P5384Postnatal mouse aorta contains yolk sac-derived haemangioblasts with myeloid and endothelial plasticity and vasculogenic capacity

Background

Macrophages and endothelial cells share an intimate relationship during neovessel formation in different pathophysiological conditions. Recent studies have determined that in some tissues, both cell types are derived embryonically from yolk sac (YS) progenitor cells and are maintained postnatally without contribution from circulating sources. The mechanism by which this local “self-maintenance” occurs is unknown.

Purpose

We previously identified that mouse arteries contain macrophage and endothelial progenitor cells in their adventitial Sca-1+CD45+ compartment. Here we investigated at a clonal level for the existence of postnatal adventitial haemangioblasts and studied their developmental origins.

Methods and results

Single cell digests were prepared from murine aortas to perform colony-forming unit (CFU) assays in methylcellulose. Aortic cells from C57BL/6J mice selectively generated macrophage colonies (CFU-M) which contained progenitor cells that displayed >95% positive for expression of CD45, Sca-1, c-Kit, CX3CR1 and CSF1R, but negative for Lineage markers, as well as mature monocyte/macrophage (CD11b, F4/80) and endothelial (CD144) markers. Secondary replating of CFU-M progenitors from adult aortas revealed their self-renewal capacity, with 1 in 10 cells forming new CFU-M. Lineage mapping using Flt3CrexRosamT/mG mice demonstrated that aortic CFU-M progenitors were FLT3-ve, indicating that they were not derived from definitive bone marrow haematopoiesis. CFU-M prevalence in C57BL/6J aortas was highest in neonatal mice and diminished progressively with increasing age (∼100 per 105 cells at P1, ∼15 at 12w, ∼5 at 52w, P<0.01, n>4/gp), consistent with prenatal seeding. Embryonic profiling determined that CFU-M progenitors first appeared in extra-embryonic yolk sac around E9.5 and in aorta-gonad-mesonephros at E10.5, before the emergence of definitive haematopoietic stem cells. Inducible fate-mapping then confirmed that aortic CFU-M progenitors originated from CX3CR1+ and CSF1R+ cells in E9.5 yolk sac. Both yolk sac and postnatal aortic CFU-M progenitors generated vascular-like networks when cultured in Matrigel in vitro, containing M2-like macrophages (CD11b+F4/80+CD206+) and endothelial cells (CD31+CD144+). They produced similar progeny and rescued adventitial vascular sprouting when seeded around aortic rings whose adventitia had been stripped. Finally, adoptive transfer of CFU-M progenitors into a mouse model of hindlimb ischaemia resulted in 80% augmentation in hindlimb perfusion compared to cell-free control, with de novo transformation of donor cells into macrophages, endothelial cells and perfused neovessels (n=6).

Conclusion

To the best of our knowledge, this is the first ever definitive proof at a clonal level for the existence of haemangioblasts in postnatal tissue. Adventitial haemangioblasts originate from extra-embryonic YS and are a source of vasculogenesis in the arterial wall, relevant to vasa vasorum formation.

Acknowledgement/Funding

NHMRC of Australia (GNT1086796, CDF1161506), NHFA (FLF100412, FLF102056) Royal Australasian College of Physicians

The Source of the Problem

The portable chest x-ray (Figure 1) shows a widened cardiac silhouette. An endotracheal tube is in situ, indicating the patient is now intubated. The ECG (Figure 2) shows sinus rhythm with widespread mixed convex and concave ST elevation, most notable in V4, V5 and the lateral leads. There is a suggestion of PR depression in the inferior leads.

The Source of the Problem

A 58-year-old lady presented to the Emergency Department with a two-day history of shortness of breath and confusion, on a background of one week's history of general malaise, vomiting, fevers and chills. Her past medical history was unremarkable except for a large, benign goitre. Systemic enquiry revealed no symptoms to suggest a focus of infection.

A national study of the unmet needs of support persons of haematological cancer survivors in rural and urban areas of Australia

Purpose

This study aimed to compare support persons of haematological cancer survivors living in rural and urban areas in regard to the type, prevalence and factors associated with reporting unmet needs.

Methods

One thousand and four (792 urban and 193 rural) support persons of adults diagnosed with haematological cancer were recruited from five Australian state population-based cancer registries. Participants completed the Support Person Unmet Needs Survey (SPUNS) that assessed the level of unmet needs experienced over the past month across six domains.

Results

Overall, 66% of support persons had at least one ‘moderate, high or very high’ unmet need and 24% (n = 182) reported having multiple (i.e. 6 or more) ‘high/very high’ unmet needs in the past month. There were no significant differences between rural and urban support persons in the prevalence of multiple unmet needs or mean total unmet needs scores. There were however significant differences in the types of ‘high/very high’ unmet needs with support persons living in rural areas more likely to report finance-related unmet needs. Support persons who indicated they had difficulty paying bills had significantly higher odds of reporting multiple ‘high/very high’ unmet needs.

Conclusions

This is the first large, population-based study to compare the unmet needs of support persons of haematological cancer survivors living in rural and urban areas. Findings confirm previous evidence that supporting a person diagnosed with haematological cancer correlates with a high level of unmet needs and highlight the importance of developing systemic strategies for assisting support persons, especially in regard to making financial assistance and travel subsidies known and readily accessible to those living in rural areas.

An unusual case of dysphagia

A 51-year-old lady, with a background of an arachnoid cyst and ventriculo-peritoneal shunt in situ, presented to the Acute Medical Unit with a 2-day history of neck pain. She awoke from sleep with the pain and it persisted since. She had not been involved in any trauma, had no previous history of neck or back pain and her pain was not controlled with simple analgesia. She also complained of new odynophagia and high dysphagia, particularly to solid foods. There was no history of upper respiratory tract infection.