The first sutureless, laser-welded, end-to-end bowel anastomosis

Mesenchymal Stem Cells Combined with Tissue Fusion Technology Promoted Wound Healing in Porcine Bowel Anastomosis

Objective

To evaluate the possible biological effect of allogenic mesenchymal stem cells (MSCs) combined with tissue fusion technology on the anastomosis.

Methods

Sixteen pigs were divided into a 7 d group and 14 d group, each of which was further subdivided into an MSC-treated group and a control group. Five anastomoses per animal were established using LigaSure ForceTriad (Covidien, MA, USA), a tissue sealing system. Cell migration and tissue-specific differentiation potency, in addition to potential cytokine and genetic changes, were investigated.

Results

There were no significant between-group differences in postoperative complications and anastomosis burst pressure. The number of proliferating cell nuclear antigen- (PCNA-) positive cells was significantly higher in the MSC-treated group as compared with that in the control group (P = 0.021). Labeled MSCs were found in the mucosal layer, villus, and lamina propria, as well as in the lamina muscularis mucosae, where they exhibited characteristics of smooth muscle cells.

Conclusions

Grafted MSCs significantly promoted epithelial and connective cell proliferation and maintained their cell migration capacity and differentiation potential in the fused anastomotic tissues, without causing severe postoperative complications.

Exogenous bFGF or TGFβ1 accelerates healing of reconstructed dura by CO2 laser soldering in minipigs

This study aims to explore the probable mechanism of better result of dural reconstruction by CO2 laser soldering and the effect of exogenous basic fibroblast growth factor (bFGF) or transforming growth factor-beta1(TGFβ1) on wound healing. In part I of the study, ten minipigs were randomized into two equal groups, and the dural defects were reconstructed by conventional fibrin glue (FG) bonding (group I a) or by CO2 laser soldering (group Ib). In part II, 36 minipigs were randomized into three equal groups, and the dural defect was reconstructed by CO2 laser soldering; then exogenous bFGF or TGFβ1 was administered in group IIb and group IIc, respectively, while group IIa served as control group. The dural specimens were harvested at 1st week postoperatively in part I; and at 1st, 2nd, 3rd, and 4th week postoperatively in part II, they were examined for healing condition and subjected to hematoxylin-eosin (HE) staining and immunohistochemical (IHC) staining with antibodies against bFGF and TGFβ1. In part I, group Ib showed higher fibroblast cell density than group Ia (P < 0.05). The optical density (OD) for IHC staining with antibodies against bFGF of group Ib was significantly higher than that of group Ia (P < 0.05), and for IHC staining with antibodies against TGFβ1, group Ib showed positive staining while group Ia was negative. In part II, administering exogenous bFGF or TGFβ1 made a left shift of fibroblast cell number-time curve compared with control group. For specimens' IHC staining with antibodies against bFGF, the OD of group IIb was higher than that of group IIa in the corresponding time. For specimens' IHC staining with antibodies against TGFβ1, the OD of groups IIb and IIc was both higher than that of group IIa (P < 0.05 and P < 0.01, respectively). In conclusion, CO2 laser may trigger fibroblast proliferation through stimulating the secretion of bFGF and TGFβ1. Topically administering exogenous bFGF or TGFβ1 could accelerate the healing of the reconstructed dura by enhancing secretion of bFGF and/or TGFβ1 and promoting the process of fibroblast gathering-degrading.

Radiofrequency-induced small bowel thermofusion: an ex vivo study of intestinal seal adequacy using mechanical and imaging modalities

BACKGROUND

Bipolar radiofrequency (RF) induced tissue fusion is believed to have the potential to seal and anastomose intestinal tissue thereby providing an alternative to current techniques which are associated with technical and functional complications. This study examines the mechanical and cellular effects of RF energy and varying compressive pressures when applied to create ex vivo intestinal seals.

METHODS

A total of 299 mucosa-to-mucosa fusions were formed on ex vivo porcine small bowel segments using a prototype bipolar RF device powered by a closed-loop, feedback-controlled RF generator. Compressive pressures were increased at 0.05 MPa intervals from 0.00 to 0.49 MPa and RF energy was applied for a set time period to achieve bowel tissue fusion. Seal strength was subsequently assessed using burst pressure and tensile strength testing, whilst morphological changes were determined through light microscopy. To further identify the subcellular tissue changes that occur as a result of RF energy application, the collagen matrix in the fused area of a single bowel segment sealed at an optimal pressure was examined using transmission electron microscopy (TEM).

