Cryosurgery: A review

Cryogenic Media in Biomedical Applications: Current Advances, Challenges, and Future Perspectives

This paper explores the crucial role of cryogenic mediums in driving breakthroughs within the biomedical sector. The objective was to investigate, critically discuss, and present the current knowledge and state-of-the-art practices, along with the challenges and perspectives of the most common applications. Through an extensive literature review, this work aims to supplement existing research, offering a comprehensive and up-to-date understanding of the subject. Biomedical research involving cryogenic mediums is advancing on multiple fronts, including the development of advanced medical technologies, clinical treatments for life-threatening conditions, high-quality biospecimen preservation, and antimicrobial interventions in industrial food processing. These advances open new horizons and present cutting-edge opportunities for research and the medical community. While the current body of evidence showcases the impressive impact of cryogenic mediums, such as nitrogen, helium, argon, and oxygen, on revolutionary developments, reaching definitive conclusions on their efficiency and safety remains challenging due to process complexity and research scarcity with a moderate certainty of evidence. Knowledge gaps further underline the need for additional studies to facilitate cryogenic research in developing innovative technological processes in biomedicine. These advancements have the potential to reshape the modern world and significantly enhance the quality of life for people worldwide.

Intravital tumor decellularization as a new approach to cancer treatment

This study demonstrates the possibility of tumor decellularization in living animals. Subcutaneous Ehrlich tumor induced by isolated Ehrlich ascitic carcinoma cells in mice was used as a model. The study also presents methods for ex vivo decellularization of human gastric adenocarcinoma (HGA) and hepatocellular carcinoma (HCC) induced by diethylnitrosamine (DEN) in rat. Sodium dodecyl sulfate (SDS) and Triton X-100 were used as detergents for tumor decellularization. The detergents for HGA and HCC were administered through organ vessels. For intravital decellularization of Ehrlich's subcutaneous tumor, detergents were injected directly into the tumor parenchyma. The results of the study showed that the effectiveness of tumor decellularization using SDS and Triton X-100 depended on the size, structure, stiffness and density of the tumor, as well as on the concentration, route and speed of detergent administration. The study also showed that an hour after the initiation of decellularization, the central part of Ehrlich's tumor changed the color, and after three hours, it completely acquired a translucent white color. Chemical contamination of tissues surrounding the tumor with the detergents was not observed. Histological studies showed the complete absence of all cellular components of Ehrlich's tumor and a slightly deformed extracellular matrix (ECM). There were no loco-regional recurrences or metastases of Ehrlich's tumor within 150 days after decellularization. The developed intravital decellularization method allows the effective removal of the cellular components and the DNA content of Ehrlich's subcutaneous tumor without compromising animal health. Additionally, this method can destroy tumor ECM, which will significantly improve the delivery of anticancer drugs to the tumor cells. However, more detailed and extensive studies are needed to develop an in vivo technique for isolated decellularization of the tumor or a part of the organ with the tumor. It is also necessary to identify less toxic decellularization agents and to develop the most efficient route for their delivery to the tumor cells.

The Evolving Role of Cryosurgery in Breast Cancer Management: A Comprehensive Review

Breast cancer is the most commonly diagnosed type of cancer, accounting for approximately one in eight cancer diagnoses worldwide. In 2020, there were approximately 2.3 million new cases of breast cancer globally, resulting in around 685,000 deaths. Consequently, there is an ongoing need to develop innovative therapeutic approaches that can improve both clinical outcomes and patient quality of life. The use of ultra-low cryogenic temperatures, facilitated by cryogenic media such as liquid nitrogen, has revolutionized the biomedical field and opened up new possibilities for advanced clinical treatments, including cryosurgery. Cryosurgery has demonstrated its feasibility as a minimally invasive technique for destroying breast tumors and eliciting a significant antitumor immune response in the host. This feature sets cryosurgery apart from other ablative techniques. It has been shown to be well tolerated and effective, offering several advantages such as simplicity, the avoidance of general anesthesia, minimal pain, low morbidity, short recovery time, cost-effectiveness, and notably, improved aesthetic outcomes. The reviewed studies indicate that cryosurgery holds promise in the management of early-stage breast cancer and metastatic disease, especially in triple-negative and Her2-positive molecular subtypes in conjunction with checkpoint inhibitors and anti-Her2 antibodies, respectively. Furthermore, the effectiveness of cryosurgery in the management of ductal carcinoma in situ should be investigated as an alternative modality to surgery or surveillance. The minimally invasive nature of cryosurgery has the potential to significantly enhance the quality of life for patients.

