Encapsulation and differentiation of adipose-derived mesenchymal stem cells in a biomimetic purine cross-linked chitosan sponge

Mesenchymal stem cells derived from adipose tissue have become a widely investigated cell source to use in tissue engineering applications. However, an optimal delivery scaffold for these cells is still needed. A rapidly gelling, injectable chitosan sponge was proposed in this study as a potential candidate for a suitable delivery scaffold. The results demonstrated the ability to encapsulate the stem cells at a 97.6% encapsulation efficiency and that the cells maintain their viability within the sponge. With the potential of using this scaffold for bone tissue engineering, ALP activity assay and fluorescent imaging for osteocalcin proved the ability to differentiate the encapsulated cells into the osteogenic lineage. Furthermore, co-encapsulation of pyrophosphatase within the sponge was investigated as a method to overcome the inhibitory effects that the sponge degradation by-products have on mineralization. Alizarin Red S staining demonstrated the beneficial effects of adding pyrophosphatase, where a significant increase in mineralization levels was achieved.