Transplantation of allogeneic CD34-selected stem cells after fludarabine-based conditioning regimen for children with mucopolysaccharidosis 1H (M. Hurler)

doi:doi:10.1038/sj.bmt.1704786

Bone Marrow Transplantation (2005) 35, 265–269. doi:10.1038/sj.bmt.1704786 Published online 6 December 2004

Transplantation of allogeneic CD34-selected stem cells after fludarabine-based conditioning regimen for children with mucopolysaccharidosis 1H (M. Hurler)

L Grigull¹, A Beilken¹, M Schrappe¹, A Das², T Luecke², A Sander¹, M Stanulla¹, K Rehe¹, M Sauer¹, H Schmid¹, K Welte¹, Z Lukacs³, A Gal⁴ and K W Sykora¹

¹Pediatric Hematology and Oncology, Children's Hospital, Hannover Medical University, Hannover, Germany
²Pediatric Metabolic Disease Section, Children's Hospital, Hannover Medical University, Hannover, Germany
³Metabolic Laboratory, Department of Pediatrics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
⁴Institute of Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany

Correspondence: Dr L Grigull, Pediatric Hematology and Oncology, Children's Hospital, Hannover Medical University, Carl-Neuberg-Str. 1, OE 6780, Hannover, Germany. E-mail: Grigull.Lorenz@mh-hannover.de

Received 29 April 2004; Accepted 25 October 2004; Published online 6 December 2004.

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Abstract

Hurler syndrome (MPS1H) is a progressive inborn error of mucopolysaccharide metabolism leading to premature death. Allogeneic hematopoietic cell transplantation (HCT) can achieve stabilization and improve long-term survival. However, large studies have shown that preparative regimen-related toxicity (RRT) and graft failure rates have been relatively high. We transplanted five Hurler children with a fludarabine-based conditioning regimen, consisting of fludarabine/busulphan/ATG for matched family donor (MFD), with the addition of melphalan for mismatched family donor and matched unrelated donor (MUD) transplantations. Median age at HCT was 27 months (range 10–36). The source of stem cells was bone marrow in one MFD and CD34-selected PBSC in four patients. Median CD34+ cell dose was 25 $times$ 10⁶/kg (range 11.5–54). No RRT >grade II was observed. All patients are surviving at a median of 32 months (range 14–41) and show sustained donor engraftment with 3/5 having full donor chimerism, and 2/5 mixed chimerism (>85%). We conclude that this regimen is feasible and has low toxicity in Hurler children. In combination with high doses of CD34+ selected cells (>10 $times$ 10⁶/kg) and donor lymphocyte infusions, stable engraftment could be achieved in unrelated and mismatched related transplantations.

Keywords:

mucopolysaccharidosis, CD34+ selection, donor lymphocyte infusion, fludarabine

Hurler syndrome (MPS1H) is an autosomal recessive inborn error of metabolism due to a deficiency of alpha-L-iduronidase activity. Clinical manifestations include hepatosplenomegaly, progressive mental deterioration, hydrocephalus, cardiac disease with coronary insufficiency, airway compromise, vision and hearing impairment, and severe skeletal deformations. Untreated patients develop progressive mental retardation and multisystem morbidity with a median life expectancy of 5 years.¹ Enzyme replacement therapy (ERT) is of limited benefit in patients with MPS1H as the enzyme does not freely cross the blood–brain barrier though it could ameliorate limitations in joint range of motion, pulmonary function, and in the airway. To date, hematopoietic stem cell transplantation (HCT) from an allogeneic donor represents the only proven therapy that can prolong survival and either reverse or stabilize disease manifestations.^2,3,4 However, over the years it has been shown that these patients are especially prone for two complications of allogeneic HCT: graft failure and regimen-related toxicity (RRT). As reported by the North American Storage Disease Collaborative Study Group, the likelihood of graft failure was 15% in cases of HLA fully matched sibling donor and up to 37% when an unrelated donor was used.^2,3,5 Although the preparative regimens of these studies varied, both over time and between transplant centers, most patients received a combination including busulphan and cyclophosphamide with or without T-cell depletion of the graft. Cyclophosphamide predominantly has been included in preparative regimens for its potent immunosuppressive activity. However, in combination with busulphan and TBI, regimen-related toxicities including the lungs have been significant. Specific metabolites of cyclophosphamide are associated with increased toxicity and mortality after conditioning, especially in combination with total-body irradiation,⁶ where cardiac toxicity is especially dangerous for Hurler patients. These experiences provide the rationale to substitute cyclophosphamide with less toxic immunosuppressive agents that have the potential to mediate sustained engraftment after allogeneic HCT. Fludarabine is a purine analog with known inhibitory effects on lymphocyte proliferation. This drug has shown very few extramedullary toxicities in dose ranges between 90 and 125 mg/m², although side effects involving the central nervous system are known to occur at higher doses.^7,8 To ensure sufficient myeloablation for engraftment of T-cell-depleted PBSC, melphalan was substituted for cyclophosphamide because of its lower cardiotoxicity.⁹

