Adenosine promotes wound healing and mediates angiogenesis in response to tissue injury via occupancy of A(2A) receptors

Adenosine A2B receptor agonist improves epidermal barrier integrity in a murine model of epidermal hyperplasia

Adenosine regulates multiple physiological processes through the activation of four receptor subtypes, of which the A2B adenosine receptor (A2BAR) has the lowest affinity for adenosine. Being the adenosine receptor subtype most prominently expressed in epidermis, we recently described the antiproliferative and anti-inflammatory effect of the selective A2BAR agonist BAY60-6583 (BAY) in human keratinocytes stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA), so we sought to establish the effect of topical application of BAY in a model of murine epidermal hyperplasia. Topical application of BAY (1 or 10 μg/site) prevented the inflammatory reaction and skin lesions induced by TPA, minimizing hyperproliferation and acanthosis, as well as the expression of specific markers of proliferative keratinocytes. On the other hand, pre-treatment with the selective A2BAR antagonist, PSB-1115 (PSB, 5 or 50 μg/site) reversed these beneficial effects. Additionally, BAY application normalized the expression of epidermal barrier proteins, whose integrity is altered in inflammatory skin diseases, while treatment with the antagonist alone worsened it. Our results, besides confirming the anti-inflammatory and antiproliferative effects of the A2BAR agonist, further demonstrate a role of A2BAR activation to preserve the epidermal barrier. Therefore, the activation of A2BAR may constitute a possible new pharmacological target for the treatment of skin inflammatory diseases such as psoriasis.

Targeting adenosine A2A receptors for early intervention of retinopathy of prematurity

Retinopathy of prematurity (ROP) continues to pose a significant threat to the vision of numerous children worldwide, primarily owing to the increased survival rates of premature infants. The pathologies of ROP are mainly linked to impaired vascularization as a result of hyperoxia, leading to subsequent neovascularization. Existing treatments, including anti-vascular endothelial growth factor (VEGF) therapies, have thus far been limited to addressing pathological angiogenesis at advanced ROP stages, inevitably leading to adverse side effects. Intervention to promote physiological angiogenesis during the initial stages could hold the potential to prevent ROP. Adenosine A2A receptors (A2AR) have been identified in various ocular cell types, exhibiting distinct densities and functionally intricate connections with oxygen metabolism. In this review, we discuss experimental evidence that strongly underscores the pivotal role of A2AR in ROP. In particular, A2AR blockade may represent an effective treatment strategy, mitigating retinal vascular loss by reversing hyperoxia-mediated cellular proliferation inhibition and curtailing hypoxia-mediated neovascularization in oxygen-induced retinopathy (OIR). These effects stem from the interplay of endothelium, neuronal and glial cells, and novel molecular pathways (notably promoting TGF-β signaling) at the hyperoxia phase. We propose that pharmacological targeting of A2AR signaling may confer an early intervention for ROP with distinct therapeutic benefits and mechanisms than the anti-VEGF therapy.

Fish Skin Grafts Affect Adenosine and Methionine Metabolism during Burn Wound Healing

Burn wound healing is a complex process orchestrated through successive biochemical events that span from weeks to months depending on the depth of the wound. Here, we report an untargeted metabolomics discovery approach to capture metabolic changes during the healing of deep partial-thickness (DPT) and full-thickness (FT) burn wounds in a porcine burn wound model. The metabolic changes during healing could be described with six and seven distinct metabolic trajectories for DPT and FT wounds, respectively. Arginine and histidine metabolism were the most affected metabolic pathways during healing, irrespective of burn depth. Metabolic proxies for oxidative stress were different in the wound types, reaching maximum levels at day 14 in DPT burns but at day 7 in FT burns. We examined how acellular fish skin graft (AFSG) influences the wound metabolome compared to other standard-or-care burn wound treatments. We identified changes in metabolites within the methionine salvage pathway, specifically in DPT burn wounds that is novel to the understanding of the wound healing process. Furthermore, we found that AFSGs boost glutamate and adenosine in wounds that is of relevance given the importance of purinergic signaling in regulating oxidative stress and wound healing. Collectively, these results serve to define biomarkers of burn wound healing. These results conclusively contribute to the understanding of the multifactorial mechanism of the action of AFSG that has traditionally been attributed to its structural properties and omega-3 fatty acid content.

Adenosine A2A Receptor Agonist, Polydeoxyribonucleotide Treatment Improves Locomotor Function and Thermal Hyperalgesia Following Neuropathic Pain in Rats

PURPOSE

Lithotomy position has been widely used in the various urologic surgery. Occasionally sensory and motor problems of the lower extremities are occurred due to the lithotomy position and these deficits may be related with sciatic nerve injury (SNI). Inflammatory process is a factor to induce functional impairment after SNI. Therefore, we evaluated the role of adenosine A2A receptor agonists, polydeoxyribonucleotide (PDRN) showing anti-inflammatory effect on locomotor function following SNI in rats.

METHODS

Sciatic nerve was compressed with surgical clips for 1 minute after exposing of right sciatic nerve. After 3 days of SNI, PDRN (2, 4, and 8 mg/kg) was applied to the damaged area of sciatic nerve once daily for 10 days. Walking track analysis was conducted for locomotor function and plantar test was performed for thermal pain sensitivity. Level of cyclic adenosine-3´,5´-monophosphate (cAMP) were measured using enzyme-linked immunosorbent assay. Western blot analysis was performed for tumor necrosis factor (TNF)-α, interleukin (IL)-1β, cAMP response element binding protein (CREP), vascular endothelial growth factor (VEGF). Immunofluorescence for neurofilament was also conducted.

RESULTS

Locomotor function was decreased and thermal pain sensitivity was increased by SNI. SNI enhanced proinflammatory cytokines' production, such as TNF-α and IL-1β, while suppressed CREP phosphorylation and cAMP level. SNI also reduced the expression of VEGF and neurofilaments. However, treatment with PDRN inhibited proinflammatory cytokines' production and upregulated CREP phosphorylation and cAMP expression. PDRN also enhanced the expression of VEGF and neurofilaments. As a result, PDRN improved locomotor function and alleviated thermal hyperalgesia after SNI.

CONCLUSION

PDRN has shown potential to be used as an effective treatment for neuropathic pain.

Functional Microneedle Patch for Wound Healing and Biological Diagnosis and Treatment

Wound healing, especially chronic wounds, has been one of the major challenges in the field of biomedicine. Drug therapy alone is not effective, so a variety of functional wound healing dressings have been developed. Microneedles have attracted more and more attentions in the field of wound healing dressings due to their penetration and high drug delivery efficiency. In this review, all the studies on the application of microneedles in wound healing in recent years are summarized, classify different microneedles according to their functions in the process of wound healing, discuss the current challenges in the transformation of microneedle technology toward clinical applications, and finally look forward to the future design and development directions of microneedles in this field.

Caffeine in Skincare: Its Role in Skin Cancer, Sun Protection, and Cosmetics

Caffeine is ubiquitous in our society-not only in the drinks consumed but also increasingly in dermatologic topicals. Given that coffee and caffeine are increasingly used for the production of many dermatologic anti-cancer topicals, sunscreens, and cosmetics, it is of imperative importance to review the basic science and clinical evidence for such claims. In this concise review, we outline the current evidence.

