Using strands of microRNA molecules and a few carefully chosen genes, a team led by Dr. Sheng Ding at the Scripps Research Institute reprogrammed the genetic code of skin cells taken from a 55-year-old patient, transforming them into full-fledged neurons that actually synapse with each other.
As the lab’s report in the journal Cell Stem Cell1 explains, this new reprogramming method allows scientists to directly transform one cell type from an adult human into a normal, functional cell of a completely different type:
These human induced neurons (hiNs) exhibit typical neuronal morphology and marker gene expression, fire action potentials, and produce functional synapses between each other.
But this isn’t only a major breakthrough because the induced neurons work so well – it also represents a major leap forward in the field of cell transformation.
See, over the past few years, scientists have had some success at turning various kinds of human somatic (body) cells into artificial stem cells – known as induced pluripotent stem cells (iPSCs) - which can then be grown into various other types of cells.
This process is far from perfect – the successful conversion rate is has often been less than one percent, and it’s not yet clear whether iPSCs behave and grow exactly like their authentic stem cell equivalents. Still, iPSCs have proven to be useful tools for modeling diseases and testing drugs - and they may soon offer a less controversial alternative to research on human embryonic stem cells.
More recently, though, an even cooler technique has emerged: reprogramming one type of somatic cell directly into another type, without any intermediate iPSC stage. This is the technique Ding’s team used to make their induced neurons.
And that’s only the beginning, Ding says. For one thing, he thinks this method can be used to grow neurons for patients with Alzheimer’s and other neurodegenerative diseases – and they’ll be safe to transplant, because they’ll be grown from the patient’s own body:
Rather than using models made in yeast, flies or mice for disease research, all cell-reprogramming technology allows human brain, heart and other cells to be created from the skin cells of patients with a specific disease.
It’s also likely that as the technology improves, we’ll use it to grow transplantable tissue for hearts, lungs, and other organs – not to mention using it to study the development of various diseases in a specific patient’s body, in a controlled, safe environment:
“This will help us avoid any genome modifications,” said Dr. Ding. “These cells are not ready yet for transplantation, but this work removes some of the major technical hurdles to using reprogrammed cells to create transplant-ready cells for a host of diseases.”
As this research shows, we may soon be able to grow brand-new, guaranteed-compatible body parts from just a small sample of cells from the patient’s body. It looks like solutions to some age-old problems could be right on the horizon.
1. Clearly, Cell Press hired a whole team of marketing geniuses to come up with that name.