A minimal dose of unmanipulated bone marrow infusion without conditioning for T-B+NK- severe combined immunodeficiency

Hematopoietic stem cell transplantation (HSCT) is the standard method of reconstituting immune function in severe combined immunodeficiency (SCID); however, there is no consensus about optimal cell doses. In this study, we investigated HSCT outcomes and immune reconstitution, following minimal dose (MD) HSCT in T cell-negative (T-), B cell-positive (B+), natural killer cell-negative (NK-) SCID patients. We retrospectively reviewed patients with SCID who received HSCT between 2002–2018. Standard dose (SD) and MD were classified based on a total nucleated cell count (TNC) of 1.0 × 108/kg or more and less. Total seven patients with SCID received HSCT. MD group (n = 4) were administered 5 mL or less of bone marrow without conditioning, with median TNC and CD34+ cell counts of 0.49 × 108/kg and 0.62 × 106/kg, respectively. T cells recovered within a year, and immunoglobulin supplementation was discontinued at median 3.5 months after HSCT in all MD recipients. All MD recipients were alive without disease recurrence at a median of 126.9 months after HSCT, exhibiting donor chimerism in the range of 10.1–100%. In patients with T-B + NK- SCID, sufficient therapeutic effects were safely obtained with minimal dose of bone marrow infusion without conditioning.

A minimal dose of unmanipulated bone marrow infusion without conditioning for T-B+NK- severe combined immunodeficiency

Purpose Hematopoietic stem cell transplantation (HSCT) is the standard method of reconstituting immune function in severe combined immunodeficiency (SCID); however, current conditioning recommendations and optimal cell doses lack consensus. In this study, we investigated HSCT outcomes and immune reconstitution, following minimal dose (MD) HSCT in T cell-negative (T-), B cell-positive (B+), natural killer-cell negative (NK-) SCID patients. Methods We retrospectively reviewed patients with SCID who received HSCT between 2002–2018. Standard dose (SD) and MD were classified based on a total nucleated cell count (TNC) of 1.0 × 10 8 /kg or more and less. Results Seven patients with SCID received HSCT, of which four belonged to the MD group. Patients in the MD group were administered 5 mL or less of bone marrow without conditioning, with median TNC and CD34+ cell counts of 0.49 × 10 8 /kg and 0.62 × 10 6 /kg, respectively. T cells recovered within a year after HSCT, and immunoglobulin supplementation was discontinued at a median of 3.5 months after HSCT in all MD recipients. All MD recipients were alive without disease recurrence at a median of 126.9 months after HSCT, exhibiting donor chimerism in the range of 10.1%–100%. Although grade II–III graft-versus-host diseases occurred, these were manageable in all patients. One of the three patients in the SD group died of cytomegalovirus infection, while another was dependent on intravenous immunoglobulin until 41 months after HSCT. Conclusion In patients with T-B+NK- SCID, sufficient therapeutic effects were safely obtained with minimal dose of bone marrow infusion without conditioning.

COPING WITH THE COVID19 PANDEMIC IN A HEMATOLOGY, TRANSPLANTATION AND CELL THERAPY UNIT IN SOUTHERN BRAZlL

We started 2020 with perspectives that quickly changed in March when the SARS-Cov-2 pandemic started in Brazil. Our center has a unit, called the Protected Environment with 30 beds with HEPA filters where malignant disease, autologous and allogeneic transplants are performed. In March 2020, the contingency plan designed since January to deal with COVID 19 pandemic of Porto Alegre Clinicas Hospital (HCPA) began highly restricting visits, consultations and elective procedures. Our challenge was to maintain the best care for our patients and healthcare professional’s safety. We suspend all visits and reduce relative patients’ companies to only essential. Our team was already one with the highest percentage of hand washing in the hospital, intensified infection control measures and implemented new individual protection equipment surgical masks and face shields. We started a new way to inform family members using digital platforms and improved the Wi-Fi network inside the unit to maintain patient external contact and reduce their loneliness. All Professional meetings and rounds became virtual.1,2,3 When the first cases started in Porto Alegre, we had already implemented and validated the performance of the PCR for SARS-COV-2, with result until 24 hours. So, we could organize the flow of patients for hospitalizations avoiding admissions of Covid asymptomatic patients. HealthCare’s with any symptoms were kept away from work and quickly tested. We followed the guidance of the Brazilian society of BMT and started to perform only urgent transplants, greatly reducing the number of autologous transplants performed. All patients candidates stem cell transplant were instructed to maintain isolation for 14 days before admission and collected PCR 24 hours before admission. Related and unrelated bone marrow donors underwent clinical screening and PCR testing 24 hours before collection and the marrow was cryopreserved until results what changed our routine marrow infusion and sometime modified the collection from marrow to peripheral Hematopoietic stem cell in order to obtain adequate cellularity.1,2,3 Despite all the difficulties and challenges the Covid pandemic imposed upon us, we managed to perform 16 Transplants from March to September, between autologous and allogeneic and we had no cases of covid transmission inside deaths related to COVID until now. All patients who had COVID19 or tested positive to SarsCov2 were outpatients, either from the Day Hospital or the outpatient clinic and had complete resolution of the condition.

