Single subcutaneous administration of RGDK-lipopeptide:rhPDGF-B gene complex heals wounds in streptozotocin-induced diabetic rats

Therapeutic role of growth factors in treating diabetic wound

Wounds in diabetic patients, especially diabetic foot ulcers, are more difficult to heal compared with normal wounds and can easily deteriorate, leading to amputation. Common treatments cannot heal diabetic wounds or control their many complications. Growth factors are found to play important roles in regulating complex diabetic wound healing. Different growth factors such as transforming growth factor beta 1, insulin-like growth factor, and vascular endothelial growth factor play different roles in diabetic wound healing. This implies that a therapeutic modality modulating different growth factors to suit wound healing can significantly improve the treatment of diabetic wounds. Further, some current treatments have been shown to promote the healing of diabetic wounds by modulating specific growth factors. The purpose of this study was to discuss the role played by each growth factor in therapeutic approaches so as to stimulate further therapeutic thinking.

Gene therapy to enhance angiogenesis in chronic wounds

Skin injuries and chronic non-healing wounds are one of the major global burdens on the healthcare systems worldwide due to their difficult-to-treat nature, associated co-morbidities, and high health care costs. Angiogenesis has a pivotal role in the wound-healing process, which becomes impaired in many chronic non-healing wounds, leading to several healing disorders and complications. Therefore, induction or promotion of angiogenesis can be considered a promising approach for healing of chronic wounds. Gene therapy is one of the most promising upcoming strategies for the treatment of chronic wounds. It can be classified into three main approaches: gene augmentation, gene silencing, and gene editing. Despite the increasing number of encouraging results obtained using nucleic acids (NAs) as active pharmaceutical ingredients of gene therapy, efficient delivery of NAs to their site of action (cytoplasm or nucleus) remains a key challenge. Selection of the right therapeutic cargo and delivery methods is crucial for a favorable prognosis of the healing process. This article presents an overview of gene therapy and non-viral delivery methods for angiogenesis induction in chronic wounds.

Exploration of Lipid-Based Nanocarriers as Drug Delivery Systems in Diabetic Foot Ulcer

Diabetes mellitus is a chronic manifestation characterized by high levels of glucose in the blood resulting in several complications including diabetic wounds and ulcers, which predominantly require a longer duration of treatment and adversely affect the quality of life of the patients. Nanotechnology-based therapeutics (both intrinsic and extrinsic types) have emerged as a promising treatment in diabetic foot ulcer/chronic wounds owing to their unique characteristics and specific functional properties. In this review, we have focused on the significance of the use of lipids in the healing of diabetic ulcers, their interaction with the injured skin, and recent trends in lipid-based nanocarriers for the healing of diabetic wounds. Lipid nanocarriers are also being investigated for gene therapy in diabetic wound healing to encapsulate nucleic acids such as siRNA and miRNA, which could silence the expression of inflammatory cytokines overexpressed in chronic wounds. Additionally, these are also being explored for encapsulating proteins, peptides, growth factors, and other biological genetic material as therapeutic agents. Lipid-based nanocarriers encompassing a wide variety of carriers such as liposomes, niosomes, ethosomes, solid lipid nanoparticles, and lipidoid nanoparticles that are explored for the treatment of foot ulcers supplemented with relevant research studies have been discussed in the present review. Lipid-based nanodrug delivery systems have demonstrated promising wound healing potential, particularly in diabetic conditions due to the enhanced efficacy of the entrapped active molecules.

Nanotechnology Approaches in Chronic Wound Healing

Significance: The incidence of chronic wounds is increasing due to our aging population and the augment of people afflicted with diabetes. With the extended knowledge on the biological mechanisms underlying these diseases, there is a novel influx of medical technologies into the conventional wound care market. Recent Advances: Several nanotechnologies have been developed demonstrating unique characteristics that address specific problems related to wound repair mechanisms. In this review, we focus on the most recently developed nanotechnology-based therapeutic agents and evaluate the efficacy of each treatment in in vivo diabetic models of chronic wound healing. Critical Issues: Despite the development of potential biomaterials and nanotechnology-based applications for wound healing, this scientific knowledge is not translated into an increase of commercially available wound healing products containing nanomaterials. Future Directions: Further studies are critical to provide insights into how scientific evidences from nanotechnology-based therapies can be applied in the clinical setting.

Innovations in gene and growth factor delivery systems for diabetic wound healing

The rise in lower extremity amputations due to nonhealing of foot ulcers in diabetic patients calls for rapid improvement in effective treatment regimens. Administration of growth factors (GFs) are thought to offer an off-the-shelf treatment; however, the dose- and time-dependent efficacy of the GFs together with the hostile environment of diabetic wound beds impose a major hindrance in the selection of an ideal route for GF delivery. As an alternative, the delivery of therapeutic genes using viral and nonviral vectors, capable of transiently expressing the genes until the recovery of the wounded tissue offers promise. The development of implantable biomaterial dressings capable of modulating the release of either single or combinatorial GFs/genes may offer solutions to this overgrowing problem. This article reviews the state of the art on gene and protein delivery and the strategic optimization of clinically adopted delivery strategies for the healing of diabetic wounds.

