Nanoparticle-mediated gene silencing confers radioprotection to salivary glands in vivo

Epigenetic Modulations of Non-Coding RNAs: A Novel Therapeutic Perspective in Sjӧgren's Syndrome

Sjögren's syndrome (SS) is an autoimmune disease that can be classified as an epithelitis based on the immune-mediated attack directed specifically at epithelial cells. SS predominantly affects women, is characterized by the production of highly specific circulating autoantibodies, and the major targets are the salivary and lachrymal glands. Although a genetic predisposition has been amply demonstrated for SS, the etiology remains unclear. The recent integration of epigenetic data relating to autoimmune diseases opens new therapeutic perspectives based on a better understanding of the molecular processes implicated. In the autoimmune field, non-coding RNA molecules (nc-RNA), which regulate gene expression by binding to mRNAs and could have a therapeutic value, have aroused great interest. The focus of this review is to summarize the biological functions of nc-RNAs in the pathogenesis of SS and decode molecular pathways implicated in the disease, in order to identify new therapeutic strategies.

Platelet membrane biomimetic nanoparticle-targeted delivery of TGF-β1 siRNA attenuates renal inflammation and fibrosis

The progression of renal fibrosis to end-stage renal disease (ESRD) is significantly influenced by transforming growth factor-beta (TGF-beta) signal pathway. This study aimed to develop nanoparticles (PMVs@PLGA complexes) with platelet membrane camouflage, which can transport interfering RNA to target and regulate the TGF-β1 pathway in damaged renal tissues. The aim is to reduce the severity of acute kidney injury and to reduce fibrosis in chronic kidney disease. Hence, we formulated PMVs@TGF-β1-siRNA NP complexes and employed them for both in vitro and in vivo therapy. From the experimental findings we know that the PMVs@siRNA NPs could effectively target the kidneys in unilateral ureteral obstruction (UUO) mice and ischemia/reperfusion injury (I/R) mice. In animal models of treatment, PMVs@siRNA NP complexes effectively decreased the expression of TGF-β1 and mitigated inflammation and fibrosis in the kidneys by blocking the TGF-β1/Smad3 pathway. Therefore, these PMVs@siRNA NP complexes can serve as a promising biological delivery system for treating kidney diseases.

Biomaterials-mediated radiation-induced diseases treatment and radiation protection

In recent years, the intersection of the academic and medical domains has increasingly spotlighted the utilization of biomaterials in radioactive disease treatment and radiation protection. Biomaterials, distinguished from conventional molecular pharmaceuticals, offer a suite of advantages in addressing radiological conditions. These include their superior biological activity, chemical stability, exceptional histocompatibility, and targeted delivery capabilities. This review comprehensively delineates the therapeutic mechanisms employed by various biomaterials in treating radiological afflictions impacting the skin, lungs, gastrointestinal tract, and hematopoietic systems. Significantly, these nanomaterials function not only as efficient drug delivery vehicles but also as protective agents against radiation, mitigating its detrimental effects on the human body. Notably, the strategic amalgamation of specific biomaterials with particular pharmacological agents can lead to a synergistic therapeutic outcome, opening new avenues in the treatment of radiation- induced diseases. However, despite their broad potential applications, the biosafety and clinical efficacy of these biomaterials still require in-depth research and investigation. Ultimately, this review aims to not only bridge the current knowledge gaps in the application of biomaterials for radiation-induced diseases but also to inspire future innovations and research directions in this rapidly evolving field.

Salivary Gland Bioengineering

Salivary gland dysfunction affects millions globally, and tissue engineering may provide a promising therapeutic avenue. This review delves into the current state of salivary gland tissue engineering research, starting with a study of normal salivary gland development and function. It discusses the impact of fibrosis and cellular senescence on salivary gland pathologies. A diverse range of cells suitable for tissue engineering including cell lines, primary salivary gland cells, and stem cells are examined. Moreover, the paper explores various supportive biomaterials and scaffold fabrication methodologies that enhance salivary gland cell survival, differentiation, and engraftment. Innovative engineering strategies for the improvement of vascularization, innervation, and engraftment of engineered salivary gland tissue, including bioprinting, microfluidic hydrogels, mesh electronics, and nanoparticles, are also evaluated. This review underscores the promising potential of this research field for the treatment of salivary gland dysfunction and suggests directions for future exploration.

Biomimetic nanoparticles of platelet membranes carrying bFGF and VEGFA genes promote deep burn wound healing

INTRODUCTION

The treatment of burn wounds, especially deep burn wounds, remains a major clinical challenge. Growth factors such as basic fibroblast growth factor (bFGF) and vascular endothelial growth factor A (VEGFA) show great potential in promoting the healing of damaged tissues. This study explored wound healing following targeted delivery of bFGF and VEGFA genes into deep burn wounds through a novel platelet membrane-coated nanoparticle (PM@gene-NP) complex delivery system.

METHODS

First, bFGF and VEGFA genes were inserted into plasmid (pEGFP-N1) vectors. Subsequently, the assembled plasmids were loaded onto nanoparticles to form gene-loaded nanoparticle complexes, which were then wrapped with extracted platelet membrane, fully simulating the characteristics of platelets, in order to actively target sites of inflammatory damage. After administration of PM@gene-NP complexes through the tail vein of rats, a series of experiments were conducted to evaluate wound healing.

RESULTS

The PM@gene-NP complexes effectively targeted the burn sites. After the administration of the PM@gene-NP complexes, the rats exhibited increased blood flow in the burn wounds, which also healed faster than control groups. Histological results showed fewer inflammatory cells in the burned skin tissue after treatment. After the wounds healed, the production of hair follicles, sebaceous glands and other skin accessories in the skin tissue increased.

CONCLUSION

Our results showed that the PM@gene-NP complexes can effectively deliver gene therapy to the injured area, and this delivery system should be considered as a potential method for treating deep burns.

Metabolomics analysis of pathways underlying radiation-induced salivary gland dysfunction stages

Salivary gland hypofunction is an adverse side effect associated with radiotherapy for head and neck cancer patients. This study delineated metabolic changes at acute, intermediate, and chronic radiation damage response stages in mouse salivary glands following a single 5 Gy dose. Ultra-high performance liquid chromatography-mass spectrometry was performed on parotid salivary gland tissue collected at 3, 14, and 30 days following radiation (IR). Pathway enrichment analysis, network analysis based on metabolite structural similarity, and network analysis based on metabolite abundance correlations were used to incorporate both metabolite levels and structural annotation. The greatest number of enriched pathways are observed at 3 days and the lowest at 30 days following radiation. Amino acid metabolism pathways, glutathione metabolism, and central carbon metabolism in cancer are enriched at all radiation time points across different analytical methods. This study suggests that glutathione and central carbon metabolism in cancer may be important pathways in the unresolved effect of radiation treatment.

