Injectable silk-based biomaterials for cervical tissue augmentation: an in vitro study.

BACKGROUND: Cerclage therapy is an important treatment option for preterm birth prevention. Several patient populations benefit from cerclage therapy including patients with a classic history of cervical insufficiency; patients who present with advanced cervical dilation prior to viability; and patients with a history of preterm birth and cervical shortening. Although cerclage is an effective treatment option in some patients, it can be associated with limited efficacy and procedure complications. Development of an alternative to cerclage therapy would be an important clinical development. Here we report on an injectable, silk protein-based biomaterial for cervical tissue augmentation. The rationale for the development of an injectable biomaterial is to restore the native properties of cervical tissue. While cerclage provides support to the tissue, it does not address excessive tissue softening, which is a central feature of the pathogenesis of cervical insufficiency. Silk protein-based hydrogels, which are biocompatible and naturally degrade in vivo, are suggested as a platform for restoring the native properties of cervical tissue and improving cervical function. OBJECTIVE: We sought to study the properties of an injectable, silk-based biomaterial for potential use as an alternative treatment for cervical insufficiency. These biomaterials were evaluated for mechanical tunability, biocompatibility, facile injection, and in vitro degradation. STUDY DESIGN: Silk protein solutions were cross-linked by an enzyme catalyzed reaction to form elastic biomaterials. Biomaterials were formulated to match the native physical properties of cervical tissue during pregnancy. The cell compatibility of the materials was assessed in vitro using cervical fibroblasts, and biodegradation was evaluated using concentrated protease solution. Tissue augmentation or bulking was demonstrated using human cervical tissue from nonpregnant hysterectomy specimens. Mechanical compression tests measured the tissue stiffness as a function of the volume of injected biomaterial. RESULTS: Silk protein concentration, molecular weight, and concentration of cross-linking agent were varied to generate biomaterials that functioned from hard gels to viscous fluids. Biomaterials that matched the mechanical features of cervical tissues were chosen for further study. Cervical fibroblasts cultured on these biomaterials were proliferative and metabolically active over 6 days. Biomaterials were degraded in protease solution, with rate of mass loss dependent on silk protein molecular weight. Injection of cervical tissue samples with 100 µL of the biomaterial resulted in a significant volume increase (22.6% ± 8.8%, P < .001) with no significant change in tissue stiffness. CONCLUSION: Cytocompatible, enzyme cross-linked silk protein biomaterials show promise as a tissue bulking agent. The biomaterials were formulated to match the native mechanical properties of human cervical tissue. These biomaterials should be explored further as a possible alternative to cerclage for providing support to the cervix during pregnancy.

Prenatal aneuploidy screening in a low-risk Hispanic population: price elasticity and cost-effectiveness.

BACKGROUND: In October 2015, the Massachusetts Medicaid program temporarily stopped reimbursement for procedures in which the International Classification of Diseases, Tenth Edition, code for serum aneuploidy screening used by certain communities was stipulated. This change led to a substantial number of patients who went without aneuploidy screening for approximately 3 years. OBJECTIVE: This study aimed to determine the change in use and cost-effectiveness of prenatal aneuploidy serum screening in a low-risk Hispanic Medicaid population in Massachusetts. STUDY DESIGN: We conducted a retrospective chart review of Spanish-speaking pregnant patients younger than 35 years of age who underwent aneuploidy serum screening at a Massachusetts community health center. The study compared the aneuploidy serum screening rates for the periods before and after May 2016 when the Massachusetts Medicaid program, MassHealth, temporarily discontinued reimbursement for the screening. Based on these rates, we developed a Markov cohort simulation model to assess the economic value of reimbursed aneuploidy screening vs nonreimbursed or limited screening. Clinical outcomes included trisomy 21, live births, and therapeutic abortions for a trisomy 21 diagnosis. Economic outcomes included discounted quality-adjusted life years and lifetime medical costs, net health benefit, and incremental cost-effectiveness ratios. RESULTS: Before the MassHealth policy change, 69% (55/80) of pregnant individuals selected quad or sequential screens in comparison with only 9% (10/112) who selected screens after the policy change. Traditional aneuploidy serum screening in a low-risk (aged <35 years) Hispanic population was considered to be cost-saving (ie, led to lower incremental costs and higher incremental benefits when compared with nonreimbursed or limited screening). CONCLUSION: From a United States healthcare payer perspective, aneuploidy serum screening for Hispanic pregnant individuals under 35 years of age is economically advantageous when compared with limited screening.

