Re-epithelialization: advancing epithelium frontier during wound healing

The first function of the skin is to serve as a protective barrier against the environment. Its loss of integrity as a result of injury or illness may lead to a major disability and the first goal of healing is wound closure involving many biological processes for repair and tissue regeneration. In vivo wound healing has four phases, one of them being the migration of the healthy epithelium surrounding the wound in the direction of the injury in order to cover it. Here, we present a theoretical model of the re-epithelialization phase driven by chemotaxis for a circular wound. This model takes into account the diffusion of chemoattractants both in the wound and the neighbouring tissue, the uptake of these molecules by the surface receptors of epithelial cells, the migration of the neighbour epithelium, the tension and proliferation at the wound border. Using a simple Darcy''s law for cell migration transforms our biological model into a free-boundary problem, which is analysed in the simplified circular geometry leading to explicit solutions for the closure and making stability analysis possible. It turns out that for realistic wound sizes of the order of centimetres and from experimental data, the re-epithelialization is always an unstable process and the perfect circle cannot be observed, a result confirmed by fully nonlinear simulations and in agreement with experimental observations.     

Simulation of lung alveolar epithelial wound healing in vitro

The mechanisms that enable and regulate alveolar type II (AT II) epithelial cell wound healing in vitro and in vivo remain largely unknown and need further elucidation. We used an in silico AT II cell-mimetic analogue to explore and better understand plausible wound healing mechanisms for two conditions: cyst repair in three-dimensional cultures and monolayer wound healing. Starting with the analogue that validated for key features of AT II cystogenesis in vitro, we devised an additional cell rearrangement action enabling cyst repair. Monolayer repair was enabled by providing ‘cells’ a control mechanism to switch automatically to a repair mode in the presence of a distress signal. In cyst wound simulations, the revised analogue closed wounds by adhering to essentially the same axioms available for alveolar-like cystogenesis. In silico cell proliferation was not needed. The analogue recovered within a few simulation cycles but required a longer recovery time for larger or multiple wounds. In simulated monolayer wound repair, diffusive factor-mediated ‘cell’ migration led to repair patterns comparable to those of in vitro cultures exposed to different growth factors. Simulations predicted directional cell locomotion to be critical for successful in vitro wound repair. We anticipate that with further use and refinement, the methods used will develop as a rigorous, extensible means of unravelling mechanisms of lung alveolar repair and regeneration.     

Effect of calcium phosphate glass on bone formation in calvarial defects of Sprague-Dawley rats

The purpose of this study was to investigate the bone regenerative effect of calcium phosphate glass in vivo. We prepared two different sizes of calcium phosphate glass powder using the system CaO-CaF₂-P₂O₅-MgO-ZnO; the particle size of the powders were 400 μm and 40 μm. 8 mm calvarial critical-sized defects were created in 60 male Sprague-Dawley rats. The animals were divided into 3 groups of 20 animals each. Each defect was filled with a constant weight of 0.5 g calcium phosphate glass powder mixed with saline. As controls, the defect was left empty. The rats were sacrificed 2 or 8 weeks after postsurgery, and the results were evaluated using radiodensitometric and histological studies; they were also examined histomorphometrically. When the bigger powders with 400 μm particle were grafted, the defects were nearly completely filled with new-formed bone in a clean healing condition after 8 week. When smaller powders with 40 μm particle were transplanted, new bone formation was even lower than the control group due to a lot of inflammatory cell infiltration. It was concluded that the prepared calcium phosphate glass enhanced the new bone formation in the calvarial defect of Sprague-Dawley rats and it is expected to be a good potential materials for hard tissue regeneration. The particle size of the calcium phosphate was crucial; 400 μm particles promoted new bone formation, while 40 μm particles inhibited it because of severe inflammation.     

In vitro investigations of a novel wound dressing concept based on biodegradable polyurethane

Abstract

Non-healing and partially healing wounds are an important problem not only for the patient but also for the public health care system. Current treatment solutions are far from optimal regarding the chosen material properties as well as price and source. Biodegradable polyurethane (PUR) scaffolds have shown great promise for in vivo tissue engineering approaches, but accomplishment of the goal of scaffold degradation and new tissue formation developing in parallel has not been observed so far in skin wound repair. In this study, the mechanical properties and degradation behavior as well as the biocompatibility of a low-cost synthetic, pathogen-free, biocompatible and biodegradable extracellular matrix mimicking a PUR scaffold was evaluated in vitro. The novel PUR scaffolds were found to meet all the requirements for optimal scaffolds and wound dressings. These three-dimensional scaffolds are soft, highly porous, and form-stable and can be easily cut into any shape desired. All the material formulations investigated were found to be nontoxic. One formulation was able to be defined that supported both good fibroblast cell attachment and cell proliferation to colonize the scaffold. Tunable biodegradation velocity of the materials could be observed, and the results additionally indicated that calcium plays a crucial role in PUR degradation. Our results suggest that the PUR materials evaluated in this study are promising candidates for next-generation wound treatment systems and support the concept of using foam scaffolds for improved in vivo tissue engineering and regeneration.     