Endobronchial mucormycosis diagnosed by fiberoptic bronchoscopy

Introduction

Endobronchial mucormycosis is very rare with only few cases reported in the literature. Here, we report a rare presentation of pulmonary mucormycosis in a diabetic patient who presented with left lung collapse. Bronchoscopy revealed an endobronchial growth, mimicking a tumor, causing complete occlusion of the left main bronchus. Histopathology confirmed the diagnosis of invasive mucormycosis.

Case presentation

Male patient 35 years old with accidental discovered Diabetes Mellitus, complained of hoarseness of voice and dry irritating cough that didn't respond to antitussives and nonspecific treatment. CT chest was done and revealed left total lung collapse. Fiberoptic bronchoscopy was done and revealed total occlusion of the left main bronchus with whitish fungating glistening tissue from which biopsies were obtained. Histopathological examination was consistent with mucormycosis. A trial of medical treatment failed after which the patient was referred for surgical resection.

Conclusion

Successful treatment of mucormycosis requires early diagnosis; prompt administration of antifungal therapy, and surgical intervention when applicable. Aggressive surgical intervention to remove necrotic tissue is generally accepted as the therapeutic mainstay for endobronchial obstructing mucormycosis.

Cryoablation and Immunotherapy: An Enthralling Synergy for Cancer Treatment

As less invasive options for surgical tumor removal, minimally invasive ablative techniques have gained popularity. Several solid tumors are being treated with cryoablation, a non-heat-based ablation technique. Cryoablation data in comparison over time demonstrates better tumor response and faster recovery. Combining cryosurgery with other cancer therapies has been explored to improve the cancer-killing process. Cryoablation with the combination of immunotherapy, results in a robust and efficient attack on the cancer cells. This article focuses on investigating the ability of cryosurgery to create a strong antitumor response when combined with immunologic agents resulting in a synergetic effect. To achieve this objective, we combined cryosurgery with immunotherapy using Nivolumab and lpilimumab. Five clinical cases of lymph node, lung cancer, bone, and lung metastasis were followed and analyzed. In this series of patients, percutaneous cryoablation and addressing immunity agents were technically feasible. In the follow-ups, there appeared to be no radiological evidence of new tumor development.

In-situ cryo-immune engineering of tumor microenvironment with cold-responsive nanotechnology for cancer immunotherapy

Cancer immunotherapy that deploys the host's immune system to recognize and attack tumors, is a promising strategy for cancer treatment. However, its efficacy is greatly restricted by the immunosuppressive (i.e., immunologically cold) tumor microenvironment (TME). Here, we report an in-situ cryo-immune engineering (ICIE) strategy for turning the TME from immunologically "cold" into "hot". In particular, after the ICIE treatment, the ratio of the CD8+ cytotoxic T cells to the immunosuppressive regulatory T cells is increased by more than 100 times in not only the primary tumors with cryosurgery but also distant tumors without freezing. This is achieved by combining cryosurgery that causes "frostbite" of tumor with cold-responsive nanoparticles that not only target tumor but also rapidly release both anticancer drug and PD-L1 silencing siRNA specifically into the cytosol upon cryosurgery. This ICIE treatment leads to potent immunogenic cell death, which promotes maturation of dendritic cells and activation of CD8+ cytotoxic T cells as well as memory T cells to kill not only primary but also distant/metastatic breast tumors in female mice (i.e., the abscopal effect). Collectively, ICIE may enable an efficient and durable way to leverage the immune system for combating cancer and its metastasis.

The effective distance and cooling rate of liquid nitrogen-based adjunctive cryotherapy for bone tumors ex vivo

BACKGROUND

Liquid nitrogen (LN) has been used as an adjuvant cryotherapy for bone tumors including giant-cell tumor of the bone (GCTB) to remove residual tumor cells after curettage. This study evaluated variables related to the efficacy of LN-based cryoablation in the context of adjuvant treatment of GCTB using porcine femur bone model.

METHODS

A porcine femur bone model was adopted to simulate intralesional cryotherapy. A LN-holding cavity (point 1, nadir) in the medial epicondyle, 4 holes (points 2-5) in the shaft situated 5, 10, 15, and 20 mm away from the proximal edge of the cavity, and 2 more holes (points 6 and 7) in the condyle cartilage (10 and 20 mm away from the distal edge of the cavity) were made. The cooling rate was compared between the 5 points. The cellular morphological changes and DNA damage in the GCTB tissue attributable to LN-based cryotherapy were determined by H&E stain and TUNEL assay. Cartilage tissue at points 6 and 7 was examined for the extent of tissue injury after cryotherapy.

