Dressings made with polyurethanes have been found to exhibit good and varied biological properties that make them good candidates for this application. However, as has been seen, the wound-healing process is complex, which includes four different stages. So far, the design and evaluation of polyurethane for wound dressing has focused on achieving good properties (mechanical, physicochemical, and biological), but each of them separates from the others or even directed at only one of the stages of skin wound-healing. Therefore, the aim of this systematic review is to explore the applications of polyurethanes in wound dressings and to determine whether could be designed to cover more than one stage of skin wound-healing. The PRISMA guidelines were followed. The current research in this field does not consider each stage separately, and the design of polyurethane dressings is focused on covering all the stages of wound healing with a single material but is necessary to replace polyurethanes in short periods of time. Additionally, little emphasis is placed on the hemostasis stage and further characterization of polyurethanes is still needed to correlate mechanical and physicochemical properties with biological properties at each stage of the wound-healing. Current research demonstrates an effort to characterize the materials physiochemically and mechanically, but in terms of their biological properties, most of the literature is based on the performance of histological tests of explants morphologically probing the compromised tissues, which give an indication of the potential use of polyurethanes in the generation of wound-healing dressings.

The material design of vascular grafts is required for their application in the health sector. The use of polyurethanes (PUs) in vascular grafts intended for application in the body appears to be adequate due to the fact that native tissues have similar properties as PUs. However, the influence of chemical structure on the biomechanics of PUs remains poorly described. The use of constitutive models, together with numerical studies, is a powerful tool for evaluating the mechanical behavior of materials under specific physiological conditions. Therefore, the aim of this study was to assess the mechanical properties of different PU mixtures formed by polycaprolactone diol, polyethylene glycol, and pentaerythritol using uniaxial tensile, strain sweep, and multistep creep-recovery tests. Evaluations of the properties were also recorded after samples had been soaked in phosphate-buffer saline (PBS) to simulate physiological conditions. A hyperelastic model based on the Mooney–Rivlin strain density function was employed to model the performance of PUs under physiological pressure and geometry conditions. The results show that the inclusion of polyethylene glycol enhanced viscous flow, while polycaprolactone diol increased the elastic behavior. Furthermore, tensile tests revealed that hydration had an important effect on the softening phenomenon. Additionally, after the hydration of PUs, the ultimate strength was similar to those reported for other vascular conduits. Lastly, hyperelastic models revealed that the compliance of the PUs showed a cyclic behavior within the tested time and pressure conditions and is affected by the material composition. However, the compliance was not affected by the geometry of the materials. These tests demonstrate that the materials whose compositions are 5–90–5 and 46.3–46.3–7.5 could be employed in the designs of vascular grafts for medical applications since they present the largest value of compliance, ultimate strength, and elongation at break in the range of reported blood vessels, thus indicating their suitability. Moreover, the polyurethanes were revealed to undergo softening after hydration, which could reduce the risk of vascular trauma.

The human amniotic membrane (hAM) has been used as an implant to enhance the regenerative process and control inflammation in different diseases, given their structure, biocompatibility, presence of stem cells and multiple growth factors. The objective of this study was to generate a standardized protocol for obtaining, processing, and storing hAMs that guarantee the conservation of their structural and cellular characteristics as well as their mechanical properties, ensuring their ease of handling, sterility, and quality that allows their implementation for therapeutic purposes in the field of regenerative medicine. The hAMs were obtained from mothers with healthy, full-term, controlled pregnancies and by cesarean section. The hAMs were processed under sterile conditions, manually separated from the placenta and, subsequently, they were frozen in a solution of culture medium plus 50% v/v glycerol. The protocol allows obtaining sterile hAMs composed of both epithelium and stroma with adequate preservation of the amniotic cells. The glycerol’s impact on the mechanical properties may enhance the membrane’s adaptability and conformability to diverse wound surfaces, potentially improving the healing process. It is necessary to repeat microbiological, cell viability and mechanical studies at 6 and 12 months to ensure that long-term frozen conditions do not affect the quality of the hAMs.

Background: The human amniotic membrane (hAM) is widely used in tissue engineering due to its low immunogenicity and extracellular matrix (ECM) rich in structural proteins; in this context, decellularization aims to remove cellular components while preserving tissue integrity, and this study aimed to compare the effects of two enzymatic methods (trypsin and thermolysin). Methods: Human amniotic membranes obtained from placentas were divided into three groups: non-decellularized control, trypsin-treated, and thermolysin-treated. The membranes were treated with 0.25 trypsin-EDTA for 60 min at 37 °C, followed by incubation with Triton X-100 for 30 min at 37 °C, or with 125 µg/mL thermolysin for 9 min at 37 °C. Histological analysis with hematoxylin–eosin and semi-quantitative scoring assessed epithelial and stromal integrity, immunohistochemistry evaluated laminin α and fibronectin expression with quantitative image analysis, and uniaxial tensile testing measured mechanical properties; no preregistration numbers or animal models were reported. Results: Trypsin achieved more effective epithelial removal, whereas thermolysin caused greater stromal disruption; no statistically significant differences in laminin α or fibronectin expression were found among groups (p > 0.05), indicating preservation of key ECM components; both treatments reduced mechanical performance, with thermolysin decreasing early- and mid-path stiffness and trypsin reducing late-path stress and work density. Conclusion: Both enzymatic protocols preserved ECM composition but induced distinct structural and mechanical alterations, suggesting that method selection should balance efficient cell removal with preservation of structural and functional properties according to the intended application.

The human amniotic membrane has (hAM) been used as implants to enhance the regenerative process and control inflammation in different disease given their structure, biocompatibility, presence of stem cells and multiple growth factors. The objective of this study was to generate a standardized protocol for obtaining, processing, and storing hAMs that guarantees the conservation of structural and cellular characteristics as well as its mechanical properties, ensuring its ease of handling, sterility, and quality that allows its implementation for therapeutic purposes in the field of regenerative medicine. The hAMs were obtained from mothers with healthy, full-term, controlled pregnancies and by cesarean section. The hAMs were processed under sterile conditions, manually separated from the placenta and subsequently, they were frozen in a solution of culture medium plus 50% v/v glycerol. The protocol allows obtaining sterile hAMs composed of both epithelium and stroma with adequate preservation of the amniotic cells. The glycerol's impact on the mechanical properties may enhance the membrane's adaptability and conformability to diverse wound surfaces, potentially improving the healing process. It´s necessary to repeat the microbiological, cell viability and mechanical studies at 6 and 12 months to ensure that long-term frozen conditions do not affect the quality of the hAMs.