Potential of microsensor-based feedback bioactuators for biophysical cancer treatment

Solid tumors usually exhibit a poorly organized vascularization and a deviant energy metabolism which result in an acidic pH and large hypoxic areas in the tumor microenvironment. A lot of cell biological data support the hypothesis that such physico-chemical conditions are promoters of the microevolution of malignant cells, inhibitors of the immune response, and co-factors for tumor cell invasion. Our experimental in vitro analyses and computer simulations indicate that the efficiency of immunotherapies and classical methods for cancer treatment might be improved if a physico-chemical microenvironment could be restored which reflects that found in normal tissue. In order to monitor and manipulate the tumor microenvironment, we suggest utilizing silicon-based feedback bioactuators which are controlled by on-line microsensors. These miniaturized bioactuators play the role of 'pH clamps' and can be implanted directly at the sites of inoperable tumors and metastases where they can reconstitute normal physico-chemical conditions. The drug application scheme can be precisely controlled by an integrated microprocessor. The paper summarizes the current state of development of such microsensor-based feedback bioactuators and outlines their potential for biophysical cancer treatment.