Cryosurgery: ultrastructural changes in pancreas tissue after low temperature exposure

An In Vitro Investigation into Cryoablation and Adjunctive Cryoablation/Chemotherapy Combination Therapy for the Treatment of Pancreatic Cancer Using the PANC-1 Cell Line

As the incidence of pancreatic ductal adenocarcinoma (PDAC) continues to grow, so does the need for new strategies for treatment. One such area being evaluated is cryoablation. While promising, studies remain limited and questions surrounding basic dosing (minimal lethal temperature) coupled with technological issues associated with accessing PDAC tumors and tumor proximity to vasculature and bile ducts, among others, have limited the use of cryoablation. Additionally, as chemotherapy remains the first-line of attack for PDAC, there is limited information on the impact of combining freezing with chemotherapy. As such, this study investigated the in vitro response of a PDAC cell line to freezing, chemotherapy, and the combination of chemotherapy pre-treatment and freezing. PANC-1 cells and PANC-1 tumor models were exposed to cryoablation (freezing insult) and compared to non-frozen controls. Additionally, PANC-1 cells were exposed to varying sub-clinical doses of gemcitabine or oxaliplatin alone and in combination with freezing. The results show that freezing to −10 °C did not affect viability, whereas −15 °C and −20 °C resulted in a reduction in 1 day post-freeze viability to 85% and 20%, respectively, though both recovered to controls by day 7. A complete cell loss was found following a single freeze below −25 °C. The combination of 100 nM gemcitabine (1.1 mg/m2) pre-treatment and a single freeze at −15 °C resulted in near-complete cell death (<5% survival) over the 7-day assessment interval. The combination of 8.8 µM oxaliplatin (130 mg/m2) pre-treatment and a single −15 °C freeze resulted in a similar trend of increased PANC-1 cell death. In summary, these in vitro results suggest that freezing alone to temperatures in the range of −25 °C results in a high degree of PDAC destruction. Further, the data support a potential combinatorial chemo/cryo-therapeutic strategy for the treatment of PDAC. These results suggest that a reduction in chemotherapeutic dose may be possible when offered in combination with freezing for the treatment of PDAC.

Cryoimmunology: Opportunities and challenges in biomedical science and practice

Autologous and allogeneic cryoimmunological medicine is a brand new branch of biomedical science and clinical practice that examines the features and formation of the immune response to immunogenic properties of normal and malignant biological structures altered by ultralow temperature, as well as specific changes in the structural and functional characteristics of immune cells and tissues after cryopreservation. Cryogenic protein denaturation phenomenon provides important insights into the mechanisms underlying the damage to cryogenic lesions immediately after freeze-thawing sessions in bioscience and medicine applications. The newly formed cryocoagulated protein components (cryomodified protein components) are crucial in cryoimmunology from the perspective of the formation of immunological substances at ultralow temperatures. Dendritic cells and cryocell detritus (cryocell debris) formed in living biological tissue after exposure to ultralow temperature in vivo may be an indication of one of the essential mechanisms involved in the cryoimmunological response of living structures to the impact of ultralow temperature exposure. Hence, the formation of new autologous and allogeneic cryoinduced immunogenic substances is a novel concept in biomedical research globally. Accordingly, this review focuses on issues concerning the peculiarities of the interaction of the immune system with a dominant malignant neoplasm tissue after exposure to subzero temperatures, considering the original cryogenic technical approaches. We present an overview of the state-of-the-art methods of cryoimmunology, and their major developments, past and present. The need for the delineation of structural and functional characteristics of the biological substrates of the immune system after cryopreservation that can be used in adoptive cell therapy, especially in cancer patients, is emphasized.

Breast Cancer Cryoablation: Assessment of the Impact of Fundamental Procedural Variables in an In Vitro Human Breast Cancer Model

INTRODUCTION

Breast cancer is the most prominent form of cancer and the second leading cause of death in women behind lung cancer. The primary modes of treatment today include surgical excision (lumpectomy, mastectomy), radiation, chemoablation, anti-HER2/neu therapy, and/or hormone therapy. The severe side effects associated with these therapies suggest a minimally invasive therapy with fewer quality of life issues would be advantageous for treatment of this pervasive disease. Cryoablation has been used in the treatment of other cancers, including prostate, skin, and cervical, for decades and has been shown to be a successful minimally invasive therapeutic option. To this end, the use of cryotherapy for the treatment of breast cancer has increased over the last several years. Although successful, one of the challenges in cryoablation is management of cancer destruction in the periphery of the ice ball as the tissue within this outer margin may not experience ablative temperatures. In breast cancer, this is of concern due to the lobular nature of the tumors. As such, in this study, we investigated the level of cell death at various temperatures associated with the margin of a cryogenic lesion as well as the impact of repetitive freezing and thawing methods on overall efficacy.

