In situ gelling nanoparticulate systems for tissue engineering using stem cells

Edmund Carvalho
The aim of the current study was to ascertain whether three dimensional scaffold delivery systems could be developed along with nanoparticles to mediate differentiation in situ using the properties of the hydrogel scaffold and nanoparticles. The work was divided into three sections, 1. The development of in situ gelling scaffold systems, 2. Encapsulation and differentiation of ES cells within the scaffold systems, 3. Nanoparticulate approaches to facilitate ES cell differentiation towards the
more » ... ation towards the cardiac lineage. Gellan which can be crosslinked with calcium to form scaffolds while HPMC which was thermoresponsive were chosen to form scaffolds. Gellan and gellan HPMC blends were prepared to further employ the thermoresponsiveness of HPMC to improve the properties of the in situ gelling scaffolds prepared. It was found that the average gelation time of the gellan HPMC(GH) crosslinked with 3mM calcium blends 9:1 and 8:2 was 12 min and 16 min respectively and that for 0.5% gellan blended with 3mM calcium, was 26 min which was within the range of ASTM standards for in situ gelation. The volume of pores present in all of the blends were in the range of 80 to 90 % suggesting that the porous volume of the scaffolds was occupied completely with water once hydrated. The calcium crosslinked gels were porous and non-toxic indicating that the gels suitably network and ensure a viable environment. The 0.5GH8:2-3 blend showed promise and indicated that an increase in the concentration coupled with the addition of calcium improves the overall properties of the hydrogel so formed. Temperature dependent rheology suggested that 0.5GH 8:2-3 shared properties similar to 0.5G-3. The extended viability of the cells as well as tan d in vitro, makes 0.5%GH 8:2 with 3mM calcium more similar to 0.5% G-3. We finally considered gellan crosslinked with calcium for encapsulation of embryoid bodies. Scanning electron microscopy indicated EB presence within scaffold matrix. EB, beating efficiency on day 19 from 1.5 mM to 3 mM and 6 mM. showed that th [...]
doi:10.4225/03/58b3c2ec2d94b fatcat:l7qztgeyl5fnbefcoigal4pwzu