High-mobility group box 1 fragment suppresses adverse post-infarction remodeling by recruiting PDGFRα-positive bone marrow cells

Pdgfrα+ stromal cells, a key regulator for tissue homeostasis and dysfunction in distinct organs

Pdgfrα+ stromal cells are a group of cells specifically expressing Pdgfrα, which may be mentioned with distinct names in different tissues. Importantly, the findings from numerous studies suggest that these cells share exactly similar biomarkers and properties, show complex functions in regulating the microenvironment, and are critical to tissue regeneration, repair, and degeneration. Comparing the similarities and differences between distinct tissue-resident Pdgfrα+ stromal cells is helpful for us to more comprehensively and deeply understand the behaviors of these cells and to explore some common regulating mechanisms and therapeutical targets. In this review, we summarize previous and current findings on Pdgfrα+ stromal cells in various tissues and discuss the crosstalk between Pdgfrα+ stromal cells and microenvironment.

HMGB1 in Septic Muscle Atrophy: Roles and Therapeutic Potential for Muscle Atrophy and Regeneration

Currently, the treatment of septic myopathy presents significant challenges with implications for increased mortality rates and prolonged hospitalizations. Effective therapeutic strategies for septic myopathy remain elusive, highlighting an urgent need for novel therapeutic approaches. High-mobility group box 1 (HMGB1) is a conserved nonhistone nuclear protein that is released passively from deceased cells or actively secreted by activated immune cells, influencing both infectious and noninfectious inflammatory responses. Studies have indicated that HMGB1 likely plays a pivotal role in the pathogenesis of septic myopathy by crucial pathways associated with muscle atrophy and contributing to muscle regeneration under certain conditions. This review aims to summarize the possible mechanisms of HMGB1 in muscle atrophy and its potential in muscle regeneration, providing a theoretical basis for HMGB1 treatment of septic myopathy. Research shows that the dual role of HMGB1 is related to its specific forms, which are influenced to varying degrees by environmental factors. HMGB1 is a key participant in septic muscle atrophy, whereas HMGB1 shows therapeutic potential in muscle regeneration. One key mechanism by which HMGB1 contributes to septic muscle atrophy is through the exacerbation of inflammation. HMGB1 can amplify the inflammatory response by promoting the release of pro-inflammatory cytokines, which further damages muscle tissue. HMGB1 is also involved in promoting cell death in sepsis, which contributes to muscle degradation. Another important mechanism is the regulation of protein degradation systems. HMGB1 can activate the ubiquitin-proteasome system and autophagy-lysosome pathway, both of which are crucial for the breakdown of muscle proteins during atrophy. Conversely, targeting HMGB1 has shown the potential to ameliorate muscle atrophy in various diseases. For instance, HMGB1 has been shown to promote muscle vascular regeneration, modify stem cell status and enhance stem cell migration and differentiation, all of which are beneficial for muscle repair and recovery. Pharmacological inhibition of HMGB1 has been explored, with several drugs demonstrating efficacy in reducing inflammation and muscle degradation in sepsis models. These findings suggest that HMGB1 inhibition could be a viable therapeutic approach for septic myopathy. However, the function of promoting muscle regeneration in septic myopathy needs further research. HMGB1 emerges as a promising therapeutic target for the treatment of muscle atrophy in sepsis. This review focuses on identifying the correlation between HMGB1 and septic myopathy, analysing the possible role of HMGB1 in disease development and examining the feasibility of HMGB1 as a therapeutic target.

High-mobility group box 1 fragment ameliorates chronic pancreatitis induced by caerulein in mice

BACKGROUND

Chronic pancreatitis (CP) is a progressive disease characterized by pancreatic fibrosis for which effective treatment options are lacking. Mesenchymal stem cells (MSCs) have shown potential for fibrosis treatment but face limitations in clinical application. The high-mobility group box 1 (HMGB1) fragment mobilizes MSCs from bone marrow into the blood and has emerged as a promising therapeutic agent for tissue regeneration in various pathological conditions. The aim of this study was to investigate the potential therapeutic effects of systemic administration of the HMGB1 fragment in a mouse model of CP.