Targeting Adenosine Signalling in Knee Chondropathy: The Combined Action of Polydeoxyribonucleotide and Pulsed Electromagnetic Fields: A Current Concept Review

Chondropathy of the knee is one of the most frequent degenerative cartilage pathologies with advancing age. Scientific research has, in recent years, advanced new therapies that target adenosine A2 receptors, which play a significant role in human health against many disease states by activating different protective effects against cell sufferance and damage. Among these, it has been observed that intra-articular injections of polydeoxyribonucleotides (PDRN) and Pulsed Electromagnetic Fields (PEMF) can stimulate the adenosine signal, with significant regenerative and healing effects. This review aims to depict the role and therapeutic modulation of A2A receptors in knee chondropathy. Sixty articles aimed at providing data for our study were included in this review. The present paper highlights how intra-articular injections of PDRN create beneficial effects by reducing pain and improving functional clinical scores, thanks to their anti-inflammatory action and the important healing and regenerating power of the stimulation of cell growth, production of collagen, and the extracellular matrix. PEMF therapy is a valid option in the conservative treatment of different articular pathologies, including early OA, patellofemoral pain syndrome, spontaneous osteonecrosis of the knee (SONK), and in athletes. PEMF could also be used as a supporting therapy after an arthroscopic knee procedure total knee arthroplasty to reduce the post-operative inflammatory state. The proposal of new therapeutic approaches capable of targeting the adenosine signal, such as the intra-articular injection of PDRN and the use of PEMF, has shown excellent beneficial results compared to conventional treatments. These are presented as an extra weapon in the fight against knee chondropathy.

Smart microneedle patches for wound healing and management

The number of patients with non-healing wounds is generally increasing globally, placing a huge social and economic burden on every country. The complexity of the wound-healing process remains a major health challenge despite the numerous studies that have been reported on conventional wound dressings. Therefore, a therapeutic system that combines diagnostic and therapeutic modalities is essential to monitor wound-related biomarkers and facilitate wound healing in real time. Microneedles, as a multifunctional platform, are promising for transdermal diagnostics and drug delivery. Their advantages are mainly reflected in painless transdermal drug delivery, good biocompatibility, and ease of self-administration. In this work, we review recent advances in the use of microneedle patches for wound healing and monitoring. The paper first provides a brief overview of the skin structure and the wound healing process, and then discusses the current state of research and prospects for the development of wound-related biomarkers and their real-time monitoring based on microneedle sensors. It summarizes the current state of research based on the unique design of microneedle patches, including biomimetic, conductive, and environmentally responsive, to achieve wound healing. It further summarizes the prospects for the application of different microneedle-based drug delivery modalities and drug delivery substances for wound healing, due to their superior transdermal drug delivery advantages. It concludes with challenges and expectations for the use of smart microneedle patches for wound healing and management.

Polydeoxyribonucleotide in the Treatment of Tendon Disorders, from Basic Science to Clinical Practice: A Systematic Review

Polydeoxyribonucleotide (PDRN) is a proprietary and registered drug with several beneficial effects, including tissue repairing, anti-ischemic action, and anti-inflammatory properties. The present study aims to summarize the current evidence about PRDN's clinical effectiveness in the management of tendon disorders. From January 2015 to November 2022, OVID-MEDLINE^®, EMBASE, Cochrane Library, SCOPUS, Web of Science, Google Scholar and PubMed were searched to identify relevant studies. The methodological quality of the studies was evaluated, and relevant data were extracted. Nine studies (two in vivo studies and seven clinical studies) were finally included in this systematic review. Overall, 169 patients (male: 103) were included in the present study. The effectiveness and safeness of PDRN has been investigated in the management of the following diseases: plantar fasciitis; epicondylitis; Achilles tendinopathy; pes anserine bursitis; chronic rotator cuff disease. No adverse effects have been recorded in the included studies and all the patients showed an improvement in clinical symptoms during the follow-up. PDRN are a valid emerging therapeutic drug in the treatment of tendinopathies. Further multicentric randomized clinical studies are needed to better define the therapeutic role of PDRN, especially in combined clinical protocols.

Combinatorial delivery of CPI444 and vatalanib loaded on PEGylated graphene oxide as an effective nanoformulation to target glioblastoma multiforme: In vitro evaluation

Glioblastoma multiforme (GBM) is known as the primary malignant and most devastating form of tumor found in the central nervous system of the adult population. The active pharmaceutical component in current chemotherapy regimens is mostly hydrophobic and poorly water-soluble, which hampers clinical implications. Nanodrug formulations using nanocarriers loaded with such drugs assisted in water dispersibility, improved cellular permeability, and drug efficacy at a low dose, thus adding to the overall practical value. Here, we successfully developed a water-dispersible and biocompatible nanocargo (GO-PEG) based on covalently modified graphene oxide (GO) with a 6-armed poly(ethylene glycol) amine dendrimer for effective loading of the two hydrophobic anticancer drug molecules, CPI444 and vatalanib. These drug molecules target adenosine receptor (A2AR), vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and type III stem cell receptor tyrosine kinase (c-KIT), which plays a crucial role in cancers. The effective cellular delivery of the drugs when loaded on GO-PEG is attributed to the increased permeability of the drug-nanoconjugate formulation. We observed that this combinatorial drug treatment with nanocargo resulted in a significant reduction in the overall cell survival as supported by reduced calcium levels and stem cell markers such as Oct4 and Nanog, which are two of the prime factors for GBM stem cell proliferation. Furthermore, reduced expression of CD24 upon treatment with nanoformulation impeded cellular migration. Cellular assays confirmed inhibition of cell proliferation, migration, and angiogenic potential of GBM treated with GO-PEG–Drug conjugates. Ultimately, GBM U87 cells assumed programmed cell death at a very low concentration due to nanocarrier-mediated drug delivery along with the chosen combination of drugs. Together, this study demonstrated the advantage of GO-PEG mediated combined delivery of CPI444 and vatalanib drugs with increased permeability, a three-pronged combinatorial strategy toward effective GBM treatment.

The Effects of CD73 on Gastrointestinal Cancer Progression and Treatment

Gastrointestinal (GI) cancer is a common and deadly malignant tumor. CD73, a cell-surface protein, acts as a switch of the adenosine-related signaling pathway that can cause significant immunosuppression. Recent evidence has emerged that CD73 is a promising immunotherapy target for regaining immune cell function and restraining tumorigenesis, and a growing stream of research indicates that combining immunotherapy with other therapies can effectively improve the prognosis and survival of GI cancer patients. Several immune checkpoint inhibitors have been approved for use in GI cancer recently; however, they have demonstrated limited efficacy. Solving the problem of immunosuppression in GI cancer is the key to developing an effective therapeutic option and the modulation of CD73 expression may provide an answer. In this review, we discuss current research on CD73 in gastric, liver, pancreatic, and colorectal cancer to evaluate its therapeutic potential as an immunotherapy target in GI cancers.

The Role of Adenosine Receptor A2A in the Regulation of Macrophage Exosomes and Vascular Endothelial Cells During Bone Healing

Background

Macrophage exosomes and vascular endothelial cells (VECs) are critical to bone healing. However, few studies explore the molecular regulation of them in the bone fracture microenvironment.

Methods

In this study, we explored the effects of adenosine receptor A2A (ADA2AR) in macrophage exosomes and VECs during bone healing. CGS21680 (an ADA2AR agonist) and ZM241385 (an ADA2AR antagonist) were used. First, the effects of the ADA2AR on VECs during bone healing were studied in vivo in a rat tibial fracture model. Second, the effects of ADA2AR on VECs and in the regulation of VECs by macrophages were examined in the bone fracture microenvironment. Third, the effects of ADA2AR on the regulation of macrophage exosomes on VECs were analyzed. Finally, the genes and long non-coding RNAs (lncRNAs) associated with the regulation of VECs by the ADA2AR were examined by high-throughput sequencing and bioinformatics analysis.

