Dr. Derrick Rossi

Cellular Reprogramming with mRNA

Luigi Warren, et.al., and Derrick J. Rossi (Nov. 2010) Highly Efficient Reprogramming to Pluripotency and Directed Differentiation of Human Cells with Synthetic Modified mRNA. Cell Stem Cell 7, 1–13. NOTE: Supplementary Material Included.

Review: Hanna JH, Saha K, Jaenisch R. Nov. 2010. Pluripotency and cellular reprogramming: facts, hypotheses, unresolved issues. Cell. 143(4):508-25.

Question 1: About Dr. Derrick Rossi

Dr. Rossi, can you please tell us a bit about yourself, your career path over the years and what led you to your work on cellular reprogramming? In addition, could you set the stage for our discussion today by providing us a brief historical account of the field of cellular reprogramming that led to your current study?

Michael Barresi

Question 2: Oxygen content and reprogramming efficiency

Why does reducing the oxygen content (Table 1) increase the efficiency of the reprogramming? Is there an oxidizing factor? Why does the presence of LIN28 “rescue” the loss of efficiency in higher oxygen environments?

Rachael Stein

Followup: What would be the difference between the reprogramming efficiency of RNA and Virus (KMOS) under low oxygen concentrations (hypoxic conditions)?

Jiyun Seo

Question 3: RiPSCs vs ESCs

In your paper, you compare RiPSC clones to fibroblasts, human ESCs, and virally-derived iPSC lines. Through several comparisons, it seemed to me that RiPSCs and human ESCs were the two best stem cells to be used. You describe how RiPSCs are very similar and comparable to human ESCs in many ways. How would you compare the potentials and hopes of the near future of both stem cells? Would you say one is better than the other? Can you also briefly tell us about the main differences between those two types of stem cells?

Sylvie Bae

Question 4: Application of methods

How soon do you think your methods will be applied in the field? Do you believe your current methods are practical in the consumer sense; if not, how long do you think it will be until someone improves upon them even further – to the point where they are practical?

Kim Chi Ngo

Question 4 Followup: Steps to use iPSC’s clinically

What still has to happen in order for us to be able to use induced pluripotent stem cells clinically and actually start curing diseases??

Carla Velez

Question 5: ES as golden standard cells

Can you discuss what one means when one says that ES cells are the gold standard in stem cell research? How do tests that are used to compare ES cells to reprogrammed cells differ in humans versus mice (such as the tetraploid complementation assay, which one could never perform using human cells for obvious reasons)? What would you say is the most stringent test for “stemness”? How much trust would you place in a cell that passed this test?

Christina Wright

Question 6: DNA alterations and impact on clinical IPSCs

In a recent article titled “Copy number variation and selection during reprogramming to pluripotency”, Otonkoski et al. claim that reprogramming can cause “genetic rearrangements and ‘copy number variations,’ which are alterations of DNA in which a region of the genome is either deleted or amplified on certain chromosomes.” How would this impact research or the therapeutic uses of these IPS cells?

Rachael Stein

Question 7: hESC funding and iPSC research 

Regarding the current court case, do you think that hESC research detracts from funding that could go towards iPSC research?

Sofia Annis

Question 8: Most pressing questions in cellular reprogramming field

To end our discussion today can you please comment on what you feel are some of the most pressing questions remaining to be answered in the field of cellular reprogramming and what part your lab is playing in addressing these questions?

Michael Barresi

Question 9

If you could say only one word or phrase about regenerative medicine, what would that word or phrase be?

Nguyen Huynh