Hematopoietic cell transplantation: five decades of progress

Cellular Therapies: Yesterday, Today, and Tomorrow

Cellular therapy (CT) can be defined as the transference into a person of healthy cells to correct defective functions. Yesterday (1950-2010), CT consisted mostly of hematopoietic transplants for the treatment of a variety of hematological disorders. Interestingly, during that period of time other cell types with therapeutic potential-including certain lymphoid populations and other nonhematopoietic cells-were discovered and characterized; thus, CT became a promising discipline for the treatment of a broader diversity of diseases. Today (2011-2023), CT has significantly grownup through preclinical studies and clinical trials, and it is currently progressing toward its consolidation as one of the pillars of medicine in the 21st century. Indeed, different types of stem cells (e.g., hematopoietic, mesenchymal, neural, and pluripotent), as well as different lymphoid and myeloid cell populations (e.g., TILs, CAR-Ts, CAR-NKs, and DUOC-01) are being used in clinical settings or are being tested in clinical trials. For the past decade, several CT modalities have been developed, and today, many of them are being used in the clinic. Tomorrow (2024-2040), already established CT modalities will surely be improved and applied more frequently, and novel therapies (that will include cell types such as iPSCs) will enter and expand within the clinical ground. It is noteworthy, however, that despite significant advancements and achievements, problems still need to be solved and obstacles need to be overcome. Technical, ethical, and economic issues persist and they need to be addressed. Undoubtedly, exciting times of challenges and opportunities are coming ahead in the CT arena.

Establishment of Chimerism and Organ Transplant Tolerance in Laboratory Animals: Safety and Efficacy of Adaptation to Humans

The definition of immune tolerance to allogeneic tissue and organ transplants in laboratory animals and humans continues to be the acceptance of the donor graft, rejection of third-party grafts, and specific unresponsiveness of recipient immune cells to the donor alloantigens in the absence of immunosuppressive treatments. Actively acquired tolerance was achieved in mice more than 60 years ago by the establishment of mixed chimerism in neonatal mice. Once established, mixed chimerism was self-perpetuating and allowed for acceptance of tissue transplants in adults. Successful establishment of tolerance in humans has now been reported in several clinical trials based on the development of chimerism after combined transplantation of hematopoietic cells and an organ from the same donor. This review examines the mechanisms of organ graft acceptance after establishment of mixed chimerism (allo-tolerance) or complete chimerism (self-tolerance), and compares the development of graft versus host disease (GVHD) and graft versus tumor (GVT) activity in complete and mixed chimerism. GVHD, GVT activity, and complete chimerism are also discussed in the context of bone marrow transplantation to treat hematologic malignancies. The roles of transient versus persistent mixed chimerism in the induction and maintenance of tolerance and organ graft acceptance in animal models and clinical studies are compared. Key differences in the stability of mixed chimeras and tolerance induction in MHC matched and mismatched rodents, large laboratory animals, and humans are examined to provide insights into the safety and efficacy of translation of results of animal models to clinical trials.

Gene Therapy of the Hemoglobinopathies

Sickle cell disease and the ß-thalassemias are caused by mutations of the ß-globin gene and represent the most frequent single gene disorders worldwide. Even in European countries with a previous low frequency of these conditions the prevalence has substantially increased following large scale migration from Africa and the Middle East to Europe. The hemoglobin diseases severely limit both, life expectancy and quality of life and require either life-long supportive therapy if cure cannot be achieved by allogeneic stem cell transplantation. Strategies for ex vivo gene therapy aiming at either re-establishing normal ß-globin chain synthesis or at re-activating fetal γ-globin chain and HbF expression are currently in clinical development. The European Medicine Agency (EMA) conditionally licensed gene addition therapy based on lentiviral transduction of hematopoietic stem cells in 2019 for a selected group of patients with transfusion dependent non-ß° thalassemia major without a suitable stem cell donor. Gene therapy thus offers a relevant chance to this group of patients for whom cure has previously not been on the horizon. In this review, we discuss the potential and the challenges of gene addition and gene editing strategies for the hemoglobin diseases.

Periodontal disease might be a risk factor for graft versus host disease. A systematic review

PURPOSE

The aim of this systematic review was to determine a potential association between periodontal disease and graft versus host disease (GVHD).

