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Correcting Chromosomal Abnormalities in iPSCs via Chromosome Transplantation

Review of “Chromosome Transplantation: Correction of the Chronic Granulomatous Disease Defect in Mouse Induced Pluripotent Stem Cells” from STEM CELLS by Stuart P. Atkinson

Researchers from the laboratory of Marianna Paulis (Humanitas Clinical and Research Center, Rozzano, Milan, Italy) recently provided proof-of-principle for chromosome transplantation as an effective approach for the correction of structural chromosome abnormalities. Their exciting study replaced an Hprt‐defective X chromosome (which causes Lesch-Nyhan syndrome) with a wild type X chromosome in mouse embryonic stem cells [1]. 

The team now return with a new STEM CELLS study in which they extend their chromosome transplantation-based approach to genomic therapy to induced pluripotent stem cells (iPSCs) and the correction of Cybb gene abnormalities (which include large genomic deletions) that prompt the development of chronic granulomatous disease (CGD) [2]. CGD, an X‐linked severe immunodeficiency, is caused by the inability of immune cells to form the reactive oxygen compounds employed to kill pathogens. Overall, the team hopes that this strategy will allow for the correction of other aneuploidies, large deletions, and complex rearrangements that conventional gene therapy approaches such as CRISPR cannot currently tackle [3].

Following their previously reported protocol [1], Castelli et al. first inactivated the Hprt gene of the endogenous X chromosome by CRISPR/Cas9 technology in iPSCs derived from hematopoietic progenitors cells isolated from a CGD male mouse model [2]. This permitted the application of a hypoxanthine-aminopterin-thymidine selection system to introduce a normal donor X chromosome by microcell‐mediated chromosome transfer. Following the generation of X‐transplanted iPSC clones, the authors isolated diploid XY iPSCs that spontaneously lost the endogenous gene-modified X chromosome that carried the mutated Cybb/Hprt genes and then differentiated corrected iPSCs into functional Cybb-expressing granulocytes, the immune cells that protect the body against a range of microorganisms. While the efficiency of generating corrected iPSCs remained extremely low, the production of even a few iPSCs clones permits the generation of vast numbers of differentiated cells. 

While the authors readily admit that this strategy requires further development before reaching the clinic, they believe that their encouraging results represent a step forward for chromosome transplantation as a genomic therapy for diseases associated with aneuploidies, large deletions, and complex rearrangements. To this end, the authors point to improvements in microcell-mediated chromosome transfer that may permit chromosome transplantation in human iPSCs [4].

To keep up to date with chromosome transplantation and iPSC-based therapies, stay tuned to the Stem Cells Portal!

References

  1. Paulis M, Castelli A, Susani L, et al., Chromosome transplantation as a novel approach for correcting complex genomic disorders. Oncotarget 2015;6:35218-30.
  2. Pollock JD, Williams DA, Gifford MAC, et al., Mouse model of X–linked chronic granulomatous disease, an inherited defect in phagocyte superoxide production. Nature Genetics 1995;9:202-209.
  3. Castelli A, Susani L, Menale C, et al., Chromosome Transplantation: Correction of the Chronic Granulomatous Disease Defect in Mouse Induced Pluripotent Stem Cells. STEM CELLS 2019;37:876-887.
  4. Suzuki T, Kazuki Y, Oshimura M, et al., Highly Efficient Transfer of Chromosomes to a Broad Range of Target Cells Using Chinese Hamster Ovary Cells Expressing Murine Leukemia Virus-Derived Envelope Proteins. PLOS ONE 2016;11:e0157187.

Review ofChromosome Transplantation: Correction of the Chronic Granulomatous Disease Defect in Mouse Induced Pluripotent Stem Cellsfrom STEM CELLS by Stuart P. Atkinson

Researchers from the laboratory of Marianna Paulis (Humanitas Clinical and Research Center, Rozzano, Milan, Italy) recently provided proof-of-principle for chromosome transplantation as an effective approach for the correction of structural chromosome abnormalities. Their exciting study replaced an Hprt‐defective X chromosome (which causes Lesch-Nyhan syndrome) with a wild type X chromosome in mouse embryonic stem cells

[1]

.

The team now return with a new STEM CELLS study in which they extend their chromosome transplantation-based approach to genomic therapy to induced pluripotent stem cells (iPSCs) and the correction of Cybb gene abnormalities (which include large genomic deletions) that prompt the development of chronic granulomatous disease (CGD)

[2]

. CGD, an X‐linked severe immunodeficiency, is caused by the inability of immune cells to form the reactive oxygen compounds employed to kill pathogens. Overall, the team hopes that this strategy will allow for the correction of other aneuploidies, large deletions, and complex rearrangements that conventional gene therapy approaches such as CRISPR cannot currently tackle

[3]

.

Following their previously reported protocol

[1]

, Castelli et al. first inactivated the Hprt gene of the endogenous X chromosome by CRISPR/Cas9 technology in iPSCs derived from hematopoietic progenitors cells isolated from a CGD male mouse model

[2]

. This permitted the application of a hypoxanthine-aminopterin-thymidine selection system to introduce a normal donor X chromosome by microcell‐mediated chromosome transfer. Following the generation of X‐transplanted iPSC clones, the authors isolated diploid XY iPSCs that spontaneously lost the endogenous gene-modified X chromosome that carried the mutated Cybb/Hprt genes and then differentiated corrected iPSCs into functional Cybb-expressing granulocytes, the immune cells that protect the body against a range of microorganisms. While the efficiency of generating corrected iPSCs remained extremely low, the production of even a few iPSCs clones permits the generation of vast numbers of differentiated cells.

While the authors readily admit that this strategy requires further development before reaching the clinic, they believe that their encouraging results represent a step forward for chromosome transplantation as a genomic therapy for diseases associated with aneuploidies, large deletions, and complex rearrangements. To this end, the authors point to improvements in microcell-mediated chromosome transfer that may permit chromosome transplantation in human iPSCs

[4]

.

To keep up to date with chromosome transplantation and iPSC-based therapies, stay tuned to the Stem Cells Portal!

References

1.            Paulis M, Castelli A, Susani L, et al., Chromosome transplantation as a novel approach for correcting complex genomic disorders. Oncotarget 2015;6:35218-30.

2.            Pollock JD, Williams DA, Gifford MAC, et al., Mouse model of X–linked chronic granulomatous disease, an inherited defect in phagocyte superoxide production. Nature Genetics 1995;9:202-209.

3.            Castelli A, Susani L, Menale C, et al., Chromosome Transplantation: Correction of the Chronic Granulomatous Disease Defect in Mouse Induced Pluripotent Stem Cells. STEM CELLS 2019;37:876-887.

4.            Suzuki T, Kazuki Y, Oshimura M, et al., Highly Efficient Transfer of Chromosomes to a Broad Range of Target Cells Using Chinese Hamster Ovary Cells Expressing Murine Leukemia Virus-Derived Envelope Proteins. PLOS ONE 2016;11:e0157187.