Fibrochondrogenesis in Two Embryonic Stem Cell Lines: Effects of Differentiation Timelines

¹ Department of Bioengineering, Rice University, Houston, Texas; Baylor College of Medicine, Houston, Texas
² Department of Bioengineering, Rice University, Houston, Texas

^* To whom correspondence should be addressed. E-mail: athanasiou{at}rice.edu.

	Abstract

Human embryonic stem cells (hESCs) are an exciting cell source for fibrocartilage engineering. In this study the effects of differentiation time and cell line, H9 versus BG01V, were examined. Embryoid bodies (EBs) were fibrochondrogenically differentiated for 1, 3, or 6 weeks and then used to engineer tissue constructs that were grown 4 additional weeks. Construct matrix was fibrocartilaginous, containing glycosaminoglycans (GAGs) and collagens I, II, and VI. A differentiation time of 3 or 6 weeks produced homogeneous constructs with matrix composition varying greatly with cell line and differentiation time: from 2.6 to 17.4 µg GAG/10⁶ cells and 22.3 to 238.4 µg collagen/10⁶ cells. Differentiation for 1 week resulted in small constructs with poor structural integrity that could not be mechanically tested. The compressive stiffness of the constructs obtained from EBs differentiated for 3 or 6 weeks did not vary significantly as a function of either differentiation time or cell line. In contrast, the tensile properties were markedly greater with the H9 cell line, 1562–1940 kPa versus 32–80 kPa in the BGO1V constructs. These results demonstrate the dramatic effects of hESC cell line and differentiation time on the biochemical and functional properties of tissue engineered constructs, and show progress in fibrocartilage tissue engineering with an exciting new cell source.