Successful large volume leukapheresis on a small infant allogeneic donor

Collection of hematopoietic stem cells and immune effector cells in small children

Apheresis procedures are standard of care for a wide range of indications in children, collection of hematopoietic stem cells being the most frequent one. With increasing numbers of hematopoietic stem cell transplants, advances in graft manipulation techniques and the development of innovative therapies using immune effector cells and gene therapy, apheresis within the pediatric population is growing in demand. While young children have higher circulating white blood cell counts and robustly mobilize hematopoietic stem cells, apheresis machines were designed for use within the adult population and apheresis procedures in children, particularly small children, can be more challenging as vascular access, collection techniques and impact of extracorporeal volumes increase the rate of adverse events. In this article we review topics of particular relevance to hematopoietic stem cell and immune effector cell collections in small children.

Immediate and long-term somatic effects, and health-related quality of life of BM donation during early childhood. A single-center report in 210 pediatric donors

Since 1968, when Leiden undertook the first successful European pediatric BM transplantation with a 7-year-old sibling donor, more than 300 young children have donated BM in our unit. We first retrospectively studied a cohort of 210 donors, younger than 13 years at donation, to survey procedures of donor eligibility and study immediate effects of BM donation. We then performed a long-term follow-up (FU) and health-related quality of life (HRQoL) study. Despite documentation of previous medical conditions, no child was declared unfit to donate. We found that iron deficiency anemia or low-iron stores in BM did not result in treatment or extended FU. Harvest volumes exceeded 15 mL/kg in 65% of donors, with more than half requiring allogeneic blood transfusions. Donors had no structured FU after their first post-donation control. In this study, 25% of donors reported at least one somatic complaint at long-term FU. Finally long-term HRQoL revealed high scores in most subdomains (representing a higher QoL), compared to norm groups. These results indicate the need for development of (inter)national guidelines for pediatric stem cell donor care management.

World apheresis registry data from 2003 to 2007, the pediatric and adolescent side of the registry

OBJECTIVES

Paediatric patients are a special group in apheresis. It is general accepted to use adult indications in paediatric patients, but data in this age group are rare. In order to provide more information of apheresis practise in children and young adults (<21a) we will report of knowledge learnt by data from the registry from 2003 until 2007.

METHODS

This is a web-based registry. A link is available from the WAA homepage (www.worldapheresis.org). So far data from 12,448 procedures have been included. Six hundred and twelve procedures were performed in 135 children and young adults (308 procedures<16a, 237 from 17 to 20a, and 67 with 21a) representing 5% of the total population. The median age was 14 years (range 1-21 years), 74 male and 61 female. These data were entered by 15 centres with a frequency of in median 18 aphereses in young patients per centre (range 1-287) from 2003 to 2007.

RESULTS

Main indications: haematological diseases and also nephrological, and neurological. The type of aphereses was mainly Leukapheresis (196, 33%), plasma exchange (149, 25%), photopheresis (127, 21%), and lipid aphereses (79, 13%). Blood access: peripheral vessels in 305 procedures (50%, compared to 73% in adults), central venous catheter in 239 (38%), and AV-fistula in 2% and 0.3%, and in 8 (1.31%) procedures an arterial line was used. Anticoagulation was mostly by ACD (71%), heparin (18% or the combination of both (3%). 39 adverse events (AE) were registered in 22 (=3.59%) of the procedures, mostly graded as mild. Treatment was interrupted in 14 procedures (2.29%). AE's were abdominal pain, anaphylactic shock, flush, hyper- and hypotension, nausea, vertigo, cephalea and need for sedation and technical problems with the device and problems with the venous access. The rate of AE's was similar for stem cell harvesting and for plasma exchange (4% and 4.7%, respectively).

CONCLUSION

The paediatric data compared to the whole registry data set are showing that aphereses are performed as safe in paediatrics as in adults. Centres are mostly handling only a few cases younger than 21. Therefore more exchange of information and experience in paediatric apheresis is warranted.

Risks and methods for peripheral blood progenitor cell collection in small children

Peripheral blood progenitor cells (PBPC) are increasingly used as a source of stem cells for either autologous or allogeneic hematopoietic transplantation in children. Although technically similar to adult procedures, apheresis in small children worries some operators and physicians that have little experience in managing pediatric patients or donors. However several published series have showed that these procedures, when performed by experienced teams are safe and can obtain enough amount of PBPC for either autologous or allogeneic hematopoietic transplantation. Some technical aspects must be considered in pediatric apheresis due to the size of the patient/donor. Factors that must be evaluated are extracorporeal circuit volume, blood flow rates, type of anticoagulant and vascular access. Other important issue to be considered is the emotional stress for them and their relatives. Leukaphereses in children may be performed with any of the reported continuous blood cell separator without sedation. Adverse events are mainly related either to vascular access or to metabolic or hemodynamic changes. Anyway, taking all these complications together, they are not higher than those adverse events or toxicities reported after general anesthesia and bone marrow harvesting.

