Computer simulation-based nanothermal field and tissue damage analysis for cardiac tumor ablation

Radiofrequency ablation is a nominally invasive technique to eradicate cancerous or non-cancerous cells by heating. However, it is still hampered to acquire a successful cell destruction process due to inappropriate RF intensities that will not entirely obliterate tumorous tissues, causing in treatment failure. In this study, we are acquainted with a nanoassisted RF ablation procedure of cardiac tumor to provide better outcomes for long-term survival rate without any recurrences. A three-dimensional thermo-electric energy model is employed to investigate nanothermal field and ablation efficiency into the left atrium tumor. The cell death model is adopted to quantify the degree of tissue injury while injecting the Fe3O4 nanoparticles concentrations up to 20% into the target tissue. The results reveal that when nanothermal field extents as a function of tissue depth (10 mm) from the electrode tip, the increasing thermal rates were approximately 0.54362%, 3.17039%, and 7.27397% for the particle concentration levels of 7%, 10%, and 15% compared with no-particle case. In the 7% Fe3O4 nanoparticles, 100% fractional damage index is achieved after ablation time of 18 s whereas tissue annihilation approach proceeds longer to complete for no-particle case. The outcomes indicate that injecting nanoparticles may lessen ablation time in surgeries and prevent damage to adjacent healthy tissue.

Water-transport and Intracellular Ice Formation of Porcine Adipose-derived Stem Cells during Freezing

BACKGROUND

Water transport and intracellular ice formation are important processes that relate to cryoinjury of cells upon freezing. To date, no study is reported on the characteristics of water transport and intracellular ice formation in porcine adipose-derived stem cells (pADSC).

OBJECTIVE

To study water transport and intracellular ice formation upon freezing of pADSCs at different cooling rates.

MATERIALS AND METHODS

The pADSCs were isolated using collagenase digestion from a subcutaneous adipose tissue of a 28-day-old Landrace pig. Freeze experiments were performed in a gas tight chamber of cryomicroscopy stage at different cooling rates between 40°C and -150°C.

RESULTS

Water permeability coefficient L_pg and the activation energy E_LP decrease with increasing cooling rates for pADSCs. The probability of intracellular ice formation increases with increasing cooling rates, being 0.35, 0.4 and 0.5 for cooling rates at 20, 30 and 60 °C/min respectively.

CONCLUSION

Based on the characteristics of water transport and intracellular ice formation in pADSCs, slow freezing is perhaps more suitable for pADSC cryopreservation.