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Sample histology. Representative histological sections show the progression of engineered skin substitute (ESS) remodeling from (a) an acellular collagenglycosaminoglycan sponge (CGS), (b) dermal skin substitute (DSS) cultured in vitro two weeks, (c) ESS cultured in vitro two weeks, (d) grafted ESS six weeks post implantation on athymic mice, and compared to (e) mouse autograft, and (f) native mouse skin. Scale bar 5 0.5 mm.
Source publication
Engineered skin substitutes (ESS) have been reported to close full-thickness burn wounds, but are subject to loss from mechanical shear due to their deficiencies in tensile strength and elasticity. Hypothetically, if the mechanical properties of ESS matched those of native skin, losses due to shear or fracture could be reduced. To consider modifica...
Contexts in source publication
Context 1
... Construct remodeling was assessed primarily from histological sections (Fig. 2) and from other gross measure- ments and observations as described below. CGS were porous and variable in thickness (335 6 97 lm). The addition of fibroblasts to CGS resulted in rapid reduction in sponge surface area by 20% 6 6% within the first 24 h of culture. After two weeks the surface area of the DSS continued to decrease to 33.6% ...
Context 2
... (52% 6 4%) and an increase in thickness (595 6 27 lm). SEC measurements on ESS at 7 and 13 days (755 6 7 DPM and 10 6 6 DPM, respectively) indicated that an epidermal barrier had begun to form. By comparison, SEC measurements on DSS did not change between days 7 and 13 (843 6 2 DPM and 855 6 8 DPM, respectively). Photomicro- graphs at day 14 ( Fig. 2) confirmed that an epidermal-dermal anat- omy had formed. These images show a cornified layer that was separated from a fibroblast remodeled dermal component by a stratified and nucleated ...
Citations
... Prior to testing, skin was prepared by cleaning the epidermis and carefully resecting the hypodermis. As in previous studies, traditional dogbone shapes with a 7.11 mm × 2.03 mm gauge region were cut from the tissue using a punch, and fiduciary dots were marked on the tissue using a fine-tipped pen [33]. The tissue was then placed into a mechanical tester (ADMET; Norwood, MA) integrated with a multiphoton microscope (Bruker; Billerica, MA) equipped with a wide-field camera (Lumenera; Ottawa, ON), enabling 3D micro-scale and 2D macro-scale imaging of the tissue during mechanical testing [23]. ...
The mechanical properties of skin change during aging but the relationships between structure and mechanical function remain poorly understood. Previous work has shown that young skin exhibits a substantial decrease in tissue volume, a large macro-scale Poisson’s ratio, and an increase in micro-scale collagen fiber alignment during mechanical stretch. In this study, label-free multiphoton microscopy was used to quantify how the microstructure and fiber kinematics of aged mouse skin affect its mechanical function. In an unloaded state, aged skin was found to have less collagen alignment and more non-enzymatic collagen fiber crosslinks. Skin samples were then loaded in uniaxial tension and aged skin exhibited a lower mechanical stiffness compared to young skin. Aged tissue also demonstrated less volume reduction and a lower macro-scale Poisson’s ratio at 10% uniaxial strain, but not at 20% strain. The magnitude of 3D fiber realignment in the direction of loading was not different between age groups, and the amount of realignment in young and aged skin was less than expected based on theoretical fiber kinematics affine to the local deformation. These findings provide key insights on how the collagen fiber microstructure changes with age, and how those changes affect the mechanical function of skin, findings which may help guide wound healing or anti-aging treatments.
... Specifically, it was observed that the average diameter of CIP-IVM, CIP, and IVM NF ranges from 225 to 295 nm (Fig. 1C), while PVA showed 405 nm. The mechanical strength of human skin including ultimate tensile strength (UTS) ranges approximately 1-40 MPa [36,37] (Fig. 1B). The CIP-IVM NF evaluated in this study were in between the skin tensile strength ranges and are suitable for wound dressing. ...
... [13][14][15] To date, an ideal, fully functional dermal substitute has not yet been developed. [16][17][18][19] To overcome these challenges, researchers have explored alternative approaches to scaffold-based dermal regeneration. One promising approach is the development of a self-assembled, cell-based dermal substitute from human fibroblasts using three-dimensional (3D) culture. ...
