2005 Fiscal Year Final Research Report Summary
Development of new and safer gene therapy method for severe combined immunodeficiency.
| Project/Area Number |
15390320
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Pediatrics
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| Research Institution | Tohoku University |
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Principal Investigator |
KUMAKI Satoru Tohoku University, Institute of Development, Aging and Cancer, Associate professor, 加齢医学研究所, 助教授 (20311566)
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| Co-Investigator(Kenkyū-buntansha) |
TSUCHIYA Shigeru Tohoku University, Graduate School of Medicine, Professor, 大学院・医学系研究科, 教授 (30124605)
SASAHARA Yoji Tohoku University, Institute of Development, Aging and Cancer, Assistant professor, 加齢医学研究所, 助手 (60372314)
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| Project Period (FY) |
2003 – 2005
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| Keywords | primary immunodeficiency / severe combined immunodeficiency / X-SCID / γc chain / gene therapy / suicide gene |
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| Research Abstract |
Gene therapy of SCID was efficient in correcting immunodeficiency. However, a severe adverse event, leukemia due to insertional mutagenesis by the retroviral vector, was reported in the X-SCID gene therapy clinical trial. Therefore, we performed studies aiming at developing safer gene therapy method. The main results are listed below.
1. To offset the side effect, we have incorporated a suicide gene into therapeutic retroviral vector for selective elimination of transduced cells. Cells from X-SCID patients were transduced with bicistronic retroviral vector carrying human γc chain cDNA and HSVtk gene. After confirmation of functional reconstitution of the γc chain, the cells were treated with ganciclovir (GCV). The γc chain positive cells were eliminated under low concentration without cytotoxicity on untransduced cells, and have not reappeared at least for 6 months. Furthermore, the γc chain transduced cells were still sensitive to GCV after six months. These results demonstrated the efficacy of the suicide gene therapy.
2. To minimize insertional mutagenesis, vector integration was targeted towards neutral DNA regions using phage φC31 integrase system. We demonstrate two preferable integration sites in human chromosomes 18p11.2 and 13q14.1 in hematopoietic cells. No integration in or close to known proto-oncogenes was observed.
3. We continue to perform molecular diagnosis of SCID using blood samples from all over Japan and South Korea. We have identified mutations in the genes encoding γc chain, Jak3, IL7Rα, RAG1 and Artemis.
Remarks : Preliminary experiment of "Gene therapy Clinical Trial of X-SCID" which had been approved by the Japanese government, was performed using a patient's bone marrow cells. However, the clinical trial has been postponed due to a report of the severe adverse event by the gene therapy.
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