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

ABSTRACT 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.

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.

[Husband to wife renal transplantatation and pretransplant HLA immunization: about two cases]. / Transplantation rénale entre époux et immunisation anti-HLA en prégreffe: à propos de deux observations.

Renal transplantation is the best therapeutic approach for end-stage kidney disease. Renal transplantation can be performed using living donors or brain-dead donors. Vaccination in recipients poses a real problem with the transplantation process because it is responsible for particular difficulties in choosing a donor and above all exposes to the risk of transplant rejection. We here report two cases of husband to wife renal transplantation. The recipients had low levels of antibodies against HLA antigens of donors but sex-associated differences in post-transplant results were found. Indeed, HLA immunization after pregnancy is a real obstacle to husband to wife renal transplantation. Despite the low husband-wife HLA matching (unrelated donor), renal transplantation is a good alternative for renal transplantation from brain-dead donors, who are lacking in Morocco.

[Cytotoxicity of natural anti-HLA antibodies in Moroccan patients awaiting for kidney transplantation]. / Cytotoxicité des anticorps anti-HLA naturels chez des patients marocains candidats à la greffe rénale.

The presence of anti-HLA antibodies in the serum of a patient result from an immune response produced during an immunizing event as transfusion, pregnancy or graft. These antibodies can be cytotoxic by activating the complement pathway via C1q and may cause organ rejection during the transplant. Some male patients awaiting kidney transplantation are seropositive for anti-HLA antibodies when they have no immunizing antecedent event. These antibodies are qualified as natural antibodies. Our work is to assess the cytotoxicity of natural anti-HLA antibodies in patients followed at the immunology laboratory of the blood transfusion service and hemovigilance (STSH) as part of the kidney transplant. PATIENTS AND METHODS: We evaluated the cytotoxicity of HLA antibodies detected in male Moroccan patients without immunization history using C1qScreen One Lambda reagent for Luminex™. RESULTS: Non-immunized men were positive for HLA antibodies screening in 25.4%. These antibodies are not cytotoxic. CONCLUSION: Our study showed a positivity rate of natural HLA antibody low than the literature (25.4% against 63%). It appears that these natural antibodies are not cytotoxic and their involvement in renal transplant remains to be determined.

[Serological tests for celiac disease in Moroccan patients with type 1 diabetes]. / Dépistage sérologique de la maladie cœliaque chez des patients marocains atteints de diabète type 1.

Celiac disease (CD) is an autoimmune disease frequently associated with type 1 diabetes (T1D). The prevalence of CD in patients with T1D varies from 3 to 6%. The clinical manifestation of CD in patients with T1D is classified as asymptomatic in about half of cases. Our study aims to determine the frequency of anti-tissue transglutaminase autoantibodies (IgA-tTG) and anti-gliadin antibodies (AGA) in patients with type 1 diabetes in order to early recommend jejunal biopsy and establish a gluten-free diet before the onset of clinical signs and complications of celiac disease. Subjects included in this study were patients with T1D and untreated CD who showed no signs of this disease. The detection of IgG tTG, IgG IgA and IgG AAG was performed using Luminex technology. We enrolled 31 patients. The study involved 16 men and 15 women. IgA AAG were positive in 4(13%) patients and IgG were positive in 7(22,5%) patients. IgA tTG were positive in 3(10%) patients and IgG was positive in one (3%) patient. In our study the association of diabetes type 1 with biomarkers of CD is not uncommon hence the importance of systematic screening for type 1 diabetes. The diagnosis of this atypical and silent CD form is important given the risk of serious complications such as malabsorption and gastrointestinal cancers.