Preliminary assessment of photoactivated antimicrobial collagen on bioburden in a murine pressure ulcer model.

OBJECTIVE AND BACKGROUND DATA: Overcoming bacterial antibiotic resistance requires alternative strategies. The ability of photoactivated collagen-embedded flavins (PCF) to reduce bioburden in infected pressure ulcers was investigated. DESIGN AND METHODS: Two pressure ulcers were created on the dorsum of female BALB/C mice (n=40, 35 g) maintaining a 5 mm skin bridge between lesions. Ulcers and surrounding skin were covered with Tegaderm™ and inoculated with 0.1 mL of 1 × 10(5) colony-forming units (CFU)/mL methicillin-resistant Staphylococcus aureus (MRSA). Fluid was permitted to reabsorb for 10 min. In experiment 1, one wound from each animal was treated using PCF and photoradiation (PCF+R, n=12) or photoradiation alone (R, n=11). Composite dressing-treated wounds received 1 × 1 cm PCF discs. Overlying Tegaderm was excised, and PCF was placed over the wound and again covered with Tegaderm. Wounds were irradiated at 455 ± 5 nm (350 mW, 1 cm spot diameter, 15 min) using a diode laser 10 min after placement. Controls received no PCF or photoradiation (C, n=12). Animals were euthanized 24 h post-therapy. Quantitative bacterial counts (CFU/g tissue) were determined. In experiment 2, composite dressing-treated wounds were irradiated at 455 ± 5 nm (350 mW, 1 cm spot diameter, 15 min) using a diode laser 10 min after daily PCF placement (0, 1, 2, or 3 treatments, n=8/group). Controls received no treatment. Wounds were cultured daily. Animals were euthanized on day 7 post-infection. Quantitative bacterial counts were determined. RESULTS: PCF+R significantly reduced bacterial counts at 24 h (experiment 1, p<0.0001; experiment 2, p<0.05). The bacterial counts in rats receiving photoradiation alone were no different from those of untreated controls (experiment 1, p=0.24). PCF+R produced a 2-3 log reduction in bacterial counts (experiment 2, p<0.001). Antibacterial effects increased with number of treatments, and persisted for several days post-therapy (p<0.002). CONCLUSIONS: PCF+R inhibited bacterial growth in this model. This effect increased with successive treatments, persisting several days post-therapy. Further studies to optimize this treatment modality are warranted.

Laparoscopic mesh fixation using laser-assisted tissue soldering in a porcine model.

BACKGROUND AND OBJECTIVE: Animal studies using open surgical models indicate that collagen solder is capable of fixation of surgical meshes without interfering with tissue integration, increasing adhesions, or increasing inflammation intraperitoneally. This study describes development of instrumentation and techniques for laparoscopic herniorrhaphy using laser-assisted soldering technology. STUDY DESIGN AND METHODS: Anesthetized 20 kg to 25 kg female Yorkshire pigs underwent laparoscopy with a 3-trocar technique. Parietex TET, Parietex TEC, and Prolene mesh segments (5 x 5 cm) were embedded in 55% collagen solder. Segments were inserted by using a specially designed introducer and affixed to the peritoneum by using prototype laser devices (1.45 micro, 4.5 W continuous wave, 5-mm spot, 55 degrees C set temperature) and a custom laparoscopic handpiece (IPOM). Parietex PCO mesh was inserted and affixed using the Endo-hernia stapler (Control). Animals were recovered and underwent second-look laparoscopy at 6 weeks. Mesh sites were harvested after animals were euthanized. RESULTS: The mesh-solder constructs were easily inserted and affixed in an IPOM approach. Prolene mesh tended to curl at its edges as the solder was melted. Postoperative healing was similar to that in Control segments in all cases. DISCUSSION AND CONCLUSION: Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce the use of staples or other foreign bodies for laparoscopic mesh fixation, prevent tissue ischemia and possibly nerve entrapment, which result in severe postoperative pain and morbidity. Laser-assisted mesh fixation is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted.

Transabdominal preperitoneal herniorrhaphy using laser-assisted tissue soldering in a porcine model.

