Successful large volume leukapheresis on a small infant allogeneic donor

Article metrics

Abstract

We successfully performed a hematopoietic stem cell apheresis on the smallest allogeneic donor reported to date, a 6.1 kg female. After placement of a dialysis catheter in the left femoral vein, the COBE Spectra was primed with one unit of paternal whole blood. Heparin and anticoagulant citrate dextrose, solution A (ACD-A) were slowly administered to the patient. Ionized calcium levels were checked hourly and calcium gluconate was given for hypocalcemia. Coagulation parameters were checked throughout the procedure. We collected 4.4 × 106 CD34+ cells/kg (recipient). The donor tolerated the procedure well and was discharged the following day. Five months later, the child manifests no obvious late effects. Bone Marrow Transplantation (2000) 26, 339–341.

Case study

A 6.1 kg, 7-month-old female was identified as an HLA-identical donor for her 2-year-old brother with acute myelocytic leukemia (M5a). The patient with leukemia was enrolled on Children's Cancer Group protocol 2961 and stem cell transplantation is indicated for patients with HLA-matched sibling donors in first remission. Therefore, the baby was selected as the donor. The parents were informed of the possible risks of a leukapheresis procedure. After careful consideration, they gave written consent and wished to proceed with apheresis instead of subjecting her to a bone marrow harvesting procedure. The apheresis procedure itself is not part of an experimental protocol but our institution's standard operating procedures for children undergoing apheresis are followed. Four days before the scheduled date, the donor was given daily subcutaneous G-CSF, 10 μg/kg/day (Neupogen; Amgen, Thousand Oaks, CA, USA) to mobilize the CD34+ cells.

Due to the small size of the donor, a very slow flow rate of blood through the COBE Spectra (Lakewood, CO, USA) was anticipated and platelet clumping was predicted. This would have complicated the collection. Therefore, on the evening prior to the apheresis, 80 mg of aspirin was give to the baby to minimize the possibility of platelet clumping during the procedure. We informed the family that the child was at additional risk for bleeding, since heparin would be used during the apheresis procedure. However, we did not believe that a single dose of aspirin given the night before the procedure would result in anything other than bleeding at the catheter insertion site during apheresis.

On 15 February 1999, the baby was taken to the operating room for placement of a double lumen dialysis catheter. General anesthesia was used for the procedure. An initial attempt was made at cannulizing the right femoral vein, but the catheter could not be advanced. The left femoral vein was accessed percutaneously and a 7-french double lumen dialysis catheter (Bard, Covington, GA, USA) was successfully advanced. Adequate blood return was achieved from both ports, which were each then flushed with heparinized saline, capped and clamped. In order to immobilize the leg for the leukapheresis procedure, a posterior plaster splint was placed from ankle to buttocks. Occlusive dressings were placed over the catheter and puncture sites to prevent contamination from urine and stool. Diapers were changed hourly.

The donor was taken to the pediatric intensive care unit (PICU) for close monitoring because of her small size. Lorazepam and acetominophen were each given only once for agitation or pain. Prior to the procedure, the donor's hemogram revealed: Hgb 10.5 g/dl; platelets 319 × 109/l; WBC 28.8 × 109/l. Immediately prior to starting the apheresis, the donor was premedicated with 80 mg acetaminophen orally and 6 mg diphenhydramine intravenously. Paternal whole blood was used to prime the COBE Spectra. Both father and daughter were type O, Rh positive and CMV negative. AABB standards were followed for serological testing of the father's blood. This unit of irradiated blood (2000 cGy) was used to establish an interface, so that when the donor's blood entered the machine, there would be no delay prior to establishing an interface. When the COBE Spectra was fully primed and ‘Quickstart’ was completed, the donor was bolused with 50 units/kg of heparin. The lines were then connected to the donor. The anticoagulant (AC) of choice with the apheresis run was ACD-A with heparin added (900 units/500 ml bag of ACD-A). This was used to reduce platelet clumping and clotting that may occur due to the slow infusion rate of the citrate anticoagulant. While running at an AC ratio of 1:16, platelet clumps were noted in the ‘collect’ line and therefore the AC ratio was decreased to 1:14, and the citrate infusion rate was 1.2 ml/min/l. At this same time, the donor began to exhibit moderate agitation, tachycardia, and vomiting. This is a well-known citrate reaction, and the procedure was temporarily stopped. An ionized calcium level was drawn and was found to be 0.98 mmol/l (normal >1.0 mmol/l). A bolus of calcium gluconate was given (600 mg over 20 min), and the procedure was resumed after the donor seemed more comfortable. To stabilize the donor's ionized calcium level, a maintenance calcium drip was started. Subsequent ionized calcium levels were normal.

