Cholesterol implications in plasmid DNA electrotransfer: Evidence for the involvement of endocytotic pathways

The delivery of therapeutic molecules such as plasmid DNA in cells and tissues by means of electric fields holds great promise for anticancer treatment. To allow for their therapeutic action, the molecules have first to traverse the cell membrane. The mechanisms by which the electrotransferred pDNA interacts with and crosses the plasma membrane are not yet fully explained. The aim of this study is to unravel the role of cholesterol during gene electrotransfer in cells. We performed cholesterol depletion experiments and measured its effects on various steps of the electroporation process. The first two steps consisting of electropermeabilization of the plasma membrane and of pDNA interaction with it were not affected by cholesterol depletion. In contrast, gene expression decreased. Colocalization studies with endocytotic markers showed that pDNA is endocytosed with concomitant clathrin- and caveolin/raft-mediated endocytosis. Cholesterol might be involved in the pDNA translocation through the plasma membrane. This is the first direct experimental evidence of the occurrence of endocytosis in gene electrotransfer.

Diffusion-weighted MRI for verification of electroporation-based treatments

Clinical electroporation (EP) is a rapidly advancing treatment modality that uses electric pulses to introduce drugs or genes into, e.g., cancer cells. The indication of successful EP is an instant plasma membrane permeabilization in the treated tissue. A noninvasive means of monitoring such a tissue reaction represents a great clinical benefit since, in case of target miss, retreatment can be performed immediately. We propose diffusion-weighted magnetic resonance imaging (DW-MRI) as a method to monitor EP tissue, using the concept of the apparent diffusion coefficient (ADC). We hypothesize that the plasma membrane permeabilization induced by EP changes the ADC, suggesting that DW-MRI constitutes a noninvasive and quick means of EP verification. In this study we performed in vivo EP in rat brains, followed by DW-MRI using a clinical MRI scanner. We found a pulse amplitude-dependent increase in the ADC following EP, indicating that (1) DW-MRI is sensitive to the EP-induced changes and (2) the observed changes in ADC are indeed due to the applied electric field.

Electrochemotherapy for cutaneous and subcutaneous tumor lesions: a novel therapeutic approach

Electroporation uses pulsed, high-intensity electric fields to temporarily increase cell membrane permeability by creation of pores, through which small molecules, such as chemotherapeutic agents, can diffuse inside cells before they reseal. The combination of electroporation with the administration of otherwise low-permeant cytotoxic drugs is known as electrochemotherapy (ECT). The two most commonly used drugs are bleomycin and cisplatin. ECT has already been proven to be effective in diverse tumor histotypes, including melanoma and basal and squamous cell carcinoma, Kaposi sarcoma, and breast cancer, also in those cases nonresponding to classical chemotherapies or other loco-regional treatment modalities, with a good safety profile. ECT can be proposed as loco-regional therapy for disseminated cutaneous and subcutaneous tumor lesions as alternative treatment modality to conventional therapies or as palliative care, in order to improve patients' quality of life.

Cutaneous metastases from internal malignancies

Cutaneous metastases of internal malignancies still seem to occur infrequently, although medical publications report an incidence rate of up to 10.4%. Common sense, however, fosters suspicion that we might underdiagnose the problem distracted by harder striking facets of an advanced disease. With contemporary knowledge, morphology and behavior of cutaneous metastases resemble each other regardless of the site of origin. This article itemizes clinical presentations according to organ systems, specific features, and differential diagnoses. In general, the survival turned out to be less than 12 months. But incremental awareness of cutaneous metastases proclaims this paradigm insufficient. Although excision is the local treatment of choice, investigations attempt to propose tumor-specific chemotherapeutic/immunological approaches. This paper endeavors to critically review the state of the art concerning the clinic, prognosis, and therapeutic concepts.