Results

CGS21680 accelerated VEC proliferation in the early stage of bone healing and that ZM241385 suppressed VEC proliferation in vivo. ZM241385 inhibited cell viability and tube formation in vitro. However, CGS21680 did not promote tube formation, cell proliferation, or cell migration in vitro. The inhibition of macrophage exosomes could suppress tube formation and VEC migration. CGS21680 had no effects on tube formation in a macrophage-VEC co-culture. The macrophage exosomes were purified and CGS21680 promoted the macrophage secretion of exosomes. In contrast, ZM241385 inhibited the macrophage secretion exosomes. Finally, the lncRNA and mRNA involved in the activation of the ADA2AR in VECs were analyzed. CGS21680 upregulated 3274 mRNAs and downregulated 2236 mRNAs, and upregulated 1696 lncRNAs and downregulated 1882 lncRNAs. The hub genes involved in angiogenesis were Flt1, Fgf2, Mapk14, Fn1, and Jun.

Conclusion

The activation of ADA2AR was essential for angiogenesis and the secretion of exosomes by macrophages during bone healing; moreover, the inactivation of the ADA2AR led to poor angiogenesis and bone nonunion.

MXene-Integrated Microneedle Patches with Innate Molecule Encapsulation for Wound Healing

Wound healing is a complex physiological process that involves coordinated phases such as inflammation and neovascularization. Attempts to promote the healing process tend to construct an effective delivery system based on different drugs and materials. In this paper, we propose novel MXene-integrated microneedle patches with adenosine encapsulation for wound healing. Owing to the dynamic covalent bonding capacity of boronate molecules with adenosine, 3-(acrylamido)phenylboronic acid- (PBA-) integrated polyethylene glycol diacrylate (PEGDA) hydrogel is utilized as the host material of microneedle patches. Benefitting from photothermal conversion capacity of MXene, the release of loaded adenosine could be accelerated under NIR irradiation for maintaining the activation signal around injury site. In vitro cell experiments proved the effect of MXene-integrated microneedle patches with adenosine encapsulation in enhancing angiogenesis. When applied for treating animal models, it is demonstrated that the microneedle patches efficiently promote angiogenesis, which is conductive to wound healing. These features make the proposed microneedle patch potential for finding applications in wound healing and other biomedical fields.

Adenosine and Cordycepin Accelerate Tissue Remodeling Process through Adenosine Receptor Mediated Wnt/β-Catenin Pathway Stimulation by Regulating GSK3b Activity

Adenosine is a cellular metabolite with diverse derivatives that possesses a wide range of physiological roles. We investigated the molecular mechanisms of adenosine and cordycepin for their promoting effects in wound-healing process. The mitochondrial energy metabolism and cell proliferation markers, cAMP responsive element binding protein 1 (CREB1) and Ki67, were enhanced by adenosine and cordycepin in cultured dermal fibroblasts. Adenosine and cordycepin stimulated adenosine receptor signaling via elevated cAMP. The phosphorylation of mitogen-activated protein kinase kinase (MEK) 1/2, mammalian target of rapamycin (mTOR) and glycogen synthase kinase 3 beta (Gsk3b) and Wnt target genes such as bone morphogenetic protein (BMP) 2/4 and lymphoid enhancer binding factor (Lef) 1 were activated. The enhanced gene expression by adenosine and cordycepin was abrogated by adenosine A_2A and A_2B receptor inhibitors, ZM241385 and PSH603, and protein kinase A (PKA) inhibitor H89, indicating the involvement of adenosine receptor A_2A, A_2B and PKA. As a result of Wnt/β-catenin pathway activation, the secretion of growth factors such as insulin-like growth factor (IGF)-1 and transforming growth factor beta (TGFβ) 3 was increased, previously reported to facilitate the wound healing process. In addition, in vitro fibroblast migration was also increased, demonstrating their possible roles in facilitating the wound healing process. In conclusion, our data strongly demonstrate that adenosine and cordycepin stimulate the Wnt/β-catenin signaling through the activation of adenosine receptor, possibly promoting the tissue remodeling process and suggest their therapeutic potential for treating skin wounds.

Integrated Bioactive Scaffold with Polydeoxyribonucleotide and Stem-Cell-Derived Extracellular Vesicles for Kidney Regeneration

Kidney tissue engineering and regeneration approaches offer great potential for chronic kidney disease treatment, but kidney tissue complexity imposes an additional challenge in applying regenerative medicine for renal tissue regeneration. In this study, a porous pneumatic microextrusion (PME) composite scaffold consisting of poly(lactic-co-glycolic acid) (PLGA, P), magnesium hydroxide (MH, M), and decellularized porcine kidney extracellular matrix (kECM, E) is functionalized with bioactive compounds, polydeoxyribonucleotide (PDRN), and tumour necrosis factor-α (TNF-α)/interferon-γ (IFN-γ)-primed mesenchymal stem-cell-derived extracellular vesicles (TI-EVs) to improve the regeneration and maintenance of a functional kidney tissue. The combination of PDRN and TI-EVs showed a significant synergistic effect in regenerative processes including cellular proliferation, angiogenesis, fibrosis, and inflammation. In addition, the PME/PDRN/TI-EV scaffold induced an effective glomerular regeneration and restoration of kidney function compared to the existing PME scaffold in a partial nephrectomy mouse model. Therefore, such an integrated bioactive scaffold that combines biochemical cues from PDRN and TI-EVs and biophysical cues from a porous PLGA scaffold containing MH and kECM can be used as an advanced tissue engineering platform for kidney tissue regeneration.

Annexin A2-Mediated Plasminogen Activation in Endothelial Cells Contributes to the Proangiogenic Effect of Adenosine A2A Receptors

Adenosine A_2A receptor mediates the promotion of wound healing and revascularization of injured tissue, in healthy and animals with impaired wound healing, through a mechanism depending upon tissue plasminogen activator (tPA), a component of the fibrinolytic system. In order to evaluate the contribution of plasmin generation in the proangiogenic effect of adenosine A_2A receptor activation, we determined the expression and secretion of t-PA, urokinase plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1) and annexin A2 by human dermal microvascular endothelial cells stimulated by the selective agonist CGS-21680. The plasmin generation was assayed through an enzymatic assay and the proangiogenic effect was studied using an endothelial tube formation assay in Matrigel. Adenosine A_2A receptor activation in endothelial cells diminished the release of PAI-1 and promoted the production of annexin A2, which acts as a cell membrane co-receptor for plasminogen and its activator tPA. Annexin A2 mediated the increased cell membrane-associated plasmin generation in adenosine A_2A receptor agonist treated human dermal microvascular endothelial cells and is required for tube formation in an in vitro model of angiogenesis. These results suggest a novel mechanism by which adenosine A_2A receptor activation promotes angiogenesis: increased endothelial expression of annexin A2, which, in turn, promotes fibrinolysis by binding tPA and plasminogen to the cell surface.