Uterus and cervix anatomical changes and cervix stiffness evolution throughout pregnancy.

The coordinated biomechanical performance, such as uterine stretch and cervical barrier function, within maternal reproductive tissues facilitates healthy human pregnancy and birth. Quantifying normal biomechanical function and detecting potentially detrimental biomechanical dysfunction (e.g., cervical insufficiency, uterine overdistention, premature rupture of membranes) is difficult, largely due to minimal data on the shape and size of maternal anatomy and material properties of tissue across gestation. This study quantitates key structural features of human pregnancy to fill this knowledge gap and facilitate three-dimensional modeling for biomechanical pregnancy simulations to deeply explore pregnancy and childbirth. These measurements include the longitudinal assessment of uterine and cervical dimensions, fetal weight, and cervical stiffness in 47 low-risk pregnancies at four time points during gestation (late first, middle second, late second, and middle third trimesters). The uterine and cervical size were measured via 2-dimensional ultrasound, and cervical stiffness was measured via cervical aspiration. Trends in uterine and cervical measurements were assessed as time-course slopes across pregnancy and between gestational time points, accounting for specific participants. Patient-specific computational solid models of the uterus and cervix, generated from the ultrasonic measurements, were used to estimate deformed uterocervical volume. Results show that for this low-risk cohort, the uterus grows fastest in the inferior-superior direction from the late first to middle second trimester and fastest in the anterior-posterior and left-right direction between the middle and late second trimester. Contemporaneously, the cervix softens and shortens. It softens fastest from the late first to the middle second trimester and shortens fastest between the late second and middle third trimester. Alongside the fetal weight estimated from ultrasonic measurements, this work presents holistic maternal and fetal patient-specific biomechanical measurements across gestation.

Ferroportin expression and regulation in human placenta/fetal membranes: Implications for ferroptosis and adverse pregnancy outcomes.

Iron overload is associated with pregnancy complications. Ferroportin (FPN) is the only known iron exporter in mammalian cells. We hypothesize that FPN is functionally important in ferrotopsis, a process of iron-dependent non-apoptotic programmed cell death, and may have a critical role to play in pregnancy success. We investigated the expression of FPN in placenta/fetal membranes by immunohistochemistry in tissues collected from pregnancies with/without preeclampsia (PE) and spontaneous preterm birth (SPTB). FPN was highly expressed in both trophoblasts and decidual cells found in placenta/fetal membranes. Staining was significantly reduced in fetal membranes from SPTB versus healthy pregnancies (P = 0.046). FPN expression in immortalized human endometrial stromal cells (HESC) increased with in vitro decidualization induction using 1 µM of medroxyprogesterone acetate and 0.5 mM of dibutyryl-cAMP. In addition, both HESC cells and immortalized extravillous trophoblast SW71 cells with FPN knockdown showed significant sensitivity to ferroptosis inducer, erastin (P < 0.001 and P = 0.009, respectively). The survival of both HESC and SW71 cells was not negatively affected by iron supplementation with ferric ammonium citrate in the medium. However, SW71 cells were more sensitive than HESC cells to physiologic iron in the presence of a non-lethal dose of erastin (P < 0.001). Taken together, our data demonstrating increased sensitivity of FPN knockdown HESC and SW71 cells to erastin and increased sensitivity of trophoblasts to iron overload under ferroptotic stress support the hypothesis that FPN protects against ferroptosis during pregnancy.

Measurement of fetal heart rate variability on an electronic monitor using a prototype electronic ruler.

OBJECTIVE: To develop a prototype electronic ruler for assessment of fetal heart rate (FHR) variability on an electronic monitor and test its reliability and accuracy. STUDY DESIGN: A prototype electronic ruler was designed and developed for assessment of FHR variability on electronic monitors. The electronic ruler consisted of horizontal bands that were sized and colored to embed the four FHR variability categories. The reliability and accuracy of using the electronic ruler to assess FHR variability was studied with expert clinicians. RESULTS: Intrarater and interrater reliability was moderate for both the electronic ruler and paper strips. The amplitude measurement accuracy of expert variability assessment compared with a gold standard was significantly improved (p < 0.001) with the electronic ruler versus paper strips. The accuracy of subjects' FHR variability category responses compared with the gold standard revealed no significant difference (p = 0.50) using either display type. CONCLUSION: Performance of the electronic ruler was equivalent to paper strips, which may aid assessment of variability on electronic monitors as paper strips become less prevalent.

