Brothier (France)

ABSTRACTBackgroundPharyngoCutaneous Fistulae (PCF) represent a significant clinical challenge in otorhinolaryngology practice. The use of biomaterials could improve outcomes or even replace the use of a flap in pharyngolaryngeal surgery.MethodsThis systematic review included all studies evaluating the application of biomaterials for the prevention of PCF after pharyngeal surgery.ResultsA total of 19 articles (12 clinical and 7 animal studies) were included. They assessed the use of a biomaterial to cover mucosal sutures (n = 15) or to replace a mucosal defect and guide secondary healing (n = 4). Most studies evaluated commercialized biomaterials (n = 11) rather than experimental devices (n = 5) or platelet‐derived autologous medical devices (n = 4).ConclusionThere are already strong arguments to support the use of several biomaterials to cover pharyngeal sutures in order to decrease the rate of PCF after TL or TPL. Replacing a pharyngeal mucosal defect by a biomaterial is currently a more elusive goal.

Background:One of the major difficulties in cleft palate repair is the requirement for several surgical procedures and autologous bone grafting to form a bony bridge across the cleft defect. Engineered tissue, composed of a biomaterial scaffold and multipotent stem cells, may be a useful alternative for minimizing the non-negligible risk of donor site morbidity. The present study was designed to confirm the healing and osteogenic properties of a novel alginate-based hydrogel in palate repair.Methods:Matrix constructs, seeded with allogeneic bone marrow–derived mesenchymal stem cells (BM-MSCs) or not, were incorporated into a surgically created, critical-sized cleft palate defect in the rat. Control with no scaffold was also tested. Bone formation was assessed using microcomputed tomography at weeks 2, 4, 8, and 12 and a histologic analysis at week 12.Results:At 12 weeks, the proportion of bone filling associated with the use of hydrogel scaffold alone did not differ significantly from the values observed in the scaffold-free experiment (61.01% ± 5.288% versus 36.91% ± 5.132%; p = 0.1620). The addition of BM-MSCs stimulated bone formation not only at the margin of the defect but also in the center of the implant.Conclusions:In a relevant in vivo model of cleft palate in the rat, we confirmed the alginate-based hydrogel’s biocompatibility and real advantages for tissue healing. Addition of BM-MSCs stimulated bone formation in the center of the implant, demonstrating the new biomaterial’s potential for use as a bone substitute grafting material for cleft palate repair.

New thermothickening copolymers were synthesized by grafting responsive poly(ethylene oxide-co-propylene oxide) [PEPO] onto three different polysaccharide backbones: carboxymethylcellulose [CMC], alginate [ALG], and carboxylated dextran [DEX]. The coupling reaction between carboxylic groups of biopolymers and the terminal amine of PEPO was activated at low temperature ( T < 10 degrees C) in water by using carbodiimide and N-hydroxysuccinimide. In these conditions it was shown that the formation of amide bonds strongly depends on the concentration of reactive groups, which is limited by the viscosity of the polymer sample. While a full conversion was obtained for the low molecular weight dextran, the efficiency of grafting remains low (between 30 to 40%) for CMC and alginate, which give a solution of high viscosity even at low concentration. When studied in the semidilute regime, all the copolymer solutions clearly exhibit thermothickening behavior with a large and reversible increase of viscosity upon heating. The association temperature and the gelation threshold were shown to depend on polymer concentration as it is expected from the phase diagram of PEPO precursor. Similarly, the influence of added salt on PEPO solubility in water has been used to control the self-assembling behavior of copolymer formulations. The relative comparison between the three copolymers reveals that the amplitude of the viscosity jump induced by heating mainly depends on the proportion of responsive material inside the macromolecular architecture rather than the dimensions of the main chain. The high increase of viscosity, which can reach several orders of magnitude between 20 degrees C and body temperature, clearly demonstrates the potentiality of these copolymers in biomedical applications like injectable gels for tissue engineering.

In a prospective, randomised, controlled trial of 92 patients with full-thickness pressure ulcers, the efficacy of an alginate wound dressing was compared to that of an established local treatment with dextranomer paste. During treatment, a minimal 40% reduction in wound area was obtained in 74% of the patients in the alginate group and in 42% of those in the dextranomer group. The median time taken to achieve this goal was four weeks with alginate and more than eight weeks in the control group. Mean surface area reduction per week was 2.39cm2 (sd 3.54) and 0.27cm2 (sd 3.21) in the alginate and dextranomer groups respectively (p=0.0001). This difference was still highly significant when the sub-groups of almost completely healed subjects at the end of the study were considered. This striking healing efficacy of an alginate dressing suggests it possesses pharmacological properties which require further investigation.