How different are tissue-specific fibroblasts from each other?

Population proliferation limit and cell senescence?

• I am trying to understand the importance of proliferation limits and cell senescence. In particular, one of my homework questions is asking to compare the proliferation limit of Embryonic Stem cells (ES) and fibroblasts (which would be trans-differentiated) and describe how this difference plays a role when thinking about engineering organs, for example a heart transplant. Any help? How do ES cells and fibroblasts compare with regards to the Hayflick limit? ______________________________________... Here is what I am thinking, however I am not sure if this is correct or not. Non-differentiated the ES cells can divide almost indefinitely, however when the stem cell differentiates into a specific function, it goes through approximately 50 cell divisions before senescence. On the other hand, fibroblasts have already gone through some cell divisions at the point when they are trans-differentiated. Therefore, their life before senescence is less than 50 cell divisions. Can someone verify this?

• Answer:

  You are definitely thinking on the right lines. The ES, being pluripotent, has a much higher proliferation ability than the fibroblast. In term of tissue engineering, use of ES is definitely desirable for two reasons. One and most important, they are pluripotent meaning they can be induced to differentiate into almost any cell type required (if given the proper stimuli). Secondly, them being stem cells they have renewal capacity that would make maintaining lines possible. Self-renewal is an important property of the ES that makes them useful in this field of research. Hope that helped.