Falls among the elderly are a major source of injury, often leading to serious fractures, hospitalization, and death. Osteoporosis (OP) is a global problem intimately related with these fractures, characterized by reduced bone mass, increased bone fragility. There exists a high failure rate in the translation of treatments to osteoporotic populations. Mesenchymal stromal cell (MSC) transplantation as a therapeutic strategy for OP has not yet been examined in clinical trials. This may be attributed to the mixed findings of pre-clinical studies aimed at determining the efficacy of MSC therapy towards bone regeneration in OP.
The most common animal model of OP is ovariectomy (OVX) that simulates post-menopausal estrogen loss. A plethora of bone regeneration studies have used OVX models with 12-16 weeks post-OVX periods and have generally reported positive results from a variety of treatment modalities, including MSC therapy. However, the use of the minimum post-OVX period may not be appropriate to reflect the global changes in regenerative potential of OP patients. In our research group's previous study, MSC were isolated from a minimum 60 week post-OVX rat model, representing a severe case of OP. The MSC isolated from these animals are a unique cell population that we expect may better represent the outcomes of autologous cell therapies for the older patient population in the clinic.
In the present study, adipose and bone marrow derived MSC from OVX and age-matched animals were evaluated for their osteogenic and adipogenic differentiation potentials in culture through passage 10. Results from this study suggest that bone marrow derived-MSC maintain their phenotype and functionality more effectively than adipose derived-MSC in OP. Further investigations used regenerative medicine approaches for cell expansion on keratin protein coated microcarriers in static culture. Hair-derived keratin biomaterials have demonstrated their utility as carriers of biologics and drugs for tissue engineering. An optimal microcarrier was selected that demonstrated superior retention of the protein coating through electrostatic interactions and high cell viability.
Finally, the integration of cell-microcarriers into a perfusion bioreactor system was explored. Preliminary results demonstrated the feasibility of MSC growth and differentiation on microcarrier based packed beds. Moreover, AD-MSC from OP rats were unresponsive to both inductive media and shear stress related osteogenic cues. These results highlight the complexity and challenges associated with the MSC regenerative strategy. / Doctor of Philosophy / Osteoporosis is a skeletal disease that results in reduced bone mass, increased bone fragility and fracture risk. Osteoporotic patients who experience falls suffer serious fractures, hospitalization, and poor bone healing. Several different therapies have been developed for the treatment of osteoporosis, though many are unable to translate from the bench to the clinical population. A popular treatment being investigated is the application of mesenchymal stromal cells (MSC) for fracture repair and the reversal of osteoporotic bone losses. However, cells isolated from aged and osteoporotic patients have been shown to have deficient bone forming properties. Nevertheless, animal models of osteoporosis applying this treatment report amelioration of bone loss.
This work seeks to examine a more clinically relevant rat model of osteoporosis. Typical osteoporosis models use an ovariectomy procedure to simulate post-menopausal bone loss on relatively young animals and conduct short-term studies. These studies may not accurately reflect the global regenerative changes in osteoporosis patients or the impaired MSC properties.
Adipose and bone marrow derived MSC from a long term ovariectomy model were investigated for their regenerative potentials. MSC growth and bone forming potential was evaluated on keratin protein coated microcarriers in both static and perfusion cultures. Results from this study suggest that bone marrow derived MSC maintain their phenotype and functionality more effectively than adipose derived MSC in osteoporosis. Further preliminary results demonstrated the feasibility of MSC growth and differentiation on microcarrier based packed beds. These results highlight the complexity and challenges associated with the MSC regenerative strategy.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/97582 |
| Date | 09 April 2020 |
| Creators | Saverot, Scott-Eugene |
| Contributors | Department of Biomedical Engineering and Mechanics, Van Dyke, Mark, Wang, Vincent M., Dahlgren, Linda A., Vlaisavljevich, Eli, Huckle, William R. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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