In vitro generation of functional murine heart organoids via FGF4 and extracellular matrix.

Our understanding of the spatiotemporal regulation of cardiogenesis is hindered by the difficulties in modeling this complex organ currently by in vitro models. Here we develop a method to generate heart organoids from mouse embryonic stem cell-derived embryoid bodies. Consecutive morphological changes proceed in a self-organizing manner in the presence of the laminin-entactin (LN/ET) complex and fibroblast growth factor 4 (FGF4), and the resulting in vitro heart organoid possesses atrium- and ventricle-like parts containing cardiac muscle, conducting tissues, smooth muscle and endothelial cells that exhibited myocardial contraction and action potentials. The heart organoids exhibit ultrastructural, histochemical and gene expression characteristics of considerable similarity to those of developmental hearts in vivo. Our results demonstrate that this method not only provides a biomimetic model of the developing heart-like structure with simplified differentiation protocol, but also represents a promising research tool with a broad range of applications, including drug testing.

Utility of a rotation/revolution-type agitator for chondrocyte isolation during preparation of engineered cartilage.

During the manufacture of cell- and tissue-based products, such as engineered cartilage for autologous chondrocyte implantation, maximizing the number of cells isolated from donor tissue substantially improves the productivity of these products. The method used for agitating tissues with digestive fluid and enzymes can considerably affect both the quality and quantity of isolated cells. This study aimed to investigate the effectiveness of a rotation/revolution-type agitator for chondrocyte isolation following the enzymatic digestion of rat costal cartilage. Cartilage tissue cut into 1 mm3-thick sections was equally divided between two groups and placed in 50-mL conical tubes; sections in both groups were digested using 0.1 mg/mL liberase TH (collagenase/thermolysin) at 37 °C for 4 h with either rotation/revolution or conventional orbital agitation method. Compared with using conventional orbital agitator, using the rotation/revolution-type agitator resulted in a significant (>two-fold) increase in the number of isolated cells. In subsequent primary cultures, chondrocytes obtained by rotation/revolution agitation showed superior initial attachment to tissue culture dish on day 1 and 2 compared with those obtained by conventional agitation; however, no differences in cell proliferation or cartilage-related molecule expression patterns were observed between cells derived from either method after 3 days of subculture. These findings suggested that there are no disadvantages to the proposed rotation/revolution agitation method. Rotation/revolution-type agitators are a promising apparatus for preparing chondrocytes for primary cultures and cartilage tissue engineering.

Characterization of poly(L-glutamic acid)-grafted hyaluronan as a novel candidate medicine and biomedical device for intra-articular injection.

A novel hyaluronan (HA) derivative, poly(L-glutamic acid)-grafted hyaluronan (PGA-g-HA), was synthesized to improve the durability of conventional HA products for intra-articular injection. The purpose of this study was to investigate the characteristics of the novel HA derivative in terms of viscoelasticity, degradation behavior, non-immunogenicity, and bioactivity using preliminary in vitro and in vivo experiments. The storage modulus (G') and loss modulus (G″) of PGA-g-HA were similar to those of HA80 (approximately 8.0 × 105 Da) rather than those of original HA200 (approximately 2.0 × 106 Da). PGA-g-HA showed strong resistance against hyaluronidase hydrolysis compared to unmodified HA200. The immunogenicity resulting from grafting PGA to HA200 was not detected in bone marrow derived dendritic cells. The anti-inflammatory activity of PGA-g-HA was confirmed in IL-1ß-stimulated chondrocytes. In addition, compared to unmodified HA200, the intra-articular injection of PGA-g-HA produced greater chondroprotective effects on a monoiodoacetic acid-induced model of rat knee osteoarthritis at two weeks after a single treatment. Therefore, PGA-g-HA is expected to be a promising medicine and biomedical device for intra-articular injection. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3006-3016, 2017.