Defining the Isoform-Specific Effects of Apolipoprotein E on the Development of iPS Cells into Functional Neurons in Vitro and in Vivo

Defining the Isoform-Specific Effects of Apolipoprotein E on the Development of iPS Cells into Functional Neurons in Vitro and in Vivo

Funding Type: 
New Faculty II
Grant Number: 
RN2-00952
Award Value: 
$2,843,770
Disease Focus: 
Stroke
Neurological Disorders
Stem Cell Use: 
iPS Cell
Cell Line Generation: 
iPS Cell
Status: 
Active
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 

Year 1

The goal of this proposal is to determine the isoform-specific effects of apolipoprotein (apo) E on the development of induced pluripotent stem (iPS) cells into functional neurons both in vitro and in mice. Toward this goal, we have made significant progress in Aims 1 and 2. First, we further demonstrated that neural stem cells (NSCs) express apoE. ApoE-KO mice had significantly less hippocampal neurogenesis, but significantly more astrogenesis, than wildtype mice due to decreased Noggin expression in NSCs. In contrast, neuronal maturation in apoE4 knock-in (apoE4-KI) mice was impaired due to reduced survival and function of GABAergic interneurons in the hilus of the hippocampus, and a GABAA receptor potentiator rescued the apoE4-associated decrease in hippocampal neurogenesis. Thus, apoE plays an important role in hippocampal neurogenesis, and the apoE4 isoform impairs GABAergic input to newborn neurons, leading to decreased neurogenesis. A paper describing these data was published in Cell Stem Cell (Li G. et al. 2009, 5:634-645), which evidently is the 400th publication of CIRM-funded projects. Second, we established mouse iPS cell lines from adult mouse fibroblasts of wildtype, apoE knockout (apoE-KO), human apoE2-KI, human apoE3-KI, and human apoE4-KI mice. Finally, we developed NSC lines from mouse iPS cells with different apoE genotypes (wildtype mouse apoE, apoE-KO, apoE2, apoE3, and apoE4). These cell lines will be used to study the effects of apoE isoforms on neuronal development in vitro in culture and in vivo in mouse models.

Year 2

The goal of this proposal is to determine the isoform-specific effects of apolipoprotein (apo) E on the development of induced pluripotent stem (iPS) cells into functional neurons both in vitro and in mice. Toward this goal, we have made significant progress in the past year, as summarized below. First, We developed human iPS cells from skin fibroblasts of individuals with different apoE genotypes. We are fully characterizing these human iPS cell lines. Second, We are establishing neural stem cell (NSC) lines from human iPS cells with different apoE genotypes. Some of the NSCs have been maintained in monolayer cultures for many generations. These NSCs will be used to study the effects of apoE isoforms on neuronal development in vitro in cultures and in vivo in mice. Finally, we demonstrated that mouse apoE4-NSCs generated significantly fewer total neurons and fewer GABAergic interneurons than mouse apoE3-NSCs in culture. Thus, the detrimental effects of apoE4 on neurogenesis and GABAergic interneuron survival, as we observed in vivo in apoE4 knock-in mice (Li G. et al. Cell Stem Cell, 2009, 5:634-645), are recapitulated in cultures of mouse iPS cell–derived NSCs in vitro.

Year 3

The goal of this proposal is to determine the isoform-specific effects of apolipoprotein (apo) E on the development of induced pluripotent stem (iPS) cells into functional neurons both in vitro and in mice. Toward this goal, we have made significant progress in all three aims in the past year, as summarized below. 1) We have fully characterized two apoE3/3-hiPS cell lines and two apoE4/4-iPS cell lines. 2) We have established NSC lines from human iPS cells with an apoE3/3 or apoE4/4 genotype. The hNSCs have been maintained in suspension or monolayer culture for multiple passages. 3) We demonstrated that apoE4-hNSCs generated ~50% fewer GABAergic interneurons than apoE3-hNSCs in culture. Thus, the detrimental effects of apoE4 on GABAergic interneuron survival, as we observed in vivo in apoE4 knock-in mice (Li G. et al. Cell Stem Cell, 2009, 5:634-645), are recapitulated in cultures of human iPS cell-derived NSCs in vitro. 4) We established protocols in our lab to differentiate human iPS cell-derived NSCs into different types of neurons in cultures.

Year 4

The goal of this proposal is to determine the isoform-specific effects of apolipoprotein (apo) E on the development of induced pluripotent stem (iPS) cells into functional neurons both in vitro and in mice. Toward this goal, we have made significant progress in all three aims in the past year, as summarized below. 1) We demonstrated that apoE4-miPSC-derived mNSCs had a greater “age-dependent (passage-dependent)” decrease in generation and/or survival of MAP2-positive neurons in cultures. 2) We also demonstrated that apoE4-miPSC-derived mNSCs had an even greater “age-dependent (passage-dependent)” decrease in generation and/or survival of GAD67-positive GABAergic neurons, as seen in vivo in apoE4 knock-in mice (Li et al., Cell Stem Cell, 2009, 5:634–645). 3) We expanded the pilot study reported last year and confirmed the detrimental effect of apoE4 on GABAergic interneuron development/survival of hiPS cell-derived hNSCs. ApoE4 also increased tau phosphorylation, one of the pathological hallmarks of Alzheimer’s disease, in neurons derived from apoE4-hiPS cells. 4) We established a protocol to transplant apoE-miPS cell-derived mNSCs into mouse brains. The transplanted apoE-mNSCs developed into neurons and astrocytes and integrated into the neural circuitry.

Year 5

The goal of this proposal is to determine the isoform-specific effects of apolipoprotein (apo) E on the development of pluripotent stem cells into functional neurons in vitro in culture and in vivo in mice for potential cell replacement therapy. Toward this goal, we have made significant progress in all three aims in the past year, as summarized below. 1) We demonstrated that mouse GABAergic progenitors transplanted into the hilus of apoE3-KI and apoE4-KI mice developed into mature interneurons and functionally integrated into the hippocampal circuitry. 2) We also demonstrated that transplantation of mouse GABAergic progenitors into the hilus of apoE4-KI mice rescued learning and memory deficits. 3) Transplantation of mouse GABAergic progenitors into the hilus of hippocampus also rescued learning and memory deficits in apoE4-KI mice expressing Alzheimer’s disease-causing APP mutations.

© 2013 California Institute for Regenerative Medicine