Combined gene and stem cell therapy for cutaneous wound healing

In current medical practice, wound therapy remains a clinical challenge and much effort has been focused on the development of novel therapeutic approaches for wound treatment. Gene therapy, initially developed for treatment of congenital defects, represents a promising option for enhancing wound repair. In order to accelerate wound closure, genes encoding for growth factors or cytokines have shown the most potential. The majority of gene delivery systems are based on viral transfection, naked DNA application, high pressure injection, and liposomal vectors. Besides advances stemming from breakthroughs in recombinant growth factors and bioengineered skin, there has been a significant increase in the understanding of stem cell biology in the field of cutaneous wound healing. A variety of sources, such as bone marrow, umbilical cord blood, adipose tissue and skin/hair follicles, have been utilized to isolate stem cells and to modulate the healing response of acute and chronic wounds. Recent data have demonstrated the feasibility of autologous adult stem cell therapy in cutaneous repair and regeneration. Very recently, stem cell based skin engineering in conjunction with gene recombination, in which the stem cells act as both the seed cells and the vehicle for gene delivery to the wound site, represents the most attractive field for generating a regenerative strategy for wound therapy. The aim of this article is to discuss the use and the potential of these novel technologies in order to improve wound healing capacities.     

Strategies for controlled delivery of growth factors and cells for bone regeneration

The controlled delivery of growth factors and cells within biomaterial carriers can enhance and accelerate functional bone formation. The carrier system can be designed with pre-programmed release kinetics to deliver bioactive molecules in a localized, spatiotemporal manner most similar to the natural wound healing process. The carrier can also act as an extracellular matrix-mimicking substrate for promoting osteoprogenitor cellular infiltration and proliferation for integrative tissue repair. This review discusses the role of various regenerative factors involved in bone healing and their appropriate combinations with different delivery systems for augmenting bone regeneration. The general requirements of protein, cell and gene therapy are described, with elaboration on how the selection of materials, configurations and processing affects growth factor and cell delivery and regenerative efficacy in both in vitro and in vivo applications for bone tissue engineering.     

Exosome loaded genipin crosslinked hydrogel facilitates full thickness cutaneous wound healing in rat animal model

Full thickness cutaneous wound therapy and regeneration remains a critical challenge in clinical therapeutics. Recent reports have suggested that mesenchymal stem cells exosomes therapy is a promising technology with great potential to efficiently promote tissue regeneration. Multifunctional hydrogel composed of both synthetic materials and natural materials is an effective carrier for exosomes loading. Herein, we constructed a biodegradable, dual-sensitive hydrogel encapsulated human umbilical cord-mesenchymal stem cells (hUCMSCs) derived exosomes to facilitate wound healing and skin regeneration process. The materials characterization, exosomes identification, and in vivo full-thickness cutaneous wound healing effect of the hydrogels were performed and evaluated. The in vivo results demonstrated the exosomes loaded hydrogel had significantly improved wound closure, re-epithelialization rates, collagen deposition in the wound sites. More skin appendages were observed in exosomes loaded hydrogel treated wound, indicating the potential to achieve complete skin regeneration. This study provides a new access for complete cutaneous wound regeneration via a genipin crosslinked dual-sensitive hydrogel loading hUCMSCs derived exosomes.     

Bilayer hydrogel dressing with lysozyme-enhanced photothermal therapy for biofilm eradication and accelerated chronic wound repair

Biofilms are closely associated with the tough healing and dysfunctional inflammation of chronic wounds. Photothermal therapy (PTT) emerged as a suitable alternative which could destroy the structure of biofilms with local physical heat. However, the efficacy of PTT is limited because the excessive hyperthermia could damage surrounding tissues. Besides, the difficult reserve and delivery of photothermal agents makes PTT hard to eradicate biofilms as expectation. Herein, we present a GelMA-EGF/Gelatin-MPDA-LZM bilayer hydrogel dressing to perform lysozyme-enhanced PTT for biofilms eradication and a further acceleration to the repair of chronic wounds. Gelatin was used as inner layer hydrogel to reserve lysozyme (LZM) loaded mesoporous polydopamine (MPDA) (MPDA-LZM) nanoparticles, which could rapidly liquefy while temperature rising so as to achieve a bulk release of nanoparticles. MPDA-LZM nanoparticles serve as photothermal agents with antibacterial capability, could deeply penetrate and destroy biofilms. In addition, the outer layer hydrogel consisted of gelatin methacryloyl (GelMA) and epidermal growth factor (EGF) promoted wound healing and tissue regeneration. It displayed remarkable efficacy on alleviating infection and accelerating wound healing in vivo. Overall, the innovative therapeutic strategy we came up with has significant effect on biofilms eradication and shows promising application in promoting the repair of clinical chronic wounds.     