DESIGN

PubMed, Scopus and Web of Science databases were searched to identify all relevant articles. The eligibility criteria were prospective, retrospective, cross-sectional, cohort, case-control studies and interventional studies that assessed periodontal parameters in GVHD adults' patients.

RESULTS

Seven studies, published between 2000 and 2018, were eligible. The aggravation of periodontal tissues is due to inadequate oral hygiene, dental plaque, decays, gum recession, retained roots, tooth loss, periodontally infected teeth. Several studies have indicated that periodontitis treatment performed before transplantation showed the reduction of gingival inflammation and maintenance of periodontal health.

CONCLUSIONS

Periodontitis might be a risk factor for GVHD. However, due to the limited number of studies included in the review and their heterogeneity, more data are needed to sustain the correlation between periodontitis and GVHD.

Topical Cyclosporine Pretreatment of Ocular Surface in Allogeneic Hematopoietic Stem Cell Transplant Recipients

PURPOSE

Dry eye disease (DED) of ocular graft-versus-host disease (GVHD) is a common complication after allogeneic hematopoietic stem cell transplantation (HSCT). Ongoing inflammation and irreversible fibrotic changes of the ocular surface and adnexa are obstacles for effective treatment of ocular GVHD. We hypothesized that topical cyclosporine A (CsA) pretreatment might be effective in preventing ocular GVHD.

METHODS

In this prospective, randomized, comparative study, patients were randomly assigned to the topical CsA treatment (4 times daily in both eyes for a month before allogeneic HSCT and continued use of eye drops after transplantation) or control (no treatment) groups. Participants underwent thorough ophthalmic examination-including Ocular Surface Disease Index questionnaire survey, Schirmer test, tear break-up time (TBUT) evaluation, and corneal fluorescein staining-before and 1, 2, and 3 months after allogeneic HSCT.

RESULTS

Fifty-eight participants completed the study. Among patients with baseline Schirmer values <10 mm and TBUT <5 s before allogenic HSCT, those in the topical CsA treatment group exhibited significantly better corresponding values after transplantation than patients in the control group.

CONCLUSIONS

Topical CsA pretreatment might be beneficial in the early stage of DED and might prevent further inflammation and consequent irreversible fibrosis, especially in patients with preexisting DED components.

Thirteen novel canine dog leukocyte antigen-88 alleles identified by sequence-based typing

Major histocompatibility complex (MHC) genes in mammals include highly polymorphic class I and class II genes that are critical for donor-recipient matching for transplantation. Dogs have served as an effective, directly translatable model for stem/progenitor cell transplantation. Previous analyses of MHC class I genes in dogs point to a single highly polymorphic gene, dog leukocyte antigen (DLA)-88, as an important factor in the success or failure of hematopoietic stem cell transplants. Fifty-nine DLA-88 alleles have been identified and reported so far. Here, we extend this list by presenting 13 novel DLA-88 alleles found in domestic dogs.

First Successful Haploidentical Stem Cell Transplantation in Romania

Hematopoietic stem cell transplantation is an established treatment for many malignant and non-malignant haematological disorders. In the current case report, we describe the first haploidentical stem cell transplantation, used for the first time in Romania, the case of a 33 year-old young woman diagnosed with Hodgkin's lymphoma that has underwent a haploSCT after she relapsed from several chemotherapy regimens, as well as after an autologous stem cell transplantation. This success represents a prèmiere in Romanian clinical hematology, being the first case of a haploSCT in Romania, as well as in South-Eastern Europe.

MicroRNAs as biomarkers for graft-versus-host disease following allogeneic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HCT) is a well-established treatment for many malignant and non-malignant hematological disorders. As frequent complication in up to 50 % of all patients, graft-versus-host disease (GVHD) is still the main cause for morbidity and non-relapse mortality. Diagnosis of GVHD is usually done clinically, even though confirmation by pathology is often used to support the clinical findings. Effective treatment requires intensified immunosuppression as early as possible. Although several promising biomarkers have been proposed for an early diagnosis, no internationally recognized consensus has yet been established. Here, microRNAs (miRs) represent an interesting tool since miRs have been recently reported to be an important regulator of various cells, including immune cells such as T cells. Therefore, we could assume that miRs play a key role in the pathogenesis of acute GVHD, and their detection might be an interesting possibility in the early diagnosis and monitoring of acute GVHD. Recent studies additionally demonstrated the implication of miRs in the pathogenesis of acute GVHD. In this review, we aim to summarize the previous reports of miRs, focusing on the pathogenesis of acute GVHD and possible implications in diagnostic approaches.