Metabolic reprogramming contributes to radioprotection by protein kinase Cδ

Loss of protein kinase Cδ (PKCδ) activity renders cells resistant to DNA damaging agents, including irradiation; however, the mechanism(s) underlying resistance is poorly understood. Here, we have asked if metabolic reprogramming by PKCδ contributes to radioprotection. Analysis of global metabolomics showed that depletion of PKCδ affects metabolic pathways that control energy production and antioxidant, nucleotide, and amino acid biosynthesis. Increased NADPH and nucleotide production in PKCδ-depleted cells is associated with upregulation of the pentose phosphate pathway (PPP) as evidenced by increased activation of G6PD and an increase in the nucleotide precursor, 5-phosphoribosyl-1-pyrophosphate. Stable isotope tracing with U-[13C6] glucose showed reduced utilization of glucose for glycolysis in PKCδ-depleted cells and no increase in U-[13C6] glucose incorporation into purines or pyrimidines. In contrast, isotope tracing with [13C5, 15N2] glutamine showed increased utilization of glutamine for synthesis of nucleotides, glutathione, and tricarboxylic acid intermediates and increased incorporation of labeled glutamine into pyruvate and lactate. Using a glycolytic rate assay, we confirmed that anaerobic glycolysis is increased in PKCδ-depleted cells; this was accompanied by a reduction in oxidative phosphorylation, as assayed using a mitochondrial stress assay. Importantly, pretreatment of cells with specific inhibitors of the PPP or glutaminase prior to irradiation reversed radioprotection in PKCδ-depleted cells, indicating that these cells have acquired codependency on the PPP and glutamine for survival. Our studies demonstrate that metabolic reprogramming to increase utilization of glutamine and nucleotide synthesis contributes to radioprotection in the context of PKCδ inhibition.

Identifying novel radioprotective drugs via salivary gland tissue chip screening

During head and neck cancer treatment, off-target ionizing radiation damage to the salivary glands commonly causes a permanent loss of secretory function. Due to the resulting decrease in saliva production, patients have trouble eating, speaking and are predisposed to oral infections and tooth decay. While the radioprotective antioxidant drug Amifostine is FDA approved to prevent radiation-induced hyposalivation, it has intolerable side effects that limit its use, motivating the discovery of alternative therapeutics. To address this issue, we previously developed a salivary gland mimetic (SGm) tissue chip platform. Here, we leverage this SGm tissue chip for high-content drug discovery. First, we developed in-chip assays to quantify glutathione and cellular senescence (β-galactosidase), which are biomarkers of radiation damage, and we validated radioprotection using WR-1065, the active form of Amifostine. Other reported radioprotective drugs including Edaravone, Tempol, N-acetylcysteine (NAC), Rapamycin, Ex-Rad, and Palifermin were also tested to validate the ability of the assays to detect cell damage and radioprotection. All of the drugs except NAC and Ex-Rad exhibited robust radioprotection. Next, a Selleck Chemicals library of 438 FDA-approved drugs was screened for radioprotection. We discovered 25 hits, with most of the drugs identified exhibiting mechanisms of action other than antioxidant activity. Hits were down-selected using EC50 values and pharmacokinetic and pharmacodynamic data from the PubChem database. This led us to test Phenylbutazone (anti-inflammatory), Enoxacin (antibiotic), and Doripenem (antibiotic) for in vivo radioprotection in mice using retroductal injections. Results confirm that Phenylbutazone and Enoxacin exhibited radioprotection equivalent to Amifostine. This body of work demonstrates the development and validation of assays using a SGm tissue chip platform for high-content drug screening and the successful in vitro discovery and in vivo validation of novel radioprotective drugs with non-antioxidant primary indications pointing to possible, yet unknown novel mechanisms of radioprotection.

Identifying novel radioprotective drugs via salivary gland tissue chip screening

During head and neck cancer treatment, off-target ionizing radiation damage to the salivary glands commonly causes a permanent loss of secretory function. Due to the resulting decrease in saliva production, patients have trouble eating, speaking and are predisposed to oral infections and tooth decay. While the radioprotective antioxidant drug Amifostine is approved to prevent radiation-induced hyposalivation, it has intolerable side effects that limit its use, motivating the discovery of alternative therapeutics. To address this issue, we previously developed a salivary gland mimetic (SGm) tissue chip platform. Here, we leverage this SGm tissue chip for high-content drug discovery. First, we developed in-chip assays to quantify glutathione and cellular senescence (β-galactosidase), which are biomarkers of radiation damage, and we validated radioprotection using WR-1065, the active form of Amifostine. Following validation, we tested other reported radioprotective drugs, including, Edaravone, Tempol, N-acetylcysteine (NAC), Rapamycin, Ex-Rad, and Palifermin, confirming that all drugs but NAC and Ex-Rad exhibited robust radioprotection. Next, a Selleck Chemicals library of 438 FDA-approved drugs was screened for radioprotection. We discovered 25 hits, with most of the drugs identified with mechanisms of action other than antioxidant activity. Hits were down-selected using EC 50 values and pharmacokinetics and pharmacodynamics data from the PubChem database leading to testing of Phenylbutazone (anti-inflammatory), Enoxacin (antibiotic), and Doripenem (antibiotic) for in vivo radioprotection in mice using retroductal injections. Results confirm that Phenylbutazone and Enoxacin exhibited equivalent radioprotection to Amifostine. This body of work demonstrates the development and validation of assays using a SGm tissue chip platform for high-content drug screening and the successful in vitro discovery and in vivo validation of novel radioprotective drugs with nonantioxidant primary indications pointing to possible, yet unknown novel mechanisms of radioprotection.

Effect of nanoparticle-mediated delivery of SFRP4 siRNA for treating Dupuytren disease

Dupuytren disease (DD) is a progressive fibrous proliferative disease. It invades the palmar aponeurosis and extends to the finger fascia, eventually leading to flexion contracture of the metacarpophalangeal or interphalangeal joint. At present, surgical resection and the local injection of collagenase are the main methods for the treatment of DD, but postoperative complications and high recurrence rates often occur. Bioinformatics analysis showed that the increased expression of SFRP4 protein was closely related to the incidence of DD. Persistent and effective inhibition of SFRP4 expression may be a promising treatment for DD. We prepared SFRP4 siRNA/nanoparticle complexes (si-SFRP4) and negative siRNA/nanoparticle complexes (NC) and applied them in vitro and in vivo. Flow cytometry analysis showed that si-SFRP4 could be successfully transfected into DD cells. MTT and EdU staining assays showed that the OD values and percentage of EdU-positive cells in the si-SFRP4 group were significantly lower than those in the NC group. Scratch tests showed that the wound healing rate of the si-SFRP4 group was lower than that of the NC group, and the difference was statistically significant. The expression of SFRP4 and α-SMA protein in the si-SFRP4 group significantly decreased in both DD cells and xenografts. Compared with the NC group, the xenograft quality of the si-SFRP4 group was significantly reduced. Masson's trichrome staining showed that the collagen and fibrous cells in the si-SFRP4 group were more uniform, slender, parallel and regular. The above experimental results suggest that the proliferation and metabolism of palmar aponeurosis cells and the quality of metacarpal fascia xenografts were both significantly decreased. We speculated that nanoparticle-mediated SFRP4 siRNA can be used as a potential new method for the treatment of DD.

Gene Therapeutic Delivery to the Salivary Glands

The salivary glands, exocrine glands in our body producing saliva, can be easily damaged by various factors. Radiation therapy and Sjogren's syndrome (a systemic autoimmune disease) are the two main causes of salivary gland damage, leading to a severe reduction in patients' quality of life. Gene transfer to the salivary glands has been considered a promising approach to treating the dysfunction. Gene therapy has long been applied to cure multiple diseases, including cancers, and hereditary and infectious diseases, which are proven to be safe and effective for the well-being of patients. The application of this treatment on salivary gland injuries has been studied for decades, yet its clinical progress is delayed. This chapter provides a coup d'oeil into gene transfer methods and various gene/vector types for salivary glands to help the new scientists and update established scientists on the progress that has been made during the past decades for the treatment of salivary gland disorders.