Growth factor delivery for bone tissue engineering

Bone is a dynamic tissue that undergoes significant turnover during the life cycle of an individual. Despite having a significant regenerative capability, trauma and other pathological scenarios commonly require therapeutic intervention to facilitate the healing process. Bone tissue engineering, where cellular and biological processes at a site are deliberately manipulated for a therapeutic outcome, offers a viable option for the treatment of skeletal diseases. In this review paper, we aim to provide a brief synopsis of cellular and molecular basis of bone formation that are pertinent to current efforts of bone healing. Different approaches for engineering bone tissue were presented with special emphasis on the use of soluble (diffusible) therapeutic agents to accelerate bone healing. The latter agents have been used for both local bone repair (i.e. introduction of agents directly to a site of repair) as well as systemic bone regeneration (i.e. delivery for regeneration throughout the skeletal system). Critical drug delivery and targeting issues pertinent for each mode of bone regeneration are provided. In addition, future challenges and opportunities in bone tissue engineering are proposed from the authors' perspective.     

In situ injectable nano-composite hydrogel composed of curcumin, N,O-carboxymethyl chitosan and oxidized alginate for wound healing application

In this paper, an in situ injectable nano-composite hydrogel composed of curcumin, N,O-carboxymethyl chitosan and oxidized alginate as a novel wound dressing was successfully developed for the dermal wound repair application. Nano-curcumin with improved stability and similar antioxidant efficiency compared with that of unmodified curcumin was developed by using methoxy poly(ethylene glycol)-b-poly(?-caprolactone) copolymer (MPEG-PCL) as carrier followed by incorporating into the N,O-carboxymethyl chitosan/oxidized alginate hydrogel (CCS-OA hydrogel). In vitro release study revealed that the encapsulated nano-curcumin was slowly released from CCS-OA hydrogel with the diffusion-controllable manner at initial phase followed by the corrosion manner of hydrogel at terminal phase. In vivo wound healing study was performed by injecting hydrogels on rat dorsal wounds. Histological study revealed that application of nano-curcumin/CCS-OA hydrogel could significantly enhance the re-epithelialization of epidermis and collagen deposition in the wound tissue. DNA, protein and hydroxyproline content in wound tissue from each group were measured on 7th day of post wounding and the results also indicated that combined using nano-curcumin and CCS-OA hydrogel could significantly accelerate the process of wound healing. Therefore, all these results suggested that the developed nano-curcumin/CCS-OA hydrogel as a promising wound dressing might have potential application in the wound healing.     

Topical disposition of two strengths of a 125I-rhEGF jelly in rat skin wounds

Growth factors have proved to be an effective therapeutic strategy. However, some controversies have arisen concerning their efficacy in topical wound treatments. Stabilization of epidermal growth factors at the wound site and long-lasting receptor occupancy are important factors for wound repair. This study evaluated the cumulative profiles of two jellies containing 10 or 20 microg of 125I-rhEGF per gram of jelly, in a rat full-thickness skin lesion model. The prolonged time-courses at the wound sites for both strengths compared with saline solutions previously evaluated using a similar skin lesion model are reported. It seems that these two topical formulations that provide more sustained amounts of 125I-rhEGF over the period of sampling, would probably achieve the required wound healing response in terms of cell proliferation, collagen deposition and protein synthesis. Further studies need to be developed in order to elucidate whether such an in vivo disposition pattern is consistent with an earlier and stronger promotion of wound healing events.     