Adenosine Diphosphate Improves Wound Healing in Diabetic Mice Through P2Y12 Receptor Activation

Chronic wounds are a public health problem worldwide, especially those related to diabetes. Besides being an enormous burden to patients, it challenges wound care professionals and causes a great financial cost to health system. Considering the absence of effective treatments for chronic wounds, our aim was to better understand the pathophysiology of tissue repair in diabetes in order to find alternative strategies to accelerate wound healing. Nucleotides have been described as extracellular signaling molecules in different inflammatory processes, including tissue repair. Adenosine-5'-diphosphate (ADP) plays important roles in vascular and cellular response and is immediately released after tissue injury, mainly from platelets. However, despite the well described effect on platelet aggregation during inflammation and injury, little is known about the role of ADP on the multiple steps of tissue repair, particularly in skin wounds. Therefore, we used the full-thickness excisional wound model to evaluate the effect of local ADP application in wounds of diabetic mice. ADP accelerated cutaneous wound healing, improved new tissue formation, and increased both collagen deposition and transforming growth factor-β (TGF-β) production in the wound. These effects were mediated by P2Y12 receptor activation since they were inhibited by Clopidogrel (Clop) treatment, a P2Y12 receptor antagonist. Furthermore, P2Y1 receptor antagonist also blocked ADP-induced wound closure until day 7, suggesting its involvement early in repair process. Interestingly, ADP treatment increased the expression of P2Y12 and P2Y1 receptors in the wound. In parallel, ADP reduced reactive oxygen species (ROS) formation and tumor necrosis factor-α (TNF-α) levels, while increased IL-13 levels in the skin. Also, ADP increased the counts of neutrophils, eosinophils, mast cells, and gamma delta (γδ) T cells (Vγ4+ and Vγ5+ cells subtypes of γδ+ T cells), although reduced regulatory T (Tregs) cells in the lesion. In accordance, ADP increased fibroblast proliferation and migration, myofibroblast differentiation, and keratinocyte proliferation. In conclusion, we provide strong evidence that ADP acts as a pro-resolution mediator in diabetes-associated skin wounds and is a promising intervention target for this worldwide problem.

Targeted knockdown of the adenosine A2A receptor by lipid NPs rescues the chemotaxis of head and neck cancer memory T cells

In solid malignancies, including head and neck squamous cell carcinoma (HNSCC), the immunosuppressive molecule adenosine, which accumulates in the tumor, suppresses cytotoxic CD8⁺ T cell functions including chemotaxis and tumor infiltration. Adenosine functions through binding to the adenosine A_2A receptor (A_2AR) present on T cells. In order to increase T cell migration into the tumor, the negative effect of adenosine must be abrogated. Systemic drug treatments targeting A_2AR are available; however, they could lead to negative toxicities due to the broad expression of this receptor. Herein, we developed a lipid nanoparticle (NP)-based targeted delivery approach to knock down A_2AR in T cells in order to increase their chemotaxis in the presence of adenosine. By using flow cytometry, immunofluorescence, qRT-PCR, and 3D-chemotaxis, we demonstrated that CD45RO-labeled nanoparticles delivering ADORA2A gene-silencing-RNAs decreased ADORA2A mRNA expression and rescued the chemotaxis of HNSCC CD8⁺ memory T cells. Overall, the data indicate that targeting the adenosine signaling pathway with lipid NPs is successful at suppressing the inhibitory effect of adenosine on the chemotaxis of HNSCC memory T cells, which could ultimately help increase T cell infiltration into the tumor.

Hyperhomocysteinemia and Cardiovascular Disease: Is the Adenosinergic System the Missing Link?

The influence of hyperhomocysteinemia (HHCy) on cardiovascular disease (CVD) remains unclear. HHCy is associated with inflammation and atherosclerosis, and it is an independent risk factor for CVD, stroke and myocardial infarction. However, homocysteine (HCy)-lowering therapy does not affect the inflammatory state of CVD patients, and it has little influence on cardiovascular risk. The HCy degradation product hydrogen sulfide (H2S) is a cardioprotector. Previous research proposed a positive role of H2S in the cardiovascular system, and we discuss some recent data suggesting that HHCy worsens CVD by increasing the production of H2S, which decreases the expression of adenosine A2A receptors on the surface of immune and cardiovascular cells to cause inflammation and ischemia, respectively.

A1 and A2A Receptors Modulate Spontaneous Adenosine but Not Mechanically Stimulated Adenosine in the Caudate

Adenosine is a neuromodulator, and rapid increases in adenosine in the brain occur spontaneously or after mechanical stimulation. However, the regulation of rapid adenosine by adenosine receptors is unclear, and understanding it would allow better manipulation of neuromodulation. The two main adenosine receptors in the brain are A₁ receptors, which are inhibitory, and A_2A receptors, which are excitatory. Here, we investigated the regulation of spontaneous adenosine and mechanically stimulated adenosine by adenosine receptors, using global A₁ or A_2A knockout mice. Results were compared in vivo and in brain slices' models. A₁ KO mice have increased frequency of spontaneous adenosine events, but no change in the average concentration of an event, while A_2A KO mice had no change in frequency but increased average event concentration. Thus, both A₁ and A_2A self-regulate spontaneous adenosine release; however, A₁ acts on the frequency of events, while A_2A receptors regulate concentration. The trends are similar both in vivo and slices, so brain slices are a good model system to study spontaneous adenosine release. For mechanically stimulated adenosine, there was no effect of A₁ or A_2A KO in vivo, but in brain slices, there was a significant increase in concentration evoked in A₁KO mice. Mechanically stimulated release was largely unregulated by A₁ and A_2A receptors, likely because of a different release mechanism than spontaneous adenosine. Thus, A₁ receptors affect the frequency of spontaneous adenosine transients, and A_2A receptors affect the concentration. Therefore, future studies could probe drug treatments targeting A₁ and A_2A receptors to increase rapid adenosine neuromodulation.

Polydeoxyribonucleotide-delivering therapeutic hydrogel for diabetic wound healing

Patients with diabetes experience delayed wound healing because of the uncontrolled glucose level in their bloodstream, which leads to impaired function of white blood cells, poor circulation, decreased production and repair of new blood vessels. Treatment using polydeoxyribonucleotide (PDRN), which is a DNA extracted from the sperm cells of salmon, has been introduced to accelerate the healing process of diabetic wounds. To accelerate the wound-healing process, sustained delivery of PDRN is critical. In this study, taking advantage of the non-invasive gelation property of alginate, PDRN was loaded inside the hydrogel (Alg-PDRN). The release behavior of PDRN was altered by controlling the crosslinking density of the Alg hydrogel. The amount of PDRN was the greatest inside the hydrogel with the highest crosslinking density because of the decreased diffusion. However, there was an optimal degree of crosslinking for the effective release of PDRN. In vitro studies using human dermal fibroblasts and diabetes mellitus fibroblasts and an in ovo chorioallantoic membrane assay confirmed that the Alg-PDRN hydrogel effectively induced cell proliferation and expression of angiogenic growth factors and promoted new blood vessel formation. Its effectiveness for accelerated diabetic wound healing was also confirmed in an in-vivo animal experiment using a diabetic mouse model.

Advantages in Wound Healing Process in Female Mice Require Upregulation A2A-Mediated Angiogenesis under the Stimulation of 17β-Estradiol

Estrogenic steroids and adenosine A_2A receptors promote the wound healing and angiogenesis processes. However, so far, it is unclear whether estrogen may regulate the expression and pro-angiogenic activity of A_2A receptors. Using in vivo analyses, we showed that female wild type (WT) mice have a more rapid wound healing process than female or male A_2A-deficient mice (A_2AKO) mice. We also found that pulmonary endothelial cells (mPEC) isolated from female WT mice showed higher expression of A_2A receptor than mPEC from male WT mice. mPEC from female WT mice were more sensitive to A_2A-mediated pro-angiogenic response, suggesting an ER and A_2A crosstalk, which was confirmed using cells isolated from A_2AKO. In those female cells, 17β-estradiol potentiated A_2A-mediated cell proliferation, an effect that was inhibited by selective antagonists of estrogen receptors (ER), ERα, and ERβ. Therefore, estrogen regulates the expression and/or pro-angiogenic activity of A_2A adenosine receptors, likely involving activation of ERα and ERβ receptors. Sexual dimorphism in wound healing observed in the A_2AKO mice process reinforces the functional crosstalk between ER and A_2A receptors.

