Tissue engineering therapies for cleft palate reconstruction

• Author / Creator

  Mostafa, Nesrine AZ

• This thesis was intended to develop two tissue engineering approaches for cleft palate reconstruction. One approach focused on developing a cell-based therapy in vitro, using osteogenically induced mesenchymal stem cells (MSCs). The other approach focused on the delivery of bone morphogenetic protein-2 (BMP-2) in a scaffold designed to provide sustained release after in vivo implantation.
  To develop a cell-based therapy, MSCs were cultured with combinations of dexamethasone, vitamin-D3, basic fibroblast growth factor (b-FGF), and BMP-2. A comparison between osteogenesis and adipogenesis was pursued to investigate the best combination. An optimal condition was obtained at dexamethasone (10 nM) and BMP-2 (500 ng/mL) for mineralization without increasing adipogenesis-related markers. BMP-2 and dexamethasone were found to be essential for mineralization of MSCs. The b-FGF mitigated osteogenesis and enhanced adipogenesis. Vitamin-D3 appeared essential for calcification only in the presence of b-FGF.
  Rodent models of both surgically induced and spontaneous cleft palate are available, but are subject to several limitations. Hence, we modified the dimension of the two published rodent models of cleft palate (mid palate cleft “MPC”, and alveolar cleft “AC”) and assessed bone healing by micro-computed tomography (μCT) and histology. Virtual planning was performed to determine the accurate design of MPC and AC defects based on preoperative μCT images. Planned dimensions were similar to dimensions reproduced surgically. There was no significant difference in percent bone filling between MPC group and AC group at weeks 4 and 8. The presented modifications for AC and MPC cleft models made them more reliable and clinically relevant. However, the MPC defect had less anatomical challenges and larger residual defect volume as compared to AC defect, therefore this model was used for subsequent studies.
  A nanofiber (NF) based scaffold with collagen (ACS) backbone impregnated with BMP-2 was prepared and implanted in the MPC defect. Five treatments were evaluated: no scaffold, ACS alone, ACS+BMP-2, NF+ACS, and NF+ACS+BMP-2. Constructs containing BMP-2 demonstrated enhanced bone healing as compared to other groups. Based on histologic evaluations, both H&E and trichrome staining, together with cross-sectional and 3D reconstructed μCT images, NF+ACS+BMP-2 treatment resulted in better and more consistent bone healing when compared to ACS+BMP-2 group.
  In conclusion, osteogenically induced MSCs and BMP-2 loaded in a NF based scaffold are promising bone tissue engineering therapies for cleft palate reconstruction.

• Subjects / Keywords

  • Tissue-engineering
  • Bone grafting
  • Cleft palate

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3QZ22R5W

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.