Tissue Engineering for Cervical Function in Pregnancy.

Cervical insufficiency is a significant obstetrical complication that causes preterm birth. The current treatment of cervical insufficiency is cerclage surgery. A cerclage is a suture that is placed around the cervix to provide compression support. The load bearing portion of the cervix is the stroma, which is composed of collagen-rich extracellular matrix. A remarkable feature of the cervix is progressive softening throughout gestation. The biochemical mechanisms of cervical softening, however, are poorly understood. In this narrative review, we discuss our approach to using tissue engineering techniques to study cervical function in pregnancy. A brief review of the clinical significance of the cervix in pregnancy is presented. The development of a tissue engineering model for studying cervical remodeling is discussed. We also discuss an engineered injectable hydrogel as an alternate treatment for cervical dysfunction. We advocate for a bioengineering approach to study cervical dysfunction in pregnancy.

Randomized controlled trial of single-use negative-pressure wound therapy dressings in morbidly obese patients undergoing cesarean delivery.

BACKGROUND: The single-use negative-pressure wound therapy dressings are designed to use over a closed surgical wound. Early prospective studies suggested that these dressings may be of potential benefit in reducing cesarean wound complications. OBJECTIVE: This study aimed to test the hypothesis that incisional negative-pressure wound therapy decreases postoperative wound morbidity compared with standard surgical dressing in patients with class III obesity undergoing cesarean delivery. STUDY DESIGN: In a single-site, parallel, randomized controlled trial, participants with class III obesity (body mass index ≥40 kg/m2) were recruited to participate in the study. Patients were consented in the ambulatory obstetrical units, on admission to the antepartum service, and on labor and delivery before active labor. Patients who had a cesarean delivery were randomized to either the standard surgical dressing or a prophylactic negative-pressure wound therapy device. The randomization was achieved using permuted blocks of 4, 6, and 8 in a 1:1 allocation ratio. The primary outcome was a composite outcome of wound complications. The planned enrollment of 242 subjects was based on the power to detect a 50% decrease in the composite wound outcome, assuming a 30% baseline wound morbidity rate for this population. The outcomes were assessed by study staff blinded to the patient's treatment arm. RESULTS: An unplanned interim analysis was performed because of the slow enrollment and publication of larger trials showing no benefit of the negative-pressure wound therapy. Of 411 eligible patients during the study period, 212 participants with class III obesity were enrolled. Of these, 110 underwent cesarean delivery and were subsequently randomized (55 to standard dressing and 55 to prophylactic negative-pressure wound therapy device). The primary outcome occurred in 29.1% in the standard surgical dressing compared with 20% in the negative-pressure wound therapy group (risk difference, 9.1%; 95% confidence interval, -8.3 to 25.8%; P=.38). The study was stopped early because of a low enrollment rate and lower likelihood of seeing a clinically significant benefit. CONCLUSION: The trial was stopped after an unplanned, interim analysis showed the use of a prophylactic negative-pressure wound therapy device used for cesarean delivery did not reduce wound complications compared with a standard surgical dressing.

Cervical Augmentation with an Injectable Silk-Based Gel: Biocompatibility in a Rat Model of Pregnancy.

The aim of this study was to study the biocompatibility of an injectable silk gel in the cervix in a rat model of pregnancy. The rationale is to study an injectable gel as an alternate treatment for cervical insufficiency. We further aimed to perform cervical injections via a vaginal route to mimic the clinical procedure of a cervical cerclage. We performed an in vivo study in pregnant female Sprague Dawley rats. Cervical procedures were performed using a customized speculum under general anesthesia. Injections were performed on gestational day 16. The responses to silk gel injections were compared to polyethylene terephthalate suture and saline controls on gestational day 19 and postpartum. The inflammatory response was evaluated by histology, PCR for inflammatory gene expression, and ELISA for protein levels of proinflammatory mediators. Silk gel injections were performed on 13 animals. All animals tolerated the procedure. Silk gel occupied 5% of the stroma after injection. Injected silk gel caused neither preterm birth nor prolonged pregnancy and had no effect on the kits. When comparing inflammatory responses, expression of inflammatory genes and proinflammatory proteins in the silk gel group was intermediate between saline (lowest) and cerclage suture (highest). Injectable silk gel was more inflammatory compared to saline injections but less inflammatory compared to the suture material used for cervical cerclage. This study is an important step toward development of an alternative treatment for cervical insufficiency.