Large-Scale Fabrication of Robust Artificial Skins from a Biodegradable Sealant-Loaded Nanofiber Scaffold to Skin Tissue via Microfluidic Blow-Spinning

Given that many people suffer from large-area skin damage, skin regeneration is a matter of high concern. Here, an available method is developed for the formation of large-area robust skins through three stages: fabrication of a biodegradable sealant-loaded nanofiber scaffold (SNS), skin tissue reconstruction, and skin regeneration. First, a microfluidic blow-spinning strategy is proposed to fabricate a large-scale nanofiber scaffold with an area of 140 cm × 40 cm, composed of fibrinogen-loaded polycaprolactone/silk fibroin (PCL/SF) ultrafine core–shell nanofibers with mean diameter of 65 nm. Then, the SNS forms, where the gelling reaction of fibrin sealant occurs in situ between thrombin and fibrinogen on PCL/SF nanofiber surface, to promote the migration and proliferation of fibroblasts, accelerating skin regeneration. Through an in vivo study, it is shown that the SNS can rapidly repair acute tissue damage such as vascular bleeding and hepatic hemorrhage, and also promote angiogenesis, large-area abdominal wall defect repair, and wound tissue regeneration for medical problems in the world. Besides, it avoids the risk of immune rejection and secondary surgery in clinical applications. This strategy offers a facile route to regenerate large-scale robust skin, which shows great potential in abdominal wall defect repair.     

In vitro investigations of a novel wound dressing concept based on biodegradable polyurethane

Non-healing and partially healing wounds are an important problem not only for the patient but also for the public health care system. Current treatment solutions are far from optimal regarding the chosen material properties as well as price and source. Biodegradable polyurethane (PUR) scaffolds have shown great promise for in vivo tissue engineering approaches, but accomplishment of the goal of scaffold degradation and new tissue formation developing in parallel has not been observed so far in skin wound repair. In this study, the mechanical properties and degradation behavior as well as the biocompatibility of a low-cost synthetic, pathogen-free, biocompatible and biodegradable extracellular matrix mimicking a PUR scaffold was evaluated in vitro. The novel PUR scaffolds were found to meet all the requirements for optimal scaffolds and wound dressings. These three-dimensional scaffolds are soft, highly porous, and form-stable and can be easily cut into any shape desired. All the material formulations investigated were found to be nontoxic. One formulation was able to be defined that supported both good fibroblast cell attachment and cell proliferation to colonize the scaffold. Tunable biodegradation velocity of the materials could be observed, and the results additionally indicated that calcium plays a crucial role in PUR degradation. Our results suggest that the PUR materials evaluated in this study are promising candidates for next-generation wound treatment systems and support the concept of using foam scaffolds for improved in vivo tissue engineering and regeneration.     

Hyaluronic acid (HA)-based hydrogels for full-thickness wound repairing and skin regeneration

In this work, two kinds of hyaluronic acid (HA)-based hydrogels were fabricated: one is made from physical freezing-thawing of HA solution (HA1), and the other is from chemical cross-linking of HA and polysaccharide (HA2). They were applied to repair full-thickness skin defects with New Zealand rabbits as the test animals, using powder HA and cotton dress as the references. The wound starts to heal after wounds were disinfected with iodine followed by coating with HA2, HA1, HA and cotton dress (the control), respectively. They were recorded as 4 treatments (groups), HA2, HA1, HA and the control. The healing progress was followed and tested in the duration of 56 days, and the biological repairing mechanism was explored. From the wound area alteration, white blood cell (WBC) measurements and H&E staining, HA2 was the most promising treatment in promoting the wound healing with least serious scar formation. Immunochemistry analyses and real-time PCR tests of the bio-factors involved in the wound healing, vascular endothelial growth factor (VEGF), alpha-smooth muscle actin (α-SMA) and transforming growth factor beta-1 (TGF-β1), exhibited that HA2 enhanced VEGF and α-SMA secretion but reduced TGF-β1 expression at early stage, which alleviated the wound inflammation, improved the skin regeneration and relieved the scar formation.     

