The 16th Annual Scientific Meeting of the Society for Neuro-Oncology in Conjunction with the AANS... more The 16th Annual Scientific Meeting of the Society for Neuro-Oncology in Conjunction with the AANS/CNS Section on Tumors, Orange County, California, USA, 17-20 November 2011. In Neuro-Oncology, 2011, v. 13 n. Suppl. 3, p. iii111, abstract no. ET-18
3D printing is an additive manufacturing method that involves successive deposition of layers of ... more 3D printing is an additive manufacturing method that involves successive deposition of layers of materials to create a construct from a digital model. 3D-printing technologies have widespread applications in medicine and are increasingly used for solving a wide variety of medical problems. In this review, we summarize existing 3D-printing technologies and explore recent advances in the development and characterization of bioinks and biomaterial inks. We will then explain characterization methods for determining the rheological and mechanical properties of printing inks and 3D-printed constructs using invasive and noninvasive methods. Lastly, four core uses in recent innovations in medicine, including tissue and organoid engineering, disease modeling, drug delivery, biosensing, patient-specific implants and challenges along with future prospects will be discussed.
Systemically administered chemotherapy reduces the efficiency of the anticancer agent at the targ... more Systemically administered chemotherapy reduces the efficiency of the anticancer agent at the target tumor tissue and results in distributed drug to non-target organs, inducing negative side effects commonly associated with chemotherapy and necessitating repeated administration. Injectable hydrogels present themselves as a potential platform for non-invasive local delivery vehicles that can serve as a slow-releasing drug depot that fills tumor vasculature, tissue, or resection cavities. Herein, we have systematically formulated and tested an injectable shear-thinning hydrogel (STH) with a highly manipulable release profile for delivering doxorubicin, a common chemotherapeutic. By detailed characterization of the STH physical properties and degradation and release dynamics, we selected top candidates for testing in cancer models of increasing biomimicry. Two-dimensional cell culture, tumor-on-a-chip, and small animal models were used to demonstrate the high anticancer potential and re...
Les études de protéomique fonctionnelle nous indiquent que probablement aucune protéine n'acc... more Les études de protéomique fonctionnelle nous indiquent que probablement aucune protéine n'accomplit une activité biologique ou acquiert sa conformation active de façon complètement autonome. La fonctionnalité des protéines est donc acquise via les interactions protéine-protéine. Pensons par exemples aux interactions protéine-protéine impliquées dans les cascades de signalisation cellulaire, aux complexes de transcription, de traduction etc. Vu la réelle importance des interactions protéine-protéine, la recherche en biologie est présentement en mouvance vers un nouveau courant, soit l'étude des interactions protéiniques ou l'interactomique. Les interactions inter protéine impliquant des super-hélices ont été étudiées chez la levure et il a été avancé qu'une protéine sur 11 interagirait avec d'autres protéines en utilisant un domaine structuré en super-hélice. Plus de 5% des cadres de lecture ouvert (ORFs) du génome de la levure détiendrait l'information modula...
Infiltrated glioblastoma (GBM) cells into the brain parenchyma cause recurrences after tumor rese... more Infiltrated glioblastoma (GBM) cells into the brain parenchyma cause recurrences after tumor resection and there is presently no efficient non-invasive method to detect these infiltrated cells. One obstacle is the blood-brain barrier (BBB), which limits the passage of specific radiolabeled antibodies targeting infiltrated cells to the central nervous system, preventing imaging by positron emission tomography (PET). We hereby aimed to conceive bispecific radiolabeled antibodies acting in two chronological steps: 1-targeting a transporter to allow receptor-mediated transcytosis through the BBB and 2-targeting a specific biomarker of GBM cells for a specific retention and imaging. We will present the first part of the project consisting to demonstrate that the mono-specific radiolabeled antibody targeting BBB-transporter can actively cross the BBB of healthy rat following injection in the right external carotid artery. This method allows for high tracer concentration in the right hemisphere after first passage following the injection. Comparing the specific radiolabeled antibody to a non-specific antibody, we observe that only the BBB-transmigrating antibody is momentary retained at the BBB and then returns in the blood circulation. We will next assess whether this transitory uptake to the BBB is sufficient to let the bi-specific antibody reaches and link a specific antigen present on the migrating GBM cells. This study demonstrates that our radiolabeled antibody allows for a transitory and specific uptake to the BBB. These successful results are promising for the use of bi-specific radiolabeled antibody targeting infiltrated GBM cells thus should enabling for specific PET imaging.
