Peripheral blood progenitor cell collection in low-weight children

An alternative procedure to leukapheresis for peripheral hematopoietic progenitor cell collection in very-low-weight children: A single pediatric center experience

BACKGROUND

PBSC collection using a blood cell separator in very low weight patients can be frequently complicated by severe adverse effects and technical difficulties.

MATERIAL AND METHODS

From March 2013 to January 2017, 14 PBSC collections were performed in 12 children weighing less than 10 kg, affected by different solid tumours. PBSC collection was performed with a "homemade" aseptically assembled circuit. The circuit is composed by a 150 mL collection bag connected with a 4 stopcock ramp, perfused with ACD. This circuit allows collection of a specific total blood amount from CVC, depending on CD34⁺ /kg target.

RESULTS

Mean CD34⁺ cell performance per collection was 9.3 × 10⁶ /kg. Tolerance to the procedure was very good as none of the patients experienced complications, with the exception of a patient who showed mild cyanosis and pallor after collection. Moreover, no bleeding or thrombotic complications have been observed. To date, 16 PBSC reinfusions have been performed in 7 children with a mean CD34⁺ cells viability of 98.1% ± 2.7 and mean WBC viability of 57% ± 10. Cell recovery after thawing was 87% ± 10.8. A rapid graft intake for both neutrophils and platelets, between day 7 and 20 after reinfusion was observed.

DISCUSSION

The procedure of total blood collection without the use of a cell separator is feasible and allows a good PBSC collection without significant side effects in very low-weight children. Moreover, this method could represent a valid and safe alternative to leukapheresis in patients where classic procedure could be difficult to apply.

Therapeutic apheresis in children: special considerations

The provision of therapeutic apheresis to children is a technically challenging procedure, requiring trained personnel and an understanding of the disease processes that leads to the need for apheresis. Most apheresis protocols are derived from studies in adult patients, even though most studies are of limited sample size. The focus of this review is to highlight the disease processes commonly treated with therapeutic apheresis in children, and to address the technical considerations pertinent to the provision of safe and effective apheresis in the pediatric setting.

Peripheral blood stem cell collection in pediatric patients: feasibility of leukapheresis under anesthesia in uncompliant small children with solid tumors

Leukapheresis demands patient's compliance and adequate vascular accesses, which can require invasive methods in very small children whose treatment protocol includes hemopoietic stem cell collection for myeloablative chemotherapy and stem cell rescue. Since 1998, at the Istituto Nazionale Tumori of Milan, in selected uncompliant small children, the placement of peripheral vascular accesses and leukapheresis have been performed at the same time under general anesthesia. Peripheral venous cannulas were positioned for blood collection, while blood was returned through either peripheral cannulas or mono-lumen central catheters previously installed for chemotherapy. A continuous-flow cell separator was used for leukapheresis. Between 1998 and 2003, 47 children with solid tumors underwent anesthesia for a total of 54 leukaphereses. The patients' age ranged from 12.7 to 93 months (median 30.3) and their weight ranged from 7 to 20 kg (median 14.1). Neither metabolic nor anesthesiological complications were recorded. In 89% of cases, the CD 34(+) cell target was achieved at a single harvest; the median number of CD 34(+) cells was 10.8 x 10(6)/kg/leukapheresis (range 1-117) and the median collection efficiency was 63.4% (range 25-100.6). Leukapheresis under anesthesia is feasible and safe in very low-weight children whose compliance is lacking due to age and disease.

Safety and efficacy of allogeneic PBSC collection in normal pediatric donors: The Pediatric Blood and Marrow Transplant Consortium Experience (PBMTC) 1996–2003

The use of peripheral blood stem cells (PBSC) for allogeneic transplants in adults has greatly increased. This trend is reflected in pediatrics, where healthy children increasingly are donating PBSC or donor lymphocyte infusion (DLI) via apheresis for use by ill siblings. There is a potential concern that the risks of PBSC collection may differ for pediatric donors. However, no large studies have assessed safety issues in this population. To address this need, we reviewed 218 (213 PBSC, five DLI) collections in 201 normal pediatric donors (8 months to 17 years, median 11.8 years) at 22 institutions in the Pediatric Blood and Marrow Transplant Consortium. Donors received a median of 4 days of growth factor, and mean collection yield was 9.1 x 10(6) CD34+ cells/kg recipient weight. Younger age, days of apheresis, and male gender predicted increased yield of CD34+ cells/kg donor weight. Growth factor-induced pain was mild and reported in less than 15% of patients. Most donors <20 kg (23/25, 92%) required PRBC priming of the apheresis machine. This experience with over 200 collections demonstrates that PBSC collection is safe in normal pediatric donors and desired CD34 cell yields are easily achieved. Younger children utilize more medical resources and children <20 kg usually require a single blood product exposure.

Analysis of factors affecting PBPC collection in low-weight children with malignant disorders

BACKGROUND

PBPC collection in children weighing </=25 kg is hampered by technical and clinical problems related to vascular access, low total blood volume, anticoagulation, side effects, and psychological impact. The aim of this study was to analyze several clinical and technical factors, other than pre-apheresis CD34(+) count, that may affect PBPC collection in these low-weight children.

METHODS

Data from 88 leukaphereses performed in 45 children were analyzed, including pre-apheresis CD34(+) cell count, COBE Spectra software (version 4.7 versus 6.0), apheresis volume [standard versus large-volume leukapheresis (LVL)] and patient's diagnosis, age, weight and sex.

RESULTS

The median number of PBPC collected was 6.68 mononuclear cells (MNC)x10(8)/kg (range 2.36-19.05) and 1.69 CD34(+) cellsx10(6)/kg (range 0.08-13.79). Multivariate analysis showed that factors independently associated with the CD34(+) cell yield per apheresis were pre-apheresis CD34(+) cell count (P<0.001), diagnosis (P=0.008) and apheresis volume (P=0.009). Recruitment of CD34(+) cells was also independently affected by the apheresis volume, being higher in the LVL group (P=0.008).

DISCUSSION

We have demonstrated that, apart from the well-known influence of the pre-apheresis CD34(+) cell count, two other factors have a major impact on the CD34(+) cell yield: patient's diagnosis and apheresis volume. In addition, taking into account that side effects were mild and tolerable, we have confirmed that LVL is a safe and effective procedure in children </=25 kg, and that AutoPBSC software could be reliably used in these patients, provided that an experienced team performs the procedure.