Mesenchymal stromal cell mitochondrial transfer to human induced T-regulatory cells mediates FOXP3 stability.

The key obstacle to clinical application of human inducible regulatory T cells (iTreg) as an adoptive cell therapy in autoimmune disorders is loss of FOXP3 expression in an inflammatory milieu. Here we report human iTreg co-cultured with bone marrow-derived mesenchymal stromal cells (MSCs) during short-term ex vivo expansion enhances the stability of iTreg FOXP3 expression and suppressive function in vitro and in vivo, and further that a key mechanism of action is MSC mitochondrial (mt) transfer via tunneling nanotubules (TNT). MSC mt transfer is driven by mitochondrial metabolic function (CD39/CD73 signaling) in proliferating iTreg and promotes iTreg expression of FOXP3 stabilizing factors BACH2 and SENP3. These results elucidate cellular and molecular mechanisms underlying human MSC mt transfer to proliferating cells. MSC mt transfer stabilizes FOXP3 expression in iTregs, thereby enhancing and sustaining their suppressive function in inflammatory conditions in vitro and in vivo.

Worldwide Network for Blood and Marrow Transplantation (WBMT) recommendations for establishing a hematopoietic cell transplantation program (Part I): Minimum requirements and beyond.

Hematopoietic cell transplantation (HCT) is a highly complex procedure that requires a dedicated multidisciplinary team to optimize its safety. In addition, institutions may have different needs regarding indications based on regional disease prevalence or may have an interest in developing specialized services. Yet, structured recommendations are not commonly available. Here, the Transplant Center and Recipient Issues Standing Committee for the Worldwide Network for Blood and Marrow Transplantation (WBMT) organized a structured review of all pertinent elements to establish a transplant program. First, we solicited components from committee members and grouped them in domains (infrastructure, staff, cell processing laboratory, blood banking, laboratory, radiology, pharmacy, HLA testing, ancillary services and quality). Subsequently, reviewers scored all elements on a 7-point scale, from an absolute requirement (score of 1) to not required (score of 7). An independent group of five experienced transplant physicians reviewed the rankings. Minimum requirements to establish any HCT program were identified among elements with mean score of ≤2.0, and specific elements for allogeneic and autologous HCT were identified. Mean scores >2.0-4.0 were classified as preferred recommendation, and mean scores of >4.0 to ≤7.0 were considered ideal recommendations for advanced and complex types of transplantation. This structured set of recommendations guides the prioritization of minimum requirements to establish a transplant program and to set the path for expansion and further development.

Worldwide Network for Blood and Marrow Transplantation Recommendations for Establishing a Hematopoietic Cell Transplantation Program, Part I: Minimum Requirements and Beyond.

Hematopoietic cell transplantation (HCT) is a highly complex procedure that requires a dedicated multidisciplinary team to optimize safety. In addition, institutions may have different needs regarding indications based on regional disease prevalence or may have an interest in developing specialized services. Structured recommendations are not commonly available, however. The Transplant Center and Recipient Issues Standing Committee of the Worldwide Network for Blood and Marrow Transplantation (WBMT) organized a structured review of all pertinent elements for establishing a transplantation program. First, we solicited components from committee members and grouped them into domains (infrastructure, staff, cell processing laboratory, blood banking, laboratory, radiology, pharmacy, HLA testing, ancillary services, and quality). Subsequently, reviewers scored each element on a 7-point scale, ranging from an absolute requirement (score of 1) to not required (score of 7). An independent group of 5 experienced transplantation physicians reviewed the rankings. The minimum requirements for establishing any HCT program were identified among elements with mean score of ≤2.0, and specific elements for allogeneic and autologous HCT were identified. Mean scores of >2.0 to 4.0 were classified as preferred recommendation, and mean scores of >4.0 to ≤ 7.0 were considered ideal recommendations for advanced and complex types of transplantation. This structured set of recommendations guides the prioritization of minimum requirements to establish a transplantation program and set the stage for expansion and further development.

Infection Rates among Acute Leukemia Patients Receiving Alternative Donor Hematopoietic Cell Transplantation.

