What Somatic Cell Types Can Be Reprogrammed into iPS Cells?
Most iPS cell lines established in earlier studies were derived from fibroblasts. Can iPS cells be established from other somatic cell types? If so, at what frequency? These questions were soon answered, although not completely. Using somatic cells harvested from transgenic mouse lines containing the four reprogramming transcription factors, several groups showed that iPS cell lines could be generated from different cell types, such as neuronal progenitor cells, keratinocytes, hepatocytes, B cells, and fibroblasts of mouse tail tips, kidneys, muscles, and adrenal glands. These results demonstrate the capacity of the four transcription factors to mediate reprogramming regardless of developmental origins and epigenetic states of a cell. The efficiency of cell reprogramming varies among different cell types. For example, human keratinocytes from skin biopsies can be reprogrammed to pluripotency at much higher frequency and faster speed than fibroblasts. This difference is attributed to th