Ex vivo pregnant-like tissue model to assess injectable hydrogel for preterm birth prevention.

Cervical insufficiency (CI) is an important cause of preterm birth, which leads to severe newborn complications. Standard treatment for CI is cerclage, which has variable success rates, resulting in a clinical need for alternative treatments. Our objective was to develop an ex vivo model of softened cervical tissue to study an injectable silk-based hydrogel as a novel alternative treatment for CI. Cervical tissue from nonpregnant women was enzymatically treated and characterized to determine tissue hydration, collagen organization, and mechanical properties via unconfined compression. Enzymatic treatment led to an 86 ± 7.9% decrease in modulus, which correlated to a decrease in collagen organization as observed by differences in collagen birefringence. The softened tissue was injected with a crosslinked silk-hyaluronic acid composite hydrogel. After injection, the mechanical properties and volume increase of the hydrogel-treated tissue were measured resulting in a 54 ± 16% volume increase with minimal effect on tissue mechanical properties. In addition, cervical fibroblasts on silk-hyaluronic acid hydrogels remained viable and exhibited increased proliferation and metabolic activity over 5 days. Overall, this study developed an ex vivo pregnant-like human tissue model to assess cervical augmentation and showed the potential of silk-based hydrogels as an alternative treatment for cervical insufficiency.

Prevention of preterm birth: Novel interventions for the cervix.

Preterm birth is the leading cause of neonatal mortality and morbidity worldwide. Spontaneous preterm birth is a complex, multifactorial condition in which cervical dysfunction plays an important role in some women. Current treatment options for cervical dysfunction include cerclage and supplemental progesterone. In addition, cervical pessary is being studied in research protocols. However, cerclage, supplemental progesterone and cervical pessary have well known limitations and there is a strong need for alternate treatment options. In this review, we discuss two novel interventions to treat cervical dysfunction: (1) injectable, silk protein-based biomaterials for cervical tissue augmentation (injectable cerclage) and (2) a patient-specific pessary. Three-dimensional computer simulation of the cervix is performed to provide a biomechanical rationale for the interventions. Further development of these novel interventions could lead to new treatment options for women with cervical dysfunction.

Silk-based injectable biomaterial as an alternative to cervical cerclage: an in vitro study.

OBJECTIVE: New therapies to prevent preterm birth are needed. Our objective was to study an injectable biomaterial for human cervical tissue as an alternative to cervical cerclage. STUDY DESIGN: Human cervical tissue specimens were obtained from premenopausal gynecological hysterectomies for benign indications. A 3-part biomaterial was formulated, consisting of silk protein solution blended with a 2-part polyethylene glycol gelation system. The solutions were injected into cervical tissue and the tissue was evaluated for mechanical properties, swelling, cytocompatibility, and histology. RESULTS: The stiffness of cervical tissue more than doubled after injection (P = .02). Swelling properties of injected tissue were no different than native tissue controls. Cervical fibroblasts remained viable for at least 48 hours when cultured on the biomaterial. CONCLUSIONS: We report a silk-based, biocompatible, injectable biomaterial that increased the stiffness of cervical tissue compared to uninjected controls. Animal studies are needed to assess this biomaterial in vivo.

A GBS culture collected shortly after GBS prophylaxis may be inaccurate.

OBJECTIVE: To determine whether a vaginal-rectal culture obtained after antibiotic therapy has begun accurately detects pre-existing colonization with group B streptococcus (GBS). METHODS: A prospective cohort study of women presenting at in labor who were known to be colonized with GBS were recruited. A GBS culture was obtained prior to administration of intravenous penicillin prophylaxis and repeated 2 hours following the first dose of penicillin. The two results were compared. RESULTS: Eighty subjects were recruited. Complete results were obtained for 61 (76 %) subjects. Of these, 47 (77 %) had a GBS positive on initial culture. Persistence of GBS 2 hours after antibiotic exposure was seen in 30/47 (64 %). Conversion from GBS positive to GBS negative status was seen in 17/47 (36%). CONCLUSIONS: A vaginal-rectal culture for GBS performed after antibiotic prophylaxis has commenced may not accurately reflect a patient's GBS colonization status.