In vitro evaluation of biodegradable nHAP‐Chitosan‐Gelatin‐based scaffold for tissue engineering application

The present study focuses on fabrication and characterisation of porous composite scaffold containing hydroxyapatite (HAP), chitosan, and gelatin with an average pore size of 250–1010 nm for improving wound repair and regeneration by Electrospinning method. From the results of X ‐Ray Diffraction (XRD) study, the peaks correspond to crystallographic structure of HAP powder. The presence of functional group bonds of HAP powder, Chitosan and scaffold was studied using Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology of the scaffold was observed using Scanning Electron Microscope (SEM). The Bioactivity of the Nano composite scaffolds was studied using simulated body fluid solution at 37 ± 1°C. The biodegradability test was studied using Tris‐Buffer solution for the prepared nanocomposites [nano Chitosan, nano Chitosan gelatin, Nano based Hydroxyapatite Chitosan gelatin]. The cell migration and potential biocompatibility of nHAP‐chitosan‐gelatin scaffold was assessed via wound scratch assay and were compared to povedeen as control. Cytocompatibility evaluation for Vero Cells using wound scratch assay showed that the fabricated porous nanocomposite scaffold possess higher cell proliferation and growth than that of povedeen. Thus, the study showed that the developed nanocomposite scaffolds are potential candidates for regenerating damaged cell tissue in wound healing process.Inspec keywords: nanofabrication, tissue engineering, electrospinning, wounds, cellular biophysics, scanning electron microscopy, surface morphology, X‐ray diffraction, biomedical materials, nanomedicine, porosity, biodegradable materials, nanoporous materials, calcium compounds, gelatin, nanocomposites, Fourier transform infrared spectra, nanoparticles, precipitation (physical chemistry)Other keywords: average pore size, wound repair, crystallographic structure, HAP powder, functional group bonds, simulated body fluid solution, biodegradability test, Tris‐Buffer solution, cell migration, wound scratch assay, tissue engineering, electrospinning method, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, biocompatibility, cytocompatibility, porous nanocomposite scaffold, cell tissue, nHAP‐chitosan‐gelatin scaffold composites, wet chemical precipitation method, surface morphology, nanohydroxyapatite‐nanochitosan‐gelatin scaffold composites, cell proliferation, wound healing, (Ca₁₀ (PO₄)₆ (OH)₂)     

Nanofibers prepared by needleless electrospinning technology as scaffolds for wound healing

Electrospun gelatin and poly-ε-caprolactone (PCL) nanofibers were prepared using needleless technology and their biocompatibility and therapeutic efficacy have been characterized in vitro in cell cultures and in an experimental model of a skin wound. Human dermal fibroblasts, keratinocytes and mesenchymal stem cells seeded on the nanofibers revealed that both nanofibers promoted cell adhesion and proliferation. The effect of nanofibers on wound healing was examined using a full thickness wound model in rats and compared with a standard control treatment with gauze. Significantly faster wound closure was found with gelatin after 5 and 10 days of treatment, but no enhancement with PCL nanofibers was observed. Histological analysis revealed enhanced epithelialisation, increased depth of granulation tissue and increased density of myofibroblasts in the wound area with gelatin nanofibers. The results show that gelatin nanofibers produced by needleless technology accelerate wound healing and may be suitable as a scaffold for cell transfer and skin regeneration.     

Hierarchically multifunctional bioactive nanoglass for integrated tumor/infection therapy and impaired wound repair

The complex wound repair induced by tumor surgery and infection is still the clinical challenge due to the subsequent tumor recurrence and serious inflammation. Herein, we develop a bioactive Si-Ca-Sr glass-based therapy-regeneration-enabled nanohybrids (BSr@PPE) with hierarchical versatility for overcoming the challenges of tumor and infection-impaired wound repair. BSr@PPE showed a representative concentration-dependent photothermal effect, strong free radical scavenging and antibacterial ability, as well as good UV-shielding properties and high biocompatibility. BSr@PPE could efficiently kill tumor cells through the photothermal effect, show the robust antibacterial activity against normal and multi-drug resistant bacteria and enhance the fibroblasts migration in vitro. In vivo animal experiments suggested that BSr@PPE could effectively promote epithelial reconstruction, collagen deposition and angiogenesis in normal wounds, reduce inflammation and enhance repair in multi-drug bacterial infected wounds, accelerate the tumor-impaired wound through inhibit the tumor cells. This work may provide a new strategy and multifunctional bioactive material for treating the tissue repair and regeneration under the multi-pathological environments.     