METHODS

A caerulein-induced CP mouse model was used, and the HMGB1 fragment was administered by tail vein injection. Parameters such as body weight, pancreatic tissue damage, fibrosis, inflammatory cytokine expression, and collagen-related gene expression were evaluated using various assays, including immunohistochemistry, real-time PCR, serum analysis, and single-cell transcriptome analysis. And the migration of MSCs to the pancreas was evaluated using the parabiosis model.

RESULTS

Administration of the HMGB1 fragment was associated with significant improvements in pancreatic tissue damage and fibrosis. It suppressed the expression of inflammatory cytokines and activated platelet-derived growth factor receptor-α+ MSCs, leading to their accumulation in the pancreas. The HMGB1 fragment also shifted gene expression patterns associated with pancreatic fibrosis toward those of the normal pancreas. Systemic administration of the HMGB1 fragment demonstrated therapeutic efficacy in attenuating pancreatic tissue damage and fibrosis in a CP mouse model.

CONCLUSION

These findings highlight the potential of the HMGB1 fragment as a therapeutic target for the treatment of CP.

Treatment of Epidermolysis Bullosa and Future Directions: A Review

Epidermolysis bullosa (EB) comprises rare genetic disorders characterized by skin and mucosal membrane blistering induced by mechanical trauma. Molecularly, pathogenic variants affect genes encoding proteins crucial for epidermal-dermal adhesion and stability. Management of severe EB is multidisciplinary, focusing on wound healing support, ensuring that patients thrive, and complication treatment. Despite extensive research over 30 years, novel therapeutic approaches face challenges. Gene therapy and protein therapy struggle with efficacy, while regenerative cell-based therapies show limited effects. Drug repurposing to target various pathogenic mechanisms has gained attention, as has in vivo gene therapy with drugs for dystrophic and junctional EB that were recently approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMA). However, their high cost limits global accessibility. This review examines therapeutic advancements made over the past 5 years, exploiting a systematic literature review and clinical trial data.

Regenerative medicine in cardiovascular disease

Owing to the rapid increase in the number of people with severe heart failure, regenerative medicine is anticipated to play a role in overcoming the limitations inherent in existing surgical interventions. There are essentially two types of cardiac regenerative therapies for a failing heart. Cellular regenerative therapies using various stem cells improve the functional recovery of the heart mainly by cytokine paracrine effects. The implantation of induced pluripotent stem cell-derived cardiomyocytes can contribute not only to the inhibition of adverse heart remodeling by paracrine effects but also to the supply of newly born functional myocytes with the recipient myocardium as "mechanically working cells." Cell transplantation, including autologous myoblast transplantation, reduces heart failure exacerbations and benefits patients without the need for other treatment options. Although cellular therapy is currently the mainstream approach, it requires an in-house cell-processing center with an aseptic environment. In addition, these stem cells are usually introduced via several invasive delivery methods, including intracoronary administration, and cellular sheet implantation. Simplifying the culture methods for these cells is a crucial problem that needs to be resolved. Drug-induced regenerative therapy is another option that enhances self-endogenous regenerative systems in the human body and does not require invasive methods or cell cultures. Therefore, drug-induced regenerative therapies may overcome the disadvantages of these cellular therapies. The purpose of this report is to summarize cell transplantation therapy in the cardiovascular system and regenerative therapy for heart failure using an autologous endogenous regenerative system.

Enhancement of tracheal cartilage regeneration by local controlled release of stromal cell-derived factor 1α with gelatin hydrogels and systemic administration of high-mobility group box 1 peptide

Introduction

This present study evaluated the effect of combination therapy with stromal cell-derived factor 1α (SDF-1α) and high-mobility group box 1 (HMGB1) peptide on the regeneration of tracheal injury in a rat model.

Methods

To improve this effect, SDF-1α was incorporated into a gelatin hydrogel, which was then applied to the damaged tracheal cartilage of rats for local release. Furthermore, HMGB1 peptide was repeatedly administered intravenously. Regeneration of damaged tracheal cartilage was evaluated in terms of cell recruitment.

Results

Mesenchymal stem cells (MSC) with C-X-C motif chemokine receptor 4 (CXCR4) were mobilized more into the injured area, and consequently the fastest tracheal cartilage regeneration was observed in the combination therapy group eight weeks after injury.

