Fabrication of Stereotyped Beta-Tricalcium-Phosphate Blocks into a Conjugated Structure using Mesenchymal Stem Cell Sheets Prepared in Temperature-Responsive Culture Dishes

Abstract

To produce a large-sized regenerative joint by the conjugation of small elements combining artificial bone with tissue engineering cartilage, we made small beta tricalcium phosphate (β-TCP)-hexagonal columns (each side: 2 mm, height: 1 cm) as a substitution of subchondral bone, and attempted to achieve mutual bonding of those columns. A large number of cell sheets was produced from mesenchymal stem cells (MSCs) using N-Isopropylacrylamide (NIPPAM)-coated culture dishes. Those cell sheets were dripped onto the lateral surface of a β-TCP-hexagonal column. A pair of the columns was combined side-to-side with each other and were then cultured in osteogenic medium. After 3 weeks of culture, the matrix production-promoting stimulation led to bonding of the two columns, and they were not readily separated by lifting one column using forceps. Not only a pair of those columns, but also three or five, were strongly conjugated, and the columns could be lifted as a single mass. Such in vitro bonding of hexagonal columns of β-TCP utilizing MSCs can support the increase in size of regenerative joints and would enable widening of clinical indications for tissue engineering.