Fetal allotransplant recipients are resistant to graft-versus-host disease.

In utero hematopoietic cell transplantation (IUHCT) is an experimental treatment for congenital hemoglobinopathies, including Sickle cell disease and thalassemias. One of the principal advantages of IUHCT is the predisposition of the developing fetus toward immunologic tolerance. This allows for engraftment across immune barriers without immunosuppression and, potentially, decreased susceptibility to graft-versus-host disease (GVHD). We demonstrate fetal resistance to GVHD following T cell-replete allogeneic hematopoietic cell transplantation compared with the neonate. We show that this resistance is associated with elevated fetal serum interleukin-10 conducive to the induction of regulatory T cells (Tregs). Finally, we demonstrate that the adoptive transfer of Tregs from IUHCT recipients to neonates uniformly prevents GVHD, recapitulating the predisposition to tolerance observed after fetal allotransplantation. These findings demonstrate fetal resistance to GVHD following hematopoietic cell transplantation and elucidate Tregs as important contributors.

Regulatory T cells promote alloengraftment in a model of late-gestation in utero hematopoietic cell transplantation.

In utero hematopoietic cell transplantation (IUHCT) has the potential to cure congenital hematologic disorders including sickle cell disease. However, the window of opportunity for IUHCT closes with the acquisition of T-cell immunity, beginning at approximately 14 weeks gestation, posing significant technical challenges and excluding from treatment fetuses evaluated after the first trimester. Here we report that regulatory T cells can promote alloengraftment and preserve allograft tolerance after the acquisition of T-cell immunity in a mouse model of late-gestation IUHCT. We show that allografts enriched with regulatory T cells harvested from either IUHCT-tolerant or naive mice engraft at 20 days post coitum (DPC) with equal frequency to unenriched allografts transplanted at 14 DPC. Long-term, multilineage donor cell chimerism was achieved in the absence of graft-versus-host disease or mortality. Decreased alloreactivity among recipient T cells was observed consistent with donor-specific tolerance. These findings suggest that donor graft enrichment with regulatory T cells could be used to successfully perform IUHCT later in gestation.

Donor cell engineering with GSK3 inhibitor-loaded nanoparticles enhances engraftment after in utero transplantation.

Host cell competition is a major barrier to engraftment after in utero hematopoietic cell transplantation (IUHCT). Here we describe a cell-engineering strategy using glycogen synthase kinase-3 (GSK3) inhibitor-loaded nanoparticles conjugated to the surface of donor hematopoietic cells to enhance their proliferation kinetics and ability to compete against their fetal host equivalents. With this approach, we achieved remarkable levels of stable, long-term hematopoietic engraftment for up to 24 weeks post-IUHCT. We also show that the salutary effects of the nanoparticle-released GSK3 inhibitor are specific to donor progenitor/stem cells and achieved by a pseudoautocrine mechanism. These results establish that IUHCT of hematopoietic cells decorated with GSK3 inhibitor-loaded nanoparticles can produce therapeutic levels of long-term engraftment and could therefore allow single-step prenatal treatment of congenital hematological disorders.

Open Versus Laparoscopic Splenectomies in Children: A Comparative Study Performed at a Public Hospital in Brazil.

Introduction: In pediatric population, the two most common indications for splenectomy include traumatic rupture and hematological diseases such as hereditary spherocytosis, idiopathic thrombocytopenic purpura, sickle cell disease, and autoimmune hemolytic anemia. Traditionally, splenectomy has been an open procedure; however, since the first laparoscopic splenectomy was reported in 1991, the minimally invasive laparoscopic approach has become increasingly popular. In most public hospitals in Brazil, where vessel sealing devices are not available, most surgeons seem to prefer open splenectomy to guarantee intraoperative safety and improved outcomes. Objectives: To compare outcomes between open and laparoscopic splenectomy in children in a public hospital in Brazil. Materials and Methods: Retrospective study conducted between January 2010 and June 2018. Patients from 0 to 14 years old who underwent open or laparoscopic splenectomy at the University Hospital of Federal University of Paraná were included. Clinical, laboratory, imaging, and surgical data were collected. Results: For 8 years, 35 patients underwent splenectomy. Mean age was 4 years old and 54% were female. Of the 35 subjects, 69% had sickle cell anemia and 23% spherocytosis. The most common indication for surgery was a previous episode of splenic sequestration. The 13 laparoscopic surgeries were performed without harmonic scalpel or other vessel sealing devices. During the laparoscopic procedure, 2 patients experienced intraoperative complications: bleeding and prolonged surgical time due to technical problems with the equipment. Mean operative time was higher in laparoscopy group than in open group (186 minutes versus 66 minutes). Oral feeds began earlier on the laparoscopic group. Postoperatively, there were more complications on the open group, and no reoperations. There was only one fatality, likely secondary to fulminant sepsis, which occurred 34 days after the surgery in a patient who was undergoing prophylactic oral antibiotics therapy. Discussion: Performing laparoscopic splenectomy without harmonic scalpel or other vessel sealing devices is feasible, but it implicates in a significantly higher surgical time. Laparoscopic splenectomy had earlier oral feeds and fewer complications than open surgery.

In Utero Transplantation of Expanded Autologous Amniotic Fluid Stem Cells Results in Long-Term Hematopoietic Engraftment.

In utero transplantation (IUT) of hematopoietic stem cells (HSCs) has been proposed as a strategy for the prenatal treatment of congenital hematological diseases. However, levels of long-term hematopoietic engraftment achieved in experimental IUT to date are subtherapeutic, likely due to host fetal HSCs outcompeting their bone marrow (BM)-derived donor equivalents for space in the hematopoietic compartment. In the present study, we demonstrate that amniotic fluid stem cells (AFSCs; c-Kit+/Lin-) have hematopoietic characteristics and, thanks to their fetal origin, favorable proliferation kinetics in vitro and in vivo, which are maintained when the cells are expanded. IUT of autologous/congenic freshly isolated or cultured AFSCs resulted in stable multilineage hematopoietic engraftment, far higher to that achieved with BM-HSCs. Intravascular IUT of allogenic AFSCs was not successful as recently reported after intraperitoneal IUT. Herein, we demonstrated that this likely due to a failure of timely homing of donor cells to the host fetal thymus resulted in lack of tolerance induction and rejection. This study reveals that intravascular IUT leads to a remarkable hematopoietic engraftment of AFSCs in the setting of autologous/congenic IUT, and confirms the requirement for induction of central tolerance for allogenic IUT to be successful. Autologous, gene-engineered, and in vitro expanded AFSCs could be used as a stem cell/gene therapy platform for the in utero treatment of inherited disorders of hematopoiesis. Stem Cells 2019;37:1176-1188.