Identification of nanoparticle-mediated siRNA-ASPN as a key gene target in the treatment of keloids

Background: Keloid, also known as connective tissue hyperplasia, is a benign proliferative disorder with a global distribution. The available therapeutic interventions are steroid injections, surgical removal of keloids, radiotherapy, compression therapy, the application of cryosurgery, and many other methods.

Objectives: Existing treatments or approaches for keloids may lead to similar or even larger lesions at the site of keloid excision, leading to a high recurrence rate. Therefore, this study aims at identifying a new gene-based therapy for the treatment of keloids.

Methods: An ASPN-siRNA/nanoparticle combination (si-ASPN) and a negative siRNA/nanoparticle complex (NC) was developed on the basis of bioinformatics studies and used in vitro and in vivo experiments.

Results: The results showed a strong correlation between the development of keloids and high expression of ASPN protein. With the expression of ASPN protein greatly reduced in keloid fibroblasts and nude mice allografts after treatment with si-ASPN, the collagen and fibroblasts were also uniform, thinner, parallel and regular.

Conclusion: All the above experimental results suggest that keloid and ASPN are closely related and both fibroblast growth and metabolism of keloid are inhibited after silencing ASPN. Therefore, ASPN-siRNA delivered via nanoparticles can serve as a novel intervention therapy for the treatment of keloids.

Platelet membrane-camouflaged nanoparticles carry microRNA inhibitor against myocardial ischaemia‒reperfusion injury

The incidence of myocardial ischaemia‒reperfusion injury (MIRI) is increasing every year, and there is an urgent need to develop new therapeutic approaches. Nrf2 is thought to play a protective role during MIRI and it is regulated by microRNAs (miRNAs). This study focused on PLGA nanoparticles camouflaged by platelet membrane vesicles (PMVs) (i.e., PMVs@PLGA complexes) carrying microRNA inhibitors, which regulate Nrf2 and can play a therapeutic role in the MIRI process. In vitro and in vivo characterization showed that PMVs@PLGA has excellent transfection efficiency, low toxicity and good targeting. MicroRNAs that effectively regulate Nrf2 were identified, and then PMVs@PLGA-miRNA complexes were prepared and used for in vitro and in vivo treatment. PMVs@PLGA-miRNA complexes can effectively target the delivery of inhibitors to cardiomyocytes. Our results suggest that PMVs@PLGA complexes are a novel delivery system and a novel biological approach to the treatment of MIRI.

Salivary gland function, development, and regeneration

Salivary glands produce and secrete saliva, which is essential for maintaining oral health and overall health. Understanding both the unique structure and physiological function of salivary glands, as well as how they are affected by disease and injury, will direct the development of therapy to repair and regenerate them. Significant recent advances, particularly in the OMICS field, increase our understanding of how salivary glands develop at the cellular, molecular, and genetic levels: the signaling pathways involved, the dynamics of progenitor cell lineages in development, homeostasis, and regeneration, and the role of the extracellular matrix microenvironment. These provide a template for cell and gene therapies as well as bioengineering approaches to repair or regenerate salivary function.

Possible radioprotection of submandibular glands in gamma-irradiated rats using kaempferol: a histopathological and immunohistochemical study

BACKGROUND AND PURPOSE

Salivary gland damage remains a problem despite advances in radiotherapy schedules for head and neck cancer. Kaempferol, a natural flavonoid, found in several fruits and vegetables, is a good antioxidant. This study was designed to evaluate the possible protective effects of kaempferol on submandibular glands (SMGs) of rats exposed to fractionated gamma irradiation.

MATERIALS AND METHODS

Twenty-four male adult Wistar albino rats were included in this study and assigned to three groups (n = 8). Rats in group K received kaempferol orally in five doses at a dose of 10 mg/kg/2 days for 10 days. Meanwhile, rats in group R were subjected to fractionated whole-body gamma irradiation at a dose of 2 Gy/5 days/week for 2 weeks (20 Gy), and the KR group received kaempferol as group K and then was subjected to a fractionated whole-body gamma irradiation as group R. SMG samples were collected on days 1 and 7 after the last radiation session; and processed for histopathological and immunohistochemical investigations.

RESULTS

The SMGs of group R showed focal atrophy and degeneration. Acini showed vacuolization and had pyknotic hyperchromatic nuclei. Striated ducts degenerated, shrunken, and were surrounded by empty spaces. The percentage of areas covered by cyclooxygenase-2 (COX-2) significantly increased, whereas the percentage of areas covered by proliferating cell nuclear antigen (PCNA) significantly decreased compared with those in group K. Cotreatment with kaempferol (group KR) partially preserved normal gland architecture where acinar vacuolation and degeneration were almost absent; however, some ducts degenerated. A significant decrease in the percentage of areas covered by COX-2 and a significant increase in the percentage of areas covered by PCNA were observed compared with those in group R.

CONCLUSIONS

Kaempferol has a possible radioprotective effect on the SMGs of rats exposed to fractionated gamma irradiation.

PKCα and PKCδ: Friends and Rivals

PKC comprises a large family of serine/threonine kinases that share a requirement for allosteric activation by lipids. While PKC isoforms have significant homology, functional divergence is evident among subfamilies and between individual PKC isoforms within a subfamily. Here, we highlight these differences by comparing the regulation and function of representative PKC isoforms from the conventional (PKCα) and novel (PKCδ) subfamilies. We discuss how unique structural features of PKCα and PKCδ underlie differences in activation and highlight the similar, divergent, and even opposing biological functions of these kinases. We also consider how PKCα and PKCδ can contribute to pathophysiological conditions and discuss challenges to targeting these kinases therapeutically.

Insights into Nanomedicine for Head and Neck Cancer Diagnosis and Treatment

Head and neck cancers rank sixth among the most common cancers today, and the survival rate has remained virtually unchanged over the past 25 years, due to late diagnosis and ineffective treatments. They have two main risk factors, tobacco and alcohol, and human papillomavirus infection is a secondary risk factor. These cancers affect areas of the body that are fundamental for the five senses. Therefore, it is necessary to treat them effectively and non-invasively as early as possible, in order to do not compromise vital functions, which is not always possible with conventional treatments (chemotherapy or radiotherapy). In this sense, nanomedicine plays a key role in the treatment and diagnosis of head and neck cancers. Nanomedicine involves using nanocarriers to deliver drugs to sites of action and reducing the necessary doses and possible side effects. The main purpose of this review is to give an overview of the applications of nanocarrier systems to the diagnosis and treatment of head and neck cancer. Herein, several types of delivery strategies, radiation enhancement, inside-out hyperthermia, and theragnostic approaches are addressed.

Development of nanotechnology-mediated precision radiotherapy for anti-metastasis and radioprotection

Radiotherapy (RT), including external beam RT and internal radiation therapy, uses high-energy ionizing radiation to kill tumor cells.

