Vascular diseases can be modeled in vitro using tissue engineered blood vessels (TEBVs) for clinical research and drug screening. Smooth muscle cells (SMCs) compose the majority of the blood vessel wall and mediate contraction and regulation of blood flow; thus, SMCs are typically used as the key cellular component in TEBVs. However, primary SMCs pose several challenges, including limited cell sourcing and passaging, and lot-to-lot variation in their ability to form TEBVs. This thesis explores the use of stem cell-derived human vascular SMCs as an alternative source of contractile human SMCs. The goal of the current study was to evaluate human mesenchymal stem cells (hMSCs) as a cell source for creating self-assembled human SMC rings as model vascular tissues. Unlike primary human SMCs, hMSCs are proliferative in culture and readily harvested from autologous adult tissues, such as bone marrow and adipose tissue. To stimulate hMSC differentiation into vascular SMCs, we adapted a previously reported approach that utilized transforming growth factor beta 1 (TGF-β1) and bone morphogenetic protein 4 (BMP4) to differentiate hMSCs to SMC in 2D, and applied it to our self-assembled cell ring method to differentiate hMSCs within 3D tissues. Treatment groups focused on the use of 1% FBS, which is known to drive smooth muscle differentiation, versus 5% FBS. As well as the effects of timing for growth factor delivery. Histological analysis showed successful ring formation characterized by aligned nuclei and even collagen distribution. An increase in contractile proteins SMA and SM22α expression was observed with the addition of growth factors indicating differentiation towards SMC. Function was assessed using wire myography showing contractility of the differentiated rings in response to the vasoactive agonist carbachol. Through using a combination of TGF-β1 and BMP-4 we successfully fabricated functional 3D SMC tissue rings that can be used to form TEBVs or individually for disease modeling or drug screening.
Marsha Rolle, PHD Associate Professor, Department of Biomedical Engineering, WPI (Thesis Advisor)
Glenn Gaudette, PHD Professor, Department of Biomedical Engineering, WPI (Chair)
Catherine Whittington, PHD Assistant Professor, Department of Biomedical Engineering, WPI