Development of biomarkers for human embryonic stem cell-derived neural progenitor cells and their derivatives
Gerwe, Brian Andrew
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The directed differentiation and isolation of human embryonic stem cell (hESC)-derived astrocytes would provide a cell source to further study a wide range of neurological disorders. Originally, morphology was used to distinguish astrocytes; however, the high content of intermediate filaments, particularly glial fibrillary acidic protein (GFAP), is now used to distinguish astrocytes. Herein, we study the temporal expression of GFAP, a developmental glial biomarker, to further elucidate the differentiation process of human neural progenitor (hNP) cells towards an astrocyte-like cell population. However, the temporal onset of neurogenesis precedes gliogenesis and is therefore difficult to study in culture. Moreover, the in vitro isolation of astrocytes from hESC sources still remains elusive but, once accomplished, would provide further characterization of astrocyte-mediated diseases. The current study utilizes lentiviral technology to stably integrate a tissue-specific reporter construct into hNP cells, thus enabling selective monitoring for the appearance of glial-like cells in differentiation cultures. The study demonstrated a dramatic transcriptional up regulation in GFAP expression when differentiation medium was supplemented with five and ten percent fetal bovine serum (FBS), illustrating a clear treatment effect. In addition, the scope of biomarker development was broadened with the application of high-throughput proteomics encompassing membrane fractionation and liquid-chromatography tandem mass spectrometry (LC-MS/MS) analysis to address custom biomarker screening (e.g. hESC line distinction). The membrane fraction of the human derived cell lines WA09, BG01, WA09-derived neural progenitor (hNP) cells and abBG02 (trisomy 12, 14, 17 and an extra copy of X chromosome) was successfully scanned, identifying cell surface markers unique to each line. This provided an important proof of concept, demonstrating the potential ability to delineate differentiated hESC lines and their derivatives. Cell surface marker discrimination based on high-throughput proteomics may provide a highly efficient technique to produce homogeneous populations. Therefore, it is of great importance to obtain new biomarkers that lead to basic research and clinical breakthroughs, characterization of disease pathologies and the development of novel diagnostics tools.