METHODS

Human breast cancer cells, MCF-7, were exposed to temperatures of -5°C, -10°C, -15°C, -20°C, or -25°C for 5-minute freeze intervals in a single or repeat freeze-thaw cycle. Samples were thawed with either passive or active warming for 5 or 10 minutes. Samples were assessed at 1, 2, and 3 days post-freeze to assess cell survival and recovery. In addition, the modes of cell death associated with freezing were assessed over the initial 24-hour post-thaw recovery period.

RESULTS

Exposure of MCF-7 cells to -5°C and -10°C resulted in minimal cell death regardless of the freeze/thaw conditions. Freezing to a temperature of -25°C resulted in complete cell death 1 day post-thaw with no cell recovery in all freeze/thaw scenarios evaluated. Exposure to a single freeze event resulted in a gradual increase in cell death at -15°C and -20°C. Application of a repeat freeze-thaw cycle (dual 5-minute freeze) resulted in an increase in cell death with complete destruction at -20°C and near complete death at -15°C (day 1 survival: single -15°C freeze/thaw = 20%; repeated -15°C freeze/thaw = 4%). Analysis of thaw interval time (5 vs 10 minute) demonstrated that the shorter 5-minute thaw interval between freezes resulted in increased cell destruction. Furthermore, investigation of thaw rate (active vs passive thawing) demonstrated that active thawing resulted in increased cell survival thereby less effective ablation compared with passive thawing (eg, -15°C 5/10/5 procedure survival, passive thaw: 4% vs active thaw: 29%).

CONCLUSIONS

In summary, these in vitro findings suggest that freezing to temperatures of 25°C results in a high degree of breast cancer cell destruction. Furthermore, the data demonstrate that the application of a repeat freeze procedure with a passive 5-minute or 10-minute thaw interval between freeze cycles increases the minimal lethal temperature to the -15°C to -20°C range. The data also demonstrate that the use of an active thawing procedure between freezes reduces ablation efficacy at temperatures associated with the iceball periphery. These findings may be important to improving future clinical applications of cryoablation for the treatment of breast cancer.

Estimation of the stable frozen zone volume and the extent of contrast for a therapeutic substance

Background

In biomedical science and clinical practice, an estimation of the stable frozen zone volume and distribution of concentration fields of injected diagnostic and healing solutions in the tissues of living organisms is of great importance and does not currently have any mathematical solution aimed at its precise evaluation.

Objective

The aim of this research is the estimation of the stable frozen zone volume at ultra-low temperatures as well as the distribution of temperature areas and concentration fields of injected diagnostic and healing substances in vitro. The results can improve our understanding of the stable frozen zone volume and the extent of contrast for a therapeutic substance.

Materials and methods

A cryogenic zone (ice ball) was generated at -180°C using liquid nitrogen without any difficulties in vitro. The effects of freeze-thaw processes using ultra-low temperature and the cryogenic response of a 1.5% gelatin solution in water (%g/v) kept at a constant temperature of 20°C and continuously stirred were mathematically analyzed. The stable frozen zone volume was illustrated in vitro and measured in terms of its length, depth and cryogenic margin using a standard medical ruler and Vernier caliper after a freezing period at -180°C, using liquid nitrogen to provide cooling and freezing of a small portion of this solution in the vessel at room temperature (20°C). Round-shaped cryoprobes with diameters of 15 mm and 50 mm were applied to create a frozen zone volume in vitro. A single cryoprobe was used per procedure. The sample exposure time was 3 min. After this time, the volume of the frozen region remains unchanged, which indicates that the equilibrium stationary state has been reached. The experimental design, cryogenic procedure and freeze-thaw processes of the hemisphere were described and illustrated in vitro item by item. The statistical analysis manifested significant differences that were found between the 50 mm and 15 mm cryoprobes with regards to the freezing diameter, depth, and cryogenic margin (P < 0.001).

