Colonisation inhibited

If a strip of cells is removed from a confluent monolayer of untransformed cells (e.g. 3T3 mouse embryo cells) then the cells at the edge of the wound are stimulated to synthesise DNA and divide. They quickly colonise the unoccupied area of the wound. This phenomenon known as topo inhibition (Dulbecco, 1970) is now explained by the presence in cells on the edge of the wound of an increased surface area exposed to the medium (i.e. neighbouring cells have been removed) (Stoker, 1973 Dulbecco and Elkington, 1973). 

Low levels of residual chlorine may be regarded as a biostat, i.e. preventing colonisation or restricting biofilm development. In a particular laboratory experiment [Kaur et al 1988] chlorine levels as low as 0.2 - 0.6 mg/l inhibited biofilm attachment and growth. The effect of flow velocity and chlorine concentration are shown on Fig. 14.14. 

A stable endothelization is a desirable characteristic for blood-contacting implants as a viable layer of endothelial cells would inhibit both bacterial colonisation and thrombus formation. 

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