Biomimetic materials for tissue engineering

Tissue engineering and regenerative medicine is an exciting research area that aims at regenerative alternatives to harvested tissues for transplantation. Biomaterials play a pivotal role as scaffolds to provide three-dimensional templates and synthetic extracellular matrix environments for tissue regeneration. It is often beneficial for the scaffolds to mimic certain advantageous characteristics of the natural extracellular matrix, or developmental or wound healing programs. This article reviews current biomimetic materials approaches in tissue engineering. These include synthesis to achieve certain compositions or properties similar to those of the extracellular matrix, novel processing technologies to achieve structural features mimicking the extracellular matrix on various levels, approaches to emulate cell-extracellular matrix interactions, and biologic delivery strategies to recapitulate a signaling cascade or developmental/wound healing program. The article also provides examples of enhanced cellular/tissue functions and regenerative outcomes, demonstrating the excitement and significance of the biomimetic materials for tissue engineering and regeneration.     

Neem (Azadirachta Indica) and silk fibroin associated hydrogel: Boon for wound healing treatment regimen

Background & ObjectivesWound healing is the complex physiological process of replacing damaged cells or tissue layers. The neem (Azadirachta Indica) has a variety of biological activities, which may hasten the rate at which the wound healing mechanism occurs. Silk fibroin is a biomaterial that is reported for its tissue regeneration activity. So, the present study was designed to assess the effectiveness of a hydrogel comprising neem and silk fibroin biomaterials for the treatment of wounds.MethodsTopical neem hydrogels (N-HG) with and without silk fibroin (N-SFB-HG) were prepared using neem extract, silk fibroin, and guar gum, which act by entrapping the components by forming a gel. Evaluation tests such as Fourier transform infrared spectroscopy (FT-IR), visual emergence, pH, rheological behavior, spreading capacity, drug content, skin irritation, anti-microbial action, in vivo wound healing activity, and stability were carried out.ResultsThe FT-IR results showed no chemical interaction between the constituents. The formed hydrogels had pH values of 5.87 ± 0.3 for N-HG and 5.76 ± 0.2 for N-SFB-HG. The preferred topical gel viscosity was observed in the N-HG (54.2 ± 3.2cPs) and N-SFB-HG (59.9 ± 4.8cPs) formulations. The formulated hydrogels were sterile and did not irritate the skin. The in vivo wound healing investigation results reveal that the N-SF-HG treatment speeds up the regeneration of the injured area faster when compared to control and N-HG treated groups.Interpretation & ConclusionThese results support the efficacy of the topical hydrogel formulation, including neem and silk fibroin. Therefore, the neem-silk fibroin hydrogel formulation is a therapeutically viable choice that, following necessary clinical research, might be utilized in novel formulations for managing chronic wounds.     

Therapeutic effects of nanogel containing triterpenoids isolated from Ganoderma lucidum (GLT) using therapeutic ultrasound (TUS) for frostbite in rats

Objective: The aim of this study was to evaluate the effect of therapeutic ultrasound (TUS) on dermal delivery and therapeutic effect for frostbite of nanogel containing triterpenoids isolated from Ganoderma lucidum (GLT).

Methods: GLT nanosuspension (GLT-NS) was prepared by high pressure homogenization and then suitably gelled to obtain GLT nanogel. The effects of TUS on GLT releasing from GLT nanogel and GLT permeation through the excised rat abdominal skin were evaluated. Moreover, a comparative study was also undertaken between different treatments of frostbite in rats: topical application of GLT nanogel (alone), TUS (alone) and GLT nanogel?+?TUS (plus).

Results: In the in vitro release study, TUS has no influence on drug release from the nanogel. Results of the in vitro transdermal study indicated that TUS significantly increased the cumulative amount of GLT permeating across and into the skin and reduced the lag time in comparison with passive diffusion (without TUS). As evidenced by the significant increase of wound healing area and the improvement in frostbite, TUS applied with simultaneous treatment method could improve the therapeutic effect of the GLT nanogel for frostbite.

Conclusion: The present study revealed that the TUS can be effectively used to actively enhance topical delivery of GLT from nanogel and improve the therapeutic effect for frostbite in rats.     