Experimental wound dressings of degradable PHA for skin defect repair

The present study reports construction of wound dressing materials from degradable natural polymers such as hydroxy derivatives of carboxylic acids (PHAs) and 3-hydroxybutyrate/4-hydroxybutyrate [P(3HB/4HB)] as copolymer. The developed polymer films and electrospun membranes were evaluated for its wound healing properties with Grafts—elastic nonwoven membranes carrying fibroblast cells derived from adipose tissue multipotent mesenchymal stem cells. The efficacy of nonwoven membranes of P(3HB/4HB) carrying the culture of allogenic fibroblasts was assessed against model skin defects in Wistar rats. The morphological, histological and molecular studies revealed the presence of fibroblasts on dressing materials which facilitated wound healing, vascularization and regeneration. Further it was also observed that cells secreted extracellular matrix proteins which formed a layer on the surface of membranes and promoted the migration of epidermal cells from the neighboring tissues surrounding the wound. The wounds under the P(3HB/4HB) membrane carrying cells healed 1.4 times faster than the wounds under the cell-free membrane and 3.5 times faster than the wounds healing under the eschar (control).The complete wound healing process was achieved at Day 14. Thus the study highlights the importance of nonwoven membranes developed from degradable P(3HB/4HB) polymers in reducing inflammation, enhancing angiogenic properties of skin and facilitating better wound healing process.     

Assessment of reinforced poly(ethylene glycol) chitosan hydrogels as dressings in a mouse skin wound defect model

Wound dressings of chitosan are biocompatible, biodegradable, antibacterial and hemostatic biomaterials. However, applications for chitosan are limited due to its poor mechanical properties. Here, we conducted an in vivo mouse angiogenesis study on reinforced poly(ethylene glycol) (PEG)-chitosan (RPC) hydrogels. RPC hydrogels were formed by cross-linking chitosan with PEGs of different molecular weights at various PEG to chitosan ratios in our previous paper. These dressings can keep the wound moist, had good gas exchange capacity, and was capable of absorbing or removing the wound exudate. We examined the ability of these RPC hydrogels and neat chitosan to heal small cuts and full-thickness skin defects on the backs of male Balb/c mice. Histological examination revealed that chitosan suppressed the infiltration of inflammatory cells and accelerated fibroblast proliferation, while PEG enhanced epithelial migration. The RPC hydrogels promoted wound healing in the small cuts and full layer wounds. The optimal RPC hydrogel had a swelling ratio of 100% and a water vapor transmission rate (WVTR) of about 2000 g/m²/day. In addition, they possess good mechanical property and appropriate degradation rates. Thus, the optimal RPC hydrogel formulation functioned effectively as a wound dressing and promoted wound healing.     

PLLA–collagen and PLLA–gelatin hybrid scaffolds with funnel-like porous structure for skin tissue engineering

In skin tissue engineering, a three-dimensional porous scaffold is necessary to support cell adhesion and proliferation and to guide cells moving into the repair area in the wound healing process. Structurally, the porous scaffold should have an open and interconnected porous architecture to facilitate homogenous cell distribution. Moreover, the scaffolds should be mechanically strong to protect deformation during the formation of new skin. In this study, the hybrid scaffolds were prepared by forming funnel-like collagen or gelatin sponge on a woven poly(l-lactic acid) (PLLA) mesh. The hybrid scaffolds combined the advantages of both collagen or gelatin (good cell-interactions) and PLLA mesh (high mechanical strength). The hybrid scaffolds were used to culture dermal fibroblasts for dermal tissue engineering. The funnel-like porous structure promoted homogeneous cell distribution and extracellular matrix production. The PLLA mesh reinforced the scaffold to avoid deformation. Subcutaneous implantation showed that the PLLA–collagen and PLLA–gelatin scaffolds promoted the regeneration of dermal tissue and epidermis and reduced contraction during the formation of new tissue. These results indicate that funnel-like hybrid scaffolds can be used for skin tissue regeneration.     

Hydrogels containing rutin intended for cutaneous administration: efficacy in wound healing in rats

Objective: Development of a hydrogel containing rutin at 0.025% (w/w) and evaluation of its in vivo efficacy in cutaneous wound healing in rats.