RESULTS

The temperature kinetics at points 1, 2 reached the reference target and were found to be significantly better than the reference (both p < 0.05). The target temperature kinetics were not achieved at points 4 and 5, which showed a significantly lower cooling rate than the reference (both p < 0.001) without reaching the -60°C target. Compared with untreated samples, significantly higher proportion of shrunken or apoptotic cells were found at points 1-3; very small proportion were observed at points 4, 5. Significantly increased chondrocyte degeneration was observed at point 6, and was absent at point 7.

CONCLUSION

The cryotherapy effective range was within 5 mm from nadir. Complications were restricted to within this distance. The cooling rate was unchanged after three repeated cycles of cryotherapy.

Application of local anaesthesia and cryosurgery for eyelid masses in dogs

Background

Eyelid mass removal and cryotherapy application using only local anaesthesia and restraint may benefit patients with high anaesthesia risks.

Objective

To evaluate and validate cryosurgery application using the CryoPen XL^® on palpebral masses under local anaesthesia for patients not suitable for general anaesthesia.

Methods

Thirty patients underwent the procedure between November 2015 and April 2020. The procedure steps were as follows: skin preparation and local anaesthesia of the affected eyelid; debulking by resection and/or squeezing out the inspissated material; cryosurgery and post‐operative care using topical medication, antibiotics and anti‐inflammatory ointment. The medical records of the patients who underwent the operation were evaluated. Moreover, a telephonic survey with the pet owners was performed to determine recurrence, time to recurrence, survivability and side effects.

Results

Among the 30 owners, 29 responded to the survey. Ten (10/38, 26.3%) masses recurred with an average time to recurrence of 6.0 months. The estimated average depths for all, non‐recurred, and recurred masses were 1.89, 1.88 and 1.90 mm, respectively. The average recurrence rate and time to recurrence were higher and earlier, respectively, than previously reported values. However, no patient presented intra‐ or post‐operative complications.

Conclusion

These findings suggest that local anaesthesia and cryosurgery using the CryoPen XL^® can be used in patients with eyelid masses who are not suitable for general anaesthesia. Compared with the surgical eyelid mass removal and blepharoplasty procedure, the reported procedure is time‐ and cost‐effective, with the additional benefit of not requiring general anaesthesia.

Evaluation of a numerical simulation for cryoablation - comparison with bench data, clinical kidney and lung cases

PURPOSE

The accuracy of a numerical simulation of cryoablation ice balls was evaluated in gel phantom data as well as clinical kidney and lung cases.

MATERIALS AND METHODS

To evaluate the accuracy, 64 experimental single-needle cryoablations and 12 multi-needle cryoablations in gel phantoms were re-simulated with the corresponding freeze-thaw-freeze cycles. The simulated temperatures were compared over time with the measurements of thermocouples. For single needles, temperature values were compared at each thermocouple location. For multiple needles, Euclidean distances between simulated and measured isotherms (10 °C, 0 °C, -20 °C, -40 °C) were computed. Furthermore, surface and volume of simulated 0 °C isotherms were compared to cryoablation-induced ice balls in 14 kidney and 13 lung patients. For this purpose, needle positions and relevant anatomical structures defining material parameters (kidney/lung, tumor) were reconstructed from pre-ablation CT images and fused with postablation CT images (from which ice balls were extracted by manual delineation).

RESULTS

The single-needle gel phantom cases showed less than 5 °C prediction error on average. Over all multiple needle experiments in gel, the mean and maximum isotherm distance were less than 2.3 mm and 4.1 mm, respectively. Average Dice coefficients of 0.82/0.63 (kidney/lung) and mean surface distances of 2.59/3.12 mm quantify the prediction performance of the numerical simulation. However, maximum surface distances of 10.57/10.8 mm indicate that locally larger errors have to be expected.

CONCLUSION

A very good agreement of the numerical simulations for gel experiments was measured and a satisfactory agreement of the numerical simulations with measured ice balls in patient data was shown.

