Bone Marrow-derived Hematopoietic Stem Cells Research Articles

Cross-talk between T Cells and Hematopoietic Stem Cells during Adoptive Cellular Therapy for Malignant Glioma.

Purpose: Adoptive T-cell immunotherapy (ACT) has emerged as a viable therapeutic for peripheral and central nervous system (CNS) tumors. In peripheral cancers, optimal efficacy of ACT is reliant on dendritic cells (DCs) in the tumor microenvironment. However, the CNS is largely devoid of resident migratory DCs to function as antigen-presenting cells during immunotherapy. Herein, we demonstrate that cellular interactions between adoptively transferred tumor-reactive T cells and bone marrow-derived hematopoietic stem and progenitor cells (HSPCs) lead to the generation of potent intratumoral DCs within the CNS compartment.Experimental Design: We evaluated HSPC differentiation during ACT in vivo in glioma-bearing hosts and HSPC proliferation and differentiation in vitro using a T-cell coculture system. We utilized FACS, ELISAs, and gene expression profiling to study the phenotype and function of HSPC-derived cells ex vivo and in vivo To demonstrate the impact of HSPC differentiation and function on antitumor efficacy, we performed survival experiments.Results: Transfer of HSPCs with concomitant ACT led to the production of activated CD86+CD11c+MHCII+ cells consistent with DC phenotype and function within the brain tumor microenvironment. These intratumoral DCs largely supplanted abundant host myeloid-derived suppressor cells. We determined that during ACT, HSPC-derived cells in gliomas rely on T-cell-released IFNγ to differentiate into DCs, activate T cells, and reject intracranial tumors.Conclusions: Our data support the use of HSPCs as a novel cellular therapy. Although DC vaccines induce robust immune responses in the periphery, our data demonstrate that HSPC transfer uniquely generates intratumoral DCs that potentiate T-cell responses and promote glioma rejection in situClin Cancer Res; 24(16); 3955-66. ©2018 AACR.

Direct comparison of the abilities of bone marrow mesenchymal versus hematopoietic stem cells to reverse hyperglycemia in diabetic NOD.SCID mice

ABSTRACTBoth bone marrow-derived hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC) improve glycemic control in diabetic mice, but their kinetics and associated changes in pancreatic morphology have not been directly compared. Our goal was to examine the time course of improvements in glucose tolerance and associated changes in β-cell mass and proliferation following transplantation of equivalent numbers of HSC or MSC from the same bone marrow into diabetic non-obese diabetic severe combined immune deficiency (NOD.SCID) mice. We used transgenic mice with a targeted expression of yellow fluorescent protein (YFP) driven by the Vav1 gene promoter to genetically tag HSC and progeny. HSC were separated from bone marrow by fluorescence-activated cell sorting and MSC following cell culture. Equivalent numbers of isolated HSC or MSC were transplanted directly into the pancreas of NOD.SCID mice previously made diabetic with streptozotocin. Glucose tolerance, serum insulin, β-cell mass and β-cell proliferation were examined up to 28 days following transplant. Transplantation with MSC improved glucose tolerance within 7 days and serum insulin levels increased, but with no increase in β-cell mass. Mice transplanted with HSC showed improved glucose tolerance only after 3 weeks associated with increased β-cell proliferation and mass. We conclude that single injections of either MSC or HSC transiently improved glycemic control in diabetic NOD.SCID mice, but with different time courses. However, only HSC infiltrated the islets and were associated with an expanded β-cell mass. This suggests that MSC and HSC have differing mechanisms of action.

Protocol for MicroRNA Transfer into Adult Bone Marrow-derived Hematopoietic Stem Cells to Enable Cell Engineering Combined with Magnetic Targeting.

While CD133+ hematopoietic stem cells (SCs) have been proven to provide high potential in the field of regenerative medicine, their low retention rates after injection into injured tissues as well as the observed massive cell death rates lead to very restricted therapeutic effects. To overcome these limitations, we sought to establish a non-viral based protocol for suitable cell engineering prior to their administration. The modification of human CD133+ expressing SCs using microRNA (miR) loaded magnetic polyplexes was addressed with respect to uptake efficiency and safety as well as the targeting potential of the cells. Relying on our protocol, we can achieve high miR uptake rates of 80-90% while the CD133+ stem cell properties remain unaffected. Moreover, these modified cells offer the option of magnetic targeting. We describe here a safe and highly efficient procedure for the modification of CD133+ SCs. We expect this approach to provide a standard technology for optimization of therapeutic stem cell effects and for monitoring of the administered cell product via magnetic resonance imaging (MRI).

