Peripheral Progenitor Cells Research Articles

Allogeneic hematopoietic cell transplantation for adult metachromatic leukodystrophy: a case series

AbstractMetachromatic leukodystrophy (MLD) is a rare genetic disorder caused by pathogenic variants of the ARSA gene, leading to a deficiency of the arylsulfatase A enzyme (ARSA) and consecutive accumulation of galactosylceramide-3-0-sulfate in the nervous system. The condition leads to severe neurological deficits and subsequently results in profound intellectual and motoric disability. Especially, the adult form of MLD, which occurs in individuals aged >16 years, poses significant challenges for treating physicians because of the rarity of cases, limited therapeutic options, and different allogeneic hematopoietic cell transplantation (allo-HCT) protocols worldwide. Here, we report the results of allo-HCT treatment in 4 patients with a confirmed adult MLD diagnosis. Bone marrow or mobilized peripheral progenitor cells were infused after a reduced intensity conditioning regime consisting of fludarabine and treosulfan. In 3 patients, allo-HCT was followed by an infusion of mesenchymal cells to further consolidate ARSA production. We observed a good tolerability and an increase in ARSA levels up to normal range values in all patients. A full donor chimerism was detected in 3 patients within the first 12 months. In a 1-year follow-up, patients with complete donor chimerism showed a neurological stable condition. Only 1 patient with an increasing autologous chimerism showed neurological deterioration and a decline in ARSA levels in the first year. In summary, allo-HCT offers a therapeutic option for reconstituting ARSA enzyme levels in adult patients with MLD, with tolerable side effects.

Influence of the Me2SO removal on key parameters of cryopreserved autologous peripheral progenitor cells concentrates: a retrospective study in patients with primary or secondary amyloidosis

Influence of the Me2SO removal on key parameters of cryopreserved autologous peripheral progenitor cells concentrates: a retrospective study in patients with primary or secondary amyloidosis

The Effect of Cryoprotectant Dimethyl Sulfoxide on Peripheral Blood-Derived Mesenchymal Progenitor Cells Viability After Cryopreservation

The Effect of Cryoprotectant Dimethyl Sulfoxide on Peripheral Blood-Derived Mesenchymal Progenitor Cells Viability After Cryopreservation

Progenitor cells are mobilized by acute psychological stress but not beta-adrenergic receptor agonist infusion.

Stimuli that activate the sympathetic nervous system, such as acute psychological stress, rapidly invoke a robust mobilization of lymphocytes into the circulation. Experimental animal studies suggest that bone marrow-derived progenitor cells (PCs) also mobilize in response to sympathetic stimulation. Here we tested the effects of acute psychological stress and brief pharmacological β-adrenergic (βAR) stimulation on peripheral PC numbers in humans. In two studies, we investigated PC mobilization in response to an acute speech task (n=26) and βAR-agonist (isoproterenol) infusion (n=20). A subset of 8 participants also underwent the infusion protocol with concomitant administration of the βAR-antagonist propranolol. Flow cytometry was used to enumerate lymphocyte subsets, total progenitor cells, total haematopoietic stem cells (HSC), early HSC (multi-lineage potential), late HSC (lineage committed), and endothelial PCs (EPCs). Both psychological stress and βAR-agonist infusion caused the expected mobilization of total monocytes and lymphocytes and CD8(+) T lymphocytes. Psychological stress also induced a modest, but significant, increase in total PCs, HSCs, and EPC numbers in peripheral blood. However, infusion of a βAR-agonist did not result in a significant change in circulating PCs. PCs are rapidly mobilized by psychological stress via mechanisms independent of βAR-stimulation, although the findings do not exclude βAR-stimulation as a possible cofactor. Considering the clinical and physiological relevance, further research into the mechanisms involved in stress-induced PC mobilization seems warranted.