RESULTS

An optimal applied compressive pressure range was observed between 0.10 and 0.25 MPa. Light microscopy demonstrated a step change between fused and unfused tissues but was ineffective in distinguishing between pressure levels once tissues were sealed. Non uniform collagen damage was observed in the sealed tissue area using TEM, with some areas showing complete collagen denaturation and others showing none, despite the seal being complete. This finding has not been described previously in RF-fused tissue and may have implications for in vivo healing.

CONCLUSIONS

This study shows that both bipolar RF energy and optimal compressive pressures are needed to create strong intestinal seals. This finding suggests that RF fusion technology can be effectively applied for bowel sealing and may lead to the development of novel anastomosis tools.

Intraluminal albumin stent assisted laser welding for ureteral anastomosis

BACKGROUND AND OBJECTIVES

The success of laser tissue welding or soldering depends on optimal laser settings, solder material, and tissue type and geometry. To develop a practical laser welding technique for ureteral repair, an intraluminal albumin stent was designed to enhance the welding effects on ureteral end to end anastomosis.

STUDY DESIGN/MATERIALS AND METHODS

In vitro porcine ureters were anastomosed using an albumin stent alone, the albumin stent plus a solder, and the solder alone. All welding was performed with an 810-nm diode laser with either a continuous wave (1 W, CW) or two pulse modes (2 W, 3.3 Hz; 1 W, 5 Hz). Laser parameters, tensile strength (TS) and burst pressure (BP) of the ureteral anastomosis, and tissue thermal injury were measured.

RESULTS

In the 2-W pulse mode, BP in the albumin stent plus solder group (mean 185 mmHg) and the stent only group (mean 133 mmHg) were significantly higher than the solder only group (mean 77 mmHg, P < 0.05). Laser ureteral anastomosis with the stent plus solder group at 1-W CW and 2-W pulse laser modes yielded the highest TS (mean 97, 82 g) and BP (mean 183, 185 mmHg). Among the three modes, the 1 W pulse delivered the lowest energy and yielded the lowest TS and BP in ureteral anastomosis. There was no significant difference in the thermal damage to the tissue among the modes and groups.

CONCLUSIONS

Using the albumin stent increased the reliability of ureter end-to-end laser anastomosis. Further studies will be warranted in vivo and other tubular organs as well.

Experimental oesophagogastric anastomosis: preliminary report of a new compression device that also fragments

Fifteen Beagle dogs underwent oesophagogastric anastomosis with a new device which enables a 'sutureless' compression anastomosis. The device fragmented and was passed in bits anally without causing obstruction. Immediate bursting pressure, tested in five dogs, was between 175 and 190 mmHg. The anastomoses of the remaining dogs were examined macroscopically and microscopically from day 6 to day 30. Healing was excellent with good muscular apposition and minimal residual inflammation.

First experimental sutureless laser anastomosis of the large bowel: long-term study

Large bowel anastomoses were successfully performed without sutures on New Zealand white rabbits using 1,064 nm, 0.4-W power pulsating Nd:YAG laser to create tissue welding.

PURPOSE

The aim of this study was to assess long-term results of our experimental data and summarize our experimental work on laser colon anastomosis.

METHODS

This experimental study investigated long-term integrity, degree of narrowing, animal body weight change, visual findings, microscopic appearance, and collagen concentration of laser colon anastomoses, compared with those of conventional sutured anastomoses at thirty and ninety postoperative days.

RESULTS

Two animals in the laser group died without leakage. Postsurgical course in all remaining rabbits studied was uneventful. Bursting pressures in the two groups were equivalent, but the laser group exhibited a consistent narrowing tendency. However, laser anastomoses demonstrated fewer and milder adhesions, and animals showed a better recovery of body weight. Histologically, laser anastomoses showed better layer-to-layer reconstitution without foreign body response and with less fibrosis. Difference in collagen (hydroxyproline) concentration did not reach statistical significance.

CONCLUSION

The nature of tissue welding via laser remains undefined, but there is definitely a future for laser bowel anastomosis.

