The Regenerative Capacity of Tissue-Engineered Amniotic Membranes.

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.

The Microcirculation of Vaginal Tissue in Women with Obstetric Vesicovaginal Fistula and Short-Term Effects of Surgical Repair on Microvascular Parameters.

OBJECTIVES: The objective of the study was to better understand the extent of the ischemic trauma and the effects of surgical repair on the vaginal microcirculation in patients with obstetric vesicovaginal fistula (VVF). DESIGN: In this observational study, we evaluated the vaginal microvasculature surrounding VVF using handheld vital microscopy (HVM) before, during, and 2 weeks after surgical VVF repair. PARTICIPANTS: Seventeen women undergoing VVF repair were included in this study. SETTING: The study was conducted in the Fistula Care Centre in Lilongwe, Malawi. METHODS: We used HVM with incident dark-field imaging to non-invasively visualize the microvasculature of the vaginal tissue surrounding fistulas. The primary outcome was the presence of microvascular flow. Secondary outcomes included angioarchitecture, fistula closure (postoperative dye test), and urinary continence (pad weight test). RESULTS: Microvascular flow was present before, during, and after surgical repair in, respectively, 83.8%, 83.9%, and 93.4% of obtained image sequences. The angioarchitecture was normal in 75.8% of the image sequences before surgery, 69.4% at fistula closure, and 89.1% two weeks after VVF repair. Fourteen (82.4%) patients had a closed fistula after surgical repair. LIMITATIONS: The study was limited by the lack of a control group and the relatively small sample size. CONCLUSION: Although the vaginal microcirculation in women with VVF is compromised, extensive ischemic damage is not observed in the tissue surrounding fistulas. This suggests significant regenerative capacity of the vaginal vasculature in young women, or less extensive ischemic damage than presumed. Following surgical repair, we observed improvement of microcirculatory flow and angioarchitecture, suggesting that surgery is a good option for patients with obstetric VVF.

Predictors of outcomes in patients with repeat surgery for obstetric fistula: a retrospective review.

INTRODUCTION AND HYPOTHESIS: Predictors of surgical outcomes in patients with an obstetric fistula who have been operated before should be identified in order to guide surgical strategy and optimize counseling of the patient. METHODS: This retrospective study is aimed at identifying predictors of outcomes for repeat surgery in 346 patients who had been operated on before for an obstetrics fistula at the Fistula Care Center (FCC) in Lilongwe, Malawi. Repeat cases were only undertaken by advanced and expert surgeons. The primary outcome was successful anatomical closure, based on a negative postoperative dye test. The secondary outcomes involved urinary continence, based on a patient-reported questionnaire and an objective 1-h pad weight test. Logistic regression models were used to test the predictors for statistical significance. RESULTS: Successful fistula closure was achieved in 288 (83%) patients and continence was achieved in 185 (64%) patients after the first repeat attempt at the FCC. Lack of urethral involvement (Goh classification: proximity to the urethra) was shown to be a good predictor of the outcomes: fistula closure and subjective and objective continence. CONCLUSIONS: Absence of urethral involvement is an independent predictor for successful outcomes in repeat surgery for obstetric fistulas. Even in the hands of an expert surgeon, the risk of another failure in achieving anatomical closure or subjective or objective continence is between 4 and 5 times higher than when the urethra is not involved.

Mechanical reinforcement of amniotic membranes for vesicovaginal fistula repair.

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.

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.

Validation of an ovine vesicovaginal fistula model.

INTRODUCTION AND HYPOTHESIS: A representative, large animal model of vesicovaginal fistulas is needed for the training of surgeons and for the development of new surgical techniques and materials for obstetric fistula repair. METHODS: The safety, feasibility, and reproducibility of vesicovaginal fistula creation were studied in 4 adult female sheep. A 1-cm fistula was created between the vagina and the bladder through a transvaginal approach. The defect was allowed to heal for 8 weeks and the animals were then euthanized. The primary outcome was the fistula patency. Secondary outcomes were fistula size, urogenital dimensions, urodynamic evaluation, histology (inflammation, vascularization, collagen deposition) and biomechanical characteristics of the fistula edge (stress at break, maximum elongation, and stiffness). RESULTS: The transvaginal creation of a vesicovaginal fistula was safe. All animals survived the surgical procedure and follow-up period, without complications. Three of the four animals demonstrated a patent vesicovaginal fistula after 8 weeks. Baseline data are provided of the urogenital dimensions and the urodynamic, histological, and biomechanical characteristics of the model. CONCLUSIONS: The ewe is a safe, feasible, and reproducible model for vesicovaginal fistulas. The model can help to study new techniques and materials to boost surgical innovation for vesicovaginal fistula repair.

Follow-up of obstetric fistula repair using Singapore fasciocutaneous flap and/or gracilis muscle flap.

AIMS: To report on the follow-up of obstetric fistula repair using vascularized surgical flaps, namely the Singapore fasciocutaneous flap, the gracilis muscle flap, or a combination of both. METHODS: This cross-sectional study reports on the follow-up of 60 patients after fistula repair with a vascularized surgical flap at the Fistula Care Center in Lilongwe, Malawi. The primary outcome was fistula closure based on patients' self-reported continence grade. Secondary outcomes were urinary incontinence based on a 1-h pad-weight test, quality of life based on the Incontinence Quality of Life (I-QOL) questionnaire, surgical complications, and the indication for additional surgery after repair. RESULTS: Successful closure was achieved in 62% of cases and full continence was achieved in 12% of cases. Incontinence based on a 1-h pad weight test improved between surgery and follow-up. QOL scores based on the I-QOL were low but patients indicated moderate to great improvement in quality of life. Twenty-two (37%) patients experienced surgical complication, mostly minor wound breakdowns. No major complications were reported. Six (10%) patients were indicated for additional surgery during follow-up. CONCLUSION: The relative safety of the surgical procedures is shown in the findings of this study, including no reports on major complications during follow-up. Vascularized flaps should be considered in complex fistula cases, especially in repeat cases and before considering urinary diversion as a last resort.

Condom migration after introduction of pre-exposure prophylaxis among HIV-uninfected adolescents in South Africa: A cohort analysis.

BACKGROUND: Approximately 3 million adolescents and young adults (AYA), between the ages of 15 years and 24 years, are living with HIV in sub-Saharan Africa. The use of pre-exposure prophylaxis (PrEP) may be a promising HIV prevention tool to bridge the high-risk years of AYA between sexual debut and adulthood. OBJECTIVES: Concerns have been raised that the use of PrEP could lead to an increase in sexual risk behaviour and sexually transmitted infections in general and less condom use in particular among adolescents. METHODS: This study assesses condom use among South African adolescents enrolled on a demonstration PrEP study, called Pluspills, being conducted in Cape Town and Soweto. A questionnaire on sexual risk behaviour was administered at baseline and after 4, 8 and 12 weeks. Three different questions on condom use were asked at each visit. Unless all answers indicated condom use at all times, a participant was scored 'at risk'. McNemar's tests and a Cochran's Q test were used to investigate changes in condom use over time. RESULTS: We interviewed 148 adolescents (66% female) at baseline. Eighty-nine participants completed all visits. In this group, an increase in condom use was observed over the period of 12 weeks. Most participants who reported behavioural changes mentioned an increase in condom use. CONCLUSION: There was no sign of sexual risk compensation in the 12 weeks of the study. Observed increase in condom use can be explained by an increased awareness of personal HIV risk or by social desirability or recall biases. In future research, additional data including other biomarkers of unprotected sex and longer follow-up time would be useful to help understand the relationship between PrEP use, sexual risk perception and consequent behaviours, especially in adolescents.