Management of Early-Stage Esophageal Adenocarcinoma by Endoscopic Spray Cryotherapy in the Setting of Portal Hypertension With Varices

The use of endoscopic spray cryotherapy to manage pathological conditions of the esophagus has become increasingly common. This mucosal ablation technique is believed to carry a lower risk of bleeding than other modalities. A 71-year-old woman and a 64-year-old man with portal hypertension and varices were diagnosed with invasive esophageal adenocarcinoma during routine variceal surveillance. Staging by endoscopic ultrasound and computed tomography was uT1N0M0 in both patients. They each underwent mucosal ablation using liquid nitrogen cryosprays with no adverse events. Both cancers completely resolved with 2 treatments, and neither patient has shown recurrence of neoplasia during follow-up observations for up to 2 years.

Synthesis of Anthracene Conjugates of Truncated Antifreeze Protein Sequences: Effect of the End Group and Photocontrolled Dimerization on Ice Recrystallization Inhibition Activity

Biomacromolecular antifreezes distinguish ice from water, function by binding to specific planes of ice, and could have many applications from cryobiology to aerospace where ice is a problem. In biology, antifreeze protein (AFP) activity is regulated by protein expression levels via temperature and light-regulated expression systems, but in the laboratory (or applications), the antifreeze activity is "always on" without any spatial or temporal control, and hence methods to enable this switching represent an exciting synthetic challenge. Introduction of an abiotic functionality into short peptides (e.g., from solid-phase synthesis) to enable switching is also desirable rather than on full-length recombinant proteins. Here, truncated peptide sequences based on the consensus repeat sequence from type-I AFPs (TAANAAAAAAA) were conjugated to an anthracene unit to explore their photocontrolled dimerization. Optimization of the synthesis to ensure solubility of the hydrophobic peptide included the addition of a dilysine solubilizing linker. It was shown that UV-light exposure triggered reversible dimerization of the AFP sequence, leading to an increase in molecular weight. Assessment of the ice recrystallization inhibition activity of the peptides before and after dimerization revealed only small effects on activity. However, it is reported here for the first time that addition of the anthracene unit to a 22-amino-acid truncated peptide significantly enhanced ice recrystallization inhibition compared to the free peptide, suggesting an accessible synthetic route to allow AFP activity using shorter, synthetically accessible peptides with a photoreactive functionality.

Cryotherapy to treat benign skin tumours in conscious dogs

BACKGROUND

Cryotherapy can be used to treat benign skin lesions without general anaesthesia. This technique has only been described in anaesthetized dogs.

OBJECTIVE

To describe the feasibility, safety and efficacy of cryotherapy to treat benign skin tumours in conscious dogs.

ANIMALS

Twenty-five client-owned dogs with 52 skin tumours diagnosed as benign sebaceous neoplasia (46) or follicular cysts (six).

METHODS AND MATERIALS

Cryotherapy was performed in conscious dogs using a liquid nitrogen spray technique with a handheld spray-release system. If needed, cryotherapy was repeated every three to four weeks until complete cure was achieved or for a maximum of eight treatments. Effectiveness and adverse effects were recorded.

RESULTS

Resolution was obtained for 29 of 52 lesions (57%) with a median number of one to two cryotherapy sessions. Eighteen of 52 (35%) lesions shrank to <0.1 cm. In one case, the tumour enlarged after cryotherapy, and histopathological examination of the excisional biopsy revealed an apocrine gland carcinoma. Pain and discomfort during the treatment were the most common adverse effects (33%).

CONCLUSIONS AND CLINICAL IMPORTANCE

In the present study, cryotherapy was possible in conscious dogs and proved to be effective to cure or reduce the size of benign sebaceous tumours and follicular cysts. The procedure is safe but the degree of pain during the treatment needs to be further investigated. Worsening of the lesion after cryotherapy suggests the need for surgical removal and histopathological examination.

Ice-binding proteins and the applicability and limitations of the kinetic pinning model

Ice-binding proteins (IBPs) are unique molecules that bind to and are active on the interface between two phases of water: ice and liquid water. This property allows them to affect ice growth in multiple ways: shaping ice crystals, suppressing the freezing point, inhibiting recrystallization and promoting nucleation. Advances in the protein's production technologies make these proteins promising agents for medical applications among others. Here, we focus on a special class of IBPs that suppress freezing by causing thermal hysteresis (TH): antifreeze proteins (AFPs). The kinetic pinning model describes the dynamics of a growing ice face with proteins binding to it, which eventually slow it down to a halt. We use the kinetic pinning model, with some adjustments made, to study the TH dependence on the solution's concentration of AFPs by fitting the model to published experimental data. We find this model describes the activity of (moderate) type III AFPs well, but is inadequate for the (hyperactive) Tenebrio molitor AFPs. We also find the engulfment resistance to be a key parameter, which depends on the protein's size. Finally, we explain intuitively how TH depends on the seeding time of the ice crystal in the protein solution. Using this insight, we explain the discrepancy in TH measurements between different assays. This article is part of the theme issue 'The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.