Controlled temperature tissue fusion: argon laser welding of canine intestine in vitro

BACKGROUND AND OBJECTIVE

Thermal denaturation of proteins is recognized as a rate process governed by the local temperature-time response and is believed to be the principal mechanism for photothermal tissue welding. Since rate processes are exponential with temperature, feedback control of tissue surface temperature is hypothesized to create a quasi-constant rate of denaturation that will enhance the tissue welding process.

STUDY DESIGN, MATERIALS AND METHODS

Controlled temperature tissue welding of severed edges of fresh canine jejunum was performed in vitro by remote sensing of tissue surface temperature with an infrared sensor. A hardware controlled temperature feedback system opened and closed a shutter located in the beam path of an argon ion laser to provide constant temperature welding.

RESULTS

Strong tissue fusion was not possible at or below a surface temperature of 70 degrees C, but was accomplished at 80 degrees, 90 degrees, and 95 degrees, and 100 degrees C. Fusion was achieved with thermal coagulation of the collagenous submucosa and mucosal tissues. The bursting strength of welds created at 90 degrees C and 95 degrees C were significantly stronger than those performed at 80 degrees C.

CONCLUSION

Laser-assisted intestinal anastomoses created in vitro are optimally strong at 90-95 degrees C feedback control temperatures.

Prevention of pharyngocutaneous fistulas by means of laser-weld techniques

Although much has been written on methods of dealing with pharyngocutaneous fistulas once they have formed, there are few reports of methods of preventing fistula formation from occurring. We examined the use of laser-weld techniques with the neodymium:yttrium aluminum garnet (Nd:YAG) and diode lasers to seal pharyngotomy closures. Laser-weld techniques have been used successfully in many other tissues, but reports documenting use in the upper aerodigestive tract are minimal. Indocyanine-green dye-enhanced collagen and fibrinogen were studied as laser solder materials for the diode laser. Twenty-nine experimental animals were studied. Neither the Nd:YAG nor the diode laser was successful in preventing fistula formation. Tensiometric studies documented significant strength of the laser welds ex vivo, but this finding was not clinically significant.

Laser tissue welding: a comprehensive review of current and future clinical applications

Laser techniques for joining tissue, in combination with other surgical technologies, will be a hallmark of surgery in the next century. At present, there are many clinical applications of tissue welding and soldering which are beginning to achieve wide spread acceptance. These exciting clinical developments are the result of many advances which have been made in the past few years in our understanding of the mechanism of laser tissue welding. Also contributing to this progress are many important technical refinements such as tissue solders and feedback control of the laser device. In this article, we describe in depth the history and development of laser tissue welding including key theoretical concepts as well as crucial experiments which have added to our insight into this phenomenon. We also review the evolving concepts of its clinical application and indicate clinical applications which are likely to become more important in the future.

Experimental laser anastomosis of the colon. Long-term results and histologic findings after laser closure of colotomies

PURPOSE

Our previous experimental work showed the feasibility of colon anastomosis using laser; however, it also revealed a narrowing tendency after laser anastomosis. Long-term observation of the postoperative course of laser anastomosis was planned to assess this point.

METHODS

Clinical observation and histologic examination of transverse colotomies (average, 21.2 mm) in New Zealand white rabbits (n = 12) closed with a 1,064-nm neodymiumyttrium aluminum garnet (Nd:YAG) laser were carried out up to the third postoperative month, compared with closure of colotomies using a single layer of interrupted sutures of 5-0 Maxon (Davis & Geck, Pearl River, NY) in a control group (n = 12).

RESULTS

Whereas the narrowing tendency was observed up to one month after the operation in the laser group (P < 0.05), it disappeared at three months following the operation without causing abnormal weight loss during the experiment. Simultaneously, there was again a marked decrease in adhesion formation following laser anastomosis (P < 0.01). Collagen fibers were observed earlier in the laser group.

CONCLUSIONS

An earlier commencement of collagen synthesis after laser anastomosis was proved. A narrowing tendency, which was observed from seven days to one month postoperatively, disappeared at three months after laser anastomosis without exerting any effect on growth.

