Bioprinting with bioactive glass loaded polylactic acid composite and human adipose stem cells

Cellularized scaffolds fabricated with hydrogel do not possess sufficient strength to act as stand-alone implant devices for hard tissue repair and regeneration. A thermoplastic polymer support structure typically provides the structural integrity to scaffolds while cells and growth factors in hydrogel provide biological stimulation for tissue formation. In this research, we investigated the viability of human adipose-derived mesenchymal stem cells (ASCs) mixed in an alginate-gelatin (1:1) hydrogel (bioink) that is deposited between polylactic acid (PLA)-borate glass composite filaments. Bioactive borate glass (13–93B3, also called B3 glass) is a rapidly dissolving biomaterial, and the physiologically relevant ionic dissolution products are known to stimulate cells in vitro and endogenous tissues in vivo. B3 glass was added to PLA in two different weight ratios (50% and 33%) to form PLA ​+ ​B3 glass composites, and the weight loss over time of the 3D printed composite scaffold, pH change of the surrounding media, and mechanical properties were investigated. Physical assessment of the composite scaffolds indicated improved mechanical properties and complete glass dissolution within two weeks. Cellularized scaffolds were bioprinted in three configurations: Bioink only, PLA ​+ ​Bioink, and PLA ​+ ​B3 glass ​+ ​Bioink, and cultured in dynamic conditions to investigate ASC viability. The results indicated a non-uniform cell viability along the scaffold thickness, with hypoxic-like conditions and lower viability at the bottom region to higher viability in the top layers of the scaffold.