A Palm-Sized Cryoprobe System With a Built-In Thermocouple and Its Application in an Animal Model of Epilepsy

OBJECTIVE

The purpose of this study is to propose a palm-sized cryoprobe system with a built-in thermocouple (TC) for highly accurate and sensitive temperature measurements, and to verify the effectiveness of the system.

METHODS

Conventional cryoprobe systems based on the boiling effect of a refrigerant have triple coaxial tubes. In the proposed system, the outer and middle coaxial tubes are made of two different metals that are welded only at the probe tip, thereby forming a TC. The thermoelectric properties of the built-in TC and measurement accuracy were investigated in agar in a constant-temperature chamber. The system was also applied in a penicillin G-induced rat brain epilepsy model.

RESULTS

We verified that the built-in TC has appropriate thermoelectric properties and that the system more accurately and sensitively measured transient temperature changes at the probe tip wall compared to conventional systems, showing the cooling performance of the system. In the rat model, epileptiform activities disappeared on freezing, and reliable cell necrosis was achieved at an end temperature of -45.2 ± 1.6 °C.

CONCLUSIONS

The proposed system is suitable for reliable cryosurgery.

SIGNIFICANCE

The system is probably to be valuable for clarifying the relationship between freezing temperature and cell necrosis in vivo.

Long-term deep-supercooling of large-volume water and red cell suspensions via surface sealing with immiscible liquids

Supercooling of aqueous solutions is a fundamentally and practically important physical phenomenon with numerous applications in biopreservation and beyond. Under normal conditions, heterogeneous nucleation mechanisms critically prohibit the simultaneous long-term (> 1 week), large volume (> 1 ml), and low temperatures (< -10 °C) supercooling of aqueous solutions. Here, we report on the use of surface sealing of water by an oil phase to significantly diminish the primary heterogeneous nucleation at the water/air interface. We achieve deep supercooling (down to -20 °C) of large volumes of water (up to 100 ml) for long periods (up to 100 days) simultaneously via this approach. Since oils are mixtures of various hydrocarbons we also report on the use of pure alkanes and primary alcohols of various lengths to achieve the same. Furthermore, we demonstrate the utility of deep supercooling via preliminary studies on extended (100 days) preservation of human red blood cells.

Efficacy and Safety of Three Cryotherapy Devices for Wart Treatment: A Randomized, Controlled, Investigator-Blinded, Comparative Study

INTRODUCTION

Cutaneous warts are common skin lesions, caused by human papillomavirus. For years, liquid nitrogen is the cryogen of choice for wart treatment. Alternatively, several cryogenic devices for home treatment are commercially available. The present trial assessed efficacy and safety of a novel nitrous oxide-based cryogenic device for home use (EndWarts Freeze® in Europe, Compound W® Nitro-Freeze in the USA).

METHODS

This investigator-blinded, controlled, randomized study compared the nitrous oxide device (test product) with a dimethylether propane-based product (Wartner®; comparator 1). Subjects with common or plantar warts (50/50 ratio) were randomized into two groups (n = 58, test product; n = 40, comparator 1). Sequentially, an extra treatment arm (n = 40) was added to compare with a dimethylether-based product with metal nib (Wortie®; comparator 2). Main objective implied comparison of the percentage cured subjects after one to maximum three treatments. Efficacy and safety was evaluated by a blinded investigator.

RESULTS

After a maximum of three applications, a significantly (p = 0.001) higher cure rate of 70.7% (Intention-to-Treat analysis) was observed with test product versus 46.2% (comparator 1) and 47.5% (comparator 2). Almost three times more subjects were cured after 1 test product application (29.3%), versus comparator 1 (10.4%) and comparator 2 (12.5%). Reported side effects were transient and typical of cryotherapy. All treatments were well-tolerated.

