HPC collection in children is an efficient and well tolerated technique, performed as an outpatient procedure. With the new mobilization schemes and leukapheresis technology, we can collect a high number of HPC allowing pediatric oncologist to establish more aggressive chemotherapy protocols hoping to improve patient outcome.

Aim: Mesenchymal stromal cells (MSC) are a promising tool for cellular therapy and regenerative medicine. One major difficulty in establishing a MSC expansion protocol is the large volume of bone marrow (BM) required. We studied whether cells trapped within a collection bag and filter system could be considered as a source of MSC. Results: From the 20 BM collection bag and filter systems, we recovered an average of 1.68 × 108 mononuclear cells, which is the equivalent to 60 ml of filtered BM. Mononuclear cells were expanded ex vivo to 17 × 106 MSC, with purity shown by a CD44+, CD105+, CD90+ and CD73+ immunophenotype, a reduction of 20% proliferating cells in a mixed lymphocyte reaction and also the ability of adipocyte differentiation. Conclusion: Long-term MSC cultures were established from the usually discarded BM collection bag and filter, maintaining an appropriate phenotype and function, being suitable for both investigation and clinical settings.

Background Hematopoietic stem cell transplantation is used in the treatment of children with malignant and non‐malignant diseases. However, apheresis of peripheral blood stem cells (PBSC) represents a challenge in children below 10 kg. Methods A retrospective trial was conducted in the Cellular Therapy Department of Portuguese Oncology Institute of Porto. Inclusion criteria: children with body weight inferior to 10 kg who underwent autologous PBSC apheresis until 2021. Demographic and clinical data were collected and our institutional protocol was described. COBE Spectra apheresis system (TerumoBCT, Lakewood, Colorado) until 2012 and then Spectra Optia (TerumoBCT) were used. Results Sixteen leukocytaphereses were performed in 13 patients—nine females (69%). Mean age and weight were 13.31 months (±5.26) and 8.31 kg (±1.17), respectively. The initial CD34+ cells/μL in peripheral blood was 70.8 (±61.9). A central venous catheter (CVC) was exclusively used in all but one patient, in whom a peripheral vein was also required. In 10 procedures, both heparin and anticoagulant citrate dextrose solution—formula A (ACD‐A) were used; in the remaining ones, only ACD‐A was employed. The median duration of each procedure was 168 minutes (±45) and 2.96 blood volumes (±0.31) were processed. Median CD34+ cells yield per leukocytapheresis was 6.52 × 106/kg (±9.87 × 106). CD34+ cell extraction rates were not significantly different between the two apheresis systems. Platelet and magnesium levels were significantly lower after collection (P < .001 and P = .009, respectively). Conclusions Although recommendations are lacking, we have successfully and safely performed leukocytaphereses in children with body weight below 10 kg. The authors believe that a permanent and dynamic comprehensive evaluation of each child is paramount for attaining good results.

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