An estradiol releasing, proangiogenic hydrogel as a candidate material for use in soft tissue interposition

The Microcirculation of Vaginal Tissue in Women with Obstetric Vesicovaginal Fistula and Short-Term Effects of Surgical Repair on Microvascular Parameters

OBJECTIVES

The objective of the study was to better understand the extent of the ischemic trauma and the effects of surgical repair on the vaginal microcirculation in patients with obstetric vesicovaginal fistula (VVF).

DESIGN

In this observational study, we evaluated the vaginal microvasculature surrounding VVF using handheld vital microscopy (HVM) before, during, and 2 weeks after surgical VVF repair.

PARTICIPANTS

Seventeen women undergoing VVF repair were included in this study.

SETTING

The study was conducted in the Fistula Care Centre in Lilongwe, Malawi.

METHODS

We used HVM with incident dark-field imaging to non-invasively visualize the microvasculature of the vaginal tissue surrounding fistulas. The primary outcome was the presence of microvascular flow. Secondary outcomes included angioarchitecture, fistula closure (postoperative dye test), and urinary continence (pad weight test).

RESULTS

Microvascular flow was present before, during, and after surgical repair in, respectively, 83.8%, 83.9%, and 93.4% of obtained image sequences. The angioarchitecture was normal in 75.8% of the image sequences before surgery, 69.4% at fistula closure, and 89.1% two weeks after VVF repair. Fourteen (82.4%) patients had a closed fistula after surgical repair.

LIMITATIONS

The study was limited by the lack of a control group and the relatively small sample size.

CONCLUSION

Although the vaginal microcirculation in women with VVF is compromised, extensive ischemic damage is not observed in the tissue surrounding fistulas. This suggests significant regenerative capacity of the vaginal vasculature in young women, or less extensive ischemic damage than presumed. Following surgical repair, we observed improvement of microcirculatory flow and angioarchitecture, suggesting that surgery is a good option for patients with obstetric VVF.

Microvascular Experimentation in the Chick Chorioallantoic Membrane as a Model for Screening Angiogenic Agents including from Gene-Modified Cells

The chick chorioallantoic membrane (CAM) assay model of angiogenesis has been highlighted as a relatively quick, low cost and effective model for the study of pro-angiogenic and anti-angiogenic factors. The chick CAM is a highly vascularised extraembryonic membrane which functions for gas exchange, nutrient exchange and waste removal for the growing chick embryo. It is beneficial as it can function as a treatment screening tool, which bridges the gap between cell based in vitro studies and in vivo animal experimentation. In this review, we explore the benefits and drawbacks of the CAM assay to study microcirculation, by the investigation of each distinct stage of the CAM assay procedure, including cultivation techniques, treatment applications and methods of determining an angiogenic response using this assay. We detail the angiogenic effect of treatments, including drugs, metabolites, genes and cells used in conjunction with the CAM assay, while also highlighting the testing of genetically modified cells. We also present a detailed exploration of the advantages and limitations of different CAM analysis techniques, including visual assessment, histological and molecular analysis along with vascular casting methods and live blood flow observations.

Simulation of the process of angiogenesis: Quantification and assessment of vascular patterning in the chicken chorioallantoic membrane

Angiogenesis, the formation of new blood vessels from pre-existing ones, begins during embryonic development and continues throughout life. Sprouting angiogenesis is a well-defined process, being mainly influenced by vascular endothelial growth factor (VEGF). In this study, we propose a meshless-based model capable of mimicking the angiogenic response to several VEGF concentrations. In this model, endothelial cells migrate according to a diffusion-reaction equation, following the VEGF gradient concentration. The chick chorioallantoic membrane (CAM) assay was used to model the branching process and to validate the obtained numerical results. To analyse the angiogenic response, the total vessel number and the total vessel length presented in the CAM images and in the simulations for all the VEGF concentrations tested were quantified. In both the CAM assay and simulation, the treatments with VEGF increased the total vessel number and the total vessel length. The obtained quantitative results were very similar between the two methodologies used. The proposed model accurately simulates the capillary network pattern concerning its structure and morphology, for the lowest VEGF concentration tested. For the highest VEGF concentration, the capillary network predicted by the model was less accurate when compared to the one presented in the CAM assay but this may be explained by changes in blood vessel width at higher VEGF concentrations. This remains to be tested.