Conclusions

The present study demonstrated that combination therapy with gelatin hydrogel incorporating SDF-1α and HMGB1 peptide injected intravenously can enhance the recruitment of CXCR4-positive MSC, promoting the regeneration of damaged tracheal cartilage.

Gene-Modified Blister Fluid-Derived Mesenchymal Stromal Cells for Treating Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a genodermatosis caused by variants in COL7A1-encoded type VII collagen, a major component of anchoring fibrils. In this study, we developed an ex vivo gene therapy for RDEB using autologous mesenchymal stromal cells (MSCs). On the basis of our previous studies, we first attempted to isolate MSCs from the blister fluid of patients with RDEB and succeeded in obtaining cells with a set of MSC characteristics from all 10 patients. We termed these cells blister fluid-derived MSCs. Blister fluid-derived MSCs were genetically modified and injected into skins of type VII collagen-deficient neonatal mice transplanted onto immunodeficient mice, resulting in continuous and widespread expression of type VII collagen at the dermal-epidermal junction, particularly when administered into blisters. When injected intradermally, the efforts were not successful. The gene-modified blister fluid-derived MSCs could be cultured as cell sheets and applied to the dermis with an efficacy equivalent to that of intrablister administration. In conclusion, we successfully developed a minimally invasive and highly efficient ex vivo gene therapy for RDEB. This study shows the successful application of gene therapy in the RDEB mouse model for both early blistering skin and advanced ulcerative lesions.

High-mobility group box 1 accelerates distraction osteogenesis healing via the recruitment of endogenous stem/progenitor cells

BACKGROUND AIMS

While distraction osteogenesis (DO) achieves substantial bone regeneration, prolonged fixation may lead to infections. Existing stem cell and physical therapies have limitations, requiring the development of novel therapeutic approaches. Here, we evaluated high-mobility group box 1 (HMGB1) as a novel therapeutic target for DO treatment.

METHODS

Micro-computed tomography (Micro-CT) analysis and histological staining of samples obtained from tibial DO model mice was performed. Transwell migration, wound healing, and proliferation assays were also performed on cultured human mesenchymal stem cells (hMSCs) and human umbilival vein endothelial cells (HUVECs). Tube formation assay was performed on HUVECs, whereas osteogenic differentiation assay was performed on hMSCs.

RESULTS

Micro-CT analysis and histological staining of mouse samples revealed that HMGB1 promotes bone regeneration during DO via the recruitment of PDGFRα and Sca-1 positve (PαS⁺) cells and endothelial progenitor cells. Furthermore, HMGB1 accelerated angiogenesis during DO, promoted the migration and osteogenic differentiation of hMSCs as well as the proliferation, migration and angiogenesis of HUVECs in vitro.

CONCLUSIONS

Our findings suggest that HMGB1 has a positive influence on endogenous stem/progenitor cells, representing a novel therapeutic target for the acceleration of DO-driven bone regeneration.

Innovations in the Treatment of Dystrophic Epidermolysis Bullosa (DEB): Current Landscape and Prospects

Dystrophic epidermolysis bullosa (DEB) is one of the major types of EB, a rare hereditary group of trauma-induced blistering skin disorders. DEB is caused by inherited pathogenic variants in the COL7A1 gene, which encodes type VII collagen, the major component of anchoring fibrils which maintain adhesion between the outer epidermis and underlying dermis. DEB can be subclassified into dominant (DDEB) and recessive (RDEB) forms. Generally, DDEB has a milder phenotype, while RDEB patients often have more extensive blistering, chronic inflammation, skin fibrosis, and a propensity for squamous cell carcinoma development, collectively impacting on daily activities and life expectancy. At present, best practice treatments are mostly supportive, and thus there is a considerable burden of disease with unmet therapeutic need. Over the last 20 years, considerable translational research efforts have focused on either trying to cure DEB by direct correction of the COL7A1 gene pathology, or by modifying secondary inflammation to lessen phenotypic severity and improve patient symptoms such as poor wound healing, itch, and pain. In this review, we provide an overview and update on various therapeutic innovations for DEB, including gene therapy, cell-based therapy, protein therapy, and disease-modifying and symptomatic control agents. We outline the progress and challenges for each treatment modality and identify likely prospects for future clinical impact.

