Collagen/GAG scaffolds activated by RALA-siMMP-9 complexes with potential for improved diabetic foot ulcer healing

Advances in skin gene therapy: utilizing innovative dressing scaffolds for wound healing, a comprehensive review

The skin, serving as the body's outermost layer, boasts a vast area and intricate structure, functioning as the primary barrier against external threats. Disruptions in the composition and functionality of the skin can lead to a diverse array of skin conditions, such as wounds, burns, and diabetic ulcers, along with inflammatory disorders, infections, and various types of skin cancer. These disorders not only exacerbate concerns regarding skin health and beauty but also have a significant impact on mental well-being. Due to the complexity of these disorders, conventional treatments often prove insufficient, necessitating the exploration of new therapeutic approaches. Researchers develop new therapies by deciphering these intricacies and gaining a thorough understanding of the protein networks and molecular processes in skin. A new window of opportunity has opened up for improving wound healing processes because of recent advancements in skin gene therapy. To enhance skin regeneration and healing, this extensive review investigates the use of novel dressing scaffolds in conjunction with gene therapy approaches. Scaffolds that do double duty as wound protectors and vectors for therapeutic gene delivery are being developed using innovative biomaterials. To improve cellular responses and speed healing, these state-of-the-art scaffolds allow for the targeted delivery and sustained release of genetic material. The most recent developments in gene therapy techniques include RNA interference, CRISPR-based gene editing, and the utilization of viral and non-viral vectors in conjunction with scaffolds, which were reviewed here to overcome skin disorders and wound complications. In the future, there will be rare chances to develop custom methods for skin health care thanks to the combination of modern technology and collaboration among disciplines.

Small interfering RNA (siRNA) as a potential gene silencing strategy for diabetes and associated complications: challenges and future perspectives

Objective

This article critically reviews the recent search on the use of Small Interfering RNA (siRNA) in the process of gene regulation that has been harnessed to silence specific genes in various cell types, including those involved in diabetes complications.

Significance

Diabetes, a prevalent and severe condition, poses life-threatening risks due to elevated blood glucose levels. It results from inadequate insulin production by the pancreas or ineffective insulin utilization by the body. Recent research suggests siRNA could hold promise in addressing diabetes complications.

Methods

In this review, we discussed several subjects, including diabetes; its function, and common treatment options. An in-depth analysis of gene silencing method for siRNA and role of siRNA in diabetes, focusing on its impact on glucose homeostasis, diabetic retinopathy, wound healing, diabetic nephropathy and peripheral neuropathy, diabetic foot ulcers, diabetic atherosclerosis, and diabetic cardiomyopathy.

Result

siRNA-based treatment has the potential to target specific genes without disrupting several other endogenous pathways, which decreases the risk of off-target effects. In addition, siRNA has the capability to provide long-term efficacy with a single dose which will reduce treatment options and enhance patient compliance.

Conclusion

In the context of diabetic complications, siRNA has been explored as a potential therapeutic tool to modulate the expression of genes involved in various processes associated with diabetes-related issues such as Diabetic Retinopathy, Neuropathy, Nephropathy, wound healing. The use of siRNA in these contexts is still largely experimental, and challenges such as delivery to specific tissues, potential off-target effects, and long-term safety need to be addressed. Additionally, the development of siRNA-based therapies for clinical use in diabetic complications is an active area of research.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01405-7.

Nanotechnology strategies to address challenges in topical and cellular delivery of siRNAs in skin disease therapy

Gene therapy is one of the most advanced therapies in current medicine. In particular, interference RNA-based therapy by small interfering RNA (siRNA) has gained attention in recent years as it is a highly versatile, selective and specific therapy. In dermatological conditions, topical delivery of siRNA offers numerous therapeutic advantages, mainly by inhibiting the expression of target transcripts directly in the skin. However, crossing the stratum corneum and overcoming intracellular barriers is an inherent challenge. Substantial efforts by scientists have moved towards the use of multimodal and multifunctional nanoparticles to overcome these barriers and achieve greater bioavailability in their site of action, the cytoplasm. In this review the most innovative strategies based on nanoparticle and physical methods are presented, as well as the design principles and the main factors that contribute to the performance of these systems. This review also highlights the synergistic contributions of medicine, nanotechnology, and molecular biology to advancing translational research into siRNA-based therapeutics for skin diseases.

