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Chemically synthesized poly(4-hydroxybutyrate) (P4HB) is a new generation of biomass-derived and degradable semi-crystalline polymer with good comprehensive properties, but high costs limit its application. Starch, as an inexpensive natural polymer, can reduce the cost of P4HB products. However, starch lacks thermoplastic behavior and has poor compatibility with P4HB, thus its extensive use will inevitably impair the mechanical properties of P4HB. In this study, the ball-milling starch grafting process is adopted, which can simultaneously solve the two major deficiencies of starch, and the prepared ball-milling starch-g-polycaprolactone (BSt-g-PCL) has thermoplasticity and better compatibility with P4HB. BSt-g-PCL can melt near 55 °C, and the interweaving of its molecular chains with P4HB reduces the binding energy (Einteraction) of both, making the phase interface blurred or even disappear. Therefore, the elongation at break retention (REB) of P4HB/BSt-g-PCL can increase from 37.1 % to 74.3 % compared to P4HB/starch at the same filling (70 Phr). Additionally, BSt-g-PCL can exert the effect of accelerating P4HB degradation and still make it maintain excellent anti-aging ability. The ball-milling starch graft process provides a simple and effective method for the preparation of inexpensive fully biodegradable P4HB composite films with excellent mechanical properties.

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Dental implant surgery is a procedure that replaces damaged or missing teeth with an artificial implant. During this procedure, guided bone regeneration (GBR) membranes are commonly used to inhibit the migration of epithelium and GBR at the surgical sites. Due to its biodegradability, good biocompatibility, and unique biological properties, gelatin (GT) is considered a suitable candidate for guiding periodontal tissue regeneration. However, GT-based membranes come with limitations, such as poor mechanical strength and mismatched degradation rates. To confront this challenge, a series of GT/poly(4-hydroxybutyrate) (P4HB) composite membranes are fabricated through electrospinning technology. The morphology, composition, wetting properties, mechanical properties, biocompatibility, and in vivo biodegradability of the as-prepared composite membranes are carefully characterized. The results demonstrate that all the membranes present excellent biocompatibility. Moreover, the in vivo degradation rate of the membranes can be manipulated by changing the ratio of GT and P4HB. The results indicate that the optimized GT/P4HB membranes with a high P4HB content (75%) may be suitable for periodontal tissue engineering because of their good mechanical properties and biodegradation rate compatible with tissue growth.

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PURPOSE/BACKGROUND: Despite the growing use of bioabsorbable mesh in ventral hernia repairs (VHR), the evidence of its impact on patient outcomes remains limited. This study aims to investigate the efficacy and safety profile of poly-4-hydroxybutyrate (P4HB) mesh for ventral hernia repair through a systematic review and meta-analysis. METHODS: A literature search of five databases (PubMed, Embase, Ovid, Medline, and Google Scholar) produced a list of publications that analyzed the use of P4HB mesh in ventral hernia repair in both clean and contaminated cases. The primary postoperative outcomes of hernia recurrence, surgical site infections (SSI), and any complications were analyzed through a pooled meta-analysis. RESULTS: In our systematic review, 21 studies met the inclusion criteria with a total of 1858 patients (933 males and 925 females) and an average age of 56.8 years. The median follow-up ranged from 1.6 to 62.3 months. In our meta-analysis, the use of P4HB mesh in VHR in proportion of events demonstrated a recurrence rate of 9% [6%; 15%], SSI of 10% [6%; 16%] and 35% [9%; 42%] for rate of any complications. Sub-meta-analysis restricted to studies with follow up > 18 months continues to show low rates of recurrence of 9% (95%CI, 4-17%), SSI of 9% (95%CI, 4-16%), and 31% (95%CI, 23-41%) for any complications. CONCLUSION: Our study demonstrates that the use of P4HB mesh is both safe and effective in ventral hernia repairs. When further analyzed past 18 months, the time where P4HB mesh fully resorbs, the rates of hernia recurrence, SSI, and any complications remain low of upwards of 5 years and comparable to the rates seen in synthetic and biologics in similar patient populations.

