Haematopoietic stem cell transplantation: current concepts and novel therapeutic strategies

Umbilical cord blood derived cell expansion: a potential neuroprotective therapy

Umbilical cord blood (UCB) is a rich source of beneficial stem and progenitor cells with known angiogenic, neuroregenerative and immune-modulatory properties. Preclinical studies have highlighted the benefit of UCB for a broad range of conditions including haematological conditions, metabolic disorders and neurological conditions, however clinical translation of UCB therapies is lacking. One barrier for clinical translation is inadequate cell numbers in some samples meaning that often a therapeutic dose cannot be achieved. This is particularly important when treating adults or when administering repeat doses of cells. To overcome this, UCB cell expansion is being explored to increase cell numbers. The current focus of UCB cell expansion is CD34+ haematopoietic stem cells (HSCs) for which the main application is treatment of haematological conditions. Currently there are 36 registered clinical trials that are examining the efficacy of expanded UCB cells with 31 of these being for haematological malignancies. Early data from these trials suggest that expanded UCB cells are a safe and feasible treatment option and show greater engraftment potential than unexpanded UCB. Outside of the haematology research space, expanded UCB has been trialled as a therapy in only two preclinical studies, one for spinal cord injury and one for hind limb ischemia. Proteomic analysis of expanded UCB cells in these studies showed that the cells were neuroprotective, anti-inflammatory and angiogenic. These findings are also supported by in vitro studies where expanded UCB CD34+ cells showed increased gene expression of neurotrophic and angiogenic factors compared to unexpanded CD34+ cells. Preclinical evidence demonstrates that unexpanded CD34+ cells are a promising therapy for neurological conditions where they have been shown to improve multiple indices of injury in rodent models of stroke, Parkinson's disease and neonatal hypoxic ischemic brain injury. This review will highlight the current application of expanded UCB derived HSCs in transplant medicine, and also explore the potential use of expanded HSCs as a therapy for neurological conditions. It is proposed that expanded UCB derived CD34+ cells are an appropriate cellular therapy for a range of neurological conditions in children and adults.

Inflammatory Biomarkers for Outcome Prediction in Patients With Metastatic Testicular Cancer

Germ cell tumors are the most common malignant tumors in male young adults. Platinum-based chemotherapy has dramatically improved the outcome of metastatic germ cell tumor patients and overall cure rates now exceed 80%. The choice of medical treatment can be guided by the prognosis estimation which is an important step during the decision-making process. IGCCCG classification plays a pivotal role in the management of advanced disease. However, histological and clinical parameters are the available factors that condition the prognosis, but they do not reflect the tumor's molecular and pathological features and do not predict who will respond to chemotherapy. After first-line chemotherapy 20%-30% of patients relapse and for these patients, the issue of prognostic factors is far more complex. Validated biomarkers and a molecular selection of patients that reflect the pathogenesis are highly needed. The association between cancer-related systemic inflammation, tumorigenesis, and cancer progression has been demonstrated. In the last years, several studies have shown the prognostic utility of immune-inflammation indexes in different tumor types. This review analyzed the prognostic impact of inflammatory markers retrieved from routine blood draws in GCT patients.

Approaches of stem cell mobilization in a large cohort of metastatic germ cell cancer patients

High-dose chemotherapy (HD-Cx) in refractory germ cell cancer (GCC) is effective but limited data are available concerning the optimal approach for stem cell mobilization (SCM) in these patients. In this analysis 102 patients undergoing SCM during first (n = 25) or subsequent treatment lines (n = 77) were analyzed. Subcutaneous injections of granulocyte colony-stimulating factor (G-CSF) were given once daily (group 1) in 52 patients (51%), twice daily (group 2) in 39 patients (38%) or one injection Pegylated-G-CSF (PegG-CSF) (group 3) in eleven patients (11%) after one cycle of mobilization chemotherapy. Plerixafor was administered 13 times in group 1, seven times in group 2 and once in group 3. Overall, 77 (75%) patients achieved successful SCM defined as ≥8*10⁶ CD34+ cells/kg body weight for three consecutive HD-Cx plus one backup dose. In group 1, 40 of 52 patients (77%) achieved successful SCM with a median of 11 G-CSF injections, in group 2, 27 of 39 patients (69%) with a median of 14 G-CSF injections and in group 3, 10 of 11 patients (91%) with one injection of PegG-CSF. SCM was more successful if conducted during first-line chemotherapy (p = 0.016) and associated with a beneficial outcome concerning overall survival (p = 0.02) if performed satisfactorily.