The goal of this study was to determine whether a combination of 180 mg/m² fludarabine and 16 mg/kg intravenous busulphan over 4 days plusminus 140 mg/m² melphalan and ATG can provide sustained engraftment after allogeneic HCT from related and unrelated donors without an increased incidence and severity of transplant-related complications.

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Patients

All patients had signs and symptoms consistent with Hurler syndrome. The diagnosis was confirmed by increased excretion of dermatan and heparan sulfate in the urine and deficiency of alpha-L-iduronidase activity in leukocytes. Patient characteristics are presented (Table 1). The parents of all patients were aware of the experimental nature of the treatment and gave their informed consent to it.

Table 1 - Children's characteristics.

Full table

Donors and grafts

Except for patient 1, a HLA-matched family donor could not be found. In patients 2 and 3, the mothers were chosen. In patient 2 the mother had only one DR allele mismatch and in patient 4 she had a 3/8 antigen mismatch. In patients 4 and 5, we chose an unrelated donor. Patient 5 had an HLA-C mismatch and patient 4 was a full 10/10 antigen match (Table 2). No Class-I high-resolution typing was performed at the time. After informed consent, the donors^2,3,4,5 underwent peripheral blood stem cell collection after G-CSF mobilization.

Table 2 - HLA-constellation, cell doses, engraftment and aGvHD.

Full table

All apheresis products were T-cell depleted by positive magnetic selection of CD34+ cells using the CliniMACS sorting device (Miltenyi Biotec, Bergisch Gladbach, Germany). The median cell doses transplanted were 25 $times$ 10⁶ CD34+ cells/kg (range 19.5–54) and 3.8 $times$ 10⁴ CD3+ cells/kg (range 1.3–5.9).

Transplantation procedure and engraftment

All patients were prepared using fully myeloablative regimens. All patients were given intravenous busulphan (Busulfex®, 4 mg/kg/day, days –8 to –5, total dose 16 mg/kg), fludarabine (30 mg/m²/day, days –10 to –5, total dose 180 mg/m²), and antithymocyte globulin (ATG rabbit Fresenius® 10 mg/kg/day, days –4 to –1, total dose 40 mg/kg). In patients 3, 4, and 5, melphalan (4 mg/kg, day -5) was added as a HLA-mismatched or unrelated donor was used. The high dose of Busulfex® (16 mg/kg), which is equivalent to 20 mg/kg of oral busulphan, was given because all patients were under 3 years of age. Infusion of the thawed CD34+ cells (patients 2–5) or fresh bone marrow (patient 1) was tolerated without side effects. Patient 1 received cyclosporin A as GvHD prophylaxis until day +120. In patients 2–5, no additional GvHD prophylaxis was given after transplantation, but cyclosporin A was given during conditioning (days –10 to –1, 1 mg/kg/day divided in two doses) to reduce cytokine release.¹⁰ Granulocyte engraftment was seen in all patients, with a median time to reach >0.5/nl granulocytes after 16 days.^{10,11,12,13,14,15,16,17,18,19,20,21} Platelet counts >50/nl were reached after a median of 20 days. Details are given in Table 2.

Outcome

All five patients transplanted for MPS1H are in ambulatory care, with a median follow-up of 32 months (range 14–41). In patients 4 and 5, a cytomegalovirus reactivation necessitated antiviral therapy. Acute GvHD >I was not seen, all patients are free of chronic GvHD. No serious infections were observed. In patient 2, a subdural hematoma on day +6 after HCT required surgical intervention, but no long-term adverse sequelae were observed.

All patients have a donor chimerism >85%. In patients 2, 4, and 5, donor–lymphocyte infusions (DLI) were administered due to decreasing donor chimerism (see Table 3). Two DLI were given in patients 2 and 5, and one DLI in patient 4 (median CD3+ cell dose 3 $times$ 10⁴/kg).