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INTRODUCTION AND HYPOTHESIS: Fully absorbable implants may be an alternative to permanent meshes in the correction pf pelvic organ prolapse (POP) as they may reduce adverse events by promoting tissue regeneration and collagen metabolism. This study was aimed at evaluating the long-term host and biomechanical response to a fully absorbable poly-4-hydroxybutyrate (P4HB) scaffold in comparison with polypropylene (PP) mesh. METHODS: Poly-4-hydroxybutyrate scaffold (n = 16) and PP mesh (n = 16) were surgically implanted in the posterior vaginal wall of parous female Dohne Merino sheep. Vaginal explants were evaluated in terms of gross necropsy, host response (immune response, collagen deposition, tissue regeneration), biomechanics, and degradation of P4HB at 12 and 24 months post-implantation. RESULTS: Gross necropsy revealed no infection or fluid collection using P4HB or PP. At 12 months, exposures were observed with both P4HB (3 out of 8) and PP (4 out of 8), whereas at 24 months, exposures were observed only with PP (4 out of 8). The tensile stiffness of the P4HB explants was maintained over time despite complete absorption of P4HB. The collagen amount of the vaginal tissue after P4HB implantation increased over time and was significantly higher than PP at 24 months. P4HB scaffolds exhibited significantly lower myofibroblast differentiation than PP meshes at 24 months. CONCLUSIONS: The P4HB scaffold allowed for gradual load transfer to the vaginal wall and resulted in mechanically self-sufficient tissue. P4HB scaffold had a more favorable host response than PP mesh, with higher collagen content, lower myofibroblastic differentiation, and no exposures at 24 months. P4HB scaffolds have potential as an alternative to permanent implants in treating POP.

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Scaffolds can be introduced as a source of tissue in reconstructive surgery and can help to improve wound healing. Amniotic membranes (AMs) as scaffolds for tissue engineering have emerged as promising biomaterials for surgical reconstruction due to their regenerative capacity, biocompatibility, gradual degradability, and availability. They also promote fetal-like scarless healing and provide a bioactive matrix that stimulates cell adhesion, migration, and proliferation. The aim of this study was to create a tissue-engineered AM-based implant for the repair of vesicovaginal fistula (VVF), a defect between the bladder and vagina caused by prolonged obstructed labor. Layers of AMs (with or without cross-linking) and electrospun poly-4-hydroxybutyrate (P4HB) (a synthetic, degradable polymer) scaffold were joined together by fibrin glue to produce a multilayer scaffold. Human vaginal fibroblasts were seeded on the different constructs and cultured for 28 days. Cell proliferation, cell morphology, collagen deposition, and metabolism measured by matrix metalloproteinase (MMP) activity were evaluated. Vaginal fibroblasts proliferated and were metabolically active on the different constructs, producing a distributed layer of collagen and proMMP-2. Cell proliferation and the amount of produced collagen were similar across different groups, indicating that the different AM-based constructs support vaginal fibroblast function. Cell morphology and collagen images showed slightly better alignment and organization on the un-cross-linked constructs compared to the cross-linked constructs. It was concluded that the regenerative capacity of AM does not seem to be affected by mechanical reinforcement with cross-linking or the addition of P4HB and fibrin glue. An AM-based implant for surgical repair of internal organs requiring load-bearing functionality can be directly translated to other types of surgical reconstruction of internal organs.

