Overcoming the Inflammatory Stage of Non-Healing Wounds: In Vitro Mechanism of Action of Negatively Charged Microspheres (NCMs)

Advanced glycation end products regulate macrophage apoptosis and influence the healing of diabetic foot wound through miR-361-3p/CSF1R and PI3K/AKT pathway

Background

Diabetic foot ulcers (DFUs) are a severe complication of diabetes. Persistent inflammation and impaired vascularization present considerable challenges in tissue wound healing. The aim of this study was to identify the crucial regulators of DFU wound healing and investigate their specific mechanisms in DFU.

Methods

DFU RNA sequencing data were obtained to identify crucial feature genes. The expression levels of the feature genes and their corresponding microRNAs (miRNAs) were verified in clinical samples. Subsequently, the expression of CD68 was determined in DFU and non-diabetic foot skin samples. RAW 264.7 cells were treated with advanced glycation end products (AGEs) to determine their viability and apoptosis. Finally, the roles of the selected crucial genes and their corresponding miRNAs were investigated using in vitro experiments and a mouse model of diabetes.

Results

Bioinformatic analysis showed that five crucial feature genes (CORO1A, CSF1R, CTSH, NFE2L3, and SLC16A10) were associated with DFU wound healing. The expression validation showed that miR-361-3p-CSF1R had a significant negative correlation and was thus selected for further experiments. AGEs significantly inhibited the viability of RAW 264.7 cells and enhanced their apoptosis; furthermore, the AGEs significantly downregulated CSF1R and increased miR-361-3p levels compared with the control cells. Additionally, inhibition of miR-361-3p decreased the cell apoptosis caused by AGEs and increased the levels of p-AKT/AKT and p-PI3K/PI3K, whereas CSF1R knockdown reversed the effects of miR-361-3p. In vivo experiments showed that miR-361-3p inhibition promoted wound healing in diabetic mice and regulated PI3K/AKT levels.

Conclusions

AGEs may regulate macrophage apoptosis via the miR-361-3p/CSF1R axis and PI3K/AKT pathway, thereby influencing DFU wound healing.

Microparticles Decorated with Cell-Instructive Surface Chemistries Actively Promote Wound Healing

Wound healing is a complex biological process involving close crosstalk between various cell types. Dysregulation in any of these processes, such as in diabetic wounds, results in chronic nonhealing wounds. Fibroblasts are a critical cell type involved in the formation of granulation tissue, essential for effective wound healing. 315 different polymer surfaces are screened to identify candidates which actively drive fibroblasts toward either pro- or antiproliferative functional phenotypes. Fibroblast-instructive chemistries are identified, which are synthesized into surfactants to fabricate easy to administer microparticles for direct application to diabetic wounds. The pro-proliferative microfluidic derived particles are able to successfully promote neovascularization, granulation tissue formation, and wound closure after a single application to the wound bed. These active novel bio-instructive microparticles show great potential as a route to reducing the burden of chronic wounds.

Preclinical safety of negatively charged microspheres (NCMs): optimization of radiolabeling for in vivo and ex vivo biodistribution studies after topical administration on full-thickness wounds in a rat model

Negatively charged microspheres (NCMs) are postulated as a new form of treatment for chronic wounds. Despite the efficacy shown at clinical level, more studies are required to demonstrate their safety and local effect. The objective of the work was to confirm the lack of NCM systemic absorption performing a biodistribution study of the NCMs in an open wound rat animal model. To this end, radiolabeling of NCMs with technetium-99m was optimized and biodistribution studies were performed by in vivo SPEC/CT imaging and ex vivo counting during 24 h after topical administration. The studies were performed on animals treated with a single or repeated dose to study the effect of macrophages during a prolonged treatment. NCM radiolabeling was achieved in a simple, efficient and stable manner with high yield. SPECT/CT images showed that almost all NCMs (about 85 %) remained on the wound for 24 h either after single or multiple administrations. Ex vivo biodistribution studies confirmed that there was no accumulation of NCMs in any organ or tissue except in the wound area, suggesting a lack of absorption. In conclusion, NCMs can be considered safe as local wound treatment since they remain at the administration area.

