No abstract

Direct-write printing of stem cells within biomaterials presents an opportunity to engineer tissue for in vitro modeling and regenerative medicine. Here, a first example of constructing neural tissue by printing human neural stem cells that are differentiated in situ to functional neurons and supporting neuroglia is reported. The supporting biomaterial incorporates a novel clinically relevant polysaccharide-based bioink comprising alginate, carboxymethyl-chitosan, and agarose. The printed bioink rapidly gels by stable cross-linking to form a porous 3D scaffold encapsulating stem cells for in situ expansion and differentiation. Differentiated neurons form synaptic contacts, establish networks, are spontaneously active, show a bicuculline-induced increased calcium response, and are predominantly gamma-aminobutyric acid expressing. The 3D tissues will facilitate investigation of human neural development, function, and disease, and may be adaptable for engineering other 3D tissues from different stem cell types.

No abstract

Niche-derived factors regulate tissue stem cells, but apart from the mechanosensory pathways, the effect of niche geometry is not well understood. We used organoids and bioengineered tissue culture platforms to demonstrate that the conical shape of Lgr5 + small intestinal stem cells (ISCs) facilitate their self-renewal and function. Inhibition of non-muscle myosin II (NM II)–driven apical constriction altered ISC shape and reduced niche curvature and stem cell capacity. Niche curvature is decreased in aged mice, suggesting that suboptimal interactions between old ISCs and their niche develop with age. We show that activation of NM IIC or physical restriction to young topology improves in vitro regeneration by old epithelium. We propose that the increase in lateral surface area of ISCs induced by apical constriction promotes interactions between neighboring cells, and the curved topology of the intestinal niche has evolved to maximize signaling between ISCs and neighboring cells.

The beneficial effects of electrical stimulation (ES) on human cells in vitro and in vivo have long been known. Although the effects of stimulation are clear and the therapeutic benefits are known, no uniform parameters exist with regard to the duration, frequency and amplitude of the ES. To this end, we are answering several important questions on the parameters for ES of nerve and muscle monocultures and co-cultures by probing the effects on the enhancement of acetylcholine receptors (AChR) clustering available for neuromuscular junction formation using a conductive platform. This work opens the possibility to combine electrical stimulus delivered via conductive polymer substrates, from which biomolecules could also be delivered, providing opportunities to further enhance the therapeutic effect.

No abstract

On page 1429 G. G. Wallace, J. M. Crook, and co‐workers report the first example of fabricating neural tissue by 3D bioprinting human neural stem cells. A novel polysaccharide based bioink preserves stem cell viability and function within the printed construct, enabling self‐renewal and differentiation to neurons and supporting neuroglia. Neurons are predominantly GABAergic, establish networks, are spontaneously active, and show a bicuculline induced increased calcium response.

Estrogen has been shown to protect women against colorectal cancer (CRC). In this study, using tissue-specific knockout mice, we characterize the role for intestinal estrogen receptor beta (ERβ) and, for the first time, demonstrate a direct preventive role against colitis-induced colon tumors in both sexes. By inducing colitis and CRC using azoxymethane and dextran sodium sulfate in intestine-specific ERβ knockout mice, we observe an increase in colon ulceration in addition to an enhanced development of neoplasms, with increased number of tumors in males and increased tumor size in females. We identify a local increase in TNFα expression and deregulation of NFκB targets. We note that males exhibit especially strong effects following intestinal ERβ knockout. The protection by intestinal ERβ against TNFα-induced damage is corroborated using ex vivo organoid culture, where we observe that activation of ERβ protects against TNFα-induced epithelial cell damage. Further, we characterize an underlying mechanism of action, using CRC cell lines with re-introduced ERβ, where ERβ binds to cis-regulatory chromatin areas of key NFκB regulators BCL3, BIRC3 and ATF3, and thereby modulates TNFα-induced signaling. With these results we define a clear role for intestinal ERβ and demonstrate an underlying mechanism, strongly supporting the notion that selective activation of intestinal ERβ has potential to prevent CRC in both sexes. Citation Format: Linnea Hases, Rajitha Indukuri, Madeleine Birgersson, Trang Nguyen-Vu, Rodrigo Lozano, Ashish Saxena, Johan Hartman, Jonna Frasor, Jan-Åke Gustafsson, Pekka Katajisto, Amena Archer, Cecilia Williams. Intestinal estrogen receptor beta suppresses colon inflammation and tumorigenesis in both sexes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2081.