The effect of the WKYMVm peptide on promoting mBMSC secretion of exosomes to induce M2 macrophage polarization through the FPR2 pathway

Multifunctional hydrogel-based engineered extracellular vesicles delivery for complicated wound healing

The utilization of extracellular vesicles (EVs) in wound healing has been well-documented. However, the direct administration of free EVs via subcutaneous injection at wound sites may result in the rapid dissipation of bioactive components and diminished therapeutic efficacy. Functionalized hydrogels provide effective protection, as well as ensure the sustained release and bioactivity of EVs during the wound healing process, making them an ideal candidate material for delivering EVs. In this review, we introduce the mechanisms by which EVs accelerate wound healing, and then elaborate on the construction strategies for engineered EVs. Subsequently, we discuss the synthesis strategies and application of hydrogels as delivery systems for the sustained release of EVs to enhance complicated wound healing. Furthermore, in the face of complicated wounds, functionalized hydrogels with specific wound microenvironment regulation capabilities, such as antimicrobial, anti-inflammatory, and immune regulation, used for loading engineered EVs, provide potential approaches to addressing these healing challenges. Ultimately, we deliberate on potential future trajectories and outlooks, offering a fresh viewpoint on the advancement of artificial intelligence (AI)-energized materials and 3D bio-printed multifunctional hydrogel-based engineered EVs delivery dressings for biomedical applications.

Analysis of subsets and localization of macrophages in skin lesions and peripheral blood of patients with keloids

Keloids are a type of abnormal fibrous proliferation disease of the skin, characterized by local inflammation that lacks clear pathogenesis and satisfactory treatment. The phenomenon of distinct phenotypes, including M1 and M2 macrophages, is called macrophage polarization. Recently, macrophage polarization has been suggested to play a role in keloid formation. This study aimed to evaluate the relation between macrophage polarization and keloids and identify novel effective treatments for keloids. Differentially expressed genes were identified via RNA sequencing of the skin tissue of healthy controls and patients with keloids and validated using quantitative PCR. Multiplex immunofluorescence microscopy was used to detect different phenotypes of macrophages in keloid tissues. Finally, quantitative PCR validation of differentially expressed genes and flow cytometry were used to analyze macrophages in the peripheral blood of healthy controls and patients with keloids. Total and M2 macrophages were significantly increased in the local skin tissue and peripheral blood of patients with keloids compared with healthy controls. In addition, inflammation- and macrophage polarization-related differentially expressed genes in keloid tissue showed similar expression patterns in the peripheral blood. This study highlighted an increased frequency of total macrophages and M2 polarization in the local skin tissue and peripheral blood of patients with keloids. This systematic macrophage polarization tendency also indicates a potential genetic predisposition to keloids. These findings suggest the possibility of developing new diagnostic and therapeutic indicators for keloids focusing on macrophages.

Harnessing bone marrow mesenchymal stem cell-derived extracellular vesicles and biomimetic peptide WKYMVm in self-healing hydrogel for enhanced bone repair in femoral defects

Skeletal disorders pose significant challenges to health and quality of life, underscoring the critical need for innovative bone repair methods. Recent studies have spotlighted the promising role of extracellular vesicles (EVs) derived from bone marrow mesenchymal stem cells (BMSCs) in conjunction with biomimetic peptide (BP) WKYMVm (WK) for bone repair. This research leveraged a self-healing hydrogel as a carrier, effectively loading EVs and WK to enhance treatment efficacy. Through the regulation of vascular formation and osteoblast differentiation, notable advancements were achieved in mending femoral defect bone injuries, offering new possibilities for addressing bone metabolic disorders. The detailed methodology encompassed hydrogel preparation, EVs and WK loading, in vitro cell studies, and rat model experiments. Results unveiled that graphene oxide gelatin hydrogel loaded with wkymvm and extracellular vesicles (GOG@WK-EVs) notably bolstered osteogenic differentiation of bone cells and angiogenesis, while impeding osteoclast differentiation, culminating in potent bone regeneration within femoral defects.

Formyl peptide receptors in bone research

PURPOSE/AIM OF THE STUDY

The formyl peptide receptor (FPR) participates in the immune response, with roles in infection and inflammation. In this review article, we summarize the current literature on these roles before discussing the function of FPRs in the pathogenesis of musculoskeletal disorders including osteoarthritis (OA), degenerative disc disease (DDD), and rheumatoid arthritis (RA). Additionally, we discuss the potential diagnostic and therapeutic roles of FPRs in these domains.

METHODS

PubMed and Ovid MEDLINE searches were performed from 1965 through March 2022. Keywords included "FPR, tissue expression, inflammation, infection, musculoskeletal disorder, bone, rheumatoid arthritis, osteoarthritis, degenerative disc disease, mitochondria."