Collagen-Based Scaffolds for Chronic Skin Wound Treatment

Chronic wounds, commonly known as ulcers, represent a significant challenge to public health, impacting millions of individuals every year and imposing a significant financial burden on the global health system. Chronic wounds result from the interruption of the natural wound-healing process due to internal and/or external factors, resulting in slow or nonexistent recovery. Conventional medical approaches are often inadequate to deal with chronic wounds, necessitating the exploration of new methods to facilitate rapid and effective healing. In recent years, regenerative medicine and tissue engineering have emerged as promising avenues to encourage tissue regeneration. These approaches aim to achieve anatomical and functional restoration of the affected area through polymeric components, such as scaffolds or hydrogels. This review explores collagen-based biomaterials as potential therapeutic interventions for skin chronic wounds, specifically focusing on infective and diabetic ulcers. Hence, the different approaches described are classified on an action-mechanism basis. Understanding the issues preventing chronic wound healing and identifying effective therapeutic alternatives could indicate the best way to optimize therapeutic units and to promote more direct and efficient healing.

In situ transient transfection of 3D cell cultures and tissues, a promising tool for tissue engineering and gene therapy

Various research fields use the transfection of mammalian cells with genetic material to induce the expression of a target transgene or gene silencing. It is a tool widely used in biological research, bioproduction, and therapy. Current transfection protocols are usually performed on 2D adherent cells or suspension cultures. The important rise of new gene therapies and regenerative medicine in the last decade raises the need for new tools to empower the in situ transfection of tissues and 3D cell cultures. This review will present novel in situ transfection methods based on a chemical or physical non-viral transfection of cells in tissues and 3D cultures, discuss the advantages and remaining gaps, and propose future developments and applications.

The osteogenic and angiogenic potential of microRNA-26a delivered via a non-viral delivery peptide for bone repair

Bone-related injuries and diseases are among the most common causes of morbidity worldwide. Current bone-regenerative strategies such as auto- and allografts are invasive by nature, with adverse effects such as pain, infection and donor site morbidity. MicroRNA (miRNA) gene therapy has emerged as a promising area of research, with miRNAs capable of regulating multiple gene pathways simultaneously through the repression of post-transcriptional mRNAs. miR-26a is a key regulator of osteogenesis and has been found to be upregulated following bone injury, where it induces osteodifferentiation of mesenchymal stem cells (MSCs) and facilitates bone formation. This study demonstrates, for the first time, that the amphipathic, cell-penetrating peptide RALA can efficiently deliver miR-26a to MSCs in vitro to regulate osteogenic signalling. Transfection with miR-26a significantly increased expression of osteogenic and angiogenic markers at both gene and protein level. Using a rat calvarial defect model with a critical size defect, RALA/miR-26a NPs were delivered via an injectable, thermo-responsive Cs-g-PNIPAAm hydrogel to assess the impact on both rate and quality of bone healing. Critical defects treated with the RALA/miR-26a nanoparticles (NPs) had significantly increased bone volume and bone mineral density at 8 weeks, with increased blood vessel formation and mechanical properties. This study highlights the utility of RALA to deliver miR-26a for the purpose of bone healing within an injectable biomaterial, warranting further investigation of dose-related efficacy of the therapeutic across a range of in vivo models.

A Biomimetic, Bilayered Antimicrobial Collagen-Based Scaffold for Enhanced Healing of Complex Wound Conditions

Chronic, nonhealing wounds in the form of diabetic foot ulcers (DFUs) are a major complication for diabetic patients. The inability of a DFU to heal appropriately leads to an open wound with a high risk of infection. Current standards of care fail to fully address either the underlying defective wound repair mechanism or the risk of microbial infection. Thus, it is clear that novel approaches are needed. One such approach is the use of multifunctional biomaterials as platforms to direct and promote wound healing. In this study, a biomimetic, bilayered antimicrobial collagen-based scaffold was developed to deal with the etiology of DFUs. An epidermal, antimicrobial collagen/chitosan film for the prevention of wound infection was combined with a dermal collagen-glycosaminoglycan scaffold, which serves to support angiogenesis in the wound environment and ultimately accelerate wound healing. Biophysical and biological characterization identified an 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide cross-linked bilayered scaffold to have the highest structural stability with similar mechanical properties to products on the market, exhibiting a similar structure to native skin, successfully inhibiting the growth and infiltration of Staphylococcus aureus and supporting the proliferation of epidermal cells on its surface. This bilayered scaffold also demonstrated the ability to support the proliferation of key cell types involved in vascularization, namely, induced pluripotent stem cell derived endothelial cells and supporting stromal cells, with early signs of organization of these cells into vascular structures, showing great promise for the promotion of angiogenesis. Taken together, the results indicate that the bilayered scaffold is an excellent candidate for enhancement of diabetic wound healing by preventing wound infection and supporting angiogenesis.

