Cathepsin B-degradable, NIR-responsive nanoparticulate platform for target-specific cancer therapy.

Stimuli-responsive anticancer formulations can promote drug release and activation within the target tumour, facilitate cellular uptake, as well as improve the therapeutic efficacy of drugs and reduce off-target effects. In the present work, indocyanine green (ICG)-containing polyglutamate (PGA) nanoparticles were developed and characterized. Digestion of nanoparticles with cathepsin B, a matrix metalloproteinase overexpressed in the microenvironment of advanced tumours, decreased particle size and increased ICG cellular uptake. Incorporation of ICG in PGA nanoparticles provided the NIR-absorbing agent with time-dependent altered optical properties in the presence of cathepsin B. Having minimal dark toxicity, the formulation exhibited significant cytotoxicity upon NIR exposure. Combined use of the formulation with saporin, a ribosome-inactivating protein, resulted in synergistically enhanced cytotoxicity attributed to the photo-induced release of saporin from endo/lysosomes. The results suggest that this therapeutic approach can offer significant therapeutic benefit in the treatment of superficial malignancies, such as head and neck tumours.

New methods for innovation: the development of a toolbox for natural orifice translumenal endoscopic surgery (NOTES) procedures.

BACKGROUND: Devices used for flexible intralumenal procedures are inadequate when used for intraperitoneal surgical procedures such as cholecystectomy. OBJECTIVE: To assess/address limitations of flexible endoscopic devices in intraperitoneal surgery. DESIGN: To describe processes used to invent new devices to facilitate this new surgical genre. SETTING: Engineering laboratory. PATIENTS: None. INTERVENTIONS AND INVENTIONS: Reviews of the limitations of flexible endoscopic instruments and instrumentation/invention needs for a "NOTES cholecystectomy" were completed. MAIN OUTCOME MEASURES: The appropriateness of existing methods of device innovation was evaluated against an inventory of new technologies necessary to perform NOTES. The deficiencies in traditional innovation methods led to the creation of a novel process for invention of new medical devices: the "Inventorama." METHODS: Cooperation between clinicians and industry to develop device concepts to enable NOTES. RESULTS: The devices included: (1) steerable flex trocar, (2) rotary access needle, (3) bipolar hemostasis forceps, (4) Maryland dissectors, (5) articulating hook knife, (6) rotating hook knife, (7) articulating graspers, (8) scissors, (9) ligating clip applier, and (10) tissue apposition system. Six of these ten were built and tested as initial crude prototypes in the Inventorama process; two underwent major modifications. Three were invented via alternate methods, including by independent clinicians. CONCLUSIONS: A new method for efficient medical device invention and development was created to address key technology needs for NOTES. The result was a "toolbox" of devices designed to address the key surgical activities necessary for advanced intralumenal and translumenal flexible endoscopic procedures.

Optimal conditions for successful ablation of high-grade dysplasia in Barrett's oesophagus using aminolaevulinic acid photodynamic therapy.

Photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA-PDT) is an attractive alternative to PDT with porfimer sodium for the treatment of high-grade dysplasia (HGD) in Barrett's oesophagus (BO) because of the shorter duration of light photosensitivity and low risk of oesophageal stricture formation. Published results, however, show marked variation in its efficacy, and optimum treatment parameters have not been defined. This study investigated how the dose of ALA and the colour of the illuminating light influenced the biological effect. Twenty-seven patients were enrolled into a randomised controlled trial of red versus green (635 nm or 512 nm) laser light activation for the eradication of HGD with ALA-PDT in Barrett's oesophagus. A further 21 patients were subsequently treated with the most effective regimen. Regular endoscopic follow-up with quadrantic biopsies every 2 cm was performed. The primary outcome measure was eradication of HGD. Patient's receiving ALA at 30 mg/kg relapsed to HGD more than those receiving 60 mg/kg (P = 0.03). Additionally, for those treated with ALA 60 mg/kg, red laser light was more effective than green laser light (P = 0.008). Kaplan-Meier analysis of the 21 patients who were subsequently treated with this optimal regimen demonstrated an eradication rate of 89% for HGD and a cancer-free proportion of 96% at 36 months' follow-up. Using an ALA dose of 60 mg/kg activated by 1,000 J/cm red laser light, we found that ALA-PDT was a highly effective treatment for high-grade dysplasia in Barrett's oesophagus.

Light penetration in the human prostate: a whole prostate clinical study at 763 nm.