RESULTS

Sixty-nine studies were included in this review article. FPRs appear to be ubiquitous in the pathogenesis, diagnosis, and treatment of common musculoskeletal disorders. They can potentially be utilized for the earlier diagnosis of OA and DDD. They may be employed with mesenchymal stem cells (MSCs) to reverse OA and DDD pathologies. With anti-inflammatory, anti-osteolytic, and pro-angiogenic functions, they may broaden treatment options in RA.

CONCLUSIONS

FPRs appear to be heavily involved in the pathogenesis of common musculoskeletal conditions, including arthritis, degenerative disc disease, and rheumatoid arthritis. Furthermore, they demonstrate much promise in the diagnosis and treatment of these conditions. Their roles should continue to be explored.

Bioactive peptides for boosting stem cell culture platform: Methods and applications

Peptides, short protein fragments, can emulate the functions of their full-length native counterparts. Peptides are considered potent recombinant protein alternatives due to their specificity, high stability, low production cost, and ability to be easily tailored and immobilized. Stem cell proliferation and differentiation processes are orchestrated by an intricate interaction between numerous growth factors and proteins and their target receptors and ligands. Various growth factors, functional proteins, and cellular matrix-derived peptides efficiently enhance stem cell adhesion, proliferation, and directed differentiation. For that, peptides can be immobilized on a culture plate or conjugated to scaffolds, such as hydrogels or synthetic matrices. In this review, we assess the applications of a variety of peptides in stem cell adhesion, culture, organoid assembly, proliferation, and differentiation, describing the shortcomings of recombinant proteins and their full-length counterparts. Furthermore, we discuss the challenges of peptide applications in stem cell culture and materials design, as well as provide a brief outlook on future directions to advance peptide applications in boosting stem cell quality and scalability for clinical applications in tissue regeneration.

WKYMVm Works by Targeting Immune Cells

WKYMVm (Trp-Lys-Tyr-Met-Val-D-Met) is a synthetic hexapeptide identified as a potent agonist of FPRs. FPRs are widely expressed on the cell membrane of immune cells. Therefore, WKYMVm participates in the regulation of immune cells by activating FPRs, and plays a therapeutic role in infections, tumors, autoimmune diseases and so on. WKYMVm can promote the chemotactic migration, increase the bactericidal activity of neutrophils and monocytes. WKYMVm also regulates the number and polarization of macrophages, affects the maturation of DCs and the differentiation of T cells, and promotes the activation and chemotaxis of NK cells. These functions make WKYMVm a candidate drug for immunotherapy. In this paper, we summarize the regulatory effects and underlying mechanisms of WKYMVm on six immune cells (neutrophils, monocytes, macrophages, DCs, T cells and NK cells) to increase comprehensive understanding and promote further research on WKYMVm.

Engineering exosomes for bone defect repair

Currently, bone defect repair is still an intractable clinical problem. Numerous treatments have been performed, but their clinical results are unsatisfactory. As a key element of cell-free therapy, exosome is becoming a promising tool of bone regeneration in recent decades, because of its promoting osteogenesis and osteogenic differentiation function in vivo and in vitro. However, low yield, weak activity, inefficient targeting ability, and unpredictable side effects of natural exosomes have limited the clinical application. To overcome the weakness, various approaches have been applied to produce engineering exosomes by regulating their production and function at present. In this review, we will focus on the engineering exosomes for bone defect repair. By summarizing the exosomal cargos affecting osteogenesis, the strategies of engineering exosomes and properties of exosome-integrated biomaterials, this work will provide novel insights into exploring advanced engineering exosome-based cell-free therapy for bone defect repair.

Therapeutic potential of WKYMVm in diseases

The synthetic hexapeptide WKYMVm, screened from a synthetic peptide library, has been identified as an agonist of FPRs with the strongest activating effect on FPR2. WKYMVm plays an anti-inflammatory role in most inflammatory diseases by increasing the chemotaxis of phagocytes and regulating the secretion of inflammatory factors. WKYMVm can inhibit or promote the progression of different types of tumors, which depends on the regulation of WKYMVm on various components such as immune cells, inflammatory factors, chemokines, and tumor epithelial cells. Another major function of WKYMVm is to promote angiogenesis, which is reflected in its therapeutic value in ischemic diseases, wound healing and bone repair. In addition to the above functions, this paper also reviews the effects of WKYMVm on fibrosis, insulin resistance, osteolytic diseases and neurodegenerative diseases. By summarizing related studies, this review can increase people’s comprehensive understanding of WKYMVm, promote its broad and in-depth research, and help to exert its therapeutic value as soon as possible.