Noninvasive Monitoring of Palmitoyl Hexapeptide-12 in Human Skin Layers: Mechanical Interaction with Skin Components and Its Potential Skincare Benefits

Self-assembling peptides (SAPs) represent a rich source of building blocks that interact with biological structures. For instance, cosmetic SAPs like Palmitoyl hexapeptide-12 have gained increasing interest for their anti-aging properties. However, their short-term impact on the skin composition and mechanics remains unclear. In this study, a battery of label-free techniques is exploited to objectively monitor the effects of Palmitoyl hexapeptide-12 on human skin. Orbital trapping secondary ion mass spectrometry (OrbiSIMS) is used to discern between Palmitoyl hexapeptide-12 sol and gel forms, tracking its self-assembly and penetration within full-thickness human skin. Palmitoyl hexapeptide-12 is shown to permeate both stratum corneum and epidermal layers, initiating gel formation by harnessing endogenous ions. Hence, the ability of the peptide to strengthen and repair the skin barrier after delipidation is also demonstrated through a high-throughput mechanical characterization and stimulated Raman scattering (SRS). Finally, the co-assembling properties of Palmitoyl hexapeptide-12 with native skin molecules are shown via in vitro tests and ex vivo histology. This study establishes a methodological benchmark for measuring the effects of cosmetic peptides on skin mechanics and hydration, introducing a platform to design SAPs capable of harnessing native skin molecules to create "biocooperative" structures with cosmetic benefits.

Taohong siwu decoction suppresses oxidative stress-induced myocardial apoptosis post-myocardial infarction by inhibiting PTEN pathway

BACKGROUND

Myocardial infarction (MI) is an important factor inducing mortality globally. Apoptosis and oxidative stress have been identified as major drivers for MI development. Anti-apoptosis therapies exhibit promising effects in protecting against MI. Typically, Taohong Siwu Decoction (THSWD) exerts cardioprotective properties. However, whether THSWD suppresses oxidative stress-induced myocardial apoptosis after MI and the associated mechanisms remain unclear.

PURPOSE

The present work focused on examining the protective effects of THSWD on oxidative stress-induced myocardial apoptosis after MI and its possible mechanisms.

METHODS

The MI mouse model was established via left anterior descending coronary artery (LAD) ligation. Thereafter, echocardiography and histopathology were performed to examine the cardioprotective effects of THSWD. Meanwhile, the protective potential of THSWD against myocardial apoptosis and oxidative stress, as well as modulation of phosphatase and tensin homolog (PTEN) pathway in MI were investigated through TUNEL staining, ROS analysis, immunohistochemistry (IHC), Western blot (WB) and oxidative stress-related biochemical enzyme assay, respectively. Further, the apoptosis of neonatal cardiomyocytes (NCMs) and H9C2 cells was induced by TBHP in vitro. Thereafter, the impacts of THSWD on the TBHP-induced H9C2 and NCMs were detected by Hoechst33342/PI fluorescent staining, WB, ROS analysis, and oxidative stress-related biochemical enzyme assay. In addition, PTEN was overexpressed using transfection viruses in vivo and in vitro for further investigation.

RESULTS

THSWD might inhibit PTEN and promote the PI3K/AKT pathway in MI mice to prevent myocardial apoptosis. In vitro, THSWD prevented the TBHP-induced apoptosis of NCMs and H9C2 cells. This was achieved by blocking PTEN activity and regulating PI3K/AKT pathway. Moreover, PTEN overexpression significantly enhanced the TBHP-induced H9C2 apoptosis and oxidative stress-induced myocardial apoptosis after MI, and partially blocked the protection of THSWD against myocardial apoptosis and modulating PI3K/AKT pathway in vitro and in vivo.

CONCLUSION

THSWD suppressed oxidative stress-induced myocardial apoptosis in vitro and in vivo by inhibiting PTEN pathway.

Pretreatment with Notoginsenoside R1 enhances the efficacy of neonatal rat mesenchymal stem cell transplantation in model of myocardial infarction through regulating PI3K/Akt/FoxO1 signaling pathways

BACKGROUND

Although stem cell transplantation is a promising approach for the treatment of myocardial infarction (MI), there are still some problems faced such as the low survival rate of stem cells. Here, we investigated the role of Notoginsenoside R1 (NGR1) pretreatment in improving the effects of neonatal rat bone marrow mesenchymal stem cell (MSC) transplantation for treatment of MI.

METHODS

Cardiac functions were detected by echocardiography and the myocardial infarct size was determined by Masson's trichrome staining in a rat model of MI. The cardioprotective effects of NGR1/LY294002 co-pretreated MSCs was evaluated to explore the underlying mechanism. The angiogenesis was determined by vWF and α-SMA immunofluorescence staining and cell apoptosis was detected by TUNEL. In vitro, the effects of NGR1 on stem cell proliferation was examined by CCK-8 and levels of P-Akt, P-CREB, P-FoxO1 were detected by western blot. Apoptosis, ROS content, and cytokine levels were examined by DAPI and TUNEL staining, a ROS assay kit, and ELISA, respectively.

RESULTS

NGR1 elevated the therapeutic effect of MSC transplantation on infarction by preserving cardiac function, increasing angiogenesis and expressions of IGF-1, VEGF, and SDF-1, and reducing cell apoptosis, whereas the addition of LY294002 prior to NGR1 treatment significantly counteracted the foregoing effects of NGR1. NGR1 pretreatment and SC79 pretreatment were similar in that both significantly increased P-Akt and P-FoxO1 levels in MSC and did not affect P-CREB levels. Besides, both NGR1 and SC79 promoted VEGF, SCF and bFGF levels in MSC cultures, and significantly reduced ROS accumulation and the attenuated cell apoptosis in MSC triggered by H2O2. Similarly, addition of LY294002 before NGR1 treatment significantly counteracted the aforementioned effects of NGR1 in vitro.