Protocol for MicroRNA Transfer into Adult Bone Marrow-derived Hematopoietic Stem Cells to Enable Cell Engineering Combined with Magnetic Targeting

Protocol for MicroRNA Transfer into Adult Bone Marrow-derived Hematopoietic Stem Cells to Enable Cell Engineering Combined with Magnetic Targeting

Evaluating role of bone marrow-derived stem cells in dry age-related macular degeneration using multifocal electroretinogram and fundus autofluorescence imaging.

To evaluate the role of bone marrow-derived stem cells in the treatment of advanced dry age-related macular degeneration (AMD) using multifocal electroretinogram (mf-ERG) and fundus autofluorescence imaging. Thirty patients (60 eyes) with bilateral central geographic atrophy (GA) were recruited. Worse eye of each patient received autologous bone marrow-derived hematopoietic stem cells (BM-HSCs) (group 1) and the fellow eye with better visual acuity served as control (group 2). The effect of stem cell therapy was determined in terms of visual acuity, amplitude and implicit time in mf-ERG and size of GA on fundus autofluorescence imaging. These tests were performed at presentation and first, third and sixth month follow up. Adverse events (if any) were also monitored. At 6mo follow-up there was no statistically significant improvement in median logMAR best corrected visual acuity (BCVA) in either group. Mf-ERG revealed significant improvement in amplitude and implicit time in the intervention group. A significant decrease was also noted in greatest linear dimension (GLD) of GA in the eyes receiving stem cells [6.78±2.60 mm at baseline to 6.56±2.59 mm at 6mo (P=0.021)]. However, no such improvement was noted in the control group. Electrophysiological and anatomical improvement in the intervention group sheds light on the therapeutic role of BM-HSCs. Further studies are required to determine the stage of disease at which the maximal benefit can be achieved and to standardize the dose and frequency of stem cell injection.

Bone Marrow Adipose Tissue Deficiency Increases Disuse-Induced Bone Loss in Male Mice

Bone marrow adipose tissue (MAT) is negatively associated with bone mass. Since osteoblasts and adipocytes are derived from the same precursor cells, adipocyte differentiation may occur at the expense of osteoblast differentiation. We used MAT-deficient KitW/W−v (MAT-) mice to determine if absence of MAT reduced bone loss in hindlimb-unloaded (HU) mice. Male MAT- and wild-type (WT) mice were randomly assigned to a baseline, control or HU group (n = 10 mice/group) within each genotype and HU groups unloaded for 2 weeks. Femurs were evaluated using micro-computed tomography, histomorphometry and targeted gene profiling. MAT- mice had a greater reduction in bone volume fraction after HU than did WT mice. HU MAT- mice had elevated cancellous bone formation and resorption compared to other treatment groups as well as a unique profile of differentially expressed genes. Adoptive transfer of WT bone marrow-derived hematopoietic stem cells reconstituted c-kit but not MAT in KitW/W−v mice. The MAT- WT → KitW/W−v mice lost cancellous bone following 2 weeks of HU. In summary, results from this study suggest that MAT deficiency was not protective, and was associated with exaggerated disuse-induced cancellous bone loss.

Nicaraven, a Potential Radioprotective Agent, has Very Limited Effects on the Survival of Cancer Cells and the Growth of Established Tumors

Radiotherapy is one of the major treatment modalities for the management of various cancers, however, it is limited by the severe side effects and complications experienced by some patients. Nicaraven, a chemically synthesized hydroxyl radical-specific scavenger, has been shown to protect normal tissues from radiation-induced injury. We investigated the role of nicaraven in cancer cells and tumor growth. While nicaraven did not significantly change the colony-forming abilities and DNA damage levels in several cancer cell lines after irradiation, it significantly protected mouse bone marrow-derived hematopoietic stem cells from radiation injury. In established mouse tumor models in which radiation exposure significantly inhibited the growth of tumors, nicaraven did not significantly mitigate the radiation-induced inhibition of tumor growth. The results of this study showed that while nicaraven attenuated the toxicity of radiotherapy in hematopoietic stem cells, it had very limited effects on the survival o...

