluripotent stem cells from large numbers of patients is expensive and laborious. Moreover, obtaining skin cells involves an invasive and painful procedure,” Wernig said. “The prospect of generating iPS cells from hundreds of patients is daunting and would require automation of the complex reprogramming process.”
The researchers noted that it's technically feasible to convert skin cells to neurons directly. However, it requires biopsied skin cells to be grown in a lab first. The time-intensive process increases the possibility for genetic mutations not found in the cell's original human. The team needed a more efficient way to make those neurons.
Wernig shifted his focus to T cells -- immune cells found in the blood. T cells protect the human body by killing off infected or potentially cancerous cells. They are, in essence, the complete opposite of a neuron. Neurons are much more slender and capable of conducting electrical impulses between cells. But despite an extensive list of differences, Wernig and the team managed to transform the cells with ease much to their surprise.
“It’s kind of shocking how simple it is to convert T cells into functional neurons in just a few days,” Wernig said. “T cells are very specialized immune cells with a simple round shape, so the rapid transformation is somewhat mind-boggling.”
“We now have a way to directly study the neuronal function of, in principle, hundreds of people with schizophrenia and autism.”
The neurons created through the process aren't exactly like human neurons we are born with. These neurons don't have the ability to form synapses between them. However, they can successfully carry out the basic functions of a neuron, according to the team. That's enough for the team to potentially develop the process further in order to better understand issues like schizophrenia and autistic tendencies.
“We now have a way to directly study the neuronal function of, in principle, hundreds of people with schizophrenia and autism,” Wernig said. “For decades we’ve had very few clues about the origins of these disorders or how to treat them. Now we can start to answer so many questions.”