-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

1896 Attempt to Prove the Existence of Abnormal B Lymphocyte As Myeloma-Initiating Cells from B Cell-Derived Induced Pluripotent Stem Cells

Program: Oral and Poster Abstracts
Session: 651. Myeloma: Biology and Pathophysiology, excluding Therapy: Poster I
Hematology Disease Topics & Pathways:
Diseases, multiple myeloma, smoldering myeloma, B-Cell Lymphoma, Plasma Cell Disorders, Lymphoid Malignancies
Saturday, December 1, 2018, 6:15 PM-8:15 PM
Hall GH (San Diego Convention Center)

Aki Yanagi, MS1*, Naohiro Tsuyama, PhD1*, Yukari Yanai, MS1*, Yu Abe, PhD1*, Misaki Sugai, BS1*, Akinobu Ota, PhD2*, Karnan Sivasundaram, PhD3*, Tomonari Shigemura, MD, PhD4*, Megumi Sasatani, PhD5*, Kenji Kamiya, MD, PhD5*, Ichiro Hanamura, MD, PhD6*, Takayuki Ikezoe, MD, PhD7, Masafumi Onodera, MD, PhD8* and Akira Sakai, MD, PhD1

1Dept. of Radiation Life Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
2Department of Biochemistry, Aichi Medical University, Nagakute, Japan
3Dept. of Hematology, Aichi Medical University School of Medicine, Nagakute, Japan
4Dept. of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
5Dept. of Experimental Oncology, RIRBM, Hiroshima University, Hiroshima, Japan
6Division of Hematology, Department of Internal Medicine, Aichi Medical University, Nagakute, Japan
7Dept. of Hematology, Fukushima Medical University School of Medicine, Fukushima, Japan
8Dept. of Genetics, National Research Institute for Child Health and Development, Tokyo, Japan

We previously established normal B cell-derived induced pluripotent stem cells (BiPSCs; BiPSC13 and MIB2-6). BiPSCs are known to maintain VDJ rearrangement of the IgH gene, and they can be induced by the tet-off system to express activation-induced cytidine deaminase (AID; BiPSC13-AID and MIB2-6-AID) and differentiate into hematopoietic progenitor cells (HPCs) (Scientific Rep, 2017). Using these BiPSCs, we attempted to prove the existence of abnormal B cells, which are thought to be myeloma-initiating cells, originating from mature B cells transformed by reprogramming. We speculated that BiPSCs could develop into myeloma-initiating cells that undergo chromosomal translocation or gain genetic abnormalities during redifferentiation into mature B cells. First, using the comet assay, we confirmed the DNA-damaging effect of AID in BiPSCs-AID. Secondly, we differentiated BiPSC13-AID into CD34+/CD38-/CD43-/CD45- cells by co-culture with stromal cells (mouse embryo cell line: 10T1/2), and we subsequently transplanted the cells into the bone marrow (BM) of immunodeficient NRG mice. The presence of CD34+ cells was still observed in mouse BM 4 months after transplantation; however, no differentiation into B cells was detected. Next, using the CRISPR/Cas9 system, we attempted to make BiPSCs with chromosomal translocation t(11;14); we succeeded in establishing a 293T cell line with t(11;14), then confirmed t(11;14) in MIB2-6-AID, and the clone is now being established. Furthermore, we established BiPSC13-Pax5, which can be induced by the tet-off system to express Pax5, and we then differentiated BiPSC13-Pax5 into CD34+/Pax5+/CD38-/CD43-/CD45- cells by co-culture with stromal cells (10T1/2). We expect that the HPCs or hematopoietic stem cells (HSCs) derived from BiPSCs will further differentiate into B cells due to the expression of Pax5 in the BM of NRG mouse. We also established BiPSC13-AID-p53-/-, in which p53 was deleted using the CRISPR/Cas9 system, and the cells differentiated into HPCs. Interestingly, we detected some CD43+/CD45+ cells among CD34+/CD38- cells after the co-culture of BiPSC13-AID with aorta-gonad-mesonephros-derived stromal cell (AGM-S3) instead of 10T1/2. Therefore, AGM-S3 may promote the differentiation of BiPSCs into cells that are more similar to HSCs. These CD34+ cells differentiated from BiPSCs will be transplanted into the BM of NRG mouse.

Disclosures: Hanamura: CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding; Kyowa Hakko Kirin Company, Limited: Research Funding; Fujimoto Pharmaceutical Corporation: Research Funding; Takeda Pharmaceutical Company Limited.: Other: Lecture fee; Bristol-Myers Squibb: Other: Lecture fee, Research Funding; Celgene: Other: Lecture fee.

*signifies non-member of ASH