In-Vivo Adsorption of Iso-Haemagglutinin (IHA) Antibodies By Donor Type Red Cell Transfusion during Conditioning Is a Safe and Effective Method to Overcome Major ABO Incompatibility-Related Acute Hemolytic Reactions in Stem Cell Transplant Using Bone Marrow As Stem Cell Graft Source

Introduction: ABO blood group incompatibility is not a barrier to performing allogeneic stem cell transplant, but may result in life-threatening acute hemolytic reactions as well as pure red cell aplasia. As stem cell product manipulation is cumbersome and may entail cell loss, attempts have been made in the past to reduce IHA titers in-vivo either by donor type red cell transfusion or using frozen plasma in peripheral blood stem cell (PBSC) transplants (Scholl et al. Transfusion 2005; Damodar et al. BMT 2005). The efficacy of such strategies have not been described in Bone marrow transplant (BMT) setting. We are reporting the effectiveness and safety of donor type red cell infusion during conditioning as a method of reducing acute hemolytic reaction during transplant while using unmanipulated marrow as stem cell source (BMT). Materials and Methods: We retrospectively analyzed 241 consecutive allogeneic BMTs for beta thalassemia major, between August 2015 and July 2019 out of which 82 were ABO mismatched transplants, either major (n=30) or minor (n=40), or bidirectional (n =12) mismatched. Infusion of donor type red blood cell during conditioning after the infusion of Anti-thymocyte globulin (ATG) and post-transplant complication of acute hemolysis were determined by retrospective review of individual medical records. When there is a major ABO incompatibility and IHA titers against the donor were > 1:64, a single unit of donor type Packed Red Blood cell (PRBC) was divided into 4 aliquots, irradiated and administered over 4 days at increasing incremental volumes once daily over 4 days if tolerated (Day 1 - 5 ml, Day 2 - 10ml, Day 3- 20-30 ml, Day 4 - 40-60 ml) (Fig.1). Patients were watched carefully for febrile reactions and hemoglobinuria and mild reactions were tolerated. If no clinical evidence of severe hemolytic reaction, bone marrow was infused without manipulation on the day of transplant. Results: Out of 30 patients with major ABO incompatibility, 13 patients had titers more than 1:64 (highest was 1:2048) and hence received donor type PRBC infusion in small incremental doses. Eight patients showed evidence of some hemolysis (4 during infusion of donor type PRBC aliquot and 4 showed increase in indirect bilirubin with marrow infusion) which was managed conservatively with hydration. None of the patients developed severe hemolytic or anaphylactic reaction at the time of marrow infusion. Post infusion of donor type blood, titers were checked in 7 patients. 6 patients had significant reduction in titers (all were less than 1:32) except for 1(titers increased to 1:4096), which was not considered clinically relevant as he tolerated 100mls of donor type PRBC. He also tolerated marrow infusion without any evidence of severe hemolytic reaction. Four more patients with bidirectional mismatch had IHA titers against the donor more than 1:64, hence the same procedure was followed. One of them had mild hemoglobinuria during donor type PRBC infusion and 3 patients had mild hemoglobinuria with rise in indirect bilirubin at the time of marrow infusion. All patients were managed conservatively with hydration. Conclusion: Our experience demonstrated that donor-type PRBC infusion as a method of in-vivo adsorption of IHA antibodies against donor is safe and effective in preventing acute hemolysis in major ABO-mismatched stem cell transplants even in the context where bone marrow is used as graft source. This simple method in addition to avoiding the problems related to product manipulation can also be safely and easily performed in resource limited settings. Disclosures No relevant conflicts of interest to declare.

Endothelial cell fitness dictates the source of regenerating liver vasculature

Neoangiogenesis plays a key role in diverse pathophysiological conditions, including liver regeneration. Yet, the source of new endothelial cells (ECs) remains elusive. By analyzing the regeneration of the liver vasculature in irradiation-based myeloablative and nonmyeloablative bone marrow transplantation mouse models, we discovered that neoangiogenesis in livers with intact endothelium was solely mediated by proliferation of resident ECs. However, following irradiation-induced EC damage, bone marrow–derived mononuclear cells were recruited and incorporated into the vasculature. Further experiments with direct bone marrow infusion or granulocyte colony–stimulating factor (G-CSF)–mediated progenitor cell mobilization, which resembles clinically relevant stem cell therapy, demonstrated that bone marrow–derived cells did not contribute to the regeneration of liver vasculature after two-thirds partial hepatectomy (PHx). Taken together, the data reconcile many of the discrepancies in the literature and highlight that the cellular source of regenerating endothelium depends on the fitness of the residual vasculature.

From Auto- to Allotransplantation: Immunomodulatory Protocol for Hand and Arm Transplantation

Aim To achieve a favorable risk–benefit balance for hand transplantation, an immunomodulatory protocol was developed in the laboratory and translated to clinical application. Methods Following donor bone marrow infusion into transplant recipients, hand and arm allografts have been maintained on low-dose tacrolimus monotherapy. Results Good-to-excellent functional recovery has been achieved in patients compliant with medication and therapy, thus restoring autonomous and productive lives. Conclusion The risk-benefit balance can be tilted in favor of the hand transplant recipients by using an immunomodulatory protocol with minimum immunosuppression.