Human progenitor cells isolated from the developing cortex undergo decreased neurogenesis and eventual senescence following expansion in vitro

Abstract

Isolation of a true self-renewing stem cell from the human brain would be of great interest as a reliable source of neural tissue. Here, we report that human fetal cortical cells grown in epidermal growth factor expressed low levels of telomerase and telomeres in these cultures shortened over time leading to growth arrest after 30 weeks. Following leukemia inhibitory factor (LIF) supplementation, growth rates and telomerase expression increased. This was best demonstrated following cell cycle synchronization and staining for telomerase using immunocytochemistry. This increase in activity resulted in the maintenance of telomeres at approximately 7 kb for more than 60 weeks in vitro. However, all cultures displayed a lack of oligodendrotye production, decreases in neurogenesis over time and underwent replicative senescence associated with increased expression of p21 before 70 weeks in vitro. Thus, under our culture conditions, these cells are not stable, multipotent, telomerase expressing self-renewing stem cells. They may be more accurately described as human neural progenitor cells (hNPC) with limited lifespan and bi-potent potential (neurons/astrocytes). Interestingly, hNPC follow a course of proliferation, neuronal production and growth arrest similar to that seen during expansion and development of the human cortex, thus providing a possible model neural system. Furthermore, due to their high expansion potential and lack of tumorogenicity, these cells remain a unique and safe source of tissue for clinical transplantation.

Transplantation of umbilical cord–derived mesenchymal stem cells as a novel strategy to protect the central nervous system: technical aspects, preclinical studies, and clinical perspectives

“…However, NSCs display decreased neurogenesis and senescence over time in culture (34) and harvesting them from brain tissue is difficult and raises ethical issues. NSCs can also be derived from ESCs, but the potential of ESCs is hampered by ethical questions.…”

Gene therapy-mediated delivery of targeted cytotoxins for glioma therapeutics

“…21505). Human neural progenitor cell cultures were prepared from freshly dissected fetal brain cortical tissue as previously described (30)(31)(32). For a brief description, see SI Appendix, SI Materials and Methods.…”

Specification of functional neurons and glia from human pluripotent stem cells

“…Fetal neural stem cells neither are ideal because of the ethical concerns of destroying fetus. In addition, although both adult and fetal neural stem cells in theory are able to be amplified using mitogens such as FGF2 or EGF, these neural stem cells always undergo undesired differentiation and tend to lose their potential to generate the appropriate type of cells for cell replacement therapy (Wright et al, 2006). Functional neurons (Vierbuchen et al, 2010;Ambasudhan et al, 2011;Marro et al, 2011;Pang et al, 2011;Qiang et al, 2011;Yoo et al, 2011), and lately subtype-specific neurons such as dopaminergic neurons (Caiazzo et al, 2011;Pfisterer et al, 2011) and motor neurons (Son et al, 2011) have been converted directly from other type of somatic cells of mouse and human by introducing pro-neuronal transcription factors or micro-RNA.…”