Chemoattraction is a normal and essential process, but it can also be involved in tumorigenesis. ... more Chemoattraction is a normal and essential process, but it can also be involved in tumorigenesis. This phenomenon plays a key role in glioblastoma (GBM). The GBM tumor cells are extremely difficult to eradicate, due to their strong capacity to migrate into the brain parenchyma. Consequently, a complete resection of the tumor is rarely a possibility, and recurrence is inevitable. To overcome this problem, we proposed to exploit this behavior by using three chemoattractants: CXCL10, CCL2 and CCL11, released by a biodegradable hydrogel (GlioGel) to produce a migration of tumor cells toward a therapeutic trap. To investigate this hypothesis, the agarose drop assay was used to test the chemoattraction capacity of these three chemokines on murine F98 and human U87MG cell lines. We then studied the potency of this approach in vivo in the well-established syngeneic F98-Fischer glioma-bearing rat model using GlioGel containing different mixtures of the chemoattractants. In vitro assays result...
A liposomal formulation of gold nanoparticles (GNPs) and carboplatin, named LipoGold, was produce... more A liposomal formulation of gold nanoparticles (GNPs) and carboplatin, named LipoGold, was produced with the staggered herringbone microfluidic method. The radiosensitizing potential of LipoGold and similar concentrations of non-liposomal GNPs, carboplatin and oxaliplatin was evaluated in vitro with the human colorectal cancer cell line HCT116 in a clonogenic assay. Progression of HCT116 tumor implanted subcutaneously in NU/NU mice was monitored after an irradiation of 10 Gy combined with either LipoGold, GNPs or carboplatin injected directly into the tumor by convection-enhanced delivery. Radiosensitization by GNPs alone or carboplatin alone was observed only at high concentrations of these compounds. Furthermore, low doses of carboplatin alone or a combination of carboplatin and GNPs did not engender radiosensitization. However, the same low doses of carboplatin and GNPs administered simultaneously by encapsulation in liposomal nanocarriers (LipoGold) led to radiosensitization and ...
BACKGROUND Glioblastoma (GBM) is a devastating disease with a median survival of 14–16 months. Th... more BACKGROUND Glioblastoma (GBM) is a devastating disease with a median survival of 14–16 months. This poor prognosis can be explained by 3 factors. First, the infiltrative nature of the disease prohibits a complete removal of the tumor. Second, some of the tumor cells are brain tumor stem cells, which are highly migratory and highly resistant to treatments. Finally, the presence of the blood-brain barrier prohibits entry of therapeutics. This situation implies that new treatment approaches must be directed toward the infiltrated brain surrounding the resection cavity. To bypass this problem and improve the potency of adjuvant treatment, we have designed a new “GlioGel-device” that will have the ability to: 1- attract the migrating tumor cells into or nearby the device, and 2- subsequently deliver chemotherapy to the locally pooled tumor cells and 3- irradiate these cells with radioisotopes embedded in the GlioGel. MATERIAL AND METHODS In vitro proof of principle of chemoattraction was...
