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ȣ - 490863 133 |
| Cardiac SP cells have different characteristics distinct from bone marrow SP cells |
| Department of Cardiology, College of Medicine, Korea University, Seoul, Korea |
| Seung-Cheol Choi, Jihyun Yoon, Chi-Yeon Park, Ji-Hyun Choi, Young-Hoon Kim, Wan-Joo Shim, Young-Moo Ro, Do-Sun Lim |
Side population (SP) cells, characterized by their ability to efflux Hoechst 33342, has been identified with characteristics of stem cells in a number of tissues. Recent evidence suggests that the heart possesses cardiac stem cells that are clonogenic, self-renewing and multipotent. Here, we demonstrate that cardiac SP cells have different characteristics distinct from bone marrow SP cells. SP cells isolated from bone marrow and heart of C57BL/6 (6 to 8-wk-old) mice were analyzed by flow cytometry, RT-PCR and real-time RT-PCR. In vitro migration assay was performed in the presence or absence of 20 ng/ml HGF, 100 ng/ml SDF-1 and 20 ng/ml VEGF for 6h. One × 104 SP cells prepared from bone marrow or heart were cultured in Methocult medium for hematopoietic colony assays in the presence or absence of 20 ng/ml HGF or 100 ng/ml SDF-1 for 14 days. Flow cytometry analysis showed that cardiac SP cells are immunophenotypically different from bone marrow SP cells in Sca-1 (bone marrow vs. heart = 71.61±11.07% vs. 91.99±1.73%), c-kit (bone marrow vs. heart = 27.73±3.87% vs. 9.60±4.05) and CD45 expression (bone marrow vs. heart = 98.44±1.38 vs. 11.67±4.83), respectively. A number of hematopoietic colonies were formed in bone marrow SP cells (control:143.6±4.9 vs. HGF:137.6±4.4 vs. SDF-1α: 175.3±2.5), whereas adult heart SP cells only gave rise to less than 5 colonies. RT-PCR and real-time RT-PCR demonstrated that adult heart SP cells expressed cardiac transcription factors such as Nkx2.5, Gata4 and atrial natriuretic factor. Bone marrow stem cells strongly expressed angiogenic factors such as angiogenin-1, angiogenin-2 and VEGF, and CXCR4 molecule involved in stem cell mobilization. Using dual-chamber migration assays, we determined that bone marrow SP cells migrate in response to only SDF-1α (control:20.6±4.3 vs. HGF:18.6±1.4 vs. SDF-1α: 38.5±8.8 vs. VEGF:19.2±5.2), consistent with a high level of expression of CXCR4. However, adult heart SP cells didn’t show the migratory response to cytokines. In conclusion, these results demonstrate that cardiac SP cells have the potential for cardiac differentiation whereas bone marrow SP cells possess more committed capacity for neovascularization.
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