The effects of polydeoxyribonucleotide on wound healing and tissue regeneration: a systematic review of the literature

Aim: The present study evaluated the effects of polydeoxyribonucleotide (PDRN) on tissue regeneration, paying special attention to the molecular mechanisms that underlie its tissue remodeling actions to better identify its effective therapeutic potential in wound healing. Materials & methods: Strategic searches were conducted through MEDLINE/PubMed, Google Scholar, Scopus, Web of Science and the Cochrane Central Register of Controlled Trials, from their earliest available dates to March 2020. The studies were included with the following eligibility criteria: studies evaluating tissue regeneration, and being an in vitro, in vivo and clinical study. Results: Out of more than 90 articles, 34 fulfilled the eligibility criteria. All data obtained proved the ability of PDRN in promoting a physiological tissue repair through salvage pathway and adenosine A2A receptor activation. Conclusion: Up to date PDRN has proved promising results in term of wound regeneration, healing time and absence of side effects.

Adjuvant drug-assisted bone healing: Part III - Further strategies for local and systemic modulation

In this third in a series of reviews on adjuvant drug-assisted bone healing, further approaches aiming at influencing the healing process are discussed. Local and systemic modulation of bone metabolism is pursued with use of a number of drugs with completely different indications, which are characterized by a pleiotropic spectrum of action. These include drugs used to treat lipid disorders (HMG-CoA reductase inhibitors), hypertension (ACE inhibitors), osteoporosis (bisphosphonates), cancer (proteasome inhibitors) and others. Potential applications to enhance bone healing are discussed.

Mécanisme d'action du méthotrexate dans le traitement de la polyarthrite rhumatoïde

Le méthotrexate est utilisé dans le traitement de la polyarthrite rhumatoïde (PR) depuis les années 1980 et est souvent à ce jour le médicament de première intention pour le traitement de la PR. Dans cette revue, nous examinons plusieurs hypothèses pour expliquer le mécanisme à l'origine de l'efficacité du méthotrexate dans la PR. Celles-ci comprennent l'antagonisme du folate, la signalisation par l'adénosine, la génération d'espèces réactives de l'oxygène (ROS), la diminution des molécules d'adhérence, la modification des profils cytokiniques et l'inhibition des polyamines, entre autres. Actuellement, la signalisation par l'adénosine est probablement l'explication la plus largement acceptée du mécanisme du méthotrexate dans la PR, car le méthotrexate augmente les taux d'adénosine et suite à l'engagement de l'adénosine avec ses récepteurs extracellulaires, une cascade intracellulaire est activée et favorise un état antiinflammatoire global. Outre ces hypothèses, nous examinons le mécanisme du méthotrexate dans la PR sous l'angle de ses effets indésirables et considérons certains des nouveaux marqueurs génétiques de l'efficacité et de la toxicité du méthotrexate dans la PR. Enfin, nous discutons brièvement du mécanisme du méthotrexate en association avec un traitement de la PR par un inhibiteur du TNF-. En fin de compte, en trouvant une explication claire de la voie et du mécanisme conduisant à l'efficacité du méthotrexate dans la PR, il pourrait exister un moyen de formuler des thérapies plus puissantes avec moins d'effets secondaires.

In Vivo Sequestration of Innate Small Molecules to Promote Bone Healing

Approaches that enable innate repair mechanisms hold great potential for tissue repair. Herein, biomaterial-assisted sequestration of small molecules is described to localize pro-regenerative signaling at the injury site. Specifically, a synthetic biomaterial containing boronate molecules is designed to sequester adenosine, a small molecule ubiquitously present in the human body. The biomaterial-assisted sequestration of adenosine leverages the transient surge of extracellular adenosine following injury to prolong local adenosine signaling. It is demonstrated that implantation of the biomaterial patch following injury establishes an in situ stockpile of adenosine, resulting in accelerated healing by promoting both osteoblastogenesis and angiogenesis. The adenosine content within the patch recedes to the physiological level as the tissue regenerates. In addition to sequestering endogenous adenosine, the biomaterial is also able to deliver exogenous adenosine to the site of injury, offering a versatile solution to utilizing adenosine as a potential therapeutic for tissue repair.

Overcoming immunotherapeutic resistance by targeting the cancer inflammation cycle

Inflammation is a hallmark of cancer and supports tumor growth, proliferation, and metastasis, but also inhibits T cell immunosurveillance and the efficacy of immunotherapy. The biology of cancer inflammation is defined by a cycle of distinct immunological steps that begins during disease conception with the release of inflammatory soluble factors. These factors communicate with host organs to trigger bone marrow mobilization of myeloid cells, trafficking of myeloid cells to the tumor, and differentiation of myeloid cells within the tumor bed. Tumor-infiltrating myeloid cells then orchestrate an immunosuppressive microenvironment and assist in sustaining a vicious cycle of inflammation that co-evolves with tumor cells. This Cancer-Inflammation Cycle acts as a rheostat or "inflammostat" that impinges upon T cell immunosurveillance and prevents the development of productive anti-tumor immunity. Here, we define the major nodes of the Cancer-Inflammation Cycle and describe their impact on T cell immunosurveillance in cancer. Additionally, we discuss emerging pre-clinical and clinical data suggesting that intervening upon the Cancer-Inflammation Cycle will be a necessary step for broadening the potential of immunotherapy in cancer.

Effect of Polydeoxyribonucleotide on Chondrocutaneous Composite Grafts Survival

BACKGROUND

A composite graft is considered the best choice for facial reconstruction because of proper texture, color, and simple surgical techniques. However, due to revascularization by the bridging phenomenon, it has limitations with unpredictable survival rates and can be applied only to small defects. Polydeoxyribonucleotide (PDRN) plays an important role in multiple vascular processes such as angiogenesis via production of a vascular endothelial growth factor and by providing an anti-inflammatory effect by reducing pro-inflammatory cytokines through the adenosine A2 receptor stimulation. Thus, here, we investigated PDRN as a supportive method to improve survival of composite grafts.

METHODS

Chondrocutaneous composite grafts were applied to both ears of 20 New Zealand White rabbits. The grafts were then rotated and returned to their positions to prevent the original blood flow from the base of the grafts. On postoperative days 1, 3, 6, 9, and 12, PDRN was injected intradermally into the experimental group (20 ears) and normal saline was injected into the control group (20 ears) to exclude bias of pressure effect. After 12 days, graft survival and cutaneous blood flow were examined under laser speckle contrast imaging.

RESULTS

Gross observation indicated that the graft viability in the PDRN group was significantly higher than that in the control group (p < 0.05). Through laser speckle contrast imaging, signal intensity increased from the periphery and progressed centrally with treatment.

CONCLUSION

Our findings suggest that PDRN may increase blood flow around at the base of the graft, restore the perfusion, and improve the survival of the composite grafts.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Innate immune cell-epithelial crosstalk during wound repair

Skin and intestinal epithelial barriers play a pivotal role in protecting underlying tissues from harsh external environments. The protective role of these epithelia is, in part, dependent on a remarkable capacity to restore barrier function and tissue homeostasis after injury. In response to damage, epithelial wounds repair by a series of events that integrate epithelial responses with those of resident and infiltrating immune cells including neutrophils and monocytes/macrophages. Compromise of this complex interplay predisposes to development of chronic nonhealing wounds, contributing to morbidity and mortality of many diseases. Improved understanding of crosstalk between epithelial and immune cells during wound repair is necessary for development of better pro-resolving strategies to treat debilitating complications of disorders ranging from inflammatory bowel disease to diabetes. In this Review we focus on epithelial and innate immune cell interactions that mediate wound healing and restoration of tissue homeostasis in the skin and intestine.

