An important step towards a prevascularized islet macroencapsulation device—effect of micropatterned membranes on development of endothelial cell network

Abstract

The development of immune protective islet encapsulation devices could allow for islet transplantation in the absence of immunosuppression. However, the immune protective membrane / barrier introduced there could also impose limitations in transport of oxygen and nutrients to the encapsulated cells resulting to limited islet viability. In the last years, it is well understood that achieving prevascularization of the device in vitro could facilitate its connection to the host vasculature after implantation, and therefore could provide sufficient blood supply and oxygenation to the encapsulated islets. However, the microvascular networks created in vitro need to mimic well the highly organized vasculature of the native tissue. In earlier study, we developed a functional macroencapsulation device consisting of two polyethersulfone/polyvinylpyrrolidone (PES/PVP) membranes, where a bottom microwell membrane provides good separation of encapsulated islets and the top flat membrane acts as a lid. In this work, we investigate the possibility of creating early microvascular networks on the lid of this device by combining novel membrane microfabrication with co-culture of human umbilical vein endothelial cell (HUVEC) and fibroblasts. We create thin porous microstructured PES/PVP membranes with solid and intermittent line-patterns and investigate the effect of cell alignment and cell interconnectivity as a first step towards the development of a stable prevascularized layer in vitro. Our results show that, in contrast to non-patterned membranes where HUVECs form unorganized HUVEC branch-like structures, for the micropatterned membranes, we can achieve cell alignment and the co-culture of HUVECs on a monolayer of fibroblasts attached on the membranes with intermittent line-pattern allows for the creation of HUVEC branch-like structures over the membrane surface. This important step towards creating early microvascular networks was achieved without the addition of hydrogels, often used in angiogenesis assays, as gels could block the pores of the membrane and limit the transport properties of the islet encapsulation device.

Controlled Heterotypic Pseudo-Islet Assembly of Human β-Cells and Human Umbilical Vein Endothelial Cells Using Magnetic Levitation

“…Recreating the pancreatic niche by the combination of ECs and pancreatic b-cells may contribute to graft survival in vitro. 42 Apart from improved graft survival 13,22 and prevascularization, 43 the coculture of b-cells with ECs provides beneficial effects on b-cell functionality. 10,18,27 However, these stimulatory capabilities of ECs on b-cells have not been shown to exist in a human-only cell line-based in vitro model.…”

“…One limitation could be that HUVECs are not an ideal cell source to mimic vascular ECs in combination with the human b-cell line EndoC-bH3, although HUVECs have been widely used and established to model ECs behavior. 5,18,25,27,43,[45][46][47][48] Dissimilarities upon cytotoxic reagents or in cytoarchitecture of islets have been previously described, underlining major differences between human and rodent pancreatic islets, which limits the possibility to extrapolate from results obtained in rodent systems to the human ones. 29,49 Since b-cells rely on an highly specialized environment, 15 a human cell line-based in vitro test system might require particularly specialized ECs to properly model the interaction between b-cells and ECs, such as human pancreatic microvascular ECs or ductal epithelial cells (DECs).…”

Construction of higher-order cellular microstructures by a self-wrapping co-culture strategy using a redox-responsive hydrogel

“…As demonstrated, the cell sheet was capable of wrapping other cells, and thus the cellular Furoshiki should provide an alternative approach for constructing complex, higher-order cellular microstructures. Although the main focus of this study is to investigate the potential of a confluent cell monolayer in a self-wrapping co-culture technique, we envisioned a possible application of the cellular Furoshiki either in the development of in vitro disease model for the drug screening application 3,72,73 and or the tissue engineering for the prevention of the rejection of immunosuppression in transplantation [74][75][76] .…”

Atorvastatin reverses the dysfunction of human umbilical vein endothelial cells induced by angiotensin II

“…HUVECs are the most widely used cell type used for studying vasculature and angiogenesis (28)(29)(30). Excessive damage to HUVECs may influence their biological function (31).…”