Book of abstract 2008

Kinetics of tumour growth and of vascular perfusion flow in
electrochemotherapy
Eberhard Neumann
Physical and Biophysical Chemistry, Faculty of Chemistry, University of Bielefeld, D-33501 Bielefeld,
POB 100131, Germany
It is shown that experimental tumour growth and tumour perfusion flows in electroporationbased
clinical treatments like electrochemotherapy (ECT) can be quantitatively analyzed
in terms of nonlinear flow relationships, using the concept of time-dependent flow
coefficients (reflecting time-dependences of flow cross sections, for instance of vascular
blood flow).
This novel, simple and powerful, approach of minimum complexity yields, for instance,
characteristic perfusion flow coefficients, stationary recovery levels indicating efficiency of
perfusion blocks by ECT, and characteristic time constants for the recovery of electrically
treated tumour cells and blood vessels under different pulse conditions (from staining the
tumours as a function of time (t/h) during the recovery phase after drug application and
electric pulses).
The characteristic parameters of the integrated tumour growth equations are in terms of
up to 20 days and more.
The new method for the quantitative analysis of the results of electroporation data
obtained with pulse trains rationalizes, for instance, that a pulse train of 8 pulses and a
repetition frequency 1 Hz (8 s total train time) is electroporatively more efficient than the
shorter pulse train of 5 kHz (1.6 ms total train time).
The reason for the efficiency of longer time intervals between the individual pulses of
a train is the well documented longevity of electroporation-induced structural changes,
leading to long-lived permeability increase of membranes for drugs, and finally also to
constrictively blocking tumour blood vessels.
44
l29