Effect of Cytomodulin-10 (TGF-ß1 analogue) on wound healing by primary intention in a murine model

Exosome-mimetic vesicles derived from fibroblasts carrying matrine for wound healing

Background

Chronic skin wounds are a leading cause of hospital admissions and reduced life expectancy among older people and individuals with diabetes. Delayed wound healing is often attributed to a series of cellular abnormalities. Matrine, a well-studied component found in Sophora flavescens, is recognized for its anti-inflammatory effects. However, its impact on wound healing still remains uncertain. This study aims to explore the potential of matrine in promoting wound healing.

Methods

In this study, we utilized gradient extrusion to produce fibroblast-derived exosome-mimetic vesicles as carriers for matrine (MHEM). MHEM were characterized using transmission electron microscopy and dynamic light scattering analysis. The therapeutic effect of MHEM in wound healing was explored in vitro and in vivo.

Results

Both matrine and MHEM enhanced the cellular activity as well as the migration of fibroblasts and keratinocytes. The potent anti-inflammatory effect of matrine diluted the inflammatory response in the vicinity of wounds. Furthermore, MHEM worked together to promote angiogenesis and the expression of transforming growth factor β and collagen I. MHEM contained growth factors of fibroblasts that regulated the functions of fibroblasts, keratinocytes and monocytes, which synergistically promoted wound healing with the anti-inflammatory effect of matrine.

Conclusions

MHEM showed enhanced therapeutic efficacy in the inflammatory microenvironment, for new tissue formation and angiogenesis of wound healing.

Injectable silk fibroin peptide nanofiber hydrogel composite scaffolds for cartilage regeneration

Transforming growth factor-β1 (TGF-β1) is essential for cartilage regeneration, but its susceptibility to enzymatic denaturation and high cost limit its application. Herein, we report Ac-LIANAKGFEFEFKFK-NH2 (LKP), a self-assembled peptide nanofiber hydrogel that can mimic the function of TGF-β1. The LKP hydrogel is simple to synthesize, and in vitro experiments confirmed its good biocompatibility and cartilage-promoting ability. However, LKP hydrogels suffer from poor mechanical properties and are prone to fragmentation; therefore, we prepared a series of injectable hydrogel composite scaffolds (SF-GMA/LKP) by combining LKP with glycidyl methacrylate (GMA)-modified silk fibroin (SF). SF-GMA/LKP composite scaffolds instantaneously induced in-situ filling of cartilage defects and, at the same time, relied on the interaction between LKP and SF-GMA interaction to prolong the duration of action of LKP. The SF-GMA/LKP10 and SF-GMA/LKP20 composite scaffolds had the best effect on neocartilage and subchondral bone reconstruction. This composite hydrogel scaffold can be used for high-quality cartilage repair.

Peptide-Based Biomaterials for Bone and Cartilage Regeneration

The healing of osteochondral defects (OCDs) that result from injury, osteochondritis, or osteoarthritis and bear lesions in the cartilage and bone, pain, and loss of joint function in middle- and old-age individuals presents challenges to clinical practitioners because of non-regenerative cartilage and the limitations of current therapies. Bioactive peptide-based osteochondral (OC) tissue regeneration is becoming more popular because it does not have the immunogenicity, misfolding, or denaturation problems associated with original proteins. Periodically, reviews are published on the regeneration of bone and cartilage separately; however, none of them addressed the simultaneous healing of these tissues in the complicated heterogeneous environment of the osteochondral (OC) interface. As regulators of cell adhesion, proliferation, differentiation, angiogenesis, immunomodulation, and antibacterial activity, potential therapeutic strategies for OCDs utilizing bone and cartilage-specific peptides should be examined and investigated. The main goal of this review was to study how they contribute to the healing of OCDs, either alone or in conjunction with other peptides and biomaterials.

