Isolation and characterization of mesenchymal stem cells from human umbilical cord blood: reevaluation of critical factors for successful isolation and high ability to proliferate and differentiate to chondrocytes as compared to mesenchymal stem cells from bone marrow and adipose tissue.

Human umbilical cord blood (CB) is a potential source for mesenchymal stem cells (MSC) capable of forming specific tissues, for example, bone, cartilage, or muscle. However, difficulty isolating MSC from CB (CB-MSC) has impeded their clinical application. Using more than 450 CB units donated to two public CB banks, we found that successful cell recovery fits a hyper-exponential function of time since birth with very high fidelity. Additionally, significant improvement in the isolation of CB-MSC was achieved by selecting cord blood units having a volume ≥90 ml and time ≤2 h after donor's birth. This resulted in 90% success in isolation of CB-MSC by density gradient purification and without a requirement for immunoaffinity methods as previously reported. Using MSC isolated from bone marrow (BM-MSC) and adipose tissue (AT-MSC) as reference controls, we observed that CB-MSC exhibited a higher proliferation rate and expanded to the order of the 1 × 10(9) cells required for cell therapies. CB-MSC showed karyotype stability after prolonged expansion. Functionally, CB-MSC could be more readily induced to differentiate into chondrocytes than could BM-MSC and AT-MSC. CB-MSC showed immunosuppressive activity equal to that of BM-MSC and AT-MSC. Collectively, our data indicate that viable CB-MSC could be obtained consistently and that CB should be reconsidered as a practical source of MSC for cell therapy and regenerative medicine using the well established CB banking system.

Promising progression-free survival for patients low and intermediate grade lymphoid malignancies after nonmyeloablative umbilical cord blood transplantation.

Nonmyeloablative hematopoietic cell transplantation (HCT) has been used to treat patients with advanced or high-risk lymphoid malignancies. We studied 65 patients (median age 46 years) receiving an umbilical cord blood (UCB) graft after a single conditioning regimen consisting of cyclophosphamide (50 mg/kg) on day -6, fludarabine (40 mg/m(2)) daily on days -6 to -2, as well as a single fraction of total-body irradiation (TBI) (200 cGy) along with cyclosporine mycophenolate mofetil immunosuppression. Median time to neutrophil and platelet recovery was 7.5 days (range: 0-32) and 46 days (range: 8-111), respectively. Cumulative incidences of grade II-IV, grade III-IV acute, and chronic graft-versus-host disease (aGVHD, cGVHD) were 57% (95% confidence interval [CI]: 43%-70%), 25% (95% CI: 14%-35%), and 19% (95% CI: 9%-29%), respectively. Transplant-related mortality at 3 years was 15% (95% CI: 5%-26%). Median follow-up was 23 months. The progression free-survival (PFS), current PFS and overall survival (OS) were 34% (95% CI: 21%-47%), 49% (95% CI: 36%-62%), and 55% (95% CI: 42%-70%) at 3 years. Based on our data, we conclude that a nonmyeloablative conditioning regimen followed by UCB transplantation is an effective treatment for patients with advanced lymphoid malignancies who lack a suitable sibling donor.

Incidence, risk factors, and outcome of cytomegalovirus infection and disease in patients receiving prophylaxis with oral valganciclovir or intravenous ganciclovir after umbilical cord blood transplantation.