Nicaraven, a Potential Radioprotective Agent, has Very Limited Effects on the Survival of Cancer Cells and the Growth of Established Tumors.

Radiotherapy is one of the major treatment modalities for the management of various cancers, however, it is limited by the severe side effects and complications experienced by some patients. Nicaraven, a chemically synthesized hydroxyl radical-specific scavenger, has been shown to protect normal tissues from radiation-induced injury. We investigated the role of nicaraven in cancer cells and tumor growth. While nicaraven did not significantly change the colony-forming abilities and DNA damage levels in several cancer cell lines after irradiation, it significantly protected mouse bone marrow-derived hematopoietic stem cells from radiation injury. In established mouse tumor models in which radiation exposure significantly inhibited the growth of tumors, nicaraven did not significantly mitigate the radiation-induced inhibition of tumor growth. The results of this study showed that while nicaraven attenuated the toxicity of radiotherapy in hematopoietic stem cells, it had very limited effects on the survival of cancer cells and tumor growth. Nicaraven may be an ideal drug for mitigating the side effects of radiotherapy in patients with cancer.

VLA-4 Affinity Assay for Murine Bone Marrow-derived Hematopoietic Stem Cells.

Hematopoietic stem cells (HSCs) are defined by their functional ability to self-renew and to differentiate into all blood cell lineages. The majority of HSC reside in specific anatomical locations in the bone marrow (BM) microenvironment, in a quiescent non motile mode. Adhesion interactions between HSCs and their supporting BM microenvironment cells are critical for maintaining stem cell quiescence and protection from DNA damaging agents to prevent hematology failure and death. Multiple signaling proteins play a role in controlling retention and migration of bone marrow HSCs. Adhesion molecules are involved in both processes regulating hematopoiesis and stem- and progenitor-cell BM retention, migration and development. The mechanisms underlying the movement of stem cells from and to the marrow have not been completely elucidated and are still an object of intense study. One important aspect is the modification of expression and affinity of adhesion molecules by stem and progenitor cells which are required both for stem cell retention, migration and development. Adhesion is regulated by expression of the adhesion molecules, their affinity and avidity. Affinity regulation is related to the molecular binding recognition and bond strength. Here, we describe the in vitro FACS assay used in our research to explore the expression, affinity and function of the integrin α4β1 (also termed VLA-4) for murine bone marrow retained EPCR+ long term repopulation HSC (LT-HSC) (Gur- Cohen et al., 2015 ).

Orientation-specific RAG activity in chromosomal loop domains contributes to Tcrd V(D)J recombination during T cell development.

T cell antigen receptor δ (Tcrd) variable region exons are assembled by RAG-initiated V(D)J recombination events in developing γδ thymocytes. Here, we use linear amplification-mediated high-throughput genome-wide translocation sequencing (LAM-HTGTS) to map hundreds of thousands of RAG-initiated Tcrd D segment (Trdd1 and Trdd2) rearrangements in CD4(-)CD8(-) double-negative thymocyte progenitors differentiated in vitro from bone marrow-derived hematopoietic stem cells. We find that Trdd2 joins directly to Trdv, Trdd1, and Trdj segments, whereas Trdd1 joining is ordered with joining to Trdd2, a prerequisite for further rearrangement. We also find frequent, previously unappreciated, Trdd1 and Trdd2 rearrangements that inactivate Tcrd, including sequential rearrangements from V(D)J recombination signal sequence fusions. Moreover, we find dozens of RAG off-target sequences that are generated via RAG tracking both upstream and downstream from the Trdd2 recombination center across the Tcrd loop domain that is bounded by the upstream INT1-2 and downstream TEA elements. Disruption of the upstream INT1-2 boundary of this loop domain allows spreading of RAG on- and off-target activity to the proximal Trdv domain and, correspondingly, shifts the Tcrd V(D)J recombination landscape by leading to predominant V(D)J joining to a proximal Trdv3 pseudogene that lies just upstream of the normal boundary.

ShRNA-Induced Gene Knockdown In Vivo to Investigate Neutrophil Function.