Polydeoxyribonucleotides Improve Diabetic Wound Healing in Mouse Animal Model for Experimental Validation

Background

Wound healing mechanisms is believed to have effects similar to wound healing disorders in diabetic patients, including abnormal inflammatory cells, angiogenesis disorders, and reduced collagen synthesis. Therefore, reestablishment of structural and promoted angiogenesis could be beneficial to promote wound healing process.

Objective

Therefore, we investigated whether the polydeoxyribonucleotide (PDRN) that was self-production in Korea, could be useful as an intradermal injection for promoting wound healing. Also, we validate for wound healing effect of PDRN using healing-impaired (db/db) mice.

Methods

In this study, we confirmed the effects of PDRN by creating wound models in in vitro and in vivo model. Using an in vitro wound healing assay, we observed that PDRN stimulated closure of wounded monolayers of human fibroblast cells. PDRN (8.25 mg/ml) or phosphate-buffered saline (0.9% NaCl) was injected once daily into the dermis adjacent to the wound for 12 days after skin injury.

Results

Time course observations revealed that mice treated with PDRN showed accelerated wound closure and epidermal and dermal regeneration, enhanced angiogenesis. The wound area and depth decreased at 3, 6, 9, and 12 days after skin injury. Histological evaluation showed an increase of vascular endothelial growth factor, CD31, and collagen fibers in the PDRN group compared with the control group, indicating that PDRN was effective in the treatment of delayed wound healing caused by diabetes.

Conclusion

This study suggests that our PDRN has a wound healing effect in transgenic animal models with cells and diabetes through angiogenesis.

Adenosine kinase inhibition protects against cisplatin-induced nephrotoxicity

Numerous studies have demonstrated that several mechanisms, including oxidative stress, DNA damage, and inflammatory responses, are closely linked to cisplatin-induced nephrotoxicity. Adenosine, emerging as a key regulatory molecule, is mostly protective in the pathophysiology of inflammatory diseases. A previous study showed that some of the adenosine receptors led to renal protection against ischemia-reperfusion injury. However, these adenosine receptor agonists lack a useful therapeutic index due to cardiovascular side effects. We hypothesized that inhibition of adenosine kinase (ADK) might exacerbate extracellular adenosine levels to reduce cisplatin-induced renal injury. In the present study, pretreatment with the ADK inhibitor ABT-702 could markedly attenuate cisplatin-induced acute kidney injury, tubular cell apoptosis, oxidative stress, and inflammation in the kidneys. Consistent with in vivo results, inhibition of ADK suppressed cisplatin-induced apoptosis, reactive oxygen species production, and inflammation in HK2 cells. Additionally, the protective effect of ADK inhibition was abolished by A1 or A2B adenosine receptor antagonist and enhanced by A2A or A3 adenosine receptor antagonist. Collectively, the results suggest that inhibition of ADK might increase extracellular adenosine levels, which inhibited cisplatin-induced oxidative stress and inflammation via A1 and A2B adenosine receptors, finally suppressing cisplatin-induced cell apoptosis. Pharmacological therapies based on ADK will be of potential use in therapy of cisplatin-induced nephrotoxicity.

Multiple adenosine receptor subtypes stimulate wound healing in human EA.hy926 endothelial cells

Wound healing is an important outcome of tissue damage and can be stimulated by adenosine released from cells during events such as tissue injury, ischaemia or tumour growth. The aim of this research was to determine the potency and efficacy of adenosine A₁, A_2A and A_2B receptor agonists on the rate of wound healing and cell proliferation in human EA.hy926 endothelial cells. Real-time PCR data showed that only adenosine A₁, A_2A and A_2B receptor mRNA were expressed in this cell line. All three adenosine receptor agonists, CPA, CGS21680 and NECA, significantly increased the rate of wound healing in human EAhy926 endothelial cells with the following order of potency CGS21680>CPA>NECA and efficacy CPA>NECA>CGS21680. The selective adenosine A₁, A_2A and A_2B receptor antagonists, DPCPX, ZM241385 and MRS1754 (all at 10 nM), reversed the effects of their respective agonists. EAhy926 endothelial cell proliferation was also significantly increased with the adenosine A₁ and A_2B receptor agonists, CPA and NECA. Western blot analysis demonstrated that adenosine A_2A and A₁ receptor protein levels were highly expressed compared with the adenosine A_2B receptors in the EAhy926 endothelial cell lines. While all three adenosine A₁, A_2A and A_2B receptor subtypes contribute to cell proliferation and wound healing in human EAhy926 endothelial cells, treatments selectively targeting receptor subtypes may further enhance wound healing.

Adenosine A2a receptor promotes lymphangiogenesis and lymph node metastasis

The formation of new lymphatic vessels, or lymphangiogenesis, is a critical step of the tissue repair program. In pathological conditions involving chronic inflammation or tumorigenesis, this process is often dysregulated and can contribute to disease progression. Yet, lymphangiogenesis is still incompletely understood. In this study, we identified A2a adenosinergic signaling as an important regulator of inflammatory and tumor-associated lymphangiogenesis. Using Adora2a (A2a)-deficient mice, we demonstrated that A2a signaling was involved in the formation of new lymphatic vessels in the context of peritoneal inflammation. We also demonstrated that tumor-associated and sentinel lymph node lymphangiogenesis were impaired in A2a-deficient mice, protecting them from lymph node metastasis. Notably, A2a signaling in both hematopoietic and non-hematopoietic cells contributed to sentinel lymph node metastasis. In A2a-deficient tumor-draining lymph nodes, impaired lymphangiogenesis was associated with a reduced accumulation of B cells and decreased VEGF-C levels. Supporting a role for non-hematopoietic A2a signaling, we observed that primary murine lymphatic endothelial cells (LEC) predominantly expressed A2a receptor and that A2a signaling blockade altered LEC capillary tube formation in vitro. Finally, we observed that Adora2a, Nt5e and Entpd1 gene expression positively correlated with Lyve1, Pdpn and Vegfc in several human cancers, thereby supporting the notion that adenosine production and A2a receptor activation might promote lymphangiogenesis in human tumors. In conclusion, our study highlights a novel pathway regulating lymphangiogenesis and further supports the use of A2a or adenosine blocking agents to inhibit pathological lymphangiogenesis in cancers and block the dissemination of tumor cells through the lymphatic system.