Table 3 - Serial results of the chimerism analysis in patients 2, 4, 5 and donor–lymphocyte infusions.

Full table

All patients have stable graft function; patient 4 experienced a transient thrombopenia requiring one platelet transfusion, the thrombopenia resolved spontaneously.

Biochemical investigation of leukocyte iduronidase showed normalized or increased activity after HCT, depending on the donor. In patients 2 and 3, where the heterozygous mothers served as donors, iduronidase activity was about 50% of normal. Glycosaminoglycan excretion, which was increased before HCT, returned to normal values after HCT.

The neuropsychological development is improving in all patients although all of them show mild to pronounced psychomotor retardation. Magnetic resonance imaging revealed a variety of pathological features in the five patients prior to HCT including hydrocephalus and cystic white matter lesions. In all patients, a regression of intracranial lesions could be seen after HCT.

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Discussion

We present first results on five children with Hurler syndrome who received a fludarabine-based radiation-free conditioning regimen for allogeneic HCT. After a median follow-up time of 32 months all children are alive, have experienced only mild treatment-related toxicity, and show sustained donor derived hematopoiesis.

Based on the genotype of the five patients, a severe course of disease with rapid progression was expected. Q70X and W402X (patients 1 and 3) are two mutations common among patients with MPS1H, both encode functional null alleles, and are usually associated with a severe phenotype in homozygous condition.¹¹ Patients 4 and 5, two cousins, are compound heterozygotes for the null mutation W402X and the missense change A79V. Recombinant A79V IDUA expressed in CHO cells was detected in extremely low amounts (0.1% of wild-type IDUA), suggesting that the enzyme produced from this allele has no activity either.¹² Similarly, a severe course of MPS1 can be predicted by the genotype of patient 2. This boy is compound heterozygote for a likely functional null allele, due to a 1 bp deletion that causes frameshift, and subsequent premature termination of protein translation, and a deletion of 21 nucleotides, that should result in the absence of seven amino acids in a functionally important portion of the protein.

The primary goal of therapy of children with Hurler syndrome is long-term survival with an improved quality of life. Currently, HCT provides the only prospect for long-term survival with preserved intellectual function in these children and early timing of HCT has shown to be crucial to achieve a satisfying outcome.^2,4,5,13 Good long-term results, however, are hampered by a relatively high incidence of graft failure and RRT. The cause for the increased incidence of graft failure has not been well understood. Investigators have hypothesized a relatively normal immune function pre transplant, an abnormal bone marrow microenvironment,⁴ and an accelerated busulphan clearance,¹⁴ although the latter has not been supported by more recent work.¹⁵

To date, the results of the North American Storage Disease Collaborative Study Group represent the largest experience with allogeneic HCT in children with Hurler syndrome. The incidence of graft failure was as high as 15% when a HLA-genotypically identical sibling donor was used. In the unrelated setting, graft failure rate reached 37%.^2,3 A large percentage of patients reported in these studies were transplanted at the University of Minnesota. Preparative regimens used at this institution in the unrelated setting before included a combination of busulphan, cyclophosphamide, TBI and ATG. Although engraftment rates were encouraging, there was a significant increase in RRT including the lungs.¹⁶ Based on these data, the pilot protocol MHH-Hurler was developed with the objective of increasing the proportion of patients who attain full engraftment, especially if this could be accomplished with minimal toxicity.