CONCLUSION

The superior cure rates for the test product versus two comparators can be explained by its design. Combination of nitrous oxide (cooling agent), the specific activation method (holding the liquid coolant in the cap), and skin-conforming polyurethane foam, results in higher cooling efficiency (- 80 °C) and more effective wart freezing. This trial demonstrated that the nitrous oxide device is a safe, user-friendly and effective wart treatment for home use, comparing favourably to dimethylether (propane) devices with higher freezing temperature, regardless of the applicator type.

FUNDING

Oystershell Laboratories.

TRIAL REGISTRATION

Clinicaltrials.gov identifier, NCT03129373.

Metered Cryospray™: a novel uniform, controlled, and consistent in vivo application of liquid nitrogen cryogenic spray

In this article, a novel cryotherapy approach using a uniform, controlled, and consistent in vivo application of liquid nitrogen (LN₂) spray as a Metered Cryospray^™ (MCS) process is described. Although MCS may be used for many potential clinical applications, this paper focuses on the development that led to the controlled and consistent delivery of radial LN₂ cryogen spray in order to generate a uniform circumferential effect and how the amount of MCS can be adapted to specifically ablate targeted diseases within a patient’s lumen such as an airway or esophagus.

Current status of spray cryotherapy for airway disease

The use of liquid nitrogen to treat skin and mucosal lesions is well understood in the dermatologic and gastrointestinal literature. Direct spray cryotherapy (SCT) in the airway has shown promising results in the treatment of esophageal premalignant and even invasive lesions. In the airway, several studies have shown it to be a safe, effective treatment for both benign and malignant disease. It is easily administered in the outpatient setting and can be repeated several times without undue side effects. In this article, we review the current literature on the use of SCT for the treatment of endobronchial lesions and also describe our own institutional experience of the use of SCT in the airway. The use of proper technique and airway venting is important in mitigating the complications of barotrauma from massive expansion of nitrogen upon conversion from the liquid to gaseous state. We also review some of the basic science principals behind the use of the cryotherapy to treat lesions in different tissues. We feel that SCT is a potential area for further research at both clinical and basic science level.

Automated freeze-thaw cycles for decellularization of tendon tissue - a pilot study

Background

Decellularization of tendon tissue plays a pivotal role in current tissue engineering approaches for in vitro research as well as for translation of graft-based tendon restoration into clinics. Automation of essential decellularization steps like freeze-thawing is crucial for the development of more standardized decellularization protocols and commercial graft production under good manufacturing practice (GMP) conditions in the future.

Methods

In this study, a liquid nitrogen-based controlled rate freezer was utilized for automation of repeated freeze-thawing for decellularization of equine superficial digital flexor tendons. Additional tendon specimens underwent manually performed freeze-thaw cycles based on an established procedure. Tendon decellularization was completed by using non-ionic detergent treatment (Triton X-100). Effectiveness of decellularization was assessed by residual nuclei count and calculation of DNA content. Cytocompatibility was evaluated by culturing allogeneic adipose tissue-derived mesenchymal stromal cells on the tendon scaffolds.

Results

There were no significant differences in decellularization effectiveness between samples decellularized by the automated freeze-thaw procedure and samples that underwent manual freeze-thaw cycles. Further, we inferred no significant differences in the effectiveness of decellularization between two different cooling and heating rates applied in the automated freeze-thaw process. Both the automated protocols and the manually performed protocol resulted in roughly 2% residual nuclei and 13% residual DNA content. Successful cell culture was achieved with samples decellularized by automated freeze-thawing as well as with tendon samples decellularized by manually performed freeze-thaw cycles.

Conclusions

Automated freeze-thaw cycles performed by using a liquid nitrogen-based controlled rate freezer were as effective as previously described manual freeze-thaw procedures for decellularization of equine superficial digital flexor tendons. The automation of this key procedure in decellularization of large tendon samples is an important step towards the processing of large sample quantities under standardized conditions. Furthermore, with a view to the production of commercially available tendon graft-based materials for application in human and veterinary medicine, the automation of key procedural steps is highly required to develop manufacturing processes under GMP conditions.

Spray cryotherapy (SCT): institutional evolution of techniques and clinical practice from early experience in the treatment of malignant airway disease

BACKGROUND

Spray cryotherapy (SCT) was initially developed for gastroenterology (GI) endoscopic use in the esophagus. In some institutions where a device has been utilized by GI, transition to use in the airways by pulmonologists and thoracic surgeons occurred. Significant differences exist, however, in the techniques for safely using SCT in the airways.