Antivascular effects of electrochemotherapy: implications in treatment of bleeding metastases

Solid tumors of various etiologies can be treated efficiently by electrochemotherapy (ECT), a combined use of electroporation (EP) and chemotherapeutic drugs, such as bleomycin and cisplatin. EP alone and ECT in particular, induce a profound reduction in tumor blood flow, which contributes to the antitumor effect. After EP and ECT, the time course of blood flow changes and follows the same two-phase pattern. The first rapid and short-lived vasoconstriction phase is followed by the second much longer-lived phase resulting from disrupted cytoskeletal structures and a compromised barrier function of the microvascular endothelium. In the case of ECT, however, tumor vascular endothelial cells are also affected by the chemotherapeutic drug, which leads to irrecoverable damage to tumor vessels and to a further decrease in tumor blood flow within hours after application of ECT. Tumor cells surviving the direct effects of ECT are consequently exposed to lack of oxygen and nutrients and are pushed into the secondary cascade of induced cell death. Clinically, the antitumor effectiveness of ECT has been proven extensively in the treatment of melanoma metastases, with 70-80% complete responses. The antivascular effects of ECT were also exploited for palliative treatment of bleeding melanoma metastases, with immediate cessation of bleeding and very good antitumor effectiveness. The antivascular effect of ECT is of utmost importance for translation of ECT into the treatment of deep-seated tumors, especially in well vascularized organs, such as the liver, where it prevents bleeding of the treated area.

Optimizing clinical performance and geometrical robustness of a new electrode device for intracranial tumor electroporation

Current technology has limited applicability for electroporation based treatment of deep-seated tumors, and is in general, not optimized in terms of compliance with clinically relevant parameters. Here we present a novel electrode device developed for electrotransfer of antineoplastic drugs and genes to intracranial tumors in humans, and demonstrate a method to optimize the design (i.e. geometry) of the electrode device prototype to improve both clinical performance and geometrical tolerance (robustness). We have employed a semiempirical objective function based on constraints similar to those used in radiation oncology. The results show that small geometrical changes may yield a significant improvement. For example, a 2 mm displacement of 6 electrodes yields 14% better compliance with the clinical parameters, compared to the prototype, and additionally makes the electrode device less sensitive to random geometrical deviations. The method is readily applicable to other electrode configurations.

Ablation of bone cells by electroporation

Short intense electrical pulses transiently increase the permeability of the cell membrane, an effect known as electroporation. This can be combined with antiblastic drugs for ablation of tumours of the skin and subcutaneous tissue. The aim of this study was to test the efficacy of electroporation when applied to bone and to understand whether the presence of mineralised trabeculae would affect the capability of the electric field to porate the membrane of bone cells. Different levels of electrical field were applied to the femoral bone of rabbits. The field distribution and modelling were simulated by computer. Specimens of bone from treated and control rabbits were obtained for histology, histomorphometry and biomechanical testing. After seven days, the area of ablation had increased in line with the number of pulses and/or with the amplitude of the electrical field applied. The osteogenic activity in the ablated area had recovered by 30 days. Biomechanical testing showed structural integrity of the bone at both times. Electroporation using the appropriate combination of voltage and pulses induced ablation of bone cells without affecting the recovery of osteogenic activity. It can be an effective treatment in bone and when used in combination with drugs, an option for the treatment of metastases.

Robustness of treatment planning for electrochemotherapy of deep-seated tumors

Treatment of cutaneous and subcutaneous tumors with electrochemotherapy has become a regular clinical method, while treatment of deep-seated tumors is still at an early stage of development. We present a method for preparing a dedicated patient-specific, computer-optimized treatment plan for electrochemotherapy of deep-seated tumors based on medical images. The treatment plan takes into account the patient's anatomy, tissue conductivity changes during electroporation and the constraints of the pulse generator. Analysis of the robustness of a treatment plan made with this method shows that the effectiveness of the treatment is not affected significantly by small single errors in electrode positioning. However, when many errors occur simultaneously, the resulting drop in effectiveness is larger, which means that it is necessary to be as accurate as possible in electrode positioning. The largest effect on treatment effectiveness stems from uncertainties in dielectric properties and electroporation thresholds of treated tumors and surrounding tissues, which emphasizes the need for more accurate measurements and more research. The presented methods for treatment planning and robustness analysis allow quantification of the treatment reproducibility and enable the setting of suitable safety margins to improve the likelihood of successful treatment of deep-seated tumors by electrochemotherapy.

