Biology subjects

Salehi-Nik, N.

Publications and source records attributed to Salehi-Nik, N..

3 recordsLinked to original sources

bioRxiv2024

Shape that matters: Yolk geometry spatially modulates developing vascular networks within chick chorioallantoic membrane

Controlling the multiscale organization of vasculature within diverse geometries is essential for shaping tissue-specific and organ-specific architectures. Nevertheless, how geometrical characteristics of surrounding tissues influence vessel morphology and blood flow remains unclear. Where the regulation of vascular organization by mechanical signals associated with fluid flow is well known, this study postulates that the organization of developing vasculature can also be regulated by mechanical signals connected to the confinement and thus the deformation of surrounding tissues. To test the Shape-Induced Vascular Adaptation (SIVA) concept, fertilized chicken egg contents containing developing vasculature were cultured within engineered eggshell platforms of different shapes. Our findings demonstrate that the vascularized chick chorioallantoic membrane (CAM) adapts to the shape of engineered eggshell, long before reaching its boundaries. This adaptation affects the organization of the vascular network within the CAM, affecting parameters such as vessel area, branching, orientation, length, diameter and endpoints. Specifically, we observed that sharp corners in the engineered eggshell led to more elongated vascular structures. To further explore the dynamic nature of this phenomenon, a proof-of-concept experiment was performed using a shape-shifting engineered eggshell that deforms the egg content from circle to square shape. Using this shape-shifting prototype, we observed a direct effect of eggshell deformation on the vessel morphology and flow dynamics in a time-dependent manner. Overall, our exovo experimental platform provides a unique opportunity to study how mechanical stimuli such as shape influence the spatial and temporal organization of developing vascularized tissues. By subjecting these tissues to various static and dynamic conditions, we induced both local and global changes in their organization. This class of perturbation provides us with an additional tool which can be used for shaping vascular organization within developing tissues and to engineer tissues with geometrically tunable vessel structures.

bioengineering↗

bioRxiv2024

Switching to external flows: perturbations of developing vasculature within chicken chorioallantoic membrane

The impact of fluid flow shear stresses, generated by the movement of blood through vasculature, on the organization and maturation of vessels is widely recognized. Nevertheless, it remains uncertain whether external fluid flows outside of the vasculature in the surrounding tissue can similarly play a role in governing these processes. In this research, we introduce an innovative technique called superfusion-induced vascular steering (SIVS). SIVS involves the controlled imposition of external fluid flow patterns onto the vascularized chick chorioallantoic membrane (CAM), allowing us to observe how this impacts the organization of vascular networks. To investigate the concept of SIVS, we conducted superfusion experiments on the intact chick CAM cultured within engineered eggshell system, using phosphate buffered saline (PBS). To capture and analyze the effects of superfusion, we employed a custom-built microscopy setup, enabling us to image both superfused and non-superfused regions within the developing CAM. This study provides valuable insights into the practical application of fluid superfusion within an in vivo context, shedding light on its significance for understanding tissue development and manipulation in an engineering setting.

bioengineering↗

bioRxiv2020

Aptamer based spatiotemporally controlled growth factor patterning for tunable local microvascular network formation in engineered tissues

Spatiotemporally controlled growth factor availability is of crucial importance for achieving hierarchically organized vascular network formation within engineering tissues. Even though current growth factor delivery systems can provide sustained release and growth factor delivery on demand, they generally do not facilitate temporal control over the release rates and thus adaptation in accordance with the needs of growing engineered tissue. Additionally, with conventional growth factor loading methods, growth factors are often subjected to organic solvents or harsh conditions, leading to lower bioactivity and denaturation of the proteins. To overcome these limitations, this manuscript reports on the development of VEGF specific 5 acrydite modified aptamer functionalized GelMA hydrogels. The covalently incorporated aptamers can selectively bind to proteins with high affinity and specificity, and can thus sequester the target protein from the surrounding environment. The manuscript shows that this not only provides temporal control over the growth factor release via complementary sequence hybridization, but also enables local control of microvascular network formation in 3D.

bioengineering↗