CONCLUSIONS

NGR1 pretreatment enhances the effect of MSC transplantation for treatment of MI through paracrine signaling, and the mechanism underlying this effect may be associated with PI3K/Akt/FoxO1 signaling pathways.

Genetically modified mesenchymal stromal cells: a cell-based therapy offering more efficient repair after myocardial infarction

Myocardial infarction (MI) is a serious complication of coronary artery disease. This condition is common worldwide and has a profound impact on patients' lives and quality of life. Despite significant advances in the treatment of heart disease in modern medicine, the efficient treatment of MI still faces a number of challenges. Problems such as scar formation and loss of myocardial function after a heart attack still limit patients' recovery. Therefore, the search for a new therapeutic tool that can promote repair and regeneration of myocardial tissue has become crucial. In this context, mesenchymal stromal cells (MSCs) have attracted much attention as a potential therapeutic tool. MSCs are a class of adult stem cells with multidirectional differentiation potential, derived from bone marrow, fat, placenta and other tissues, and possessing properties such as self-renewal and immunomodulation. The application of MSCs may provide a new direction for the treatment of MI. These stem cells have the potential to differentiate into cardiomyocytes and vascular endothelial cells in damaged tissue and to repair and protect myocardial tissue through anti-inflammatory, anti-fibrotic and pro-neovascularization mechanisms. However, the clinical results of MSCs transplantation for the treatment of MI are less satisfactory due to the limitations of the native function of MSCs. Genetic modification has overcome problems such as the low survival rate of transplanted MSCs in vivo and enhanced their functions of promoting neovascularization and differentiation into cardiomyocytes, paving the way for them to become an effective tool for repair therapy after MI. In previous studies, MSCs have shown some therapeutic potential in experimental animals and preliminary clinical trials. This review aims to provide readers with a comprehensive and in-depth understanding to promote the wider application of engineering MSCs in the field of MI therapy, offering new hope for recovery and improved survival of cardiac patients.

The therapeutic efficacy and clinical translation of mesenchymal stem cell-derived exosomes in cardiovascular diseases

Exosomes, mainly derived from mesenchymal stem cells, provide a good reference for cardiac function repair and clinical application in cardiac and vascular diseases by regulating cardiomyocyte viability, inflammatory levels, angiogenesis, and ventricular remodeling after a heart injury. This review presents the cardioprotective efficacy of mesenchymal stem cell-originated exosomes and explores the underlying molecular mechanisms. Furthermore, we expound on several efficient approaches to transporting exosomes into the heart in clinical application and comment on the advantages and disadvantages of each method.

Self-assembling peptide RADA16: a promising scaffold for tissue engineering and regenerative medicine

RADA16 is a peptide-based biomaterial whose acidic aqueous solution spontaneously forms an extracellular matrix-like 3D structure within seconds upon contact with physiological pH body fluids. Meanwhile, its good biocompatibility, low immunogenicity, nontoxic degradation products and ease of modification make it an ideal scaffold for tissue engineering. RADA16 is a good delivery vehicle for cells, drugs and factors. Its shear thinning and thixotropic properties allow it to fill tissue voids by injection and not to swell. However, the weaker mechanical properties and poor hydrophilicity are troubling limitations of RADA16. To compensate for this limitation, various functional groups and polymers have been designed to modify RADA16, thus contributing to its scope and progress in the field of tissue engineering.

Synthetic extracellular matrices with function-encoding peptides

The communication of cells with their surroundings is mostly encoded in the epitopes of structural and signalling proteins present in the extracellular matrix (ECM). These peptide epitopes can be incorporated in biomaterials to serve as function-encoding molecules to modulate cell-cell and cell-ECM interactions. In this Review, we discuss natural and synthetic peptide epitopes as molecular tools to bioengineer bioactive hydrogel materials. We present a library of functional peptide sequences that selectively communicate with cells and the ECM to coordinate biological processes, including epitopes that directly signal to cells, that bind ECM components that subsequently signal to cells, and that regulate ECM turnover. We highlight how these epitopes can be incorporated in different biomaterials as individual or multiple signals, working synergistically or additively. This molecular toolbox can be applied in the design of biomaterials aimed at regulating or controlling cellular and tissue function, repair and regeneration.

Design of Recombinant Spider Silk Proteins for Cell Type Specific Binding

Cytophilic (cell-adhesive) materials are very important for tissue engineering and regenerative medicine. However, for engineering hierarchically organized tissue structures comprising different cell types, cell-specific attachment and guidance are decisive. In this context, materials made of recombinant spider silk proteins are promising scaffolds, since they exhibit high biocompatibility, biodegradability, and the underlying proteins can be genetically functionalized. Here, previously established spider silk variants based on the engineered Araneus diadematus fibroin 4 (eADF4(C16)) are genetically modified with cell adhesive peptide sequences from extracellular matrix proteins, including IKVAV, YIGSR, QHREDGS, and KGD. Interestingly, eADF4(C16)-KGD as one of 18 tested variants is cell-selective for C2C12 mouse myoblasts, one out of 11 tested cell lines. Co-culturing with B50 rat neuronal cells confirms the cell-specificity of eADF4(C16)-KGD material surfaces for C2C12 mouse myoblast adhesion.

