Multi-layered spatial transcriptomics identify secretory factors promoting human hematopoietic stem cell development

Hematopoietic stem cells (HSCs) first emerge in the embryonic aorta-gonad-mesonephros (AGM) region. Studies of model organisms defined intersecting signaling pathways that converge to promote HSC emergence predominantly in the ventral domain of the dorsal aorta. Much less is known about mechanisms driving HSC development in humans. Here, to identify secreted signals underlying human HSC development, we combined spatial transcriptomics analysis of dorsoventral polarized signaling in the aorta with gene expression profiling of sorted cell populations and single cells. Our analysis revealed a subset of aortic endothelial cells with a downregulated arterial signature and a predicted lineage relationship with the emerging HSC/progenitor population. Analysis of the ventrally polarized molecular landscape identified endothelin 1 as an important secreted regulator of human HSC development. The obtained gene expression datasets will inform future studies on mechanisms of HSC development in vivo and on generation of clinically relevant HSCs in vitro

Single cell analysis provides insight into haematopoietic differentiation of human embryonic stem cells

One of the challenges in regenerative medicine remains generating functional haematopoietic stem cells (HSCs) of clinical quantity. Utilizing data from single cell RNA sequencing (scRNA-seq) of human embryonic stem cells (hESC) derived cells, I explored the differences that exist between in vitro and in vivo haematopoiesis, with the aim that understanding these differences could help improve future chances of generating HSCs in vitro. In the first part of this project, functional analysis into in vitro differentiation using an established haematopoietic differentiation protocol, confirmed that the protocol is myeloid and NK lineage biased compared to umbilical cord blood, with the population lineage dynamics changing over time. Using scRNA-seq, I investigated dynamic gene expression of cell populations emerging during hESC differentiation. I show that the haematogenic endothelium capable of generating the haematopoietic progenitors emerges as early as day 6 of differentiation. I also show that priming of the arterial endothelial cells to the haematogenic endothelium, and subsequent emergence of haematopoietic progenitors is associated with an increase in ribosomal and mitochondrial activity. Finally, a comparative analysis of the hESCs generated dataset with publicly available dataset of embryonic haematopoietic tissues revealed that hESC derived haematopoiesis, associated with increased mitochondrial gene activity, is likely mimicking events of the yolk sac haematopoiesis, rather than the haematopoiesis occurring in the AGM region. Based on the findings presented here, I hypothesize that increased mitochondrial activity, likely due to the normoxic culture conditions, may be contributing to the challenge in generating HSCs from hESCs in the dish

Effect of dietary inclusion of garcinia kola dried seed powder on growth performance and immune response of Newcastle disease vaccinated broiler chicks

The effect of dietary inclusion of bitter kola (Garcinia kola) on the performance, organ weight and immune response to Newcastle disease vaccine in broiler chicks was assessed. Forty broiler chicks of five weeks old were randomly assigned into four groups (Groups A, B, C and D) of 12 birds each with the inclusion of sun dried ground bitter kola as a dietary additive at inclusion rate of 0, 5, 10 and 20 g/kg diet in groups A, B, C and D respectively. Birds were weighed weekly and vaccinated at week two with NCDV. Blood samples were collected from six birds in all the groups at weekly interval for PCV determination and serology. Serum samples were assayed for HI antibody using the HA/HI method. Results showed no significant difference (p>0.05) in PCV between groups B, C and D compared to the control A, There was no significant difference (p>0.05) in the weight gain and weight of the visceral organ. On day 14 post vaccination, the result of HI titres showed an increase in the humoral immune response of chicks in the control group when compared to groups B and C. There was a significant increase (p<0.05) in the humoral immune response in group D on day 14 compared with the control group. It can be concluded that bitter kola is well tolerated in broilers and better protected against NCD with bitter kola inclusion in their diet showing higher in the humoral immune response at 20 g/kg diet bitter kola inclusion