To silence genes in neutrophils efficiently, we exploited the RNA interference and developed an shRNA-based gene knockdown technique. This method involves transfection of mouse bone marrow-derived hematopoietic stem cells with retroviral vector carrying shRNA directed at a specific gene. Transfected stem cells are then transplanted into irradiated wild-type mice. After engraftment of stem cells, the transplanted mice have two sets of circulating neutrophils. One set has a gene of interest knocked down while the other set has full complement of expressed genes. This efficient technique provides a unique way to directly compare the response of neutrophils with a knocked-down gene to that of neutrophils with the full complement of expressed genes in the same environment.

Co-infusion of insulin-secreting adipose tissue-derived mesenchymal stem cells and hematopoietic stem cells: novel approach to management of type 1 diabetes mellitus

Stem cell therapy (SCT) has promising results in regeneration of injured tissues/cells as well as correcting immune dysregulation. We present our experience of co-infusion of human adipose tissue-derived insulin-secreting mesenchymal stem cells (IS-AD-MSC) along with bone marrow-derived hematopoietic stem cells (BM-HSC) in type 1 diabetes mellitus (T1DM). This was an institutional review board-approved prospective non-randomized open-labeled clinical trial after informed consent of 20 patients (15 males and 5 females) with T1DM for SCT, with mean disease duration of 9 ± 5.51 years. Their mean age and weight were 19.95 ± 8.35 years and 49.9 ± 14 kg, respectively. Our study includes T1DM with positive for glutamic acid decarboxylase (GAD) antibody and history of diabetic ketoacidosis (DKA). Generated IS-AD-MSC and BM-HSC were infused via femoral catheterization under local anesthesia into portal + thymic circulation and subcutaneous tissue with conditioning of injection rabbit anti-thymocyte globulin and Bortezomib. Patients were monitored for blood sugar, serum C-peptide, GAD antibodies, and glycosylated hemoglobin (Hb1Ac) at three monthly intervals post-therapy. Mean SC quantum infused 99.45 ± 22.5 mL, with mean 2.38 ± 0.78 × 104 ISC/μL, mean CD34+ 0.57 %, and mean CD45-/90+ and CD45-/73+ were 47.22 and 24.66 %, respectively. Generated ISCs expressed transcription factors ISL-1, PAX-6, and IPF-1. Variable and sustained improvement in mean FBS, PPBS, HbA1c, and serum C-peptide was noted over a mean follow-up of 43.94 ± 19.8 months with mean reduction of GAD antibody from 525.15 to 120.15 IU/mL. Mean insulin requirement decreased from 60.89 to 39.76 IU/day. There was absence of DKA after SCT. No untoward effect/morbidity/mortality was recorded from SCT. Co-infusion of IS-AD-MSC with BM-HSC offers a safe and viable therapy for T1DM.

Lineage-related and particle size-dependent cytotoxicity of chitosan nanoparticles on mouse bone marrow-derived hematopoietic stem and progenitor cells

Chitosan nanoparticles (CSNPs) have potential applications in stem cell research. In this study, ex vivo cytotoxicity of CSNPs on mouse bone marrow-derived (MBMCs) hematopoietic stem and progenitor cells (HSPCs) was determined. MBMCs were exposed to CSNPs of different particle sizes at various concentrations for up to 72 h. Cytotoxicity effect of CSNPs on MBMCs was determined using MTT, Live/Dead Viability/Cytotoxicity assays and flow cytometry analysis of surface antigens on HSCs (Sca-1+), myeloid-committed progenitors (CD11b+, Gr-1+), and lymphoid-committed progenitors (CD45+, CD3e+). At 24 h incubation, MBMCs' viability was not affected by CSNPs. At 48 and 72 h, significant reduction was detected at higher CSNPs concentrations. Small CSNPs (200 nm) significantly reduced MBMCs' viability while medium-sized particle (∼400 nm) selectively promoted MBMCs growth. Surface antigen assessment demonstrated lineage-dependent effect. Significant decrease in Sca-1+ cells percentage was observed for medium-sized particle at the lowest CSNPs concentration. Meanwhile, reduction of CD11b+ and Gr-1+ cells percentage was detected at high and intermediate concentrations of medium-sized and large CSNPs. Percentage of CD45+ and CD3e+ cells along with ROS levels were not significantly affected by CSNPs. In conclusion, medium-sized and large CSNPs were relatively non-toxic at lower concentrations. However, further investigations are necessary for therapeutic applications.

