Investigating the behavior of vascular related cells in native and synthetic polymers using a micro reciprocating shear stress generated by a frequency controlled micropositionig stage
| Autor: | Ching-Wen Li, 李靜雯 |
|---|---|
| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 The purpose of tissue engineering is development a functional engineered tissue or organ to reconstruct lesion in vivo. Due to lack of a vascular network to support metabolism, tissue engineering usually suffers the problems of less oxygen diffusion and nutrient exchange after implantation. Hence, vascular tissue engineering is used to construct an engineered vascular network to solve these problems. However, it has been demonstrated that artificial blood vessels can well repair injured large diameter blood vessels (> 6 mm), but not small diameter (< 6mm) blood vessels. The phenomenon can be attributed to less endothelial cells retention and mechanical compliance on vascular graft. The goal of this thesis is to use a piezoelectric micro-positioning lead zirconate titanate (μPZT) stage to provide precise micro-reciprocating shear stress (MRSS) motions in horizontal for investigating the behaviors of vascular related cells on synthesis (tissue culture polystyrene (TCPS), polylactide (PLA), poly(lactic-co-glycolic acid (PLGA), plasma treated polydimethylsiloxane (PDMS)), and native polymers (gelatin and chitosan). Accordingly, a normalized shear stress distribution to enhance vascular related cells retention on vascular graft but is relatively material-irrelevant can be estimated. Bovine endothelial cell line (BEC) was used to demonstrate that the cell proliferation can be enhanced by micro-reciprocating shear stress of a particular normalized shear stress distribution (shear stress per cell). Through the culture of BECs on synthetic polymers (TCPS, PLGA, PDMS and PLA), we found that the normalized shear stress distribution for cell proliferation enhancement is 18 - 22 dyne/cm2. Accordingly, the reciprocating frequency for BEC proliferation enhancement on native polymers (gelatin and chitosan) was estimated. Further experiments demonstrated that the estimated reciprocating frequency indeed can enhance the BEC proliferation regardless of the scaffold materials. The micro-reciprocating shear stress approach was further employed to the culture of primary human vein endothelial cells (HUVECs) and human vascular smooth muscle cells (HASMCs) to estimate the maximum normalized shear stress distribution in TCPS, PLGA and gelatin for cell retention enhancement. Static culture results indicate that material property affects cell adhesive behavior, and HUVECs are more sensitive than HASMCs. The cells morphology turned to round shape and loop alignment was observed in a high shear stress condition. The round shape formation can be attributed to the horizontally reciprocating displacement of the MRSS motion. From the adhesion area difference of HUVEC cultured on synthetic and native polymer under shear stress stimuli, we observed that material characteristics and shear stress play an equally important role in HUVEC proliferation promotion, and HASMC is more sensitive to the shear stress. We found that HUVECs can grow on all materials and the proliferation can be apparently promoted under shear stress distribution between 250 dyne/cm2 and 460 dyne/cm2. The shear stress ranging from 80 dyne/cm2 to 100 dyne/cm2 can promote HASMC’s growth. The results indicate that materials with differential surface properties possess a consistent normalized shear stress distribution for cell proliferation enhancement. Therefore, we suggested that the coculture of HUVEC and HUASMC on vascular graft in vitro should be alternately provided with different shear stresses to promote retention of both vascular endothelial cells and vascular smooth muscle cells on vascular graft. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|