Photodynamic therapy (PDT) is being investigated as a treatment for localized prostate cancer. Photodynamic therapy uses a photosensitizing drug which is activated by a specific wavelength of light, in the presence of oxygen. The activated drug reacts with tissue oxygen to produce reactive oxygen species which are responsible for localized tissue necrosis. One of the determinants of the PDT effect is the penetration of light in the prostate. This study assesses the penetration depth of 763 nm light throughout the prostate. Eight men undergoing multiple hollow needle insertion for high dose rate brachytherapy were recruited. 763 nm light, produced by a diode laser, was delivered to the prostate using cylindrically diffusing optical fibers within the plastic needles. Light was detected at different distances from the source, using an isotropic detector within nearby needles. Penetration depth was calculated using the Boltzmann approximation to the diffusion equation. Delivery detector fiber separation was measured on computed tomography. The mean penetration depth was 0.57 cm, but there was within patient variation of a mean factor of 4.3. Further work is ongoing to assess the effect of such variability in light penetration, on the PDT effect.

How light dosimetry influences the efficacy of photodynamic therapy with 5-aminolaevulinic acid for ablation of high-grade dysplasia in Barrett's esophagus.

Photodynamic therapy (PDT) with 5-aminolaevulinic acid (ALA) is a novel treatment for high-grade dysplasia (HGD) in Barrett's esophagus (BE). Our aim was to evaluate the effectiveness of differing light doses. Patients with HGD in BE received oral ALA (60 mg/kg) activated by low (500 J/cm), medium (750 J/cm), high (1,000 J/cm), or highest (1,000 J/cm x2) light dose at 635 nm. Follow-up was by regular endoscopy with quadrantic biopsies. Twenty-four patients were treated. Successful eradication of HGD was significantly correlated with light dose (log rank, p < 0.01). Six of eight patients (75%) treated with the highest light dose, one of two treated with high dose (50%), two of nine (22%) receiving medium light dose, and zero of five receiving low light dose had successful eradication of HGD (median follow-up 45 months, range 1-78 months). No skin photosensitivity or esophageal strictures occurred. The efficacy of ALA-PDT for eradication of HGD in BE is closely related to the light dose used. With a drug dose of 60 mg/kg and light at 635 nm, we recommend a minimum light dose of 1,000 J/cm of esophagus. This dose appears safe.

Endoscopic transgastric lymphadenectomy by using EUS for selection and guidance.

BACKGROUND: EUS-guided fine needle aspiration (EUS-FNA) is a reliable tool for tissue diagnosis of unexplained mediastinal or perigastric lymphadenopathy but may be ineffective in sampling a small malignant focus in it or removing an entire node. OBJECTIVE: To develop a new EUS-guided endoscopic-transgastric method to approach (sentinel) lymph nodes, including node marking and lymphadenectomy. DESIGN: Experimental study. SETTING: Animal experiments at an approved university college. SUBJECTS: Six pigs had a linear-array EUS examination 1 week after a transgastric procedure. All had reactive perigastric lymph nodes. INTERVENTIONS: Selected nodes were punctured with a 19-gauge EUS needle. A metal anchor with thread, loaded onto the needle, was placed across the lymph nodes to pull the node toward the stomach. After gastric-wall dissection with a needle knife at the point of emergence of the thread, the nodes were removed by pulling on the thread and the anchor. The gastric incision was closed with an endoscopic suturing system. MAIN OUTCOME AND MEASUREMENTS: Proof of the feasibility to endoscopically remove paragastric lymph nodes by an EUS-guided transgastric approach. RESULTS: In all pigs, lymph-node marking with an anchor and thread was possible. Traction exerted on these nodes showed that they could be pulled against the gastric wall for subsequent removal. In 2 of 6 examinations, the entire sequence of the procedure, node tagging, gastric-wall incision, lymphadenectomy, and wall closure was performed. No serious complication occurred. LIMITATIONS: Animal study throughout, small numbers, no humans to date. CONCLUSIONS: Transgastric lymphadenectomy with EUS for node selection and capturing seems feasible.

Colon cleaning during colonoscopy: a new mechanical cleaning device tested in a porcine model.

BACKGROUND: Poor colon cleaning frequently impairs colonoscopy. The aim of the study was to develop a method of cleaning the colon during colonoscopy. METHODS: A soft-tipped catheter with a water jet spray at its tip was designed to break up and propel stool contents in the direction of the anus. Stool contents were collected in a container attached to an endoscopy trolley. OBSERVATIONS: In bench tests, colon models filled with porridge were rapidly cleaned. Unprepared colons (n = 15) of anesthetized pigs were cleared in a few minutes by using this device at colonoscopy, by advancing the catheter under direct vision into concretions, which were rapidly broken down. There was minimal trauma to mucosa in these survival studies. CONCLUSIONS: A colon cleaning method for use at colonoscopy was highly effective in cleaning colon models and in unprepared pig colon. This device may have a role in cleaning the colon in unprepared or poorly prepared patients.

The Cath-Cam: a new concept in colonoscopy.