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BACKGROUND: Poly-4-hydroxybutyrate (P4HB) is a bioabsorbable mesh with a non-adhesive coating on one side that is being used to reinforce the hiatus during hiatal hernia repair; however, there is limited data regarding its use. The aim of this study was to investigate outcomes after hiatal hernia repair using this mesh at our institution and through a review of the literature. METHODS: An institutional review board-approved prospective database was retrospectively reviewed for all patients undergoing hiatal hernia repair from April 2018 to December 2022. A systematic review with meta-analysis was conducted to evaluate outcomes using P4HB coated mesh. RESULTS: In our institutional cohort, there were 230 patients (59 males; 171 females) with a mean follow-up of 20 ± 14.6 months. No mesh-related complications occurred. Hernia recurrence was diagnosed in 11 patients (4.8%) with a median time to recurrence of 16 months. In the systematic review, 4 studies with 221 patients (76 males; 145 females) were included. Median follow-up ranged from 12 to 27 months. Recurrence rate in these studies was reported from 0 to 8.8%, with a total of 12 recurrences identified. Like our institutional cohort, no mesh-related complications were reported. After our recurrences were combined with those from the systematic review, a total of 23 recurrences were included in the meta-analysis. Our meta-analysis revealed a low recurrence rate following hiatal hernia repair with P4HB coated mesh (incidence rate per 100 person-years, 2.82; 95% confidence interval, 1.60, 4.04). CONCLUSION: P4HB coated mesh is safe and effective for hiatal hernia repairs.

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Background: Permanent synthetic meshes such as polypropylene (PP) have been utilized for hernia repair for decades, but concerns remain regarding potential long-term, mesh-related complications. A resorbable polymer such as poly-4-hydroxybutyrate (P4HB) represents an alternative with high initial strength, that gradually resorbs, leaving an abdominal wall that is at least as strong as it would be in its native state. We aimed to compare early wound morbidity and clinical outcomes associated with P4HB to traditional, permanent PP in umbilical and small to medium, routine ventral hernias using data from the Abdominal Core Health Quality Collaborative (ACHQC). Methods: Inclusion criteria for the umbilical cohort included: all Centers for Disease Control and Prevention (CDC) wound classes, all Ventral Hernia Working Group (VHWG) hernia grades, and hernia defects <3 cm. The small to medium, routine ventral hernia cohort was limited to CDC class I wounds, VHWG hernia grades I and II, and hernia defects <5 cm. The study group was comprised of P4HB meshes; the comparator group was an aggregate of PP meshes. Clinical outcomes were assessed at 30 days. Results: There was no significant difference in early wound morbidity, readmission, or reoperation between the P4HB and PP cohorts. A small number of patients experienced SSO, with ≤4% requiring procedural intervention. None of the patients (0% in all cases) experienced skin/soft tissue necrosis, infected seroma, infected hematoma, exposed/contaminated/infected mesh, enterocutaneous fistula, graft failure, or pain requiring intervention at 30-days. However, P4HB was associated with significantly greater operative time, length of stay, and use of myofascial release compared to PP (p < 0.05 in all cases). Conclusions: Short-term clinical outcomes associated with resorbable P4HB mesh are comparable to permanent synthetic PP mesh in umbilical and small to medium, routine ventral hernia repairs, despite significant differences in operative time and length of stay. Longer-term follow-up is needed to expand on the clinical relevance of these short-term findings.

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Background: Poly-4-hydroxybutyrate (P4HB) (Phasix) biosynthetic mesh was recently introduced as an alternative to synthetic and biologic meshes for ventral hernia repair (VHR). However, outcomes data are limited. This study aims to analyze outcomes of VHR with P4HB mesh and identify predictors of postoperative outcomes. Methods: We performed a retrospective study of adults who underwent open VHR with P4HB by the senior author from 2014 to 2020 with >12 months' follow-up. Subgroup comparisons and multivariate logistic regression were performed. Results: Inclusion criteria were met by 169 patients with a median of 15 months of follow-up. Overall, 21.9% had surgical site occurrences, 17.8% required reoperation, and 4.7% had recurrences. Patients with prior VHR (47.9%) experienced similar outcomes to those without. Patients with prior mesh infection (18.3%) had higher rates of postoperative mesh infection (6.5% vs 0.7%; P = .029) but did not have higher rates of reoperation. Retrorectus repairs (45.5%) had similar outcomes to onlay repairs (54.5%). Recurrence risk was increased by hypertension (odds ratio [OR] = 13.64; P = .046), immunosuppression (OR = 42.57; P = .004), and history of prior VHR (OR = 20.20; P = .014). Conclusions: This study aimed to analyze outcomes of VHR augmented with P4HB mesh through retrospective review. VHR with P4HB mesh produces acceptable recurrence rates with favorable complication risks compared with biologic and synthetic meshes. Predictors of recurrence include a history of prior hernia repair, hypertension, and immunosuppression. A history of prior mesh infection seems to place patients at risk for developing subsequent infection but did not increase need for reoperation.

