My day ends in a freezing microscope room in the basement of building 5 at 8:30 at night, starving for dinner, my attention riveted to the image before me as if it were finals week of American Idol.
I am one of the few people in the entire world that has been entrusted with the duty of tending human embryonic stem cells, which once formed the inner cell mass of a human embryo, capable of becoming an entire sentient being. A responsibility I do not take lightly. When my cells die for seemingly no reason or differentiate, as they are programmed to do into multiple cell types, I am staggered by the weight of my responsibility to maintain the sanctity of human life and the unique burden of proof I owe to the California tax payer who pay for my bread and shelter.
Everyday I come to work eager to solve a tiny problem that one day, like the power of raindrops to form rivers, may be combined with the discoveries of other researchers to potentially ameliorate the suffering of many thousands people. The goal of my research is to coax human embryonic stem cells, the tabula rasa of cells, to become specific types of peripheral neurons. I have tried to convince the cells that this is within their best interest, without success, for many months. My strategy has been to simply recapitulate the timing of human embryonic development in a plastic dish in the lab. A deceptively simple task that would rely on nature’s own course, instead of the existing chemical or animal reagent heavy protocols, previously applied by research teams in Israel and Germany. This is a necessary step if the cells I am attempting to make are ever to be used for human cell replacement therapies. They must be cheap, abundant and made in a way that minimizes the risk of disease transfer across species.
A typical day in the lab consists of me feeding and watering my garden of stem cells. Once a week I transplant them to a new pot so that they have room to grow. I am a steward, benefactor, husbandry expert and teacher. I take some of the most gifted students each week and put them into special education classes. That is to say, I take a subset of particularly good-looking cells and suspend them in specific media that allows them to become neural progenitors. After five to ten days the cells are semi-specialized. They are like HVAC technicians, specialists in regulating the temperature of your home but incapable of hooking up the cable or wiring the spare room for light. They can now form any type of the thousand or so odd components of the nervous system but they can no longer form the cells of the liver, lungs or pancreas, for instance. My next task will be to ask them to become so specialized that they can only do one thing well. Many research teams across the world do this exact same thing but this is where we part ways. I have etched out my corner of the scientific playpen with the least sexy-est of neural subtypes, avoiding the stomping grounds of the immensely popular central nervous system. The neurons I hope to make will not cure Parkinson’s or Alzheimer’s or repair a severed spinal cord, instead they may one day replace any nerves outside of the brain and spinal cord that have been damaged, such as the nerves that provide us with touch, taste, sight, smell and hearing as well as a few others.
Recently, I have grown my neural progenitors on a lawn of complex substrate, a naturally occurring component of the developing embryo that peripheral neurons have been known to take a special liking to in vivo. I have fertilized them with a rich, loamy mixture of cytokines and growth factors, sugars and antioxidants. In theory, I can detect proteins specific to the type of neurons I am searching for with antibodies labeled in brilliant fluorescent colors: crimson, emerald and cerulean. I am searching for a protein aptly named Peripherin, an integral component of these specific cells discovered in 1982 by Madeleine Portier, Frangois Gros and colleagues, in the cells that I have grown under the new circumstances for two weeks. I start the two days long protocol with trepidation. Will my cells have accepted my guidance and graduated to become the mature neurons of the peripheral nervous system? If they have not been persuaded I will go back to the literature, searching for clues that have been provided by others studying the developing nervous systems of frogs, chickens and mice.
I finish the staining protocol, lovingly attach a coverslip to the glass slide, preserving the rare fluorescence I hope to observe and make the quick walk to the microscope room. Before I leave the lab I grab a hoodie and trade my flip-flops for socks and sneakers. I know from experience that the microscope room must be kept on the cool side to counteract the heat given off by the many mechanical calisthenics of those complex instruments.
I center my slide above the objective and fiddle with the focus knobs until the gray and white ghosts before me sharpen into the shape of cells. I hold my breath as I switch from the white light to the UV light that will excite any fluorescent molecules that have stuck to my cells. Fine crimson filigrees of neural process extend before my eyes and I feel as elated and nervous as a new bride gazing through a veil of lace. Finally! My cells have willing done what was asked of them and I frantically snap the pictures that will be the proof of their existence. Dinner will wait.