Ex-vivo expanded umbilical cord blood stem cells retain capacity for myocardial regeneration.

BACKGROUND: Umbilical cord blood (UCB) is a source of human hematopoietic precursor cells (HPCs), a stem cell (SC) type that has been used in several trials for myocardial repair. A certain minimal number of cells is required for measurable regeneration and a major challenge of SC-based regenerative therapy constitutes ex-vivo expansion of the primitive cell compartment. The aim of this study was to investigate the ex-vivo expansion potential of UCB-derived HPCs and the ability of these expanded cells to migrate to the site of damage and improve ventricular function in a rodent model of myocardial infarction (MI). METHODS AND RESULTS: UCB-derived HPCs, defined by coexpression of CD133 and CD34, were expanded using various cytokine combinations. MI was induced by left anterior descending artery ligation in nude rats. Cells were injected intravenously 2 days after infarction. The combination of SC factor, thrombopoietin, flt3-ligand and interleukin-6 was found to be the most effective for inducing proliferation of HPCs. The migratory capacity of expanded HPCs was similar to that of non-expanded HPCs and improvement of ejection fraction was significant in both groups, with a relative increase of >60%. CONCLUSIONS: UCB-derived HPCs can be reproducibly expanded ex-vivo and retain their potential to improve cardiac function post-MI. (Circ J 2010; 74: 188 - 194).

Comparison of combined prophylaxis of cytomegalovirus hyperimmune globulin plus ganciclovir versus cytomegalovirus hyperimmune globulin alone in high-risk heart transplant recipients.

BACKGROUND: Seronegative heart transplant recipients who receive an allograft from seropositive donors have a higher risk of developing cytomegalovirus (CMV) disease and cardiac allograft vasculopathy (CAV) and dysfunction. Neither CMV-specific hyperimmune globulin nor ganciclovir as sole CMV prophylaxis is sufficient to prevent CMV disease in high-risk patients. We retrospectively evaluated the efficacy of CMV-hyperimmune globulin with and without ganciclovir in 207 D+/R- heart transplant recipients. METHODS: The study population was divided into two groups: Group A was composed of 96 patients who received CMV hyperimmune globulin as sole CMV prophylaxis, and group B was composed of 111 patients who received combined CMV prophylaxis. All recipients were subjected to quadruple cytolytic immunosuppression. Primary and secondary end points included prevention of CMV-associated death, CMV disease and productive infection, CAV, and overall infection. RESULTS: There was no difference in overall survival between the two groups. Four patients in the group A died of CMV sepsis, whereas no CMV-associated death was observed in group B (P =0.0326). The actuarial incidence of CMV disease was significantly lower in patients who received double CMV prophylaxis (32.29 vs. 11.71, P =0.0003). Although no difference was observed with regard to productive CMV infection (53.12 vs. 65.77, P =not significant), CAV and overall infection rates were significantly higher in the first group (7.29 vs. 0.9, P =0.0157 and 70.83 vs. 62.16, P =0.03, respectively). CONCLUSIONS: Double CMV prophylaxis consisting of CMV hyperimmune globulin and ganciclovir is able to abolish CMV death and prevent CMV disease in high-risk heart transplant recipients. Therefore, the use of a combination regimen is recommended for seronegative recipients with seropositive donors.