Cytocentric Visionaries: Jan Jensen, Trailhead BioSystems
Part Two: Controlling Stray Cell Fates in Culture
In Part One, we discussed Trailhead’s unbiased system of cell signaling optimization for differentiation. Here we continue our conversation with Dr. Jan Jensen, CSO of Trailhead BioSystems in Cleveland, OH. Today we talk about cell fate and reprogramming. Read the full interview to learn about the impact of cell reprogramming in clinical applications.
AH: You are working on a pancreatic beta cell project right now?
JJ: That’s one of the projects. We are actually investigating protocol development for a lot of different customers. The motto of Trailhead Biosystems is that ‘No cell is out of reach.’ Based on the data that we have obtained, we are not afraid of going into any lineage represented by human cells. That’s the differentiating ability of Trailhead Biosystems.
We are building a beta cell protocol as part of my work at the Cleveland Clinic. Instead of starting with the literature and just working off that knowledge base where we were, we decided to go back to the very ground state of pluripotency and build our protocol up from scratch.
That has actually worked pretty well. We have succeeded in building a new pancreatic beta cell protocol that differentiates itself substantially from leading literature and is a little further than halfway down in the differentiation protocol. We are working on optimizing glucose responsiveness and beta cell maturity of the cells.
That was only possible because we followed the data in an unbiased way.
AH: Why use ground-state embryonic cells to start with rather than reprogramming or trans-differentiating another mature cell type?
JJ: I’ll probably insult a lot of people when I say that my personal view on reprogramming is that it’s quite like cheating. Through the work of Shinya Yamanaka and his colleagues we have a tremendous technology available to us in the induced pluripotent state reprogramming, and so that, in and of its own, should be the evidence to prove me wrong!
The ground state of pluripotency that rests on the Yamanaka cocktail is a self-perpetuating one under certain conditions. Because that state is expressing telomerase and is an immortal state, iPS cells can expand without compromising the competency for going into the separate lineages.
It is simply a remarkable ability we now have to revert mature cells from any person into a state from which we can generate new specialized, and in some cases ask important questions about a possible disease of the person from which we derived the cells. It is truly a well deserved Nobel Prize that was awarded for this observation.
But I have more reservations about reprogramming from one specialized state directly into the other.
In this situation, we’re looking towards transcription factor complements that can take a state from type A to type B. It may work, but we’re always worried; how much of the original state A is left in state B? Did we completely reprogram? Secondly, if state B has a poor intrinsic stability then we’re unlikely to rest in it, and the phenotype will not remain stable, contrary to what we know happens , during IPS reprogramming.
So that’s why I think it’s cheating. Nature has absolutely no way, unless you for instance are a drosophila embryo that has not completely cellularized early, to put transcription factor combinations in certain locations. Nature is not doing this.
If we do it for clinical use, we may be fortunate, but it may also be that the product we get out in the end is inferior.
AH: So you are more confident of the exact differentiation state cells in your protocols?
JJ: We’ve developed recipes that display far higher robustness, often converting in excess of 99% of the cells in an entire culture rapidly into a new state.
One of the biggest problems when we see protocols in literature is that they are rarely able to convince us that there is a robust change from a given state to the other. That is why we’re so pestered with problems with stray fates.
Cells, when they’re multipotent or pluripotent, can go in many different directions. If we don’t restrict their fates through locking in pathways they will take these fate opportunities in culture.
Then we’re going to compound a problem of having stray fates in our cultures as we go along in multistage protocols, eventually not being able to reach the level of purity that we need for clinical trials.
If we can’t achieve homogeneity of cells and we have to go into patients with a mix of cells, for which we don’t know what many of them are or what they do, it’s more than likely that the clinical outcomes will begin to suffer.
That’s one of the major problems that we have in clinical trials right now, is that we have to use what we have, which is poorly differentiated cells.
These clinical trials are, for the most part, not yielding as impressive results as we would like to see. Our take on this is that we can help to build protocols that have more control in the differentiation arena than those that are currently and typically seen in papers.
You can lock in more than a limited number of pathways, like 2 or 3. When you are up to 6, 8, 10, maybe even more pathways, then the cells get very little freedom to wobble in the differentiation state and that is why we get better conversion robustness in the designs.
In Part Three, we continue our discussion with Dr. Jensen, talking about the importance of full-time oxygen control and full-time protection of robotics for defining optimal differentiation signal combinations.
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About the Author
Alicia D Henn, PhD, MBA
Alicia Henn has been the Chief Scientific Officer of BioSpherix, Ltd for two years. Previously, she was a researcher at the Center for Biodefense Immune Modeling in Rochester, NY. Alicia obtained her PhD in molecular pharmacology and cancer therapeutics from Roswell Park Cancer Institute in Buffalo, NY and her MBA from the Simon School at University of Rochester in Rochester, NY.