Immunological Basis for Rapid Progression of Diabetes in Older NOD Mouse Recipients Post BM-HSC Transplantation.

Type I diabetes (T1D), mediated by autoreactive T cell destruction of insulin-producing islet beta cells, has been treated with bone marrow-derived hematopoietic stem cell (BM-HSC) transplantation. Older non-obese diabetic (NOD) mice recipients (3m, at disease-onset stage) receiving syngeneic BM-HSC progressed more rapidly to end-stage diabetes post-transplantation than younger recipients (4-6w, at disease-initiation stage). FACS analyses showed a higher percentage and absolute number of regulatory T cells (Treg) and lower proportion of proliferating T conventional cells (Tcon) in pancreatic lymph nodes from the resistant mice among the younger recipients compared to the rapid progressors among the older recipients. Treg distribution in spleen, mesenteric lymph nodes (MLN), blood and thymus between the two groups was similar. However, the percentage of thymic Tcon and the proliferation of Tcon in MLN and blood were lower in the young resistants. These results suggest recipient age and associated disease stage as a variable to consider in BM-HSC transplantation for treating T1D.

Insulin-secreting adipose-derived mesenchymal stromal cells with bone marrow–derived hematopoietic stem cells from autologous and allogenic sources for type 1 diabetes mellitus

Background aimsStem cell therapy (SCT) is now the up-coming therapeutic modality for treatment of type 1 diabetes mellitus (T1DM). MethodsOur study was a prospective, open-labeled, two-armed trial for 10 T1DM patients in each arm of allogenic and autologous adipose–derived insulin-secreting mesenchymal stromal cells (IS-AD-MSC)+bone marrow–derived hematopoietic stem cell (BM-HSC) infusion. Group 1 received autologous SCT: nine male patients and one female patient; mean age, 20.2 years, disease duration 8.1 years; group 2 received allogenic SCT: six male patients and four female patients, mean age, 19.7 years and disease duration, 7.9 years. Glycosylated hemoglobin (HbA1c) was 10.99%; serum (S.) C-peptide, 0.22 ng/mL and insulin requirement, 63.9 IU/day in group 1; HbA1c was 11.93%, S.C-peptide, 0.028 ng/mL and insulin requirement, 57.55 IU/day in group 2. SCs were infused into the portal+thymic circulation and subcutaneous tissue under non-myelo-ablative conditioning. Patients were monitored for blood sugar, S.C-peptide, glutamic acid decarboxylase antibodies and HbA1c at 3-month intervals. ResultsGroup 1 received mean SCs 103.14 mL with 2.65 ± 0.8 × 104 ISCs/kg body wt, CD34+ 0.81% and CD45−/90+/73+, 81.55%. Group 2 received mean SCs 95.33 mL with 2.07 ± 0.67 × 104 ISCs/kg body wt, CD34+ 0.32% and CD45−/90+/73+ 54.04%. No untoward effect was observed with sustained improvement in HbA1c and S.C-peptide in both groups with a decrease in glutamic acid decarboxylase antibodies and reduction in mean insulin requirement. ConclusionsSCT is a safe and viable treatment option for T1DM. Autologous IS-AD-MSC+ BM-HSC co-infusion offers better long-term control of hyperglycemia as compared with allogenic SCT.

Human adipose-derived stem cells ameliorate cigarette smoke-induced murine myelosuppression via secretion of TSG-6.

Bone marrow-derived hematopoietic stem and progenitor cells (HSC/HPC) are critical to homeostasis and tissue repair. The aims of this study were to delineate the myelotoxicity of cigarette smoking (CS) in a murine model, to explore human adipose-derived stem cells (hASC) as a novel approach to mitigate this toxicity, and to identify key mediating factors for ASC activities. C57BL/6 mice were exposed to CS with or without i.v. injection of regular or siRNA-transfected hASC. For in vitro experiments, cigarette smoke extract was used to mimic the toxicity of CS exposure. Analysis of bone marrow HPC was performed both by flow cytometry and colony-forming unit assays. In this study, we demonstrate that as few as 3 days of CS exposure results in marked cycling arrest and diminished clonogenic capacity of HPC, followed by depletion of phenotypically defined HSC/HPC. Intravenous injection of hASC substantially ameliorated both acute and chronic CS-induced myelosuppression. This effect was specifically dependent on the anti-inflammatory factor TSG-6, which is induced from xenografted hASC, primarily located in the lung and capable of responding to host inflammatory signals. Gene expression analysis within bone marrow HSC/HPC revealed several specific signaling molecules altered by CS and normalized by hASC. Our results suggest that systemic administration of hASC or TSG-6 may be novel approaches to reverse CS-induced myelosuppression.