Results

An illustrated analytical mathematical solution of equations determined the stable frozen zone volume and the radius of the sphere of the frozen medium in the equilibrium stationary state. The resulting assessment provided the basis for the creation of mini- and micro-cryoprobes as well as cryoneedles for local tissue freezing in living biological structures. A solution to the equations was obtained under the boundary conditions with a set stable temperature value on the boundary surface of the cryoprobe as well as at the surface well-away from it, where the temperature is equal to the stable temperature of the environment. For example, this solution gives that in the case of a hemispherical cryoprobe radius of 1 mm, the frozen zone volume was more than three orders of magnitude greater than the volume of the cryoprobe itself and was equal to approximately 4 cm³. The determination of the fractal dimension can consider the individual characteristics of the spread of the contrast medium or therapeutic substance(s) in living tissue. Based on fractal theory, our innovative mathematical formulas allow for the assessment of the effective distribution of contrast medium in living biological structures, specifically for tissues assessed for diagnostic purposes, and they enable the selection of an optimal treatment strategy in medical practice.

Conclusion

A simple mathematical approach to solving the problems of assessing the stable frozen zone volume and distribution of temperature areas and concentration fields of injected diagnostic and healing substances in living biological structures, particularly living tissue in vitro, is presented in this study. The expressed quantitative mathematical formulas determine the stable stationary frozen zone volume and provide the basis for the creation of mini- and micro-cryoprobes. The application of fractal theory is proposed for assessing the distribution efficiency of contrast medium and therapeutic substance(s) in living biological structures for diagnostic purposes and for selecting a compassionate treatment strategy in medical professional practice.

Immune Status of Pancreatic Cancer Patients Receiving Cryosurgery

Cryosurgery used on patients with unresectable pancreatic cancer improved their quality of life, but mainly because of the pain relief. In postoperative patients, multifaceted changes in immunity were found, and the state of the immune system prior to surgery often was a decisive factor to indicate whether further disorders in the postoperative period would develop, or by contrast, it would boost its recovery. Some patients receiving cryosurgery showed immune system imbalance and activation, and of antitumor immunity in particular. It has been suggested that the advisability of immunotropic therapy for specific treatment algorithms should be predicted or the therapy should be suspended at some pathologic stage, and this has been immunologically confirmed. Cryosurgery should be considered as a reasonable alternative to the existing types of surgery for pancreatic cancer or as an essential component of multimodal therapy, consisting of topical cryosurgery, chemotherapy, and immunotropic therapy, to boost antitumor immunity and to discontinue cytoreductive therapy due to its toxic effects.

Thermal ablation of pancreatic cancer: A systematic literature review of clinical practice and pre-clinical studies

PURPOSE

Pancreatic cancer is a challenging malignancy with low treatment option and poor life expectancy. Thermal ablation techniques were proposed as alternative treatment options, especially in advanced stages and for unfit-for-surgery patients. This systematic review describes the thermal ablative techniques -i.e., Laser (LA), Radiofrequency (RFA), Microwave (MWA) Ablation, High-Intensity Focused Ultrasound (HIFU) and cryoablation- available for pancreatic cancer treatment. Additionally, an analysis of the efficacy, complication rate and overall survival for each technique is conducted.

MATERIAL AND METHODS

This review collects the ex vivo, preclinical and clinical studies presenting the use of thermal techniques in the pancreatic cancer treatment, searched up to March 2018 in PubMed and Medline. Abstracts, letters-to-the-editor, expert opinions, reviews and non-English language manuscripts were excluded.

RESULTS

Sixty-five papers were included. For the ex vivo and preclinical studies, there are: 12 records for LA, 8 for RFA, 0 for MWA, 6 for HIFU, 1 for cryoablation and 3 for hybrid techniques. For clinical studies, 1 paper for LA, 14 for RFA, 1 for MWA, 17 for HIFU, 1 for cryoablation and 1 for hybrid techniques.

CONCLUSIONS

Important technological advances are presented in ex vivo and preclinical studies, as the real-time thermometry, nanotechnology and hybrid techniques to enhance the thermal outcome. Conversely, a lack of standardization in the clinical employment of the procedures emerged, leading to contrasting results on the safety and feasibility of some analyzed techniques. Uniform conclusions on the safety and feasibility of these techniques for pancreatic cancer will require further structured investigation.