Mesenchymal Stem Cells and Their Exocytotic Vesicles

Mesenchymal stem cells (MSCs), as a kind of pluripotent stem cells, have attracted much attention in orthopedic diseases, geriatric diseases, metabolic diseases, and sports functions due to their osteogenic potential, chondrogenic differentiation ability, and adipocyte differentiation. Anti-inflammation, anti-fibrosis, angiogenesis promotion, neurogenesis, immune regulation, and secreted growth factors, proteases, hormones, cytokines, and chemokines of MSCs have been widely studied in liver and kidney diseases, cardiovascular and cerebrovascular diseases. In recent years, many studies have shown that the extracellular vesicles of MSCs have similar functions to MSCs transplantation in all the above aspects. Here we review the research progress of MSCs and their exocrine vesicles in recent years.

Calycosin protects against oxidative stress-induced cardiomyocyte apoptosis by activating aldehyde dehydrogenase 2

Myocardial infarction (MI) is the leading cause of death worldwide, and oxidative stress is part of the process that causes MI. Calycosin, a naturally occurring substance with cardioprotective properties, is one of the major active constituents in Radix Astragali. In this study, effect of Calycosin was investigated in vivo and in vitro to determine whether it could alleviate oxidative stress and oxidative stress-induced cardiac apoptosis in neonatal cardiomyocytes (NCMs) via activation of aldehyde dehydrogenase 2 (ALDH2). Calycosin protected against oxidative stress and oxidative stress-induced apoptosis in NCMs. Molecular docking revealed that the ALDH2-Calycosin complex had a binding energy of -9.885 kcal/mol. In addition, molecular docking simulations demonstrated that the ALDH2-Calycosin complex was stable. Using BLI assays, we confirmed that Calycosin could interact with ALDH2 (K_D  = 1.9 × 10^-4  M). Furthermore, an ALDH2 kinase activity test revealed that Calycosin increased ALDH2 activity, exhibiting an EC50 of 91.79 μM. Pre-incubation with ALDH2 inhibitor (CVT-10216 or disulfiram) reduced the cardio-protective properties Calycosin. In mice with MI, Calycosin therapy substantially reduced myocardial apoptosis, oxidative stress, and activated ALDH2. Collectively, our findings clearly suggest that Calycosin reduces oxidative stress and oxidative stress-induced apoptosis via the regulation of ALDH2 signaling, which supports potential therapeutic use in MI.

Paracrine Factors Released by Stem Cells of Mesenchymal Origin and their Effects in Cardiovascular Disease: A Systematic Review of Pre-clinical Studies

Mesenchymal stem cell (MSC) therapy has gained significant traction in the context of cardiovascular repair, and have been proposed to exert their regenerative effects via the secretion of paracrine factors. In this systematic review, we examined the literature and consolidated available evidence for the "paracrine hypothesis". Two Ovid SP databases were searched using a strategy encompassing paracrine mediated MSC therapy in the context of ischemic heart disease. This yielded 86 articles which met the selection criteria for inclusion in this study. We found that the MSCs utilized in these articles were primarily derived from bone marrow, cardiac tissue, and adipose tissue. We identified 234 individual protective factors across these studies, including VEGF, HGF, and FGF2; which are proposed to exert their effects in a paracrine manner. The data collated in this systematic review identifies secreted paracrine factors that could decrease apoptosis, and increase angiogenesis, cell proliferation, and cell viability. These included studies have also demonstrated that the administration of MSCs and indirectly, their secreted factors can reduce infarct size, and improve left ventricular ejection fraction, contractility, compliance, and vessel density. Furthering our understanding of the way these factors mediate repair could lead to the identification of therapeutic targets for cardiac regeneration.

Modification Strategies for Ionic Complementary Self-Assembling Peptides: Taking RADA16-I as an Example

Ion-complementary self-assembling peptides have been studied in many fields for their distinct advantages, mainly due to their self-assembly properties. However, their shortcomings, such as insufficient specific activity and poor mechanical properties, also limited their application. For the better and wider application of these promising biomaterials, ion-complementary self-assembling peptides can be modified with their self-assembly properties not being destroyed to the greatest extent. The modification strategies were reviewed by taking RADA16-I as an example. For insufficient specific activity, RADA16-I can be structurally modified with active motifs derived from the active domain of the extracellular matrix or other related active factors. For weak mechanical properties, materials with strong mechanical properties or that can undergo chemical crosslinking were used to mix with RADA16-I to enhance the mechanical properties of RADA16-I. To improve the performance of RADA16-I as drug carriers, appropriate adjustment of the RADA16-I sequence and/or modification of the RADA16-I-related delivery system with polymer materials or specific molecules can be considered to achieve sustained and controlled release of specific drugs or active factors. The modification strategies reviewed in this paper may provide some references for further basic research and clinical application of ion-complementary self-assembling peptides and their derivatives.