Midway through the procedure, the prothrombin time was 11.2 s (normal 9.6–11.4 s), the activated partial thromboplastin time was 45 s (normal 25–33 s), and the heparin level (anti-Factor Xa) was 0.14 U/ml (normal 0.3–0.7 U/ml). The AC ratio was increased to 1:15 after disappearance of platelet clumps, then increased to 1:16 after heparin assay as it was determined that sufficient anticoagulation had been achieved. By the end of the procedure, the ratio was increased to 1:17.

After nearly 6 h of apheresis run time, 2972 ml of the donor's blood had been processed. Apheresis was started and stopped several times because of slow flow rates, loss of interface and administration of medications to the donor. In total, approximately six times the donor's blood volume (500 ml) was processed. The total volume of the product was 220 ml. After calculating the WBC count, it was determined that we had achieved an adequate collection. The final actual values of the product were: 128 × 108 hematopoetic progenitor cells; 4.4 × 106 CD34+ cells/kg; 130.56 × 104/kg CFU-GM; 130.56 × 104/kg BFU-E (all values based on recipient weight of 11 kg). The contents of the blood warmer (approximately 30 ml whole blood and saline) were rinsed back to the patient, while the residual blood still remaining in the machine was discarded. Heparin was then used to flush the femoral catheter. The donor's platelet count was 65 000, and she was given a 95 ml aliquot of single donor platelets because of oozing around the catheter site. The femoral catheter was removed the following day, and she was discharged home in good condition. Although this donor was managed in the PICU, the use of these facilities was merely precautionary, as she tolerated the procedure well.

She was given ferrous sulfate orally for 3 months and achieved stabilization of her hemoglobin. She developed no infections at her catheter insertion sites nor did she ever have clinical evidence of venous thrombosis. At her checkup at 1 year of age, she had a normal hemogram. At 17 months of age, she is developmentally normal and doing very well.

Discussion

This 6.1 kg normal infant donor is the smallest child reported to date to undergo a leukapheresis procedure for donation of allogeneic stem cells. She was an ideal donor for her 2-year-old, 11 kg brother who was in first remission from his recently diagnosed acute myelocytic leukemia. The donor's brother was enrolled in Children's Cancer Group Study 2961 (Treatment of Children with Acute Myelogenous Leukemia), and a hematopoietic stem cell transplant is recommended when an HLA-matched family donor can be identified.

Others have previously reported their experience with young children who served as autologous stem cell donors,123456 with only one citation focusing on pediatric allogeneic donors.7 We believe our normal donor is the smallest child reported to date to have undergone an apheresis procedure. There were several risk factors that were inherent in the procedure including the line placement, G-CSF priming, hemorrhage, infection, thrombus formation, exposure to blood products, anesthesia and citrate toxicity. In addition, mechanical apheresis problems such as platelet clumping, clotting or inability to establish an interface and collect the cells could have occurred. However, administering aspirin to inhibit platelet function, titrating anticoagulants and carefully monitoring the procedure enabled us to overcome these obstacles.