BACKGROUND: Guidewires and catheters exert less force on the gut wall than an endoscope. OBJECTIVE: To develop a guidewire-assisted device for colonoscopy. METHODS: A light-weight flexible catheter illuminated with light-emitting diodes was designed to carry an ultraslim high-resolution videoendoscope of 3 mm. Tip bend stiffness was 5 times less than a colonoscope. Hinged guidewires were passed, folded, through the accessory channel. A loop could be rapidly formed to explore the lumen. RESULTS: The catheter followed curves of excised pig colon and exerted significantly less force on the colon wall than a colonoscope (mean 1.6 +/- 0.23 N vs 3.0 +/- 0.37 N, P < .05; bend-radius, 80 mm). Survival studies in pigs showed that the guidewire loop could be advanced under visual control and the Cath-Cam could be advanced by using much less force than the colonoscope. CONCLUSIONS: A catheter-based colonoscope with a miniature video imager reduced the force required for successful colonoscopy in pigs.

Endoscopic full-thickness resection: circumferential cutting method.

BACKGROUND: Endoscopic full-thickness resection (EFTR) at flexible endoscopy might allow less-invasive removal of more deeply penetrating cancers that have not spread to the serosal surface and more complete histologic examination of the excised tissue. OBJECTIVE: A method for closure of full-thickness defects in the stomach wall would be valuable for other endosurgical applications. SETTING: A method that uses an end cap and band-ligation without prior injection of saline solution to perform EFTR gave good results and was safe in pig studies. There is a size limitation of cancers that can be resected en bloc when using this method. The depth of resection was also variable. DESIGN AND INTERVENTIONS: EFTR was achieved by circumferential cutting with a sphincterotome and a snare. A prototype bidirectional cutter was tested. Sutured closure was accomplished by using a sheathed needle, a metal tag, and a thread at the tip, passed through a 2.8-mm accessory channel. Knot-tying devices secured the sutured defect. MAIN OUTCOME MEASUREMENTS: EFTR was studied in non-survival (n = 4) and survival (n = 8) experiments in pigs. RESULTS: Full-thickness specimens were resected from the gastric wall (100%, 12/12), and the defects were closed by using sewing and knot-tying devices (100%, 12/12). LIMITATIONS: A healing ulcer at the suturing site was evident at follow-up endoscopy in the survival experiments. Bleeding, which was stopped by suturing, occurred in 1 pig (8.3%, 1/12). All pigs survived these experiments without complications (100%, 8/8). CONCLUSIONS: Circumferential EFTR was feasible and appeared safe in survival experiments. This method might allow larger and deeper resection of tumors in the gastric wall.

Endoscopic full-thickness resection with sutured closure in a porcine model.

BACKGROUND: Some early gastric cancers might be advantageously staged and treated by full-thickness resection if secure methods for closing the defect were available. The aim of this study was to test the feasibility of full-thickness gastric resection. METHODS: Full-thickness gastric resections were performed by using a ligating device without submucosal injection in survival studies in pigs (n = 8). The defects were closed by using new methods for suturing, locking, and cutting thread through a 2.8-mm accessory channel. Stitches (n = 2-4) were placed close to the target area before resection. OBSERVATIONS: Full-thickness resections (n = 8) were performed. The pigs survived without incident for 21 to 28 days. Healing of the suture site was evident at follow-up endoscopy. Suture sites were water tight. The pull-out force with stitches by using this new sewing method was significantly higher than with endoscopic clips (20.3 N +/- 0.94 vs. 2.2 N +/- 0.42, p < 0.05). CONCLUSIONS: Endoscopic full-thickness resection with sutured defect closure was feasible and appeared safe in these survival experiments.

Photodynamic therapy with m-tetrahydroxyphenyl chlorin for high-grade dysplasia and early cancer in Barrett's columnar lined esophagus.

BACKGROUND: Many patients with high-grade dysplasia and localized adenocarcinoma in Barrett's esophagus have localized disease but are either unfit for major surgery or decline esophagectomy. Photodynamic therapy with the powerful photosensitizer m-tetrahydroxyphenyl chlorin may be a nonsurgical therapeutic option. METHODS: This is a pilot study to evaluate the efficacy and complications of m-tetrahydroxyphenyl chlorin photodynamic therapy. The design is a case series of 19 consecutive patients at a tertiary referral unit with a special interest in photodynamic therapy. The study included 7 patients with high-grade dysplasia and 12 with early esophageal cancer, who had refused or were unfit for esophagectomy. Three days after photosensitization with 0.15 mg/kg m-tetrahydroxyphenyl chlorin, red or green light was delivered endoscopically when using either a bare fiber or a diffuser device. Results were assessed by endoscopic surveillance. RESULTS: By using red light via the diffuser, 4/6 patients with cancer and 3/4 with high-grade dysplasia were successfully treated with photodynamic therapy alone. When using the bare-tipped fiber, there was one procedure-related death and only 1/5 patients with cancers were successfully treated. Two others were downgraded to high-grade dysplasia. With green light delivered via a diffuser, 0/3 patients with high-grade dysplasia are in long-term remission. Two serious complications arose (including one death) from taking multiple biopsy specimens too soon after therapy. Two esophageal strictures occurred. CONCLUSIONS: Photodynamic therapy with m-tetrahydroxyphenyl chlorin is, potentially, a valuable therapeutic option for localized esophageal neoplasia. Red light via a diffuser device appears to be the most effective light-delivery technique. Biopsy specimens should not be taken for at least 2 months after treatment.