Tissue Engineering-Based Strategies for Diabetic Foot Ulcer Management

Significance: Diabetic foot ulcers (DFU) are a mounting problem with the increasingly frail population. Injuries that would otherwise heal are kept open by risk factors such as diabetes, obesity, and age-related conditions, which interferes with the natural wound healing processes. Recent Advances: This review summarizes recent advancements in the field of tissue engineering for the treatment of DFUs. FDA-approved approaches, including signaling-based therapies, stem cell therapies, and skin substitutes are summarized and cutting-edge experimental technologies that have the potential to manage chronic wounds, such as skin printing, skin organogenesis, skin self-assembly, and prevascularization, are discussed. Critical Issues: The standard of care for chronic wounds involves wound debridement, wound dressings, and resolving the underlying cause such as lowering the glycemic index and reducing wound pressure. Current DFU treatments are limited by low wound closure rates and poor regrown skin quality. New adjuvant therapies that facilitate wound closure in place of or in conjunction with standard care are critically needed. Future Directions: Tissue engineering strategies are limited by the plasticity of adult human cells. In addition to traditional techniques, genetic modification, although currently an emerging technology, has the potential to unlock human regeneration and can be incorporated in future therapeutics.

Elastin-Derived VGVAPG Fragment Decorated Cell-Penetrating Peptide with Improved Gene Delivery Efficacy

Cell-penetrating peptides (CPPs) are attractive non-viral gene delivery vectors due to their high transfection capacity and safety. Previously, we have shown that cell-penetrating peptide RALA can be a promising gene delivery vector for chronic wound regeneration application. In this study, we engineered a novel peptide called RALA-E by introducing elastin-derived VGVAPG fragment into RALA, in order to target the elastin-binding protein on the cell surface and thus improve delivery efficacy of RALA. The transfection efficiency of RALA-E was evaluated by transfecting the HEK-293T and HeLa cell lines cells with RALA-E/pDNA complexes and the flow-cytometry results showed that RALA-E significantly increased the transfection efficiency by nearly 20% in both cell lines compared to RALA. Inhibition of pDNA transfection on HEK-293T cells via chlorpromazine, genistein and mβCD showed that the inhibition extent in transfection efficiency was much less for RALA-E group compared to RALA group. In addition, RALA-E/miR-146a complexes showed up to 90% uptake efficiency in macrophages, and can escape from the endosome and enter the nucleus to inhibit the expression of inflammation genes. Therefore, the developed RALA-E peptide has high potential as a safe and efficient vector for gene therapy application.

Mapping intellectual structure and research hotspots in the field of fibroblast-associated DFUs: a bibliometric analysis

Background

Diabetic foot ulcers (DFUs) are one of the most popular and severe complications of diabetes. The persistent non-healing of DFUs may eventually contribute to severe complications such as amputation, which presents patients with significant physical and psychological challenges. Fibroblasts are critical cells in wound healing and perform essential roles in all phases of wound healing. In diabetic foot patients, the disruption of fibroblast function exacerbates the non-healing of the wound. This study aimed to summarize the hotspots and evaluate the global research trends on fibroblast-related DFUs through bibliometric analysis.

Methods

Scientific publications on the study of fibroblast-related DFUs from January 1, 2000 to April 27, 2022 were retrieved from the Web of Science Core Collection (WoSCC). Biblioshiny software was primarily performed for the visual analysis of the literature, CiteSpace software and VOSviewer software were used to validate the results.

Results

A total of 479 articles on fibroblast-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were the USA, The Chinese University of Hong Kong, Wound Repair and Regeneration, and Seung-Kyu Han. In addition, keyword co-occurrence networks, historical direct citation networks, thematic map, and the trend topics map summarize the research hotspots and trends in this field.

Conclusion

Current studies indicated that research on fibroblast-related DFUs is attracting increasing concern and have clinical implications. The cellular and molecular mechanisms of the DFU pathophysiological process, the molecular mechanisms and therapeutic targets associated with DFUs angiogenesis, and the measures to promote DFUs wound healing are three worthy research hotspots in this field.