Clinical and Histological Outcomes of Negatively Charged Polystyrene Microspheres Applied Daily Versus Three Times per Week in Hard-to-Heal Diabetic Foot Ulcers: A Randomized Blinded Controlled Trial

Negatively charged polystyrene microspheres (NCMs) have been demonstrated as a novel and effective therapy for managing hard-to-heal diabetic foot ulcers (DFUs). However, one limitation of this therapy is that the protocol is based on daily application, which sometimes does not fit local protocols of wound care. Thus, we aimed to analyze the safety and efficacy of a new dose regimen. We conducted a randomized blinded controlled trial in a specialized diabetic foot unit between May 2019 and February 2021 with a total of 30 patients who had neuropathic or neuroischemic DFUs that had not responded after four weeks of standard treatment. Patients were randomized consecutively into a group that received daily application (control) or one that received applications three times per week (experimental). The clinical outcomes were evaluated using the Wollina score and wound-area reduction (WAR) weekly during a treatment period of 28 days. The histological outcomes were assessed using a soft-tissue punch biopsy (3 mm) at 0, 14, and 28 days to evaluate cellular proliferation. The Wollina scores were higher at the end of treatment by week 4 in both groups, but the differences were not significant between groups. The averages were 6 (5, 7) points in Experimental group (EG) and 6 (6,7) points in Control group (CG) (p = 0.848). Wound area reduction at day 28 was 53.57 [37.43, 79.16] % in the CG and 79.37 [42.74, 93.57] % in the EG, without differences among groups (p = 0.305). Cellular proliferation was similar in both groups at day 28. Application three times per week showed similar clinical and histological outcomes to those of daily application, both dose regimens demonstrated significant improvement of granulation tissue formation and WAR during the treatment.

The Role of Recombinant Secretory Leukocyte Protease Inhibitor to CD163, FGF-2, IL-1 and IL-6 Expression in Skin Wound Healing

Background

The wound healing process can be optimized through the addition of a biomaterial such as recombinant secretory leukocyte protease inhibitor (rSLPI). The SLPI is a non-glycosylated proteomic material that inhibits protease enzymes and has anti-inflammatory properties, thus accelerating wound healing. This study analyzed the administration of rSLPI doses 0.04 cc and 0.06 cc in skin wound healing on the CD163 expression of macrophages and cytokines such as interleukin 1 (IL-1), interleukin 6 (IL-6) and fibroblast growth factor 2 (FGF-2).

Materials and Methods

rSLPI produced from Escherichia coli TOP10 as the cloning host, BL21 (DE3) strains as the expression host and pET30a plasmids were used for the expression system construction. The wound was created on Wistar rat dorsal skin, then rSLPI 0.04 cc and 0.06 cc was administered. In the next four days, the back skin was biopsied and stained by immunohistochemistry to analyze the CD163, FGF-2, IL-1 and IL-6 expression.

Results

The administration of rSLPI increased CD163 and FGF-2 expression dependent on dose (p<0.05). On the other hand, administration of rSLPI decreased IL-1 and IL-6 expression depending on dose (p <0.05).

Conclusion

The administration of rSLPI is able to accelerate the wound healing process by increasing the CD163 and FGF-2 expression. The cytokines such as IL-1 and IL-6 decreased depending on rSLPI doses.

Human Hair Follicle-Derived Mesenchymal Stromal Cells from the Lower Dermal Sheath as a Competitive Alternative for Immunomodulation

