Hematopoietic and immune recovery after allogeneic peripheral blood stem cell transplantation and bone marrow transplantation in a pediatric population

Bone marrow harvest in donors with anaemia

BACKGROUND

Bone marrow harvest (BMH) for haematopoietic stem cell transplantation is a well-established procedure. The guidelines of World Marrow Donor Association provide information on donor selection. However, some of the guidelines regarding donors with anaemia prior to harvest lack in supporting data from clinical studies. With this study, we aimed to provide such data.

MATERIAL AND METHODS

In this retrospective, single-centre study, we analysed the interplay between haemoglobin levels and BMH and BMH impact on haemoglobin levels in a cohort of 149 unrelated BM donors, including 13 subjects with mild anaemia.

RESULTS

The BMH led to significantly lower decrease in haemoglobin levels in donors with anaemia than in control group (1·79 g/dl vs. 2·56 g/dl, P < 0·0001). The following parameters: BMH volume (ml), BMH volume/donor body weight (ml/kg), total nucleated cells (TNC) in product (×10⁸ ) and TNC/kg recipient body weight in product (×10⁸ /kg) did not differ significantly between those two analysed groups (P > 0·05). Median BM volume harvested from anaemic donors was 16·34 ml/kg; none of them required blood transfusion after BMH.

CONCLUSION

Mild anaemia prior to BMH does not significantly impact the collection results. The BMH is safe and feasible in donors with mild anaemia.

In Vivo Evaluation of Pharmacologically Active Microcarriers Releasing Nerve Growth Factor and Conveying PC12 Cells

Cell therapy will probably become a major therapeutic strategy in the coming years. Nevertheless, few cells survive transplantation when employed as a treatment for neuronal disorders. To address this problem, we have developed a new tool, the pharmacologically active microcarriers (PAM). PAM are biocompatible and biodegradable microparticles coated with cell adhesion molecules, conveying cells on their surface and presenting a controlled delivery of growth factor. Thus, the combined effect of growth factor and coating influences the transported cells by promoting their survival and differentiation and favoring their integration in the host tissue after their complete degradation. Furthermore, the released factor may also influence the microenvironment. In this study, we evaluated their efficacy using nerve growth factor (NGF)-releasing PAM and PC12 cells, in a Parkinson's disease paradigm. After implantation of NGF-releasing or unloaded PAM conveying PC12 cells, or PC12 cells alone, we studied cell survival, differentiation, and apoptosis, as well as behavior of the treated rats. We observed that the NGF-releasing PAM coated with two synthetic peptides (poly-D-lysine and fibronectin-like) induced PC12 cell differentiation and reduced cell death and proliferation. Moreover, the animals receiving this implant presented an improved amphetamine-induced rotational behavior. These findings indicate that PAM could be a promising strategy for cell therapy of neurological diseases and could be employed in other situations with fetal cell transplants or with stem cells.

Reconstitution rate of absolute CD8+ T lymphocyte counts affects overall survival after pediatric allogeneic hematopoietic stem cell transplantation

Immune reconstitution after allogeneic stem cell transplantation protects against opportunistic infections and disease relapse. Identifying the most protective lymphocyte subset would have implications of adoptive immunotherapy. We followed up a case series of 34 allogeneic transplantations for pediatric leukemias, aplastic anemias, or solid tumors. Regardless of baseline hematologic disorder, the speed of reconstitution of cytotoxic CD8 T lymphocytes and the achieving of the 10th percentile of normal CD4 T lymphocytes (but not B lymphocytes or natural killer cells) conditioned overall survival. The source of hematopoietic stem cells (peripheral blood vs bone marrow) and the occurrence of graft-versus-host disease (either acute or chronic) did not impact on immune reconstitution. Larger case series are needed to confirm the pivotal role of cytotoxic CD8 T lymphocytes in overall survival.

Pharmacologically active microcarriers: a tool for cell therapy

To overcome certain problems encountered in cell therapy, particularly cell survival, lack of cell differentiation and integration in the host tissue, we developed pharmacologically active microcarriers (PAM). These biodegradable particles made with poly(D,L-lactic-co-glycolic acid) (PLGA) and coated with adhesion molecules may serve as a support for cell culture and may be used as cell carriers presenting a controlled delivery of active protein. They can thus support the survival and differentiation of the transported cells as well as their microenvironment. To develop this tool, nerve growth factor (NGF)-releasing PAM, conveying PC12 cells, were produced and characterized. Indeed, these cells have the ability to differentiate into sympathetic-like neurons after adhering to a substrate, in the presence of NGF, and can then release large amounts of dopamine. Certain parameters such as the size of the microcarriers, the conditions enabling the coating of the microparticles and the subsequent adhesion of cells were thus studied to produce optimized PAM.

Lymphocyte recovery as a positive predictor of prolonged survival after autologous peripheral blood stem cell transplantation in T-cell non-Hodgkin's lymphoma

We performed a retrospective study on recovery and survival of patients with T-cell NHL after autologous peripheral blood stem cell transplantation (APBSCT). Of a total of 39 patients with high-risk T-cell NHL, 33 were analyzed. Six patients who experienced early treatment mortality without full lymphocyte recovery were excluded. We chose absolute lymphocyte count (ALC) recovery as 1000 cells/microl as a cutoff value. ALC recovery day was defined as the first of 3 consecutive days with ALC above 1000 cells/microl. Univariate analysis revealed that age younger than 45 years, good international prognostic index, chemosensitive disease prior to APBSCT, and early ALC recovery (1000 cells/microl within 25 days of APBSCT) were predictors of prolonged survival. Multivariate analyses confirmed that chemosensitive disease prior to APBSCT and early ALC recovery were strongly associated with better overall survival (OS) (P=0.005 and 0.011, respectively) and progression-free survival (PFS) (P<0.001 and P=0.013, respectively). Our finding, that ALC recovery > or =1000 cells/microl is an independent predictor of OS and PFS in T-cell NHL after APBSCT, suggests that earlier immune recovery may contribute to longer survival.

Primed marrow for autologous and allogeneic transplantation: A review comparing primed marrow to mobilized blood and steady-state marrow

Mobilized peripheral blood collections, obtained following either chemotherapy (with or without granulocyte colony-stimulating factor (G-CSF)) or G-CSF administration alone, are rapidly replacing traditional bone marrow harvests as the source of cells for hematopoietic stem cell transplantation. According to the Autologous Blood and Marrow Transplant and the International Bone Marrow Transplant Registries, for the years 1998 through 2000, blood stem cell (BSC) transplants accounted for about 80% of autologous transplants in the pediatric age group and more than 90% of the autologous transplants among adults. In allogeneic transplantation, where the donor is a healthy family member or normal volunteer, G-CSF-mobilized BSC transplants are being used more and more frequently, accounting for about 20% of allogeneic transplants in the pediatric age range and more than 40% of allogeneic transplants among adults during the same time period. It is not, therefore, too great a stretch to imagine that BSC transplants will soon be, if not already, in the majority for allogeneic transplantation among adults. The principal reason why this is happening is the prevailing view that BSC engraft more rapidly than marrow stem cells (MSC). However, this view is based on comparisons between primed circulating blood cells (BSC) and unprimed resident marrow cells in the steady state (SS-MSC). If the reason why BSC engraft faster than SS-MSC were a consequence of G-CSF used for mobilization, then would priming of MSC by G-CSF (Prim-MSC) accelerate engraftment of marrow as well? We reviewed the literature of the last 10 years to see if there were enough data to answer this question.