Alternative graft sources (umbilical cord blood [UCB], matched unrelated donors [MUD], or mismatched unrelated donors [MMUD]) enable patients without a matched sibling donor to receive potentially curative hematopoietic cell transplantation (HCT). Retrospective studies demonstrate comparable outcomes among different graft sources. However, the risk and types of infections have not been compared among graft sources. Such information may influence the choice of a particular graft source. We compared the incidence of bacterial, viral, and fungal infections in 1781 adults with acute leukemia who received alternative donor HCT (UCB, n= 568; MUD, n = 930; MMUD, n = 283) between 2008 and 2011. The incidences of bacterial infection at 1 year were 72%, 59%, and 65% (P < .0001) for UCB, MUD, and MMUD, respectively. Incidences of viral infection at 1 year were 68%, 45%, and 53% (P < .0001) for UCB, MUD, and MMUD, respectively. In multivariable analysis, bacterial, fungal, and viral infections were more common after either UCB or MMUD than after MUD (P < .0001). Bacterial and viral but not fungal infections were more common after UCB than MMUD (P = .0009 and <.0001, respectively). The presence of viral infection was not associated with an increased mortality. Overall survival (OS) was comparable among UCB and MMUD patients with Karnofsky performance status (KPS) ≥ 90% but was inferior for UCB for patients with KPS < 90%. Bacterial and fungal infections were associated with poorer OS. Future strategies focusing on infection prevention and treatment are indicated to improve HCT outcomes.

Effect of cord blood processing on transplantation outcomes after single myeloablative umbilical cord blood transplantation.

Variations in cord blood manufacturing and administration are common, and the optimal practice is not known. We compared processing and banking practices at 16 public cord blood banks (CBB) in the United States and assessed transplantation outcomes on 530 single umbilical cord blood (UCB) myeloablative transplantations for hematologic malignancies facilitated by these banks. UCB banking practices were separated into 3 mutually exclusive groups based on whether processing was automated or manual, units were plasma and red blood cell reduced, or buffy coat production method or plasma reduced. Compared with the automated processing system for units, the day 28 neutrophil recovery was significantly lower after transplantation of units that were manually processed and plasma reduced (red cell replete) (odds ratio, .19; P = .001) or plasma and red cell reduced (odds ratio, .54; P = .05). Day 100 survival did not differ by CBB. However, day 100 survival was better with units that were thawed with the dextran-albumin wash method compared with the "no wash" or "dilution only" techniques (odds ratio, 1.82; P = .04). In conclusion, CBB processing has no significant effect on early (day 100) survival despite differences in kinetics of neutrophil recovery.

Increasing incidence of chronic graft-versus-host disease in allogeneic transplantation: a report from the Center for International Blood and Marrow Transplant Research.

Although transplant practices have changed over the last decades, no information is available on trends in incidence and outcome of chronic graft-versus-host disease (cGVHD) over time. This study used the central database of the Center for International Blood and Marrow Transplant Research (CIBMTR) to describe time trends for cGVHD incidence, nonrelapse mortality, and risk factors for cGVHD. The 12-year period was divided into 3 intervals, 1995 to 1999, 2000 to 2003, and 2004 to 2007, and included 26,563 patients with acute leukemia, chronic myeloid leukemia, and myelodysplastic syndrome. Multivariate analysis showed an increased incidence of cGVHD in more recent years (odds ratio = 1.19, P < .0001), and this trend was still seen when adjusting for donor type, graft type, or conditioning intensity. In patients with cGVHD, nonrelapse mortality has decreased over time, but at 5 years there were no significant differences among different time periods. Risk factors for cGVHD were in line with previous studies. This is the first comprehensive characterization of the trends in cGVHD incidence and underscores the mounting need for addressing this major late complication of transplantation in future research.

Early failure of frontline rituximab-containing chemo-immunotherapy in diffuse large B cell lymphoma does not predict futility of autologous hematopoietic cell transplantation.