METHODS

We describe the early experience at Walter Reed National Military Medical Center from 2011 to 2013 using SCT in patients with malignant airway disease and the evolution of our current techniques and clinical practice patterns for SCT use in patients. In November 2013 enrollment began in a multi-institutional prospective SCT registry in which we are still enrolling and will be reported on separately.

RESULTS

Twenty-seven patients that underwent 80 procedures (2.96 procedures/patient). The average age was 63 years with a range of 20 to 87 years old. The average Eastern Cooperative Oncology Group (ECOG) status was 1.26. All malignancies were advanced stage disease. All procedures were performed in the central airways. Other modalities were used in combination with SCT in 31 (39%) of procedures. Additionally 45 of the 80 (56%) procedures were performed in proximity to a silicone, hybrid, or metal stent. Three complications occurred out of the 80 procedures. All three were transient hypoxia that limited continued SCT treatments. These patients were all discharged from the bronchoscopy recovery room to their pre-surgical state.

CONCLUSIONS

SCT can be safely used for treatment of malignant airway tumor (MAT) in the airways. Understanding passive venting of the nitrogen gas produced as the liquid nitrogen changes to gas is important for safe use of the device. Complications can be minimized by adopting strict protocols to maximize passive venting and to allow for adequate oxygenation in between sprays.

The Palm-Sized Cryoprobe System Based on Refrigerant Expansion and Boiling and Its Application to an Animal Model of Epilepsy

GOAL

The purpose of this study is to propose the palm-sized cryoprobe system based on a new concept and to suggest that the freezing technique could be used for treatment of epilepsy.

METHODS

We propose herein a cryoprobe system based on the boiling effect that uses a specific refrigerants with a boiling point higher than that of liquid nitrogen yet low enough to result in cell necrosis. To evaluate and verify the effectiveness of the proposed system, cooling characteristics are investigated in agar. In addition, the system is applied to a Wistar rat brain-model, in which the epileptic activities are induced in advance by a potent epileptogenic substance.

RESULTS

The design concept yielded the following benefits: 1) the selected refrigerant promotes sealing in the tank; 2) the tank can be made as compact as possible, limited only by the volume required for the refrigerant; 3) because the tank and probe units can be separated by a nonconducting, flexible, and high-pressure tube, the tank unit can be manipulated without disturbing the probe tip with mechanical vibrations and electrical noise. Although the agar experiments, we verified that the proposed system can uniquely and reproducibly create an ice ball. Moreover, in the rat experiments in vivo, it was confirmed that penicillin G-induced epileptic activities disappeared on freezing with the proposed system.

CONCLUSIONS

The palm-sized system has desired characteristics and can apply for an animal model of epilepsy.

SIGNIFICANCE

Results of in vivo experiments suggest that cryosurgery may be an effective treatment for epilepsy.

Nonenzymatic Cryogenic Isolation of Therapeutic Cells: Novel Approach for Enzyme-Free Isolation of Pancreatic Islets Using In Situ Cryopreservation of Islets and Concurrent Selective Freeze Destruction of Acinar Tissue

Cell-based therapies, which all involve processes for procurement and reimplantation of living cells, currently rely upon expensive, inconsistent, and even toxic enzyme digestion processes. A prime example is the preparation of isolated pancreatic islets for the treatment of type 1 diabetes by transplantation. To avoid the inherent pitfalls of these enzymatic methods, we have conceptualized an alternative approach based on the hypothesis that cryobiological techniques can be used for differential freeze destruction of the pancreas (Px) to release islets that are selectively cryopreserved in situ. Pancreata were procured from juvenile pigs using approved procedures. The concept of cryoisolation is based on differential processing of the pancreas in five stages: 1) infiltrating islets in situ preferentially with a cryoprotectant (CPA) cocktail via antegrade perfusion of the major arteries; 2) retrograde ductal infusion of water to distend the acinar; 3) freezing the entire Px solid to lt; −160°C for storage in liquid nitrogen; 4) mechanically crushing and pulverizing the frozen Px into small fragments; 5) thawing the frozen fragments, filtering, and washing to remove the CPA. Finally, the filtered effluent (cryoisolate) was stained with dithizone for identification of intact islets and with Syto 13/PI for fluorescence viability testing and glucose-stimulated insulin release assessment. As predicted, the cryoisolate contained small fragments of residual tissue comprising an amorphous mass of acinar tissue with largely intact and viable (>90%) embedded islets. Islets were typically larger (range 50–500 μm diameter) than their counterparts isolated from juvenile pigs using conventional enzyme digestion techniques. Functionally, the islets from replicate cryoisolates responded to a glucose challenge with a mean stimulation index = 3.3 ± 0.7. An enzyme-free method of islet isolation relying on in situ cryopreservation of islets with simultaneous freeze destruction of acinar tissue is feasible and proposed as a new and novel method that avoids the problems associated with conventional collagenase digestion methods.

