The pro-healing effects of heparan sulfate and growth factors are enhanced by the heparinase enzyme: New association for skin wound healing treatment

SIRT1 Mediates the Effects of Sera from Athletes Who Engage in Aerobic Exercise Training in Activating Cells for Wound Healing

Background/Objectives: Exercise training (ET) can improve wound healing and prevent the recurrence of skin lesions. Aerobic ET stimulates the NAD+-dependent deacetylase sirtuin 1 (SIRT1). The beneficial effects of ET and SIRT1 activation in wound healing have been characterized when considered separately. This study aimed to investigate the potential role of SIRT1 as a mediator of the effects of sera isolated from athletes who regularly participate in aerobic ET (middle-distance running, MDR) on cells primarily involved in wound healing. Methods: Human keratinocytes, fibroblasts and endothelial cells were conditioned with sera from middle-distance runners and age-matched sedentary subjects (sed). Cell motility, angiogenesis and the expression of key biomarkers of cell activation were evaluated in the presence or absence of the selective SIRT1 inhibitor EX-527. Results: Higher SIRT1 activity was detected in all of the cell lines conditioned with the MDR group sera compared with that in the cells in the sed group sera. The involvement of SIRT1 was demonstrated by EX-527's selective inhibition. Alongside the increase in SIRT1 activity, a marked increase in migration, invasion and angiogenesis was observed. The levels of E-cadherin decreased while those of integrin β1 and vinculin increased in the keratinocytes and fibroblasts conditioned with the MDR group sera compared to these values with the sed group sera, respectively. Increased levels of differentiation markers, such as involucrin in the keratinocytes, FAP1α in the fibroblasts and CD31 in the endothelial cells, were observed with the MDR group sera compared to these values using the sed group sera. Conclusions: The ex vivo/in vitro approach used here links aerobic ET-induced SIRT1 activity to proper tissue regeneration.

Exploration of biomaterial-tissue integration in heterogeneous microporous annealed particle scaffolds in subcutaneous implants over 12 months

Microporous annealed particle (MAP) scaffolds are comprised of hydrogel microparticles with inter- and intra-particle cross-links that provide structure and cell-scale porosity, making them an increasingly attractive option for injectable tissue augmentation. Many current injectable biomaterials create a substantial foreign body response (FBR), while MAP scaffolds mitigate this response and have the potential to facilitate the formation of new tissue, though this de novo tissue formation is poorly understood. Here, we leverage a subcutaneous implant model to explore the maturation of MAP implants with and without heparin microislands (µislands) over one year to identify the effect of bioactive particles on scaffold maturation. Implants were measured and explanted after 1, 3, 6, and 12 months and analyzed using immunofluorescence staining and RNA-sequencing. No fibrous capsule or significant FBR was observed, and though a significant amount of MAP remains at 12 months, we still see a volume decrease over time. Heparin µislands facilitate increased cell infiltration and recruit a wider variety of cells at 1 month than blank MAP scaffolds, although this effect diminishes after 3 months. Transcriptomics reveal a potential activation of the complement-mediated immune response at 12 months in both groups, possibly associated with pore collapse in the implants. A single 12-month sample avoided this outcome, yielding complete cell infiltration, vascularization, and substantial matrix deposition throughout. Future work will characterize the effect of implantation site and facilitate increased matrix deposition to support the scaffold and prevent pore collapse. STATEMENT OF SIGNIFICANCE: Injectable biomaterials are increasingly used clinically for soft tissue augmentation and regeneration but still face significant issues from the foreign body reaction. While some materials intentionally promote this response to stimulate collagen deposition, porous materials like MAP scaffolds can mitigate the immune response and allow for true tissue integration. However, this integration is poorly understood, particularly on long timescales, as traditional materials are dominated by inflammatory signals. In this work, we leverage a minimally inflammatory subcutaneous implant to investigate the maturation of MAP scaffolds with and without bioactive heparin-containing particles. The results presented here contribute a better understanding of the long-term material-tissue dynamics of MAP scaffolds that can inform future material design for tissue augmentation.

Novel tetrasubstituted 5-Arylamino pyrazoles able to interfere with angiogenesis and Ca2+ mobilization

In the last years, 5-pyrazolyl ureas and 5-aminopyrazoles have been investigated for their antiangiogenetic properties and their potential interaction with the ubiquitous Ca2+ binding protein Calreticulin. Based on the structure of the active compounds I and GeGe-3, novel 5-arylamino pyrazoles 2 and 3 were synthesized through a stepwise procedure. In MTT assays, all the new derivatives proved to be non-cytotoxic against eight different tumor cell lines, normal fibroblasts, and endothelial cells. Furthermore, selected derivatives showed relevant antiangiogenetic properties, resulting more effective than reference molecules I and GeGe-3 in inhibiting HUVEC endothelial tube formation. 5-Arylamino pyrazoles 2a and 2d were identified as the most interesting compounds and significantly prevented tube formation of tumor secretome-stimulated HUVEC. Furthermore, the two compounds inhibited HUVEC migration in wound healing assay and altered cell invasion capability. Additionally, 2a and 2d strongly affected Ca2+ mobilization and cytoskeletal organization of HUVEC cells, being as active as the reference compound GeGe-3. Differently from previous studies, molecular docking simulations suggested a poor affinity of 2a towards Calreticulin, one of the interacting partners of the lead compound GeGe-3. Collectively, this new amino-pyrazole library further extends the structure-activity relationships of the previously prepared derivatives and confirmed the biological attractiveness of this chemical scaffold as antiangiogenetic agents.

Targeting Macrophage Polarization for Reinstating Homeostasis following Tissue Damage

Tissue regeneration and remodeling involve many complex stages. Macrophages are critical in maintaining micro-environmental homeostasis by regulating inflammation and orchestrating wound healing. They display high plasticity in response to various stimuli, showing a spectrum of functional phenotypes that vary from M1 (pro-inflammatory) to M2 (anti-inflammatory) macrophages. While transient inflammation is an essential trigger for tissue healing following an injury, sustained inflammation (e.g., in foreign body response to implants, diabetes or inflammatory diseases) can hinder tissue healing and cause tissue damage. Modulating macrophage polarization has emerged as an effective strategy for enhancing immune-mediated tissue regeneration and promoting better integration of implantable materials in the host. This article provides an overview of macrophages' functional properties followed by discussing different strategies for modulating macrophage polarization. Advances in the use of synthetic and natural biomaterials to fabricate immune-modulatory materials are highlighted. This reveals that the development and clinical application of more effective immunomodulatory systems targeting macrophage polarization under pathological conditions will be driven by a detailed understanding of the factors that regulate macrophage polarization and biological function in order to optimize existing methods and generate novel strategies to control cell phenotype.