Blastocyst-Inspired Hydrogels to Maintain Undifferentiation of Mouse Embryonic Stem Cells

Abstract

Stem cell fate is determined by specific niches that provide multiple physical, chemical, and biological cues. However, the hierarchy or cascade of impact of these cues remains elusive due to their spatiotemporal complexity. Here, anisotropic silk protein nanofiber-based hydrogels with suitable cell adhesion capacity are developed to mimic the physical microenvironment inside the blastocele. The hydrogels enable mouse embryonic stem cells (mESCs) to maintain stemness in vitro in the absence of both leukemia inhibitory factor (LIF) and mouse embryonic fibroblasts (MEFs), two critical factors in the standard protocol for mESC maintenance. The mESCs on hydrogels can achieve superior pluripotency, genetic stability, developmental capacity, and germline transmission to those cultured with the standard protocol. Such biomaterials establish an improved dynamic niche through stimulating the secretion of autocrine factors and are sufficient to maintain the pluripotency and propagation of ESCs. The mESCs on hydrogels are distinct in their expression profiles and more resemble ESCs in vivo. The physical cues can thus initiate a self-sustaining stemness-maintaining program. In addition to providing a relatively simple and low-cost option for expansion and utility of ESCs in biological research and therapeutic applications, this biomimetic material helps gain more insights into the underpinnings of early mammalian embryogenesis.

Engineered Tough Silk Hydrogels through Assembling β-Sheet Rich Nanofibers Based on a Solvent Replacement Strategy

“…Compared to BSNF2, the hydrogels prepared via solvent replacement showed improved cytocompatibility. The rich negative charge of the nanofibers in BSNF2 hydrogels (zeta potential ∼ −50 mV) as well as the inferior mechanical performances limited adhesion and spreading of the BMSCs on these hydrogels. − However, BMSCs spread well on the tougher hydrogels and maintained the improved proliferation over 7 days (Figure ). More cells adhered to the stiffest hydrogel (BSNF20) at day 1 and had a significantly larger spread area.…”

Silk Fibroin-Based Tough Hydrogels with Strong Underwater Adhesion for Fast Hemostasis and Wound Sealing

“…The hydrogel consists of two major biomacromolecules: methacrylate-functionalized silk fibroin (named SFMA) and catechol-conjugated hyaluronic acid (named HACA). Silk fibroin (SF) is an appealing biopolymer derived from Bombyx mori cocoons. − The primary amines of SF were easily functionalized by glycidyl methacrylate (GMA), providing a fast ultraviolet (UV) photo-crosslinking gelation within 5 s. Meanwhile, photo-crosslinking reaction triggered the formation of crystalline β-sheet structure in SF. Hyaluronic acid (HA) is a glycosaminoglycan polymer derived from the extracellular matrix. − The dopamine molecules were conjugated onto HA backbone to yield the catechol-containing polymer, thereby providing the interfacial adhesion behavior in water.…”

Regulation of stem cell fate and function by using bioactive materials with nanoarchitectonics for regenerative medicine

“…The underlying mechanisms can be explained by releasing Zn 2+ from the ZnO NRs and stimulated KLF4, a Zn 2+ -binding gene, which lead to up-regulated NANOG and OCT4. Simulating the niche inside the blastocele, Hang et al designed an anisotropic silk protein nanofiber-based hydrogel, which is capable of maintain mESCs’ pluripotency in the absence of LIF and MEFs [ 136 ]. Furthermore, the biomaterials establish a sustainable stemness-maintaining microenvironment through stimulating the secretion of autocrine cytokines.…”