The poor prognosis for patients with diffuse large B cell lymphoma (DLBCL) who relapse within 1 year of initial diagnosis after first-line rituximab-based chemo-immunotherapy has created controversy about the role of autologous transplantation (HCT) in this setting. We compared autologous HCT outcomes for chemosensitive DLBCL patients between 2000 and 2011 in 2 cohorts based on time to relapse from diagnosis. The early rituximab failure (ERF) cohort consisted of patients with primary refractory disease or those with first relapse within 1 year of initial diagnosis. The ERF cohort was compared with those relapsing >1 year after initial diagnosis (late rituximab failure [LRF] cohort). ERF and LRF cohorts included 300 and 216 patients, respectively. Nonrelapse mortality (NRM), progression/relapse, progression-free survival (PFS), and overall survival (OS) of ERF versus LRF cohorts at 3 years were 9% (95% confidence interval [CI], 6% to 13%) versus 9% (95% CI, 5% to 13%), 47% (95% CI, 41% to 52%) versus 39% (95% CI, 33% to 46%), 44% (95% CI, 38% to 50%) versus 52% (95% CI, 45% to 59%), and 50% (95% CI, 44% to 56%) versus 67% (95% CI, 60% to 74%), respectively. On multivariate analysis, ERF was not associated with higher NRM (relative risk [RR], 1.31; P = .34). The ERF cohort had a higher risk of treatment failure (progression/relapse or death) (RR, 2.08; P < .001) and overall mortality (RR, 3.75; P <.001) within the first 9 months after autologous HCT. Beyond this period, PFS and OS were not significantly different between the ERF and LRF cohorts. Autologous HCT provides durable disease control to a sizeable subset of DLBCL despite ERF (3-year PFS, 44%) and remains the standard-of-care in chemosensitive DLBCL regardless of the timing of disease relapse.

Low CD34 dose is associated with poor survival after reduced-intensity conditioning allogeneic transplantation for acute myeloid leukemia and myelodysplastic syndrome.

Reduced-intensity conditioning/nonmyeloablative conditioning regimens are increasingly used in allogeneic hematopoietic cell transplantation (HCT). Reports have shown CD34(+) dose to be important for transplantation outcome using myeloablative conditioning. The role of CD34(+) dose of peripheral blood progenitor cells (PBPC) has not been previously analyzed in a large population undergoing reduced-intensity conditioning/nonmyeloablative HCT. We studied 1054 patients, ages 45 to 75 years, with acute myeloid leukemia or myelodysplastic syndrome who underwent transplantation between 2002 and 2011. Results of multivariate analysis showed that PBPC from HLA-matched siblings containing <4 × 10(6) CD34(+)/kg was associated with higher nonrelapse mortality (hazard ratio [HR], 2.03; P = .001), overall mortality (HR, 1.48; P = .008), and lower neutrophil (odds ratio [OR], .76; P = .03) and platelet (OR, .76; P = .03) recovery. PBPC from unrelated donors with CD34(+) dose < 6 × 10(6) CD34(+)/kg was also associated with higher nonrelapse (HR, 1.38; P = .02) and overall mortality (HR, 1.20; P = .05). In contrast to reports after myeloablative HCT, CD34(+) dose did not affect relapse or graft-versus-host disease with either donor type. An upper cell dose limit was not associated with adverse outcomes. These data suggest that PBPC CD34(+) doses >4 × 10(6) CD34(+)/kg and >6 × 10(6) CD34(+)/kg are optimal for HLA-matched sibling and unrelated donor HCT, respectively.

Does total body irradiation conditioning improve outcomes of myeloablative human leukocyte antigen-identical sibling transplantations for chronic lymphocytic leukemia?

An allogeneic hematopoietic cell transplantation from an HLA-identical donor after high-dose (myeloablative) pretransplantation conditioning is an effective therapy for some people with chronic lymphocytic leukemia (CLL). Because CLL is a highly radiosensitive cancer, we hypothesized that total body irradiation (TBI) conditioning regimens may be associated with better outcomes than those without TBI. To answer this, we analyzed data from 180 subjects with CLL receiving myeloablative doses of TBI (n = 126) or not (n = 54), who received transplants from an HLA-identical sibling donor between 1995 and 2007 and reported to the Center for International Blood & Marrow Transplant Research. At 5 years, treatment-related mortality was 48% (95% confidence interval [CI], 39% to 57%) versus 50% (95% CI, 36% to 64%); P = NS. Relapse rates were 17% (95% CI, 11% to 25%) versus 22% (95% CI, 11% to 35%); P = NS. Five-year progression-free survival and overall survival were 34% (95% CI, 26% to 43%) versus 28% (95% CI, 15% to 42%); P = NS and 42% (95% CI, 33% to 51%) versus 33% (95% CI, 19% to 48%); P = NS, respectively. The single most common cause of death in both cohorts was recurrent/progressive CLL. No variable tested in the multivariate analysis was found to significantly affect these outcomes, including having failed fludarabine. Within the limitations of this study, we found no difference in HLA-identical sibling transplantation outcomes between myeloablative TBI and chemotherapy pretransplantation conditioning in persons with CLL.