Effectiveness of exosome mediated miR-126 and miR-146a delivery on cardiac tissue regeneration

Despite advances in the treatment of acute myocardial infarction, due to the non-proliferative nature of adult cardiomyocytes, the injured myocardium is mainly replaced by fibrotic tissue, which ultimately causes heart failure. To prevent heart failure, particularly after myocardial infarction, exosome-based therapy has emerged as one of the most promising strategies to regenerate cardiac function. Exosomes can carry microRNAs in support of neovascularization, anti-inflammatory, and endogenous cardiac regeneration. This study demonstrated that animal rat models' combination treatment with microRNA-126 and microRNA-146a mimics in exosomes is desirable for cardiac regeneration after myocardial infarction. The exosomes isolated from stem cells and loaded with microRNAs were characterized their impacts in cell migration, tube formation, and vascular endothelial growth factor degree. In the following, the usefulness of loaded microRNAs in exosomes and their encapsulation within alginate derivative hydrogel was analyzed in myocardial infarction for an animal model. Exosomes isolated and loaded with microRNAs showed the synergetic impact on cell migration, tube formation, and promoted vascular endothelial growth factor folding. Moreover, microRNAs loaded exosomes and encapsulated them in alginate hydrogel could help in reducing infarct size and improving angiogenesis in myocardial infarction. The angiogenesis markers including CD31 and connexion 43 upregulated for myocardial infarction models treated with alginate-based hydrogels loaded with exosomes and microRNAs-exosomes. Histological analysis indicated that myocardial infarction model rats treated with alginate hydrogel loaded with microRNAs-exosomes possessed lower and higher degrees of fibrosis and collagen fiber, respectively. These findings have important therapeutic implications for a myocardial infarction model through angiogenesis and vascular integrity regulation.

Induction of Stem-Cell-Derived Cardiomyogenesis by Fibroblast Growth Factor 10 (FGF10) and Its Interplay with Cardiotrophin-1 (CT-1)

Simple Summary

Cardiovascular diseases are worldwide one of the leading contributors of mortality, and among multiple therapeutic approaches, stem cell therapy has been introduced as a robust therapeutic strategy to alleviate related symptoms and restore cardiac functions. Prior to this, however, for successful cell therapy, an adequate number of functional and safe cardiac cells needs to be generated. For this purpose, our approach was boosting the proliferative capacity of stem cell-derived cardiomyocytes using growth factors, such as fibroblast growth factor 10 (FGF10) and cardiotrophin-1 (CT-1). Our results demonstrated that FGF10 and CT-1 substantially increased the number of cardiac cells that originated from stem cells. In molecular assays, to assess RNA and protein level alterations, the enhanced presence of specific markers for cardiac cells after treatment of stem cells with FGF10 and/or CT-1 was confirmed. This inducing potential of cardiac cells can particularly be applicable in the cell replacement-based therapies of cardiac infarction. This research sheds light on the putative effect of FGF10 and CT-1 in the transition of stem cells to cardiac cells, leading to the repair and survival of the heart.

Abstract

For heart regeneration purposes, embryonic stem cell (ES)-based strategies have been developed to induce the proliferation of cardiac progenitor cells towards cardiomyocytes. Fibroblast growth factor 10 (FGF10) contributes to cardiac development and induces cardiomyocyte differentiation in vitro. Yet, among pro-cardiogenic factors, including cardiotrophin-1 (CT-1), the hyperplastic function of FGF10 in cardiomyocyte turnover remains to be further characterized. We investigated the proliferative effects of FGF10 on ES-derived cardiac progenitor cells in the intermediate developmental stage and examined the putative interplay between FGF10 and CT-1 in cardiomyocyte proliferation. Mouse ES cells were treated with FGF10 and/or CT-1. Differential expression of cardiomyocyte-specific gene markers was analyzed at transcript and protein levels. Substantial upregulation of sarcomeric α-actinin was detected by qPCR, flow cytometry, Western blot and immunocytochemistry. FGF10 enhanced the expression of other structural proteins (MLC-2a, MLC-2v and TNNT2), transcriptional factors (NKX2-5 and GATA4), and proliferation markers (Aurora B and YAP-1). FGF10/CT-1 co-administration led to an upregulation of proliferation markers, suggesting the synergistic potential of FGF10 + CT-1 on cardiomyogenesis. In summary, we provided evidence that FGF10 and CT-1 induce cardiomyocyte structural proteins, associated transcription factors, and cardiac cell proliferation, which could be applicable in therapies to replenish damaged cardiomyocytes.

Biomaterials via peptide assembly: Design, characterization, and application in tissue engineering

A core challenge in biomaterials, with both fundamental significance and technological relevance, concerns the rational design of bioactive microenvironments. Designed properly, peptides can undergo supramolecular assembly into dynamic, physical hydrogels that mimic the mechanical, topological, and biochemical features of native tissue microenvironments. The relatively facile, inexpensive, and automatable preparation of peptides, coupled with low batch-to-batch variability, motivates the expanded use of assembling peptide hydrogels for biomedical applications. Integral to realizing dynamic peptide assemblies as functional biomaterials for tissue engineering is an understanding of the molecular and macroscopic features that govern assembly, morphology, and biological interactions. In this review, we first discuss the design of assembling peptides, including primary structure (sequence), secondary structure (e.g., α-helix and β-sheets), and molecular interactions that facilitate assembly into multiscale materials with desired properties. Next, we describe characterization tools for elucidating molecular structure and interactions, morphology, bulk properties, and biological functionality. Understanding of these characterization methods enables researchers to access a variety of approaches in this ever-expanding field. Finally, we discuss the biological properties and applications of peptide-based biomaterials for engineering several important tissues. By connecting molecular features and mechanisms of assembling peptides to the material and biological properties, we aim to guide the design and characterization of peptide-based biomaterials for tissue engineering and regenerative medicine. STATEMENT OF SIGNIFICANCE: Engineering peptide-based biomaterials that mimic the topological and mechanical properties of natural extracellular matrices provide excellent opportunities to direct cell behavior for regenerative medicine and tissue engineering. Here we review the molecular-scale features of assembling peptides that result in biomaterials that exhibit a variety of relevant extracellular matrix-mimetic properties and promote beneficial cell-biomaterial interactions. Aiming to inspire and guide researchers approaching this challenge from both the peptide biomaterial design and tissue engineering perspectives, we also present characterization tools for understanding the connection between peptide structure and properties and highlight the use of peptide-based biomaterials in neural, orthopedic, cardiac, muscular, and immune engineering applications.

