Current challenges in vascular medicine (e.g., bypass grafting, stenting, and angioplasty.) have driven the field of vascular regenerative medicine. Bone marrow-derived mesenchymal stem cells (BMMSCs) are adult stem cells which may be a suitable cell source for vascular regenerative medicine applications. While it is well known that BMMSCs readily differentiate into musculoskeletal cells, recent studies have provided evidence for their differentiation into smooth muscle cells (SMCs) and endothelial cells (ECs). We and others have demonstrated the ability of the mechanical stimulus of cyclic stretch to drive BMMSC differentiation towards SMCs in vitro, but a rigorous, systematic analysis of other relevant forces is lacking. The working hypothesis that this work addressed is that mechanical stimuli relevant to the vasculature will guide BMMSC differentiation towards SMCs and ECs.
To test this hypothesis, rat BMMSCs were exposed to physiologically relevant magnitudes and frequencies of a Mechanical Panel, which consisted of cyclic stretch, cyclic pressure, and shear stress, each applied in parallel to subcultures of BMMSCs. Quantitative changes in morphology, proliferation, and gene and protein expression were assessed to determine the differential effect of each stimulus in a dose- and frequency-dependant manner. Next, we investigated the importance of the duration of applied stimulation to BMMSC differentiation as well as tissue commitment (i.e., cell plasticity) following mechanical stimulation.
Our results demonstrate that mechanical stimulation differentially altered BMMSC morphology, proliferation, and gene and protein expression towards the cardiovascular lineage while limiting expression for other lineages including bone, fat, and chondrocyte. This was particularly evident for cyclic stretch, which caused an elongated, spindle-shape and expression of the SMC proteins alpha-actin, calponin, and myosin heavy chain. Furthermore, we found that cyclic pressure and shear stress tended to increase endothelial gene expression when these stimuli are applied to confluent BMMSCs. While our findings as a whole tended to support our hypothesis, our data indicate that SMC protein expression is more readily increased by mechanical stimulation, and is highly variable, even without associated changes in gene expression. Future work employing systems biology approaches that take into consideration the resulting transcriptional and proteomic changes in BMMSCs from these mechanical stimuli will be necessary to more accurately identify how mechanical stimulation can be used as a tool for regenerative medicine.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-10162007-171731 |
| Date | 30 January 2008 |
| Creators | Maul, Timothy Michael |
| Contributors | Johnny Huard, PhD, David A. Vorp, PhD, Satdarshan S. Monga, MD, William R. Wagner, PhD |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-10162007-171731/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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