3D simulation of platelet aggregation in cryosurgery

In cryosurgery for cancer treatment, cells are injured not only by freezing but also by vascular stasis. The vascular stasis caused by thrombosis necrotizes the surrounding non-targeted cells due to the lack of oxygen and nourishment. Inhibition of thrombus formation, which is the former phase of the vascular stasis, is required to prevent damaging normal cells around a tumorDForegoing studies simulated platelet aggregation based on distance between platelets. However, in cryosurgery, temperature dependency of blood-clotting factors' activity is required to be considered. The authors constructed a three-dimensional model consisting of vascular and extra- vascular tissues, and simulated heat transform and platelet aggregation. Heat transform was analyzed by boundary fitted coordinates method, and platelet aggregation was analyzed by particle method. The probability of bonding between platelets is derived from chemical reaction kinetics. The results showed larger size of simulated thrombus on higher temperature. The simulation with varied temperature around destructed area showed platelet aggregation depending on temperature.

Consensus recommendations for the treatment of basal cell carcinomas in Gorlin syndrome with topical methylaminolaevulinate-photodynamic therapy

BACKGROUND

Patients with Gorlin syndrome develop multiple basal cell carcinomas (BCC), for which treatment is often difficult. Methylaminolevulinate-photodynamic therapy (MAL-PDT) is approved for the treatment of superficial and nodular BCCs in Canada and several European countries.

OBJECTIVES

To establish consensus recommendations for the use of MAL-PDT in patients with Gorlin syndrome.

METHODS

The Gorlin consensus panel was comprised of 7 dermatologists who had treated a total of 83 patients with Gorlin syndrome using MAL-PDT. Consensus was developed based on the personal experience of the expert and results of literature review (on PUBMED using the keywords 'MAL' and 'PDT' and 'Gorlin' or 'naevoid basal cell carcinoma syndrome').

RESULTS

Consensus was reached among the experts and the literature review identified 9 relevant reports. The experts considered MAL-PDT a generally effective and safe therapy for treatment of BCC in Gorlin syndrome. For superficial BCC (sBCC), all sizes can be treated, and in nodular BCC (nBCC), better efficacy can be achieved in thinner lesions (<2 mm in thickness). MAL-PDT treatment schedule should be performed according to labelling although in individual cases, it may be adapted and performed on a monthly basis based on clinical assessment. Follow-up should be related to frequency of recurrence, and severity, number and location of lesions. Multiple lesions and large areas may be treated during the same session; however, adequate pain management should be considered.

CONCLUSIONS

MAL-PDT is safe and effective in patients with Gorlin syndrome. Utilization of these recommendations may improve efficacy and clearance rates in this population.

The effects of freezing versus supercooling on vascular cells: implications for balloon cryoplasty

PURPOSE

To investigate the effects of supercooling, a phase whereby cells are below 0 degrees C but still in a liquid state, and freezing, the phase when cells become solid, of vascular cells in culture.

MATERIALS AND METHODS

Bovine aortic endothelial cells and smooth muscle cells were supercooled to -10 degrees C with or without freezing for 3, 30, or 60 seconds and then rewarmed to 37 degrees C for 24 hours. Viability was assessed by means of trypan blue exclusion, and apoptosis was assessed with the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay.

RESULTS

Viability of smooth muscle cells decreased 49% after freezing versus supercooling (P< .05). Endothelial cells maintained greater viability rates. A 19.5% smooth muscle cell apoptotic rate was observed after freezing, whereas smooth muscle cell supercooling yielded rates of only 11% (P< .05). A 4.17% endothelial cell apoptotic rate was observed after freezing, whereas supercooled endothelial cells yielded a 1.76% rate (P< .05).

CONCLUSIONS

Freezing results in decreased viability and increased apoptosis compared to supercooling in both cell lines. Smooth muscle cells appear more susceptible to freezing. The biologic effects of freezing on vascular cells may elucidate the mechanisms behind the enhanced patency after cryoplasty of atherosclerotic lesions.