There is no information on the efficacy and safety of anticytomegalovirus (CMV) prophylaxis with intravenous ganciclovir or oral valganciclovir after unrelated cord-blood transplantation (UCBT). This issue was addressed in 151 adults (117 CMV-seropositive) undergoing UCBT at a single institution. The first 38 CMV-seropositive recipients were assigned to receive prophylactic ganciclovir, and the next 79 were given valganciclovir after engraftment. The cumulative incidence (CI) of CMV infection and disease was similar in patients receiving valganciclovir or ganciclovir (59% versus 55%, P = .59; and 9% versus 18%, P = .33, respectively). The toxicity profile and CI of nonrelapse mortality (CMV) and infection-related mortality did not differ between drugs. Patients receiving valganciclovir required fewer visits to the day hospital (P = .04). The CI of CMV infection and disease in 34 CMV-seronegative recipients was 12% and 6%, indicating that tight CMV monitoring is mandatory in this subset. The recipient's CMV serostatus, acute and extensive chronic graft-versus-host disease (aGVHD, cGVHD) were the main risk factors for CMV infection, and aGVHD for CMV disease. This study suggests that prophylaxis with oral valganciclovir is as safe and effective as intravenous ganciclovir for preventing CMV infection and disease after UCBT, but valganciclovir reduces the use of hospital resources.

Impact of hematopoietic chimerism at day +14 on engraftment after unrelated donor umbilical cord blood transplantation for hematologic malignancies.

BACKGROUND: Cord blood transplant is a feasible treatment alternative for adult patients with hematologic malignancies lacking a suitable HLA-matched donor. However, the kinetics of myeloid recovery is slow, and primary graft failure cannot be detected easily early after transplantation. We investigated the impact of hematopoietic chimerism status from unselected marrow cells 14 days after transplantation on predicting engraftment after a cord blood transplant. DESIGN AND METHODS: Seventy-one adult patients with hematologic malignancies undergoing single-unit unrelated donor cord blood transplantation after a myeloablative conditioning regimen were included in the study. All patients received conditioning regimens based on busulfan, thiotepa and antithymocyte globulin. Chimerism status was assessed analyzing short tandem repeat polymorphisms. RESULTS: The cumulative incidence of myeloid engraftment at 1 month was significantly lower in patients with mixed chimerism than in those with complete donor chimerism (55% vs. 94%; p<0.0001). For patients achieving myeloid recovery, the median time of engraftment was 16 days when donor chimerism at day + 14 was higher than 90%, compared with 24 days when donor chimerism was below this level (p<0.001). A donor chimerism level of 65% was found to be the best cut-off point for predicting primary graft failure, with a sensitivity of 97% and a specificity of 80%. The incidence of primary graft failure was 67% for patients with less than 65% donor chimerism at day +14 as compared to only 2% for those with more than 65% donor chimerism (p<0.001). Patients with mixed chimerism also had a lower cumulative incidence of platelet engraftment than those with complete chimerism (62% vs. 89%; p=0.01). CONCLUSIONS: Donor-recipient chimerism status at day +14 predicts engraftment after a single-unit cord blood transplant in adults.

A study of incidence and characteristics of infections in 476 patients from a single center undergoing autologous blood stem cell transplantation.

Infectious complications are a major cause of morbidity and mortality in patients who undergo autologous stem cell transplantation (ASCT). We examined 476 patients with hematologic malignancies (401) or solid tumors (75) who underwent ASCT between February 1990 and May 2005. Anti-infectious prophylaxis consisted of different combinations of ciprofloxacin, cotrimoxazole, fluconazole, aerosolized amphotericin B, acyclovir, and intravenous immunoglobulins. Overall, 454 patients (95%) developed fever in the first 60 days after ASCT. In the majority of patients, initial antibiotic therapy consisted of broad-spectrum beta-lactamic with or without amikacin. A glycopeptide was administered as initial therapy in 86 cases. Overall, there were 132 (29%) clinically documented infections (37 pneumonias), 79 (17%) microbiologically documented infections (65 bacteremias), and 243 (54%) fevers of unknown origin. Coagulase-negative staphylococci (18, 25%) and E coli (18, 25%) were the organisms most frequently isolated. The pattern of infection did not change throughout the study except for a significantly higher incidence of bacteremia due to gram-positive bacteria in the first 5 years of the study. Infection-related mortality was 5% (21 cases), with pneumonia the most frequent cause of death. ASCT should be considered a low-risk procedure, although new therapeutic approaches for patients developing severe respiratory infections are still needed.