Background: Effectiveness of chemotherapy for treating glioblastoma (GBM) brain tumors is hampere... more Background: Effectiveness of chemotherapy for treating glioblastoma (GBM) brain tumors is hampered by the blood-brain barrier which limits the entry into the brain of most drugs from the blood. To bypass this barrier, convection-enhanced delivery (CED) was proposed to directly inject drugs in tumor. However, the benefit of CED may be hampered when drugs diffuse outside the tumor to then induce neurotoxicity. Encapsulation of drugs into liposome aims at increasing tumor cells specificity and reduces neurotoxicity. However, the most appropriate liposomal formulation to inject drugs into brain tumor by CED still remains to be determined. In this study, four liposomal carboplatin formulations were prepared and tested in vitro on F98 glioma cells and in Fischer rats carrying F98 tumor implanted in the brain. Impact of pegylation on liposomal surface and relevance of positive or negative charge were assessed. Results: The cationic non-pegylated (L1) and pegylated (L2) liposomes greatly improved the toxicity of carboplatin in vitro compared to free carboplatin, whereas only a modest improvement and even a reduction of efficiency were measured with the anionic non-pegylated (L3) and the pegylated (L4) liposomes. Conversely, only the L4 liposome significantly increased the median survival time of Fisher rats implanted with the F98 tumor, compared to free carboplatin. Neurotoxicity assays performed with the empty L4′ liposome showed that the lipid components of L4 were not toxic. These results suggest that the positive charge on liposomes L1 and L2, which is known to promote binding to cell membrane, facilitates carboplatin accumulation in cancer cells explaining their higher efficacy in vitro. Conversely, negatively charged and pegylated liposome (L4) seems to diffuse over a larger distance in the tumor, and consequently significantly increased the median survival time of the animals. Conclusions: Selection of the best liposomal formulation based on in vitro studies or animal model can result in contradictory conclusions. The negatively charged and pegylated liposome (L4) which was the less efficient formulation in vitro showed the best therapeutic effect in animal model of GBM. These results support that relevant animal model of GBM must be considered to determine the optimal physicochemical properties of liposomal formulations.
Radiation stimulates the expression of inflammatory mediators known to increase cancer cell invas... more Radiation stimulates the expression of inflammatory mediators known to increase cancer cell invasion. Therefore, it is important to determine whether anti-inflammatory drugs can prevent this adverse effect of radiation. Since cyclooxygenase-2 (COX-2) is a central player in the inflammatory response, we performed studies to determine whether the COX-2 inhibitor NS-398 can reduce the radiation enhancement of cancer cell invasion. Thighs of Balb/c mice treated with NS-398 were irradiated with either daily fractions of 7.5 Gy for five consecutive days or a single 30 Gy dose prior to subcutaneous injection of nonirradiated MC7-L1 mammary cancer cells. Five weeks later, tumor invasion, blood vessel permeability and interstitial volumes were assessed using magnetic resonance imaging (MRI). Matrix metalloproteinase-2 (MMP-2) was measured in tissues by zymography at 21 days postirradiation. Cancer cell invasion in the mouse thighs was increased by 12-fold after fractionated irradiations (5 ×...
Irradiation of brain stimulates the expression of inflammatory mediators, some of which can modif... more Irradiation of brain stimulates the expression of inflammatory mediators, some of which can modify the ability of cancer cells to infiltrate the brain. In the present study, the time window during which this stimulation occurs was determined. Brain of Fischer rat was irradiated (15 Gy) and expression of pro-inflammatory mediators IL-1β, IL-6 and TNF-α was measured from 4 h to 20 days post-irradiation. Level of the matrix metalloproteinase 2 (MMP-2) and prostaglandin E2 (PGE2) which can favor cancer cell infiltration were also measured. The F98 glioma cells were implanted either during (4 h post-irradiation) or after (10 days post-irradiation) the pro-inflammatory phase. Infiltration distance of F98 cells in brain parenchyma and the median survival time of the animals were determined. Expression of IL-1β, IL-6 and TNF-α was significantly increased in the irradiated brains with a peak at 4 h post-irradiation. Implantation of F98 glioma cells 4 h post-irradiation reduced the median survival time of Fischer rats to 18 days, compared to 25 days when the F98 were implanted in non-irradiated brain. Irradiation of the brain increased the distance of infiltration of F98 cells and was associated with increased levels of MMP-2 and PGE2. Conversely, F98 cells implanted 10 days post-irradiation have infiltrated the brain over a shorter distance and the median survival time of rats was increased to 35 days. Cancer recurrence is frequently observed in GBM patients. A better understanding of the inflammatory response observed in irradiated brain could contribute to develop new therapeutic modalities to further increase the efficiency of radiotherapy.