High-mobility group box-1 peptide ameliorates bronchopulmonary dysplasia by suppressing inflammation and fibrosis in a mouse model

BACKGROUND

This study aimed to examine the effect of the HMGB1 peptide on Bronchopulmonary dysplasia (BPD)-related lung injury in a mouse model.

RESULTS

HMGB1 peptide ameliorates lung injury by suppressing the release of inflammatory cytokines and decreasing soluble collagen levels in the lungs. Single-cell RNA sequencing showed that the peptide suppressed the hyperoxia-induced inflammatory signature in macrophages and the fibrotic signature in fibroblasts. These changes in the transcriptome were confirmed using protein assays.

CONCLUSION

Systemic administration of HMGB1 peptide exerts anti-inflammatory and anti-fibrotic effects in a mouse model of BPD. This study provides a foundation for the development of new and effective therapies for BPD.

Post-myocardial infarction fibrosis: Pathophysiology, examination, and intervention

Cardiac fibrosis plays an indispensable role in cardiac tissue homeostasis and repair after myocardial infarction (MI). The cardiac fibroblast-to-myofibroblast differentiation and extracellular matrix collagen deposition are the hallmarks of cardiac fibrosis, which are modulated by multiple signaling pathways and various types of cells in time-dependent manners. Our understanding of the development of cardiac fibrosis after MI has evolved in basic and clinical researches, and the regulation of fibrotic remodeling may facilitate novel diagnostic and therapeutic strategies, and finally improve outcomes. Here, we aim to elaborate pathophysiology, examination and intervention of cardiac fibrosis after MI.

Peptide mediated therapy in fibrosis: Mechanisms, advances and prospects

Fibrosis, a disease characterized by an excess accumulation of extracellular matrix components, could lead to organ failure and death, and is to blame for up to 45 % of all fatalities in developed nations. These disorders all share the common trait of an unchecked and increasing accumulation of fibrotic tissue in the affected organs, which leads to their malfunction and eventual failure, even if their underlying causes are highly diverse and, in some cases, remain unclear. Numerous studies have identified activated myofibroblasts as the common cellular elements ultimately responsible for the replacement of normal tissues with nonfunctional fibrotic tissue. The transforming growth factor-β pathway, for instance, plays a significant role in practically all kinds of fibrosis. However, there is no specific drug for the treatment of fibrosis, several medications with anti-hepatic fibrosis properties are still in the research and development stages. Peptide, which refers to a substance consisting of 2-50 amino acids, is characterized by structural diversity, low toxicity, biological activities, easy absorption, specific targeting, few side effects, and has been proven to be effective in anti-fibrosis. Here, we summarized various anti-fibrosis peptides in fibrosis including the liver, lungs, kidneys, and other organs. This review will provide a new insight into peptide mediated anti-fibrosis and is helpful to creation of antifibrotic medications.

Synthesized HMGB1 peptide prevents the progression of inflammation, steatosis, fibrosis, and tumor occurrence in a non-alcoholic steatohepatitis mouse model

AIM

Non-alcoholic steatohepatitis (NASH) with fibrosis eventually leads to cirrhosis and hepatocellular carcinoma. Thus, the development of therapies other than dietary restriction and exercise, particularly those that suppress steatosis and fibrosis of the liver and have a long-term beneficial effect, is necessary. We aimed to evaluate the therapeutic effects of the HMGB1 peptide synthesized from box A using the melanocortin-4 receptor-deficient (Mc4r-KO) NASH model mouse.

METHODS

We performed short- and long-term administration of this peptide and evaluated the effects on steatosis, fibrosis, and carcinogenesis using Mc4r-KO mice. We also analyzed the direct effect of this peptide on macrophages and hepatic stellate cells in vitro and performed lipidomics and metabolomics techniques to evaluate the effect.