Bleomycin/interleukin-12 electrochemogene therapy for treating naturally occurring spontaneous neoplasms in dogs

On the basis of superior outcomes from electrochemogene therapy (ECGT) compared with electrochemotherapy in mice, we determined the efficacy of ECGT applied to spontaneous canine neoplasms. Intralesional bleomycin and feline interleukin-12 DNA (fIL-12 DNA) injection combined with translesional electroporation resulted in complete cure of two recurrent World Health Organization stage T(2b)N(0)M(0) oral squamous cell carcinomas (SCCs) and one T(2)N(0)M(0) acanthomatous ameloblastoma. Three remaining dogs, which had no other treatment options, had partial responses to ECGT; one had mandibular T(3b)N(2b)M(1) melanoma with pulmonary and lymph node metastases; one had cubital T(3)N(0)M(1) histiocytic sarcoma with spleen metastases; and one had soft palate T(3)N(0)M(0) fibrosarcoma. The melanoma dog had decrease in size of the primary tumor before recrudescence and euthanasia. The histiocytic sarcoma dog had resolution of the primary tumor, but was euthanized because of metastases 4 months after the only treatment. The dog with T(3)N(0)M(0) fibrosarcoma had tumor regression with recrudescence. Treatment was associated with minimal side effects and was easy to perform. It was associated with repair of bone lysis in cured dogs, it improved quality of life of dogs with partial responses and extended overall survival time. ECGT seems to be a safe and resulted in complete responses in SCC and acanthomatous ameloblastoma.

Long-term results of melphalan-based isolated limb perfusion with or without low-dose TNF for in-transit melanoma metastases

BACKGROUND

The aims of the study were: (1) to determine toxicity, response rate, local-regional control, and survival in the entire population of the perfused patients; (2) to compare toxicity, response, and survival among patients who underwent melphalan-based perfusion with or without low-dose tumor necrosis factor (TNF); and (3) to identify factors that predict a complete response and survival.

MATERIALS AND METHODS

A total of 53 patients with extensive in-transit metastases (47%) underwent perfusion with melphalan, and 59 (53%) also received low-dose TNF.

RESULTS

No difference was observed between the 2 drug regimens for what concerns local toxicity (P = 1.0). The tumor complete response rate was higher in patients treated with TNF (60.3% versus 41.5%, P = .036), in particular in the case of locally advanced tumors (66.7% versus 30%, P = .049). The presence of lymph node metastases had a negative influence on the tumor response rate (P = .003). Median time to local progression and survival were 19.6 and 34.5 months, respectively. Long-term complete response was achieved in 68% of the patients with initial CR (39 of 57 patients). The tumor response after perfusion was the only prognostic factor for local control and survival (P < .0001 and P = .002, respectively).

CONCLUSIONS

In the case of locally advanced disease, the addition of low-dose TNF to melphalan-based isolated limb perfusion appears safe and particularly useful. The presence of lymph node metastases is associated with decreased response rates. A sustained complete response was obtained in about one-third of the patients.

Bleomycin/interleukin-12 electrochemogenetherapy for treating naturally occurring spontaneous neoplasms in dogs

On the basis of superior outcomes from electrochemogenetherapy (ECGT) compared with electrochemotherapy in mice, we determined the efficacy of ECGT applied to spontaneous canine neoplasms. Intralesional bleomycin (BLM) and feline interleukin-12 DNA injection combined with translesional electroporation resulted in complete cure of two recurrent World Health Organization stage T(2b)N(0)M(0) oral squamous cell carcinomas (SCCs) and one T(2)N(0)M(0) acanthomatous ameloblastoma. Three remaining dogs, which had no other treatment options, had partial responses to ECGT; one had mandibular T(3b)N(2b)M(1) melanoma with pulmonary and lymph node metastases; one had cubital T(3)N(0)M(1) histiocytic sarcoma with spleen metastases; and one had soft palate T(3)N(0)M(0) fibrosarcoma. The melanoma dog had decrease in the size of the primary tumor before recrudescence and euthanasia. The histiocytic sarcoma dog had resolution of the primary tumor, but was euthanized because of metastases 4 months after the only treatment. The dog with T(3)N(0)M(0) fibrosarcoma had tumor regression with recrudescence. Treatment was associated with minimal side effects and was easy to perform, was associated with repair of bone lysis in cured dogs, improved quality of life for dogs with partial responses and extended overall survival time. ECGT seems to be a safe and resulted in complete responses in SCC and acanthomatous ameloblastoma.

Clinicopathological parameters, recurrence, locoregional and distant metastasis in 115 T1-T2 oral squamous cell carcinoma patients

The incidence of oral squamous cell carcinoma remains high. Oral and oro-pharyngeal carcinomas are the sixth most common cancer in the world. Several clinicopathological parameters have been implicated in prognosis, recurrence and survival, following oral squamous cell carcinoma. In this retrospective analysis, clinicopathological parameters of 115 T1/T2 OSCC were studied and compared to recurrence and death from tumour-related causes.