Integrin Regulation of Epidermal Functions in Wounds

Significance: Integrins are bidirectional signaling receptors for extracellular matrix that regulate both inside-out signaling that controls keratinocyte-mediated changes to the wound microenvironment and outside-in signaling that controls keratinocyte responses to microenvironmental changes. As such, integrins represent attractive therapeutic targets for treatment of chronic wounds or general promotion of wound healing. Advances in wound management are particularly important as the elderly and diabetic populations within the United States continue to grow. Recent Advances: Although integrins are best known for mediating cell adhesion and migration, integrins in wound epidermis also control cell survival, proliferation, matrix remodeling, and paracrine crosstalk to other cellular compartments of the wound. Importantly, the concept of targeting integrins in the clinic has been established for treatment of certain cancers and other diseases, laying the groundwork for similar exploitation of integrins as targets to treat chronic wounds. Critical Issues: Despite their attractiveness as therapeutic targets, integrins have complex roles in wound healing that are impacted by both their own expression and a highly dynamic wound microenvironment that determines ligand availability. Therefore, identifying relevant integrin ligands in the wound and understanding both distinct and overlapping functions that different integrins play in the epidermis will be critical to determine their precise roles in wound healing. Future Directions: Future research should focus on gaining a thorough understanding of the highly coordinated functions of different integrins in wound epidermis, and on determining which of these functions go awry in pathological wounds. This focus should facilitate development of integrin-targeting therapeutics for treating chronic wounds.

Epithelial-mesenchymal transition-derived cells exhibit multilineage differentiation potential similar to mesenchymal stem cells

The epithelial-to-mesenchymal transition (EMT) is an embryonic process that becomes latent in most normal adult tissues. Recently, we have shown that induction of EMT endows breast epithelial cells with stem cell traits. In this report, we have further characterized the EMT-derived cells and shown that these cells are similar to mesenchymal stem cells (MSCs) with the capacity to differentiate into multiple tissue lineages. For this purpose, we induced EMT by ectopic expression of Twist, Snail, or transforming growth factor-beta in immortalized human mammary epithelial cells. We found that the EMT-derived cells and MSCs share many properties including the antigenic profile typical of MSCs, that is, CD44(+), CD24(-), and CD45(-). Conversely, MSCs express EMT-associated genes, such as Twist, Snail, and mesenchyme forkhead 1 (FOXC2). Interestingly, CD140b (platelet-derived growth factor receptor-beta), a marker for naive MSCs, is exclusively expressed in EMT-derived cells and not in their epithelial counterparts. Moreover, functional analyses revealed that EMT-derived cells but not the control cells can differentiate into alizarin red S-positive mature osteoblasts, oil red O-positive adipocytes and alcian blue-positive chondrocytes similar to MSCs. We also observed that EMT-derived cells but not the control cells invade and migrate towards MDA-MB-231 breast cancer cells similar to MSCs. In vivo wound homing assays in nude mice revealed that the EMT-derived cells home to wound sites similar to MSCs. In conclusion, we have demonstrated that the EMT-derived cells are similar to MSCs in gene expression, multilineage differentiation, and ability to migrate towards tumor cells and wound sites.

Integrin targeted drug and gene delivery

IMPORTANCE OF THE FIELD

Recently, there has been substantial progress in the development of integrin targeted pharmaceuticals and drug delivery systems. Integrin is an important member in the cell adhesion molecule family, which is involved in regulation of complex biological conditions, from keeping normal physiological activities to causing cellular dysfunction in diseased cells. Hence, it is timely to summarize the recent developments in integrin targeted drug and gene delivery systems to understand better their advantages and limitations.

AREAS COVERED IN THIS REVIEW

In this review, advances in the discovery and clinical trials of these integrin antagonists against different integrin subunits are summarized and discussed. Besides using integrin inhibitor as a single therapeutic agent, integrin antagonists that were conjugated to cytotoxic drugs by synthetic chemistry or coupled to biomacromolecules by either DNA recombination technology or fusion protein technology for integrin targeted therapy have been explored. Furthermore, nanoparticles with integrin targeting ligands for both drug and gene delivery, typically for antiangiogenesis and anticancer therapy, are highlighted and evaluated.

WHAT THE READER WILL GAIN

This review sheds light on the future development of integrin targeted drug and/or gene delivery systems.

TAKE HOME MESSAGE

Although thus far there are still limitations, integrin targeted delivery systems have already shown their potential as important pharmaceuticals in the near future.

Cationic amphiphiles: promising carriers of genetic materials in gene therapy

The clinical success of gene therapy critically depends on the use of efficient and safe gene delivery reagents. The present tutorial review is aimed at inspiring young researchers and students to take up the unsolved challenges in using cationic amphiphiles as safe gene transfer reagents. The review highlights important structure-activity studies in the field to date including the use of cationic amphiphiles for receptor specific targeted gene therapy and for delivery of siRNAs in the emerging field of RNA interference.