Page 354 - AWSAR 2.0

330 || AWSAR Awarded Popular Science Stories - 2019
looking up at someone’s clothes, for example, kids going to school have a uniform and kids from different schools can be identified from their uniforms. Similarly, the cells in our body perform different functions
and have different levels of proteins expressed on their surfaces. These proteins help us in identifying and studying the cell’s functions and growth conditions in laboratories.
To see if our beads were
helping in differentiating stem
cells, we allowed the stem
cells to grow inside beads
for 14 days. The Alg-silk
beads showed formation of
chondrocyte like cells, which
was confirmed by presence of
Collagen-2 proteins found in
cartilage. The Alg- PO4-silk beads showed formation of bone like cells as they expressed Osteocalcin protein. These results were further confirmed by quantifying the expression of respective genes.
While, the functional groups were shown to help in differentiation of stem cells on 2D silk films in our previous work, the time period was drastically reduced from 60 days for 2D silk films to 14 days, in 3D beads. The Alg-silk bead based 3D platform is more efficient than
a 2D system. Thus we developed a platform which not only enables differentiation of stem cells in two distinct lineages in 3D, but it also provides an easy to fabricate, simple and
inexpensive in vitro model for expansion of hMSCs and to study fundamental aspects of stem cell differentiation in the 3D system. Development of such 3D scaffolds, which can direct differentiation on their own (due to material properties or other cues) without the need to provide exogenous factors is desirable. These scaffolds if implanted in vivo (in living organism), can control hMSCs differentiation much more effectively as functional groups are stable than growth factors,
peptides etc.
The beads were found to be superior to
2D culture and the cells behaved more natural than when cultured on a 2D with differentiating media. Since, alginate and silk fibroin are cheaper than many other biopolymers, the beads developed in this study offer an economical alternate 3D system supporting growth, fast and efficient differentiation of stem cells into osteocytes and chondrocytes and has a great translational potential.
Here, we formed 3D beads by crosslinking alginate with calcium ions and the silk fibroin trapped in the alginate bead slowly forms β sheets (silk fibres) due to the aqueous environment, resulting in a stable silk-alginate 3D bead.