Targeted and whole-brain irradiation in humans can result in significant side effects causing dec... more Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The purpose of this work is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. Methods: Euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomography (CT), to estimate positioning variations relative to the bregma skull reference point. Using a rat brain atlas and the stereotactic bregma coordinates obtained from CT images, different regions of the brain were delimited and a treatment plan was generated. A single isocenter treatment plan delivering ≥100 Gy in 100% of the target volume was produced by Leksell GammaPlan using the 4 mm diameter collimator of sectors 4, 5, 7, and 8 of the Gamma Knife unit. Impact of positioning deviations of the rat brain on dose deposition was simulated by GammaPlan and validated with dosimetric measurements. Results: The authors' results showed that 90% of the target volume received 100 ± 8 Gy and the maximum of deposited dose was 125 ± 0.7 Gy, which corresponds to an excellent relative standard deviation of 0.6%. This dose deposition calculated with GammaPlan was validated with dosimetric films resulting in a dose-profile agreement within 5%, both in X-and Z-axes. Conclusions: The authors' results demonstrate the feasibility of standardizing the irradiation procedure of a small volume in the rat brain using a Gamma Knife.
Treatment of glioblastoma with platinum compounds modestly improves progression-free survival and... more Treatment of glioblastoma with platinum compounds modestly improves progression-free survival and may cause toxic effects which prevent use at higher dose that would otherwise improve the antineoplastic effect. To reduce toxicity, we propose to encapsulate the platinum drug in a liposome. We have also tested three methods of drug administration (intra-venous, intra-arterial and intra-arterial combined with blood brain barrier disruption) to determine which one optimizes the tumor cell uptake, limits the toxicity and delivers the best concomitance effect with radiotherapy. Cisplatin, oxaliplatin, their respective liposomal formulations, Lipoplatin TM and Lipoxal TM , and carboplatin were assessed in F98 glioma, orthotopically implanted in Fischer rats. We found that the modest accumulation of drugs in tumor cells after intravenous injection was significantly improved when the intra-arterial route was used and further increased after the transient opening of the blood brain barrier with mannitol. The liposomal formulations have largely reduced the toxicity and have allowed a better exploitation of the anticancer activity of platinum agent. Although the liposomes Lipoplatin TM and Lipoxal TM have shown a similar ability to that of carboplatin, to accumulate in brain tumors, the highest additive effect with radiotherapy was obtained with carboplatin. We conclude that the intra-arterial infusion of carboplatin or Lipoxal TM in concomitance with radiation therapy leads to the best tumor control as measured by an increase of mean survival time in Fischer rats implanted with the F98 glioma with a benefit in survival time of 13.4 and 6.5 days respectively compared to intravenous .
Despite significant advances, the radiotherapy and chemotherapy protocols marginally improve the ... more Despite significant advances, the radiotherapy and chemotherapy protocols marginally improve the overall survival of patients with glioblastoma. Lipoplatin ™ , and Lipoxal ™ , the liposomal formulations of cisplatin and oxaliplatin respectively, were tested on the F98 glioma cells for their ability to improve the cell uptake and increase the synergic effect when combined with ionizing radiation. The cytotoxicity and synergic effect of platinum compounds were assessed by colony formation assay, while the cellular uptake was measured by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). After 4 h exposure with platinum compounds, cells were irradiated (1.5 to 6.6 Gy) with a 60 Co source. The liposomal formulations were compared to their liposome-free analogs and to carboplatin. The concomitant treatment of F98 cells with carboplatin and radiation produced the highest radiosensitizing effect (30-fold increase). Among the platinum compounds tested, Lipoplatin ™ produced the most promising results. This liposomal formulation of cisplatin improved the cell uptake by 3-fold, and its radiosensitizing potential was enhanced by 14-fold. Although Lipoxal ™ can potentially reduce the adverse effect of oxaliplatin, a synergic effect with radiation was measured only when incubated at a concentration higher than its IC50. Conversely, concomitant treatment with cisplatin did not result in a synergic effect, as in fact a radioprotective effect was measured on the F98 cells. In conclusion, among the five platinum compounds tested, carboplatin and Lipoplatin ™ showed the best radiosensitizing effect. Lipoplatin ™ seems the most promising since it led to the best cellular incorporation and has already been reported to be less neurotoxic than other platinum compounds.
