|Posted by Mark Cantrell on June 20, 2017 at 7:25 PM|
The cells that Man made
We many not be able to grow custom-made humans in vats just yet, writes Mark Cantrell, but scientists have cracked a clunky problem – how to 'bulk grow' brain and muscle tissues from stem cells in just a matter of days
SCIENTISTS at the University of Cambridge have figured out how to manufacture millions of human brain and muscle cells in a matter of days, but growing a custom-made anthropoid in a vat remains a distant prospect.
For that we probably ought to be grateful, but it's not as if the research team is looking to emulate some 21st Century Hollywood Frankenstein. Far from it. This is about understanding human biology and therapeutic science a whole lot better, and – maybe someday – creating 'spare parts' at the cellular level to restore damaged tissue in we natural-born hominids.
When you think that a human infant grows from a single cell – a fertilised egg – in the mother's womb, it takes nine months to grow the plethora of different cell types that make up the resulting organism. Not just nerve and muscle cells, but skin, liver, bone, kidney, white and red blood cells; an entire menagerie of specialised cell types. All of them are made from just one ‘master’ – stem cells.
In a human, it takes nine to 12 months for a single brain cell to develop fully. Using current techniques, it can take between three and 20 weeks to create human brain cells, including grey matter (neurons) and white matter (the supporting oligodendrocytes, which build the insulating sheath around the axons and aid signal transmission) from an induced pluripotent stem cell.
These are stem cells generated by reprogramming a skin cell to its 'master' stage. However, these methods are complex and time consuming – turning back time is difficult – and the process usually produces a mixed population of cells.
Now a research team from the University of Cambridge and the Wellcome Trust Sanger Institute has created a new technique that allows millions of human brain and muscle cells to be generated in just a matter of days.
“What is really exciting is we only needed to change a few ingredients – transcription factors – to produce the exact cells we wanted in less than a week. We over-expressed factors that make stem cells directly convert into the desired cells, thereby bypassing development and shortening the process to just a few days,” said study author Professor Ludovic Vallier, from the Wellcome Trust Medical Research Centre Stem Cell Institute at the University of Cambridge.
Human pluripotent stem cells are the 'master cells'. By switching on different parts of the DNA in the nucleus and suppressing others, they are able to develop into almost any type of tissue, including brain cells. As a result, they are considered to have huge potential for studying human development and the impact of diseases, including cancer, Alzheimer's disease, multiple sclerosis, and heart disease.
Dr Mark Kotter, lead author and clinician, from the University of Cambridge, said: “Neurons produced in this study are already being used to understand brain development and function. This method opens the doors to producing all sorts of hard-to-access cells and tissues so we can better our understanding of diseases and the response of these tissues to newly developed therapies.”
The technique they devised for speeding up the process uses a new platform technology called OPTi-OX, which optimises the way of switching on genes in human stem cells. Scientists applied OPTi-OX to the production of millions of nearly identical cells in a matter of days. There's also rather more to the technique than 'brain and brawn' too; OPTI-OX is said to hold the possibility of generating any cell type at “unprecedented purities” in the same short timeframe.
To create the neurons, oligodendrocytes, and muscle cells, the researchers altered DNA in the stem cells. By switching on carefully selected genes, they reprogrammed the stem cells to create a large and nearly pure population of identical cells. The team say that the ability to produce as many cells as desired combined with the speed of development gives an advantage over other methods. Namely, the new method offers the scope to discover new drugs and potentially therapeutic applications in which large amounts of cells are needed.
What's more, OPTi-OX also has the possibility to generate new cell types that may be uncovered by the Human Cell Atlas.
“When we receive a wealth of information on the discovery of new cells from large scale projects, like the Human Cell Atlas, it means we'll be able to apply this method to produce any type of cell in the body – but in a dish.”