Hematopoietic stem cells: an overview

Considerable efforts have been made in recent years in understanding the mechanisms that govern hematopoietic stem cell (HSC) origin, development, differentiation, self-renewal, aging, trafficking, plasticity and transdifferentiation. Hematopoiesis occurs in sequential waves in distinct anatomical locations during development and these shifts in location are accompanied by changes in the functional status of the stem cells and reflect the changing needs of the developing organism. HSCs make a choice of either self-renewal or committing to differentiation. The balance between self-renewal and differentiation is considered to be critical to the maintenance of stem cell numbers. It is still under debate if HSC can rejuvenate infinitely or if they do not possess ''true" self-renewal and undergo replicative senescence such as any other somatic cell. Gene therapy applications that target HSCs offer a great potential for the treatment of hematologic and immunologic diseases. However, the clinical success has been limited by many factors. This review is intended to summarize the recent advances made in the human HSC field, and will review the hematopoietic stem cell from definition through development to clinical applications.

Preservation of stem cells

Adult stem cells (hematopoietic and mesenchymal) have demonstrated tremendous human therapeutic potential. Currently, human embryonic stem cells are used principally for understanding development and disease progression but also hold tremendous therapeutic potential. The ability to preserve stem cells is critical for their use in clinical and research applications. Preservation of cells permits the transportation of cells between sites, as well as completion of safety and quality control testing. Preservation also permits the development of a 'manufacturing paradigm' for cell therapies, thereby maximizing the number of products that can be produced at a given facility. in this article, we will review modes of preservation and the current status of preservation of hematopoietic, mesenchymal and human embryonic stem cells. Current and emerging issues in the area of stem cell preservation will also be described.

Stem cell therapies for muscle disorders

PURPOSE OF REVIEW

This review focuses on stem cell-based therapies to treat skeletal muscle disorders, with a special emphasis on muscular dystrophies.

RECENT FINDINGS

We briefly review previous attempts at cell therapy by the use of donor myoblasts, explaining the likely reasons for the poor clinical results; we then describe the use of the same cells in current promising trials for localized treatments of different diseases of skeletal muscle. Moreover, we discuss important novel findings on muscle stem/progenitor cell biology and their promise for future clinical translation. Preclinical and clinical applications of novel myogenic stem/progenitor cells are also described.

SUMMARY

We summarize several ongoing clinical trials for different muscle disorders and the advances in the understanding of the biology of the myogenic progenitors used in such trials. On the basis of the currently available information, a prediction of developments in the field is proposed.

Umbilical cord blood: lessons learned and lingering challenges after more than 20 years of basic and clinical research

During the last 23 years, cord blood research has played important roles both in experimental and clinical hematology. Cord blood-derived hematopoietic stem and progenitor cells have been shown to possess particular biological features and their study has been very important in our understanding of hematopoietic development. Today, >20,000 umbilical cord blood (UCB) transplants have been performed worldwide and ∼460,000 UCB units are being stored in >47 UCB banks worldwide. Here a brief overview on some of the most relevant issues regarding cord blood research is presented.

Rabbit antithymocyte globulin (thymoglobulin): 25 years and new frontiers in solid organ transplantation and haematology

The more than 25 years of clinical experience with rabbit antithymocyte globulin (rATG), specifically Thymoglobulin, has transformed immunosuppression in solid organ transplantation and haematology. The utility of rATG has evolved from the treatment of allograft rejection and graft-versus-host disease to the prevention of various complications that limit the success of solid organ and stem cell transplantation. Today, rATG is being successfully incorporated into novel therapeutic regimens that seek to reduce overall toxicity and improve long-term outcomes. Clinical trials have demonstrated the efficacy and safety of rATG in recipients of various types of solid organ allografts, recipients of allogeneic stem cell transplants who are conditioned with both conventional and nonconventional regimens, and patients with aplastic anaemia. Over time, clinicians have learnt how to better balance the benefits and risks associated with rATG. Advances in the understanding of the multifaceted mechanism of action will guide research into new therapeutic areas and future applications.