Development and initial application of a real time thermal control system for laser tissue welding

The ability to sense and control continuously surface temperatures of a tissue being exposed to laser radiation could standardize parameters and eliminate subjective interpretation of results during laser tissue repair. We describe the development and testing of a control system that enables the operator to maintain relatively specific tissue temperatures for the purpose of laser welding. After initial development, the infrared thermal control system combined with an argon laser was used to repair urethral defects in 45 adult male rats. Repairs were completed using various predetermined temperatures of 50, 60, 70, 80 or 90C. The integrity of each weld was quantitatively determined by measuring intraluminal bursting pressure immediately after repair. In all temperature groups bursting pressures were in excess of 85 mm. Hg. Those performed at 80C produced the strongest weld (analysis of variance p = 0.0001). However, welding temperatures above 70C sacrificed the integrity of the underlying urothelium producing obvious damage when viewed microscopically. We were able to demonstrate that temperature is an objective parameter of tissue welding that can be continuously assessed and controlled during the laser repair of tissue defects to produce effective, predictable welds.

Lasers in neurosurgery

Lasers have been used in neurosurgery for the past 25 years, undergoing modifications to suit the specific needs of this medical discipline. The present report reviews the current use of lasers in neurosurgical practice and examines the pros and cons of lasers in specific neurosurgical applications. In spite of their advantages, laser use is still not widespread in neurosurgery. One reason is the continued lack of complete control over real-time laser interactions with neural tissue. A greater acceptance and use of lasers by neurosurgeons will depend upon automated control over defined specific parameters for laser applications based upon the type of tissue, the desired effect on tissue, and application to the clinical situation without loss of precision and a lot of expense. This will require the integration of newer lasers, computers, robotics, stereotaxy, and concepts of minimally invasive surgery into the routine management of neurosurgical problems.

Chromophore enhanced laser welding of canine ureters in vitro using a human protein solder: a preliminary step for laparoscopic tissue welding

Laser welding of the genitourinary tract has the potential advantage of forming an immediate watertight seal. It may obviate the need for sutures, eliminate the inherent lithogenic reaction to suture, and potentially improve healing. In the current study we employed a KTP-532 laser in vitro to weld canine ureters. Ureters were transected over a stent and immediately repaired using the KTP-532 laser (power density 7.14 W/cm.2, spot size = 0.5 cm.) alone or in combination with different tissue solders. Solders consisted of 40% human albumin alone or with the addition of iron oxide or fluorescein as light absorbing dyes (chromophores). Following the repairs, intraluminal bursting strength and the total energy required to complete the repairs were measured. The KTP laser alone was not able to achieve a satisfactory repair. Successful ureteral repairs were achieved in all solder groups while maintaining ureteral continuity at supraphysiologic pressures.

Preparation of human albumin solder for laser tissue welding

Previous studies have demonstrated that the addition of a protein solder to augment the laser tissue weld significantly improves postoperative results. Herein we describe a method for the preparation of human albumin for use as a laser tissue solder. We also review the brief history of laser tissue solders and discuss recent advances using this technology.

First experimental sutureless end-to-end laser anastomosis of the large bowel. Short-term results

Completely sutureless end-to-end large bowel anastomoses were successfully created in New Zealand white rabbits (n = 26) by using a low-energy (0.4-W wave of power) Nd:YAG laser to produce welded anastomoses. In this study, the short-term integrity, degree of narrowing, macroscopic appearance, and microscopic findings were compared with those of the conventional interrupted one-layer anastomosis (n = 24) at zero, one, four, and seven days after surgery. Two rabbits in the laser group died from leakage. All remaining animals had an uneventful postoperative course. The bursting pressures in the laser group at zero, one, and four days were lower than those in the control group. The narrowing index of the laser anastomosis was higher than that of the suture anastomosis at four and seven days. However, the laser anastomoses showed fewer adhesions, no instances of bowel obstruction, and histologic healing with less fibrosis. The technique of laser anastomosis presents a promising alternative to suturing in reconstitution of the large bowel.

Endoscopic enhancement of the healing of high-risk colon anastomoses by low-power helium-neon laser. An experimental study

Recent studies suggest that helium-neon (He-Ne) lasers at low energy can enhance wound healing in intestinal anastomoses. In this experimental study, we tested the strength and collagen concentration of high-risk anastomoses of the rat colon after endoscopic irradiation by helium-neon laser. Our results show that repeated helium-neon laser irradiation (1.9 J/cm2) increases the bursting strength of the anastomoses by almost 100% on the fourth postoperative day. This effect is not observed by increasing the radiation dose (6.4 J/cm2). Differences in collagen (hydroxyproline) concentration did not reach statistical significance.