The study protocol was approved by the Joint UCL/UCLH committees of the ethics for human research. The patients' data was entered onto proformas, which were validated and checked by interval sampling. The fields included a range of clinical, operative and histopathological variables related to the status of the surgical margins. Data collection also included recurrence, cause of death, date of death and last clinic review. Causes of death were collated in 4 categories (1) death from locoregional spread, (2) death from distant metastasis, (3) death from bronchopulmonary pneumonia, and (4) death from any non-tumour event that lead to cardiorespiratory failure.

The patients' population comprised 65 males and 50 females. Their mean age at the 1^st diagnosis of OSCC was 61.7 years. Two-thirds of the patients were Caucasians. Primary sites were mainly identified in the tongue, floor of mouth (FOM), buccal mucosa and alveolus. Most of the identified OSCCs were low-risk (T1N0 and T2N0). All patients underwent primary resection ± neck dissection and reconstruction when necessary. Twenty-two patients needed adjuvant radiotherapy. Pathological analysis revealed that half of the patients had moderately differentiated OSCC. pTNM slightly differed from the cTNM and showed that 70.4% of the patients had low-risk OSCC. Tumour clearance was ultimately achieved in 107 patients. Follow-up resulted in a 3-year survival of 74.8% and a 5-year survival of 72.2%.

Recurrence was identified in 23 males and 20 females. The mean age of 1^st diagnosis of the recurrence group was 59.53 years. Most common oral sites included the lateral border of tongue and floor of mouth. Recurrence was associated with clinical N-stage disease. The surgical margins in this group was evaluated and found that 17 had non-cohesive invasion, 30 had dysplasia at margin, 21 had vascular invasion, 9 had nerve invasion and 3 had bony invasion. Severe dysplasia was present in 37 patients. Tumour clearance was achieved in only 8 patients. The mean depth of tumour invasion in the recurrence group was 7.6 mm.

An interesting finding was that 5/11 patients who died of distant metastasis had their primary disease in the tongue. Nodal disease comparison showed that 8/10 patients who died of locoregional metastasis and 8/11 patients who died from distant metastasis had clinical nodal involvement. Comparing this to pathological nodal disease (pTNM) showed that 10/10 patients and 10/11 patients who died from locoregional and distant metastasis, respectively, had nodal disease. All patients who died from locoregional and distant metastasis were shown to have recurrence after the primary tumour resection.

Squamous cell carcinoma of the oral cavity has a poor overall prognosis with a high tendency to recur at the primary site and extend to involve the cervical lymph nodes. Several clinicopathological parameters can be employed to assess outcome, recurrence and overall survival.

Towards treatment planning and treatment of deep-seated solid tumors by electrochemotherapy

Background

Electrochemotherapy treats tumors by combining specific chemotherapeutic drugs with an intracellular target and electric pulses, which increases drug uptake into the tumor cells. Electrochemotherapy has been successfully used for treatment of easily accessible superficial tumor nodules. In this paper, we present the first case of deep-seated tumor electrochemotherapy based on numerical treatment planning.

Methods

The aim of our study was to treat a melanoma metastasis in the thigh of a patient. Treatment planning for electrode positioning and electrical pulse parameters was performed for two different electrode configurations: one with four and another with five long needle electrodes. During the procedure, the four electrode treatment plan was adopted and the patient was treated accordingly by electrochemotherapy with bleomycin. The response to treatment was clinically and radiographically evaluated. Due to a partial response of the treated tumor, the metastasis was surgically removed after 2 months and pathological analysis was performed.

Results

A partial response of the tumor to electrochemotherapy was obtained. Histologically, the metastasis showed partial necrosis due to electrochemotherapy, estimated to represent 40-50% of the tumor. Based on the data obtained, we re-evaluated the electrical treatment parameters in order to correlate the treatment plan with the clinical response. Electrode positions in the numerical model were updated according to the actual positions during treatment. We compared the maximum value of the measured electric current with the current predicted by the model and good agreement was obtained. Finally, tumor coverage with an electric field above the reversible threshold was recalculated and determined to be approximately 94%. Therefore, according to the calculations, a small volume of tumor cells remained viable after electrochemotherapy, and these were sufficient for tumor regrowth.