In our patients with MPS1H, we used a myeloablative conditioning regimen consisting of fludarabine, busulphan and antithymocyte globuline. Standard total doses of ATG Fresenius for the prevention of GvH in MUD donors are between 60 and 90 mg/kg, where the 60 mg/kg given here is on the lower end of this range. Finke et al used up to 60 plusminus 90 mg/kg b.w. prior to transplantation, in addition to cyclosporin A and short-course methotrexate.¹⁷ Melphalan was added in MUD or MMUD donors. Intravenous busulphan was used to ensure more reliable drug exposure with erratic oral absorption.^18,19 High-dose melphalan has been shown to be an effective component of preparative regimens to induce durable remissions in patients with acute leukemia and other hematologic malignancies with little extramedullary toxicity.^20,21,22 In addition, purine analogs such as fludarabine inhibit the mechanisms of DNA repair after alkylator-induced damage.⁷ Several reports have noted that a fludarabine-based conditioning regimen was well tolerated in children with very mild toxicity and no major transplant-related complications or >grade II graft-versus-host disease.²³ A recent report from Staba et al provided data on cord blood transplantation in children with MPS1H. In that report, all children were fully engrafted, two children died in the context of a variety of complications including viral infections, hemolytic anemia and pulmonary hemorrhage.²⁴ We observed no transplant-related mortality and only one patient experienced a life-threatening situation. Notably, there was no pulmonary toxicity in our series. Pulmonary toxicity is a well-known complication in patients with MPS1H receiving a full marrow graft and busulphan-cyclophosphamide conditioning.^2,3 This lack of toxicity is likely due to the omission of cyclophosphamide in our regimen, presumably resulting in reduction in its specific alkylator toxicity. Also, pulmonary complications are less common in T-cell-depleted transplantations in general.²⁵ In the specific case of MPS1H, intensive GvHD-prophylaxis with ATG and/or T-cell depletion may result in the regeneration of alloreactive T-cells at a time when mucopolysaccharides are already cleared from the lungs. T-cell-mediated pulmonary injury may thus be minimized by having the lungs in a less inflammatory state at the time of T-cell reconstitution. As illustrated in our patients, the intensified T-cell depletion did not lead to unusual infectious complications. Heart failure and sudden cardiac death, commonly attributed in Hurler patients to cyclophosphamide cardiotoxicity,^2,3 were also not observed in our series. However, a recent report showed a reversible cardiotoxicity in patients receiving the combination of fludarabine and melphalan.²⁶ Intravenous busulphan proved safe with respect to CNS complications (eg in sickle cell patients) and was therefore included in our protocol.¹⁹

Engraftment was seen in all five children after a median of 16 days and the grafts were maintained after a median follow-up period of 27 months. Peters et al³ reported on an engraftment rate of 85% in HLA-identical sibling HCT patients and 65% in HLA haploidentical patients with a total probability of survival of 64% after 5 years. Guffon et al¹³ observed a graft failure in 3/13 patients after HLA-mismatched HCT using a conditioning regimen containing busulphan and cyclophosphamide, once more illustrating the inherent problems of nonengraftment after HCT in children with MPS1H. In contrast to this, we used the concept of megadoses of CD34+ selected cells, which resulted in lower GvHD rates and quick engraftment even in the haploidentical setting.^27,28 Kremens et al²⁹ reported on six children with nonmalignant diseases who received a CD34+ selected graft from a parental donor. No GvHD >II, no transplant-related mortality, and timely engraftment were reported in this series.

Decreasing donor chimerism was observed in three patients between days +61 and +196 after HCT. Donor lymphocyte infusions have been advocated for converting mixed chimerism into full chimerism.^30,31 It has become clear that DLI can be reasonably safe and effective, even after mismatched HCT, when small enough CD3+ cell doses are used. Woodard et al³² provided data on children with refractory aplastic anemia who received DLI (2.5 $times$ 10⁴/kg CD3+ cells) after haploidentical HCT. Similar experiences were reported by Bader et al,^30,31 who could show for children with malignant hematological diseases that immunotherapy is an effective tool to suppress relapses.

Using a decline of donor-derived hematopoiesis over time as an indication for DLI, the administration of donor lymphocyte infusions was incorporated into our transplant protocol. DLI was given at a median dose of 3 $times$ 10⁴/kg (range 2.5–5) CD3+ cells, resulting in an increased donor derived hematopoiesis. GvHD after DLI was not seen in our patients. This supports the notion that after CD34+-selected HCT, the application of DLI might be a safe therapeutic option in overcoming the problems of rejection in Hurler patients. However, as there are reports on the occurrence of delayed chronic GVHD after DLI, they have to be used with caution. The role of DLI in the setting of inborn metabolic diseases deserves further study.

Although the authors are aware of the small patient number, these first results are encouraging in that HCT for children with Hurler syndrome is feasible using a fludarabine-based radiation-free preparative regimen. Furthermore, on the presented treatment protocol, DLI has shown the potential to stabilize and finally rescue the graft in children that are at risk for graft rejection, a feared and well-known problem in Hurler patients after allogeneic HCT. The data will be the basis for further prospective studies in larger patient cohorts.