Stem cell-based regenerative opportunities for the liver: State of the art and beyond

The existing mismatch between the great demand for liver transplants and the number of available donor organs highlights the urgent need for alternative therapeutic strategies in patients with acute or chronic liver failure. The rapidly growing knowledge on stem cell biology and the intrinsic repair processes of the liver has opened new avenues for using stem cells as a cell therapy platform in regenerative medicine for hepatic diseases. An impressive number of cell types have been investigated as sources of liver regeneration: adult and fetal liver hepatocytes, intrahepatic stem cell populations, annex stem cells, adult bone marrow-derived hematopoietic stem cells, endothelial progenitor cells, mesenchymal stromal cells, embryonic stem cells, and induced pluripotent stem cells. All these highly different cell types, used either as cell suspensions or, in combination with biomaterials as implantable liver tissue constructs, have generated great promise for liver regeneration. However, fundamental questions still need to be addressed and critical hurdles to be overcome before liver cell therapy emerges. In this review, we summarize the state-of-the-art in the field of stem cell-based therapies for the liver along with existing challenges and future perspectives towards a successful liver cell therapy that will ultimately deliver its demanding goals.

Cell-Cell Communication Networks Propose a Modulation of the Hematopoietic Stem Cell Niche by Invading Breast Carcinoma Cells

Background: The human bone marrow can become a target of disseminated tumor cells in a relevant proportion of breast cancer patients. However, the underlying pathophysiology is incompletely understood. This study aims to identify and characterize potential mechanisms modulating the bone marrow hematopoietic microenvironment by invading breast cancer cells (BCC) as a basis for experimental evaluation. Methods: Static cell-cell communication networks, representing the integrated signaling among breast carcinoma cell lines (MCF-7 or MDA-MB-231), bone marrow-derived mesenchymal stromal cells (MSC) and hematopoietic stem and progenitor cells (HSPC), were constructed in-silico by combining differentially overexpressed genes of the involved cell populations with known ligand-receptor interactions. Using the networks as guidance, pathophysiological relevance of the analyzed populations to breast cancer-initiated hematologic abnormalities was appraised by systematic literature mining. In-vitro co-culture modeling was performed to evaluate the paracrine effects of BCC on MSC-HSPC signaling and to validate main implications of the exposed signaling network. Results: Breast cancer cells exhibited intensive bidirectional intercellular signaling with MSC and to a lesser extent with HSPC. BCC-derived signals were reported to recruit MSC to sites of breast cancer, activate tumor associated fibroblasts (TAF) and modify MSC differentiation. Hematopoietic microenvironment-derived signals were predominantly associated with BCC attraction and metastatic progression. Potential ligands that protect from metastases were exclusively HSPCderived. In-vitro co-culture modeling revealed that BCC mediated loss of the niche-derived hematopoiesis-supporting factor SDF-1 and the emergence of FGF-2 in the MSC-HSPC interaction. Conclusion: We propose a modulation of MSC by BCC, inter alia via the FGF-2/FGFR1 pathway, resulting in activation of TAF, generation of a vascularized tumor stroma, breast cancer progression and consequential impairment of hematopoiesis by reduction of SDF-1 levels. Those indirect changes in the HSC niche upon BCC invasion might increase the vulnerability for bone metastasis in breast cancer patients.