Pharmacological Activation of cGAS for Cancer Immunotherapy

When compartmentally mislocalized within cells, nucleic acids can be exceptionally immunostimulatory and can even trigger the immune-mediated elimination of cancer. Specifically, the accumulation of double-stranded DNA in the cytosol can efficiently promote antitumor immunity by activating the cGAMP synthase (cGAS) / stimulator of interferon genes (STING) cellular signaling pathway. Targeting this cytosolic DNA sensing pathway with interferon stimulatory DNA (ISD) is therefore an attractive immunotherapeutic strategy for the treatment of cancer. However, the therapeutic activity of ISD is limited by several drug delivery barriers, including susceptibility to deoxyribonuclease degradation, poor cellular uptake, and inefficient cytosolic delivery. Here, we describe the development of a nucleic acid immunotherapeutic, NanoISD, which overcomes critical delivery barriers that limit the activity of ISD and thereby promotes antitumor immunity through the pharmacological activation of cGAS at the forefront of the STING pathway. NanoISD is a nanoparticle formulation that has been engineered to confer deoxyribonuclease resistance, enhance cellular uptake, and promote endosomal escape of ISD into the cytosol, resulting in potent activation of the STING pathway via cGAS. NanoISD mediates the local production of proinflammatory cytokines via STING signaling. Accordingly, the intratumoral administration of NanoISD induces the infiltration of natural killer cells and T lymphocytes into murine tumors. The therapeutic efficacy of NanoISD is demonstrated in preclinical tumor models by attenuated tumor growth, prolonged survival, and an improved response to immune checkpoint blockade therapy.

Laminin-1 Peptides Conjugated to Fibrin Hydrogels Promote Salivary Gland Regeneration in Irradiated Mouse Submandibular Glands

Previous studies demonstrated that salivary gland morphogenesis and differentiation are enhanced by modification of fibrin hydrogels chemically conjugated to Laminin-1 peptides. Specifically, Laminin-1 peptides (A99: CGGALRGDN-amide and YIGSR: CGGADPGYIGSRGAA-amide) chemically conjugated to fibrin promoted formation of newly organized salivary epithelium both in vitro (e.g., using organoids) and in vivo (e.g., in a wounded mouse model). While these studies were successful, the model's usefulness for inducing regenerative patterns after radiation therapy remains unknown. Therefore, the goal of the current study was to determine whether transdermal injection with the Laminin-1 peptides A99 and YIGSR chemically conjugated to fibrin hydrogels promotes tissue regeneration in irradiated salivary glands. Results indicate that A99 and YIGSR chemically conjugated to fibrin hydrogels promote formation of functional salivary tissue when transdermally injected to irradiated salivary glands. In contrast, when left untreated, irradiated salivary glands display a loss in structure and functionality. Together, these studies indicate that fibrin hydrogel-based implantable scaffolds containing Laminin-1 peptides promote secretory function of irradiated salivary glands.

Effects of nanoparticle-mediated Co-delivery of bFGF and VEGFA genes to deep burn wounds: An in vivo study

Deep burns are a common form of trauma worldwide, and they are hard to be cured in a short time and enhance psychological pressure of the patients. How to effectively promote the healing of wounds after burns is a continuing challenge currently faced by burn physicians. Various strategies of promoting wound healing of deep burns have been developed, including gene therapy and growth factor therapy. In this study, we developed a combined therapy using PLGA nanoparticles as carriers to deliver bFGF and VEGFA genes to promote healing of burn wounds. We first inserted the bFGF and VEGFA genes into pEGFP-N1 vectors and loaded the mixed generated plasmids into PLGA nanoparticles. Next, we injected the nanoparticle/plasmid complexes into the rats intracutaneously and found that the complexes were successfully transfected in vivo one week later. Finally, we injected the nanoparticle/plasmid complexes containing bFGF and VEGFA around burn wounds. We found that the percentage of wound healing of rats treated with nanoparticles/bFGF+ VEGFA plasmid complexes was higher than that of rats in the scald control group, and the early percentage of wound complete epithelialization was also higher. Therefore, combining gene therapy with nanoparticles may be an effective biological strategy for wound repair.

Retroductal Delivery of Epidermal Growth Factor Protects Salivary Progenitors after Irradiation

Salivary gland hypofunction after irradiation is associated with a deficit of epithelial stem/progenitors in salivary glands. Although epidermal growth factor (EGF) is known to stimulate the proliferation of epithelial cells, the therapeutic effect of EGF on salivary epithelial stem/progenitors remains undetermined. In this study, we administered EGF to submandibular glands (SMGs) via a retrograde route through the SMG excretory duct before fractionated irradiation and examined whether EGF could protect salivary epithelial progenitor cells from radiation and alleviate radiation-induced salivary hypofunction. EGF-treated mice exhibited greater body and gland weights at 12 wk after irradiation than untreated mice. The retroductal delivery of EGF improved salivary secretory function and increased salivary amylase activity in a dose-dependent manner. Histological examinations highlighted the amelioration of the loss of keratine-14⁺ (KRT14⁺) basal ductal and/or MIST1⁺ acinar cells, as well as induction of fibrosis, following irradiation in EGF-treated mice. An additional in vitro experiment using a salivary gland organoid irradiation model indicated that the radioprotective effects of EGF promoted the growth and inhibited the apoptotic cell death of salivary epithelial cells. Our results suggest that retroductal delivery of EGF may be a promising therapeutic option for preventing radiation-induced salivary gland hypofunction.

Rational Design of Nanomaterials for Various Radiation-Induced Diseases Prevention and Treatment

Radiation treatments often unfavorably damage neighboring healthy organs and cause a series of radiation sequelae, such as radiation-induced hematopoietic system diseases, radiation-induced gastrointestinal diseases, radiation-induced lung diseases, and radiation-induced skin diseases. Recently, emerging nanomaterials have exhibited good superiority for these radiation-induced disease treatments. Given this background, the rational design principle of nanomaterials, which helps to optimize the therapeutic efficiency, has been an increasing need. Consequently, it is of great significance to perform a systematic summarization of the advances in this field, which can trigger the development of new high-performance nanoradioprotectors with drug efficiency maximization. Herein, this review highlights the advances and perspectives in the rational design of nanomaterials for preventing and treating various common radiation-induced diseases. Furthermore, the sources, clinical symptoms, and pathogenesis/injury mechanisms of these radiation-induced diseases will also be introduced. Furthermore, current challenges and directions for future efforts in this field are also discussed.

Radiation-Induced Salivary Gland Dysfunction: Mechanisms, Therapeutics and Future Directions

Salivary glands sustain collateral damage following radiotherapy (RT) to treat cancers of the head and neck, leading to complications, including mucositis, xerostomia and hyposalivation. Despite salivary gland-sparing techniques and modified dosing strategies, long-term hypofunction remains a significant problem. Current therapeutic interventions provide temporary symptom relief, but do not address irreversible glandular damage. In this review, we summarize the current understanding of mechanisms involved in RT-induced hyposalivation and provide a framework for future mechanistic studies. One glaring gap in published studies investigating RT-induced mechanisms of salivary gland dysfunction concerns the effect of irradiation on adjacent non-irradiated tissue via paracrine, autocrine and direct cell-cell interactions, coined the bystander effect in other models of RT-induced damage. We hypothesize that purinergic receptor signaling involving P2 nucleotide receptors may play a key role in mediating the bystander effect. We also discuss promising new therapeutic approaches to prevent salivary gland damage due to RT.

