Experimental Study On Nano-cryosurgery Of Liver Tumors And Development Of Cryosurgery System

Cancer is a leading health care problem of world.According to the statistic,liver cancer is the most commonly diagnosed cancer in the males younger than 65 years-of-age.Currently,chemotherapy,radiotherapy,surgical resection and combinations of these approaches are standard therapies of cancer treatments.However,each method has limitations,and none of them completely cures cancer.Cryosurgery is a minimally invasive treatment that utilize low temperatures to destroy abnormal tissues.The clinical monitoring methods for cryosurgery are almost based on the visualization of the ice ball.However,for a typical cryosurgery process,the effective killing region is always smaller than the ice ball.As a result,the end of the cryosurgery process can only be judged by the surgeons according to their experience.The subjective judgement is one of the main reasons for poor estimation of tumor ablation,which sparks high probability of recurrence and metastasis associate with cryosurgery.Being different from the previous optimization studies,we develop a novel approach with the aid of nanoparticles to enlarge the active killing region of entire ice ball,and thus it significantly decrease the difficulty of precise judgement of the cryosurgery only by applying the conventional clinical imaging techniques.To validate this approach,both the experiments on a tissue-scale phantom with embedded living HepG2 cells in agarose and on a cell-scale cryo-microscopic freeze-thaw stage are performed.The results indicate that the introduction of the self-synthesized Fe3O4 nanoparticles significantly improved cell killing in the cryosurgery and the range of killing is extended to the entire ice ball.The potential mechanism is further revealed by the cryo-microscopic study,which confirms the presence of Fe3O4 nanoparticles can significantly enhance the probability of intracellular ice formation and the cell dehydration during freezing.Moreover,this study also proposes an MRI-compatible phase change cryogenic surgical device that can achieve precise treatment under MRI guidance.Combined with nano-cryosurgery,it can reduce the damage to healthy tissues while ensuring the destructive effect on cancer tissue.Trail experiments revealed that the system could be used under MRI without artifacts of interference judgment.Simultaneously,the cryosurgery experiments of the tumor phantom and the isolated pig liver indicate that the system can operate normally and provide stable and efficient chilling performance.The study intends a solution for some of the problems of cryosurgery at the present stage from the surgical treatment design and surgical equipment.It is helpful for the combination of nano-cryosurgery and MRI imaging to construct an integrated system for diagnosis and treatment and solve the problems confronted by traditional cryosurgery.These findings may further promote the widespread clinical application of modern cryosurgery...