Effect of postremission therapy before reduced-intensity conditioning allogeneic transplantation for acute myeloid leukemia in first complete remission.

The impact of pretransplant (hematopoietic cell transplantation [HCT]) cytarabine consolidation therapy on post-HCT outcomes has yet to be evaluated after reduced-intensity or nonmyeloablative conditioning. We analyzed 604 adults with acute myeloid leukemia in first complete remission (CR1) reported to the Center for International Blood and Marrow Transplant Research who received a reduced-intensity or nonmyeloablative conditioning HCT from an HLA-identical sibling, HLA-matched unrelated donor, or umbilical cord blood donor from 2000 to 2010. We compared transplant outcomes based on exposure to cytarabine postremission consolidation. Three-year survival rates were 36% (95% confidence interval [CI], 29% to 43%) in the no consolidation arm and 42% (95% CI, 37% to 47%) in the cytarabine consolidation arm (P = .16). Disease-free survival was 34% (95% CI, 27% to 41%) and 41% (95% CI, 35% to 46%; P = .15), respectively. Three-year cumulative incidences of relapse were 37% (95% CI, 30% to 44%) and 38% (95% CI, 33% to 43%), respectively (P = .80). Multivariate regression confirmed no effect of consolidation on relapse, disease-free survival, and survival. Before reduced-intensity or nonmyeloablative conditioning HCT, these data suggest pre-HCT consolidation cytarabine does not significantly alter outcomes and support prompt transition to transplant as soon as morphologic CR1 is attained. If HCT is delayed while identifying a donor, our data suggest that consolidation does not increase transplant treatment-related mortality and is reasonable if required.

Complement fragment 3a priming of umbilical cord blood progenitors: safety profile.

Preclinical data showed that priming CD34(+) hematopoietic progenitor cells with complement fragment 3a (C3a) improved homing and engraftment. Thus, we hypothesized that priming of umbilical cord blood (UCB) hematopoietic progenitors with C3a would facilitate homing and could potentially be used to address the need for improved engraftment after UCB transplantation. We primed 1 of 2 UCB units for double UCB transplantation after nonmyeloablative conditioning. This design provided adequate safety and the potential to observe skewed long-term chimerism in favor of the C3a-primed unit as a surrogate measure of efficacy. C3a priming of 1 UCB unit did not result in infusional toxicity. Increased grades 1 to 3 hypertension were the only infusional adverse events observed in 9 (30%) patients. We observed no activation of inflammatory or coagulation pathways downstream of C3a. As tested, C3a priming did not impair engraftment, but did not skew chimerism toward the treated unit. As compared with historical controls, mortality and survival were not adversely affected. Thus, before any additional clinical studies, C3a priming to promote engraftment will require further preclinical optimization.

Who is the better donor for older hematopoietic transplant recipients: an older-aged sibling or a young, matched unrelated volunteer?

Older patients are increasingly undergoing allogeneic hematopoietic transplantation. A relevant question is whether outcomes can be improved with a younger allele-level 8/8 HLA-matched unrelated donor (MUD) rather than an older HLA-matched sibling (MSD). Accordingly, transplants in leukemia/lymphoma patients age ≥50 years were analyzed comparing outcomes for recipients of MSD ≥50 (n = 1415) versus MUD <50 years (n = 757). Risks of acute graft-versus-host disease (GVHD) grade 2 to 4 (hazard ratio [HR], 1.63; P < .001), 3 to 4 (HR, 1.85; P < .001), and chronic GVHD (HR, 1.48; P < .0001) were higher after MUD compared with MSD transplants. The effect of donor type on nonrelapse mortality (NRM), relapse, and overall mortality was associated with performance score. For patients with scores of 90 or 100, NRM (HR, 1.42; P = .001), relapse (HR, 1.45; P < .001), and overall mortality (HR, 1.28; P = .001) risks were higher after MUD transplants. For patients with scores below 90, NRM (HR, 0.96; P = .76), relapse (HR, 0.86; P = .25), and overall mortality (HR, 0.90; P = .29) were not significantly different after MUD and MSD transplants. These data favor an MSD over a MUD in patients age ≥50 years.