The 16th Annual Scientific Meeting of the Society for Neuro-Oncology in Conjunction with the AANS... more The 16th Annual Scientific Meeting of the Society for Neuro-Oncology in Conjunction with the AANS/CNS Section on Tumors, Orange County, California, USA, 17-20 November 2011. In Neuro-Oncology, 2011, v. 13 n. Suppl. 3, p. iii111, abstract no. ET-18
3D printing is an additive manufacturing method that involves successive deposition of layers of ... more 3D printing is an additive manufacturing method that involves successive deposition of layers of materials to create a construct from a digital model. 3D-printing technologies have widespread applications in medicine and are increasingly used for solving a wide variety of medical problems. In this review, we summarize existing 3D-printing technologies and explore recent advances in the development and characterization of bioinks and biomaterial inks. We will then explain characterization methods for determining the rheological and mechanical properties of printing inks and 3D-printed constructs using invasive and noninvasive methods. Lastly, four core uses in recent innovations in medicine, including tissue and organoid engineering, disease modeling, drug delivery, biosensing, patient-specific implants and challenges along with future prospects will be discussed.
Systemically administered chemotherapy reduces the efficiency of the anticancer agent at the targ... more Systemically administered chemotherapy reduces the efficiency of the anticancer agent at the target tumor tissue and results in distributed drug to non-target organs, inducing negative side effects commonly associated with chemotherapy and necessitating repeated administration. Injectable hydrogels present themselves as a potential platform for non-invasive local delivery vehicles that can serve as a slow-releasing drug depot that fills tumor vasculature, tissue, or resection cavities. Herein, we have systematically formulated and tested an injectable shear-thinning hydrogel (STH) with a highly manipulable release profile for delivering doxorubicin, a common chemotherapeutic. By detailed characterization of the STH physical properties and degradation and release dynamics, we selected top candidates for testing in cancer models of increasing biomimicry. Two-dimensional cell culture, tumor-on-a-chip, and small animal models were used to demonstrate the high anticancer potential and re...
Les études de protéomique fonctionnelle nous indiquent que probablement aucune protéine n'acc... more Les études de protéomique fonctionnelle nous indiquent que probablement aucune protéine n'accomplit une activité biologique ou acquiert sa conformation active de façon complètement autonome. La fonctionnalité des protéines est donc acquise via les interactions protéine-protéine. Pensons par exemples aux interactions protéine-protéine impliquées dans les cascades de signalisation cellulaire, aux complexes de transcription, de traduction etc. Vu la réelle importance des interactions protéine-protéine, la recherche en biologie est présentement en mouvance vers un nouveau courant, soit l'étude des interactions protéiniques ou l'interactomique. Les interactions inter protéine impliquant des super-hélices ont été étudiées chez la levure et il a été avancé qu'une protéine sur 11 interagirait avec d'autres protéines en utilisant un domaine structuré en super-hélice. Plus de 5% des cadres de lecture ouvert (ORFs) du génome de la levure détiendrait l'information modula...
Infiltrated glioblastoma (GBM) cells into the brain parenchyma cause recurrences after tumor rese... more Infiltrated glioblastoma (GBM) cells into the brain parenchyma cause recurrences after tumor resection and there is presently no efficient non-invasive method to detect these infiltrated cells. One obstacle is the blood-brain barrier (BBB), which limits the passage of specific radiolabeled antibodies targeting infiltrated cells to the central nervous system, preventing imaging by positron emission tomography (PET). We hereby aimed to conceive bispecific radiolabeled antibodies acting in two chronological steps: 1-targeting a transporter to allow receptor-mediated transcytosis through the BBB and 2-targeting a specific biomarker of GBM cells for a specific retention and imaging. We will present the first part of the project consisting to demonstrate that the mono-specific radiolabeled antibody targeting BBB-transporter can actively cross the BBB of healthy rat following injection in the right external carotid artery. This method allows for high tracer concentration in the right hemisphere after first passage following the injection. Comparing the specific radiolabeled antibody to a non-specific antibody, we observe that only the BBB-transmigrating antibody is momentary retained at the BBB and then returns in the blood circulation. We will next assess whether this transitory uptake to the BBB is sufficient to let the bi-specific antibody reaches and link a specific antigen present on the migrating GBM cells. This study demonstrates that our radiolabeled antibody allows for a transitory and specific uptake to the BBB. These successful results are promising for the use of bi-specific radiolabeled antibody targeting infiltrated GBM cells thus should enabling for specific PET imaging.