Macrophages as a therapeutic target to promote diabetic wound healing

It is well‏ ‏established that macrophages are key regulators of wound healing, displaying impressive plasticity and an evolving phenotype, from an aggressive pro-inflammatory or "M1" phenotype to a pro-healing or "M2" phenotype, depending on the wound healing stage, to ensure proper healing. Because dysregulated macrophage responses have been linked to impaired healing of diabetic wounds, macrophages are being considered as a therapeutic target for improved wound healing. In this review, we first discuss the role of macrophages in a normal skin wound healing process and discuss the aberrations that occur in macrophages under diabetic conditions. Next we provide an overview of recent macrophage-based therapeutic approaches, including delivery of ex-vivo-activated macrophages and delivery of pharmacological strategies aimed at eliminating or re-educating local skin macrophages. In particular, we focus on strategies to silence key regulator genes to repolarize wound macrophages to the M2 phenotype, and we provide a discussion of their potential future clinical translation.

Recent Progress in Development of Dressings Used for Diabetic Wounds with Special Emphasis on Scaffolds

Diabetic wound (DW) is a secondary application of uncontrolled diabetes and affects about 42.2% of diabetics. If the disease is left untreated/uncontrolled, then it may further lead to amputation of organs. In recent years, huge research has been done in the area of wound dressing to have a better maintenance of DW. These include gauze, films, foams or, hydrocolloid-based dressings as well as polysaccharide- and polymer-based dressings. In recent years, scaffolds have played major role as biomaterial for wound dressing due to its tissue regeneration properties as well as fluid absorption capacity. These are three-dimensional polymeric structures formed from polymers that help in tissue rejuvenation. These offer a large surface area to volume ratio to allow cell adhesion and exudate absorbing capacity and antibacterial properties. They also offer a better retention as well as sustained release of drugs that are directly impregnated to the scaffolds or the ones that are loaded in nanocarriers that are impregnated onto scaffolds. The present review comprehensively describes the pathogenesis of DW, various dressings that are used so far for DW, the limitation of currently used wound dressings, role of scaffolds in topical delivery of drugs, materials used for scaffold fabrication, and application of various polymer-based scaffolds for treating DW.

Leveraging Potential of Nanotherapeutics in Management of Diabetic Foot Ulcer

Diabetic foot ulcers (DFUs) are the most common complications associated with diabetes mellitus. DFUs are displayed as open sores or wounds located on the bottom of the foot as a secondary complication of diabetes mellitus (DM). DFUs are associated with significant morbidity and mortality and can subsequently lead to hospitalization and lower limb amputation if not recognized and treated on time. An immense challenge to conventional treatments is caused by the chronic nature of diabetic foot syndrome and it has led to the emergence of nanotechnology-based therapeutics. The greatest advantages of these nanotherapeutics are their unique biological, chemical, and physical properties. The present review highlights the augmentation of bacterial infections relating to delayed healing of DFUs and the potential of nanotherapeutics such as polymeric nanoparticles, metallic nanoparticles, siRNA-based nanoparticles, lipid nanoparticles, and nanofibers in accelerating wound healing in diabetic foot ulcers.

Nanotechnology-Assisted RNA Delivery: From Nucleic Acid Therapeutics to COVID-19 Vaccines

In recent years, the main quest of science has been the pioneering of the groundbreaking biomedical strategies needed for achieving a personalized medicine. Ribonucleic acids (RNAs) are outstanding bioactive macromolecules identified as pivotal actors in regulating a wide range of biochemical pathways. The ability to intimately control the cell fate and tissue activities makes RNA-based drugs the most fascinating family of bioactive agents. However, achieving a widespread application of RNA therapeutics in humans is still a challenging feat, due to both the instability of naked RNA and the presence of biological barriers aimed at hindering the entrance of RNA into cells. Recently, material scientists' enormous efforts have led to the development of various classes of nanostructured carriers customized to overcome these limitations. This work systematically reviews the current advances in developing the next generation of drugs based on nanotechnology-assisted RNA delivery. The features of the most used RNA molecules are presented, together with the development strategies and properties of nanostructured vehicles. Also provided is an in-depth overview of various therapeutic applications of the presented systems, including coronavirus disease vaccines and the newest trends in the field. Lastly, emerging challenges and future perspectives for nanotechnology-mediated RNA therapies are discussed.