Mesenchymal stromal cells (MSCs) have unique immunomodulatory capacities. We investigated hair follicle-derived MSCs (HF-MSCs) from the dermal sheath, which are advantageous as an alternative source because of their relatively painless and minimally risky extraction procedure. These cells expressed neural markers upon isolation and maintained stemness for a minimum of 10 passages. Furthermore, HF-MSCs showed responsiveness to pro-inflammatory environments by expressing type-II major histocompatibility complex antigens (MHC)-II to a lesser extent than adipose tissue-derived MSCs (AT-MSCs). HF-MSCs effectively inhibited the proliferation of peripheral blood mononuclear cells equivalently to AT-MSCs. Additionally, HF-MSCs promoted the induction of CD4+CD25+FOXP3+ regulatory T cells to the same extent as AT-MSCs. Finally, HF-MSCs, more so than AT-MSCs, skewed M0 and M1 macrophages towards M2 phenotypes, with upregulation of typical M2 markers CD163 and CD206 and downregulation of M1 markers such as CD64, CD86, and MHC-II. Thus, we conclude that HF-MSCs are a promising source for immunomodulation.

Recent Discoveries in Nanoparticle-Macrophage Interactions: In Vitro Models for Nanosafety Testing and Novel Nanomedical Approaches for Immunotherapy

Nanoparticles (NPs) offer unique properties for biomedical applications, leading to new nanomedicines [...].

Fibroblasts upregulate expression of adhesion molecules and promote lymphocyte retention in 3D fibroin/gelatin scaffolds

Bioengineered scaffolds are crucial components in artificial tissue construction. In general, these scaffolds provide inert three-dimensional (3D) surfaces supporting cell growth. However, some scaffolds can affect the phenotype of cultured cells, especially, adherent stromal cells, such as fibroblasts. Here we report on unique properties of 3D fibroin/gelatin materials, which may rapidly induce expression of adhesion molecules, such as ICAM-1 and VCAM-1, in cultured primary murine embryonic fibroblasts (MEFs). In contrast, two-dimensional (2D) fibroin/gelatin films did not show significant effects on gene expression profiles in fibroblasts as compared to 3D culture conditions. Interestingly, TNF expression was induced in MEFs cultured in 3D fibroin/gelatin scaffolds, while genetic or pharmacological TNF ablation resulted in diminished ICAM-1 and VCAM-1 expression by these cells. Using selective MAPK inhibitors, we uncovered critical contribution of JNK to 3D-induced upregulation of these adhesion molecules. Moreover, we observed ICAM-1/VCAM-1-dependent adhesion of lymphocytes to fibroblasts cultured in 3D fibroin/gelatin scaffolds, but not on 2D fibroin/gelatin films, suggesting functional reprogramming in stromal cells, when exposed to 3D environment. Finally, we observed significant infiltration of lymphocytes into 3D fibroin/gelatin, but not into collagen scaffolds in vivo upon subcapsular kidney implantation in mice. Together our data highlight the important features of fibroin/gelatin scaffolds, when they are produced as 3D sponges rather than 2D films, which should be considered when using these materials for tissue engineering.

•

3D, but not 2D fibroin-based scaffolds promote expression of adhesion molecules in murine fibroblasts.

•

Overexpression of adhesion molecules in 3D fibroin/gelatin-cultured fibroblasts is TNF- and JNK-dependent.

•

Culturing of fibroblasts in 3D fibroin/gelatin scaffolds promotes adhesion of T-lymphocytes.

•

Implantation of 3D fibroin/gelatin scaffolds in vivo induces infiltration and clustering of T- and B-lymphocytes.

Investigating the effects of walnut ointment on non-healing burn wounds

Effective treatments for non-healing burn wounds are an unmet need for 95% of burn sufferers. Approaches currently available to treat non-healing burn wounds are not satisfactory due to undesirable side-effects or expense. The anti-oxidation and antibacterial activities of walnuts are recommended for treating chronic diseases. Walnut ointment has been developed and successfully applied to treat non-healing burn wounds in our hospital for decades. We report herein a detailed retrospective case review examining patients' response to the walnut ointment. The walnut ointment has shortened healing time of non-healing burn wounds and improved clinical outcomes. In order to investigate the mechanism of action, walnut ointment has been applied on wounds of porcine full-thickness burn wound models. Histological and immunohistochemical analysis indicated our walnut ointment supports wound healing through promoting keratinocyte proliferation and differentiation. Taken together, we recommend the walnut ointment offers an effective and economical treatment for patients presenting with non-healing burn wounds.