A2AR Antagonism with CPI-444 Induces Antitumor Responses and Augments Efficacy to Anti-PD-(L)1 and Anti-CTLA-4 in Preclinical Models

Adenosine signaling through A2A receptors (A2AR) expressed on immune cells suppresses antitumor immunity. CPI-444 is a potent, selective, oral A2AR antagonist. Blockade of A2AR with CPI-444 restored T-cell signaling, IL2, and IFNγ production that were suppressed by adenosine analogues in vitro CPI-444 treatment led to dose-dependent inhibition of tumor growth in multiple syngeneic mouse tumor models. Concentrations of extracellular adenosine in the tumor microenvironment, measured using microdialysis, were approximately 100-150 nmol/L and were higher than corresponding subcutaneous tissue. Combining CPI-444 with anti-PD-L1 or anti-CTLA-4 treatment eliminated tumors in up to 90% of treated mice, including restoration of immune responses in models that incompletely responded to anti-PD-L1 or anti-CTLA-4 monotherapy. Tumor growth was fully inhibited when mice with cleared tumors were later rechallenged, indicating that CPI-444 induced systemic antitumor immune memory. CD8⁺ T-cell depletion abrogated the efficacy of CPI-444 with and without anti-PD-L1 treatment, demonstrating a role for CD8⁺ T cells in mediating primary and secondary immune responses. The antitumor efficacy of CPI-444 with and without anti-PD-L1 was associated with increased T-cell activation, a compensatory increase in CD73 expression, and induction of a Th1 gene expression signature consistent with immune activation. These results suggest a broad role for adenosine-mediated immunosuppression in tumors and justify the further evaluation of CPI-444 as a therapeutic agent in patients with solid tumors. Cancer Immunol Res; 6(10); 1136-49. ©2018 AACR.

Methotrexate mechanism in treatment of rheumatoid arthritis

Methotrexate has been used in treatment of rheumatoid arthritis (RA) since the 1980s and to this day is often the first line medication for RA treatment. In this review, we examine multiple hypotheses to explain the mechanism of methotrexate efficacy in RA. These include folate antagonism, adenosine signaling, generation of reactive oxygen species (ROS), decrease in adhesion molecules, alteration of cytokine profiles, and polyamine inhibition amongst some others. Currently, adenosine signaling is probably the most widely accepted explanation for the methotrexate mechanism in RA given that methotrexate increases adenosine levels and on engagement of adenosine with its extracellular receptors an intracellular cascade is activated promoting an overall anti-inflammatory state. In addition to these hypotheses, we examine the mechanism of methotrexate in RA from the perspective of its adverse effects and consider some of the newer genetic markers of methotrexate efficacy and toxicity in RA. Lastly, we briefly discuss the mechanism of additive methotrexate in the setting of TNF-α inhibitor treatment of RA. Ultimately, finding a clear explanation for the pathway and mechanism leading to methotrexate efficacy in RA, there may be a way to formulate more potent therapies with fewer side effects.

Extracellular adenosine: a critical signal in liver fibrosis

Extracellular adenosine nucleoside is a potent, endogenous mediator that signals through specific G protein-coupled receptors, and exerts pleiotropic effects on liver physiology, in health and disease. Particularly, adenosinergic or adenosine-mediated signaling pathways impact the progression of hepatic fibrosis, a common feature of chronic liver diseases, through regulation of matrix deposition by liver myofibroblasts. This review examines the current lines of evidence on adenosinergic regulation of liver fibrosis and myofibroblasts, identifies unanswered research questions, and proposes important future areas of investigation.

Polydeoxyribonucleotide improves tendon healing following achilles tendon injury in rats

Tendon injuries are major musculoskeletal disorders. Polydeoxyribonucleotide activates the adenosine receptor subtype A2A, resulting in tissue growth and neogenesis. This experimental study confirms that polydeoxyribonucleotide can improve secretion of various growth factors, promote collagen synthesis, and restore tensile strength of the Achilles tendon in a rat model with Achilles tendon injury. Thirty-six male Sprague-Dawley rats, aged 7 weeks, were divided into two groups, and the Achilles tendon was transected and repaired using the modified Kessler's method. In the experimental group (n = 18), the rats received daily intraperitoneal administration of polydeoxyribonucleotide (8 mg/kg/day for 1, 2, or 4 weeks). The control groups received the same amount of normal saline. The rats were euthanized at 1, 2, and 4 weeks, and tissues from the repair site were harvested. The cross-sectional area of the tendon was significantly increased at 2 and 4 weeks in polydeoxyribonucleotide group (p = 0.008 and p = 0.017, respectively). Moreover, tendons in the polydeoxyribonucleotide group were more resistant to mechanical stress at 2 and 4 weeks (p = 0.041 and p = 0.041, respectively). The staining levels of collagen type I in the experimental group were significantly stronger at 2 and 4 weeks (p = 0.026 and p = 0.009, respectively). Furthermore, higher expression levels of fibroblast growth factor, vascular endothelial growth factor, and transforming growth factor β1 were detected in the experimental group at 4 weeks (p = 0.041, p = 0.026, and p = 0.041, respectively). This study confirms that polydeoxyribonucleotide can improve the tensile strength of the rats' Achilles tendon following injury and repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1767-1776, 2018.

The promotion of tissue engineering blood vessel patency by CGS21680 through regulating pro-inflammatory activities of endothelial progenitor cell

The mobilization and homing of endothelial progenitor cells (EPCs) contribute to the rapid endothelialization of tissue engineering blood vessel (TEBV). Inflammation can affect TEBV patency, and monocytes/macrophages (MM) are the main effector cells. But it is not clear how EPCs interact with MM after TEBV transplantation. Our results showed acellular materials would not directly cause acute and severe inflammatory responses but activate E-selectin expression in homing EPCs, gradually promoting the polarization of MM to the M1. Adenosine A2a receptor agonist CGS21680 promoted the secretion of more proangiogenic factors from MM, inducing EPC migration and mobilization. CGS21680 could inhibit MM polarization to the M1 type through the down-regulation of EPC proinflammatory molecules, such as E-selectin. Chitosan/(2-hydroxypropyl)-β-cyclodextrin nanoparticles were prepared to control the release of CGS-21680 and then modified to TEBVs through layer-by-layer assembly. Animal experiments showed that this TEBV can maintain patency for 6 months and good endothelialization was observed. In summary, our results showed the regulation of EPC pro-inflammatory activities is a new approach to enhance TEBV patency. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2634-2642, 2018.

Combination therapy with polydeoxyribonucleotide and proton pump inhibitor enhances therapeutic effectiveness for gastric ulcer in rats

AIMS

The main action of proton pump inhibitors (PPIs) is to inhibit gastric acid secretion, and PPIs are widely used to treat gastric ulcer (GU). However, if the action of promoting gastric mucosal regeneration is added, the effectiveness of GU treatment can be enhanced. Thus, in order to improve the therapeutic effect on GU, we tried to develop combination therapy promoting regeneration in injured tissue besides suppressing gastric acid secretion.

MAIN METHODS

Polydeoxyribonucleotide (PDRN) was selected to evaluate tissue regeneration, and pantoprazole was chosen as one of the PPIs. GU was induced by oral administration of indomethacin once a day for 7 days. Rats in drug-administered groups were intraperitoneally injected with 100 μL normal saline, containing each drug at the indicated concentration, once a day for 14 days after inducing GU.

KEY FINDINGS

PDRN and PPI combination therapy potently improved tissue regeneration and inhibited production of pro-inflammatory cytokines. PDRN treatment with or without PPI increased the concentration of cyclic adenosine-3,5'-monophosphate (cAMP) and the ratio of phosphorylated cAMP response element-binding protein (p-CREB) to cAMP response element-binding protein (CREB). PDRN treatment with or without PPI also increased the expressions of vascular endothelial growth factor (VEGF) and adenosine A_2A receptor.

SIGNIFICANCE

PDRN and PPI combination therapy showed more potent therapeutic effect on GU compared to the PDRN monotherapy or PPI monotherapy. The excellent therapeutic effect of PDRN and PPI combination therapy on GU appeared by promoting regeneration of damaged tissue as well as inhibiting gastric acid secretion.