Histamine receptors expressed in circulating progenitor cells have reciprocal actions in ligation‐induced arteriosclerosis

Histamine is synthesized as a low-molecular-weight amine from L-histidine by histidine decarboxylase (HDC). Recently, we demonstrated that carotid artery-ligated HDC gene-deficient mice (HDC(-/-)) showed less neointimal formation than wild-type (WT) mice, indicating that histamine participates in the process of arteriosclerosis. However, little is known about the roles of histamine-specific receptors (HHRs) in arteriosclerosis. To define the roles of HHRs in arteriosclerosis, we investigated intimal remodeling in ligated carotid arteries of HHR-deficient mice (H1R(-/-) or H2R(-/-)). Quantitative analysis showed that H1R(-/-) mice had significantly less arteriosclerogenesis, whereas H2R(-/-) mice had more, as compared with WT mice. Bone marrow transplantation from H1R(-/-) or H2R(-/-) to WT mice confirmed the above observation. Furthermore, the increased expression of monocyte chemoattractant protein (MCP-1), platelet-derived growth factor (PDGF), adhesion molecules and liver X receptor (LXR)-related inflammatory signaling factors, including Toll-like receptor (TLR3), interleukin-1 receptor (IL-1R) and tumor necrosis factor receptor (TNF-R), was consistent with the arteriosclerotic phenotype of H2R(-/-) mice. Peripheral progenitor cells in H2R(-/-) mice accelerate ligation-induced arteriosclerosis through their regulation of MCP-1, PDGF, adhesion molecules and LXR-related inflammatory signaling factors. In contrast, peripheral progenitor cells act to suppress arteriosclerosis in H1R(-/-) mice, indicating that HHRs reciprocally regulate inflammation in the ligation-induced arteriosclerosis.

Abstract 16991: Endothelial Nitric Oxide Synthase is Essential for Hypoxia-Induced Progenitor Cell Mobilization and Homing

Introduction: Acute myocardial infarction (AMI) is accompanied by induction of pro-angiogenic responses that lead to the recruitment of progenitor cells (PCs). Failure to induce PC mobilization, inefficient homing towards or limited survival in the ischemic microenvironment are all associated with loss in healing capacity and increased scar formation. Hypothesis: Both endothelial nitric oxide synthase (eNOS) and hypoxia-inducible factor-1 (HIF-1) have been implicated in PC biology, angiogenesis and vascular homeostasis. We investigated the effects of eNOS deficiency on HIF-1 and HIF-1 related gene expression, PC mobilization and peripheral PC homing conditions. Methods & Results: AMI was induced in wild-type (WT) (n=10) and eNOS knockout (KO) mice (n=10). One week post-AMI, bone marrow mobilization of early PCs (Lin - Sca-1 + ) was markedly attenuated under eNOS-deficient conditions (p<0.001), as assessed by flow cytometry. mRNA expression of Hif1a (p<0.001) and HIF-1-dependent chemotactic factors, such as Cxcl12 (p<0.001) and Ccl2 (p<0.05), and vascular adhesion molecules, such as Icam1 (p=0.002) and Vcam1 (p<0.001), displayed significantly lower expression in the infarction border zone in eNOS KO mice. eNOS activity was highly correlated with Hif1a expression in WT animals (r=0.876, p<0.0001), a relation that was completely lost in the absence of eNOS. Lin - Sca-1 + PC mobilization was correlated with Hif1a (p=0.01), Cxcl12 (p=0.018) and Ccl2 (p=0.008). Histologically, eNOS KO showed decreased capillary formation in the infarction border zone, which correlated with Hif1a (p=0.007) and Cxcl12 (p<0.001) expression, vascular adhesion molecules Icam1 (p=0.003) and Vcam1 (p=0.018), and with mobilization of Lin - Sca-1 + PCs (p=0.033). Conclusions: eNOS is essential for the mobilization of PCs out of the bone marrow and the expression of hypoxia-induced chemokines and vascular adhesion molecules. We provide evidence for the close relationship between eNOS and HIF-1 pathways and suggest a novel view on PC biology in which nitric oxide acts as an essential cofactor for normal HIF-1 activity, enhancing both PC mobilization and peripheral PC homing conditions.