Double unit grafts successfully extend the application of umbilical cord blood transplantation in adults with acute leukemia.

UNLABELLED: Cell dose is a major limitation for umbilical cord blood (UCB) transplantation because units containing a minimum of 2.5 x 10(7) total nucleated cells (TNC)/kilogram patient body weight are frequently not available. The transplantation of 2 partially HLA-matched UCB units has been adopted as a simple approach for increasing the TNC.We sought to determine whether the relative safety and efficacy of this approach was comparable with a single UCB transplantation. Included are adults with acute leukemia who received transplants with 1 (n =106) or 2 (n =303) UCB units. All UCB units for single UCB transplantations contained TNC ≥ 2.5 x 10(7)/kg. For double UCB transplantations, the total TNC for units 1 and 2 were > 2.5 x 10(7)/kg but in approximately half of these transplantations, 1 of the 2 units contained < 2.5 x 10(7) TNC/kg. Adjusting for factors associated with outcomes, risks of neutrophil recovery (odds ratio 0.83, P =.59), transplantation-related mortality (hazard ratio [HR] 0.91, P= .63), relapse (HR 0.90, P= .64), and overall mortality (HR 0.93, P= .62) was similar after double UCB and adequate dose single UCB transplantations. These data support double UCB unit transplantation for acute leukemia when an adequately dosed single UCB unit is not available thereby extending access to nearly all patients. KEY POINTS: Efficacy of transplanting adequately dosed 1- or 2-cord blood units.

Reduced-intensity conditioning transplantation in acute leukemia: the effect of source of unrelated donor stem cells on outcomes.

We report the relative efficacy of co-infusing 2 umbilical cord blood units (dUCB) compared with peripheral blood progenitor cells (PBPCs) from 8 of 8 or 7 of 8 HLA-matched unrelated donors. All patients received reduced-intensity conditioning (RIC) regimens. Four treatment groups were evaluated: 4-6 of 6 matched dUCB-TCF (n = 120; TCF = total body irradiation [TBI] 200 cGy + cyclophosphamide + fludarabine), 4-6 of 6 matched dUCB-other (n = 40; alkylating agent + fludarabine ± TBI), and 8 of 8 (n = 313) and 7 of 8 HLA-matched PBPCs (n = 111). Compared with matched 8 of 8 PBPC transplantations, transplantation-related mortality (TRM), and overall mortality were similar after dUCB-TCF (relative risk [RR] 0.72, P = .72; RR 0.93, P = .60) but higher after dUCB-other RIC (hazard ratio [HR] 2.70, P = .0001; 1.79 P = .004). Compared with 7 of 8 PBPC transplantations, TRM (but not overall mortality) was lower after dUCB-TCF (RR 0.57, P = .04; RR 0.87 P = .41). The probabilities of survival after dUCB-TCF, dUCB-other RIC, and 8 of 8 PBPC and 7 of 8 PBPC transplantations were 38%, 19%, 44%, and 37%, respectively. With similar survival after 8 of 8, 7 of 8 matched PBPCs, and dUCB-TCF, these data support use of dUCB-TCF transplantation in adults with acute leukemia who may benefit from RIC transplantation urgently or lack a 7-8 of 8 unrelated donor.

Effect of donor-recipient HLA matching at HLA A, B, C, and DRB1 on outcomes after umbilical-cord blood transplantation for leukaemia and myelodysplastic syndrome: a retrospective analysis.