A limited sampling schedule to estimate individual pharmacokinetic parameters of fludarabine in hematopoietic cell transplant patients

PURPOSE

Fludarabine monophosphate (fludarabine) is frequently administered to patients receiving a reduced-intensity conditioning regimen for allogeneic hematopoietic cell transplant (HCT) in an ambulatory care setting. These patients experience significant interpatient variability in clinical outcomes, potentially due to pharmacokinetic variability in 2-fluoroadenine (F-ara-A) plasma concentrations. To test such hypotheses, patient compliance with the blood sampling should be optimized by the development of a minimally intrusive limited sampling schedule (LSS) to characterize F-ara-A pharmacokinetics. To this end, we sought to create the first F-ara-A population pharmacokinetic model and subsequently a LSS.

EXPERIMENTAL DESIGN

A retrospective evaluation of F-ara-A pharmacokinetics was conducted after one or more doses of daily i.v. fludarabine in 42 adult HCT recipients. NONMEM software was used to estimate the population pharmacokinetic parameters and compute the area under the concentration-time curve.

RESULTS

A two-compartment model best fits the data. A LSS was constructed using a simulation approach, seeking to minimize the scaled mean squared error for the area under the concentration-time curve for each simulated individual. The LSS times chosen were 0.583, 1.5, 6.5, and 24 hours after the start of the 30-minute fludarabine infusion.

DISCUSSION

The pharmacokinetics of F-ara-A in an individual HCT patient can be accurately estimated by obtaining four blood samples (using the LSS) and maximum a posteriori Bayesian estimation.

CONCLUSION

These are essential tools for prospective pharmacodynamic studies seeking to determine if clinical outcomes are related to F-ara-A pharmacokinetics in patients receiving i.v. fludarabine in the ambulatory clinic.

DC homeostasis in hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation is an important experimental tool and therapeutic modality. Its efficacy and toxicity are both linked to a GvH reaction that is initiated by donor T cells recognizing recipient APC, of which DC are the most potent. In most tissues recipient DC are replaced after transplantation because they turnover rapidly from BM-derived precursors. However, in a number of sites, notably the skin, recipient DC may persist and even self-renew for many months after transplantation. Understanding the homeostasis of different APC populations and how they are related to the induction of alloreactivity may help to improve the therapeutic benefit of transplantation.

Exploring the Clinical Characteristics of Parenteral Nutrition Recipients Admitted for Initial Hematopoietic Stem Cell Transplantation

There is a paucity of evidence to guide the initiation of parenteral nutrition administration during hematopoietic stem cell transplantation. The purpose of this study was to explore and compare clinical characteristics during early hematopoietic stem cell transplantation to discern if differences existed between those that had parenteral nutrition initiated and those that did not. Medical records of patients admitted for initial autologous or allogeneic hematopoietic stem cell transplantation from two university transplantation centers were evaluated for this retrospective cohort. A multitude of clinical features were evaluated at baseline and in the days preceding parenteral nutrition initiation to investigate potential differences between parenteral nutrition and non-parenteral nutrition subjects, stratified by donor type. To examine the occurrence of events prior to parenteral nutrition administration, a "before" time frame was created for all subjects. For parenteral nutrition subjects, the actual number of hospital days prior to parenteral nutrition initiation was used; however, for non-parenteral nutrition patients, the transplantation-specific average number of days until parenteral nutrition initiation, depicted as "before" (ie, autologous non-parenteral nutrition "before"=hospital days 1 to 10, allogeneic non-parenteral nutrition "before"=hospital days 1 to 13), was used during this parallel timeframe. Differences were assessed using Student's t and Wilcoxon rank sum tests for continuous variables, and chi(2) for categorical variables. Parenteral nutrition was provided to 53% (n=129/245) of autologous and 65% (n=73/112) of allogeneic patients and was typically initiated on transplant day +6 and day +7, respectively. Significant decreases in oral intake patterns (P<0.0001) and a tendency toward infections were observed for autologous (P=0.01) and allogeneic (P=0.07) parenteral nutrition vs non-parenteral nutrition recipients "before." In addition, significantly more mucositis was observed "before" in allogeneic parenteral nutrition vs non-parenteral nutrition patients (P=0.04). Involvement of nutrition professionals is crucial for the design and implementation of future studies to determine for whom and when to commence parenteral nutrition and to discourage its indiscriminant use.