New technologies and future applications of surgical lasers. The right tool for the right job

The real future of surgical lasers, and indeed of surgery itself, will depend on the integration of the surgeon into a system incorporating real-time tissue sensors, computer-directed robotic manipulation, and laser-tissue interactions that are customized to the clinical task. The human surgeon will operate as the central judgmental element in this mechanized and semiautomated laser surgical system. Only then will we really be able to make use of the subtle and varied laser-tissue effects now being discovered.

First sutureless closure of a colotomy: short-term results of experimental laser anastomosis of the colon

To assess the possibility of laser anastomosis of the colon, experimental laser closure of colotomies was performed. Transverse colotomies (average 20.7 mm) in New Zealand white rabbits (n = 20) were closed with a 1,064-nm Nd:YAG laser at a pulsating 0.5-W wave of power, using guy sutures to approximate the tissue edges. The laser energy was applied through a specially designed hand piece and hand-held 600-microns gas-cooled noncontact quartz fiber to produce a satisfactory tissue welding. Similar colotomies were closed using a single layer of interrupted sutures of 5-0 Maxon (Davis & Geck, Pearl River, NY) in a control group (n = 20). Bursting pressure and index of narrowing were recorded immediately after anastomosis and at 1, 4, and 7 days following surgery. Bursting pressure of the laser-welded closure at 1 day was significantly lower than that of the sutured controls (P less than 0.01); however, all rabbits recovered uneventfully. There was a marked decrease in adhesion formation following laser anastomosis (P less than 0.05). Conversely, one control rabbit showed functional stenosis at 4 days. Histologic study revealed an accelerated healing in the laser group. The index of narrowing was significantly higher in the laser group than in the control group (P less than 0.05). The completely water-sealed laser anastomosis reduces adhesions and is comparable to conventional suture anastomosis of the colon.

Sutureless intestinal anastomoses

Sutureless intestinal anastomoses can be achieved either by compression, where two inverted rings of bowel are compressed by a hollow circular device that subsequently sloughs away and is passed anally, or by the use of tissue glues or laser welding. Compression devices used clinically with success are the Valtrac biofragmentable anastomotic ring, the polypropylene rings described by Rosati and the AKA guns. Glued anastomoses have only been used in animals and seem to be unsafe. However, laser-welded intestinal anastomoses appear highly promising in experimental studies and further development of this technique is warranted.

Canine colonic anastomoses reinforced with dye-enhanced fibrinogen and a diode laser

Leakage from colonic anastomoses is a common cause of morbidity in patients recovering from bowel surgery. We evaluated a technique of laser-fibrinogen reinforcement to strengthen colonic anastomoses in a canine model. After creation of eight single-layer interrupted suture anastomoses in six dogs, indocyanine green-dye-enhanced fibrinogen was topically applied to the serosal surface and exposed to 808 nm diode laser energy. Immediately following colonic anastomosis, the mean leakage pressure was 137 +/- 22 mm Hg in the group (n = 8) using sutures alone and 326 +/- 67 mm Hg (P less than 0.001) in the group (n = 8) after the sutured anastomosis was reinforced with lasered-fibrinogen. On histological examination, no evidence of thermal injury to the tissue edges was noted and a layer of fibrinogen bridged the anastomotic gap. Laser dye-enhanced fibrinogen reinforcement significantly enhances the strength of sutured colonic anastomoses without causing appreciable thermal injury to the host tissues.

Sutureless end-to-end bowel anastomosis using Nd:YAG and water-soluble intraluminal stent

Sutureless end-to-end intestinal anastomoses were successfully constructed in 20 rabbits. A water-soluble intraluminal stent was used to approximate the tissue edges, and the anastomotic seam was lased with 1.06 microns neodymium:YAG (Nd:YAG) laser energy supplied through a hand-held 600-microns gas-cooled noncontact optical fiber. A continuous 5-watt wave of power was applied over periods ranging from 46 to 92 seconds to produce the tissue blanching and shrinkage that indicated a satisfactory tissue weld. Integrity, degree of tissue reaction, and bursting pressures of the anastomoses were compared to those of anastomoses constructed using standard sutured techniques. The results of the two methods were equivalent at 1 to 3 days, but the laser-fused enteric anastomoses showed less inflammatory reaction and greater bursting pressures at 7 and 14 days. Application of a variety of proteinaceous solutions including extracellular matrix materials and epidermal growth factors prior to lasing failed to augment wound healing. We conclude that lasers show promise as reconstructive, in addition to ablative, surgical instruments.