BACKGROUND: The importance of matching at the HLA C locus has not been well defined for unrelated umbilical-cord blood transplantation. The selection algorithm for umbilical-cord blood units generally considers intermediate resolution HLA typing at A and B and allele-level typing at DRB1. We aimed to establish the relative importance of additional matching at HLA C. METHODS: We used Cox regression to assess retrospectively the effect of donor-recipient HLA matching on outcomes of single umbilical-cord blood transplantations for leukaemia and myelodysplastic syndrome. Our primary endpoint was transplant-related mortality. HLA typing was done with molecular techniques with a minimum of intermediate resolution for HLA A, B, and C, and at the allele-level for DRB1. FINDINGS: The median age of our study population was 10 years (range <1-62) and 552 (69%) of 803 patients were aged 16 years or younger at transplantation. Compared with transplantations matched at HLA A, B, C, and DRB1 (n=69), transplant-related mortality risk was higher after transplantations matched at HLA A, B, and DRB1 and mismatched at HLA C (n=23; HR 3·97, 95% CI 1·27-12·40; p=0·018). Transplant-related mortality risk was also higher after transplantations with a single mismatch at HLA A, B, or DRB1 and mismatched at HLA C (n=234; 1·70, 1·06-2·74; p=0·029) compared with transplantations matched at HLA C with a single mismatch at HLA A, B, or DRB1 (n=127). Assessing the overall effect of HLA disparity on transplant-related mortality, risks were higher with units mismatched at two (n=259; 3·27, 1·42-7·54; p=0·006), three (n=253; 3·34, 1·45-7·71; p=0·005), or four (n=75; 3·51, 1·44-8·58; p=0·006) loci compared with matched units (n=69). INTERPRETATION: Our data suggest that the present strategy for umbilical-cord blood unit selection should be reassessed; matching at HLA C for units that are matched at HLA A, B, or DRB1 or in the presence of a single locus mismatch at HLA A, B, or DRB1 should be included to minimise mortality risks. FUNDING: National Cancer Institute, National Heart Lung and Blood Institute, National Institute for Allergy and Infectious Diseases, Leukemia and Lymphoma Society, US Department of the Navy, Children's Leukemia Research Association, and INSERM.

Donor characteristics affecting graft failure, graft-versus-host disease, and survival after unrelated donor transplantation with reduced-intensity conditioning for hematologic malignancies.

We examined the effect of donor characteristics on graft failure (<5% donor chimerism within 3 months after transplantation), acute and chronic graft-versus-host disease (aGVHD, cGVHD), and survival after unrelated donor reduced-intensity conditioning (RIC) transplantation in 709 patients with hematologic malignancies. Donor-recipient pairs were HLA typed at HLA-A, -B, -C, and -DRB1 (allele-level). A total of 501 patients were >95% donor chimerism, 145 patients were 5% to 95%, and 63 patients were <5%. The only donor characteristic associated with transplantation outcome was donor-recipient HLA matching. One- or 2-loci mismatched transplants led to higher grade 2-4 (relative risk [RR] = 1.27, P = .035) and grade 3-4 (RR = 1.85, P < .001) aGVHD and 2-loci mismatched transplants higher mortality (RR = 2.22, P < .001). Graft failure was higher after transplantation of bone marrow (RR = 2.33, P = .002). Donor age, parity, and donor sex match were not associated with transplantation outcome. Donor-recipient HLA matching is the only donor characteristic predictive for survival after RIC regimens for hematologic malignancies.

Spontaneous autologous graft-versus-host disease in plasma cell myeloma autograft recipients: flow cytometric analysis of hematopoietic progenitor cell grafts.

Nine plasma cell myeloma patients spontaneously developed histologically proven autologous graft-versus-host disease (GVHD) limited predominantly to the gastrointestinal tract within 1 month of initial autologous hematopoietic cell transplantation (AHCT) using high-dose melphalan conditioning. All recipients responded promptly to systemic and nonabsorbable oral corticosteroid therapy. All patients previously received systemic therapy with thalidomide, lenalidomide, or bortezomib before AHCT. Using enzymatic amplification staining-enhanced flow cytometry, we evaluated expression of selected transcription regulators, pathway molecules, and surface receptors on samples of the infused hematopoietic cell grafts. We demonstrated significantly enhanced expression of GATA-2, CD130, and CXCR4 on CD34(+) hematopoietic progenitor cells of affected patients compared with 42 unaffected AHCT controls. These 3 overexpressed markers have not been previously implicated in autologous GVHD. Although we did not specifically evaluate T cells, we postulate that exposure over time to the various immunomodulating therapies used for induction treatment affected not only the CD34(+) cells but also T cells or relevant T cell subpopulations capable of mediating GVHD. After infusion, the affected hematopoietic progenitor cells then encounter a host that has been further altered by the high-dose melphalan preparative regimen; such a situation leads to the syndrome. These surface markers could be used to develop a model to predict development of this syndrome. Autologous GVHD potentially is a serious complication of AHCT and should be considered in plasma cell myeloma patients with otherwise unexplained gastrointestinal symptoms in the immediate post-AHCT period. Prompt recognition of this condition and protracted treatment with nonabsorbable or systemic corticosteroids or the combination may lead to resolution.