Dendritic cell homeostasis and trafficking in transplantation

Hematopoietic cell transplantation and solid organ transplantation are definitive therapies for several otherwise fatal conditions. Post-transplant immune reactions are the major cause of morbidity after transplantation and limit the extended use of these critical therapies. Post-transplant immune complications include graft rejection by the host and injury to the host mediated by the graft. Dendritic cells (DCs), a population of professional antigen-presenting cells, are thought to be crucial in triggering primary immune responses against both the graft and the host. Here, we review studies on DC homeostasis and trafficking after transplantation, and examine the role of the host and graft DC in post-transplant immune responses. We also discuss the therapeutic implications of these studies.

Growth kinetics of progenitor cell-enriched hematopoietic cell populations in long-term liquid cultures under continuous removal of mature cells

BACKGROUND

During long-term culture of primitive hematopoietic cells large numbers of mature cells are generated that, on the one hand, consume nutrients and cytokines present in the medium and, on the other hand, may produce or elicit the production of soluble factors that limit the growth of primitive cells. Thus it is possible that under standard culture conditions hematopoietic stem and progenitor cells are unable to display their true proliferation and expansion potentials.

METHODS

Hematopoietic cell populations, enriched for CD34+ cells, were obtained from both umbilical cord blood (UCB) and mobilized peripheral blood (MPB), and cultured in cytokine-supplemented liquid culture, under continuous removal of mature cells by means of weekly re-selection of primitive, lineage-negative (Lin-) cells. Proliferation and expansion capacities of such cells were determined weekly for a 42-day culture period.

RESULTS

As expected, based on our previous studies in standard liquid cultures, throughout the culture period there was a continuous decrease in the proportion of progenitor cells; however, after every re-selection on days 7, 14 and 21, there was a significant enrichment for both CD34+ cells and colony-forming cells (CFC). As a result of such an enrichment, the cumulative increase in the numbers of total cells and CFC in cultures with two, three or four selections was significantly higher than the increments observed in standard cultures, in which only a single selection was performed on day 0. Cultures of UCB cells showed consistently higher levels of both total cells and CFC than cultures of MPB cells.

DISCUSSION

Taken together, these results indicate that continuous removal of mature cells from liquid cultures of primitive progenitors results in higher increments in the levels of both total cells and CFC.

Graft-vs-host disease: nutrition therapy in a challenging condition

Graft-vs-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation. Both acute and chronic forms of GVHD are challenging to manage medically and nutritionally. Patients with advanced GVHD commonly become depleted nutritionally, with loss of lean body mass (LBM) and functional status. We present 2 case reports of patients who developed GVHD and subsequent nutrition decline. Although both patients were candidates for specialized nutrition support (SNS), only 1 was able to receive enteral and parenteral nutrition due to GVHD complications preventing access for provision of SNS. Fortunately, the patients have remained in remission from their hematologic malignancy, but they continue to cope with chronic GVHD and its consequences. These cases exhibit the complexity of managing a patient with extensive GVHD and nutrition interventions for clinicians to consider to optimize outcomes.

Glycogen synthase kinase-3 is an in vivo regulator of hematopoietic stem cell repopulation

The in vivo regulation of hematopoietic stem cell (HSC) function is poorly understood. Here, we show that hematopoietic repopulation can be augmented by administration of a glycogen synthase kinase-3 (GSK-3) inhibitor to recipient mice transplanted with mouse or human HSCs. GSK-3 inhibitor treatment improved neutrophil and megakaryocyte recovery, recipient survival and resulted in enhanced sustained long-term repopulation. The output of primitive Lin(-)c-Kit(+)Sca-1(+) cells and progenitors from HSCs increased upon GSK-3 inhibitor treatment without altering secondary repopulating ability, suggesting that the HSC pool is maintained while overall hematopoietic reconstitution is increased. GSK-3 inhibitors were found to modulate gene targets of Wnt, Hedgehog and Notch pathways in cells comprising the primitive hematopoietic compartment without affecting mature cells. Our study establishes GSK-3 as a specific in vivo modulator of HSC activity, and suggests that administration of GSK-3 inhibitors may provide a clinical means to directly enhance the repopulating capacity of transplanted HSCs.