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Background: Poly-4-hydroxybutyrate (P4HB) is a fully resorbable, biologically-produced polymer with a strength and flexibility comparable to permanent synthetic polymers. The objective was to identify/summarize all peer-reviewed publications involving P4HB mesh. Methods: A scoping review was conducted within PubMed and included articles published through October 2022. Results: A total of n = 79 studies were identified (n = 12 in vitro/bench; n = 14 preclinical; n = 6 commentaries; n = 50 clinical). Of the clinical studies, n = 40 reported results applicable to hernia and n = 10 to plastic/reconstructive surgery and involved patients of all Centers for Disease Control (CDC) wound classes and Ventral Hernia Working Group (VHWG) grades. Conclusion: P4HB mesh provides long-term hernia repair strength and exhibits promising clinical outcomes beyond its resorption period. Future studies should include randomized controlled trials comparing P4HB to other biomaterials, as well as optimal patient selection, operative technique, long-term outcomes, minimization of potential mesh-related complications, and potential contraindications/complications for P4HB in hernia/abdominal wall reconstruction.

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Abdominal wall defect caused by surgical trauma, congenital rupture, or tumor resection may result in hernia formation or even death. Tension-free abdominal wall defect repair by using patches is the gold standard to solve such problems. However, adhesions following patch implantation remain one of the most challenging issues in surgical practice. The development of new kinds of barriers is key to addressing peritoneal adhesions and repairing abdominal wall defects. It is already well recognized that ideal barrier materials need to have good resistance to nonspecific protein adsorption, cell adhesion, and bacterial colonization for preventing the initial development of adhesion. Herein, electrospun poly(4-hydroxybutyrate) (P4HB) membranes infused with perfluorocarbon oil are used as physical barriers. The oil-infused P4HB membranes can greatly prevent protein attachment and reduce blood cell adhesion in vitro. It is further shown that the perfluorocarbon oil-infused P4HB membranes can reduce bacterial colonization. The in vivo study reveals that perfluoro(decahydronaphthalene)-infused P4HB membranes can significantly prevent peritoneal adhesions in the classic abdominal wall defects' model and accelerate defect repair, as evidenced by gross examination and histological evaluation. This work provides a safe fluorinated lubricant-impregnated P4HB physical barrier to inhibit the formation of postoperative peritoneal adhesions and efficiently repair soft-tissue defects.

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INTRODUCTION: Amniotic membranes (AM) have shown its great potential in reconstructive surgery due to their regenerative capacity. However, AM is regarded to be relatively weak when applied for load-bearing purposes. This study aims to produce an AM-based scaffold that can withstand the mechanical loads applied in vesicovaginal fistula repair. Different strategies are investigated to improve the mechanical characteristics of AM. METHODS: Single and multilayered AM, and composite constructs of AM with electrospun poly-4-hydroxybutyrate (P4HB) or bovine pericardial tissue combined with the use of fibrin glue, were mechanically tested in this study. Suture retention strength and mechanical characteristics (tensile stress, elongation, tangent modulus and maximum load) were assessed by uniaxial testing. The effect of degradation of the composite constructs on the mechanical characteristics was determined by uniaxial testing after 4 and 8 weeks. RESULTS: Single and multilayered AM could not provide the mechanical requirements needed for surgical implantation (>2N load). AM was combined successfully with electrospun P4HB and bovine pericardium with the use of fibrin glue and were able to exceed the 2N load. CONCLUSION: The composite constructs with AM showed sufficient mechanical characteristics for surgical implantation. Electrospun P4HB combined with AM seemed the most promising candidate since the mechanical characteristics of P4HB can be further modified to meet the requirements of the application site and the degradation of the P4HB allows a gradual transfer of load. Eventhough the scaffold is intended for fistula repair, it can potentially be applied in surgical reconstruction of other hollow organs by modifying the mechanical characteristics.

