Development of apheresis techniques and equipment designed for patients weighing less than 10 kg

[Pediatric aphereses (workshop SFGM-TC)]

Practice of pediatric aphereses - in particular when caring for low-weight children - differs from the practice of adult aphereses, since pediatric aphereses represent low numbers of procedures, which has practical implications in terms of practical training and retraining for involved healthcare personnel, as needed for habilitation and validation of ongoing competencies. A specific training is mandatory in order to ensure both the child and the staff safety during and after collection, as well as ensure high quality of the collected cell product and that its meets predefined specifications that depend on its intended use. Low and very low-weight children deserve a particular attention for a number of procedural and clinical aspects: the nature and quality of venous accesses to ensure proper operation of the cell separator, management of hemodynamic fluctuations in relation with the relative importance of the extracorporeal blood volume as compared to the total blood volume of the child, risks and clinical manifestations of citrate toxicity, minimization of stress during the procedure that may include but is not limited to pharmacological sedation. The full spectrum of competencies needed to deal with these aspects is rarely present within a single team of healthcare professionals; it most often requires the tight combination of expertise drawing from the collection facility, the pediatric department and possibly the pediatric intensive care unit ward, whether from the same or from different institutions. Interactions must be formalized in a document that accurately describes which category of actors is responsible for each category of acts (prescriptions, decisions), depending on their initial qualifications, specific competencies, and affiliations.

Peripheral blood stem cells collection by apheresis in very low-weight children with malignant diseases-A single center experience

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.

Priming With Red Blood Cells Allows Red Blood Cell Exchange for Sickle Cell Disease in Low-Weight Children

Red blood cell exchanges are frequently used to treat and prevent cerebrovascular complications in patients with sickle cell anemia (SCA). However, the low weight of young children represents serious concerns for this procedure. The Spectra Optia device can perform automatic priming using red blood cells (RBCs) (RCE/RBC-primed) which could allow RBC exchanges (RCE) to be performed in young children without hypovolemic complications, but this method requires evaluation. We prospectively analyzed the clinical safety of the RCE/RBC-primed procedure in 12 SCA low-weight children under either a chronic RCE program or emergency treatment over 65 sessions. We monitored grade 2 adverse events (AEs) such as a decrease in blood pressure, increase in heart rate, fainting sensation, or transfusion reactions and identified the critical times during the sessions in which AEs could occur. Post-apheresis hematocrit (Hct) and a fraction of cell remaining (FCR) values were compared to the expected values. We also compared the impact of automatic RCE (n = 7) vs. RCE/RBC-primed (n = 8) on blood viscosity and RBC rheology. A low incidence of complications was observed in the 65 RCE sessions with only seven episodes of transient grade 2 AEs. Post-apheresis Hct and FCR reached expected values with the RCE/RBC-primed method. Both the automatic and priming procedures improved RBC deformability and decreased the sickling tendency during deoxygenation. Blood rheological features improved in both RCE/RBC-primed and automatic RCE without priming conditions. The RCE/RBC-primed procedure provides blood rheological benefits, and is safe and efficient to treat, notably in young children with SCA in prophylactic programs or curatively when a SCA complication occurs.

Collection, cryopreservation and thawing of stem cells for children weighing less than 25 Kg with high-risk neuroblastoma: A single center results in Morocco

Introduction

An important component of the advances made in neuroblastoma treatment has been the use of peripheral blood stem cells to support high-dose chemotherapy. In this study, we report our experience on a series of small children who have undergone standard and large volume leukaphersis (LVL) procedures, provide an update on a single institution's experience with cryopreservation of autologous peripheral blood stem cells (PBSCs), using 10% dimethyl sulfoxide (DMSO) and applying post-thaw DMSO depletion and analyze a number of variables that may affect viability.

Methods

A total of 36 aphereses were performed on 29 children weighing less than 25 kg between July 2016 and October 2019 at the Ibn Sina university hospital.