Methods: Hydrogels were prepared using Carbopol Ultrez^® 10 NF and an aqueous dispersion of rutin in polysorbate 80. Hydrogels were characterized by means of pH measurement, rheological and spreadability analysis and rutin content determination by liquid chromatography. The in vivo healing effect was evaluated through the regression of skin lesions in rats and by analysis of oxidative stress.

Results and discussion: Hydrogels showed adequate pH values (5.50–6.50) and pseudoplastic non-Newtonian behavior. After 5 days of treatment of wounds, hydrogels containing rutin presented a higher decrease in the wound area compared to the control hydrogels. Analysis of the oxidative stress showed a decrease in lipid peroxidation and protein carbonyl content as well as an increase in catalase activity after the treatment with the hydrogel containing rutin. Furthermore, this treatment increased total protein levels.

Conclusion: This study shows for the first time the feasibility of using dermatological formulations containing rutin to improve skin wound healing.     

Injectable melatonin-loaded carboxymethyl chitosan (CMCS)-based hydrogel accelerates wound healing by reducing inflammation and promoting angiogenesis and collagen deposition

Carboxymethyl chitosan(CMCS)-based hydrogels have antibacterial activity,and have shown the abilities of preventing wound infection,promoting cell proliferation,accelerating collagen deposition,and stimulating hyaluronic acid formation during wound healing.As a hormone produced by the pineal gland in humans and animals,melatonin promotes skin wound healing by regulating the release of inflammatory mediators and accelerating the proliferation and migration of cells,angiogenesis,and collagen deposition.However,the combined effects of CMCS and melatonin on wound healing remain unclear.Injectable CMCS-based hydrogels containing melatonin were prepared,and their healing effects were evaluated using a full-thickness cutaneous wound model in rats.Compared with the control and the hydrogel with no melatonin groups,the melatonin-loaded hydrogel significantly increased the percentage of wound closure,promoted the proliferation of granulation tissue and re-epithelialization,and accelerated collagen deposition.Additionally,the melatonin-loaded hydrogel promoted angiogenesis and vascular endothelial growth factor receptor protein expression and increased the expression of cyclooxygenase-2 and inducible nitric oxide synthase.The melatonin-loaded hydrogel also markedly increased the expression of collagen III,α-smooth muscle actin,and transforming growth factor-β1 proteins and reduced collagen I expression.These results suggest that the melatonin-loaded hydrogel promoted granulation tissue formation and accelerated wound healing by reducing inflammation and promoting angiogenesis and collagen deposition.     

An in Vitro Study on Tissue Repair: Impact of Unloading on Cells Involved in the Remodelling Phase

The number of astronauts involved in long-lasting missions and extra-vehicular activities is going to increase in the future. Consequently, the chance of injury due to traumatic events or unexpected emergency surgery will also increase and medical evacuation times to earth will be prolonged. Hence, the need to address requirements for surgery and trauma care in non terrestrial environments will be a priority. Tissue repair in weightlessness should therefore be regarded as a major issue not enough studied to date. Wound healing is a complex multi-step process, crucial to the survival of the organism. It starts with an inflammatory phase followed by a remodelling phase. During repair, the extracellular matrix (ECM) is sequentially remodelled by the concerted action of different cell types, in order to rebuild a functional tissue. The available literature concerning wound healing with mechanical unloading presents controversial results. However, many studies indicate impairment of the healing processes. Here we present a study on the behaviour of cells involved in the remodelling phase of repair, e.g. fibroblasts and endothelial cells, in response to microgravity (μg). In particular, their adhesion/migration, cytoskeleton organization, production of ECM molecules and receptors have been investigated. Cell response to pulsed Nd:YAG laser irradiation has also been investigated in order to evaluate the possibility to use laser irradiation for counteracting the effect of μg on wound healing. In μg, we observed alterations in production/assembling of ECM molecules. Increased fibronectin (FN) and laminin (LM) could be the cause for impaired ECM rebuilding and altered cell adhesion/migration. Treatment with Nd:YAG laser pulses induced organized fibrillogenesis and favoured endothelial cell spreading and monolayer formation. These findings open the way for a better understanding of tissue repair mechanisms in space and future clinical applications on earth.     