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The low temperature condition, long reaction time and associated high energy inputs involved in the polymerization process still hampered the scalable production of poly(γ-butyrolactone) (PγBL) via ring-opening polymerization (ROP) of low strained γBL due to its unfavorable thermodynamics. In this contribution, we presented the rapid ROP of γBL using a bisurea in combination with an organophosphazene base as the binary catalyst. Well-defined PγBL samples with various terminal groups were prepared by using different alcohol initiators. The bisurea as a co-catalyst exhibited much higher catalytic activity even compared to the most active monourea in previous report as supported by the kinetic experiments. A moderate monomer conversion of 61% was achieved within 10 mins, producing high-molecular-weight PγBL with Mn up to 37.5 kDa and good mechanical properties. The short polymerization time considerably reduced the energy cost for the ROP of γBL conducted at low temperature condition. This study may clear away obstacles for the scalable production and practical applications for PγBL.

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Women with pelvic organ prolapse (POP) have bothersome complaints that significantly affect their quality of life. While native tissue repair is associated with high recurrence rates, polypropylene knitted implants have caused specific implant-related adverse events that have detrimental, often irreversible, effects. We hypothesize that surgical outcome can be improved with a tissue-engineered solution using an absorbable implant that mimics the natural extracellular matrix (ECM) structure, releases estrogen, and activates collagen metabolism by fibroblasts as the main regulators of wound healing. To this aim, we produced electrospun poly-4-hydroxybutyrate (P4HB) scaffolds and biofunctionalized them with estradiol (E2). The cell-implant interactions relevant for POP repair were assessed by seeding primary POP vaginal fibroblasts isolated from patients on electrospun P4HB scaffolds with 1%, 2%, or 5% E2 and without E2. To test our hypothesis on whether ECM mimicking structures should improve regeneration, electrospun P4HB was compared to knitted P4HB implants. We evaluated vaginal fibroblast proliferation, ECM deposition, and metabolism by quantification of collagen, elastin, and matrix metalloproteinases and by gene expression analysis for 28 days. We established effective E2 drug loading with a steady release over time. Significantly higher cell proliferation, collagen-, and elastin deposition were observed on electrospun P4HB scaffolds as compared to knitted P4HB. For this study, physical properties of the scaffolds were more determinant on the cell response than the release of E2. These results indicate that making these electrospun P4HB scaffolds E2-releasing appears to be technically feasible. In addition, electrospun P4HB scaffolds promote the cellular response of vaginal fibroblasts and further studies are merited to assess if their use results in improved surgical outcomes in case of POP repair.

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PURPOSE: Ventral hernia repair (VHR) can be augmented with biosynthetic poly-4-hydroxybutryate mesh (P4HB). Long-term outcomes, including quality of life outcomes, after VHR with P4HB mesh are not well established. Our study sought to assess these outcomes 5 years after repair. METHODS: Patients who received VHR using P4HB by the senior author between 01/2015 and 09/2017 were retrospectively identified. Patients were prospectively interviewed for quality of life assessment using the Hernia-Related Quality-of-Life Survey (HerQLes) and Abdominal Hernia-Q (AHQ) and screened for recurrence. Those who screened positive were asked to follow up in clinic to confirm recurrence. Both 5-year quality of life and recurrence were univariately assessed with patient and operative factors. RESULTS: 51 patients met inclusion criteria. 43 patients completed 5-year quality of life assessment (84.3% response rate). Quality of life scores at all postoperative time periods were greater than preoperative scores. Further, quality of life at 5 years is greater than that assessed 0-2 years following VHR. Most patients achieve their best quality of life in the 5-year time period. Thirty-five patients had clinical follow-up in the 5-year time period, 7 experienced recurrences (20% recurrence rate). There was no difference in 5-year quality of life assessment between those who had a recurrence and those who did not. CONCLUSION: Patient quality of life following VHR with P4HB improves immediately and continues to improve 5 years following repair. There are no differences in quality of life with onset of recurrence. Quality of life should be the primary outcome of success in VHR.