RESULTS

Although this peptide did not show direct effects on macrophages and hepatic stellate cells in vitro, in the short-term administration model, we could confirm the reduction of liver damage, steatosis, and fibrosis progression. The results of lipidomics and metabolomics suggested that the peptide might ameliorate NASH by promoting lipolysis via the activation of fatty acid β-oxidation and improving insulin resistance. In the long-term administration model, this peptide prevented progression to cirrhosis but retained the steatosis state, that is, the peptide prevents the progression to "burnt-out NASH." This peptide inhibited carcinogenesis by about one-third.

CONCLUSION

This HMGB1 peptide can reduce liver damage, improve fibrosis and steatosis, and inhibit carcinogenesis, suggesting that the peptide would be a new treatment candidate for NASH and can contribute to the long-term prognosis for patients with NASH.

Intravenous infusion of bone marrow-derived mesenchymal stem cells improves tissue perfusion in a rat hindlimb ischemia model

Intravenous infusion of stem cells is a minimally invasive cellular delivery method, though a few have been reported in a critical limb-threatening ischemia (CLTI) animal model or patients. In the present study, we hypothesized that intravenous infusion of bone-marrow derived mesenchymal stem cells (MSCs) improves tissue perfusion in a rat hindlimb ischemia model. Hindlimb ischemia was generated in Sprague-Dawley rats by femoral artery removal, then seven days after ischemic induction intravenous infusion of 1 × 10⁶ MSCs (cell group) or vehicle (control group) was performed. As compared with the control, tissue perfusion was significantly increased in the cell group. Histological findings showed that capillary density was significantly increased in the cell group, with infused green fluorescent protein (GFP)-MSCs distributed in the ischemic limb. Furthermore, gene expression of vascular endothelial growth factor (VEGF) was significantly increased in ischemic hindlimb muscle tissues of rats treated with MSC infusion. In conclusion, intravenous infusion of bone-marrow derived MSCs improved tissue perfusion in ischemic hindlimbs through angiogenesis, suggesting that intravenous infusion of MSCs was a promising cell delivery method for treatment of CLTI.

HMGB1-Mediated Activation of the Inflammatory-Reparative Response Following Myocardial Infarction

Different cell types belonging to the innate and adaptive immune system play mutually non-exclusive roles during the different phases of the inflammatory-reparative response that occurs following myocardial infarction. A timely and finely regulation of their action is fundamental for the process to properly proceed. The high-mobility group box 1 (HMGB1), a highly conserved nuclear protein that in the extracellular space can act as a damage-associated molecular pattern (DAMP) involved in a large variety of different processes, such as inflammation, migration, invasion, proliferation, differentiation, and tissue regeneration, has recently emerged as a possible regulator of the activity of different immune cell types in the distinct phases of the inflammatory reparative process. Moreover, by activating endogenous stem cells, inducing endothelial cells, and by modulating cardiac fibroblast activity, HMGB1 could represent a master regulator of the inflammatory and reparative responses following MI. In this review, we will provide an overview of cellular effectors involved in these processes and how HMGB1 intervenes in regulating each of them. Moreover, we will summarize HMGB1 roles in regulating other cell types that are involved in the different phases of the inflammatory-reparative response, discussing how its redox status could affect its activity.

Current topics in Epidermolysis bullosa: Pathophysiology and therapeutic challenges

Epidermolysis bullosa (EB) is a group of inherited skin and mucosal fragility disorders resulting from mutations in genes encoding basement membrane zone (BMZ) components or proteins that maintain the integrity of BMZ and adjacent keratinocytes. More than 30 years have passed since the first causative gene for EB was identified, and over 40 genes are now known to be responsible for the protean collection of mechanobullous diseases included under the umbrella term of EB. Through the elucidation of disease mechanisms using human skin samples, animal models, and cultured cells, we have now reached the stage of developing more effective therapeutics for EB. This review will initially focus on what is known about blister wound healing in EB, since recent and emerging basic science data are very relevant to clinical translation and therapeutic strategies for patients. We then place these studies in the context of the latest information on gene therapy, read-through therapy, and cell therapy that provide optimism for improved clinical management of people living with EB.