PLLA–collagen and PLLA–gelatin hybrid scaffolds with funnel-like porous structure for skin tissue engineering

Abstract

In skin tissue engineering, a three-dimensional porous scaffold is necessary to support cell adhesion and proliferation and to guide cells moving into the repair area in the wound healing process. Structurally, the porous scaffold should have an open and interconnected porous architecture to facilitate homogenous cell distribution. Moreover, the scaffolds should be mechanically strong to protect deformation during the formation of new skin. In this study, the hybrid scaffolds were prepared by forming funnel-like collagen or gelatin sponge on a woven poly(l-lactic acid) (PLLA) mesh. The hybrid scaffolds combined the advantages of both collagen or gelatin (good cell-interactions) and PLLA mesh (high mechanical strength). The hybrid scaffolds were used to culture dermal fibroblasts for dermal tissue engineering. The funnel-like porous structure promoted homogeneous cell distribution and extracellular matrix production. The PLLA mesh reinforced the scaffold to avoid deformation. Subcutaneous implantation showed that the PLLA–collagen and PLLA–gelatin scaffolds promoted the regeneration of dermal tissue and epidermis and reduced contraction during the formation of new tissue. These results indicate that funnel-like hybrid scaffolds can be used for skin tissue regeneration.     

Comparison of periodontal ligament cells responses to dense and nanophase hydroxyapatite

Hydroxyapatite, a synthetic calcium phosphate ceramic, is used as a biomaterial for the restoration of human hard tissue as well as in techniques which aim to regenerate periodontal tissues. Generally, hydroxyapatite is believed to have osteoconductive effects and to be non-bioresorbable but not to induce to periodontal tissue regeneration. No report has been found on responses of periodontal ligament cells (PDLC), the main contributor to periodontal tissue regeneration, to nanoparticles of hydroxyapatite. The objective of this study was to investigate the possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Using a sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved to comprise nanoparticles by transmission electron microscope examination. The primary periodontal ligament cells were cultured on dense particle hydroxyapatite and nanometer particle hydroxyapatite. The effects on proliferation of periodontal ligament cells on dense and nanoparticle hydroxyapatite were examined in vitro using a methyl thiazolil tetracolium (MTT) test. The intercellular effects were studied with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). In addition, the influence of the two materials on osteogenic differentiation was determined through measurement of alkaline phosphatase activity and flow cytometry. About 2, 3, and 4 days after treatment with nanoparticles of hydroxyapatite, the proliferation activity of the PDLC increased significantly compared with those proliferating on dense hydroxyapatite and of control PDLC, but no significant difference was found between the PDLC proliferation on dense hydroxyapatite and the control PDLCs. After 3 and 5 days’ incubation with nanoparticles of hydroxyapatite, alkaline phosphatase activity was significantly increased as compared to PDLCs incubated with dense hydroxyapatite and control PDLCs. Intracellular engulfment was found in the cultured cells with nanophase hydroxyapatite under electron microscopy. The results suggest that nanophase hydroxyapatite can promote proliferation and osteogenic differentiation of periodontal ligament cells and further that it may be used as a bioresorbable agent in osseous restoration.     

生物玻璃在组织修复中的研究进展

生物玻璃最早被应用于硬骨组织修复,近些年越来越多的研究证明其还可用于修复软骨和软组织,如皮肤、角膜、肺、神经组织等。具有代表性的生物玻璃包括硅酸盐生物玻璃和硼酸盐生物玻璃,这类生物玻璃在体内环境中能够快速释放大量的离子,发挥特殊的生物学效应,如抑菌活性,细胞附着、繁殖和迁移、血管生成等。掺杂元素对生物玻璃的性能起到重要的作用,进而调控组织修复中的不同效果。并且,生物玻璃的结构也对细胞的生长及组织修复有着重要的作用。由于生物玻璃韧性低、脆性高,常与金属、多聚物等制备成复合材料应用于组织修复。综述了生物玻璃物理化学性质与生物学活性的关系,同时介绍和探讨了基于生物玻璃衍生出来的复合材料及其应用,为开发新型的组织修复材料提供参考。     

Orientational Coupling Locally Orchestrates a Cell Migration Pattern for Re‐Epithelialization

Re‐epithelialization by collective migration of epithelial cells over a heterogeneous environment to restore tissue integrity and functions is critical for development and regeneration. Here, it is reported that the spatial organization of adjacent adherent paths within sparsely distributed extracellular matrix (ECM) has a significant impact on the orientational coupling between cell polarization and collective cell migration. This coupling effect determines the migration pattern for human keratinocytes to regain their cohesion, which impacts the occupancy of epithelial bridge and the migration velocity in wound repair. Statistical studies suggest the converging organization of ECM, in which adjacent paths become closer to each other and finally converge to a junctional point, facilitating collective cell migration mostly within variable ECM organization, as the polarization of the advancing cell sheet is remodeled to align along the direction of cell migration. The findings may help to design implantable ECM to optimize efficient skin regeneration.