CD16 antigen is a positive marker of peripheral blood-derived early endothelial progenitor cells

CD16 antigen is a positive marker of peripheral blood-derived early endothelial progenitor cells

Aging Is Not Associated With Bone Marrow-Resident Progenitor Cell Depletion

Changes in progenitor cell biology remain at the forefront of many theories of biologic aging, but there are limited studies evaluating this in humans. Aging has been associated with a progressive depletion of circulating progenitor cells, but age-related bone marrow-resident progenitor cell depletion has not been systematically determined in humans. Patients undergoing total hip replacement were consented, and bone marrow and peripheral progenitor cells were enumerated based on aldehyde dehydrogenase activity and CD34 and CD133 expression. Circulating progenitors demonstrated an age-dependent decline. In contrast, marrow-resident progenitor cell content demonstrated no age association with any progenitor cell subtype. In humans, aging is associated with depletion of circulating, but not marrow-resident, progenitors. This finding has impact on the mechanism(s) responsible for age-related changes in circulating stem cells and important implications for the use of autologous marrow for the treatment of age-related diseases.

Multipotent Adult Progenitor Cell Lines Originating from the Peripheral Blood of Green Fluorescent Protein Transgenic Swine

Multipotent self-renewing stem cell lines have been established using peripheral blood mononuclear cells from adult green fluorescent protein transgenic swine. These cells proliferate as nonadherent spheroids in primordial-specific culture media and readily differentiate into angiogenic, osteogenic, adipogenic, and neurogenic phenotypes when cultured under the appropriate conditions. These cells are designated peripheral blood-derived multipotent adult progenitor cells (PBD-MAPCs). When differentiated in endothelial-specific media, these cells exhibit a cobblestone morphology and express von Willebrand factor (vWF), take up 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarboxyanine-labeled acetylated low-density lipoprotein DiI-Ac-LDL, and form tubes with lumens when grown on pads of Matrigel. Under different culture conditions, the cells appear whorl-like in appearance and express alpha-actin, indicative of smooth muscle phenotype. In the presence of dexamethasone and ascorbic acid, PBD-MAPCs differentiate into cells that produce Alizarin Red-staining extracellular mineral, consistent with an osteogenic potential. Under different conditions the cells produce Oil Red O-staining lipid vacuoles, suggestive of an adipocyte phenotype. We have also developed conditions that induce PBDMAPCs to differentiate into neural cells, confirmed by the expression of specific neuron- and glial-specific markers. Upon transplantation into rat brain, the neurogenic cells survive and migrate throughout the striatum and corpus callosum. The cells remain brightly fluorescent throughout their time in culture, during in vitro differentiation, and after in vivo transplantation. PBD-MAPCs have been maintained in primordial cell media for more than 100 doublings, yet can be induced to differentiate rapidly and efficiently into distinct cell types. PBD-MAPCs are ideal tools to study the mechanisms of differentiation and may be superior to embryonic stem cells as cellular therapeutics.

Treatment of High Risk Diffuse Large B-Cell Lymphomas (DLBCL) with Ntensive Induction Chemotherapy, Rituximab and Autologous Stem Cell Transplant.