The problems with low flow rate of the COBE pump were addressed using several measures. The lower limit of the inlet pump is 20 ml/min and the lower limit of the AC and collect/replace pumps is 1.0 ml/min. The desired AC infusion rate for this procedure was to be less than or equal to 1.0 ml/min/l. Due to this low infusion rate, platelet clumping is an obvious concern. This was circumvented by the combination of aspirin, heparin and ACD-A mixture. Close monitoring of coagulation parameters, including heparin assay, enabled us to accurately regulate AC, heparin and calcium infusions.

With appropriate collaboration between the transplant and the apheresis teams, an adequate amount of hematopoietic stem cells was successfully harvested and donated to the patient's 2-year-old brother, who is now 300 days from transplant and in continuous complete remission without evidence of graft-versus-host disease. The patient, who was conditioned with i.v. busulfan and cyclophosphamide, had an absolute neutrophil count of more than 500/μl on T + 9. He was noted to have a stable platelet count above 20000/μl on T + 12 and received only one red cell transfusion during the entire transplantation process.

This apheresis procedure may pose more potential risks for the donor than would a bone marrow harvest. The ethical considerations of hematopoietic stem cell collections from donors who are minors will clearly be debated whenever very small children are involved. Although the apheresis procedure seems to be safe and well tolerated, a prospective multi-center study is needed to assess the safety profile of leukapheresis in our smallest donors. Future studies will determine if peripheral blood stem cells are superior to bone marrow as the stem cell source for pediatric patients undergoing allogeneic transplantation. Issues of engraftment, acute graft-versus-host disease, chronic graft-versus-host disease and survival need to be considered when there is a choice of stem cell source. At this time, no definitive data exist to make this decision. In our institution, we have elected to use peripheral blood stem cells instead of bone marrow whenever possible. In our experience, engraftment occurs earlier, fewer transfusions are needed and hospital stay is shorter when peripheral blood stem cells are used instead of bone marrow. For these reasons, peripheral blood stem cells were used for transplantation in our patient. Future studies will need to extensively collect data on complications of apheresis procedures in small children. At this time, there are insufficient data to suggest that donor safety is improved when peripheral blood stem cell collections are used in lieu of bone marrow-derived stem cells. Clearly, apheresis procedures are less painful and recovery is quicker. However, long-term effects resulting from apheresis of normal, young donors require study.

References

  1. 1

    Kanold J, Halle P, Berger M et al. Large-volume leukapheresis procedure for peripheral blood progenitor cell collection in children weighing 15kg or less: efficacy and safety evaluation Med Pediatr Oncol 1999 32: 7–10

  2. 2

    Berger M, Kanold J, Rapatel C et al. Feasibility of a PB CD34+ cell transplantation procedure using standard leukapheresis products in very small children Bone Marrow Transplant 1997 20: 191–198

  3. 3

    Takaue Y, Kawano Y, Abe T et al. Collection and transplantation of peripheral blood stem cells in very small children weighing 20kg or less Blood 1995 86: 372–380

  4. 4

    Nussbaumer W, Schonitzer D, Trieb T et al. Peripheral blood stem cell (PBSC) collection in extremely low-weight infants Bone Marrow Transplant 1996 18: 15–17

  5. 5

    Diaz M, Alegre A, Benito A et al. Peripheral blood progenitor cell collection by large-volume leukapheresis in low-weight children J Hematother 1998 7: 63–68

  6. 6

    Marson P, Petris M, De Silvestro G . Collection of peripheral blood stem cells in pediatric patients: a concise review on technical aspects Bone Marrow Transplant 1998 22: (Suppl. 5) S7–S11

  7. 7

    Gonzalez M, Benito A, Diaz M et al. Peripheral blood progenitor cell (PBPC) collection by large-volume leukapheresis from pediatric donors Bone Marrow Transplant 1999 23: 631–632

Download references

Author information

Correspondence to M Nieder.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Pahys, J., Fisher, V., Carneval, M. et al. Successful large volume leukapheresis on a small infant allogeneic donor. Bone Marrow Transplant 26, 339–341 (2000) doi:10.1038/sj.bmt.1702482

Download citation

Keywords

  • leukapheresis
  • infant
  • allogeneic donor

Further reading