Effects of nanoparticle-mediated growth factor gene transfer to the injured microenvironment on the tendon-to-bone healing strength

The tendon-to-bone healing after trauma is usually slow and weak, and the repair site is easily disrupted during early mobilization exercise. bFGF and VEGFA gene therapy may hold promise in augmenting the tendon-to-bone healing process through enhancing cell proliferation and angiogenesis. This study is conducted to determine the effects of nanoparticle-mediated co-delivery of bFGF and VEGFA genes to the tendon-to-bone repair interface on the healing strength and biological responses in a chicken model. The PLGA nanoparticle/pEGFP-bFGF + pEGFP-VEGFA plasmid complexes were prepared and were characterized in vitro and in vivo. The nanoparticle/plasmid complexes can effectively transfer bFGF and VEGFA genes to the tendon-to-bone interface. Nanoparticle-mediated co-delivery of bFGF and VEGFA genes significantly improved the tendon-to-bone healing in terms of healing strengths and histology in a chicken flexor tendon repair model. Our results suggest a new biological approach to accelerate the tendon-to-bone healing.

Building a Functional Salivary Gland for Cell-Based Therapy: More than Secretory Epithelial Acini

A few treatment options exist for patients experiencing xerostomia due to hyposalivation that occurs as a result of disease or injury to the gland. An opportunity for a permanent solution lies in the field of salivary gland replacement through tissue engineering. Recent success emboldens in the vision of producing a tissue-engineered salivary gland composed of differentiated salivary epithelial cells that are able to differentiate to form functional units that produce and deliver saliva to the oral cavity. This vision is augmented by advances in understanding cellular mechanisms that guide branching morphogenesis and salivary epithelial cell polarization in both acinar and ductal structures. Growth factors and other guidance cues introduced into engineered constructs help to develop a more complex glandular structure that seeks to mimic native salivary gland tissue. This review describes the separate epithelial phenotypes that make up the gland, and it describes their relationship with the other cell types such as nerve and vasculature that surround them. The review is organized around the links between the native components that form and contribute to various aspects of salivary gland development, structure, and function and how this information can drive the design of functional tissue-engineered constructs. In addition, we discuss the attributes of various biomaterials commonly used to drive function and form in engineered constructs. The review also contains a current description of the state-of-the-art of the field, including successes and challenges in creating materials for preclinical testing in animal models. The ability to integrate biomolecular cues in combination with a range of materials opens the door to the design of increasingly complex salivary gland structures that, once accomplished, can lead to breakthroughs in other fields of tissue engineering of epithelial-based exocrine glands or oral tissues.

Functional proteomic analysis reveals roles for PKCδ in regulation of cell survival and cell death: Implications for cancer pathogenesis and therapy

Protein Kinase C-δ (PKCδ), regulates a broad group of biological functions and disease processes, including well-defined roles in immune function, cell survival and apoptosis. PKCδ primarily regulates apoptosis in normal tissues and non-transformed cells, and genetic disruption of the PRKCD gene in mice is protective in many diseases and tissue damage models. However pro-survival/pro-proliferative functions have also been described in some transformed cells and in mouse models of cancer. Recent evidence suggests that the contribution of PKCδ to specific cancers may depend in part on the oncogenic context of the tumor, consistent with its paradoxical role in cell survival and cell death. Here we will discuss what is currently known about biological functions of PKCδ and potential paradigms for PKCδ function in cancer. To further understand mechanisms of regulation by PKCδ, and to gain insight into the plasticity of PKCδ signaling, we have used functional proteomics to identify pathways that are dependent on PKCδ. Understanding how these distinct functions of PKCδ are regulated will be critical for the logical design of therapeutics to target this pathway.

Salivary Gland Hypofunction and Xerostomia in Head and Neck Radiation Patients

BACKGROUND

The most manifest long-term consequences of radiation therapy in the head and neck cancer patient are salivary gland hypofunction and a sensation of oral dryness (xerostomia).

METHODS

This critical review addresses the consequences of radiation injury to salivary gland tissue, the clinical management of salivary gland hypofunction and xerostomia, and current and potential strategies to prevent or reduce radiation injury to salivary gland tissue or restore the function of radiation-injured salivary gland tissue.

RESULTS

Salivary gland hypofunction and xerostomia have severe implications for oral functioning, maintenance of oral and general health, and quality of life. Significant progress has been made to spare salivary gland function chiefly due to advances in radiation techniques. Other strategies have also been developed, e.g., radioprotectors, identification and preservation/expansion of salivary stem cells by stimulation with cholinergic muscarinic agonists, and application of new lubricating or stimulatory agents, surgical transfer of submandibular glands, and acupuncture.

CONCLUSION

Many advances to manage salivary gland hypofunction and xerostomia induced by radiation therapy still only offer partial protection since they are often of short duration, lack the protective effects of saliva, or potentially have significant adverse effects. Intensity-modulated radiation therapy (IMRT), and its next step, proton therapy, have the greatest potential as a management strategy for permanently preserving salivary gland function in head and neck cancer patients.Presently, gene transfer to supplement fluid formation and stem cell transfer to increase the regenerative potential in radiation-damaged salivary glands are promising approaches for regaining function and/or regeneration of radiation-damaged salivary gland tissue.

Mouth-Watering Results: Clinical Need, Current Approaches, and Future Directions for Salivary Gland Regeneration

Permanent damage to the salivary glands and resulting hyposalivation and xerostomia have a substantial impact on patient health, quality of life, and healthcare costs. Currently, patients rely on lifelong treatments that alleviate the symptoms, but no long-term restorative solutions exist. Recent advances in adult stem cell enrichment and transplantation, bioengineering, and gene transfer have proved successful in rescuing salivary gland function in a number of animal models that reflect human diseases and that result in hyposalivation and xerostomia. By overcoming the limitations of stem cell transplants and better understanding the mechanisms of cellular plasticity in the adult salivary gland, such studies provide encouraging evidence that a regenerative strategy for patients will be available in the near future.

Salivary gland tissue engineering to attain clinical benefits: a special report

The salivary glands produce saliva, which helps in mediating the oral colonization of microbes, the repair of mucosa, the remineralization of teeth, lubrication and gustation. However, certain medications, therapeutic radiation and certain autoimmune diseases can cause a reduction in the salivary flow. The aim of this report was to review and highlight the indications and techniques of salivary gland engineering to counter hyposalivation. This report concludes that in the literature, numerous strategies have been suggested and discussed pertaining to the engineering of salivary gland, however, challenges remain in terms of its production and accurate function. Dedicated efforts are required from researchers all over the world to obtain the maximum benefits from salivary gland engineering techniques.

Rigor and reproducibility in polymer nanoparticle synthesis and characterization

Standardized process improvement methods and tools were used to enhance the rigor and reproducibility of diblock copolymer nanoparticle (NP) synthesis and characterization. Models linking design parameters with NP characteristics boosted process control for NP synthesis, which may improve translation and commercialization of NP research.

Nanotherapeutics for the Treatment of Cancer and Arthritis

BACKGROUND

Nanotechnology is gaining significant attention worldwide for the treatment of complex diseases such as AIDS (acquired immune deficiency syndrome), cancer and rheumatoid arthritis. Nanomedicine is the application of nanotechnology used for diagnosis and treatment for the disease that includes the preservation and improvement of human health by covering an area such as drug delivery using nanocarriers, nanotheranostics and nanovaccinology. The present article provides an insight into several aspects of nanomedicine such as usages of multiple types of nanocarriers, their status, advantages and disadvantages with reference to cancer and rheumatoid arthritis.

