ISSN: 1449-1907International Journal of Medical Sciences
Global reach, higher impact
Int J Med Sci 2013; 10(5):522-531. doi:10.7150/ijms.5325 This issue Cite
Research Paper
IGF-1 Acts as Controlling Switch for Long-term Proliferation and Maintenance of EGF/FGF-responsive Striatal Neural Stem Cells
1. Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia;
2. Department of Medical Microbiology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia;
3. Department of Pediatrics, Baylor College of Medicine, TX 77030, USA;
4. Department of Pathology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
* Co-first authors.
Abstract
Background: Long-term maintenance of neural stem cells in vitro is crucial for their stage specific roles in neurogenesis. To have an in-depth understanding of optimal conditional microenvironmental niche for long-term maintenance of neural stem cells (NSCs), we imposed different combinatorial treatment of growth factors to EGF/FGF-responsive cells. We hypothesized, that IGF-1-treatment can provide an optimal niche for long-term maintenance and proliferation of EGF/FGF-responsive NSCs.
Objective: This study was performed to investigate the cellular morphology and growth of rat embryonic striatal tissue derived-NSCs in long-term culture under the influence of different combinatorial effects of certain growth factors, such as EGF, bFGF, LIF and IGF-1.
Methods: The NSCs were harvested and cultured from striatal tissue of 18 days old rat embryos. We have generated neurospheres from these NSCs and cultured them till passage 7 (28 days in vitro) under four different conditional microenvironments: (A) without growth factor, (B) EGF/bFGF, (C) EGF/bFGF/LIF, (D) EGF/bFGF/IGF-1 and (E) EGF/bFGF/LIF/IGF-1. Isolated NSCs were characterised by Immunoflouroscence for nestin expression. The cell growth and proliferation was evaluated at different time intervals (P1, P3, P5 & P7), assessing the metabolic activity based cell proliferation. Apoptosis was studied in each of these groups by In situ cell death assay.
Results: Our results demonstrated certain important findings relevant to long-term culture and maintenance of striatal NSC-derived neurospheres. This suggested that IGF-1 can induce enhanced cell proliferation during early stages of neurogenesis, impose long-term maintenance (up to passage 7) to cultured NSCs and enhance survival efficiency in vitro, in the presence of EGF and FGF.
Conclusions: Our findings support the hypothesis that the enforcement of IGF-1 treatment to the EGF/FGF-responsive NSCs, can lead to enhanced cell proliferation during early stages of neurogenesis, and an extended life span in vitro. This information will be beneficial for improving future therapeutic implication of NSCs, by addressing improved in vitro production of NSCs.
Keywords: neural stem cells, neurospheres, proliferative activity, EGF, bFGF, LIF, IGF-1.
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