A deep dive into the darning effects of biomaterials in infarct myocardium: current advances and future perspectives

Myocardial infarction (MI) occurs due to the obstruction of coronary arteries, a major crux that restricts blood flow and thereby oxygen to the distal part of the myocardium, leading to loss of cardiomyocytes and eventually, if left untreated, leads to heart failure. MI, a potent cardiovascular disorder, requires intense therapeutic interventions and thereby presents towering challenges. Despite the concerted efforts, the treatment strategies for MI are still demanding, which has paved the way for the genesis of biomaterial applications. Biomaterials exhibit immense potentials for cardiac repair and regeneration, wherein they act as extracellular matrix replacing scaffolds or as delivery vehicles for stem cells, protein, plasmids, etc. This review concentrates on natural, synthetic, and hybrid biomaterials; their function; and interaction with the body, mechanisms of repair by which they are able to improve cardiac function in a MI milieu. We also provide focus on future perspectives that need attention. The cognizance provided by the research results certainly indicates that biomaterials could revolutionize the treatment paradigms for MI with a positive impact on clinical translation.

Synthetic scaffolds for 3D cell cultures and organoids: applications in regenerative medicine

Three-dimensional (3D) cell cultures offer an unparalleled platform to recreate spatial arrangements of cells in vitro. 3D cell culture systems have gained increasing interest due to their evident advantages in providing more physiologically relevant information and more predictive data compared to their two-dimensional (2D) counterpart. Design and well-established fabrication of organoids (a particular type of 3D cell culture system) are nowadays considered a pivotal achievement for their ability to replicate in vitro cytoarchitecture and the functionalities of an organ. In this condition, pluripotent stem cells self-organize into 3D structures mimicking the in vivo microenvironments, architectures and multi-lineage differentiation. Scaffolds are key supporting elements in these 3D constructs, and Matrigel is the most commonly used matrix despite its relevant translation limitations including animal-derived sources, non-defined composition, batch-to-batch variability and poorly tailorable properties. Alternatively, 3D synthetic scaffolds, including self-assembling peptides, show promising biocompatibility and biomimetic properties, and can be tailored on specific target tissue/cells. In this review, we discuss the recent advances on 3D cell culture systems and organoids, promising tools for tissue engineering and regenerative medicine applications. For this purpose, we will describe the current state-of-the-art on 3D cell culture systems and organoids based on currently available synthetic-based biomaterials (including tailored self-assembling peptides) either tested in in vivo animal models or developed in vitro with potential application in the field of tissue engineering, with the aim to inspire researchers to take on such promising platforms for clinical applications in the near future.

Stem cell-seeded 3D-printed scaffolds combined with self-assembling peptides for bone defect repair

Bone defects caused by infection, tumor, trauma and so on remain difficult to treat clinically. Bone tissue engineering (BTE) has great application prospect in promoting bone defect repair. Polycaprolactone (PCL) is a commonly used material for creating BTE scaffolds. In addition, self-assembling peptides (SAPs) can function as the extracellular matrix and promote osteogenesis and angiogenesis. In the work, a PCL scaffold was constructed by 3D printing, then integrated with bone marrow mesenchymal stem cells (BMSCs) and SAPs. The research aimed to assess the bone repair ability of PCL/BMSC/SAP implants. BMSC proliferation in PCL/SAP scaffolds was assessed via Cell Counting Kit-8. In vitro osteogenesis of BMSCs cultured in PCL/SAP scaffolds was assessed by alkaline phosphatase staining and activity assays. Enzyme linked immunosorbent assays were also performed to detect the levels of osteogenic factors. The effects of BMSC-conditioned medium from 3D culture systems on the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) were assessed by scratch, transwell, and tube formation assays. After 8 weeks of in vivo transplantation, radiography and histology were used to evaluate bone regeneration, and immunohistochemistry staining was utilized to detect neovascularization. In vitro results demonstrated that PCL/SAP scaffolds promoted BMSC proliferation and osteogenesis compared to PCL scaffolds, and the PCL/BMSC/SAP conditional medium (CM) enhanced HUVEC migration and angiogenesis compared to the PCL/BMSC CM. In vivo results showed that, compared to the blank control, PCL, and PCL/BMSC groups, the PCL/BMSC/SAP group had significantly increased bone and blood vessel formation. Thus, the combination of BMSC-seeded 3D-printed PCL and SAPs can be an effective approach for treating bone defects.

Biologics and their delivery systems: Trends in myocardial infarction

Cardiovascular disease is the leading cause of death around the world, in which myocardial infarction (MI) is a precipitating event. However, current therapies do not adequately address the multiple dysregulated systems following MI. Consequently, recent studies have developed novel biologic delivery systems to more effectively address these maladies. This review utilizes a scientometric summary of the recent literature to identify trends among biologic delivery systems designed to treat MI. Emphasis is placed on sustained or targeted release of biologics (e.g. growth factors, nucleic acids, stem cells, chemokines) from common delivery systems (e.g. microparticles, nanocarriers, injectable hydrogels, implantable patches). We also evaluate biologic delivery system trends in the entire regenerative medicine field to identify emerging approaches that may translate to the treatment of MI. Future developments include immune system targeting through soluble factor or chemokine delivery, and the development of advanced delivery systems that facilitate the synergistic delivery of biologics.