METHODS

An extensive search was performed on the bibliographic database for research article on nanotechnology and nanomedicine along with looking deeply into the aspects of these diseases, and how all of them are co-related. We further combined all the necessary information from various published articles and briefed to provide the current status.

RESULTS

Nanomedicine confers a unique technology against complex diseases which includes early diagnosis, prevention, and personalized therapy. The most common nanocarriers used globally are liposomes, polymeric nanoparticles, dendrimers, metallic nanoparticles, magnetic nanoparticles, solid lipid nanoparticles, polymeric micelles and nanotubes among others.

CONCLUSION

Nanocarriers are used to deliver drugs and biomolecules like proteins, antibody fragments, DNA fragments, and RNA fragments as the base of cancer biomarkers.

ShRNA-mediated matrix metalloproteinase-2 gene silencing protects normal cells and sensitizes cancer cells against ionizing-radiation induced damage

INTRODUCTION

Ionizing radiation (IR) affects healthy tissues during the treatment of cancer radiation therapy and other nuclear and radiological accidents. Some natural compounds showed nonspecific radioprotective activity with severe side effects. The present study is aimed to develop potent and specific radioprotective short hairpin RNA (shRNA), which selectively protects normal cells from IR by specifically targeting matrix metalloproteinases (MMP-2).

RESULTS

IR reduced the viability of human normal dermal fibroblasts (HDFs) in a dose-response manner. It enhanced the expression of MMP-2 at 10 Gy. Plasmid MMP-2shRNA (pMMP-2) reduced the IR (10 Gy) induced cytotoxicity analyzed by lactate dehydrogenase (LDH) assay, normalized IR induced cellular and morphological changes with enhanced the clonogenicity in 48 hours at 2 µg/mL. It reduced the ROS generation, released HDFs from G₂ /M arrest and rescued from apoptosis analyzed by DCFDA dye, cell cycle analysis by PI stain and annexin V assay, respectively. pMMP-2 also modulates the expression of EGFR and reduced IR induced expression of DNA damage response protein, ATM and increased the expression of repair proteins, KU70/KU80, and RAD51. In addition, decreased the expression of cell cycle regulatory proteins cyclin-dependent kinases (CDK1) and Cyclin B as well as proapoptotic proteins BAX, caspase-3, and Cytochrome-C and increased the expression of survival protein, Bcl-2. In contrary pMMP-2 decreased the LDH activity, survival fraction and blocked G₂ /M phase of cell cycle and increased apoptosis in MCF-7 cells. In addition, decreased the expression of EGFR, proapoptotic BAX and DNA repair proteins ATM, KU70/80 and RAD51, increased expression of cyclinB as well as CDK1.

CONCLUSION

Results conclude that pMMP-2 protected HDFs from IR and sensitized the MCF-7 cells. Therefore, pMMP-2 can be employed for better treatment of radiation accidents and during the treatment of radiotherapy.

Salivary Gland Stem Cells and Tissue Regeneration: An Update on Possible Therapeutic Application

The aim of this review is to combine literature and experimental data concerning the impact of salivary gland (SG) stem cells (SCs) and their therapeutic prospects in tissue regeneration. So far, SCs were isolated from human and rodent major and minor SGs that enabled their regeneration. Several scaffolds were also combined with "SCs" and different "proteins" to achieve guided differentiation, although none have been proven as ideal. A new aspect of SC therapy aims to establish a vice versa relationship between SG and other ecto- or endodermal organs such as the pancreas, liver, kidneys, and thyroid. SC therapy could be a cheap and simple, non-traumatic, and individualized therapy for medically challenging cases like xerostomia and major organ failures. Functional improvement has been achieved in these organs, but till date, the whole organ in vivo regeneration was not achieved. Concerns about malignant formations and possible failures are yet to be resolved. In this review article, we highlight the basic embryology of SGs, existence of SG SCs with a detailed exploration of various cellular markers, scaffolds for tissue engineering, and, in the later part, cover potential therapeutic applications with a special focus on the pancreas and liver. Keywords: Salivary gland stem cells, Stem cell therapy, Tissue regeneration.

Effect of MMP-2 gene silencing on radiation-induced DNA damage in human normal dermal fibroblasts and breast cancer cells

Introduction

Diagnostic and therapeutic ionizing radiation (IR) is one of the well known long term risk factors of breast cancer. Extremely lethal consequences of IR causes double-strand breaks, which are mainly responsible for genomic instability, altered gene expression, and cell death.

Findings

This study evaluated the effect of matrix metalloproteinases-2 (MMP-2) gene silencing using MMP-2 shRNA expression plasmids (pMMP-2) on IR induced cytotoxicity and DNA damage by MTT, dead green, γH2AX and comet assays in human normal dermal fibroblasts (HDFs) and MCF-7 human breast cancer cells. IR has decreased the viability of HDFs and MCF-7 cells with increasing IR (2-10Gy). IR induced DNA damage in both HDFs and MCF-7 cells. However, pMMP-2 transfection has increased the viability of irradiated HDFs (10Gy) and significantly decreased the viability of irradiated MCF-7 cells (10Gy). Further, DNA damage in terms of γH2AX foci decreased with pMMP-2 transfection in irradiated HDFs (10Gy) and increased in irradiated MCF-7 cells (10Gy). In addition, MMP-2 gene silencing using pMMP-2 decreased comet tail length in irradiated HDFs but increased in irradiated MCF-7 cells.

Conclusions

The results conclude that pMMP-2 has protected HDFs and sensitized the MCF-7 cells from IR induced DNA damage. This differential response might be due to IR induced MMP-2 distinctive ROS generation in HDFs and MCF-7 cells.

Electronic supplementary material

The online version of this article (10.1186/s41021-019-0131-x) contains supplementary material, which is available to authorized users.

Microparticle Depots for Controlled and Sustained Release of Endosomolytic Nanoparticles

Introduction

Nucleic acids have gained recognition as promising immunomodulatory therapeutics. However, their potential is limited by several drug delivery barriers, and there is a need for technologies that enhance intracellular delivery of nucleic acid drugs. Furthermore, controlled and sustained release is a significant concern, as the kinetics and localization of immunomodulators can influence resultant immune responses. Here, we describe the design and initial evaluation of poly(lactic-co-glycolic) acid (PLGA) microparticle (MP) depots for enhanced retention and sustained release of endosomolytic nanoparticles that enable the cytosolic delivery of nucleic acids.

Methods

Endosomolytic p[DMAEMA]_10kD-bl-[PAA_0.3-co-DMAEMA_0.3-co-BMA_0.4]_25kD diblock copolymers were synthesized by reversible addition-fragmentation chain transfer polymerization. Polymers were electrostatically complexed with nucleic acids and resultant nanoparticles (NPs) were encapsulated in PLGA MPs. To modulate release kinetics, ammonium bicarbonate was added as a porogen. Release profiles were quantified in vitro and in vivo via quantification of fluorescently-labeled nucleic acid. Bioactivity of released NPs was assessed using small interfering RNA (siRNA) targeting luciferase as a representative nucleic acid cargo. MPs were incubated with luciferase-expressing 4T1 (4T1-LUC) breast cancer cells in vitro or administered intratumorally to 4T1-LUC breast tumors, and silencing via RNA interference was quantified via longitudinal luminescence imaging.

