FIG. 6.

Microenvironment-mediated intramembraneous vs. endochondral ossification. (A) HA concentration-dependent β-catenin and Runx2 activity indicates that the HA microenvironment may play a role in regulating the two distinct ossification processes. Cells seeded on the PLGA/PLLA scaffolds stained for type II collagen and weakly for type I collagen. The intensity of staining for type I collagen increased in the HA-PLGA/PLLA composite scaffolds (1% and 5%). (B) Stronger type I collagen staining was observed after 8 weeks in all implants along with a detectable amount of osteocalcin. (C) Quantitative analysis of bone formation by hESC-derived mesenchymal cells in the recovered implants. HA-0: PLGA/PLLA scaffold, HA-1: PLGA/PLLA scaffold with 1% w/v HA; HA-5: PLGA/PLLA scaffold with 5% w/v HA. Scale bar=100 μm. Color images available online at www.liebertpub.com/tea