新型局部给药系统促进创伤愈合的研究进展

目的 皮肤组织的创伤修复是临床常见的问题,对于创伤的治疗手段多种多样。方法 对近几年的相关创伤愈合文献进行整理、分析和归纳。结果 阐述了皮肤组织愈合的机制及用于创伤治疗的新型局部给药系统。结论 新型的局部给药系统具有能够增加局部药物浓度、减少不良反应、促进伤口愈合、使用方便、提高患者依从性等特点,新型的给药系统用于治疗局部创伤具有巨大的市场潜力。     

Thermosensitive Hydrogel as a Tgf-β1 Gene Delivery Vehicle Enhances Diabetic Wound Healing

PURPOSE: To accelerate diabetic wound healing with TGF-beta1 gene delivery system using a thermosensitive hydrogel made of a triblock copolymer, PEG-PLGA-PEG. METHODS: Two 7 x 7 mm full thickness excisional wounds were created in parallel at the back of each genetically diabetic mouse. The hydrogel containing plasmid TGF-beta1 was administered to the wound and formed an adhesive film in situ. Controls were either untreated or treated with the hydrogel without DNA. We used a commercial wound dressing, Humatrix, either with or without DNA, to compare the therapeutic effect with the thermosensitive hydrogel. RESULTS: We found that thermosensitive hydrogel alone is slightly beneficial for reepithealization at early stage of healing (day 1-5), but significantly accelerated repithelializaion, increased cell proliferation, and organized collagen were observed in the wound bed treated with thermosensitive hydrogel containing plasmid TGF-beta1. The accelerated reepithelialization was accompanied with enhanced collagen synthesis and more organized extracellular matrix deposition. Humatrix alone or with plasmid TGF-beta1, had little effect. CONCLUSIONS: Thermosensitive hydrogel made of PEG-PLGA-PEG triblock copolymer provides excellent wound dressing activity and delivers plasmid TGF-beta1 to promote wound healing in a diabetic mouse model.     

鱼皮胶原蛋白-壳聚糖复合海藻酸盐水凝胶敷料对烧烫伤创面的促愈合作用

本文以海藻酸钠为原料,复配壳聚糖、鱼皮胶原蛋白,通过Ca2+离子交联制备成海藻酸盐水凝胶敷料。测试了该敷料的物理机械性能及其对大白兔浅Ⅱ度烧烫伤创面的促愈合作用。结果表明：鱼皮胶原蛋白-壳聚糖复合海藻酸盐水凝胶的含水量≥80%,具有良好的吸湿保湿和机械性能,是一种理想的伤口创面敷料;对浅Ⅱ度烧烫伤的愈合周期远远少于医用纱布、市售聚氨酯水凝胶敷料,且能消除伤口炎症,抑制瘢痕的生成,在伤口护理方面有着良好的前景和应用方向。     

Biomedical potential of clay nanotube formulations and their toxicity assessment

ABSTRACT

Introduction: Halloysite clay nanotubes (HNTs) are a naturally abundant and biocompatible aluminosilicate material with a structure able to encapsulate 10–20% of drugs. These features are attractive toward the clinical application in controlled drug delivery, tissue engineering and regenerative medicine.

Areas covered: We describe the application of HNTs as a viable method for clinical purposes, particularly developing formulations for prophylaxis, diagnosis and therapeutics, having a special attention to these nanotubes bio-safety. HNTs may be used for pharmaceuticals, biopharmaceuticals, wound healing, bone regeneration, dental repair, hair surface engineering and biomimetic applications.

Expert opinion: HNTs are a versatile, safe and biocompatible nanomaterial used for drug encapsulation for numerous clinical applications. The studies here reviewed confirm the HNTs biocompatibility, describing their low toxicity. Further developments will be made regarding the long-term efficacy of halloysite-based treatments in humans, concentrating mostly on topical applications.     

Bone mesenchymal stem cell-derived exosomes involved co-delivery and synergism effect with icariin via mussel-inspired multifunctional hydrogel for cartilage protection

Mesenchymal stem cells (MSC) are particularly effective in promoting cartilage regeneration due to their immunomodulatory, anti-inflammatory and regenerative repair functions of tissues and organs. Meanwhile, the intra-articular delivery and synergy with other therapeutic drugs have been the key issues driving their further application. We report a mussel-inspired multifunctional hydrogel system, which could achieve co-delivery and synergism effect of MSC-derived exosomes (Exos) with icariin (ICA). The ICA and Exos co-delivered articular cavity injection system are expected to retain in the joint cavity and promote cartilage regeneration, due to the thermosensitive, self-healing and adhesion properties of the mussel-inspired multifunctional hydrogel. The experimental results proved that Exos enhanced the cellular uptake of ICA by more than 2-fold evenly, and the synergism of Exos and ICA efficiently improve the cell proliferation and migration. After synergic treatment, the content of matrix metalloproteinase 13 in the supernatant and intracellular decreased by 47% and 59%, respectively. In vivo study, ICA-loaded Exos exhibited prolonged retention behavior by multifunctional hydrogel delivery, thus displayed an increased cartilage protection. In the model of osteoarthritis, co-delivery hydrogel system relieved the cartilage recession, ensuring appropriate cartilage thickness.     

