I think eventually the field is going to move quite towards immune tolerance, whether it’s some kind of strategy to directly tolarize the host, or you can modify your stem cell product to remove some of the immunogenicity.
And then the reason I say that is… I think it’s definitely a very attractive idea to encapsulate the cells to block the immune response against the cells. But then you create these other problems like slowing the kinetics, and then some kind of oxygen limitation, you know if the oxygen can’t come in as fast then you cannot put as many cells in these devices. And so it’s a trade-off between these kind of safety concerns and that. I think a lot of the companies, they all want to address the safety, so they can go into the clinic a little faster. I think in the beginning you saw most companies say their main program is encapsulation, but then you now see that ViaCyte is working with CRISPR Therapeutics.
And so I would imagine that if they’re modifying the the cells for their immunogenicity, then I think the point will be not to encapsulate them.
Similarly I think Semma, which is now part of Vertex, I think they have also publicly said that they also have a non-encapsulation program. So I think they understand that biologically it makes more sense to have direct vascularization of the cells. I think it’s better for the long term durability of your cell graft and also better for their function. So I think eventually we will probably go the route of non-encapsulation.