PhDCurrent golden standard therapy for bone repair and regeneration involves the use of
auto grafts. Nevertheless, there are many drawbacks associated with auto grafts
including donor site morbidity, requirement for an invasive surgery, post-operative
pain and infection. The use of injectable tissue engineered bone is an attractive
alternative, providing a minimally invasive approach to regenerate bone. It offers
faster healing, less pain and exact conformation to irregular defects. The present work
is designed to achieve injectable formulations of tissue engineered bone that fulfil the
requirements needed. It involves investigation of potential polymeric binders that are
biocompatible, biodegradable and allow bone formation when combined with cells.
Chitosan binders were tested for biocompatibility, biodegradability, gelation,
angiogenic potential and osteogenic differentiation and bone formation when mixed
with goat and human bone marrow derived mesenchymal stem cells (gMSCs,
hMSCs). An in vivo bone formation study was performed to investigate the bone
formation ability of gMSCs in contact with chitosan binder. Chick chorioallantoic
membrane assay was carried out to examine the angiogenic potential of the chitosan
binder combined with/without hMSCs. Furthermore, MC3T3-El cells were employed
to assess the osteogenic potential of cells exposed to chitosan polymeric systems.
Chitosan binder was proved to be an attractive polymer to carry cell-scaffold
combination. hMSCs were able to survive and differentiate along the osteogenic
lineage when encapsulated with 1.5% (w/v) chitosan-15% (w/v) glycerol phosphate
(GP)-0.18% (w/v) hydroxyethyl cellulose (HEC) in a 14-day study. Furthermore,
chitosan-GP-HEC solutions demonstrated fast gelation at 37°C. Chitosan was
biodegradable following 42 days in the presence/absence of lysozyme. Moreover,
gMSCs combined with chitosan binder produced 24.6 ± 13.7% bone comparable to
the control group after a 6-week implantation in mice. Chitosan was shown to be nonangiogenic
unlike hMSCs which showed angiogenic potential. Also, chitosan was
found to be osteogenic at 2 and 0.05 mg/ml concentrations