Results

Endosomolytic NPs complexed to siRNA were effectively loaded into PLGA MPs and release kinetics could be modulated in vitro and in vivo via control of MP porosity, with porous MPs exhibiting faster cargo release. In vitro, release of NPs from porous MP depots enabled sustained luciferase knockdown in 4T1 breast cancer cells over a five-day treatment period. Administered intratumorally, MPs prolonged the retention of nucleic acid within the injected tumor, resulting in enhanced and sustained silencing of luciferase relative to a single bolus administration of NPs at an equivalent dose.

Conclusion

This work highlights the potential of PLGA MP depots as a platform for local release of endosomolytic polymer NPs that enhance the cytosolic delivery of nucleic acid therapeutics.

EGF receptor and PKCδ kinase activate DNA damage-induced pro-survival and pro-apoptotic signaling via biphasic activation of ERK and MSK1 kinases

DNA damage-mediated activation of extracellular signal-regulated kinase (ERK) can regulate both cell survival and cell death. We show here that ERK activation in this context is biphasic and that early and late activation events are mediated by distinct upstream signals that drive cell survival and apoptosis, respectively. We identified the nuclear kinase mitogen-sensitive kinase 1 (MSK1) as a downstream target of both early and late ERK activation. We also observed that activation of ERK→MSK1 up to 4 h after DNA damage depends on epidermal growth factor receptor (EGFR), as EGFR or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)/ERK inhibitors or short hairpin RNA-mediated MSK1 depletion enhanced cell death. This prosurvival response was partially mediated through enhanced DNA repair, as EGFR or MEK/ERK inhibitors delayed DNA damage resolution. In contrast, the second phase of ERK→MSK1 activation drove apoptosis and required protein kinase Cδ (PKCδ) but not EGFR. Genetic disruption of PKCδ reduced ERK activation in an in vivo irradiation model, as did short hairpin RNA-mediated depletion of PKCδ in vitro In both models, PKCδ inhibition preferentially suppressed late activation of ERK. We have shown previously that nuclear localization of PKCδ is necessary and sufficient for apoptosis. Here we identified a nuclear PKCδ→ERK→MSK1 signaling module that regulates apoptosis. We also show that expression of nuclear PKCδ activates ERK and MSK1, that ERK activation is required for MSK1 activation, and that both ERK and MSK1 activation are required for apoptosis. Our findings suggest that location-specific activation by distinct upstream regulators may enable distinct functional outputs from common signaling pathways.

Application of Multifunctional Nanomaterials in Radioprotection of Healthy Tissues

Radiotherapy has been extensively used in clinic for malignant tumors treatment. However, a severe challenge of it is that the ionizing radiation needed to kill tumors inevitably causes damage to surrounding normal tissues. Although some of the molecular radioprotective drugs, such as amifostine, have been used as clinical adjuvants to radio-protect healthy tissues, their shortcomings such as short systemic circulation time and fast biological clearing from the body largely hinder the sustained bioactivity. Recently, with the rapid development of nanotechnology in the biological field, the multifunctional nanomaterials not only establish powerful drug delivery systems to improve the molecular radioprotective drugs' biological availability, but also open a new route to develop neozoic radioprotective agents because some nanoparticles possess intrinsic radioprotective abilities. Therefore, considering these overwhelming superiorities, this review systematically summarizes the advances in healthy tissue radioprotection applications of multifunctional nanomaterials. Furthermore, this review also points out a perspective of nanomaterial designs for radioprotection applications and discusses the challenges and future outlooks of the nanomaterial-mediated radioprotection.

Localized Delivery of Amifostine Enhances Salivary Gland Radioprotection

Radiotherapy for head and neck cancers commonly causes damage to salivary gland tissue, resulting in xerostomia (dry mouth) and numerous adverse medical and quality-of-life issues. Amifostine is the only Food and Drug Administration-approved radioprotective drug used clinically to prevent xerostomia. However, systemic administration of amifostine is limited by severe side effects, including rapid decrease in blood pressure (hypotension), nausea, and a narrow therapeutic window. In this study, we demonstrate that retroductal delivery of amifostine and its active metabolite, WR-1065, to murine submandibular glands prior to a single radiation dose of 15 Gy maintained gland function and significantly increased acinar cell survival. Furthermore, in vivo stimulated saliva secretion was maintained in retrograde-treated groups at levels significantly higher than irradiated-only and systemically treated groups. In contrast to intravenous injections, retroductal delivery of WR-1065 or amifostine significantly attenuated hypotension. We conclude that localized delivery to salivary glands markedly improves radioprotection at the cellular level, as well as mitigates the adverse side effects associated with systemic administration. These results support the further development of a localized delivery system that would be compatible with the fractionated dose regimen used clinically.

Radioactive iodine: An unappreciated threat to salivary gland function

Thyroid cancer is an endocrine malignancy whose prevalence is increasing in the United States. Nearly 57,000 new cases of thyroid cancer are estimated to be diagnosed in 2017. The standard of care for differentiated thyroid cancer is thyroidectomy followed by ablation of thyroid remnants with high-dose radioactive iodine (¹³¹ I). Apart from thyroid glands, ¹³¹ I accumulates in cells of salivary glands and compromises its function. Xerostomia is, therefore, a frequent and often persistent complaint of patients. Despite adoption of standard preventive measures, parenchymal damage and chronic salivary dysfunction are observed in a substantial number of patients. Saliva is important for oral homeostasis, and its reduction increases the risk of oral morbidity. As differentiated thyroid cancer patients have an excellent survival rate, preservation of salivary gland function carries added significance. A focus on treatments that preserve or restore long-term salivary flow can significantly improve the quality of life of thyroid cancer survivors.

Degradable poly(ethylene glycol) (PEG)-based hydrogels for spatiotemporal control of siRNA/nanoparticle delivery

Despite great therapeutic potential and development of a repertoire of delivery approaches addressing degradation and cellular uptake limitations, small interfering RNA (siRNA) exhibits poorly controlled tissue-specific localization. To overcome this hurdle, siRNA was complexed to nanoparticles (siRNA/NP) embedded within poly(ethylene glycol)-poly(lactic acid)-dimethacrylate (PEG-PLA-DM) hydrogels with the hypothesis that hydrolytic degradation of ester bonds within the PLA crosslinks would provide tunable, sustained siRNA/NP release. Hydrogels formed from macromers with increasing PLA repeats (e.g., 0 or non-degradable to 5 PLA repeats flanking PEG cores) and mixtures of nondegradable PEG-DM (0 PLA) and degradable PEG-PLA₅-DM macromers were investigated. Hydrogels formed only with fully degradable crosslinks degraded rapidly over 6-14 days with limited control over siRNA/NP release. However, hydrogels formed with mixtures of nondegradable and 20%, 50%, and 100% degradable macromers resulted in siRNA/NP release over 3 to 28 days. Subsequently, gene silencing mediated by released siRNA/NP from 20% and 50% degradable hydrogels was sustained for ~28 days. Furthermore, in vivo imaging showed that hydrogel degradation controlled siRNA/NP localization, with sustained siRNA/NP release from 0%, 20% and 50% degradable hydrogels over 28, 21, and 15 days. A model, which accounts for hydrogel degradation rate and siRNA/NP diffusion, was developed to enable rational design of siRNA/NP delivery depots. Overall, this study shows that siRNA/NP release can be sustained via encapsulation in hydrogels with tunable degradation kinetics and modeled for a priori design of delivery depots.