Clinical Practice Guidelines for Cryosurgery of Pancreatic Cancer: A Consensus Statement From the China Cooperative Group of Cryosurgery on Pancreatic Cancer, International Society of Cryosurgery, and Asian Society of Cryosurgery

Pancreatic cancer (PC), one of the most lethal malignancies, accounts for 8% to 10% of digestive system cancers, and the incidence is increasing. Surgery, chemotherapy, and radiotherapy have been the main treatment methods but are not very effective. Cryosurgery was first used in 1984 for treatment of locally advanced PC and has since become a considerable treatment for most cases of unresectable PC. During the past decade, cryosurgery has been applied in some hospitals in China, and the newly developed technique of computed tomography- and/or ultrasound-guided percutaneous cryosurgery has shown better results than chemotherapy in cases of unresectable locally advanced PC, with the 1-year survival rate reported to be more than 50%. To develop standardized criteria for the application of cryosurgery in PC, the International Society of Cryosurgery and Asian Society of Cryosurgery assembled experts from Austria, Japan, and China to discuss treatment methods and arrive at a consensus on the indications, contraindications, and preferred techniques of PC cryosurgery.

Cryosurgery for pancreatic cancer

The procedure of pancreatic cryosurgery is performed with intraoperative or percutaneous approaches. Based on current data and our initial experience, cryoablation appears to be a feasible, potentially safe and promising option in patients with locally advanced and unresectable pancreatic cancer. It is suggested that there are almost no known contraindications to the use of cryosurgery for pancreatic cancer. For most patients with pancreatic cancer, cryosurgery can substitute conventional surgery.

Factors affecting tumor ablation during high intensity focused ultrasound treatment

BACKGROUND/AIMS

High intensity focused ultrasound (HIFU) utilizes a targeted extracorporeal focused ultrasound beam to ablate neoplastic pancreatic tissue. We used an in vitro model to examine the effects of bone, metallic stents, plastic stents, metal plates, and cyst-like lesions on HIFU treatment.

METHODS

HIFU was delivered to the phantom models implanted with foreign bodies, and the location, shape, and size of the ablated zones were evaluated.

RESULTS

Bone and metallic plates reflected the ultrasound beam, shifting the ablation zone from the focal zone to the prefocal area. In the phantoms containing metal stent, plastic stent, and cyst, most of the ablative energy was reflected to the prefocal area by the surface, with the remainder penetrating through the phantom. The area of the ablated margins was significantly larger in size and volume than the intended focal ablation zone.

CONCLUSIONS

During HIFU therapy, artificial or anatomical barriers could affect the direction of the ultrasound beams, shifting the ablation zone from the focal area to a prefocal site with a larger than expected ablation zone. These factors should be considered prior to HIFU treatment for pancreatic tumors because they could limit ablation success, in addition to causing complications.

Two case reports of pilot percutaneous cryosurgery in familial multiple endocrine neoplasia type 1

We report 2 cases of familial multiple endocrine neoplasia type 1 syndrome (MEN 1) in related Malaysian Chinese individuals: the son had simultaneous primary lesions in the pancreatic tail, parathyroid, adrenal gland, and hypophysis, with metastatic tumors in the left lung, mediastinum and spine; his mother had simultaneous primary lesions in the pancreatic head, parathyroid, and hypophysis, with metastatic tumors in the liver, spine, ilium, chest wall, and rib. Genetic testing of the 2 patients showed the same mutation in exon 9 of MEN1 (c.1288G>T, Glu430, encoding a stop codon). The tumors with the poorest prognosis and clinical sequelae were in the pancreas of both patients, and these were treated by percutaneous cryoablation. The number of hypoglycemic episodes in the son improved for more than 120 days, and the abdominal space occupying lesion resolved in his mother.

Radical treatment of stage IV pancreatic cancer by the combination of cryosurgery and iodine-125 seed implantation

AIM: To investigate the therapeutic effect of radical treatment and palliative treatment in stage IV pancreatic cancer patients.

METHODS: 81 patients were enrolled in the study. Radical treatment was performed on 51 patients, while 30 patients were put under palliative treatment. The procedural safety and interval survival for stage IV pancreatic cancer (IS-IV) was assessed by almost 2.5 years of follow-ups. The IS-IV of patients under the two kinds of treatment, and the effects of treatment timing and frequency on IS-IV, were compared.