Conclusions

In this, the first reported clinical case, deep-seated melanoma metastasis in the thigh of the patient was treated by electrochemotherapy, according to a treatment plan obtained by numerical modeling and optimization. Although only a partial response was obtained, the presented work demonstrates that treatment of deep-seated tumor nodules by electrochemotherapy is feasible and sets the ground for numerical treatment planning-based electrochemotherapy.

Trial registration

EudraCT:2008-008290-54

Direct gene therapy for bone regeneration: gene delivery, animal models, and outcome measures

While various problems with bone healing remain, the greatest clinical change is the absence of an effective approach to manage large segmental defects in limbs and craniofacial bones caused by trauma or cancer. Thus, nontraditional forms of medicine, such as gene therapy, have been investigated as a potential solution. The use of osteogenic genes has shown great potential in bone regeneration and fracture healing. Several methods for gene delivery to the fracture site have been described. The majority of them include a cellular component as the carrying vector, an approach known as cell-mediated gene therapy. Yet, the complexity involved with cell isolation and culture emphasizes the advantages of direct gene delivery as an alternative strategy. Here we review the various approaches of direct gene delivery for bone repair, the choice of animal models, and the various outcome measures required to evaluate the efficiency and safety of each technique. Special emphasis is given to noninvasive, quantitative, in vivo monitoring of gene expression and biodistribution in live animals. Research efforts should aim at inducing a transient, localized osteogenic gene expression within a fracture site to generate an effective therapeutic approach that would eventually lead to clinical use.

Electrochemotherapy of melanoma cutaneous metastases

Az elektrokemoterápia daganatok bőráttéteinek palliatív kezelésére alkalmas eljárás, amelynek során nagy energiájú elektromos impulzusok hatására a sejtek membránja áteresztővé válik olyan anyagok, így kemoterapeutikumok számára, amelyek egyébként nem vagy csak kismértékben kerülnének a sejt belsejébe, ezáltal megnövelve azok citotoxikus hatását. Módszer: Klinikánkon 7, előrehaladott melanomában szenvedő beteg 81 bőráttétének elektrokemoterápiás kezelését végeztük el. A beavatkozásokat altatásban, intravénás bleomycin adásával végeztük. Az átlagos követési idő 218 nap volt. Eredmények: A kezelés hatására 25%-ban észleltünk teljes, míg 43%-ban részleges remissziót. A kezelt metasztázisok 26%-ánál nem történt változás, míg 6%-ban a tumor növekedett. Következtetések: Eredményeink alátámasztják azokat az irodalmi adatokat, amelyek szerint az elektrokemoterápia egyszerűen kivitelezhető, hatásos módszer a melanoma többszörös bőráttéteinek palliatív kezelésére. Az új eljárás kevés mellékhatással jár, és javítja a betegek életminőségét.

Electric pulses used in electrochemotherapy and electrogene therapy do not significantly change the expression profile of genes involved in the development of cancer in malignant melanoma cells

Background

Electroporation is a versatile method for in vitro or in vivo delivery of different molecules into cells. However, no study so far has analysed the effects of electric pulses used in electrochemotherapy (ECT pulses) or electric pulses used in electrogene therapy (EGT pulses) on malignant cells. We studied the effect of ECT and EGT pulses on human malignant melanoma cells in vitro in order to understand and predict the possible effect of electric pulses on gene expression and their possible effect on cell behaviour.

Methods

We used microarrays with 2698 different oligonucleotides to obtain the expression profile of genes involved in apoptosis and cancer development in a malignant melanoma cell line (SK-MEL28) exposed to ECT pulses and EGT pulses.

Results

Cells exposed to ECT pulses showed a 68.8% average survival rate, while cells exposed to EGT pulses showed a 31.4% average survival rate. Only seven common genes were found differentially expressed in cells 16 h after exposure to ECT and EGT pulses. We found that ECT and EGT pulses induce an HSP70 stress response mechanism, repress histone protein H4, a major protein involved in chromatin assembly, and down-regulate components involved in protein synthesis.

Conclusion

Our results show that electroporation does not significantly change the expression profile of major tumour suppressor genes or oncogenes of the cell cycle. Moreover, electroporation also does not changes the expression of genes involved in the stability of DNA, supporting current evidence that electroporation is a safe method that does not promote tumorigenesis. However, in spite of being considered an isothermal method, it does to some extent induce stress, which resulted in the expression of the environmental stress response mechanism, HSP70.