Light-activated photosealing with human amniotic membrane strengthens bowel anastomosis in a hypotensive, trauma-relevant swine model

Photochemical Tissue Bonding of Amnion Allograft Membranes for Peripheral Nerve Repair: A Biomechanical Analysis

BACKGROUND

 Photochemical tissue bonding (PTB) is a technique for peripheral nerve repair in which a collagenous membrane is bonded around approximated nerve ends. Studies using PTB with cryopreserved human amnion have shown promising results in a rat sciatic nerve transection model including a more rapid and complete return of function, larger axon size, and thicker myelination than suture repair. Commercial collagen membranes, such as dehydrated amnion allograft, are readily available, offer ease of storage, and have no risk of disease transmission or tissue rejection. However, the biomechanical properties of these membranes using PTB are currently unknown in comparison to PTB of cryopreserved human amnion and suture neurorrhaphy.

METHODS

 Rat sciatic nerves (n = 10 per group) were transected and repaired using either suture neurorrhaphy or PTB with one of the following membranes: cryopreserved human amnion, monolayer human amnion allograft (crosslinked and noncrosslinked), trilayer human amnion/chorion allograft (crosslinked and noncrosslinked), or swine submucosa. Repaired nerves were subjected to mechanical testing.

RESULTS

 During ultimate stress testing, the repair groups that withstood the greatest strain increases were suture neurorrhaphy (69 ± 14%), PTB with crosslinked trilayer amnion (52 ± 10%), and PTB with cryopreserved human amnion (46 ± 20%), although the differences between these groups were not statistically significant. Neurorrhaphy repairs had a maximum load (0.98 ± 0.30 N) significantly greater than all other repair groups except for noncrosslinked trilayer amnion (0.51 ± 0.27 N). During fatigue testing, all samples repaired with suture, or PTBs with either crosslinked or noncrosslinked trilayer amnion were able to withstand strain increases of at least 50%.

CONCLUSION

 PTB repairs with commercial noncrosslinked amnion allograft membranes can withstand physiological strain and have comparable performance to repairs with human amnion, which has demonstrated efficacy in vivo. These results indicate the need for further testing of these membranes using in vivo animal model repairs.

Photosealing of dural defects using a biocompatible patch

PURPOSE

Photosealing of many biological tissues can be achieved using a biocompatible material in combination with a dye that is activated by visible light to chemically bond over the tissue defect via protein cross-linking reactions. The aim of this study was to test the efficacy of photosealing using a commercially available biomembrane (AmnioExcel Plus) to securely close dural defects in comparison to another sutureless method (fibrin glue) in terms of repair strength.

METHODS

Two-millimeter diameter holes were created in dura harvested from New Zealand white rabbits and repaired ex vivo using one of two methods: (1) in n = 10 samples, photosealing was used to bond a 6-mm-diameter AmnioExcel Plus patch over the dural defect, and (2) in n = 10 samples, fibrin glue was used to attach the same patch over the dural defect. Repaired dura samples were then subjected to burst pressure testing. Histological analysis was also performed of photosealed dura.

RESULTS

The mean burst pressures of rabbit dura repaired with photosealing and fibrin glue were 302 ± 149 mmHg and 26 ± 24 mmHg, respectively. The increased repair strength using photosealing was statistically significant and considerably higher than the normal intracranial pressure of ~ 20 mmHg. Histology demonstrated a tight union at the interface between the dura surface and patch with no disruption of the dura structure.

CONCLUSION

The results of this study suggest that photosealing performs better than fibrin glue for the fixation of a patch for ex vivo repair of small dural defects. Photosealing is worthy of testing in pre-clinical models for the repair of dural defects.

Laser tissue soldering of the gastrointestinal tract: A systematic review LTS of the gastrointestinal tract

Background

Laser Tissue Soldering (LTS) is a promising tissue bonding technique in which a solder is applied between the tissues and then irradiated by laser, causing it to solidify and form links with the tissue.

Methods

A comprehensive systematic review summarizing the state of research of LTS in the gastrointestinal tract.

Results

Most studies were conducted on large animal tissues, using liquid proteinaceous solder, and irradiated by a continuous wave laser at 808 nm. LTS can provide better sealing and burst pressure than conventional methods. The application of LTS on top of or in addition to sutures showed an impressive increase in burst pressures. LTS may decrease the inflammatory and foreign body reaction caused by sutures.

Conclusions

LTS has strong potential to be applied in a clinical setting in leak prevention and in closure of gastrointestinal structures as an adjunct or additional anastomotic technology, decreasing leak rates, morbidity, and mortality.

Application of amniotic membranes in reconstructive surgery of internal organs-A systematic review and meta-analysis

Amniotic membrane (AM) has great potential as a scaffold for tissue regeneration in reconstructive surgery. To date, no systematic review of the literature has been performed for the applications of AM in wound closure of internal organs. Therefore, in this systematic review and meta-analysis, we summarize the literature on the safety and efficacy of AM for the closure of internal organs. A systematic search was performed in MEDLINE-PubMed database and OVID Embase to retrieve human and controlled animal studies on wound closure of internal organs. The Cochrane Risk of Bias tool for randomized clinical trials and the SYRCLE risk of bias tool for animal studies were used. Meta-analyses (MAs) were conducted for controlled animal studies to assess efficacy of closure, mortality and complications in subjects who underwent surgical wound closure in internal organs with the application of AM. Sixty references containing 26 human experiments and 36 animal experiments were included. The MAs of the controlled animal studies showed comparable results with regard to closure, mortality and complications, and suggested improved mechanical strength and lower inflammation scores after AM application when compared to standard surgical closure techniques. This systematic review and MAs demonstrate that the application of AM to promote wound healing of internal organs appears to be safe, efficacious, and feasible.