RESULTS: The IS-IV of patients who received radical treatment was significantly longer than those who received palliative treatment (P < 0.001). The IS-IV of patients who received delayed radical or palliative treatment was longer than those who received accordingly timely treatment (P = 0.0034 and 0.0415, respectively). Multiple treatments can play an important role in improving the IS-IV of patients who received radical treatment (P = 0.0389), but not for those who received palliative treatment (P = 0.99).

CONCLUSION: The effect of radical treatment was significantly more obvious than that of palliative treatment, and multiple radical treatments may contribute more to patients than a single radical treatment.

Pancreatic head cryosurgery: safety and efficiency in vivo--a pilot study

OBJECTIVES

Pancreatic cancer is the fourth leading cause of cancer-related death. Cryosurgery has emerged as a promising new technique for treatment. Although 80% of pancreatic cancers are located in the pancreatic head, no research has been conducted on the safety and efficacy of cryosurgery for these tumors.

METHODS

Two groups of Tibetan miniature pigs (n = 4 per group) underwent cryosurgery to the pancreatic head with either the deep freezing protocol (100% argon output) or shallow freezing protocol (10% argon output), and compared to sham-operated pigs.

RESULTS

Serum inflammatory factors and amylase increased during the 5 days after cryoablation in both groups but acute pancreatitis did not occur. Adhesions were observed between the pancreatic head and adjacent organs, and only minor trauma was caused to the stomach, duodenum, small intestine, and liver. Ice balls with a radius of 0.5 cm beyond the tumor edge were sufficient to cause complete necrosis of the pancreatic tissue, and decreased the degree of cold injury to surrounding tissues.

CONCLUSIONS

Shallow freezing protocol seemed to be safer than, and just as effective as, the deep freezing protocol. This preliminary study suggests that cryosurgery could potentially be an effective treatment of cancer of the pancreatic head.

Percutaneous ultrasonography and computed tomography guided pancreatic cryoablation: feasibility and safety assessment

OBJECTIVE

To assess the safety and feasibility of percutaneous cryoablation on pancreatic cancer via ultrasonography (US) and computed tomography (CT) guidance.

MATERIALS AND METHODS

This retrospective review was approved by the institutional review board and of informed consent. Thirty-two patients (18 men and 14 women; median age 62; age range, 30-77 years) with pancreatic cancer (stage II/III/IV, 3/11/18) treated with percutaneous US and CT guided cryoablations between February 2009 and February 2010 were eligible for this review. Thirteen tumors in pancreatic head and 19 in pancreatic body and/or tail measuring 2-11 cm (mean, 5.2 cm±8 [standard deviation]) were ablated with 49 procedures in total. Feasibility was analyzed by enhanced CT 1-3 months post procedure and safety was assessed by clinical signs, symptoms and laboratory results.

RESULTS

Neither procedural death nor serious complications occurred. Fifteen tumors (46.9%) smaller than 5 cm were successfully ablated by one session of cryoablation. Twenty-seven patients experienced a ≥50% reduction in pain score, 22 experienced a 50% decrease in analgesic consumption and 16 experienced a ≥20 increase in Karnofsky Performance Status (KPS) Score. Partial response (PR) and stable disease (SD) turned up in 9 and 21 patients, respectively, lesions in whom were identified controlled by none enhancement on enhanced CT. Mean and median survival was 15.9 and 12.6 months, respectively. The 6-, 12- and 24-month survival rates were 82.8%, 54.7% and 27.3%, respectively.

CONCLUSION

US and CT guided percutaneous cryoablation is a safe and promising local treatment for pancreatic cancer.

Experimental cryosurgery investigations in vivo

Cryosurgery is the use of freezing temperatures to elicit an ablative response in a targeted tissue. This review provides a global overview of experimentation in vivo which has been the basis of advancement of this widely applied therapeutic option. The cellular and tissue-related events that underlie the mechanisms of destruction, including direct cell injury (cryolysis), vascular stasis, apoptosis and necrosis, are described and are related to the optimal methods of technique of freezing to achieve efficacious therapy. In vivo experiments with major organs, including wound healing, the putative immunological response following thawing, and the use of cryoadjunctive strategies to enhance cancer cell sensitivity to freezing, are described.