Skin substitutes have emerged as an alternative to autografts for the treatment of skin defects. Among them, scaffold-based dermal substitutes have been extensively studied; however, they do have certain limitations, such as delayed vascularization, limited elasticity, and the inability to achieve permanent engraftment. Self-assembled, cell-based dermal substitutes are a promising alternative that may overcome these shortcomings but have not yet been developed. In this study, we successfully developed a cell-based dermal substitute (cultured dermis) through the long-term culture of human dermal fibroblasts using the net-mold method, which enables three-dimensional (3D) cell culture without the use of a scaffold. Spheroids prepared from human dermal fibroblasts were poured into a net-shaped mold and cultured for 2, 4, or 6 months. The dry weight, tensile strength, collagen and glycosaminoglycan levels, and cell proliferation capacity were assessed and compared among the 2-, 4-, and 6-month culture periods. We found that collagen and glycosaminoglycan levels decreased over time, while the dry weight remained unchanged. Tensile strength increased at 4 months, suggesting that remodeling had progressed. Additionally, the cell proliferation capacity was maintained, even after a 6-month culture period. Unexpectedly, the internal part of the cultured dermis became fragile, resulting in the division of the cultured dermis into two collagen-rich tissues, each of which had a thickness of 400 μm and sufficient strength to be sutured during in vivo analysis. The divided 4-month cultured dermis was transplanted to skin defects of immunocompromised mice and its wound healing effects were compared to those of a clinically available collagen-based artificial dermis. The cultured dermis promoted epithelialization and angiogenesis more effectively than the collagen-based artificial dermis. Although further improvements are needed, such as the shortening of the culture period and increasing the size of the cultured dermis, we believe that the cultured dermis presented in this study has the potential to be an innovative material for permanent skin coverage.
... To fabricate an effective drug delivery system with optimal antibacterial activity and no cytotoxicity, three different concentrations of AMP were loaded into a DPS scaffold to optimize the antibacterial property of the AMP-loaded DPS against ATCC 19606 and XDR clinical isolates. The mechanical characteristic of the scaffolds is believed to be an important consideration when dealing with skin tissue engineering (Sander et al. 2014). In this context, the tensile strength, elongation at break, and young modulus of DPS-loaded AMP were slightly higher than DPS, but the difference was not significant. ...
Post-wound infections have remained a serious threat to society and healthcare worldwide. Attempts are still being made to develop an ideal antibacterial wound dressing with high wound-healing potential and strong antibacterial activity against extensively drug-resistant bacteria (XDR). In this study, a biological-based sponge was made from decellularized human placenta (DPS) and then loaded with different concentrations (0, 16 µg/mL, 32 µg/mL, 64 µg/mL) of an antimicrobial peptide (AMP, CM11) to optimize an ideal antibacterial wound dressing. The decellularization of DPS was confirmed by histological evaluations and DNA content assay. The DPS loaded with different contents of antimicrobial peptides (AMPs) showed uniform morphology under a scanning electron microscope (SEM) and cytobiocompatibility for human adipose tissue-derived mesenchymal stem cells. Antibacterial assays indicated that the DPS/AMPs had antibacterial behavior against both standard strain and XDR Acinetobacter baumannii in a dose-dependent manner, as DPS loaded with 64 µg/mL showed the highest bacterial growth inhibition zone and elimination of bacteria under SEM than DPS alone and DPS loaded with 16 µg/mL and 32 µg/mL AMP concentrations. The subcutaneous implantation of all constructs in the animal model demonstrated no sign of acute immune system reaction and graft rejection, indicating in vivo biocompatibility of the scaffolds. Our findings suggest the DPS loaded with 64 µg/mL as an excellent antibacterial skin substitute, and now promises to proceed with pre-clinical and clinical investigations.
... Immediately after cutting, we clamped the sample at its shoulder region of both ends using custom stainless-steel grips and mounted the setup onto a universal testing machine with a 10-N load cell (Instron Inc., Norwood, MA; accuracy of 0.01 N). We performed a two-part uniaxial tensile test following the protocol in a previous study (58). The first part is a 10-round cyclic test as preconditioning to provide the samples with a consistent loading history, where the sample was extended to a 10% peak strain in each cycle. ...
Despite the advancements in skin bioengineering, 3D skin constructs are still produced as flat tissues with open edges, disregarding the fully enclosed geometry of human skin. Therefore, they do not effectively cover anatomically complex body sites, e.g., hands. Here, we challenge the prevailing paradigm by engineering the skin as a fully enclosed 3D tissue that can be shaped after a body part and seamlessly transplanted as a biological clothing. Our wearable edgeless skin constructs (WESCs) show enhanced dermal extracellular matrix (ECM) deposition and mechanical properties compared to conventional constructs. WESCs display region-specific cell/ECM alignment, as well as physiologic anisotropic mechanical properties. WESCs replace the skin in full-thickness wounds of challenging body sites (e.g., mouse hindlimbs) with minimal suturing and shorter surgery time. This study provides a compelling technology that may substantially improve wound care and suggests that the recapitulation of the tissue macroanatomy can lead to enhanced biological function.
... Furthermore, the nanofiber diameter changes alter the polymer chain orientation and affect the mechanical properties of nanofibers [44]. Taken together, as the tensile strength of normal skin is between 1 and 40 MPa [45], the mechanical properties obtained from both CS/PVA and CS/PVA/ABs confirmed that our constructs are suitable for skin wound dressing applications. ...
