Nanocell COVID-19 vaccine triggers a novel immune response pathway producing high-affinity antibodies which neutralize all variants of concern.

Most current anti-viral vaccines elicit a humoral and cellular immune response via the pathway of phagocytic cell mediated viral antigen presentation to B and T cell surface receptors. However, this pathway results in reduced ability to neutralize S-protein Receptor Binding Domains (RBDs) from several Variants of Concern (VOC) and the rapid waning of memory B cell response requiring vaccine reformulation to cover dominant VOC S-proteins and multiple boosters. Here we show for the first time in mice and humans, that a bacterially derived, non-living, nanocell (EDV; EnGeneIC Dream Vector) packaged with plasmid expressed SARS-CoV-2 S-protein and α-galactosyl ceramide adjuvant (EDV-COVID-αGC), stimulates an alternate pathway due to dendritic cells (DC) displaying both S-polypeptides and αGC thereby recruiting and activating iNKT cells with release of IFNγ. This triggers DC activation/maturation, activation of follicular helper T cells (TFH), cognate help to B cells with secretion of a cytokine milieu promoting B cell maturation, somatic hypermutation in germinal centers to result in high affinity antibodies. Surrogate virus neutralization tests show 90-100% neutralization of ancestral and early VOC in mice and human trial volunteers. EDV-COVID-αGC as a third dose booster neutralized Omicron BA. 4/5. Serum and PBMC analyses reveal long lasting S-specific memory B and T cells. In contrast, control EDVs lacking αGC, did not engage the iNKT/DC pathway resulting in antibody responses unable to neutralize all VOCs and had a reduced B cell memory. The vaccine is lyophilized, stored and transported at room temperature with a shelf-life of over a year.

Scaffolds for islets and stem cells differentiated into insulin-secreting cells.

Embryonic/pluripotent stem cells offer the possibility of an unlimited source of cells to be differentiated into beta cells. This requires differentiating the stem cells into pancreatic progenitors by tissue culture, and then transplanting into recipients for the final stages of development into mature beta-cells. Exposing embryonic stem cells seeded onto laminin coated PLGA scaffolds to biochemical cues resulted in enhanced expression of definitive endoderm markers compared to those differentiated on 2D monolayers. The production of tissue specific cells from stem cells can be scaled up using bioreactor cultures. To apply human stem cell derived islet progenitors in a clinical setting, one must first overcome the problem of immune rejection. Immuno-isolating the cells using microencapsulation provides one possible solution. Coating scaffolds with an anti-inflammatory agent could be an effective means of reducing the inflammatory process that results in pericapsular fibrosis and necrosis of the encapsulated cells. This review summarizes the above issues and describes how 3D scaffolds seeded with stem cells and/or pancreatic progenitors may provide a benefit to achieving normalization of blood glucose levels.

Towards optimising the production of and expression from polycistronic vectors in embryonic stem cells.

Polycistronic vectors linked by self-processing 2A peptides have been successfully used in cellular reprogramming. The expression of these vectors has yet to be well documented in embryonic stem cells. In the present study, we generated expression cassettes containing combinatorial arrangements of 3 pancreatic transcriptions factors (Pdx1, Nkx2.2 and Ngn3) together with an eGFP reporter, all linked by self-processing 2A peptides. The study tested the utility of constructing complex expression cassettes by ligating multiple components, each flanked by unique restriction sites. This approach allowed flexible and efficient design and construction of a combinatorial array of polycistronic constructs, which were expressed after transient transfection into embryonic stem cells. The inclusion of EGFP provided for a convenient proxy measure of expression and showed that expression was similar regardless of EGFP's position within a 2A polycistronic construct. Expression of terminal EGFP was 51% and 24% more efficient when linked by T2A compared to F2A or E2A peptides, respectively. The highest level of expression was achieved when all genes in a construct were linked exclusively by T2A peptides. This effect of T2A was independent of the type of promoter used, as a similar increase in terminal EGFP expression was observed when the polycistronic constructs were under the control of a CAG promoter compared to the CMV promoter, even though the GAG promoter was more efficient in this model than the CMV promoter. The study provides guidance on design strategies and methods for the efficient generation and expression of 2A polycistronic constructs in embryonic stem cells.

Definitive endoderm derived from human embryonic stem cells highly express the integrin receptors alphaV and beta5.

Human embryonic stem cells (hESCs) can be directed to differentiate into a number of endoderm cell types, however mature functional cells have yet to be produced in vitro. This suggests that there may be important factors that have yet to be described, which may be essential for the proper derivation of these cells. One such factor is the integrin mediated interactions between a cell and the extracellular matrix (ECM). On this basis, the present study investigated the role of the ECM in the directed differentiation of hESCs to definitive endoderm via analysis of integrin gene expression. The results showed that definitive endoderm can be efficiently and effectively derived from hESCs in a feeder free, single defined ECM of laminin. Analysis of integrin expression also showed that definitive endoderm highly express the integrins alphaV and beta5, which have the ability to bind to vitronectin, whilst expression of the pluripotency related laminin binding integrins alpha3, alpha6 and beta4 were downregulated. This suggested a potential role of vitronectin binding integrins in the development of definitive endoderm.

Modeling the adhesion of human embryonic stem cells to poly(lactic-co-glycolic acid) surfaces in a 3D environment.

Human embryonic stem cells (hESCs) have previously been cultured on three dimensional (3D) biodegradable polymer scaffolds. Although complex structures were formed from the hESCs, very little is known about the mechanism of adhesion of these cells to the surfaces of the scaffolds. In this study, we achieved the efficient adhesion of pluripotent hESCs to 3D poly(lactic-co-glycolic acid) (PLGA) scaffolds based on our data from a novel two dimensional (2D) model that imitates the surface properties of the scaffolds. In the 2D model, single cell preparations of pluripotent hESCs adhered efficiently and predominantly to PLGA surfaces coated with laminin in comparison to collagen I, collagen IV, or fibronectin-coated surfaces. Flow cytometry analysis revealed that almost all of the pluripotent single cells expressed the integrin alpha 6, with a small percentage also expressing alpha 3ss1, which facilitates adhesion to laminin. This data was then translated into the 3D environment, with the efficient binding of single pluripotent hESCs to PLGA scaffolds coated with laminin. The utility of this system was shown by the directed differentiation of single hESCs seeded within laminin-coated scaffolds toward the endoderm lineage.