Has it really been 10 years since induced pluripotent stem cells (aka IPS cells or IPSC) came onto the scene in the stem cell field?
Yes, it was a decade ago that now Nobel Laureate Shinya Yamanaka (山中伸弥) published that seminal Cell paper on reprogramming to make mouse IPS cells and then human IPS cells came the next year.
From the moment I read that first mouse IPS cell paper, I was very excited about the science and the ideas in it. The domain name of this blog The Niche is named after those remarkable cells, www.ipscells.com.
In honor of the 10-year anniversary, below I outline the top 10 IPS cell related questions and key points as of today looking to the future.
- IPSC and ESC as partners rather than competitors. Are IPS cells equivalent to hESC derived from leftover IVF embryos? Even if they are a bit different, does that matter? With both in the translational pipeline and available as the basis for research, we can achieve more as a field. Let’s see what develops. Will nuclear transfer ES cells (NT-ESC) ever fulfill the aspirational name of their production,” therapeutic cloning”? Or will they mainly be a cool, but somewhat esoteric tool for advancing knowledge and one used by only a few groups in the world? I hope there can be clinical impact from NT-ESC, but I’m very doubtful that it will become a reality any time soon.
- IPS cell trials. How will clinical translation of IPS cell-based products proceed in the next 10 years and sooner? How soon will the Takahashi study get back up to speed in its new form? Will other trials get going relatively soon (i.e. in the coming 3-5 years)?
- Diseases in a dish. Disease modeling using IPS cells continues to grow in importance. Will it continue to give the cell therapy side of IPS cells a challenge in terms of total positive translational impact from IPS cells? So far I would say disease modeling has had more impact, but that could change.
- Auto and allo. Autologous versus allogeneic IPS cell approaches are both generating buzz. As to the latter, what about those IPS cell banks in various places?
- Mutations matter but here’s the key context. Do IPS cell mutations matter? Of course they could, but most likely in the same way that ES cell mutations do. It’s more a question of genomic stability in general. What about mitochondrial mutations in IPS cells? The key thing here overall with genome issues is careful preparation and handling of cells and validating them rigorously. That doesn’t always happen.
- IPS cell sex. What about female IPS cells? Can we somehow “put an X” through the problems that sometimes appear associated with loss of X inactivation in female IPS cells? What about issues with imprinted genes? We don’t hear much about these things lately. As with the previous point, the bigger issue is validation of anything stem cell-wise that you’re studying, particularly if you have clinical intent down the road. Epigenomic validation more generally is very important for IPS cells.
- Patent big tent? Putting the IP in IPS cells or taking it out? Will there be any patent disputes of major significance moving forward or clinical research that is impeded by expensive licensing fees…or not so much?
- Directed direction. Is direct reprogramming going to heat up more so that it becomes a major alternative to IPS cells in certain cases? I hope so. The more cell types and methods we have, the better as long as they are supported by rigorous data.
- A vision for vision and beyond. Will the eyes continue to have it? Will IPS cell therapy development go beyond vision-related conditions soon? I’m sure it will, but eye conditions are dominant now as a focus for products made from IPS cells and ES cells. I can’t wait to see more trials for other conditions.
- Differentiation destination. In nearly all cases IPS cells will themselves not be used for therapies. Instead, differentiated cells made from IPS cells will be the actual therapeutic product. As with ES cells, a challenge with IPS cells is consistently making pure differentiated cells of the desired type. For instance, if you make 98% of say a neuronal cell type that you want and 2% of some undefined mesoderm or endoderm cells, that’s going to be a hurdle to overcome. The goal of cellular purity and specificity achievable with human pluripotent stem cell differentiation, but it can also be a real challenge.
Overall, I predict the IPS cell field will continue to mature and have even more impact in the next decade. A growing fraction of that impact will hopefully be coming from cell therapy-based clinical trials. There are likely going to be bumps in the road and even setbacks in the coming decade, but overall I’m very optimistic about IPS cells.