Background. Aggressive lymphomas with high-intermediate to high risk according to IPI or age-adjusted IPI (aaIPI) have approximately 50% probability of disease progression in two years. Previous studies of CLSG have shown that intensive induction chemotherapy combined with high-dose chemotherapy and autologous stem cell transplant (ASCT) might be benefitial in these patients (Trneny, Blood 98(11) 682a, 2001). In current study, we have explored the efficacy and tolerability of this regimen in combination with antiCD20 antibody rituximab (R) for DLBCL with 2 or 3 risk factors according to aaIPI.Methods. DLBCL patients of age 18–65 years and aaIPI 2 or 3 were eligible for the study. Treatment protocol consisted of three cycles of high-dose CHOP (MegaCHOP, cytoxan 3 g/m2, doxorubicin 75 mg/m2, vincristin 2 mg, and prednison 300 mg/m2 every 21 days with G-CSF support), followed by three cycles of ESHAP and BEAM with ASCT. Peripheral progenitor cells were collected after first cycle of ESHAP. Four to six doses of R 375 mg/m2 were given on day 1 of induction chemotherapy. As four treatment-related deaths occured in first twenty patients, prephase consisting of AOP (MegaCHOP without cytoxan) was incorporated into the treatment regimen from mid-2003.Results were analysed with intend-to treat approach. Kaplan-Meier curves were constructed for survival analyses. Results. 57 patients were treated from 2002–2004. Median age was 42 years (range, 21–64), and 34 patients were males (60%). 39 patients (67%) had aaIPI 2 and 18 patients (33%) had aaIPI 3. 17 patients had mediastinal variant of DLBCL (30%), and 40 patients (70%) had DLBCL-other. Of 54 evaluable patients, 47 achieved CR or CRu (87%), 5 achieved PR (9%) and two progressed less than three months after treatment completion (4%). Six patients died due to treatment related toxicity (11%), four of them treated without prephase. Three other patients have life-threathening complications (6%). Only one patient (2%) progressed more than one year after study entry. Both 2-year actuarial overall survival (OS) and 2-year event-free survival (EFS) are 79% after median follow-up of 13 months and are not different for aaIPI 2 or 3 patients.Conclusion. Intensive induction chemotherapy combined with rituximab and ASCT is an effective strategy for treatment of young and high risk patients with CD20 positive DLBCLs. The two-year survival rates are higher than expected especially for aaIPI 3 patients. However, the toxicity is quite severe and the advantage of this regimen is to be proven in randomized trials.

Safety control of peripheral blood progenitor cell processing—Eight year-survey of microbiological contamination and bag ruptures in a single institution

Background and objectives Recipients of peripheral blood progenitor cells (PBPC) are prone to opportunistic infections and their lives depend upon the availability of PBPC. Centres responsible for PBPC processing are committed to provide patients with products which are as safe as possible. These must be processed under quality assurance requirements. Materials and methods A retrospective analysis of PBPC processed in a single centre according to quality assurance premises was carried out to define the rate and the cause of microbiologic contamination and bag ruptures. Results 940 microbiologic cultures were run on 725 cryopreserved bags. Five bacterial strains were identified in the positive cultures. The rate of bacterial contamination was 1.85% of the patients, 0.34% of the collected bags, and 0.79% of the reinfused bags. Bag ruptures occurred in 1.06% of the thawed bags. Conclusions Permanent quality control of peripheral progenitor cell processing is mandatory. Preventive measures such as ex vivo cell manipulation in a clean room facility and the use of a double-bagged technique are highly recommended to prevent bacterial contamination and to rescue progenitor cells in the case of a bag rupture if those cells are necessary for the haematopoietic reconstitution of a patient.

Peripheral CD34+ Cells and the Risk of In-Stent Restenosis in Patients With Coronary Heart Disease

In-stent restenosis represents the major limitation of percutaneous coronary revascularization. The underlying neointimal hyperplasia mainly consists of smooth muscle cells (SMCs), which can be derived from bone marrow cells. We hypothesized that changes in the peripheral progenitor cell counts after coronary stenting may predict the development of restenosis. We prospectively studied men with atherosclerotic coronary artery disease who had undergone successful elective stenting of solitary target lesions (n = 17). Peripheral blood samples were drawn at baseline (before stenting) and 1 day after stenting. The CD34+ cell count was determined by flow cytometry. Follow-up quantitative coronary angiography was performed after 8.1 +/- 2.6 months. Except for longer primary lesions in patients with angiographic restenosis, no significant differences in patient and lesion characteristics were seen. The rate of restenosis (75% vs 11%, p = 0.015) and the extent of diameter stenosis at follow-up (56.9 +/- 26.9% vs 26.5 +/- 16.5%, p = 0.012) were higher in patients with a postprocedural increase in CD34+ cells than in those with a decrease in CD34+ cells. Postprocedural CD34+ cell counts were increased in patients with restenosis but decreased in those without restenosis (p = 0.002). A robust correlation was seen between the change in CD34+ cells and late lumen loss (r = 0.65, p <0.005). In a multivariate regression model, the change in CD34+ cells, lesion length, and preprocedural minimal lumen diameter independently predicted for late lumen loss. In conclusion, an increase in circulating CD34+ cells after coronary stenting constitutes an independent risk factor predicting in-stent restenosis and may be suggestive of their involvement in neointimal hyperplasia.