Peptide-Assisted Nucleic Acid Delivery Systems on the Rise

Concerns associated with nanocarriers' therapeutic efficacy and side effects have led to the development of strategies to advance them into targeted and responsive delivery systems. Owing to their bioactivity and biocompatibility, peptides play a key role in these strategies and, thus, have been extensively studied in nanomedicine. Peptide-based nanocarriers, in particular, have burgeoned with advances in purely peptidic structures and in combinations of peptides, both native and modified, with polymers, lipids, and inorganic nanoparticles. In this review, we summarize advances on peptides promoting gene delivery systems. The efficacy of nucleic acid therapies largely depends on cell internalization and the delivery to subcellular organelles. Hence, the review focuses on nanocarriers where peptides are pivotal in ferrying nucleic acids to their site of action, with a special emphasis on peptides that assist anionic, water-soluble nucleic acids in crossing the membrane barriers they encounter on their way to efficient function. In a second part, we address how peptides advance nanoassembly delivery tools, such that they navigate delivery barriers and release their nucleic acid cargo at specific sites in a controlled fashion.

Development and Characterization of High Efficacy Cell-Penetrating Peptide via Modulation of the Histidine and Arginine Ratio for Gene Therapy

Cell-penetrating peptides (CPPs), as non-viral gene delivery vectors, are considered with lower immunogenic response, and safer and higher gene capacity than viral systems. In our previous study, a CPP peptide called RALA (arginine rich) presented desirable transfection efficacy and owns a potential clinic use. It is believed that histidine could enhance the endosome escaping ability of CPPs, yet RALA peptide contains only one histidine in each chain. In order to develop novel superior CPPs, by using RALA as a model, we designed a series of peptides named HALA (increased histidine ratio). Both plasmid DNA (pDNA) and siRNA transfection results on three cell lines revealed that the transfection efficacy is better when histidine replacements were on the C-terminal instead of on the N-terminal, and two histidine replacements are superior to three. By investigating the mechanism of endocytosis of the pDNA nanocomplexes, we discovered that there were multiple pathways that led to the process and caveolae played the main role. During the screening, we discovered a novel peptide-HALA2 of high cellular transfection efficacy, which may act as an exciting gene delivery vector for gene therapy. Our findings also bring new insights on the development of novel robust CPPs.

Peptide-Based Nanoparticles for Therapeutic Nucleic Acid Delivery

Gene therapy offers the possibility to skip, repair, or silence faulty genes or to stimulate the immune system to fight against disease by delivering therapeutic nucleic acids (NAs) to a patient. Compared to other drugs or protein treatments, NA-based therapies have the advantage of being a more universal approach to designing therapies because of the versatility of NA design. NAs (siRNA, pDNA, or mRNA) have great potential for therapeutic applications for an immense number of indications. However, the delivery of these exogenous NAs is still challenging and requires a specific delivery system. In this context, beside other non-viral vectors, cell-penetrating peptides (CPPs) gain more and more interest as delivery systems by forming a variety of nanocomplexes depending on the formulation conditions and the properties of the used CPPs/NAs. In this review, we attempt to cover the most important biophysical and biological aspects of non-viral peptide-based nanoparticles (PBNs) for therapeutic nucleic acid formulations as a delivery system. The most relevant peptides or peptide families forming PBNs in the presence of NAs described since 2015 will be presented. All these PBNs able to deliver NAs in vitro and in vivo have common features, which are characterized by defined formulation conditions in order to obtain PBNs from 60 nm to 150 nm with a homogeneous dispersity (PdI lower than 0.3) and a positive charge between +10 mV and +40 mV.

Layered Double Hydroxide as a Potent Non-viral Vector for Nucleic Acid Delivery Using Gene-Activated Scaffolds for Tissue Regeneration Applications

Nonviral vectors offer a safe alternative to viral vectors for gene therapy applications, albeit typically exhibiting lower transfection efficiencies. As a result, there remains a significant need for the development of a nonviral delivery system with low cytotoxicity and high transfection efficacy as a tool for safe and transient gene delivery. This study assesses MgAl-NO₃ layered double hydroxide (LDH) as a nonviral vector to deliver nucleic acids (pDNA, miRNA and siRNA) to mesenchymal stromal cells (MSCs) in 2D culture and using a 3D tissue engineering scaffold approach. Nanoparticles were formulated by complexing LDH with pDNA, microRNA (miRNA) mimics and inhibitors, and siRNA at varying mass ratios of LDH:nucleic acid. In 2D monolayer, pDNA delivery demonstrated significant cytotoxicity issues, and low cellular transfection was deemed to be a result of the poor physicochemical properties of the LDH–pDNA nanoparticles. However, the lower mass ratios required to successfully complex with miRNA and siRNA cargo allowed for efficient delivery to MSCs. Furthermore, incorporation of LDH–miRNA nanoparticles into collagen-nanohydroxyapatite scaffolds resulted in successful overexpression of miRNA in MSCs, demonstrating the development of an efficacious miRNA delivery platform for gene therapy applications in regenerative medicine.