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ABSTRACT Background Poly-4-hydroxybutyrate (P4HB) is a naturally occurring polymer derived from transgenic E. coli bacteria with the longest degradation rate when compared to other available products. This polymer has been manufactured as a biosynthetic mesh to be used as reinforcement when repairing a variety of abdominal wall defects. Objective: We aim to describe our center initial experience with this mesh and discuss the possible indications that may benefit from the use of P4HB mesh. Methods: This is a descriptive retrospective study of patients who underwent abdominal wall repair with a P4HB mesh from October 2018 to December 2020 in a single, large volume, academic center. Results: A total of 51 patients (mean age 54.4 years, range 12-89) underwent abdominal wall reconstruction with a P4HB mesh between October 2018 and December 2020. The mean BMI was 30.5 (range 17.2-50.6). Twenty-three (45%) patients had a prior hernia repair at the site. We grouped patients into six different indications for the use of P4HB mesh in our cohort: clean-contaminated, contaminated or infected field (57%), patient refusal for permanent meshes (14%), those with high risk for post-operative infection (12%), visceral protection of second mesh (10%), recurrence with related chronic pain from mesh (6%), and children (2%). Median follow-up was 105 days (range 8-648). Two patients had hernia recurrence (4%) and 8 (16%) patients developed seroma. Conclusion: P4HB mesh is a safe and a viable alternative for complex hernias and high-risk patients with a low complication rate in the short-term.

RESUMO Contexto: 4-Polihidroxibutirato (P4HB) é um polímero natural derivado da E. coli transgênica que tem a mais longa taxa de degradação quando comparado a outros produtos. Este polímero é manufaturado como uma tela biossintética a ser usada como um reforço no reparo de uma variedade de defeitos de parede abdominal. Objetivo: O objetivo deste estudo é descrever nossa experiência inicial com esta tela e discutir suas possíveis indicações. Métodos: Estudo retrospectivo e descritivo com pacientes que foram submetidos a cirurgia de reconstrução de parede abdominal de outubro de 2018 a dezembro de 2020 em um grande centro acadêmico. Resultados: Cinquenta e um pacientes, média de 54,4 anos (12-89) foram submetidos a reconstrução da parede abdominal com tela de P4HB entre outubro de 2018 e dezembro de 2020. O índice de massa corpórea médio foi de 30,5 kg/m2(17,2-50,6). Vinte e três pacientes (45%) tinham cirurgia prévia de hérnia no mesmo local. Nós agrupamos pacientes em seis diferentes indicações para o uso da tela de P4HB: campo limpo-contaminado, contaminado, infectado (57%), recusa do paciente em telas permanentes (14%), pacientes com alto risco de infecção no pós-operatório (12%), proteção visceral de contato com outra tela (10%), recidiva da hérnia associada com dor crônica relacionada a tela anterior (6%) e pacientes pediátricos (2%). O seguimento mediano foi de 105 dias (8-648). Dois pacientes tiveram recidiva (4%) e 8 (16%) desenvolveram seroma. Conclusão: O uso da tela de P4HB se mostrou uma alternativa segura e viável com baixa taxa de complicações para estes pacientes no curto prazo.

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Polypropylene (PP) implants for the vaginal surgical correction of pelvic organ prolapse (POP) are known for adverse events, like vaginal or visceral exposures. It is hypothesized that this is a result of a prolonged inflammatory response. One of the triggering factors of prolonged inflammation might be bacterial contamination. A possible solution might lie in an absorbable biomaterial, which provides initial mechanical support while being gradually replaced by the host tissue. With this study we aimed to compare the host response, in a subcutaneous mouse implant infection model, to delayed absorbable poly-4-hydroxybutyrate (P4HB) and a latest generation PP implant. By comparing non-infected to Staphylococcus aureus infected mice, we assessed how bacterial contamination affects the host response and its role in the development of complications. Further, we included sham surgery as a control, mimicking the wound response in native tissue repair. Despite the higher surface area of the P4HB implants, the clearance of infection was similarly delayed in the presence of a P4HB or PP implant, as compared to sham. Further, the host response towards P4HB and PP was quite comparable, yet collagen deposition was significantly increased around infected P4HB implants at early time points. Adverse event rates were similar, though implant exposures were only seen in infected mice and more often with PP (11.1%) than P4HB implants (5.6%). Infected mice overall had significantly higher levels of infiltration of inflammatory cells and lower levels of vascularization and collagen deposition compared to non-infected mice. Thus, for both P4HB and PP, bacterial contamination negatively affected mesh integration by increased inflammation and an increased adverse event rate. Altogether, our results from this subcutaneous mouse implant infection study suggest that P4HB could be a promising degradable alternative to PP, warranting further research to study its potential as a new surgical solution for women with POP.