Bone marrow CD34+ cell count is predictive for adequate peripheral progenitor cell collection

Several studies have investigated the influence of clinical and biological variables on mobilisation of peripheral blood progenitor cells (PBPCs). The aim of this study was to evaluate the role of steady-state bone marrow (BM) CD34+ cells as a predictive parameter of PBPC yield. We studied 90 patients with multiple myeloma (MM) (41 patients), non-Hodgkin’s lymphoma (NHL) (25 patients) or acute myeloid leukaemia (AML) (24 patients), mobilised with chemotherapy and growth factor. The median time from first treatment to mobilisation was 5 months. Only one patient was previously exposed to alkylating agents. The median BM CD34+ count at mobilisation was 833 μl −1 (range:1.4–15.540) corresponding to 1.51% of mononuclear cells (range: 0.02–8.6). Sixty-six patients (73%) reached the optimal target of 4 × 10 6 kg −1 CD34+ cells with 1 (18 patients), 2 (42 patients) or 3 leukaphereses (6 patients). Eleven patients (12%) mobilised less than 4 × 10 6 kg −1 CD34+ cells and 13 (15%) failed mobilisation. Among the laboratory and clinical parameters evaluated at the time of mobilisation, only BM CD34+ count was a predictive factor for adequate collection ( P = 0.04), particularly in MM patients ( P = 0.003). In this setting, a BM concentration of CD34+ cells lower than 66 μL −1 was associated with a higher probability of inadequate collection.

Comparison of two continuous-flow systems for the collection of peripheral progenitor cells.

New advances in apheresis technology allow for the safe and efficient collection of peripheral progenitor cells (PPC). Two blood cell separators were compared with respect to separation results such as PPC yield and contamination of the products. A total of 11 patients (6 multiple myeloma, 4 non-Hodgkin lymphoma, and 1 medulloblastoma) underwent PPC collections with either the Amicus (Baxter) or AS. TEC (Fresenius) blood cell separator. PPC were mobilized by chemotherapy and granulocyte colony-stimulating factor (G-CSF) application. Blood counts were determined before and after apheresis as well as in the PPC product. CD34 antigen-expressing cells were measured in the peripheral blood and in the PPC product by flow cytometry. Median baseline CD34 antigen-expressing cells were higher in patients undergoing PPC collection with the Amicus device. More PPC/kg of body weight were collected with this machine (5.3 x 10(6)/kg body weight versus 1.7 x 10(6) in the AS. TEC). The median volume was 129 ml (range 80-156 ml) for Amicus products and 111 ml (range 66-202 ml) for the AS. TEC, respectively. The median platelet contamination of the products from the Amicus blood cell separator was significantly lower than in products from the AS. TEC machine (0.17 x 10(11) versus 0.65 x 10(11), p < 0.001). The data show that a higher yield of PPC was collected with the Amicus machine. The platelet contamination of the products obtained from the two blood cells separators was significantly different.

