Rucha V. Modak Author Answered Jun 19, 2022
Hematology and Medical Oncology, Oregon Health and Science University, 2019-0
Many thanks for reaching out. My mentor and I discussed this and we think this is indeed a very good question. Unfortunately, we cannot give you a clear answer.
We noticed this issue as well and wondering how such a second population may develop. Since GFP is a tremendously stable protein, once a cell expresses it, the cell will retain high levels of GFP for a long period of time. As stellate cells are constantly replenished, the cells with lower expression might be recently divided cells. Alternatively, some of the cells could have been activated during the isolation process. Such cells express higher levels of PDGFRb and, consequently, may express higher levels of GFP.
Thus, taken together, we noticed this issues but have not followed it up in more detail. Nonetheless, we would like to caution any hasted conclusions based on GFP expression alone.