BACKGROUND AND OBJECTIVES: Collagen solder is capable of fixation of surgical meshes during laparoscopic herniorrhaphy without compromising tissue integration, increasing adhesions or inflammation. This pilot study describes development of instrumentation and techniques for transabdominal preperitoneal (TAPP) herniorrhaphy using laser-assisted soldering technology. METHODS: Anesthetized 20-kg to 25-kg female Yorkshire pigs underwent laparoscopy performed using a 3-trocar technique. Peritoneal incisions were made and pockets created in the preperitoneal space for mesh placement. Parietex TEC mesh segments embedded in 60% collagen-solder were soldered to the muscle surface by using a prototype laser (1.45micro, 4.5W CW, 5mm spot, and 55 degrees C set temperature) and custom laparoscopic handpiece. Parietex TEC mesh segments (Control) were affixed to the muscle with fibrin sealant (Tisseel). Peritoneal closure was with staples (Control) or by soldering collagen embedded Vicryl mesh segments over the peritoneal incision (Mesh/TAPP). Segments were inserted using a specially designed introducer. Animals were recovered and underwent second-look laparoscopy at 6 weeks postimplantation. Mesh sites were harvested after animals were euthanized. RESULTS: The mesh-solder constructs were easily inserted and affixed in the TAPP approach. Tisseel tended to drip during application, particularly in vertical and ventral locations. Postoperative healing was similar to Control segments in all cases. Mesh/TAPP closures healed without scarring or adhesion formation. DISCUSSION AND CONCLUSION: Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce use of staples for laparoscopic mesh fixation and peritoneal closure. Laser-assisted mesh fixation and peritoneal closure is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted.

Novel laser-activated solder for sealing corneal wounds.

PURPOSE: To compare the effectiveness of a laser-activated biological tissue solder with that of standard sutures for sealing corneal incisions. METHODS: Two keratome knives measuring either 3.0 mm or 2.85 mm were used to create a non-self-sealing peripheral oblique corneal wound (POCW) or a central perpendicular corneal wound (CPCW) in fresh rabbit cadaver eyes. Wounds were sealed with a solder strip (POCW; n = 5), a solder patch (CPCW; n = 5), or three interrupted nylon 10-0 sutures (n = 5). After the solder was placed on the wound, a diode laser was used to activate the solder, resulting in cross-linking to tissue. Wound stability was tested by a stepwise infusion of saline, and pressure changes were monitored with a digital manometer. Leaking pressure was recorded. RESULTS: The pressurized mean baseline IOP in the intact globe was 131.13 mm Hg (SD, 4.66). Mean IOP after CPCW was 1.7 mm Hg (SD, 0.13); for POCW it was 3.62 mm Hg (SD, 3.09). For the CPCW group, the mean leaking pressure in the sutured eyes was 82.76 mm Hg (SD, 6.55), whereas in the solder patch it was 101.42 mm Hg (SD, 29.92; P = 0.2222). For the POCW group, the mean leaking pressure in the sutured eyes was 33.44 mm Hg (SD, 9.38), and the mean IOP achieved in the solder repaired eyes was 125.16 mm Hg (SD, 9.85; P = 0.0079). CONCLUSIONS: The tested laser-activated solder was as effective as sutures when used as a patch and superior to sutures for clear corneal incisions in this animal ex vivo model.

Histologic assessment of mesh fixation following laser-assisted tissue soldering in a lapine model.

OBJECTIVE: Wound histology and mesh bioincorporation following intraperitoneal fixation using laser-assisted soldering was evaluated. METHODS: 2.8-3.2 kg NZW rabbits underwent laparotomy. Controls had 2x2 cm segments of Mersilene stapled to peritoneum. Group 2 segments were affixed with 55% collagen solder onlay by fiber-coupled diode laser (1.43 +/- 10 micro, 2.5 W CW, 4 mm spot, 60 degrees C set temperature). Group 4 had Mersilene inlaid into melted solder. Group 3 had solder-embedded Vicryl mesh affixed. Animals were euthanized at 0, 2, 4, 6 weeks. Fixed sections were assessed for integrity, inflammation, and fibrosis using H & E, Masson's Trichrome and Evans Van Gieson staining. RESULTS: Histology demonstrated cell types, local mesh reaction, and progressive evidence of solder reabsorption mimicking normal healing and bioincorporation. Mersilene groups demonstrated normal arrangement of collagen-rich layers around mesh. CONCLUSION: Collagen-based tissue soldering permits normal wound healing and may mitigate use of staples. Further development of this strategy is warranted.