Biomechanics of Wound Healing in an Equine Limb Model: Effect of Location and Treatment with a Peptide-Modified Collagen-Chitosan Hydrogel

The equine distal limb wound healing model, characterized by delayed re-epithelialization and a fibroproliferative response to wounding similar to that observed in humans, is a valuable tool for the study of biomaterials poised for translation into both the veterinary and human medical markets. In the current study, we developed a novel method of biaxial biomechanical testing to assess the functional outcomes of healed wounds in a modified equine model and discovered significant functional and structural differences in both unwounded and injured skin at different locations on the distal limb that must be considered when using this model in future work. Namely, the medial skin was thicker and displayed earlier collagen engagement, medial wounds experienced a greater proportion of wound contraction during closure, and proximal wounds produced significantly more exuberant granulation tissue. Using this new knowledge of the equine model of aberrant wound healing, we then investigated the effect of a peptide-modified collagen-chitosan hydrogel on wound healing. Here, we found that a single treatment with the QHREDGS (glutamine-histidine-arginine-glutamic acid-aspartic acid-glycine-serine) peptide-modified hydrogel (Q-peptide hydrogel) resulted in a higher rate of wound closure and was able to modulate the biomechanical function toward a more compliant healed tissue without observable negative effects. Thus, we conclude that the use of a Q-peptide hydrogel provides a safe and effective means of improving the rate and quality of wound healing in a large animal model.

Self-Assembling Peptide-Based Hydrogels in Angiogenesis

Ischemic diseases, especially in the heart and the brain, have become a serious threat to human health. Growth factor and cell therapy are emerging as promising therapeutic strategies; however, their retention and sustainable functions in the injured tissue are limited. Self-assembling peptide (SAP)-based hydrogels, mimicking the extracellular matrix, are therefore introduced to encapsulate and controllably release cells, cell-derived exosomes or growth factors, thus promoting angiogenesis and tissue recovery after ischemia. We will summarize the classification, composition and structure of SAPs, and the influencing factors for SAP gelation. Moreover, we will describe the functionalized SAPs, and the combinatorial therapy of cells, exosomes or growth factors with functionalized SAPs for angiogenic process as well as its advantage in immunogenicity and injectability. Finally, an outlook on future directions and challenges is provided.

Proteomic Analysis Reveals the Effect of Trichostatin A and Bone Marrow-Derived Dendritic Cells on the Fatty Acid Metabolism of NIH3T3 Cells under Oxygen-Glucose Deprivation Conditions

Fibroblasts mediate acute wound healing and long-term tissue remodeling with scarring after tissue injury. Following myocardial infarction (MI), necrotized cardiomyocytes become replaced by secreted extracellular matrix proteins produced by fibroblasts. Dendritic cells (DCs) can migrate from the bone marrow to the infarct areas and infarct border areas to mediate collagen accumulation after MI. Trichostatin A (TSA) is known to regulate apoptosis and proliferation in fibroblasts and affect the functions of DCs under oxygen-glucose deprivation (OGD) conditions. In this study, we used label-free quantitative proteomics to investigate the effects of TSA and bone marrow-derived dendritic cells (BMDCs) on NIH3T3 fibroblasts under OGD conditions. The results showed that the fatty acid degradation pathway was significantly upregulated in NIH3T3 cells under OGD conditions and that the fatty acid synthesis pathway was significantly downregulated in NIH3T3 cells treated with conditioned media (CM) from BMDCs treated with TSA under OGD conditions [BMDCs-CM(TSA)]. In addition, BMDCs-CM(TSA) significantly decreased the levels of triglycerides and free fatty acids and mediated fatty acid metabolism-related proteins in NIH3T3 cells under OGD conditions. In summary, this proteomics analysis showed that TSA and BMDCs affect fatty acid metabolism in NIH3T3 cells under OGD conditions.

Synthetic peptide hydrogels as 3D scaffolds for tissue engineering

The regeneration of tissues and organs poses an immense challenge due to the extreme complexity in the research work involved. Despite the tissue engineering approach being considered as a promising strategy for more than two decades, a key issue impeding its progress is the lack of ideal scaffold materials. Nature-inspired synthetic peptide hydrogels are inherently biocompatible, and its high resemblance to extracellular matrix makes peptide hydrogels suitable 3D scaffold materials. This review covers the important aspects of peptide hydrogels as 3D scaffolds, including mechanical properties, biodegradability and bioactivity, and the current approaches in creating matrices with optimized features. Many of these scaffolds contain peptide sequences that are widely reported for tissue repair and regeneration and these peptide sequences will also be discussed. Furthermore, 3D biofabrication strategies of synthetic peptide hydrogels and the recent advances of peptide hydrogels in tissue engineering will also be described to reflect the current trend in the field. In the final section, we will present the future outlook in the design and development of peptide-based hydrogels for translational tissue engineering applications.

Biomaterials Loaded with Growth Factors/Cytokines and Stem Cells for Cardiac Tissue Regeneration

Myocardial infarction causes cardiac tissue damage and the release of damage-associated molecular patterns leads to activation of the immune system, production of inflammatory mediators, and migration of various cells to the site of infarction. This complex response further aggravates tissue damage by generating oxidative stress, but it eventually heals the infarction site with the formation of fibrotic tissue and left ventricle remodeling. However, the limited self-renewal capability of cardiomyocytes cannot support sufficient cardiac tissue regeneration after extensive myocardial injury, thus, leading to an irreversible decline in heart function. Approaches to improve cardiac tissue regeneration include transplantation of stem cells and delivery of inflammation modulatory and wound healing factors. Nevertheless, the harsh environment at the site of infarction, which consists of, but is not limited to, oxidative stress, hypoxia, and deficiency of nutrients, is detrimental to stem cell survival and the bioactivity of the delivered factors. The use of biomaterials represents a unique and innovative approach for protecting the loaded factors from degradation, decreasing side effects by reducing the used dosage, and increasing the retention and survival rate of the loaded cells. Biomaterials with loaded stem cells and immunomodulating and tissue-regenerating factors can be used to ameliorate inflammation, improve angiogenesis, reduce fibrosis, and generate functional cardiac tissue. In this review, we discuss recent findings in the utilization of biomaterials to enhance cytokine/growth factor and stem cell therapy for cardiac tissue regeneration in small animals with myocardial infarction.