Autologous peripheral blood stem cell collections in children weighing less than 10 Kg with solid tumors: Experience of a single center

There have only been a few reports and limited performance of peripheral blood stem cell (PBSC) collection in very small children weighing less than 10 kg. In this study, we intended to evaluate the safety and yield of PBSC collection, with the efficacy of PBSC transplantation (PBSCT) in the smallest children with solid tumors. From January 1998 to February 2004, 173 children underwent PBSC collection in Samsung Medical Center, Korea. Of these, 15 (8.7%) children weighed less than 10 kg and their clinical diagnoses were neuroblastoma (10 cases), rhabdoid tumor (2 cases), rhabdomyosarcoma (2 cases), and Wilms tumor (1 case). PBSCs were collected following chemotherapy plus G-CSF mobilization. The median age and weight at the time of apheresis were 15 months and 9 kg, respectively. The median number of PBSC collection procedures per case was 4 (range, 2-7). The median cell yield per apheresis product was 0.95 (range, 0.01-33.32) x 10(6)/kg CD34+ cells and 1.96 (range, 0.12-23.39) x 10(8)/kg mononuclear cells. No complications associated with citrate toxicity and other adverse effect were observed during the procedures. After high-dose chemotherapy, 14 patients were reinfused with PBSCs alone and all showed successful hematopoietic recovery. We concluded that PBSC collection would be a safe and practical procedure, even when done in the smallest children, provided that adequate intravascular fluid volume and circulating red cell mass were maintained. Also, the use of PBSCs to support high-dose chemotherapy was well tolerated and might enhance hematological recovery in the smallest children showing the excellent efficacy of PBSCT.

Pediatric large-volume leukapheresis: a single institution experience with heparin versus citrate-based anticoagulant regimens

BACKGROUND

Anticoagulant-associated toxicity may exert significant effects on the safety and efficacy of large-volume leukapheresis (LVL) in children, however, few studies specifically address management of this issue.

STUDY DESIGN AND METHODS

Seventy-four consecutive LVL procedures (mean, 4 blood volumes processed) in children weighing less than or equal to 30 kg (minimum, 10.9 kg) were analyzed. The first 21 procedures were evaluated retrospectively; 11 used heparin alone (Group I) and 10 used heparin plus reduced-dose ACD-A (whole blood to anticoagulant ratio > or =20:1) (Group II). The next 53 procedures were evaluated prospectively and used full-dose ACD-A (whole blood to anticoagulant ratio < or =13:1), intravenous divalent cation prophylaxis and no heparin; 11 used calcium alone (Group III) followed by 42 with calcium plus magnesium (Group IV).

RESULTS

Seventy-four LVL (56 PBPC and 18 MNC) collections were performed in 38 subjects. One donor in Group I experienced a significant groin hematoma at the site of line placement. One donor each in Groups III and IV had mild paresthesias. Despite a mean citrate infusion rate of 2.6 mg per kg per minute, mean postapheresis serum potassium and ionized magnesium and calcium concentrations in Group IV declined by only 9, 8, and 4 percent, respectively, and stable levels of these variables were maintained 24 hours later. Postapheresis PLT counts declined significantly from baseline preapheresis levels in all groups (mean, 52% decrease).

CONCLUSIONS

Use of full-dose citrate anticoagulant with prophylactic intravenous divalent cation infusion offers an effective and safe approach to management of anticoagulant-related toxicity in children undergoing LVL.

Peripheral blood progenitor cell collection in low-weight children

Peripheral blood progenitor cells (PBPC) are substituting bone marrow as a source of stem cells for either autologous or allogeneic hematopoietic transplantation. Several papers have been published on the experience of various groups in their mobilization and transplantation in children. Some technical problems have derived from the size of the patient or donor in the pediatric setting. Thereby, there is some concern regarding leukapheresis in very small children (weighing less than 15-20 kg). This paper summarizes our own data and that of other groups for the mobilization and collection of PBPC in the smallest children. Data from the literature show that mobilization with cytokines alone or in combination with chemotherapy is well tolerated by these patients. Pediatric donors may be used for allogeneic transplantation with no higher incidence of complications. PBPC collection even in the smallest children is a safe and efficient procedure when performed by experienced apheresis teams.

Technique for PBSC harvesting in children of weight under 10 kg

Peripheral blood stem cell (PBSC) harvesting in the smallest children (weight <10 kg) using separators is complicated by specific problems. The volume of the separation set exceeds 25% of the total blood volume and the vascular access is generally not sufficient. Therefore, a simple manual technique for PBSC harvesting was developed. Three children (6-9 kg), with newly diagnosed tumours were scheduled to be treated with three to six sequential courses of high-dose chemotherapy, each followed by PBSC support. PBSC harvests were started after mobilization using cyclophosphamide and G-CSF when the peripheral blood CD34+ cell count exceeded 50/microl. About 50 ml of blood was drawn from a venous catheter, injected into a transfer bag containing ACD-A, and centrifuged. The buffy coat obtained was pooled in a collection bag, remaining plasma and erythrocytes were immediately reinfused and a subsequent cycle started. From three to 13 cycles were performed in 1-3 days and 18.0-32.2 x 10(6) CD34+cells/kg were collected. We did not detect any bacterial contamination or any notable complications. Fifteen PBSC reinfusions have been performed to date, each with rapid engraftment taking between 7 and 13 days. Patients are in very good PR (18 months from diagnosis) or in CR (6 and 8 months). We can conclude that this procedure is feasible and safe.