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References

References

1.	Beck M. Variable clinical presentation in lysosomal storage disorders. J Inherit Metab Dis 2001; 24 Suppl 2: 47−51. \| Article \| PubMed \|
2.	Peters C, Balthazor M & Shapiro EG et al. Outcome of unrelated donor bone marrow transplantation in 40 children with Hurler syndrome. Blood 1996; 87: 4894−4902. \| PubMed \| ChemPort \|
3.	Peters C, Shapiro EG & Anderson J et al. Hurler syndrome: II. Outcome of HLA-genotypically identical sibling and HLA-haploidentical related donor bone marrow transplantation in fifty-four children. The Storage Disease Collaborative Study Group. Blood 1998; 91: 2601−2608. \| PubMed \| ISI \| ChemPort \|
4.	Peters C, Shapiro EG & Krivit W. Neuropsychological development in children with Hurler syndrome following hematopoietic stem cell transplantation. Pediatr Transplant 1998; 2: 250−253. \| PubMed \| ChemPort \|
5.	Grewal SS, Krivit W & Defor TE et al. Outcome of second hematopoietic cell transplantation in Hurler syndrome. Bone Marrow Transplant 2002; 29: 491−496. \| Article \| PubMed \| ChemPort \|
6.	McDonald GB, Slattery JT & Bouvier ME et al. Cyclophosphamide metabolism, liver toxicity, and mortality following hematopoietic stem cell transplantation. Blood 2003; 101: 2043−2048. \| Article \| PubMed \| ChemPort \|
7.	Chun HG, Leyland-Jones B & Cheson BD. Fludarabine phosphate: a synthetic purine antimetabolite with significant activity against lymphoid malignancies. J Clin Oncol 1991; 9: 175−188. \| PubMed \| ChemPort \|
8.	Keating MJ, O'Brien S & Lerner S et al. Long-term follow-up of patients with chronic lymphocytic leukemia (CLL) receiving fludarabine regimens as initial therapy. Blood 1998; 92: 1165−1171. \| PubMed \| ISI \| ChemPort \|
9.	Nieto Y & Vaughan WP. Pharmacokinetics of high-dose chemotherapy. Bone Marrow Transplant 2004; 33: 259−269. \| Article \| PubMed \| ChemPort \|
10.	Schmidt J, Fleissner S & Heimann-Weitschat I et al. Effect of corticosteroids, cyclosporin A, and methotrexate on cytokine release from monocytes and T-cell subsets. Immunopharmacology 1994; 27: 173−179. \| Article \| PubMed \| ChemPort \|
11.	Scott HS, Bunge S & Gal A et al. Molecular genetics of mucopolysaccharidosis type I: diagnostic, clinical, and biological implications. Hum Mutat 1995; 6: 288−302. \| PubMed \| ChemPort \|
12.	Yogalingam G, Guo XH & Muller VJ et al. Identification and molecular characterization of alpha-L-iduronidase mutations present in mucopolysaccharidosis type I patients undergoing enzyme replacement therapy. Hum Mutat 2004; 24: 199−207. \| Article \| PubMed \| ChemPort \|
13.	Guffon N, Souillet G & Maire I et al. Follow-up of nine patients with Hurler syndrome after bone marrow transplantation. J Pediatr 1998; 133: 119−125. \| PubMed \| ChemPort \|
14.	Vassal G, Fischer A & Challine D et al. Busulfan disposition below the age of three: alteration in children with lysosomal storage disease. Blood 1993; 82: 1030−1034. \| PubMed \| ChemPort \|
15.	Jacobson P, Park JJ & Defor TE et al. Oral busulfan pharmacokinetics and engraftment in children with Hurler syndrome and other inherited metabolic storage diseases undergoing hematopoietic cell transplantation. Bone Marrow Transplant 2001; 27: 855−861. \| Article \| PubMed \| ChemPort \|
16.	Krivit W, Aubourg P, Shapiro E & Peters C. Bone marrow transplantation for globoid cell leukodystrophy, adrenoleukodystrophy, metachromatic leukodystrophy, and Hurler syndrome. Curr Opin Hematol 1999; 6: 377−382. \| Article \| PubMed \| ChemPort \|
17.	Finke J, Bertz H & Schmoor C et al. Allogeneic bone marrow transplantation from unrelated donors using in vivo anti-T-cell globulin. Br J Haematol 2000; 111: 303−313. \| Article \| PubMed \| ChemPort \|
