Fig. 2.

Alterations of the 3D self-organized VMC multicellular structure by Noggin. The multicellular structures were composed of aggregates of VMCs from thin networks (a) to thicker networks (d) (Day 11). a, b showed the experimental 3D multicellular structure without exogenous factors. d, e showed the experimental 3D multicellular structure treated by Noggin that was increased gradually from 0.25 to 0.9 μg/mL over the first 6 days and maintained at 0.9 μg/mL for the following days. b and (e) represented higher magnifications of (a) and (d), respectively. The multicellular structures were visualized by SPIM after F-actin staining with Alexa Fluor 488 phalloidin, which outlines the cellular skeletons. The conditions for VMC-HA hydrogel were 3.5% HA, 100 μM RGD, and initial cell density of 7,500/μL. c and (f) were the corresponding simulated 3D morphologies for (b) and (e), respectively. Regions of high cell concentrations were marked in red. The computational simulations showed the conversion from (c) a thin network structure (D = 0.005, q = 0.004, χ = 0.09, U _EX = 0, V _EX = 0), to (f) an aggregated thick network structure (D = 0.005, q = 0.006, χ = 0.09, a = 0.001, U _EX = 0, V _EX = 0)