Living Bacterial Sacrificial Porogens to Engineer Decellularized Porous Scaffolds

Abstract

Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types.

Prediction and control of number of cells in microdroplets by stochastic modeling

“…We have used this ejector to eject droplets encapsulating various cell types (e.g., smooth muscle cells (SMCs), embryonic stem cells, cancer cells) with high cell viability 14, 15, 17, 19, 30 , Figure 1. The cell encapsulation systems involve in general formation of a breaking droplet that encapsulates cells within the contents.…”

“…Recently, cell encapsulation in microdroplets has found new fields of applications including microfluidics 6, 7 , cryobiology 3, 8–11 , clinical diagnostics 12 , cell patterning 3, 13–16 , tissue engineering 13, 17 , high throughput drug studies for cancer 15 , stem cells 18, 19 , and pharmaceutical research 20 . These applications require control over the number of cells encapsulated within individual droplets.…”

Nanostructured substrates for isolation of circulating tumor cells

“…Examples of such surfaces include random nanofibers, nanopits and nanogrooves. Nanostructured substrates are also employed in tissue engineering for better understanding of mammalian cell adhesion mechanisms and for the restoration of function to damaged tissues [33,43,62,65–70]. Nanostructures facilitate protein (such as fibronectin and vitronectin) adherence to surfaces due to a larger surface area [71].…”

Emerging Technologies for Assembly of Microscale Hydrogels

“…Microdroplet technologies based on bioprinting can be used to generate cell encapsulating microscale hydrogel droplets that can be assembled to form 3D complex constructs 14, 19, 44, 78, 87, 102, 106. Bioprinting technologies have been developed to spatially control organization of cells in combination with scaffolding materials 44, 58, 102, 103, 106. Today's bioprinting technologies, inkjet,88, 90 laser,64, 91 and bio‐electrosprays92, 93 were not specifically designed to generate droplets encapsulating living cells 14.…”