Dendritic cells in allogeneic hematopoietic stem cell transplantation

In allogeneic hematopoietic stem cell transplantation (SCT), dendritic cells (DCs) as the most potent antigen-presenting cells play a central role in the development of acute and chronic graft-vs-host disease (GVHD), in graft-vs-leukemia or -malignancy reactions and in fighting infectious complications. Functional maturity and distribution of DC sub-types (DC1 and DC2) differ between the different stem cell sources used (bone marrow, granulocyte colony-stimulating factor-mobilised peripheral blood and cord blood) resulting in various rates of graft-vs-host disease and graft-vs-leukemia activity. Although DC recovery following stem cell transplantation is prompt, graft-vs-host disease and the use of immunosuppressive drugs result in qualitative and quantitative disturbances in DC homeostasis and have been observed for up to 1 year after transplantation. Complete donor DC chimerism seems to be a pre-requisite for the development of chronic GVHD and for graft-vs-leukemia activity, at least following reduced-intensity transplants, although in the early phase of acute graft-vs-host disease the presence of host antigen-presenting cells is essential. Preliminary data show promising results with DC-based immunotherapy for treatment of viral and fungal infections and of leukemic relapse following allogeneic stem cell transplantation. More information on the mechanisms and interactions between dendritic cells and regulatory T cells is needed for DC vaccination concepts for modulation of graft-vs-host disease.

Haematopoietic stem cell transplantation to treat aplastic anaemia

Aplastic anaemia (AA) consists of pancytopenia and empty bone marrow. Its incidence varies worldwide but predominates in developing countries. Diverse aetiologies are involved, with autoimmunity at the centre of the picture. For the 70% of patients with the severe and very severe forms of AA and who lack a human leukocyte antigen (HLA)-matched sibling, immunosuppressive therapy (IST) is key in treating the disease, with a remission rate close to 70%, an 80-90% 5-year survival rate in responding patients and a relapse rate close to 10%. For the 30% with a sibling donor available, haematopoietic stem cell transplant (HSCT) from bone marrow or peripheral blood has up to a 90% chance of cure, with a 5-10% graft rejection/failure rate. Patients who fail IST (25-30%) and lack a sibling donor can benefit from CD34(+)-enriched, partially T cell-depleted unrelated stem cell transplants, with a general survival rate up to 37%, the newest source of stem cells for this modality being cord blood. Non-myeloablative, irradiation-free conditioning regimens offer appreciable benefits, and new immunosuppressive agents, such as fludarabine and alemtuzumab, have been incorporated with promising preliminary results. Graft-versus-host disease, graft failure and infections remain significant challenges in HSCT for which innovative treatment strategies are being developed at present.

Human embryonic stem cells and chromosome stability

The use of human embryonic stem cells (HESC) in research is increasing exponentially and HESC will certainly be of importance in biological, clinical and toxicological research for many years to come. Once established, HESC lines are expected to be chromosomally stable. However, our own experience of culturing HESC and some published reports indicate that HESC may show chromosomal instability while being cultured continuously in vitro. We conclude that the effects of different culture techniques and long-term culture on the chromosome stability of HESC still remain to be elucidated and we recommend regular analysis of the chromosome constitution in cell lines using traditional karyotyping, CGH, FISH and PCR. We also recommend freezing of HESC at low passage number and in larger batches after thawing and expansion in order to secure material in case mutations occur in the cell line at a later stage of culture.

Cause of death after allogeneic haematopoietic stem cell transplantation (HSCT) in early leukaemias: an EBMT analysis of lethal infectious complications and changes over calendar time

We analysed a large homogeneous group of 14,403 patients transplanted for early leukaemia from an HLA-identical sibling and reported to the EBMT in four time cohorts: 1980-1989 (24%), 1990-1994 (26%), 1995-1998 (30%) and 1999-2001 (20%). We focused on death from infection. End points were survival, death from relapse and transplant-related mortality (TRM), which was subdivided into death from graft-versus-host disease (GvHD) (1315 patients; 25% of deaths), infection (597 patients; 11% of deaths) or 'other' causes (1875 patients; 34% of deaths). Survival increased from 52% at 5 years in the first to 62% in the third cohort (P<0.05) and TRM decreased from 36 to 26% (P<0.05) due to a reduction in death from infection (P<0.001). GvHD, 'other' causes and relapse did not improve. The relative proportions of bacteria (217 patients; 36%), viruses (183 patients; 31%), fungi (166 patients; 28%) or parasites (32 patients; 5%) as cause of infectious death (cumulative incidence of death at 5 years 1.8, 1.6, 1.4 and > or = 0.3%, respectively) and median time to death from infections (3 months (range 0-158 months)) did not change. Death from infections has been reduced significantly, but it still represents an ongoing risk after HSCT and draws attention to the time beyond the initial period of neutropenia.

Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplantation (HSCT) requires the harvest of an adequate number of stem cells (SC) from a histocompatible donor and their infusion into a patient following a conditioning regimen. During the past 35 years, the role of HSCT has changed from an experimental procedure for terminally ill patients to a curative treatment. In 2003, 1170 procedures were registered in Italy (Italian Group for Blood and Marrow Transplantation). The main reported indications were as follows: leukemia, lymphoproliferative diseases, myelodysplasia, and nonmalignant diseases such as thalassemia and severe aplastic anemia. Important changes have been observed in the last 5 years: the shift from bone marrow to peripheral blood as the SC source, the increasing number of alternative donors such as unrelated, partially matched family donors and cord blood SC, and the new extra-hematological indications including solid tumors. Moreover, the development of nonmyeloablative conditioning regimens have allowed physicians to perform HSCT in patients with advanced age or important comorbidities. In contrast, the availability of the Tyrosine kinase inhibitor (STI-571) for treatment of patients affected by chronic myelogenous leukemia, which was formerly the main indication for HSCT, has produced a dramatic decrease in the number of transplantations in this setting. HSCT performed in the early phases of disease and in young patients offers more than a 50% cure rate. The transplant-related mortality still represents the greatest obstacle, ranging from 20%-30%, despite the less toxic conditioning regimens, high-resolution HLA typing, and better supportive care. GvHD and infections remain the main causes of morbidity. As regards relapses, they correlate with disease status at the time of transplantation. Promising results have been recently obtained with haploidentical and with cord blood SC transplantation also in adult patients.

Kinetics of engraftment following allogeneic hematopoietic cell transplantation with reduced-intensity or nonmyeloablative conditioning

Nonmyeloablative or reduced-intensity conditioning regimens have been used to condition elderly or ill patients with hematological malignancies for allogeneic hematopoietic cell transplantation (HCT). Initial mixed donor/host chimerism (i.e. the coexistence of hematopoietic cells of host and donor origin) has been observed in most patients after such transplants. Here, we describe both factors affecting engraftment kinetics in patients given a nonmyeloablative or a reduced-intensity conditioning, and associations between peripheral blood cell subset chimerism levels and HCT outcomes.

Evidence-based guidelines for the management of neutropenia following outpatient hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) involves the transfer of stem cells to establish hematopoiesis in patients who have received myeloablative chemotherapy with or without whole body irradiation. Following high-dose therapy and HSCT, all patients experience a period of neutropenia. Outpatient care delivery models place expanded responsibilities on patients and their families for the management of this treatment side effect. Proactive management of neutropenia is critical to decrease the depth and duration of neutropenia following HSCT, limit exposure to opportunistic and nosocomial pathogens, and ensure prompt intervention should febrile neutropenia or infection develop. Patient and family education, psychosocial support, and coordination of care are key nursing responsibilities.

Allogeneic hematopoietic cell transplantation: from experimental biology to clinical care

PURPOSE

For more than half a century, researchers have explored myeloablative, high-dose chemo/radiotherapy followed by allogeneic hematopoietic stem cell transplantation (HCT) for therapy of malignant and nonmalignant hematological diseases. Continuous advances in the field have changed this approach from one that was initially thought to be fraught by insurmountable complications to one that is now considered standard therapy for many diseases.

METHODS

In order to extend allogeneic HCT to include elderly patients, who represent the main population affected by hematological malignancies, and to those who are medically unfit to undergo conventional HCT, novel non-myeloablative approaches have been developed. These approaches rely on graft-vs-tumor effects for tumor eradication rather than high-dose chemoradiotherapy, and, accordingly, have lower toxicities than conventional regimens.

RESULTS

Results with non-myeloablative regimens have been gratifying, and this may change the future of allogeneic HCT. Advances could not have been possible without basic research and studies in pre-clinical animal models.

CONCLUSION

Further work is focused on improving graft-vs-tumor effects while achieving better control of graft-vs-host disease.