18.	Dalle JH, Wall D & Theoret Y et al. Intravenous busulfan for allogeneic hematopoietic stem cell transplantation in infants: clinical and pharmacokinetic results. Bone Marrow Transplant 2003; 32: 647−651. \| Article \| PubMed \| ChemPort \|
19.	Nguyen L, Fuller D & Lennon S et al. I.V. busulfan in pediatrics: a novel dosing to improve safety/efficacy for hematopoietic progenitor cell transplantation recipients. Bone Marrow Transplant 2004; 33: 979−987. \| Article \| PubMed \| ChemPort \|
20.	Sarosy G, Leyland-Jones B, Soochan P & Cheson BD. The systemic administration of intravenous melphalan. J Clin Oncol 1988; 6: 1768−1782. \| PubMed \| ChemPort \|
21.	Singhal S, Powles R & Treleaven J et al. Melphalan alone prior to allogeneic bone marrow transplantation from HLA-identical sibling donors for hematologic malignancies: alloengraftment with potential preservation of fertility in women. Bone Marrow Transplant 1996; 18: 1049−1055. \| PubMed \| ChemPort \|
22.	Taha IA, Ahmad RA & Rogers DW et al. Pharmacokinetics of melphalan in children following high-dose intravenous injection. Cancer Chemother Pharmacol 1983; 10: 212−216. \| Article \| PubMed \| ChemPort \|
23.	Jacobsohn DA, Duerst R, Tse W & Kletzel M. Reduced intensity haemopoietic stem-cell transplantation for treatment of non-malignant diseases in children. Lancet 2004; 364: 156−162. \| Article \| PubMed \|
24.	Staba SL, Escolar ML & Poe M et al. Cord-blood transplants from unrelated donors in patients with Hurler's syndrome. N Engl J Med 2004; 350: 1960−1969. \| Article \| PubMed \| ChemPort \|
25.	Ho VT, Weller E & Lee SJ et al. Prognostic factors for early severe pulmonary complications after hematopoietic stem cell transplantation. Biol Blood Marrow Transplant 2001; 7: 223−229. \| Article \| PubMed \| ChemPort \|
26.	Ritchie DS, Seymour JF & Roberts AW et al. Acute left ventricular failure following melphalan and fludarabine conditioning. Bone Marrow Transplant 2001; 28: 101−103. \| Article \| PubMed \| ChemPort \|
27.	Reisner Y & Martelli MF. Tolerance induction by 'megadose' transplants of CD34+ stem cells: a new option for leukemia patients without an HLA-matched donor. Curr Opin Immunol 2000; 12: 536−541. \| Article \| PubMed \| ISI \| ChemPort \|
28.	Lang P, Klingebiel T & Bader P et al. Transplantation of highly purified peripheral-blood CD34+ progenitor cells from related and unrelated donors in children with nonmalignant diseases. Bone Marrow Transplant 2004; 33: 25−32. \| Article \| PubMed \| ChemPort \|
29.	Kremens B, Basu O & Peceny R et al. Allogeneic CD34+-selected peripheral stem cell transplantation from parental donors in children with non-malignant diseases. Bone Marrow Transplant 2002; 29: 9−13. \| Article \| PubMed \| ChemPort \|
30.	Bader P, Klingebiel T & Schaudt A et al. Prevention of relapse in pediatric patients with acute leukemias and MDS after allogeneic SCT by early immunotherapy initiated on the basis of increasing mixed chimerism: a single center experience of 12 children. Leukemia 1999; 13: 2079−2086. \| PubMed \| ChemPort \|
31.	Bader P, Kreyenberg H & Hoelle W et al. Increasing mixed chimerism defines a high-risk group of childhood acute myelogenous leukemia patients after allogeneic stem cell transplantation where pre-emptive immunotherapy may be effective. Bone Marrow Transplant 2004; 33: 815−821. \| Article \| PubMed \| ChemPort \|
32.	Woodard P, Cunningham JM & Benaim E et al. Effective donor lymphohematopoietic reconstitution after haploidentical CD34+-selected hematopoietic stem cell transplantation in children with refractory severe aplastic anemia. Bone Marrow Transplant 2004; 33: 411−418. \| Article \| PubMed \| ChemPort \|

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Acknowledgements

We recognize the outstanding care provided by the nurses of the Mildred-Scheel Bone Marrow Transplantation unit of the Medical School, Hannover.

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Allografting