Hematopoietic Engraftment of Amniotic Fluid Stem Cells Following in Utero Transplantation

IntroductionAmniotic fluid stem cells (AFSC) are an appealing cell source for prenatal treatment of congenital blood disorders. They can be obtained safely during amniocentesis, are autologous to the fetus, and have shown hematopoietic potential when transplanted postnatally. Ex-vivo expansion to obtain adequate cell numbers is required for the clinical use of AFSC for in utero transplantation (IUT). The aim of this study was to assess long-term hematopoietic engraftment of freshly-isolated and cultured AFSC post IUT in mice, and compare it to that achieved following IUT of adult, bone marrow-derived hematopoietic stem cells (BM-HSC).MethodsLineage-depleted/c-Kit+ AFSC were isolated at embryonic day 13 (E13) from C57BL/6TgN(act-EGFP)OsbY01 (GFP) dams. AFSC were cultured for 7 days on mitotically-inactivated mouse embryonic fibroblasts with mouse embryonic stem cell media, and were sorted by flow cytometry (GFP+/c-Kit+) prior to IUT. BM-HSC (lineage-depleted/c-Kit+/Sca-1+) were isolated from 6-week old GFP mice. 104 AFSC (fresh or cultured) or BM-HSC (fresh) were injected intravenously into E14 C57BL/6J fetuses representing a congenic (autologous-like) IUT. Donor cell engraftment was assessed in the peripheral blood (PB) at 4 and 12 weeks of age by flow cytometry (% GFP+ cells within CD45+ population). Lineage characterization of engrafted cells was performed at both time points using antibodies against lymphoid (CD3, B220), and myeloid (CD11b, Gr-1) cell surface markers. Results are expressed as mean±SEM, and statistical analysis was performed using 1- or 2-way ANOVA with Bonferroni post-hoc tests. Experimental protocols were approved by the Institutional Animal Care and Use Committee at The Children’s Hospital of Philadelphia.ResultsFreshly-isolated AFSC expressed pluripotency (Oct-4, c-Myc, Klf-4) and hematopoietic markers (Sca-1+: 34.1±8.3%, CD34+: 10.6±3.1%, CD45+: 97.9±2.7%). Cultured AFSC had a doubling time of 3.2±0.2 days, and 80.7±1.6% of cells maintained c-Kit expression after 7 days of culture. c-Kit+ cultured AFSC expressed pluripotency and hematopoietic markers at similar levels as fresh AFSC. Array analysis of hematopoietic genes demonstrated significant under-expression of hematopoiesis-related transcription factors and regulators (including Gata1, Gata2, and Lmo2) in fresh and cultured AFSC compared to BM-HSC. Fetal survival rate was comparable following IUT with fresh AFSC (14/23; 60.9%), cultured AFSC (13/21; 61.9%) and BM-HSC (16/26; 61.5%) (p=0.9). Successful hematopoietic engraftment was seen at 4 weeks of age in pups that underwent fresh and cultured AFSC IUT, with comparable PB levels between groups (fresh AFSC: 21.9±1.0% vs. cultured AFSC: 20.4±1.4%; p=0.9). In contrast, IUT of BM-HSC resulted in hematopoietic micro-chimerism (engraftment: 0.04±0.02%; p<0.0001 vs. fresh and cultured AFSC). Hematopoietic engraftment was maintained in fresh and cultured AFSC groups at 12 weeks of age (fresh AFSC: 21.6±1.1% vs. cultured AFSC: 19.4±2.4%; p=0.9), and donor cell characterization demonstrated multi-lineage hematopoietic differentiation, with distribution similar to that of host cells (p=0.8).ConclusionsCongenic (autologous-like) IUT of AFSC results in successful multi-lineage hematopoietic engraftment in immune-competent mice, which is superior to that achieved with BM-HSC. AFSC can be expanded in vitro without differentiation, and the hematopoietic potential of cultured cells post IUT is similar to that achieved with freshly-isolated AFSC. Combined with gene therapy, IUT of autologous AFSC could be a promising approach for prenatal treatment of congenital blood disorders. DisclosuresNo relevant conflicts of interest to declare.

