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Title: Molecular reponses of cell adhesion upon cell-cell contact initiation in a 2-D ultrasound standing wave trap
Author: Bazou, Despina
ISNI:       0000 0004 2749 4311
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2006
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This thesis explores the interactions of cells and particles brought into contact in suspension in an ultrasound standing wave trap as aggregates or monolayers. The influence of CaCb , and hence modulation of electrostatic particle interaction force, on the growth and morphology of aggregates of 25 urn latex spheres was initially characterised by techniques including fractal dimension, and void analysis. At low CaCb additions highly hexagonally ordered structures were formed while with increasing CaCb additions the aggregate morphology gradually 'crossed over' from being essentially closely packed to a dendritic, highly disordered one. The physical environment of cells aggregating in the trap was then examined to assess the extent to which ultrasound might influence cell viability and function. The temperature rise was < 0.5 K. The drag due to acoustic streaming was smaller than the stress imposed by gentle preparative cell centrifugation. The attractive acoustic force between cells was small compared to the force required to reverse a single receptor- receptor bond and to the attractive van der Waals force. Acoustic spectrum analysis detected no cavitation activity in the suspensions. Fluorescent indicators showed that the number of viable cells (99 %) did not change during 1 h in the trap. The progression of cell-cell interactions i.e. length of membrane-membrane contact, and the integral intensities of stained cadherin/catenin complex molecules, the actin cytoskeleton and (for chondrocytes) gap junctions were examined over 60 min in primary chondrocytes, and in neural, prostate epithelial and prostate cancer cell lines. The aggregate form changed concurrently from hexagonally ordered cells to a continuous sheet of mostly quadrilateral and pentagonal cells. Rapid molecular responses to cell contact in other systems are reviewed. The cells in this work progressed from physical aggregation, through molecular adhesion, to displaying the intracellular consequences of receptor interactions. The ability to form mechanically strong confluent cell monolayers that can be monitored in situ or harvested from the trap provides a technique with general potential for monitoring the synchronous development of cell responses to receptor-triggered adhesion.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available