Sternal bone marrow is a suitable autologous cell source for cardiac stem cell therapies

Background: Autologous intramyocardial transplantation of CD133 positive bone marrow derived stem cells (BMSC) is currently investigated in cardiac regenerative therapy. Since sternal bone marrow is readily accessible during cardiac surgery procedures, it might be a suitable source for autologous stem cell harvest. However, little is known about the factors influencing stem cell yield and quality after sternal bone marrow aspiration.

Material and methods: Between 09/2012 and 09/2012 sternal bone marrow was harvested from 39 cardiac surgery patients after informed consent and CD133/CD34 double positive endothelial progenitor cells (EPC) were isolated. Patients were divided into two groups (Group A: N = 18, 09/12-04/12; Group B: N = 21, 07/13-09/13). Harvesting and isolation protocols were refined between the two series. In Group B stem cell yield was additionally correlated with clinical data.

Results: Groups did not differ in age (P = 0.92). Total volume of harvested bone marrow and CD133 positive BMSC yield per ml BM was significantly higher in Group B (Volume [ml]: Group A = 113 ± 13, Group B = 169 ± 32, P < 0.0001; cell yield [CD133 positive cells/ml BM]: Group A = 3.5*10^3 ± 2.3*10^3; Group B = 7.8*10^3 ± 3.6*10^3, P < 0.0001). Total amount of CD133 positive cells was 0.3 ± 0.2*10^6 in Group A and 1.0 ± 0.5*10^6 in Group B, respectively (P < 0.0001). Cell vitality after separation was 95 ± 4%. Total cell amount tended to decreased with age (Group B, R² = 0.43, P = 0.001) and Euroscore (Group B, R² = 0.19, P = 0.045).

Discussion: After meticulously establishing harvesting techniques and separation protocols, sternal bone marrow is a suitable autologous BMSC source for cardiac regenerative therapies with sufficient cell yield and vitality. With automated GMP conform separators available in the near future cell therapy and cardiac operation could be combined in one procedure, limiting cell handling and transportation.