Designer Self-Assembling Peptide Hydrogels to Engineer 3D Cell Microenvironments for Cell Constructs Formation and Precise Oncology Remodeling in Ovarian Cancer

Designer self-assembling peptides form the entangled nanofiber networks in hydrogels by ionic-complementary self-assembly. This type of hydrogel has realistic biological and physiochemical properties to serve as biomimetic extracellular matrix (ECM) for biomedical applications. The advantages and benefits are distinct from natural hydrogels and other synthetic or semisynthetic hydrogels. Designer peptides provide diverse alternatives of main building blocks to form various functional nanostructures. The entangled nanofiber networks permit essential compositional complexity and heterogeneity of engineering cell microenvironments in comparison with other hydrogels, which may reconstruct the tumor microenvironments (TMEs) in 3D cell cultures and tissue-specific modeling in vitro. Either ovarian cancer progression or recurrence and relapse are involved in the multifaceted TMEs in addition to mesothelial cells, fibroblasts, endothelial cells, pericytes, immune cells, adipocytes, and the ECM. Based on the progress in common hydrogel products, this work focuses on the diverse designer self-assembling peptide hydrogels for instructive cell constructs in tissue-specific modeling and the precise oncology remodeling for ovarian cancer, which are issued by several research aspects in a 3D context. The advantages and significance of designer peptide hydrogels are discussed, and some common approaches and coming challenges are also addressed in current complex tumor diseases.

Mesenchymal stem cell-derived extracellular vesicles alone or in conjunction with a SDKP-conjugated self-assembling peptide improve a rat model of myocardial infarction

PURPOSE

The aim of this study was to investigate the cardiac repair effect of human bone marrow mesenchymal stromal cells-derived extracellular vesicles (MSC-EVs) after intramyocardial injection in free form or encapsulated within a self-assembling peptide hydrogel modified with SDKP motif, in a rat model of myocardial infarction (MI).

METHODS

MSC-EVs were isolated by ultracentrifuge and characterized for physical parameters and surface proteins. Furthermore, cellular uptake and cardioprotective effects of MSC-EVs were evaluated in vitro using neonatal mouse cardiomyocytes (NMCMs). In vivo effects of MSC-EVs on cardiac repair were studied in rat MI model by comparing the vehicle group (injected with PBS), EV group (injected with MSC-EVs) and Gel + EV group (injected with MSC-EVs encapsulated in (RADA)4-SDKP hydrogel) with respect to cardiac function and fibrotic area using echocardiography and Masson's trichrome staining, respectively. Histological sections were assessed by α-SMA and CD68 immunostaining to investigate the angiogenic and anti-inflammatory effects of the MSC-EVs.

RESULTS

We observed the uptake of MSC-EVs into NMCMs which led to NMCMs protection against H2O2-induced oxidative stress by substantial reduction of apoptosis. In myocardial infarcted rats, cardiac function was improved after myocardial injection of MSC-EVs alone or in conjunction with (RADA)4-SDKP hydrogel. This functional restoration coincided with promotion of angiogenesis and decrement of fibrosis and inflammation.

CONCLUSION

These data demonstrated that MSC-EVs can be used alone as a potent therapeutic agent for improvement of myocardial infarction.

Message in a Bottle: Upgrading Cardiac Repair into Rejuvenation

Ischaemic cardiac disease is associated with a loss of cardiomyocytes and an intrinsic lack of myocardial renewal. Recent work has shown that the heart retains limited cardiomyocyte proliferation, which remains inefficient when facing pathological conditions. While broadly active in the neonatal mammalian heart, this mechanism becomes quiescent soon after birth, suggesting loss of regenerative potential with maturation into adulthood. A key question is whether this temporary regenerative window can be enhanced via appropriate stimulation and further extended. Recently the search for novel therapeutic approaches for heart disease has centred on stem cell biology. The “paracrine effect” has been proposed as a promising strategy to boost endogenous reparative and regenerative mechanisms from within the cardiac tissue by exploiting the modulatory potential of soluble stem cell-secreted factors. As such, growing interest has been specifically addressed towards stem/progenitor cell-secreted extracellular vesicles (EVs), which can be easily isolated in vitro from cell-conditioned medium. This review will provide a comprehensive overview of the current paradigm on cardiac repair and regeneration, with a specific focus on the role and mechanism(s) of paracrine action of EVs from cardiac stromal progenitors as compared to exogenous stem cells in order to discuss the optimal choice for future therapy. In addition, the challenges to overcoming translational EV biology from bench to bedside for future cardiac regenerative medicine will be discussed.

