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Published on: October 28, 2014
Reprogramming IgH isotype-switched B cells to functional-grade induced pluripotent stem cells
Duane R Wesemann1, Andrew J Portuguese, Jennifer M Magee
1Program in Cellular and Molecular Medicine and Immune Disease Institute, Boston Children's Hospital, Boston, MA 02115, USA. wesemann@idi.harvard.edu
Summary
Reprogramming activated B cells into induced pluripotent stem cells (iPSCs) can be improved by inhibiting DNA methylation. This method overcomes epigenetic silencing, enabling iPSCs to generate high-grade chimeric mice.
Area of Science:
- Stem Cell Biology
- Immunology
- Epigenetics
Background:
- Induced pluripotent stem cells (iPSCs) are crucial for regenerative medicine but often face challenges with developmental potency.
- Epigenetic silencing of the Dlk1-Dio3 gene cluster in iPSCs derived from B cells hinders their ability to form high-grade chimeras.
- B cell activation via anti-CD40 and IL-4 induces class-switch recombination (CSR), leading to permanent IgH locus deletions.
Purpose of the Study:
- To investigate methods for reprogramming activated B cells into iPSCs with enhanced developmental potency.
- To overcome epigenetic silencing of the Dlk1-Dio3 locus in B cell-derived iPSCs.
- To enable B cell-derived iPSCs to contribute to high-grade chimerism in mice.
Main Methods:
- Activated splenic B cells were treated with anti-CD40 plus IL-4 to induce Ig heavy-chain (IgH) class-switch recombination (CSR).
- The methyltransferase inhibitor 5-aza-2'-deoxycytidine was used to attenuate hypermethylation of the Dlk1-Dio3 locus during reprogramming.
- Reprogrammed iPSCs were assessed for their ability to form high-grade chimeras in mice.
Main Results:
- B cells activated with anti-CD40 plus IL-4 produced iPSCs with hypermethylated Dlk1-Dio3 loci, failing to form chimeras.
- Treatment with 5-aza-2'-deoxycytidine before and during reprogramming attenuated Dlk1-Dio3 hypermethylation in resultant iPSCs.
- This treatment enabled B cell-derived iPSCs to form high-grade chimeras, with all mature B cells derived from IgG1-expressing iPSCs.
Conclusions:
- Culture conditions and epigenetic modifications significantly influence the developmental potency of B cell-derived iPSCs.
- Inhibiting DNA methylation during reprogramming is a viable strategy to enhance the contribution of B cell-derived iPSCs to chimerism.
- This approach provides a novel method for generating potent iPSCs from activated B cells for potential therapeutic applications.
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