Transgastric gastropexy and hiatal hernia repair for GERD under EUS control: a porcine model.

BACKGROUND: Endoluminal operations for gastroesophageal reflux currently are limited by the inability to visualize and manipulate structures outside the wall of the gut. This may be possible by using EUS. The aims of this study were the following: to define the EUS anatomy of structures outside the gut that influence reflux, to place stitches in the median arcuate ligament, to perform posterior gastropexy, and to test the feasibility of crural repair under EUS control in pigs. METHODS: In survival experiments in 22 pigs, by using a linear-array echoendoscope, the median arcuate ligament and part of the right crus were identified and punctured with a needle, which served as a carrier for a tag and thread. These were anchored into the muscle. An endoscopic sewing device was used, allowing stitches to be placed through a 2.8-mm accessory channel to any predetermined depth. New methods allowed knot tying and thread cutting through the 2.8-mm channel of the echoendoscope. RESULTS: Stitches were placed through the gastric wall into the median arcuate ligament, and one stitch was placed just beyond the wall of the lower esophageal sphincter. The stitches were tied together and locked against the gastric wall. Median lower esophageal sphincter pressure, determined manometrically, was 11 mm Hg before surgery and 21 mm Hg after stitch placement (p=0.0002). The length of the lower esophageal sphincter increased from a median of 2.8 cm before the procedure to 3.5 cm after the procedure. At the postmortem, the median force required to pull the tags out of the median arcuate ligament was 2.8 kg. CONCLUSIONS: This study demonstrates that transgastric gastroesophageal reflux surgery, by using stitching under EUS control, can significantly increase lower esophageal sphincter pressure in pigs.

Transluminal endosurgery: single lumen access anastomotic device for flexible endoscopy.

BACKGROUND: Forming anastomoses between two hollow organs at flexible endoscopy might reduce the need for surgery for obstructing malignancy. Current methods require access to both lumens. The aim of this work was to develop methods of forming an anastomosis at flexible endoscopy, such as a gastrojejunostomy or cholecystoduodenostomy, when access to only one lumen is feasible. METHODS: A modified needle was passed through a large-channel echoendoscope from the accessible lumen into the target hollow organ. An anastomotic device was formed by using two 7F catheter segments, which were pushed over a guidewire into the target, the less accessible lumen. When released, by withdrawing the guidewire, the catheters formed a cross shape and created an anastomosis when compressed against a plate from the accessible side. OBSERVATIONS: These devices were tested in live animal experiments. With an echoendoscope in the stomach, it was repeatedly possible to place needles, threaded tags, and guidewires into the small intestine and gallbladder. In 4 to 7 days, anastomoses were formed in 16 pigs between the small intestine and the stomach, and between the gallbladder and the stomach. The initial diameter of the anastomoses ranged from 3 to 9 mm. No complication occurred. CONCLUSIONS: It is feasible to form anastomoses at flexible endoscopy when access is limited to a single side.

A through-the-scope device for suturing and tissue approximation under EUS control.

BACKGROUND: The ability to place sutures under EUS control might allow development of a new type of transluminal endosurgery. The aim of this study was to develop endoscopic methods for suturing to variable predetermined depths in the wall of the GI tract and to allow fixation of adjacent hollow organs under EUS control. METHODS: A suturing device was constructed for suturing under EUS control to any desired depth. Sutures can also be placed into hollow or solid organs within 5 cm of the endoscope tip. The device allows multiple sutures to be placed without withdrawing the endoscope. Stitching, knot-tying, and thread-cutting are achieved through a 2.8-mm accessory channel. RESULTS: Multiple (>100) sutures were placed in predetermined gut wall layers in pigs. Sutures were placed in the gallbladder (n = 7) and small intestine (n = 8) to fix the gallbladder/small intestine to the stomach and allow traction for the insertion of stents and other devices through the 2 lumens. CONCLUSION: A new method for stitching under flexible EUS control is described. This technology was used to place sutures at precise depths in the GI tract. It allowed fixation of other organs to the accessible GI tract for various purposes including delivery of stents and devices for creating anastomoses.