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Antibacterial and hemostatic properties are of great importance to wound dressing in treating trauma. Poly(4-hydroxybutyrate) (P4HB), an U.S. Food and Drug Administration (FDA)-approved bioabsorbable polyester, is used as dermal substitutes to prevent sever wound contraction and improve wound healing. However, P4HB fibrous mats are not efficient in halting bleeding and preventing bacterial associated infection. Here the authors prepare a new kind of wound dressing by incorporating poly(ethylene glycol) (PEG) and zinc oxide (ZnO) nanoparticles into the P4HB matrix by using electrospinning method. The in vitro results reveal that the P4HB/PEG/ZnO dressings can synergistically help blood clotting, prevent bacteria adhesion, and kill bacteria efficiently. It's found that the bactericidal activity of the bioactive P4HB/PEG/ZnO dressings is related to the release of Zn2+ ions rather than reactive oxygen species (ROS) under dark condition. The in vivo antibacterial evaluation indicates that the bioactive P4HB/PEG/ZnO dressings can successfully prevent wound infections in Sprague-Dawley (SD) rats' skin defect model. The in vivo hemostatic experiments evaluated in the rabbit ear injury model further confirm that the bioactive P4HB/PEG/ZnO dressings have excellent hemostatic performance. Hence, this study demonstrates that the bioactive P4HB/PEG/ZnO dressings with hemostatic and bactericidal properties have great potential in possible clinical applications.

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BACKGROUND: This prospective, multicenter, single-arm, open-label study evaluated P4HB-ST mesh in laparoscopic ventral or incisional hernia repair (LVIHR) in patients with Class I (clean) wounds at high risk for Surgical Site Occurrence (SSO). METHODS: Primary endpoint was SSO requiring intervention <45 days. Secondary endpoints included: surgical procedure time, length of stay, SSO >45 days, hernia recurrence, device-related adverse events, reoperation, and Quality of Life at 1, 3, 6, 12, 18, and 24-months. RESULTS: 120 patients (52.5% male), mean age of 55.0 ± 14.9 years, and BMI of 33.2 ± 4.5 kg/m2 received P4HB-ST mesh. Patient-reported comorbid conditions included: obesity (86.7%), active smoker (45.0%), COPD (5.0%), diabetes (16.7%), immunosuppression (2.5%), coronary artery disease (7.5%), chronic corticosteroid use (2.5%), hypoalbuminemia (0.8%), advanced age (10.0%), and renal insufficiency (0.8%). Hernia types were primary ventral (44.2%), primary incisional (37.5%), recurrent ventral (5.8%), and recurrent incisional (12.5%). Patients underwent LVIHR in laparoscopic (55.8%) or robotic-assisted cases (44.2%), mean defect size 15.7 ± 28.3 cm2, mean procedure time 85.9 ± 43.0 min, and mean length of stay 1.0 ± 1.4 days. There were no SSOs requiring intervention beyond 45 days, n = 38 (31.7%) recurrences, n = 22 (18.3%) reoperations, and n = 2 (1.7%) device-related adverse events (excluding recurrence). CONCLUSION: P4HB-ST mesh demonstrated low rates of SSO and device-related complications, with improved quality of life scores, and reoperation rate comparable to other published studies. Recurrence rate was higher than expected at 31.7%. However, when analyzed by hernia defect size, recurrence was disproportionately high in defects ≥7.1 cm2 (43.3%) compared to defects <7.1 cm2 (18.6%). Thus, in LVIHR, P4HB-ST may be better suited for small defects. Caution is warranted when utilizing P4HB-ST in laparoscopic IPOM repair of larger defects until additional studies can further investigate outcomes.