Chemoattraction is a normal and essential process, but it can also be involved in tumorigenesis. ... more Chemoattraction is a normal and essential process, but it can also be involved in tumorigenesis. This phenomenon plays a key role in glioblastoma (GBM). The GBM tumor cells are extremely difficult to eradicate, due to their strong capacity to migrate into the brain parenchyma. Consequently, a complete resection of the tumor is rarely a possibility, and recurrence is inevitable. To overcome this problem, we proposed to exploit this behavior by using three chemoattractants: CXCL10, CCL2 and CCL11, released by a biodegradable hydrogel (GlioGel) to produce a migration of tumor cells toward a therapeutic trap. To investigate this hypothesis, the agarose drop assay was used to test the chemoattraction capacity of these three chemokines on murine F98 and human U87MG cell lines. We then studied the potency of this approach in vivo in the well-established syngeneic F98-Fischer glioma-bearing rat model using GlioGel containing different mixtures of the chemoattractants. In vitro assays result...
A liposomal formulation of gold nanoparticles (GNPs) and carboplatin, named LipoGold, was produce... more A liposomal formulation of gold nanoparticles (GNPs) and carboplatin, named LipoGold, was produced with the staggered herringbone microfluidic method. The radiosensitizing potential of LipoGold and similar concentrations of non-liposomal GNPs, carboplatin and oxaliplatin was evaluated in vitro with the human colorectal cancer cell line HCT116 in a clonogenic assay. Progression of HCT116 tumor implanted subcutaneously in NU/NU mice was monitored after an irradiation of 10 Gy combined with either LipoGold, GNPs or carboplatin injected directly into the tumor by convection-enhanced delivery. Radiosensitization by GNPs alone or carboplatin alone was observed only at high concentrations of these compounds. Furthermore, low doses of carboplatin alone or a combination of carboplatin and GNPs did not engender radiosensitization. However, the same low doses of carboplatin and GNPs administered simultaneously by encapsulation in liposomal nanocarriers (LipoGold) led to radiosensitization and ...
BACKGROUND Glioblastoma (GBM) is a devastating disease with a median survival of 14–16 months. Th... more BACKGROUND Glioblastoma (GBM) is a devastating disease with a median survival of 14–16 months. This poor prognosis can be explained by 3 factors. First, the infiltrative nature of the disease prohibits a complete removal of the tumor. Second, some of the tumor cells are brain tumor stem cells, which are highly migratory and highly resistant to treatments. Finally, the presence of the blood-brain barrier prohibits entry of therapeutics. This situation implies that new treatment approaches must be directed toward the infiltrated brain surrounding the resection cavity. To bypass this problem and improve the potency of adjuvant treatment, we have designed a new “GlioGel-device” that will have the ability to: 1- attract the migrating tumor cells into or nearby the device, and 2- subsequently deliver chemotherapy to the locally pooled tumor cells and 3- irradiate these cells with radioisotopes embedded in the GlioGel. MATERIAL AND METHODS In vitro proof of principle of chemoattraction was...
