Effect of Substrate Stiffness on Early Mouse Embryo Development

Abstract

It is becoming increasingly clear that cells are remarkably sensitive to the biophysical cues of their microenvironment and that these cues play a significant role in influencing their behaviors. In this study, we investigated whether the early pre-implantation embryo is sensitive to mechanical cues, i.e. the elasticity of the culture environment. To test this, we have developed a new embryo culture system where the mechanical properties of the embryonic environment can be precisely defined. The contemporary standard environment for embryo culture is the polystyrene petri dish (PD), which has a stiffness (1 GPa) that is six orders of magnitude greater than the uterine epithelium (1 kPa). To approximate more closely the mechanical aspects of the in vivo uterine environment we used polydimethyl-siloxane (PDMS) or fabricated 3D type I collagen gels (1 kPa stiffness, Col-1k group). Mouse embryo development on alternate substrates was compared to that seen on the petri dish; percent development, hatching frequency, and cell number were observed. Our results indicated that embryos are sensitive to the mechanical environment on which they are cultured. Embryos cultured on Col-1k showed a significantly greater frequency of development to 2-cell (68±15% vs. 59±18%), blastocyst (64±9.1% vs. 50±18%) and hatching blastocyst stages (54±25% vs. 21±16%) and an increase in the number of trophectodermal cell (TE,65±13 vs. 49±12 cells) compared to control embryos cultured in PD (mean±S.D.; p<.01). Embryos cultured on Col-1k and PD were transferred to recipient females and observed on embryonic day 12.5. Both groups had the same number of fetuses, however the placentas of the Col-1k fetuses were larger than controls, suggesting a continued effect of the preimplantation environment. In summary, characteristics of the preimplantation microenvironment affect pre- and post-implantation growth.

Ultrafast and Wide Range Analysis of DNA Molecules Using Rigid Network Structure of Solid Nanowires

“…One major difference between the present rigid network structure and the conventional gels is the stiffness of the network structures. The present network structure is much more rigid than the conventional gel network structures43; for example, typically the Young's modulus of agarose gel is 0.1–1 MPa, whereas that of the solid nanowires is 100 ± 20 GPa4445. Since the deformation of DNA molecules must be larger when softer DNA molecules collide with a stiffer object, collision with the rigid nanowire network structure must amplify the DNA deformation more than for the soft gel, considering the stiffness of the DNA molecules.…”

Validation of Reliable Reference Genes for Real-Time PCR in Human Umbilical Vein Endothelial Cells on Substrates with Different Stiffness

“…For example, mechanical microenvironments may regulate cellular functions relevant to development, homeostasis, and disease [1]–[3]. Many mainly pathological conditions, including aortic stiffness and liver fibrosis, result in significant mechanical changes at the whole organ, regional, and cellular levels [3]–[5].…”

Self-assembled Nanowire Arrays as Three-dimensional Nanopores for Filtration of DNA Molecules

“…The SnO2/SiO2 nanowire core/shell, which forms the hard gel-like 3D nanopore structure, 16 has a rigidity (Young's modulus ≈ 100 GPa) 22 that is higher than that of agarose gel or poly acrylamide gel (Young's modulus ≈ 0.1 -1 MPa). 23 The biomolecules migrate in the rigid network as if they were in a free solution environment, whereas the biomolecule migration in a soft material network is hindered by the elasticity of the matrix material. However, the scenarios based on differences of the DNA gyration radius and the DNA electrophoretic mobility, as well as the stiffness of the 3D nanopores structure cannot clearly explain the present results.…”