Comparison of wound healing effects between Oncorhynchus keta-derived polydeoxyribonucleotide (PDRN) and Oncorhynchus mykiss-derived PDRN

Background

Polydeoxyribonucleotide (PDRN) influencing cellular growth and differentiation is recognized to promote wound healing by stimulating tissue repair. Although PDRN can be extracted from human placentas, PDRN medications have recently been extracted from the semen of trout (Oncorhynchus mykiss) and salmon (Oncorhynchus keta). The present study was designed to evaluate the wound healing effects of O. keta-derived PDRN for injection (Rejuvenex) and PDRN cream (Rejuvenex Cream) in comparison with those of O. mykiss-derived PDRN injection (Placentex).

Methods

Full-thickness skin defects were made on the back of mice (n=60). The mice were divided into the following four groups according to the dressing used for the wounds: O. mykiss-derived PDRN injection group, O. keta-derived PDRN injection group, O. keta-derived PDRN cream group, and normal saline soaked dressing group (control group). We analyzed the gross findings, wound sizes, histological findings, immunohistochemistry and enzyme-linked immunosorbent assays for the groups immediately after the treatment, and again after 4, 7, and 10 days of treatment.

Results

The wound healing effects were the greatest in the O. keta-derived PDRN injection and O. mykiss-derived PDRN injection groups, which showed similar scores, followed by the O. keta-derived cream and normal saline soaked dressing groups.

Conclusion

The injection of PDRN extracted from O. keta was found to be as effective at healing full-thickness skin defects as the O. mykiss-derived PDRN injection, which is currently used in the clinic. Moreover, the O. keta-derived PDRN injection was also found to reduce the time required for wound healing.

Engineering Tissues without the Use of a Synthetic Scaffold: A Twenty-Year History of the Self-Assembly Method

Twenty years ago, Dr. François A. Auger, the founder of the Laboratory of Experimental Organogenesis (LOEX), introduced the self-assembly technique. This innovative technique relies on the ability of dermal fibroblasts to produce and assemble their own extracellular matrix, differing from all other tissue-engineering techniques that use preformed synthetic scaffolds. Nevertheless, the use of the self-assembly technique was limited for a long time due to its main drawbacks: time and cost. Recent scientific breakthroughs have addressed these limitations. New protocol modifications that aim at increasing the rate of extracellular matrix formation have been proposed to reduce the production costs and laboratory handling time of engineered tissues. Moreover, the introduction of vascularization strategies in vitro permits the formation of capillary-like networks within reconstructed tissues. These optimization strategies enable the large-scale production of inexpensive native-like substitutes using the self-assembly technique. These substitutes can be used to reconstruct three-dimensional models free of exogenous materials for clinical and fundamental applications.

Polydeoxyribonucleotide Improves Peripheral Tissue Oxygenation and Accelerates Angiogenesis in Diabetic Foot Ulcers

BACKGROUND

Polydeoxyribonucleotide (PDRN) is known to have anti-inflammatory and angiogenic effects and to accelerate wound healing. The aim of this study was to investigate whether PDRN could improve peripheral tissue oxygenation and angiogenesis in diabetic foot ulcers.

METHODS

This was a prospective randomized controlled clinical trial. Twenty patients with a non-healing diabetic foot ulcer were randomly distributed into a control group (n=10) and a PDRN group (n=10). Initial surgical debridement and secondary surgical procedures such as a split-thickness skin graft, primary closure, or local flap were performed. Between the initial surgical debridement and secondary surgical procedures, 0.9% normal saline (3 mL) or PDRN was injected for 2 weeks by the intramuscular (1 ampule, 3 mL, 5.625 mg, 5 days per week) and perilesional routes (1 ampule, 3 mL, 5.625 mg, 2 days per week). Transcutaneous oxygen tension (TcPO₂) was evaluated using the Periflux System 5000 with TcPO₂/CO₂ unit 5040 before the injections and on days 1, 3, 7, 14, and 28 after the start of the injections. A pathologic review (hematoxylin and eosin stain) of the debrided specimens was conducted by a pathologist, and vessel density (average number of vessels per visual field) was calculated.

RESULTS

Compared with the control group, the PDRN-treated group showed improvements in peripheral tissue oxygenation on day 7 (P<0.01), day 14 (P<0.001), and day 28 (P<0.001). The pathologic review of the specimens from the PDRN group showed increased angiogenesis and improved inflammation compared with the control group. No statistically significant difference was found between the control group and the PDRN group in terms of vessel density (P=0.094). Complete healing was achieved in every patient.

CONCLUSIONS

In this study, PDRN improved peripheral tissue oxygenation. Moreover, PDRN is thought to be effective in improving inflammation and angiogenesis in diabetic foot ulcers.

Therapeutic potency of pharmacological adenosine receptor agonist/antagonist in angiogenesis, current status and perspectives

OBJECTIVES

Adenosine concentration significantly increases in tumour microenvironment contributing to tumorigenic processes including cell proliferation, survival, invasion and of special interest in this review angiogenesis.

KEY FINDINGS

This review summarizes the role of pharmacological adenosine receptor agonist and antagonist in regulating angiogenesis for a better understanding and hence a better management of angiogenesis-associated disorders.

SUMMARY

Depending upon the pharmacological characteristics of adenosine receptor subtypes, adenosine elicits anti- or pro-angiogenic responses in stimulated cells. Inhibition of the stimulatory effect of adenosine signalling on angiogenesis using specific pharmacological adenosine receptor agonist, and antagonist is a potentially novel strategy to suppress angiogenesis in tumours.

Endothelial adenosine A2a receptor-mediated glycolysis is essential for pathological retinal angiogenesis

Adenosine/adenosine receptor-mediated signaling has been implicated in the development of various ischemic diseases, including ischemic retinopathies. Here, we show that the adenosine A2a receptor (ADORA2A) promotes hypoxia-inducible transcription factor-1 (HIF-1)-dependent endothelial cell glycolysis, which is crucial for pathological angiogenesis in proliferative retinopathies. Adora2a expression is markedly increased in the retina of mice with oxygen-induced retinopathy (OIR). Endothelial cell-specific, but not macrophage-specific Adora2a deletion decreases key glycolytic enzymes and reduces pathological neovascularization in the OIR mice. In human primary retinal microvascular endothelial cells, hypoxia induces the expression of ADORA2A by activating HIF-2α. ADORA2A knockdown decreases hypoxia-induced glycolytic enzyme expression, glycolytic flux, and endothelial cell proliferation, sprouting and tubule formation. Mechanistically, ADORA2A activation promotes the transcriptional induction of glycolytic enzymes via ERK- and Akt-dependent translational activation of HIF-1α protein. Taken together, these findings advance translation of ADORA2A as a therapeutic target in the treatment of proliferative retinopathies and other diseases dependent on pathological angiogenesis.Pathological angiogenesis in the retina is a major cause of blindness. Here the authors show that adenosine receptor A2A drives pathological angiogenesis in the oxygen-induced retinopathy mouse model by promoting glycolysis in endothelial cells via the ERK/Akt/HIF-1α pathway, thereby suggesting new therapeutic targets for disease treatment.

Adenosine: An endogenous mediator in the pathogenesis of gynecological cancer

Extracellular concentration of adenosine increases in the hypoxic tumor microenvironment. Adenosine signaling regulates apoptosis, angiogenesis, metastasis, and immune suppression in cancer cells. Adenosine-induced cell responses depend upon different subtypes of adenosine receptors activation and type of cancer. Suppression of adenosine signaling via inhibition of adenosine receptors or adenosine generating enzymes including CD39 and CD73 on ovarian or cervical cancer cells is a potentially novel therapeutic approach for gynecological cancer patients. This review summarizes the role of adenosine in the pathogenesis of gynecological cancer for a better understanding and hence a better management of this disease.