Whole-body Vibration Training as a Supportive Therapy During Allogeneic Haematopoietic Stem Cell Transplantation – A Randomised Controlled Trial

Effects of whole-body vibration (WBV) training in patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) remain unknown. We examined whether additional WBV training during hospitalisation may stabilise the physical capacity of patients undergoing allogeneic HSCT, improve health-related quality of life (HRQOL) and fatigue status of these patients. In this randomised controlled trial, 26 subjects were randomly allocated 1:1 in an intervention group (INT; n=13) or a control group (CON; n=13). Patients in the CON received conventional physical therapy and patients in the INT completed further WBV training every other day. Isokinetic measurement of the muscular capacity of the lower extremities, functional endurance capacity and HRQOL were evaluated before and after the intervention period. No unwanted side effects were observed. We found a significant positive effect of the intervention on the maximum relative peak torque in extension in the INT compared to the CON (p=0.019) and patients in the INT experienced less pain (p=0.05). WBV training can be successfully implemented as a supportive therapy for patients undergoing allogeneic HSCT. Furthermore, WBV training represents a safe and effective option in the maintenance of muscular capacity of the musculature of the lower extremities and may contribute to pain release.

Manufacture of GMP-compliant functional adenovirus-specific T-cell therapy for treatment of post-transplant infectious complications

BACKGROUND AIMS

In pediatric patients, adenovirus (ADV) reactivation after allogeneic hematopoietic stem cell transplantation (allo HSCT) is a major cause of morbidity and mortality. For patients who do not respond to antiviral drug therapy, a new treatment approach using ADV-specific T cells can present a promising alternative. Here we describe the clinical scale Good Manufacturing Practice (GMP)-compliant manufacture and characterization of 40 ADV-specific T-cell products, Cytovir ADV, which are currently being tested in a multi-center phase I/IIa clinical trial. This process requires minimal intervention, is high yield, and results in a pure T-cell product that is functional.

METHODS

Mononuclear cells (2 × 10(7)) were cultured in a closed system in the presence of GMP-grade ADV peptide pool and cytokines for 10 days. On day 10, the T-cell product was harvested, washed in a closed system, counted and assessed for purity and potency. Additional characterization was carried out where cell numbers allowed.

RESULTS

Thirty-eight of 40 products (95%) met all release criteria. Median purity of the cell product was 88.3% CD3+ cells with a median yield of 2.9 × 10(7) CD3+ cells. Potency analyses showed a median ADV-specific interferon (IFN)γ response of 5.9% of CD3+ and 2345 IFNγ spot-forming cells/million. CD4 and CD8 T cells were capable of proliferating in response to ADV (63.3 and 56.3%, respectively). These virus-specific T cells (VST) were heterogenous, containing both effector memory and central memory T cells. In an exemplar patient with ADV viremia treated in the open ASPIRE trial, ADV-specific T-cell response was detected by IFNγ enzyme-linked immunospot from 13 days post-infusion. ADV DNA levels declined following cellular therapy and were below level of detection from day 64 post-infusion onward.

CONCLUSIONS

The clinical-scale GMP-compliant One Touch manufacturing system is feasible and yields functional ADV-specific T cells at clinically relevant doses.

Optimizing mobilization strategies in difficult-to-mobilize patients: The role of plerixafor

Peripheral blood stem cell collection is currently the most widely used source for hematopoietic autologous transplantation. Several factors such as advanced age, previous chemotherapy, disease and marrow infiltration at the time of mobilization influence the efficacy of CD34(+) progenitor cell mobilization. Despite the safety and efficiency of the standard mobilization protocols (G-CSF ± chemotherapy), there is still a significant amount of mobilization failure rate (10-40%), which necessitate novel agents for effective mobilization. Plerixafor, is a novel agent, has been recently approved for mobilization of hematopoietic stem cells (HSCs). The combination of Plerixafor with G-CSF provides the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail with standard mobilization regimens. The development and optimization of practical algorithms for the use Plerixafor is crucial to make hematopoietic stem cell mobilization more efficient in a cost-effective way. This review is aimed at summarizing how to identify poor mobilizers, and define rational use of Plerixafor for planning mobilization in hard-to-mobilize patients.