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PURPOSE: The objective of this study was to determine mechanical and histological properties of Phasix™ ST Mesh in various defect sizes and characterize the tissue replacing Phasix™ ST Mesh in a porcine model of ventral hernia repair. METHODS: Simulated hernia defects were surgically created in the midline of twenty-four (n = 24) Yucatan pigs. Treatment groups included 8 cm defect sutured closed (buttress) and unclosed 4 cm and 8 cm defect groups. Phasix™ ST Mesh (15 cm diameter circle) was implanted laparoscopically and fixated circumferentially with SorbaFix™ Absorbable Fixation System fasteners. The repair sites underwent mechanical, molecular weight, and histological evaluation at 48 and 72 weeks postimplantation. RESULTS: Mechanical testing of Phasix™ ST Mesh-repaired sites revealed similar strengths at both time points for all three repair types, p > 0.05 in all cases (48 weeks: 142.4 ± 6.0 N, 142.3 ± 16.5 N, and 168.8 ± 38.5 N; 72 weeks: 110.0 ± 18.3 N, 138.6 ± 42.2 N, and 160.6 ± 42.0 N for 4 cm defect, 8 cm defect, and 8 cm buttress, respectively. mean ± SEM) No significant differences were observed over time except at 72 weeks postimplantation when the 4 cm defect group exhibited significantly lower strength than the T0 strength of Phasix™ ST Mesh (204.6 ± 5.0 N, p < 0.05). The molecular weight of Phasix™ ST Mesh decreased over time, regardless of repair type. Histological analysis showed comparable mature collagen/fibrovascular tissue around and within the Phasix™ ST Mesh interstices, including the segment of mesh overlying the defect. CONCLUSION: Phasix™ ST Mesh-repaired sites exhibited similar mechanical strengths and histological properties across all defect sizes in this porcine model.

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OBJECTIVE: To evaluate the host- and biomechanical response to a fully absorbable poly-4-hydroxybutyrate (P4HB) scaffold in comparison with the response to polypropylene (PP) mesh. DESIGN: In vivo animal experiment. SETTING: KU Leuven Center for Surgical Technologies. POPULATION: Fourteen parous female Mule sheep. METHODS: P4HB scaffolds were surgically implanted in the posterior vaginal wall of sheep. The comparative PP mesh data were obtained from an identical study protocol performed previously. MAIN OUTCOME MEASURES: Gross necropsy, host response and biomechanical evaluation of explants, and the in vivo P4HB scaffold degradation were evaluated at 60- and 180-days post-implantation. Data are reported as mean ± standard deviation (SD) or standard error of the mean (SEM). RESULTS: Gross necropsy revealed no implant-related adverse events using P4HB scaffolds. The tensile stiffness of the P4HB explants increased at 180-days (12.498 ± 2.66 N/mm SEM [p =0.019]) as compared to 60-days (4.585 ± 1.57 N/mm) post-implantation, while P4HB degraded gradually. P4HB scaffolds exhibited excellent tissue integration with dense connective tissue and a moderate initial host response. P4HB scaffolds induced a significantly higher M2/M1 ratio (1.70 ± 0.67 SD, score 0-4), as compared to PP mesh(0.99 ± 0.78 SD, score 0-4) at 180-days. CONCLUSIONS: P4HB scaffold facilitated a gradual load transfer to vaginal tissue over time. The fully absorbable P4HB scaffold, in comparison to PP mesh, has a favorable host response with comparable load-bearing capacity. If these results are also observed at longer follow-up in-vivo, a clinical study using P4HB for vaginal POP surgery may be warranted to demonstrate efficacy. TWEETABLE ABSTRACT: Degradable vaginal P4HB implant might be a solution for treatment of POP.

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