Comparison of Two Continuous-Flow Systems for the Collection of Peripheral Progenitor Cells

New advances in apheresis technology allow for the safe and efficient collection of peripheral progenitor cells (PPC). Two blood cell separators were compared with respect to separation results such as PPC yield and contamination of the products. A total of 11 patients (6 multiple myeloma, 4 non-Hodgkin lymphoma, and 1 medulloblastoma) underwent PPC collections with either the Amicus (Baxter) or AS.TEC (Fresenius) blood cell separator. PPC were mobilized by chemotherapy and granulocyte colony-stimulating factor (G-CSF) application. Blood counts were determined before and after apheresis as well as in the PPC product. CD34 antigen-expressing cells were measured in the peripheral blood and in the PPC product by flow cytometry. Median baseline CD34 antigen-expressing cells were higher in patients undergoing PPC collection with the Amicus device. More PPC/kg of body weight were collected with this machine (5.3 × 106/kg body weight versus 1.7 × 106 in the AS.TEC). The median volume was 129 ml (range 80-156 ml) for Amicus products and 111 ml (range 66-202 ml) for the AS.TEC, respectively. The median platelet contamination of the products from the Amicus blood cell separator was significantly lower than in products from the AS.TEC machine (0.17 × 1011 versus 0.65 × 1011, p < 0.001). The data show that a higher yield of PPC was collected with the Amicus machine. The platelet contamination of the products obtained from the two blood cells separators was significantly different.

Collection of peripheral progenitor cells: a comparison between Amicus and Cobe-Spectra blood cell separators

The authors compared the efficiency of two different blood cell separators (Amicus and Cobe-Spectra) in collecting peripheral blood progenitor cells for autologous or homologous transplantation. A total number of 129 procedures were performed, 36 with Spectra, 93 with Amicus. There was no difference between Spectra and Amicus efficiencies for CD34+ cell collection (46.685% vs 46.235%; p=n.s) but the platelet efficiencies were 17.31% and 12.54% respectively ( p=0.04) and, if autologous and allogeneic collections were considered separately, a marked difference resulted in allogeneic platelet efficiency between 6 Spectra and 23 Amicus procedures (26.83% vs 8.68%, p=0.0004). The authors were able to demonstrate that in 70 Amicus autologous collections there was a different platelet efficiency, if peripheral count was considered: 12 procedures performed with a platelet count > 100 × 10 9/l had a very low efficiency (6.86%), but this value increased if platelet count lowered (13.02% if between 100 and 50 × 10 9/l, 22.63% if between 50 and 0 × 10 9/l, 23 and 35 procedures respectively). The study is preliminary and the number of collections is little, but the overall data suggest that Spectra (AutoPBSC, V 6.0) and Amicus separators have the same efficiency for collecting CD34+ cells while Amicus procedures have a very low platelet contamination, especially with donors.

Collection of peripheral progenitor cells in paediatric patients with a new programme for the collection of mononuclear cells.

When harvesting peripheral progenitor cells (PPC) in children, the special situation of their circulatory system has to be taken into account. Therefore, extracorporeal blood volume and product volume should be small to avoid side effects. Nine children (age 2-14 years, weight 12.8-58.5 kg) with malignancies underwent 10 PPC collections with the MNC programme of the Amicus blood cell separator. The disposable kit was primed with red blood cells (RBCs) or human albumin to avoid circulatory side effects. The children were monitored for blood pressure and heart rate during the whole apheresis procedure. A median blood volume of 4,577 ml (range 3,536-8,596 ml) was processed in a separation time of 270 min (range 176-331 min). The median product weight was 81 g (range 53-107 g) and the yield of CD 34 antigen expressing cells was 12.5 x 10(6)/kg body weight (range 1.8-26 x 10(6)/kg body weight). Only one child had to undergo a second apheresis to collect the desired transplantation dose. The median platelet contamination of the product was 0.32 x 10(11) (0.13-0.85 x 10(11)). No circulatory side effects were observed. Blood flow alarms occurred in seven of ten aphereses and one collection had to be terminated due to insufficient flow. PPC can be efficiently collected in children with the MNC programme without circulatory side effects. The platelet contamination of the product was low due to the elutriation principle of the collection process, thereby avoiding thrombocytopenic bleeding episodes in the patients.

Effect of alpha-FMH and DPPE on colony-forming properties of human peripheral progenitor cells.