Murine Salivary Functional Assessment via Pilocarpine Stimulation Following Fractionated Radiation

Hyposalivation is commonly observed in the autoimmune reaction of Sjögren's syndrome or following radiation injury to the major salivary glands. In these cases, questions remain regarding disease pathogenesis and effective interventions. An optimized technique that allows functional assessment of the salivary glands is invaluable for investigating exocrine gland biology, dysfunction, and therapeutics. Here, we present a step by step approach to performing pilocarpine stimulated saliva secretion, including tracheostomy and the dissection of the three major murine salivary glands. We also detail the appropriate murine head and neck anatomy accessed during these techniques. This approach is scalable, allowing for multiple mice to be processed simultaneously, thus improving the efficiency of the work flow. We aim to improve the reproducibility of these methods, each of which has further applications within the field. In addition to saliva collection, we discuss metrics for quantifying and normalizing functional capacity of these tissues. Representative data are included from submandibular glands with depressed salivary gland function 2 weeks following fractionated radiation (4 doses of 6.85 Gy).

Retroductal Nanoparticle Injection to the Murine Submandibular Gland

Two common goals of salivary gland therapeutics are prevention and cure of tissue dysfunction following either autoimmune or radiation injury. By locally delivering bioactive compounds to the salivary glands, greater tissue concentrations can be safely achieved versus systemic administration. Furthermore, off target tissue effects from extra-glandular accumulation of material can be dramatically reduced. In this regard, retroductal injection is a widely used method for investigating both salivary gland biology and pathophysiology. Retroductal administration of growth factors, primary cells, adenoviral vectors, and small molecule drugs has been shown to support gland function in the setting of injury. We have previously shown the efficacy of a retroductally injected nanoparticle-siRNA strategy to maintain gland function following irradiation. Here, a highly effective and reproducible method to administer nanomaterials to the murine submandibular gland through Wharton's duct is detailed (Figure 1). We describe accessing the oral cavity and outline the steps necessary to cannulate Wharton's duct, with further observations serving as quality checks throughout the procedure.

Comparing human and mouse salivary glands: A practice guide for salivary researchers

Mice are a widely utilized in vivo model for translational salivary gland research but must be used with caution. Specifically, mouse salivary glands are similar in many ways to human salivary glands (i.e., in terms of their anatomy, histology, and physiology) and are both readily available and relatively easy and affordable to maintain. However, there are some significant differences between the two organisms, and by extension, the salivary glands derived from them must be taken into account for translational studies. The current review details pertinent similarities and differences between human and mouse salivary glands and offers practical guidelines for using both for research purposes.

Serpine1 Knockdown Enhances MMP Activity after Flexor Tendon Injury in Mice: Implications for Adhesions Therapy

Injuries to flexor tendons can be complicated by fibrotic adhesions, which severely impair the function of the hand. Adhesions have been associated with TGF-β1, which causes upregulation of PAI-1, a master suppressor of protease activity, including matrix metalloproteinases (MMP). In the present study, the effects of inhibiting PAI-1 in murine zone II flexor tendon injury were evaluated utilizing knockout (KO) mice and local nanoparticle-mediated siRNA delivery. In the PAI-1 KO murine model, reduced adherence of injured tendon to surrounding subcutaneous tissue and accelerated recovery of normal biomechanical properties compared to wild type controls were observed. Furthermore, MMP activity was significantly increased in the injured tendons of the PAI-1 KO mice, which could explain their reduced adhesions and accelerated remodeling. These data demonstrate that PAI-1 mediates fibrotic adhesions in injured flexor tendons by suppressing MMP activity. In vitro siRNA delivery to silence Serpine1 expression after treatment with TGF-β1 increased MMP activity. Nanoparticle-mediated delivery of siRNA targeting Serpine1 in injured flexor tendons significantly reduced target gene expression and subsequently increased MMP activity. Collectively, the data demonstrate that PAI-1 can be a druggable target for treating adhesions and accelerating the remodeling of flexor tendon injuries.

Development of controlled drug delivery systems for bone fracture-targeted therapeutic delivery: A review

Impaired fracture healing is a major clinical problem that can lead to patient disability, prolonged hospitalization, and significant financial burden. Although the majority of fractures heal using standard clinical practices, approximately 10% suffer from delayed unions or non-unions. A wide range of factors contribute to the risk for nonunions including internal factors, such as patient age, gender, and comorbidities, and external factors, such as the location and extent of injury. Current clinical approaches to treat nonunions include bone grafts and low-intensity pulsed ultrasound (LIPUS), which realizes clinical success only to select patients due to limitations including donor morbidities (grafts) and necessity of fracture reduction (LIPUS), respectively. To date, therapeutic approaches for bone regeneration rely heavily on protein-based growth factors such as INFUSE, an FDA-approved scaffold for delivery of bone morphogenetic protein 2 (BMP-2). Small molecule modulators and RNAi therapeutics are under development to circumvent challenges associated with traditional growth factors. While preclinical studies has shown promise, drug delivery has become a major hurdle stalling clinical translation. Therefore, this review overviews current therapies employed to stimulate fracture healing pre-clinically and clinically, including a focus on drug delivery systems for growth factors, parathyroid hormone (PTH), small molecules, and RNAi therapeutics, as well as recent advances and future promise of fracture-targeted drug delivery.

The Effects of Biological Fluids on Colloidal Stability and siRNA Delivery of a pH-Responsive Micellar Nanoparticle Delivery System

Nanoparticles (NPs) interact with complex protein milieus in biological fluids, and these interactions have profound effects on NP physicochemical properties and function. Surprisingly, most studies neglect the impact of these interactions, especially with respect to NP-mediated siRNA delivery. Here, the effects of serum on colloidal stability and siRNA delivery of a pH-responsive micellar NP delivery system were characterized. Results show cationic NP-siRNA complexes aggregate in ≥2% serum in buffer, but are stable in serum-free media. Furthermore, nonaggregated NP-siRNA delivered in serum-free media result in 4-fold greater siRNA uptake in vitro, compared to aggregated NP-siRNA. Interestingly, pH-responsive membrane lysis behavior, which is required for endosomal escape, and NP-siRNA dissociation, necessary for gene knockdown, are significantly reduced in serum. Consistent with these data, nonaggregated NP-siRNA in serum-free conditions result in highly efficient gene silencing, even at doses as low as 5 nM siRNA. NP-siRNA diameter was measured at albumin and IgG levels mimicking biological fluids. Neither albumin nor IgG alone induces NP-siRNA aggregation, implicating other serum proteins in NP colloidal instability. Finally, as a proof-of-principle that stability is maintained in established in vivo models, transmission electron microscopy reveals NP-siRNA are taken up by ductal epithelial cells in a nonaggregated state when injected retroductally into mouse salivary glands in vivo. Overall, this study shows serum-induced NP-siRNA aggregation significantly diminishes efficiency of siRNA delivery by reducing uptake, pH-responsive membrane lysis activity, and NP-siRNA dissociation. Moreover, these results highlight the importance of local NP-mediated drug delivery and are broadly applicable to other drug delivery systems.