Peripheral blood stem cell transplantation in a significant body weight difference between a smaller donor and a larger recipient: a case report

Allogeneic peripheral blood stem cell transplantation (PBSCT) is becoming a common transplantation procedure in children. However, few benefits have been reported, in particular in regard to the choice of small children as donors for larger recipients. We report a case of relapsed acute myeloid leukemia (body weight 52 kg and blood type O) who underwent allogeneic PBSCT from his smaller human leukocyte antigen-matched brother (body weight 29.9 kg and blood type A).

Adrenaline administration promotes the efficiency of granulocyte colony stimulating factor-mediated hematopoietic stem and progenitor cell mobilization in mice

A high dose of granulocyte colony stimulating factor (G-CSF) is widely used to mobilize hematopoietic stem and progenitor cells (HSPC), but G-CSF is relatively inefficient and may cause adverse effects. Recently, adrenaline has been found to play important roles in HSPC mobilization. In this study, we explored whether adrenaline combined with G-CSF could induce HSPC mobilization in a mouse model. Mice were treated with adrenaline and either a high or low dose of G-CSF alone or in combination. Peripheral blood HSPC counts were evaluated by flow cytometry. Levels of bone marrow SDF-1 were measured by ELISA, the transcription of CXCR4 and SDF-1 was measured by real-time RT-PCR, and CXCR4 protein was detected by Western blot. Our results showed that adrenaline alone fails to mobilize HSPCs into the peripheral blood; however, when G-CSF and adrenaline are combined, the WBC counts and percentages of HSPCs are significantly higher compared to those in mice that received G-CSF alone. The combined use of adrenaline and G-CSF not only accelerated HSPC mobilization, but also enabled the efficient mobilization of HSPCs into the peripheral blood at lower doses of G-CSF. Adrenaline/G-CSF treatment also extensively downregulated levels of SDF-1 and CXCR4 in mouse bone marrow. These results demonstrated that adrenaline combined with G-CSF can induce HSPC mobilization by down-regulating the CXCR4/SDF-1 axis, indicating that the use of adrenaline may enable the use of reduced dosages or durations of G-CSF treatment, minimizing G-CSF-associated complications.

European data on stem cell mobilization with plerixafor in patients with nonhematologic diseases: an analysis of the European consortium of stem cell mobilization

BACKGROUND

Plerixafor with granulocyte-colony-stimulating factor (G-CSF) has been shown to enhance stem cell mobilization in patients with multiple myeloma and lymphoma with previous mobilization failure. In this European named patient program we report the experience in insufficiently mobilizing patients diagnosed with nonhematologic diseases.

STUDY DESIGN AND METHODS

Thirty-three patients with germ cell tumor (n=11), Ewing sarcoma (n=6), Wiscott-Aldrich disease (n=5), neuroblastoma (n=4), and other nonhematologic diseases (n=7) were included in the study. Plerixafor was limited to patients with previous or current stem cell mobilization failure and given after 4 days of G-CSF (n=21) or after chemotherapy and G-CSF (n=12) in patients who mobilized poorly.

RESULTS

Overall, 28 (85%) patients succeeded in collecting at least 2×10(6)/kg body weight (b.w.) CD34+ cells (median, 5.0×10(6)/kg b.w. CD34+ cells; range, 2.0×10(6)-29.5×10(6)/kg b.w. CD34+ cells), and five (15%) patients collected a median of 1.5×10(6)/kg b.w. CD34+ cells (range, 0.9×10(6)-1.8×10(6)/kg b.w. CD34+ cells). Nineteen patients proceeded to transplantation. The median dose of CD34+ cells infused was 3.3×10(6)/kg b.w. (range, 2.3×10(6)-6.7×10(6)/kg b.w. CD34+ cells). The median numbers of days to neutrophil and platelet engraftment were 11 (range, 9-12) and 15 (range, 10-25) days, respectively.

