Fabrication of endothelialized tube in collagen gel as starting point for self-developing capillary-like network to construct three-dimensional organs in vitro

A possible strategy for creating three-dimensional (3D) tissue-engineered organs in vitro with similar volumes to the primary organs is to develop a capillary network throughout the constructs to provide sufficient oxygenation and nutrition to the cells composing them. Here, we propose a novel approach for the creation of a capillary-like network in vitro, based on the spontaneous tube-forming activity of vascular endothelial cells (ECs) in collagen gel. We fabricated a linear tube of 500 microm in diameter, the inner surface of which was filled with bovine carotid artery vascular endothelial cells (BECs), in type I collagen gel as a starting point for the formation of a capillary-like network. The BECs exposed to a medium containing vascular endothelial growth factor (VEGF) migrated into the ambient gel around the tube. After 2 weeks of VEGF exposure, the distance of the migration into the ambient gel in the radial direction of the tube reached approximately 800 microm. Cross-sections of capillary-like structures composed of the migrating BECs, with a lumen-like interior space, were observed in slices of the gel around the tube stained with hematoxylin-eosin (H&E). These results demonstrate that this approach using a pre-established tube, which is composed of ECs, as a starting point for a self-developing capillary-like network is potentially useful for constructing 3D organs in vitro.     

Cancer stem cell marker‐expressing cell‐rich spheroid fabrication from PANC‐1 cells using alginate microcapsules with spherical cavities templated by gelatin microparticles

Cancer stem‐like cells (CSCs) are rare subpopulations of cancer cells. The development of three‐dimensional tissues abundant in CSCs is important to both the understanding and establishment of novel therapeutics targeting them. Here, we describe the fabrication of multicellular tumor spheroids (MTSs) abundant in CSCs by employing alginate microcapsules with spherical cavities templated by cell‐enclosing gelatin microparticles. Encapsulated human pancreatic cancer cell line PANC‐1 cells grew for 14 days until they filled the cavities. The percentage of cells expressing reported CSC markers CD24, CD44, and epithelial‐specific antigen (ESA), increased during this growth period. The percentage at 24 days of incubation, 22%, was 1.6 times higher than that of MTSs formed on a nonadherent surface in the same period of incubation. The MTSs in microcapsules could be cryopreserved in liquid nitrogen using a conventional method. No significant difference in the content of CSC marker‐expressing cells was detected at 3 days of incubation when thawed after cryopreservation for 2 weeks, compared with cells incubated without prior cryopreservation. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1071–1076, 2015     

The innate immune system in the intestine

The innate immune system provides the first line of host defense against invading pathogens. Innate immune responses are initiated by germline-encoded PRR, which recognize specific structures expressed by microorganisms. TLR are a family of PRR which sense a wide range of microorganisms, including bacteria, fungi, protozoa and viruses. TLR are also expressed in the intestine and are critical for intestinal homeostasis. Recently, cytoplasmic PRR, such as NLR and RLR, have been shown to detect pathogens that have invaded the cytosol. One of the NLR, NOD2, is thought to be involved in the pathogenesis of Crohn's disease. This review focuses on the innate immune responses triggered by PRR in the intestine.