Special model: Induced pluripotent stem cells
In 2006, a new technology was presented by Nobel Laureate Shinya Yamanaka to derive pluripotent stem cells from differentiated somatic cells without the need to isolate pre-implantation blastocysts. These induced pluripotent stem (iPS) cells can be generated by introducing a set of pluripotency-associated transcription factors into differentiated somatic cells, which modify their epigenetic status leading to cellular reprogramming. As pluripotent cells, iPS cells share main characteristics of embryonic stem cells such as the ability for unlimited self-renewal and the potential to differentiate into cells of the three germ layers layers mesoderm, endoderm and ectoderm. Since iPS cells can readily be derived from human cells, including fibroblasts from skin biopsies, this technology has significant implications for regenerative medicine and biomedical research. Indeed, the derivation of iPS cells from patients offers an invaluable opportunity to study disease pathogenesis in an in vitro-culture system on human cells at risk (e.g. neurons from a patient with a neurodegenerative disease), which is often difficult to accomplish in patients due to the unavailability of appropriate tissue (e.g. brain tissue of a patient). Our stem cell team works on the following topics.
1.) Improving the neural differentiation of human iPS cells
We use an optimized protocol to derive neural progenitor cells from human iPS cells (Figure 1A). These neural progenitor cells can be frozen, thawed and expanded over prolonged period of time without loosing the potential to differentiate into neuronal or glial cell types in vitro. By applying additional differentiation protocols, these neural progenitor cells can be further directed to differentiate into specialized neurons such as spinal cord motor neurons or midbrain dopaminergic neurons (Figure 1B). These specialized neurons provide an excellent cell source for cell therapy approaches or, when derived from patients with a neurodegenerative disease, for modelling of the underlying disorder in vitro. In addition to applying our neuronal differentiation protocols, our stem cell team is currently working on developing new methods to efficiently generate mature oligodendrocytes from our human neural progenitor cells in order to learn more about the biology of these cells in the context of neurological disorders.
2.) Applying patient-derived iPS cell for disease modelling in vitro
Initially, we have shown that iPS cells can be derived from Parkinson patients and that Parkinson patient-derived dopaminergic neurons survived and were functional after transplantation into a rodent model of Parkinson's disease (Figure 2). In collaboration with the Max Planck Institute for Molecular Biomedicine in Münster, we are currently deriving and characterizing iPS cells from patients with other neurodegenerative movement disorders. These iPS cells can be efficiently differentiated into specialized neuronal cell types in vitro as described above. Thus, we have the great opportunity study disease pathways in these patient-derived neurons that are not disturbed in neurons derived from iPS cells from healthy control individuals. The goal of this approach is to describe mechanisms of disease development and to find therapeutic targets in patient-derived neural cells.
- Hargus G, Cui Y, Schmid JS, Xu J, Glatzel M, Schachner M, Bernreuther C
Tenascin-R promotes neuronal differentiation of embryonic stem cells and recruitment of host-derived neural precursor cells after excitotoxic lesion of the mouse striatum. Stem Cells 26 (8): 1973-84 (2008)
- Soldner F, Hockemeyer D, Beard C, Gao Q, Bell GW, Cook EG, Hargus G, Blak A, Cooper O, Mitalipova M, Isacson O, Jaenisch R
Parkinson's disease patient-derived induced pluripotent stem cells free of viral reprogramming factors. Cell 136 (5): 964-77 (2009)
- Hargus G, Cooper O, Deleidi M, Levy A, Lee K, Marlow E, Yow A, Soldner F, Hockemeyer D, Hallett P, Osborn P, Jaenisch R, Isacson O
Differentiated Parkinson patient-derived iPS cells grow in the adult rodent brain and reduce motor asymmetry in Parkinsonian rats. Proc Natl Acad Sci USA 107 (36): 15921-6 (2010)
- Cooper O, Seo H, Andrabi S, Sundberg M, McLean J, Carrillo-Reid L, Xie Z, Osborn T, Hargus G, Deleidi M, Lawson T, Bogetofte-Thomasen H, Perez-Torres E, Clark L, Moskowitz C, Guardia-Laguarta C, Mazzulli J, Chen L, Volpicelli-Daley L, Romero N, Jiang H, Uitti RJ, Huang L, Opala G, Feng J, Ross OA, Trojanowski JQ, Lee V, Krainc D, Marder K, Pzedborski S, Surmeier J, Wszolek ZK, Dawson TM, Isacson O
Pharmacological Rescue of Mitochondrial Deficits in iPSC-Derived Neural Cells from Patients with Familial Parkinson's Disease. Science Translational Medicine, 4(141): 141ra90 (2012)
- Reinhardt P, Schmid B, Burbulla LF, Schöndorf DC, Wagner L, Glatza M, Höing S, Hargus G, Heck SA, Dhingra A, Wu G, Müller S, Brockmann K, Kluba T, Maisel M, Krüger R, Berg D, Tsytsyura Y, Thiel CS, Psathaki OE, Klingauf J, Kuhlmann T, Klewin M, Müller H, Gasser T, Schöler HR, Sterneckert J
Genetic correction of a LRRK2 mutation in human iPSCs links Parkinsonian neurodegeneration to ERK-dependent changes in gene expression. Cell Stem Cell, 7; 12 (3):354-67 (2013)