Abstract

The growth, differentiation, and survival of normal hematopoietic stem cells as well as bone marrow (BM) cancer cells are regulated closely by the BM microenvironment. In case of lymphoma, recent study has demonstrated that the endothelial cells (not lymphoma cells) in the lymphoma microenvironment have the same chromosomal abnormality to that of lymphoma cells themselves. Besides, in our prior study, the mesenchymal stem cells (MSCs) isolated from BM of patients with various hematological malignancies may have different surface antigens expression as comparing to normal control (Leukemia, 2005, doi:10.1038/sj.leu.2403795, published online 19 May 2005). We therefore hypothesize that the MSCs isolated from BM of patients with hematological malignancies are “different” to those of normal and may probably has the same chromosomal abnormality as to that of the hematological cancer cells. In this study, cytogenetic studies were performed on both BM-blood cells and BM-derived MSCs at the same time by using method of conventional G-banding. At submission of this abstract, we have just examined 4 specimens obtained from patients of various diseases as well as normal adult (see table). Surprisingly, we identified a new chromosomal translocation, t(3;9)(q25;q31), on the BM-derived MSCs of a patient (Case 1 of the table, Figure 1) with acute promyelocytic leukemia harboring t(15;17) on the BM blood cells. Besides, a complex chromosomal abnormalities was found in a male patient of AML (Case 2 of the table, Figure 2). Though he has received a successful allotransplant 2 years ago and the BM blood cells had completely converted to donor type (normal 46 XX), the BM-derived MSCs were still recipient in origin and having a chromosomal abnormality that was different to the BM blood cells (45, -Y) at initial diagnosis of AML. BM-derived MSCs from a patient of CML and normal adult were normal. It is still too early to making a solid conclusion at present and we are now analyzing more specimens to look into the phenomenon we found. However, this is a new field in leukemic research that deserved further investigation and our novel finding indicates that abnormal cells (another clone?) may present in the BM stroma of patients with hematological malignancies.

Chromosomes of BM-blood cells and MSCs

Case No. Diseases Chromosomes of BM-blood cells Chromosomes of BM-MSCs 
Case 1 APL, at diagnosis 46 XX, t(15;17)(q21;q11) 46 XX, t(3;9)(q25;q31). (see figure 1) 
Case 2 AML (45, -Y at diagnosis), after allotransplant Normal 46 XX (male patient, female donor) 46 XY, t(7;22)(p22;q11); del(13)(q12q22); del(15)(q15?). (see figure 2) 
Case 3 CML, at diagnosis 46 XY, t(9;22)(q34;q11) Normal 46 XY 
Case 4 Normal adult Normal 46 XY Normal 46 XY 
Case No. Diseases Chromosomes of BM-blood cells Chromosomes of BM-MSCs 
Case 1 APL, at diagnosis 46 XX, t(15;17)(q21;q11) 46 XX, t(3;9)(q25;q31). (see figure 1) 
Case 2 AML (45, -Y at diagnosis), after allotransplant Normal 46 XX (male patient, female donor) 46 XY, t(7;22)(p22;q11); del(13)(q12q22); del(15)(q15?). (see figure 2) 
Case 3 CML, at diagnosis 46 XY, t(9;22)(q34;q11) Normal 46 XY 
Case 4 Normal adult Normal 46 XY Normal 46 XY 

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