Cryosurgery: early ultrastructural changes in liver tissue in vivo

BACKGROUND

Experimental observations with regard to freezing in vitro cell lines and fluid systems led to the application of low temperatures to in vivo biological systems. For the first time, this report describes the cryosurgical response of liver parenchyma and the early ultrastructural cellular changes in liver tissue, i.e., cryosurgery, in vivo.

MATERIALS AND METHODS

Forty-eight animals were used for the experiment. The dogs were divided into four groups. In group A, the liver tissue was frozen to -80 degrees C and in group B, to -180 degrees C. Temperatures of -80 degrees C and -180 degrees C in contact with liver tissue was selected for cryosurgical exposure. For transmission electron microscopy, the specimens were taken immediately and 1 h after the finishing of the freeze-thaw cycles intraoperatively. Further, the next specimens were taken in 24 h, this time also intraoperatively.

RESULTS

The electronic microscopic analysis showed that, after local cryodestruction at temperatures of -80 degrees C and -180 degrees C, similar processes occurred within the liver tissue in the early postcryosurgical phase-immediately and 1 h after cryosurgical session. The hepatocytes in the center of the cryozone changed upon thawing. Ultrastructural changes in the hepatic cells, where the first signs of dystrophic processes had been noticed, were increased.

CONCLUSIONS

Our new insights prove on the cell level that suddenly and progressively damaged liver cells in the postcryosurgical zone lead to aseptic cryoaponecrosis and then to aseptic cryoapoptosis of vital normal tissue. The vascular capillary changes and circulatory stagnation demonstrate together with cryoaponecrosis and cryoapoptosis the anti-angiogenesis mechanisms, which are some of the main mechanisms of biological tissue injury following the low temperature exposure.

A pilot study on combination of cryosurgery and 125iodine seed implantation for treatment of locally advanced pancreatic cancer

AIM: To study the therapeutic value of combination of cryosurgery and ¹²⁵iodine seed implantation for locally advanced pancreatic cancer.

METHODS: Forty-nine patients with locally advanced pancreatic cancer (males 36, females 13), with a median age of 59 years, were enrolled in the study. Twelve patients had liver metastases. In all cases the tumors were considered unresectable after a comprehensive evaluation. Patients were treated with cryosurgery, which was performed intraoperatively or percutaneously under guidance of ultrasound and/or computed tomography (CT), and ¹²⁵iodine seed implantation, which was performed during cryosurgery or post-cryosurgery under guidance of ultrasound and/or CT. A few patients received regional celiac artery chemotherapy.

RESULTS: Thirteen patients received intraoperative cryosurgery and 36 received percutaneous cryosurgery. Some patients underwent repeat cryosurgery. ¹²⁵Iodine seed implantation was performed during freezing procedure in 35 patients and 3-9 d after cryosurgery in 14 cases. Twenty patients, 10 of whom had hepatic metastases received regional chemotherapy. At 3 mo after therapy, CT was repeated to estimate tumor response to therapy. Most patients showed varying degrees of tumor necrosis. Complete response (CR) of tumor was seen in 20.4% patients, partial response (PR), in 38.8%, stable disease (SD), in 30.6%, and progressive disease (PD), in 10.2%. Adverse effects associated with cryosurgery included upper abdomen pain and increased serum amylase. Acute pancreatitis was seen in 6 patients one of whom developed severe pancreatitis. All adverse effects were controlled by medical management with no poor outcome. There was no therapy-related mortality. During a median follow-up of 18 mo (range of 5-40), the median survival was 16.2 mo, with 26 patients (53.1%) surviving for 12 mo or more. Overall, the 6-, 12-, 24- and 36-mo survival rates were 94.9%, 63.1%, 22.8% and 9.5%, respectively. Eight patients had survival of 24 mo or more. The patient with the longest survival (40 mo) is still living without evidence of tumor recurrence.

CONCLUSION: Cryosurgery, which is far less invasive than conventional pancreatic resection, and is associated with a low rate of adverse effects, should be the treatment of choice for patients with locally advanced pancreatic cancer. ¹²⁵Iodine seed implantation can destroy the residual surviving cancer cells after cryosurgery. Hence, a combination of both modalities has a complementary effect.