Investigational Treatments for Epidermolysis Bullosa

Epidermolysis bullosa (EB) is a heterogeneous group of rare inherited blistering skin disorders characterized by skin fragility following minor trauma, usually present since birth. EB can be categorized into four classical subtypes, EB simplex, junctional EB, dystrophic EB and Kindler EB, distinguished on clinical features, plane of blister formation in the skin, and molecular pathology. Treatment for EB is mostly supportive, focusing on wound care and patient symptoms such as itch or pain. However, therapeutic advances have also been made in targeting the primary genetic abnormalities as well as the secondary inflammatory footprint of EB. Pre-clinical or clinical testing of gene therapies (gene replacement, gene editing, RNA-based therapy, natural gene therapy), cell-based therapies (fibroblasts, bone marrow transplantation, mesenchymal stromal cells, induced pluripotential stem cells), recombinant protein therapies, and small molecule and drug repurposing approaches, have generated new hope for better patient care. In this article, we review advances in translational research that are impacting on the quality of life for people living with different forms of EB and which offer hope for improved clinical management.

Influence of Dipeptidyl Peptidase-4 (DPP4) on Mesenchymal Stem-Cell (MSC) Biology: Implications for Regenerative Medicine - Review

Dipeptidyl peptidase IV (DPP4) is a ubiquitous protease that can be found in membrane-anchored or soluble form. Incretins are one of the main DPP4 substrates. These hormones regulate glucose levels, by stimulating insulin secretion and decreasing glucagon production. Because DPP4 levels are high in diabetes, DPP4 inhibitor (DPP4i) drugs derived from gliptin are widespread used as hypoglycemic agents for its treatment. However, as DPP4 recognizes other substrates such as chemokines, growth factors and neuropeptides, pleiotropic effects have been observed in patients treated with DPP4i. Several of these substrates are part of the stem-cell niche. Thus, they may affect different physiological aspects of mesenchymal stem-cells (MSC). They include viability, differentiation, mobilization and immune response. MSC are involved in tissue homeostasis and regeneration under both physiological and pathological conditions. Therefore, such cells and their secretomes have a high clinical potential in regenerative medicine. In this context, DPP4 activity may modulate different aspects of MSC regenerative capacity. Therefore, the aim of this review is to analyze the effect of different DPP4 substrates on MSC. Likewise, how the regulation of DPP4 activity by DPP4i can be applied in regenerative medicine. That includes treatment of cardiovascular and bone pathologies, cutaneous ulcers, organ transplantation and pancreatic beta-cell regeneration, among others. Thus, DPP4i has an important clinical potential as a complement to therapeutic strategies in regenerative medicine. They involve enhancing the differentiation, immunomodulation and mobilization capacity of MSC for regenerative purposes.

Synthesized HMGB1 peptide attenuates liver inflammation and suppresses fibrosis in mice

The liver has a high regenerative ability and can induce spontaneous regression of fibrosis when early liver damage occurs; however, these abilities are lost when chronic liver damage results in decompensated cirrhosis. Cell therapies, such as mesenchymal stem cell (MSC) and macrophage therapies, have attracted attention as potential strategies for mitigating liver fibrosis. Here, we evaluated the therapeutic effects of HMGB1 peptide synthesized from box A of high mobility group box 1 protein. Liver damage and fibrosis were evaluated using a carbon tetrachloride (CCl4)-induced cirrhosis mouse model. The effects of HMGB1 peptide against immune cells were evaluated by single-cell RNA-seq using liver tissues, and those against monocytes/macrophages were further evaluated by in vitro analyses. Administration of HMGB1 peptide did not elicit a rapid response within 36 h, but attenuated liver damage after 1 week and suppressed fibrosis after 2 weeks. Fibrosis regression developed over time, despite continuous liver damage, suggesting that administration of this peptide could induce fibrolysis. In vitro analyses could not confirm a direct effect of HMGB1 peptide against monocyte/macrophages. However, macrophages were the most affected immune cells in the liver, and the number of scar-associated macrophages (Trem2+Cd9+ cells) with anti-inflammatory markers increased in the liver following HMGB1 treatment, suggesting that indirect effects of monocytes/macrophages were important for therapeutic efficacy. Overall, we established a new concept for cell-free therapy using HMGB1 peptide for cirrhosis through the induction of anti-inflammatory macrophages.