Resistance of bacterial pathogens to conventional antibiotics has remained a significant challenge in managing post-wound infections, especially in developing countries. Here, a nanofibrous chitosan/poly (vinyl alcohol) (CS/PVA) mat was designed for controlled delivery of three different concentrations of two antibiotics (colistin/meropenem ratio of 32/64 μg/ml (AB1), 64/128 μg/ml (AB2), and 128/256 (AB3) μg/ml) with synergistic antibacterial activity against ATCC and extensively drug-resistant (XDR) Acinetobacter baumannii clinical isolates. The scaffolds showed a uniform fibrous structure with no bead formation with a sustained release of the antibiotics for one week. The elongation at break, wettability, porosity, and average fiber diameter decreased with increased antibiotics concentrations. Young's modulus and tensile strength showed a significant increase after adding antibiotics. All the constructs showed excellent in vitro cytocompatibility for fibroblasts and biocompatibility in an animal model. The antibacterial assays confirmed the dose-dependent antibacterial activity of the CS/PVA. The scaffolds loaded with AB2 and AB3 showed biocidal properties against ATCC, while only CS/PVA/AB3 had antibacterial activity against XDR clinical isolates. This study suggests the CS/PVA/AB3 nanofibrous scaffold contained 128/256 μg/ml colistin/meropenem as an excellent antibacterial wound dressing for protection of skin wounds from XDR clinical isolates and now promises to proceed with pre-clinical investigations.
... To fabricate an effective drug delivery system with optimal antibacterial activity and no cytotoxicity, three different concentrations of AMP were loaded into a DPS scaffold to optimize the antibacterial property of the AMP-loaded DPS against ATCC and XDR clinical isolates. The mechanical characteristic of the scaffolds is believed to be an important consideration when dealing with skin tissue engineering (Sander et al., 2014). In this context, the tensile strength, elongation at break, and young modulus, of DPS loaded-AMP were slightly higher than DPS, but the difference was not signi cant. ...
Post-wound infections have remained a serious threat to society and healthcare worldwide. Attempts are still being made to develop an ideal antibacterial wound dressing with high wound healing potential and strong antibacterial activity against extensively drug-resistant bacteria (XDR). In this study, a biological-based sponge was made from decellularized human placenta (DPS), then loaded with different concentrations (0, 16 µg/mL, 32 µg/mL, 64µg/mL) of an antimicrobial peptide (AMP, CM11) to optimize an ideal antibacterial wound dressing. The decellularization of DPS was confirmed by histological evaluations and DNA content assay. The DPS loaded with different contents of antimicrobial peptides (AMPs) showed uniform morphology under a scanning electron microscope (SEM) and cytobiocompatibility for human adipose tissue-derived mesenchymal stem cells. Antibacterial assays indicated that the DPS/AMPs had antibacterial behavior against both standard strain and XDR Acinetobacter baumannii in a dose-dependent manner, as DPS loaded with 64µg/mL showed the highest bacterial growth inhibition zone and elimination of bacteria under SEM than DPS alone and DPS loaded with 16 µg/mL, 32 µg/mL AMP concentrations. The subcutaneous implantation of all constructs in the animal model demonstrated no sign of acute immune system reaction and graft rejection, indicating in vivo biocompatibility of the scaffolds. Our findings suggest the DPS loaded with 64 µg/mL as an excellent antibacterial skin substitute, and now promises to proceed with pre-clinical and clinical investigations.
... Therefore, FTIR conrmed the blend of PLA, PVP and Aloin. 35 which is similar to the tensile strength of our wound dressings. Fig. 4(A) shows a sandwich structure with a three-layer structure, which shows staged mechanical strength and exibility. ...
We have prepared a new type of Aloin/Polyvinylpyrrolidone (PVP)-Aloin/PVP/polylactic acid (PLA)-PLA sandwich nanofiber membrane (APP), to achieve a time-regulated biphasic drug release behavior, used for hemostasis, antibacterial activity and accelerated wound healing. We tested the water absorption capacity, water contact angle, tensile strength, thermogravimetric analysis, Fourier transform infrared spectroscopy and in vitro drug release of the prepared material, as well as analyzed the morphology of the nanofiber membrane with a scanning electron microscope. In the wound healing experiment, the wound healing rate of APP on the 15th day was 96.67%, and it demonstrated excellent antibacterial activity by the disc diffusion method, showing superior antibacterial activity against Gram-negative bacteria. The skin defect model on the back of mice showed that APP nanofibers significantly induced granulation tissue growth, collagen deposition and epithelial tissue remodeling. Current research shows that the prepared composite nanofibers can quickly stop bleeding and can effectively promote wound healing.
