Kinetics of cytokine receptor internalization under steady-state conditions affects growth of neighboring blood cells

Modular Layer-by-Layer Nanoparticle Platform for Hematopoietic Progenitor and Stem Cell Targeting

Effective delivery of drug and gene cargos to hematopoietic stem and progenitor cells (HSPCs) is a major challenge. Current therapeutic strategies in genetic disorders or hematological malignancies are hindered by high costs, low accessibility, and high off-target toxicities. Layer-by-layer nanoparticles (LbL NPs) are modular systems with tunable surface properties to enable highly specific targeting. In this work, we developed LbL NPs that target HSPCs via antibody functionalization with reduced off-target uptake by circulating myeloid cells. NPs layered with poly(acrylic acid), a bioinert polymer, provided more stealth properties in vivo than other tested bioactive polyanions. The additional conjugation of anti-cKit and anti-CD90 antibodies improved NP uptake by 2- to 3-fold in nondifferentiated bone marrow cells in vitro. By contrast, anti-CD105 functionalized NPs showed the highest association to HSPCs in vivo, ranging from 3.0 to 8.5% in progenitor subpopulations. This LbL NP platform was then adapted to target human HSPC receptors, with similar targeting trends in healthy CD34+ human cells. By contrast, anti-CXCR4 functionalization demonstrated the greatest targeting to human B-cell lymphoma and leukemia cells. Taken together, these results underscore the therapeutic potential of this modular LbL NP platform with the capacity to target HSPCs in a disease-dependent context.

Oral Immunisation With Non-GMO Surface Displayed SARS-CoV-2 Spike Epitopes on Bacteria-Like Particles Provokes Robust Humoral and Cellular Immune Responses, and Modulated the Gut Microbiome in Mice

The coronavirus disease 2019 (COVID-19) is a fatal disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). To date, several vaccines have been developed to combat the spread of this virus. Mucosal vaccines using food-grade bacteria, such as Lactobacillus spp., are promising strategies for developing safe and effective vaccines against SARS-CoV-2. In this study, we designed a non-GMO surface-displayed SARS-CoV-2 spike S1 epitope on Limosilactobacillus fermentum-derived bacteria-like particles (BLPs). After that, we evaluated its efficacy to induce immune responses in immunocompetent mice. Moreover, we examined the influence of oral immunisation on the gut microbiome and microbiota metabolites. Twenty-eight 6-week-old male C57BL/6 mice were orally immunised with the following: PBS (control), Lm. fermentum-derived BLPs only, BLPs displaying SARS-CoV-2 spike S1-2, or BLPs displaying SARS-CoV-2 spike S1-3 epitopes. Our results showed that mucosal immunisation of mice with surface-displayed SARS-CoV-2 spike epitopes provoked high-level secretory IgA and systemic IgG production. Moreover, the immunisation exhibited a Th1-like immune response, characterised by an elevated IgG2a-to-IgG1 ratio and high antiviral IFN-γ production. In addition, we observed gut microbiome modulation and increased butyrate production in immunised mice. Overall, the use of Lm. fermentum-derived BLPs and the anchor CshA to display SARS-CoV-2 spike S1epitopes is a promising novel strategy in developing a cost-effective, non-GMO mucosal vaccine alternative against SARS-CoV-2.

Cell Adhesion and Local Cytokine Control on Protein-Functionalized PNIPAM-co-AAc Hydrogel Microcarriers

Achieving adequate cell densities remains a major challenge in establishing economic biotechnological and biomedical processes. A possible remedy is microcarrier-based cultivation in stirred-tank bioreactors (STBR), which offers a high surface-to-volume ratio, appropriate process control, and scalability. However, despite their potential, commercial microcarriers are currently limited to material systems featuring unnatural mechanical properties and low adaptability. Because matrix stiffness and ligand presentation impact phenotypical attributes, differentiation potential, and genetic stability, biotechnological processes can significantly benefit from microcarrier systems tailorable toward cell-type specific requirements. This study introduces hydrogel particles co-polymerized from poly(N-isopropylacrylamide) (PNIPAM) and acrylic acid (AAc) as a platform technology for cell expansion. The resulting microcarriers exhibit an adjustable extracellular matrix-like softness, an adaptable gel charge, and functional carboxyl groups, allowing electrostatic and covalent coupling of cell adhesive and cell fate-modulating proteins. These features enable the attachment and growth of L929 mouse fibroblast cells in static microtiter plates and dynamic STBR cultivations while also providing vital growth factors, such as interleukin-3, to myeloblast-like 32D cells over 20 days of cultivation. The study explores the effects of different educt compositions on cell-particle interactions and reveals that PNIPAM-co-AAc microcarriers can provide both covalently coupled and diffusively released cytokine to adjacent cells.

Multiorgan failure with abnormal receptor metabolism in mice mimicking Samd9/9L syndromes

Autosomal dominant sterile α motif domain containing 9 (Samd9) and Samd9L (Samd9/9L) syndromes are a large subgroup of currently established inherited bone marrow failure syndromes that includes myelodysplasia, infection, growth restriction, adrenal hypoplasia, genital phenotypes, and enteropathy (MIRAGE), ataxia pancytopenia, and familial monosomy 7 syndromes. Samd9/9L genes are located in tandem on chromosome 7 and have been known to be the genes responsible for myeloid malignancies associated with monosomy 7. Additionally, as IFN-inducible genes, Samd9/9L are crucial for protection against viruses. Samd9/9L syndromes are caused by gain-of-function mutations and develop into infantile myelodysplastic syndromes associated with monosomy 7 (MDS/-7) at extraordinarily high frequencies. We generated mice expressing Samd9LD764N, which mimic MIRAGE syndrome, presenting with growth retardation, a short life, bone marrow failure, and multiorgan degeneration. In hematopoietic cells, Samd9LD764N downregulates the endocytosis of transferrin and c-Kit, resulting in a rare cause of anemia and a low bone marrow reconstitutive potential that ultimately causes MDS/-7. In contrast, in nonhematopoietic cells we tested, Samd9LD764N upregulated the endocytosis of EGFR by Ship2 phosphatase translocation to the cytomembrane and activated lysosomes, resulting in the reduced expression of surface receptors and signaling. Thus, Samd9/9L is a downstream regulator of IFN that controls receptor metabolism, with constitutive activation leading to multiorgan dysfunction.