Background: Effectiveness of chemotherapy for treating glioblastoma (GBM) brain tumors is hampere... more Background: Effectiveness of chemotherapy for treating glioblastoma (GBM) brain tumors is hampered by the blood-brain barrier which limits the entry into the brain of most drugs from the blood. To bypass this barrier, convection-enhanced delivery (CED) was proposed to directly inject drugs in tumor. However, the benefit of CED may be hampered when drugs diffuse outside the tumor to then induce neurotoxicity. Encapsulation of drugs into liposome aims at increasing tumor cells specificity and reduces neurotoxicity. However, the most appropriate liposomal formulation to inject drugs into brain tumor by CED still remains to be determined. In this study, four liposomal carboplatin formulations were prepared and tested in vitro on F98 glioma cells and in Fischer rats carrying F98 tumor implanted in the brain. Impact of pegylation on liposomal surface and relevance of positive or negative charge were assessed. Results: The cationic non-pegylated (L1) and pegylated (L2) liposomes greatly improved the toxicity of carboplatin in vitro compared to free carboplatin, whereas only a modest improvement and even a reduction of efficiency were measured with the anionic non-pegylated (L3) and the pegylated (L4) liposomes. Conversely, only the L4 liposome significantly increased the median survival time of Fisher rats implanted with the F98 tumor, compared to free carboplatin. Neurotoxicity assays performed with the empty L4′ liposome showed that the lipid components of L4 were not toxic. These results suggest that the positive charge on liposomes L1 and L2, which is known to promote binding to cell membrane, facilitates carboplatin accumulation in cancer cells explaining their higher efficacy in vitro. Conversely, negatively charged and pegylated liposome (L4) seems to diffuse over a larger distance in the tumor, and consequently significantly increased the median survival time of the animals. Conclusions: Selection of the best liposomal formulation based on in vitro studies or animal model can result in contradictory conclusions. The negatively charged and pegylated liposome (L4) which was the less efficient formulation in vitro showed the best therapeutic effect in animal model of GBM. These results support that relevant animal model of GBM must be considered to determine the optimal physicochemical properties of liposomal formulations.
Radiation stimulates the expression of inflammatory mediators known to increase cancer cell invas... more Radiation stimulates the expression of inflammatory mediators known to increase cancer cell invasion. Therefore, it is important to determine whether anti-inflammatory drugs can prevent this adverse effect of radiation. Since cyclooxygenase-2 (COX-2) is a central player in the inflammatory response, we performed studies to determine whether the COX-2 inhibitor NS-398 can reduce the radiation enhancement of cancer cell invasion. Thighs of Balb/c mice treated with NS-398 were irradiated with either daily fractions of 7.5 Gy for five consecutive days or a single 30 Gy dose prior to subcutaneous injection of nonirradiated MC7-L1 mammary cancer cells. Five weeks later, tumor invasion, blood vessel permeability and interstitial volumes were assessed using magnetic resonance imaging (MRI). Matrix metalloproteinase-2 (MMP-2) was measured in tissues by zymography at 21 days postirradiation. Cancer cell invasion in the mouse thighs was increased by 12-fold after fractionated irradiations (5 ×...
Irradiation of brain stimulates the expression of inflammatory mediators, some of which can modif... more Irradiation of brain stimulates the expression of inflammatory mediators, some of which can modify the ability of cancer cells to infiltrate the brain. In the present study, the time window during which this stimulation occurs was determined. Brain of Fischer rat was irradiated (15 Gy) and expression of pro-inflammatory mediators IL-1β, IL-6 and TNF-α was measured from 4 h to 20 days post-irradiation. Level of the matrix metalloproteinase 2 (MMP-2) and prostaglandin E2 (PGE2) which can favor cancer cell infiltration were also measured. The F98 glioma cells were implanted either during (4 h post-irradiation) or after (10 days post-irradiation) the pro-inflammatory phase. Infiltration distance of F98 cells in brain parenchyma and the median survival time of the animals were determined. Expression of IL-1β, IL-6 and TNF-α was significantly increased in the irradiated brains with a peak at 4 h post-irradiation. Implantation of F98 glioma cells 4 h post-irradiation reduced the median survival time of Fischer rats to 18 days, compared to 25 days when the F98 were implanted in non-irradiated brain. Irradiation of the brain increased the distance of infiltration of F98 cells and was associated with increased levels of MMP-2 and PGE2. Conversely, F98 cells implanted 10 days post-irradiation have infiltrated the brain over a shorter distance and the median survival time of rats was increased to 35 days. Cancer recurrence is frequently observed in GBM patients. A better understanding of the inflammatory response observed in irradiated brain could contribute to develop new therapeutic modalities to further increase the efficiency of radiotherapy.