CONCLUSION

These data emphasize the role of plerixafor in combination with G-CSF or chemotherapy and G-CSF as an effective mobilization regimen with the potential of successful stem cell collection. Accordingly, plerixafor seems to be safe and effective in patients with nonhematologic diseases. Larger prospective studies are warranted to further assess its use in these patients.

Neurological disorders and the potential role for stem cells as a therapy

Introduction Neurological disorders are routinely characterized by loss of cells in response to an injury or a progressive insult. Stem cells could therefore be useful to treat these disorders. Sources of data Pubmed searches of recent literature. Areas of agreement Stem cells exhibit proliferative capacity making them ideally suited for replacing dying cells. However, instead of cell replacement therapy stem cell transplants frequently appear to work via neurotrophic factor release, immunomodulation and upregulation of endogenous stem cells. Areas of controversy and areas timely for developing research Many questions remain with respect to the use of stem cells as a therapy, the answers to which will vary depending on the disorder to be treated and mode of action. Whereas the potential tumorigenic capability of stem cells is a concern, most studies do not support this notion. Further determination of the optimal cell type, and whether to perform allogeneic or autologous transplants warrant investigation before the full potential of stem cells can be realized. In addition, the use of stem cells to develop disease models should not be overlooked.

Plerixafor is effective and safe for stem cell mobilization in heavily pretreated germ cell tumor patients

Up to 10% of germ cell tumor patients require salvage high-dose chemotherapy with stem cell support, achieving cure rates in the range of 10-60%. Stem cell mobilization may be difficult in these patients because of multiple lines of treatment known to seriously hamper stem cell recovery. Plerixafor significantly enhances the success of the CD34+ cell harvest, even in cases where prior mobilization attempts have failed. Six germ cell tumor patients provided informed consent and were included in the compassionate use program. All patients were heavily pretreated, with a median of 3.5 prior lines of therapy. All failed prior mobilization with G-CSF in combination with chemotherapy. Five patients yielded a median of 2.6 × 10(6) CD34+ cells per kg body weight in a median of 4 apheresis days when plerixafor was used. Three patients underwent subsequent high-dose chemotherapy with autologous stem cell support. Median time to leukocyte engraftment was 11 days. Median time to platelet engraftment was 12.5 days, both of which are comparable to previous historical data. Accordingly, plerixafor seems to be safe and effective in germ cell tumor patients who have failed prior mobilization therapy. Larger prospective studies are warranted to further assess its use in germ cell cancer.

Vagrant stem cells draft their gene companions

In a recent issue of Nature Medicine, Ryan et al. (2010) uncover genetic modifiers of G-CSF responses by hematopoietic progenitors. The authors document a negative role of EGFR signaling and, provided an analogous pathway functions in humans, propose a potential new angle to promote clinical blood stem cell mobilization.

Immune regulatory cells in umbilical cord blood and their potential roles in transplantation tolerance

Umbilical cord blood (UCB) is a source of primitive hematopoietic stem (HSC) and progenitor cells, that served as an alternative to bone marrow (BM) for effective transplantation therapy. Success of HSC transplantation (HSCT) is limited in part by graft-versus-host disease (GVHD), graft rejection and delayed immune reconstitution, which all relate to immunological complications. GVHD after UCB transplantation is lower compared to that of BM HSCT. This may relate to the tolerogenic nature of T cells, mononuclear cells (MNCs) and especially immune regulatory cells existing in UCB. UCB contains limiting numbers of HSC or CD34(+) cell dose for adult patients resulting in delayed engraftment after UCB transplantation (UCBT). This needs to be improved for optimal transplantation outcomes. Approaches have been undertaken to promote HSC engraftment, including co-infusion of multiple units of UCB cells. These new methods however added additional immunological complications. Herein, we describe current knowledge on features of UCB immune cells, including regulatory T cells (Tregs) and mesenchymal stem/stromal cells (MSCs) and their potential future usage to reduce GVHD.