Results

Seven females and twenty-two males, median bodyweight 14 kg (9 - 22). A single apheresis was sufficient to obtain at least 3 × 10⁶/kg body weight (BW) of CD34+ cells in 82.8% of the cases. The LVL was performed in 22 aphereses. A median number of 5.9 × 10⁶/kg CD34 cells were collected per apheresis. A total of 60 PBSC samples were cryopreserved and 46 samples were infused. The mean cell viability percentage decreased from 94.75 ± 1.14% before freezing to 70.84 ± 8.6% after thawing (p < 0.001). No correlation was found between post-thaw viability and storage time (r = -0.233; p = 0.234) or number of total nucleated cells (r = 0.344; p = 0.073).

Conclusion

Leukapheresis is safe and feasible in small pediatric patients if the appropriate measures are used. Cryopreservation poses numerous challenges, especially a decrease in cell viability after thawing.

Reduced volume of red blood cell priming is safe for pediatric patients undergoing therapeutic plasma exchange

RATIONAL

Therapeutic Plasma Exchange (TPE) procedures in pediatric patients are challenging due to the large extracorporeal volume of the cell separators, which were designed for adults. Red blood cell (RBC) priming is an alternative for overpassing the risks of hypovolemia, but data referring to the volume of packed RBCs to be infused are yet incomplete. Restricting the volume of RBC priming may potentially be associated with less transfusion reactions.

GOAL

To determine the safety of administering a reduced volume of RBC priming for pediatric patients undergoing TPE, in comparison to the standard volume recommended by the cell separators' manufacturers.

METHODS

This was a case-control study which enrolled 15 pediatric patients undergoing TPE and weighting more than 10Kg. The TPE procedures (n = 406) were divided in two groups: 1) Group1: TPE with ≤150 mL of packed RBC priming and 2) Group2: TPE with 150-250 mL of RBC priming. Groups were compared in terms of hemoglobin / hematocrit and occurrence of adverse reactions.

RESULTS

Group1 and Group2 did not differ significantly in relation to pre- and post-TPE hemoglobin (Hb) levels (p = 0.19 and p = 0.18, respectively). The Δ Hb (Hb pre-TPE - Hb post-TPE) was also not statistically different between the groups. The number of adverse reactions was significantly higher in Group 2 in relation to Group 1 (p = 0.01). The number of allergic reactions was also higher in Group 2 (p = 0.06).

CONCLUSIONS

Restricting the volume of RBC priming to less than 150 mL is safe for pediatric patients weighting more than 10Kg and associated with lower rates of transfusion-related adverse reactions.

Clinical Application of Apheresis in Very Small Dogs Weighing <8 kg to Pediatric Patients

Apheresis in low body weight children and adolescents is challenging due to a variety of technical and clinical issues including vascular access, low total blood volume, and hypotension. Although dogs have been a valuable preclinical model for apheresis, the procedure can be challenging since many pure-bred dogs are extremely small. Therefore, apheresis in these very small breeds presents very similar challenges as seen when performing the procedure in very low body weight people. We describe apheresis of four very small dogs, weighing from 4.6 to 7.6 kg, using either a COBESpectra and Spectra Optia apheresis system (Terumo BCT, Lakewood, CO, USA). Two dogs underwent large volume leukapheresis to collect mononuclear cells in preparation for hematopoietic stem cell transplantation and two dogs underwent therapeutic plasma exchange to treat an immune-mediated disease. In all cases, a dual-lumen hemodialysis catheter placed in the jugular vein provided adequate machine inlet and return flow rates. Machine priming was necessary to maintain hemodynamic stability during the beginning of the procedure, and rinseback was avoided for the same reason. Anticoagulant citrate dextrose solution, solution A was used for the large volume leukapheresis procedures and a combination of anticoagulant citrate dextrose solution, solution A and heparin was used for the therapeutic plasma exchange procedures. As such, serum iCa levels were regularly monitored and 10% calcium gluconate constant rate infusions were used to prevent citrate toxicity. All dogs completed the aphereses with no life-threatening adverse events. We conclude that aphereses in very small dogs is feasible if close attention is paid to hemodynamic stability and citrate toxicity.