Safety and efficacy of bone marrow-derived autologous CD133+ stem cell therapy.

The Phase I clinical study was designed to assess the safety and feasibility of a dose escalating intracoronary infusion of autologous bone marrow (BM)-derived CD133+ stem cell therapy to the patients with chronic total occlusion (CTO) and ischemia. Nine patients were received CD133+ cells into epicardial vessels supplying collateral flow to areas of viable ischemic myocardium in the distribution of the CTO. There were no major adverse cardiac events (MACE), revascularization, re-admission to the hospital secondary to angina, or acute myocardial infarction (AMI) for the 24-month period following cellular infusion. In addition, there were no periprocedural infusion-related complications including malignant arrhythmias, loss of normal coronary blood flow or acute neurologic events. Cardiac enzymes were negative in all patients. There was an improvement in the degree of ischemic myocardium, which was accompanied by a trend towards reduction in anginal symptoms. Intracoronary infusion of autologous CD133+ marrow-derived cells is safe and feasible. Cellular therapy with CD133+ cells to reduce anginal symptoms and to improve ischemia in patients with CTO awaits clinical investigation in Phase II/III trials.

Strategies to enhance umbilical cord blood stem cell engraftment in adult patients.

Umbilical cord blood (UCB) has been used successfully as a source of hematopoietic stem cells (HSCs) for allogeneic transplantation in children and adults in the treatment of hematologic diseases. However, compared with marrow or mobilized peripheral blood stem cell grafts from adult donors, significant delays in the rates and kinetics of neutrophil and platelet engraftment are noted after UCB transplant. These differences relate in part to the reduced numbers of HSCs in UCB grafts. To improve the rates and kinetics of engraftment of UCB HSC, several strategies have been proposed, including ex vivo expansion of UCB HSCs, addition of third-party mesenchymal cells, intrabone delivery of HSCs, modulation of CD26 expression, and infusion of two UCB grafts. This article will focus on ex vivo expansion of UCB HSCs and strategies to enhance UCB homing as potential solutions to overcome the problem of low stem cell numbers in a UCB graft.

Umbilical cord blood stem cells for myocardial repair and regeneration.

Cardiovascular disease remains a major cause of morbidity and mortality with substantial economic cost. There remains a need for therapeutic improvement for patients refractory to revascularization and those who redevelop occlusions following revascularization. Early evidence linked age-associated reductions in the levels of circulating marrow-derived hematopoietic stem cells (HSC), characterized by expression of early HSC markers CD133 and CD34, with the occurrence of cardiovascular events and associated death. Heart tissue has the endogenous ability to regenerate through the activation of resident cardiac stem cells or through recruitment of a stem cell population from other tissues, such as bone marrow. A number of clinical trials have utilized patient-derived autologous bone marrow-derived cells or whole BM uncultured mononuclear cells (MNC) infused or injected locally to augment angiogenesis. In most cases of treating animal models with human cells, the frequency of stem cell engraftment, the subsequent number of newly generated cardiomyocytes and vascular cells, and the augmentation of endogenous microvascular collateralization, either by deposition, transdifferentiation, and/or by cell fusion, appear to be too low to explain the significant cardiac improvement. Initially, it was hypothesized that cell therapy may work by cell replacement mechanisms, but recent evidence suggests alternatively that cell therapy works by providing trophic support to the injured tissues. An alternative hypothesis is that the transplanted stem cells release soluble cytokines and growth factors (i.e., paracrine factors) that function in a paracrine fashion, contributing to cardiac repair and regeneration by inducing cytoprotection and neovascularization. Another hypothesis which may also be operative is that cell therapy may mediate endogenous regeneration by the activation of resident cardiac stem cell. Well-established clinical trials have used cord blood for the treatment of hematological malignances (e.g., leukemia, lymphoma, myeloma) and nonmalignancies (e.g., in born errors of metabolism, sickle cells anemia, autoimmune diseases), but further advances in other areas of regenerative medicine (e.g., cardiac repair) will directly benefit with the use of cord blood. These clinical outcomes demonstrate that effector cells may be delivered by an allogeneic approach, where strict tissue matching may not be necessary and treatment may be achieved by making use of the trophic support capability of cell therapy and not by a cell replacement mechanism.