Endogenous histamine regulates the haematopoiesis. Histidine decarboxylase inhibitor decreases the histamine level, and its intracellular antagonist decreases the histamine effect. The effect of histidine decarboxylase inhibitor (alpha-fluoromethyl histidine) and the intracellular antagonist of histamine [N'N-diethyl-2-4-(phenylmethyl) phenoxyethan-amine-HCl] was investigated on the colony-forming ability of human peripheral progenitor cells. Semi-solid culture medium was used both in the presence and in the absence of 3 U/ml erythropoietin. alpha-Fluoromethyl histidine was used in the range of 50 through 150 micro Mol/ml, the concentration of N'N-diethyl-2-4-(phenylmethyl) phenoxyethanamine-HCl was between 5 and 25 micro Mol/ml. The number of both the erythroide and the granulocyte macrophage colony was significantly decreased in a concentration dependent manner by the presence of both N'N-diethyl-2-4-(phenylmethyl) phenoxyethanamine-HCl (in all concentrations used) and &alpha-fluoromethyl histidine (at higher concentration). The inhibitory effect was decreased by erythropoietin.

Adverse events in peripheral progenitor cell collection: a 7-year experience.

Collection of peripheral progenitor cells (PPC) by apheresis machines is generally regarded as a safe procedure. However, data about adverse events in PPC harvesting are scarce. In a monocentric retrospective study, the data of 540 PPC collections in a period of 7 years were reviewed. Adverse events were subdivided in collection-associated technical problems and patient/donor-related side effects. Patient/donor-related side effects occurred most often (19.8%); most of them were paresthesias due to citrate toxicity. Paresthesias were treated by oral (20.4%) or intravenous (1.1%) calcium supplementation. Problems with venous access were also seen frequently, resulting in blood flow alarms (11.3%) and blockades in the return line (4.3%). A total of 6.9% of these problems were catheter associated, requiring revision of the central venous line in 2.6%. Technical problems with the blood cell separators were observed in 11.7%. Ten PPC collections were discontinued due to adverse events. The data of this retrospective, monocentric analysis show that patient/donor-associated problems were observed in every fifth PPC harvest. Most of them were paresthesias, which could be easily treated by calcium supplementation. Problems with venous access and technical problems with the cell separators occurred in every tenth PPC collection.

Colledction of Peripheral Progenitor Cells in Pediatric Patients with Reduced Volume Technique

Background: When peripheral progenitor cells (PPC) are harvested in children the special situation of their circulatory system has to be taken into account. Extracorporeal blood volume and product volume should be low to avoid side effects. Setting: Hemapheresis unit and pediatric oncologic ward of a University Clinic. Patients: 12 children with neuroblastoma, Ewing sarcoma, unclassified malignant bone tumor, medulloblastoma, pheochromocytoma, rhabdomyosarcoma and Wilms tumor. Material and Methods: The children underwent 24 PPC collections with a continuous flow system and a reduced volume programme. PPC were mobilized by chemotherapy and G-CSF application. Blood counts and CD34 antigen-expressing cells were determined before apheresis and in the PPC product. PPC were frozen at controlled rates and stored in liquid nitrogen until they were used for autologous transplantation. Results: Except for anticoagulant-induced venous irritation, no adverse side effects were observed. The median product volume was 59 ml (range 34–119 ml) and the yield of CD34 antigen-expressing cells was 1.9 × 10⁶/kg body weight (0.1 × 10⁶– 20.4 × 10⁶/kg). The platelet contamination of the products was 0.25 × 10¹¹(0.05 × 10¹¹–1.43 × 10¹¹). Median hematopoietic reconstitution for platelets was achieved on day 27 after transplantation and for leukocytes on day 10.5, respectively. Conclusion: PPC can be easily collected in children with the reduced product volume technique. The system is adopted to the small blood volume of infants so that no circulatory side effects were observed. The reduced volume technique helps lessening the quantity of dimethylsulfoxide needed for cryopreservation as well as reducing storage space. Platelet contamination of the product was low due to retransfusion of platelet-rich plasma to the patients prior to PPC harvesting.