Targeted and whole-brain irradiation in humans can result in significant side effects causing dec... more Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The purpose of this work is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. Methods: Euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomography (CT), to estimate positioning variations relative to the bregma skull reference point. Using a rat brain atlas and the stereotactic bregma coordinates obtained from CT images, different regions of the brain were delimited and a treatment plan was generated. A single isocenter treatment plan delivering ≥100 Gy in 100% of the target volume was produced by Leksell GammaPlan using the 4 mm diameter collimator of sectors 4, 5, 7, and 8 of the Gamma Knife unit. Impact of positioning deviations of the rat brain on dose deposition was simulated by GammaPlan and validated with dosimetric measurements. Results: The authors' results showed that 90% of the target volume received 100 ± 8 Gy and the maximum of deposited dose was 125 ± 0.7 Gy, which corresponds to an excellent relative standard deviation of 0.6%. This dose deposition calculated with GammaPlan was validated with dosimetric films resulting in a dose-profile agreement within 5%, both in X-and Z-axes. Conclusions: The authors' results demonstrate the feasibility of standardizing the irradiation procedure of a small volume in the rat brain using a Gamma Knife.
Treatment of glioblastoma with platinum compounds modestly improves progression-free survival and... more Treatment of glioblastoma with platinum compounds modestly improves progression-free survival and may cause toxic effects which prevent use at higher dose that would otherwise improve the antineoplastic effect. To reduce toxicity, we propose to encapsulate the platinum drug in a liposome. We have also tested three methods of drug administration (intra-venous, intra-arterial and intra-arterial combined with blood brain barrier disruption) to determine which one optimizes the tumor cell uptake, limits the toxicity and delivers the best concomitance effect with radiotherapy. Cisplatin, oxaliplatin, their respective liposomal formulations, Lipoplatin TM and Lipoxal TM , and carboplatin were assessed in F98 glioma, orthotopically implanted in Fischer rats. We found that the modest accumulation of drugs in tumor cells after intravenous injection was significantly improved when the intra-arterial route was used and further increased after the transient opening of the blood brain barrier with mannitol. The liposomal formulations have largely reduced the toxicity and have allowed a better exploitation of the anticancer activity of platinum agent. Although the liposomes Lipoplatin TM and Lipoxal TM have shown a similar ability to that of carboplatin, to accumulate in brain tumors, the highest additive effect with radiotherapy was obtained with carboplatin. We conclude that the intra-arterial infusion of carboplatin or Lipoxal TM in concomitance with radiation therapy leads to the best tumor control as measured by an increase of mean survival time in Fischer rats implanted with the F98 glioma with a benefit in survival time of 13.4 and 6.5 days respectively compared to intravenous .
Despite significant advances, the radiotherapy and chemotherapy protocols marginally improve the ... more Despite significant advances, the radiotherapy and chemotherapy protocols marginally improve the overall survival of patients with glioblastoma. Lipoplatin ™ , and Lipoxal ™ , the liposomal formulations of cisplatin and oxaliplatin respectively, were tested on the F98 glioma cells for their ability to improve the cell uptake and increase the synergic effect when combined with ionizing radiation. The cytotoxicity and synergic effect of platinum compounds were assessed by colony formation assay, while the cellular uptake was measured by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). After 4 h exposure with platinum compounds, cells were irradiated (1.5 to 6.6 Gy) with a 60 Co source. The liposomal formulations were compared to their liposome-free analogs and to carboplatin. The concomitant treatment of F98 cells with carboplatin and radiation produced the highest radiosensitizing effect (30-fold increase). Among the platinum compounds tested, Lipoplatin ™ produced the most promising results. This liposomal formulation of cisplatin improved the cell uptake by 3-fold, and its radiosensitizing potential was enhanced by 14-fold. Although Lipoxal ™ can potentially reduce the adverse effect of oxaliplatin, a synergic effect with radiation was measured only when incubated at a concentration higher than its IC50. Conversely, concomitant treatment with cisplatin did not result in a synergic effect, as in fact a radioprotective effect was measured on the F98 cells. In conclusion, among the five platinum compounds tested, carboplatin and Lipoplatin ™ showed the best radiosensitizing effect. Lipoplatin ™ seems the most promising since it led to the best cellular incorporation and has already been reported to be less neurotoxic than other platinum compounds.
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Papers by Gabriel Charest