Increased Cell Detachment Ratio of Mesenchymal-Type Lung Cancer Cells on pH-Responsive Chitosan through the β3 Integrin

Hydrogels with dual sensitivity to temperature and pH in physiologically relevant ranges as supports for versatile controlled cell detachment

Thermosensitive hydrogels based on the N-vinyl caprolactam (VCL), capable of allowing for cell adhesion and proliferation, as well as non-aggressive detachment by controlled temperature drop, were functionalized with 23 % or lower molar percentages of the cationizable hydrophobic unit 2-(diisopropylamino) ethyl methacrylate (DPAEMA), to obtain networks with dual sensitivity to temperature and pH. The swelling analysis of the systems has shown a transition pK (pKb) close to physiological values, dependent on the temperature of the medium (pKb of 6.6 and 6.9 when the temperature of the medium is above and below the transition temperature VPTT, respectively) and little dependence on the degree of functionalization of DPAEMA. In addition, at temperatures below the transition temperature (VPTT), the systems have shown large swelling variations as a function of the pH (i.e. below and above the pKb), exhibiting greater absorption capacity at pHs below pKb, where the DPAEMA units are cationized. Cytocompatibility and transplant capacity have been evaluated using the C166-GFP endothelial cell line. None of the thermosensitive hydrogels with variable DPAEMA content showed a delay with respect to the control without DPAEMA neither in terms of adhesion nor in proliferation. However, by increasing the percentage of DPAEMA functionalization -and decreasing thermosensitivity-, a correlative decrease in mitochondrial activity was obtained in the transplant, with significant differences for the hydrogels with DPAEMA molar percentage of 3 % or higher. Taking advantage of the proximity of the pKb to the physiological value, we have evaluated the cellular response and the capacity for transplantation after lowering the pH to 6.5, below pKb. A direct relationship of the DPAEMA functionalization degree on the detachment efficiency was observed, since the hydrogels with the highest molar load of DPAEMA showed higher mitochondrial metabolic activity after cell detachment.

Cell detachment ratio on pH-responsive chitosan: A useful biometric for prognostic judgment and drug efficacy assessment in oncology

The inherently unpredictable complexity of tumors impedes the widespread practice of the molecular biomarkers in outcome prediction. Alternatively, from the biophysical perspective, this study sought to investigate the applicability of the cell detachment ratio (CDR) derived from pH-responsive chitosan as a biometrical identifier for the disease state in cancer prognostic judgment and drug efficacy assessment. In the targeted therapy model, the repression of tumor dissemination in cells harboring aberrant ErbB signals (human non-small cell lung cancer cell line PC9 and breast cancer cell line BT474) were first demonstrated both in vitro and in vivo. Consequently, the corresponding CDR profile goes synchronously with the extent of cancer regression in response to the medication. Definitive integrins that drive the cell detachment were also verified through CDR examination following the integrin functional blockade. Conclusively, CDR is a promising clinical index for evaluation of the metastatic cell behaviors in terms of the cell detachment.