Tissue Glue-Based Sealing Patch for the in vivo Prevention of Iatrogenic Prelabor Preterm Rupture of Fetal Membranes.

INTRODUCTION: One of the main concerns for all fetal surgeries is the risk of preterm delivery due to the preterm prelabor rupture of the fetal membranes (iPPROM). Clinical approaches to seal fetal membrane (FM) defects are missing due to the lack of appropriate strategies to apply sealing biomaterials at the defect site. METHODS: Here, we test the performance of a previously developed strategy to seal FM defects with cyanoacrylate-based sealing patches in an ovine model up to 24 days after application. RESULTS: Patches sealed tightly the fetoscopy-induced FM defects and remained firmly attached to the defect over 10 days. At 10 days after treatment, 100% (13/13) of the patches were attached to the FMs, and 24 days after treatment 25% (1/4) of the patches placed in CO2 insufflation, and 33% (1/3) in NaCl infusion remained. However, all successfully applied patches (20/24) led to a watertight sealing at 10 or 24 days after treatment. Histological analysis indicated that cyanoacrylates induced a moderate immune response and disrupted the FM epithelium. CONCLUSION: Together, these data show the feasibility of minimally invasive sealing of FM defects by locally gathering tissue adhesive. Further development to combine this technology with refined tissue glues or healing-inducing materials holds great promise for future clinical translation.

In vivo Sealing of Fetoscopy-Induced Fetal Membrane Defects by Mussel Glue.

INTRODUCTION: The benefits of fetal surgery are impaired by the high incidence of iatrogenic preterm prelabor rupture of the fetal membranes (iPPROM), for which chorioamniotic separation has been suggested as a potential initiator. Despite the urgent need to prevent iPPROM by sealing the fetoscopic puncture site after intervention, no approach has been clinically translated. METHODS: A mussel-inspired biomimetic glue was tested in an ovine fetal membrane (FM) defect model. The gelation time of mussel glue (MG) was first optimized to make it technically compatible with fetal surgery. Then, the biomaterial was loaded in polytetrafluoroethylene-coated nitinol umbrella-shaped receptors and applied on ovine FM defects (N = 10) created with a 10 French trocar. Its sealing performance and tissue response were analyzed 10 days after implantation by amniotic fluid (AF) leakage and histological methods. RESULTS: All ewes and fetuses recovered well after the surgery, and 100% ewe survival and 91% fetal survival were observed at explantation. All implants were tight at explantation, and no AF leakage was observed in any of them. Histological analysis revealed a mild tissue response to the implanted glue. CONCLUSION: MG showed promising properties for the sealing of FM defects and thereby the prevention of preterm birth. Studies to analyze the long-term tissue response to the sealant should be performed.

Minimally Invasive Precise Application of Bioadhesives to Prevent IPPROM on a Pregnant Sheep Model.

INTRODUCTION: Iatrogenic preterm premature rupture of the membrane remains the Achille's heel of fetoscopy. The aim of this study was to show in vivo feasibility of fetal membrane (FM) defect sealing by the application of tissue glues with umbrella-shaped receptors. METHODS: First, we adapted our previously described ex vivo strategy and evaluated the adhesion strength of different tissue glues, Histoacryl® and Glubran2®, by bonding polytetrafluoroethylene or silicone encapsulated nitinol glue receptor to human FM. Then, we exposed pregnant sheep uterus through a laparotomy and placed a 10-French trocar into the amniotic cavity through which the umbrella-shaped glue receptor (n = 9) was inserted and fixated onto the FM with the tissue glues (n = 8). The tightness of the sealed defects was assessed 4 h post-surgery. RESULTS: Both tissue glues tested resulted in adhesion of the glue receptors to the FM ex vivo. In vivo, all glue receptors opened in the amniotic cavity (n = 9) and all successfully placed glue receptors sealed the FM defect (n = 8). Four hours post-surgery, 2 treatment sites showed minimal leakage whereas the negative control without glue (n = 1) showed substantial leakage. DISCUSSION: This in vivo study confirms that fetoscopically induced FM defects can be sealed by the application of tissue adhesives.

Minimally Invasive Surgical Device for Precise Application of Bioadhesives to Prevent iPPROM.

INTRODUCTION: The benefits of endoscopic fetal surgery are deteriorated by the high risk of iatrogenic preterm prelabor rupture of fetal membranes (iPPROM). While previous studies have reported good sealing candidates to prevent membrane rupture, the delivery of these materials to the location of membrane puncture remains unsolved. MATERIALS AND METHODS: We describe an approach to apply sealing materials onto the amnion through the fetoscopy port. We developed a device composed of an umbrella-shaped polyester coated nitinol mesh and an applicator. The spontaneously unfolding umbrella is pushed through the port, pulled against the amnion, and glued onto the amnion defect site. We tested the adhesion strength of multiple glues and tested the feasibility and reproducibility of this fetal membrane sealing approach in an ex vivo model. RESULTS: The umbrella unfolded and was well positioned in all tests (n = 18). When applied via the fetoscopy port, umbrellas were successfully glued onto the fetal membrane, and all of them completely covered the defect (n = 5). The mean time needed for the whole procedure was 3 min. DISCUSSION: This study is a proof of concept presenting a potential future solution for the precise local application of bioadhesives for the prevention of iPPROM.

Label-Free Quantification Proteomics for the Identification of Mesenchymal Stromal Cell Matrisome Inside 3D Poly(Ethylene Glycol) Hydrogels.

Cells modulate the functional properties of their environment by depositing extracellular matrix (ECM) proteins during biological processes in vivo and in vitro. Despite the ECMs central role in tissue formation, its quantification in hydrogels like Matrigel, which have a complex materials-inherent biopolymer composition is exceptionally challenging. Here, the use of protein-free, synthetic poly(ethylene glycol) hydrogels enables the analysis of deposited human bone marrow mesenchymal stromal cells ECM directly harvested from fresh 3D cell cultures by a tandem mass spectrometry (LC-MS/MS) method. In this study, it is proved that a label-free LC-MS/MS quantification method can selectively identify proteins deposited in 3D synthetic hydrogels following different growth factor (GF) treatments. Furthermore, it is shown that the sequence in which GFs are administered and the choice of stimuli significantly influences the number and abundance of ECM proteins. Therefore, this provides a versatile method to optimize GF treatments in synthetic hydrogel-based regenerative medicine and tissue engineering approaches.

Precision assembly of complex cellular microenvironments using holographic optical tweezers.

The accurate study of cellular microenvironments is limited by the lack of technologies that can manipulate cells in 3D at a sufficiently small length scale. The ability to build and manipulate multicellular microscopic structures will facilitate a more detailed understanding of cellular function in fields such as developmental and stem cell biology. We present a holographic optical tweezers based technology to accurately generate bespoke cellular micro-architectures. Using embryonic stem cells, 3D structures of varying geometries were created and stabilized using hydrogels and cell-cell adhesion methods. Control of chemical microenvironments was achieved by the temporal release of specific factors from polymer microparticles positioned within these constructs. Complex co-culture micro-environmental analogues were also generated to reproduce structures found within adult stem cell niches. The application of holographic optical tweezers-based micromanipulation will enable novel insights into biological microenvironments by allowing researchers to form complex architectures with sub-micron precision of cells, matrices and molecules.