... Selain itu, dilakukan karakterisasi terkait dengan kekuatan daya tarik pada nanofiber dengan melakukan uji tarik terhadap nanofiber. Berdasarkan hasil studi literatur, seluruh formula memenuhi kriteria kekuatan daya tarik yaitu pada rentang 1 -25 Mpa dimana hasil tersebut telah sesuai dengan nilai kekuatan daya tarik pada kulit manusia yaitu 1 -40 Mpa (Sander, et al. 2013). ...
Wound healing is a multifactorial process whose healing process can be done traditionally. However, its healing takes a long time so it is less effective. So the researchers conducted research related to new medical engineering for wound healing, namely tissue engineering using collagen. Collagen has a large particle size so it is necessary to reduce the size of the particle to increase its effectiveness, namely with nanofibers. To validate the wound healing effect on collagen nanofibers, a study based on literature review was carried out through library searches at reputable publishers such as Science Direct, Pubmed, Research gate, NBCI, Taylor & Francis, Hindawi, Spinger – Verlag, and Google Scholar by taking into account the inclusion and exclusion criteria. The results of the literature search show: 1. The formula used for the manufacture of collagen nanofibers is HFIP as a solvent for collagen and other additives that support the formation of nanofibers. 2. The method used for the manufacture of collagen nanofibers is electrospinning. 3. Good nanofibers are nanofibers that are smooth, dense, have a diameter of 100-500 nm and an tensile strength of 1-40 Mpa. 4. Collagen nanofibers have been shown to have good effectiveness in wound healing, which is indicated by an increase in average wound closure of up to 64% on day 7 and an average wound closure of up to 79% on day 14 in in vivo animal testing. Abstrak. Penyembuhan luka merupakan suatu proses multifaktorial yang proses penyembuhan nya dapat dilakukan secara tradisional. Namun, penyembuhan nya membutuhkan waktu yang cukup lama sehingga kurang efektif. Sehingga peneliti melakukan penelitian terkait dengan rekayasa medis baru untuk penyembuhan luka yaitu rekayasa jaringan dengan menggunakan kolagen. Kolagen mempunyai ukuran partikel yang besar sehingga diperlukan pengecilan ukuran partikel untuk meningkatkan efektivitasnya yaitu dengan nanofiber.Untuk memvalidasi adanya efek penyembuhan luka pada nanofiber kolagen dilakukan penelitian berbasis study literature review melalui penelusuran pustaka pada penerbit bereputasi seperti Science Direct, Pubmed, Research gate, NBCI, Taylor&Francis, Hindawi, Spinger – verlag, serta google scholar dengan memperhatikan kriteria inklusi dan eksklusi. Hasil penelusuran pustaka menunjukkan: 1. Formula yang digunakan untuk pembuatan nanofiber kolagen yaitu HFIP sebagai pelarut kolagen dan bahan tambahan lain yang menunjang pembentukan nanofiber. 2. Metode yang digunakan untuk pembuatan nanofiber kolagen yaitu electrospinning. 3. Nanofiber yang baik yaitu nanofiber yang halus, padat, memiliki diameter 100 – 500 nm serta kekuatan daya tarik 1 – 40 Mpa. 4. Nanofiber kolagen terbukti memiliki efektivitas yang baik dalam menyembuhkan luka yang ditandai dengan adanya peningkatan penutupan luka rata – rata hingga 64% pada hari ke 7 dan penutupan luka rata – rata hingga 79% pada hari ke 14 pada pengujian terhadap hewan secara in vivo.
... 26 Even the graded stiffness of biomaterials plays a very important role in cell migration and directing cellular responses in terms of chemical, physical, and biological signals. [27][28][29] Therefore, it becomes imperative that computational models are also able to predict the stiffness of bioprinted constructs before their application, which can provide a vital indication of the physicochemical and biological behavior of constructs postfabrication. ...
Extrusion-based bioprinting is an enabling biofabrication technique that is used to create heterogeneous tissue constructs according to patient-specific geometries and compositions. The optimization of bioinks as per requirements for specific tissue applications is an essential exercise in ensuring clinical translation of the bioprinting technologies. Most notably, optimum hydrogel polymer concentrations are required to ensure adequate mechanical properties of bioprinted constructs without causing significant shear stresses on cells. However, experimental iterations are often tedious for optimizing the bioink properties. In this work, a nonlinear finite element modeling approach has been undertaken to determine the effect of different bioink parameters such as composition, concentration on the range of stresses being experienced by the cells in the bioprinted construct. The stress distribution of the cells at different parts of the constructs has also been modeled. It is found that both bioink chemical compositions and concentrations can substantially alter the stress effects experienced by the cells. Concentrated regions of softer cells near pore regions were found to increase stress concentrations by almost three times compared with stress generated in cells away from the pores. The study provides a method for rapid optimization of bioinks, design of bioprinted constructs, as well as toolpath plans for fabricating constructs with homogenous properties.