A Cell-Free SDKP-Conjugated Self-Assembling Peptide Hydrogel Sufficient for Improvement of Myocardial Infarction

Biomaterials in conjunction with stem cell therapy have recently attracted attention as a new therapeutic approach for myocardial infarction (MI), with the aim to solve the delivery challenges that exist with transplanted cells. Self-assembling peptide (SAP) hydrogels comprise a promising class of synthetic biomaterials with cardiac-compatible properties such as mild gelation, injectability, rehealing ability, and potential for sequence modification. Herein, we developed an SAP hydrogel composed of a self-assembling gel-forming core sequence (RADA) modified with SDKP motif with pro-angiogenic and anti-fibrotic activity to be used as a cardioprotective scaffold. The RADA-SDKP hydrogel was intramyocardially injected into the infarct border zone of a rat model of MI induced by left anterior descending artery (LAD) ligation as a cell-free or a cell-delivering scaffold for bone marrow mesenchymal stem cells (BM-MSCs). The left ventricular ejection fraction (LVEF) was markedly improved after transplantation of either free hydrogel or cell-laden hydrogel. This cardiac functional repair coincided very well with substantially lower fibrotic tissue formation, expanded microvasculature, and lower inflammatory response in the infarct area. Interestingly, BM-MSCs alone or in combination with hydrogel could not surpass the cardiac repair effects of the SDKP-modified SAP hydrogel. Taken together, we suggest that the RADA-SDKP hydrogel can be a promising cell-free construct that has the capability for functional restoration in the instances of acute myocardial infarction (AMI) that might minimize the safety concerns of cardiac cell therapy and facilitate clinical extrapolation.

Taohong Siwu Decoction Exerts a Beneficial Effect on Cardiac Function by Possibly Improving the Microenvironment and Decreasing Mitochondrial Fission after Myocardial Infarction

Cardiovascular disease has been established as a major cause of morbidity and mortality worldwide, resulting in a huge burden to patients, families, and society. Traditional Chinese Medicine (TCM) presents several advantages for the prevention and treatment of cardiovascular diseases including multitargets, multi-ingredients, fewer side effects, and low cost. In this study, a rat model of myocardial infarction (MI) was established by ligating the anterior descending branch of the left coronary artery, and the effect of the Taohong Siwu decoction (THSWD) on cardiac function was evaluated in MI rats. Following the intragastric administration of THSWD, the cardiac function was examined using echocardiography. The infarct size and collagen deposition in the infarct area were measured using Masson's trichrome staining, and the number of CD31- and α-SMA-positive blood vessels in the peri-infarct and infarct area was evaluated by immunofluorescent staining. The mRNA expression of bFGF, IGF-1, and HGF was detected using RT-PCR assay. Cell apoptosis in the infarcted area was assessed by TUNEL staining, and the p-Akt level was detected using the western blot assay. The mitochondrial ROS production was measured using MitoSOX staining, and mitochondrial dynamics and mitophagy were evaluated with western blotting 7 days after THSWD treatment. THSWD increased the ejection fraction (EF) and fractional shortening (FS) values in the rat hearts; however, no statistical difference was found between the THSWD and MI groups 4 weeks after treatment. Furthermore, THSWD significantly decreased the value of the left ventricular end-systolic volume (LVESV). Compared with the model group, THSWD significantly increased the expression of IGF-1 and bFGF, reduced collagen deposition, promoted angiogenesis, reduced cell apoptosis, and activated the PI3K/Akt signaling pathway. Notably, THSWD significantly decreased mitochondrial ROS production and Fis1 expression. No statistical differences were observed in the expression of mitochondrial LC3B and Mfn1 between the THSWD and control groups. In summary, THSWD may possess a beneficial effect on cardiac function by improving the local ischemic microenvironment and by decreasing mitochondrial fission after MI. Hence, this may present a promising auxiliary strategy in the treatment of ischemic cardiomyopathy such as MI.

Guanxin Danshen Formulation improved the effect of mesenchymal stem cells transplantation for the treatment of myocardial infarction probably via enhancing the engraftment

Although intravenous injection is the most convenient and feasible approach for mesenchymal stem cells (MSCs) delivery, the proportion of donor stem cells in the target myocardium after transplantation is small. It is believed that TCM enhances the effect of stem cell therapy by improving the hostile microenvironment and promoting the migration and survival of stem cells. Guanxin Danshen (GXDS) formulation is one of the main prescriptions for clinical treatment of ischemic heart diseases in China. The purpose of this study was to evaluate the effects of GXDS formulation administration combined with MSCs transplantation on cardiac function improvement, apoptosis, angiogenesis and survival of transplanted cells in an acute model of acute myocardial infarction (MI). After being labeled with GFP, MSCs were transplanted via intravenous injection. Meanwhile, GXDS dripping pills were given by intragastric administration for 4 weeks from 2 days before MI. Echocardiography showed moderate improvement in cardiac function after administration of GXDS formulation or intravenous transplantation of MSCs. However, GXDS formulation combined with MSCs transplantation significantly improved cardiac function after MI. The myocardial infarct size in rats treated with MSCs was similar to that in rats treated with GXDS formulation. However, GXDS formulation combined with MSCs transplantation significantly reduced infarction area. In addition, GXDS formulation combined with MSCs transplantation not only decreased cell apoptosis according to the TUNEL staining, but also enhanced angiogenesis in the peri-infarction and infarction area. Interestingly, the use of GXDS formulation increased the number of injected MSCs in the infarct area. Furthermore, GXDS formulation combined with MSCs transplantation increased SDF-1 levels in the infarcted area, but did not affect the expression of YAP. Our study provided a more feasible and accessible strategy to enhance the migration of stem cells after intravenous injection by oral administration of GXDS formulation. The combination of GXDS formulation and stem cell therapy has practical significance and application prospects in the treatment of ischemic cardiomyopathy such as MI.