Retinal transplants and welcomes

September 4, 2012 § 1 Comment

To all professors, students, and online passers-by:

You are now reading the first in a semester-long series of blog posts chronicling my descent into the academic lair that is science fiction. Sitting at the interface between two areas of human knowledge seemingly distant and incapable of crosstalk as science and literature, science fiction exhibits a hybrid nature – serving as fodder for viable literary discussion while informing audiences of the ramifications of modern scientific developments. Indeed, science fiction writers face two stringent and somewhat conflicting standards when set to their creative devices: how am I to write literature interesting to engage readers, yet scientifically plausible to escape the realm of mere speculation and fantasy to earn the title of ‘science fiction’?

I won’t be writing any sci-fi stories until later in the semester. Rather, at present I am charged with the task of devising a topic for a science fiction story based upon projected breakthroughs in any scientific discipline. I will take cues from my own research at Vanderbilt University Medical Center in the ophthalmology unit – more specifically, my project concerning the molecular mechanisms of neuronal degeneration in glaucomatous retinas. The topic I want to see as the premise of a good sci-fi story is whole retinal transplants in humans.

Any neuroscience student will tell you that degenerative diseases of the retina are non-reversible: that is, no cure exists that replenishes the mosaics of precious light-sensing cells at the back of your eye as they die out. As aging is the primary risk factor for such diseases, our only recourse at present is early detection to delay the onset of vision loss. But what if we can evade painstaking diagnoses and treatment by simply ‘giving’ you a new retina – one that is grown in vitro? Such hypothetical treatment would make our lives much easier, but several obstacles stand between us and the prospect of retinas as replaceable as your grandma’s dentures.

The first is that the retina comprises delicately alternating meshworks of neurons as well as empty spaces where neurons interface (the proper jargon is ‘synapse’) with one another. Transplanting mosaics of alternating cells and extracellular empty space presents the clear danger of cellular collapse – the squashing together of various neuronal layers that will lead to retinal inviability.  Second, different types of neurons must occupy certain layers of the retina ‘mosaic’ in order for signaling transduction pathways to work properly. The assurance of cell specificity at the microscopic level of in vitro growth is a daunting task. Until these two obstacles can be surmounted, retinal transplants are ripe for science fiction stories.

But why bother writing about retinal replacements? As essential as vision may be, why should I worry so early in my life about a disease that doesn’t even bear a pathological (germ-bearing) component? The key in many compelling sci-fi stories, especially ones written in the field of biomedical science, is that of unanticipated and perhaps adverse consequences of proposed cures. Indeed, plenty can go wrong (and will go wrong during initial human testing) when one consents to having his or her retina replaced by one grown in vitro.

The first and most obvious risk regarding transplants of foreign tissue is rejection; perhaps pre-existing retinal cells in the back of our eyes find the transplanted retina to be serologically incompatible. Blindness and/or onset of other ocular problems will ensue, easily affecting thousands of patients who may consent to such treatment. Homo sapiens sapiens encountering mass blindness certainly makes for an interesting sci-fi premise; with many of us suddenly forced to put up without arguably our most precious sense, how will we evolve to rise to the occasion? In what ways will the world as well as technology change to accommodate our unexpected freedom from sight? But on the flip side, preparation of ex vivo tissue involves tinkering with the molecular composition of cells to ensure their survival outside the human body. This very manipulation with the chemical balance of neuronal tissue might enable our retinal neurons to fire more rapidly, giving us super-vision and the lightning-fast reflexes of a hawk. How will those of us with this new apparent superpower keep pace with the rest of society? Moreover, will drastically improved vision serve as the catalyst for other mutations enabling us to essentially morph into demigods?

Grounded in hard biomedical research and fact, retinal transplants are a goal to which many research teams around the world work towards nowadays. To successfully prepare human retinas ex vivo for diseased patients would definitely serve as the crowning achievement for any ophthalmological investigator. But until then, the idea remains firmly rooted in domain of science fiction.
Sean Justin Lee


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§ One Response to Retinal transplants and welcomes

  • mightymongoose says:

    I enjoyed reading about your research, especially since I hardly know anything about retinal transplants. Regarding the limitations of in vitro and ex vivo culture, have you read any omentum studies? I was doing research on adult stem cell to beta cell differentiation in the pancreas over the summer, and one of my advisers showed me some omentum research. Scientists took this membrane, wrapped it around bits of damaged pancreas, and saw the emergence of new, insulin-producing cells triggered by the omentum’s stem cell growth factors. I was curious if the same response might be seen in retina damage models.


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