Cell Engineering with Glycogen Synthase Kinase-3 Beta Inhibitor-Loaded Synthetic Nanoparticles Enhances Hematopoietic Engraftment of Bone Marrow Mononuclear Cells Following in Utero Transplantation

IntroductionIn utero hematopoietic cell transplantation (IUHCT) has tremendous potential for prenatal treatment of congenital hematological disorders, but clinical application has been limited by low engraftment levels. Host cell competition is one of the most formidable barriers to successful engraftment post IUHCT, as fetal stem cells have a proliferative advantage over their postnatal equivalents. Glycogen synthase kinase-3 beta (GSK3β) inhibition has been shown to augment expansion kinetics of bone marrow-derived hematopoietic stem cells (HSC), resulting in enhanced repopulating capacity in vivo. We have developed a strategy that allows targeted, sustained delivery of a GSK3β inhibitor to donor cells by conjugating biodegradable nanocarriers to the cell surface. The aim of the present study was to determine whether donor cell engineering with GSK3β inhibitor-loaded nanoparticles enhances hematopoietic engraftment following IUHCT.MethodsBone marrow mononuclear cells (MNC) were isolated from 6-week old C57BL/6TgN(act-EGFP)OsbY01 mice. GSK3β inhibitor (CHIR99021) loaded multilamelar lipid vehicles (MLV) were synthesized from simple liposomes with the addition of divalent cations to induce liposome fusion. The presence of thiol-reactive maleimide groups in MLV lipid bilayers allowed stable conjugation to the cell membrane of donor MNC. IUHCT was performed in Balb/c mice at E14 and 107 MNC were injected intravenously into each fetus. Donor cell engraftment was assessed in peripheral blood at 4 and 12 weeks of age by flow cytometry (% GFP+ cells within CD45+ population). Comparisons were made between animals that received untreated MNC (control), MNC conjugated with inhibitor-loaded MLV (CHIR99021-MLV), and MNC co-injected with a bolus dose of the inhibitor equivalent to that loaded in MLV (CHIR99021-bolus). Lineage characterization of donor cells was performed using antibodies against lymphoid (CD3, B220), and myeloid (CD11b, Gr-1) cell surface markers. Results are expressed as mean±SEM, and statistical analysis was performed using 1- or 2-way ANOVA with Bonferroni post-hoc tests. Experimental protocols were approved by the Institutional Animal Care and Use Committee at The Children’s Hospital of Philadelphia.ResultsMLV had a diameter of 489±8nm, and contained 21.7±2.1μg CHIR99021 per 1010 nanoparticles. Inhibitor release was gradual, with 92.7±0.2% of the encapsulated mass released within 7 days. 64±9 nanoparticles were conjugated on each donor cell, resulting in inhibitor dose of 1.3*10-7μg per cell (1.3μg or 4mg/kg per fetus). MLV conjugation did not affect the ability of MNC to migrate to fetal hematopoietic organs post IUHCT. Fetal survival was comparable in control (20/27; 74.1%) and CHIR99021-MLV (10/12; 83.3%) groups, but was reduced in the CHIR99021-bolus group (7/15; 46.7%; p<0.05). Sustained in vivo release of the inhibitor in CHIR99021-MLV animals resulted in increased donor cell engraftment at 4 weeks of age (52.9±2.8%) that was 3 times greater to that observed in control animals (15.4±1.4%; p<0.0001). Bolus CHIR99021 administration had no effect on engraftment (10.5±2.0%; p<0.0001 vs. CHIR99021-MLV, p=0.6 vs. control). Engraftment levels were lower at 12 weeks in control and bolus-CHIR99021 groups (control: 5.9±0.8%, bolus-CHIR99021: 4.5±1.7%; p<0.05 vs. 4 weeks), but were maintained in CHIR99021-MLV offspring (48.3±2.2%; p<0.0001 vs. control and bolus-CHIR99021). Donor cell characterization showed multi-lineage hematopoietic differentiation, with distribution similar to that of host cells and no difference between experimental groups (p=0.6). In vitro pre-treatment for 7 days with the same amount of CHIR99021 per cell resulted in enhanced HSC (lineage-/c-Kit+/Sca-1+) proliferation (p<0.01 vs. control) and augmented their ability to generate hematopoietic progenitors (p<0.05 vs. control), by modulating the Wnt, Notch and Hedgehog pathways.ConclusionCell engineering with GSK3β inhibitor-loaded synthetic nanoparticles enhances hematopoietic engraftment of BM-MNC following IUHCT. Prolonged retention of the biodegradable nanocarriers on donor cell surfaces enables sustained CHIR99021 release, and allows pseudo-autocrine bioactivity. Conjugation of drug-loaded particles directly to donor cells allows targeted augmentation of HSC function, and could markedly increase the therapeutic potential of IUHCT. DisclosuresNo relevant conflicts of interest to declare.