Current evidence on immunological and regenerative effects of menstrual blood stem cells seeded on scaffold consisting of amniotic membrane and silk fibroin in chronic wound

Wound healing process is a complex of overlapping and coordinated events progresses beyond the inflammatory phase toward wound resolution, whereas chronic wounds fail to terminate inflammatory phase and could not develop toward regenerative state. The immunopathology of chronic wounds has been attributed to the prolonged inflammation and dysregulation of microenvironments responsible for imbalance between pro-inflammatory and anti-inflammatory states, as well as cellular and tissue senescence.We here discuss that menstrual blood-derived mesenchymal stem cells (MenSCs) with their authentic functions especially immunosuppressive, angiogenic and migratory properties in combination with a bilayer amniotic membrane/nano-fibrous fibroin scaffold could bring about effective regenerative effects in healing of chronic wound. To debate, following evidences have been cumulated : 1) Persistent pro-inflammatory state in chronic wound bed could inhibit wound resolution; 2) MenSCs exhibit noticeable regenerative, immunosuppressive effects and immunomodulatory activity, 3) The migratory characteristics of MenSCs may not be sufficient for their homing to chronic wounds site, and 4) Bilayer scaffold composed of amniotic membrane and silk fibroin induces MenSCs differentiation into keratinocyte-like cells and stimulates skin regeneration.     

Antibacterial biomaterials for skin wound dressing

Bacterial infection and the ever-increasing bacterial resistance have imposed severe threat to human health. And bacterial contamination could significantly menace the wound healing process. Considering the sophisticated wound healing process, novel strategies for skin tissue engineering are focused on the integration of bioactive ingredients,antibacterial agents included, into biomaterials with different morphologies to improve cell behaviors and promote wound healing. However, a comprehensive ...     

基于动态共价键的多糖水凝胶在药物递送及组织修复中的应用研究进展

水凝胶具有良好的生物相容性和生物降解性,广泛应用于药物递送、伤口敷料和组织工程等生物医学领域。按照材料来源可分为合成材料水凝胶和天然材料水凝胶,其中天然多糖水凝胶不仅可以作为材料应用,还具有独特的药理活性和较好的机械性能,逐渐成为首选材料。动态共价键水凝胶由于其结构灵活性、自愈合性能和环境响应性备受关注。本文对采用动态键方式的天然多糖水凝胶体系进行归类和总结,并对该类水凝胶在药物递送以及组织修复方面的研究现状进行概述,以期为新型多糖水凝胶的临床应用提供借鉴。     

Controlled local drug delivery strategies from chitosan hydrogels for wound healing

Introduction: The main target of tissue engineering is the preparation and application of adequate materials for the design and production of scaffolds, that possess properties promoting cell adhesion, proliferation and differentiation. The use of natural polysaccharides, such as chitosan, to prepare hydrogels for wound healing and controlled drug delivery is a research topic of wide and increasing interest.

Areas covered: This review presents the latest results and challenges in the preparation of chitosan and chitosan-based scaffold/hydrogel for wound healing applications. A detailed overview of their behavior in terms of controlled drug delivery, divided by drug categories, and efficacy was provided and critically discussed.

Expert opinion: The need to establish and exploit the advantages of natural biomaterials in combination with active compounds is playing a pivotal role in the regenerative medicine fields. The challenges posed by the many variables affecting tissue repair and regeneration need to be standardized and adhere to recognized guidelines to improve the quality of evidence in the wound healing process. Currently, different methodologies are followed to prepare innovative scaffold formulations and structures. Innovative technologies such as 3D printing or bio-electrospray are promising to create chitosan-based scaffolds with finely controlled structures with customizable shape porosity and thickness. Chitosan scaffolds could be designed in combination with a variety of polysaccharides or active compounds with selected and reproducible spacial distribution, providing active wound dressing with highly tunable controlled drug delivery.