Comparison of multiple synthetic chondroinductive factors in pellet culture against a TGF-β positive control

Despite the advances in surgical and cell therapy regenerative techniques for cartilage repair, the challenge is to overcome an inferior fibrocartilage repair tissue. In vitro, TGF-β1 and TGF-β3 are the primary growth factors employed to induce chondrogenic differentiation. However, the clinical application of native proteins may present challenges regarding stability, cost, or reproducibility. Therefore, there remains an unmet clinical need for the identification of small chondroinductive synthetic molecules. From the literature, two peptides-CM10 and CK2.1-appear to be promising candidates; however, they have not been directly compared to TGF-β with human bone marrow-derived stem cells (hBMSCs). Similarly, two promising compounds-kartogenin and SM04690-have been reported in the literature to exhibit chondroinductive potential in vivo and in vitro; however, kartogenin was not directly compared against TGF-β. In the current study, we evaluated the chondroinductive potential of CM10, CK2.1, kartogenin, and SM04690, and directly compared them to each other and to a TGF-β3 positive control. Following 21 days of culture, none of the evaluated chondrogenic factors, either individually or even in combinations of two, resulted in a higher gene expression of chondrogenic markers as compared to TGF-β3. Additionally, no collagen II gene expression was detected except in the TGF-β3 positive control group. Given that the evaluated factors have confirmed efficacy in the literature, but not in the current study with a positive control, there may be value in the future identification of new chondroinductive factors that are less situation-dependent, with rigorous evaluations of their effect on chondrogenesis using positive controls.

Research progress of functional motifs based on growth factors in cartilage tissue engineering: A review

Osteoarthritis is a chronic degenerative joint disease that exerts significant impacts on personal life quality, and cartilage tissue engineering is a practical treatment in clinical. Various growth factors are involved in cartilage regeneration and play important roles therein, which is the focus of current cartilage repair strategy. To compensate for the purification difficulty, high cost, poor metabolic stability, and circulating dilution of natural growth factors, the concept of functional motifs (also known as mimetic peptides) from original growth factor was introduced in recent studies. Here, we reviewed the selection mechanisms, biological functions, carrier scaffolds, and modification methods of growth factor-related functional motifs, and evaluated the repair performance in cartilage tissue engineering. Finally, the prospects of functional motifs in researches and clinical application were discussed.

Hybrid membrane of flat silk cocoon and carboxymethyl chitosan formed through hot pressing promotes wound healing and repair in a rat model

Clinical wound management is always a relatively urgent problem. Moreover, wounds, especially severe wounds with excessive tension or excessive movement are prone to tissue infection, necrosis, and other negative effects during healing. Therefore, research has aimed to develop low-cost complementary treatments to address the urgent need for an innovative low-cost dressing that can adapt to high mechanical requirements and complex wound conditions. At present, tissue engineering to produce artificial skin with a structure similar to that of normal skin is one effective method to solve this challenge in the regeneration and repair of serious wounds. The present study hot pressed flat silk cocoons (FSC) with carboxymethyl chitosan (CMCS) to generate a cross-linked binding without enzymes or cross-linking agents that simulated the 3D structural composites of the skin cuticle. This hybrid membrane showed potential to reduce inflammatory cells and promote neovascularization in skin wound repair. After hot pressing at 130°C and 20 Mpa, the FSC/CMCS composite material was denser than FSC, showed strong light transmission, and could be arbitrarily cut. Simulating the normal skin tissue structure, the hybrid membrane overcame the poor mechanical properties of traditional support materials. Moreover, the combination of protein and polysaccharide simulated the extracellular matrix, thus providing better biocompatibility. The results of this study also demonstrated the excellent mechanical properties of the FSC/CMCS composite support material, which also provided a low-cost and environmentally friendly process for making dressings. In addition, the results of this study preliminarily reveal the mechanism by which the scaffolds promoted the healing of full-thickness skin defects on the back of SD rats. In vivo experiments using a full-thickness skin defect model showed that the FSC/CMCS membranes significantly promoted the rate of wound healing and also showed good effects on blood vessel formation and reduced inflammatory reactions. This bionic support structure, with excellent repair efficacy on deep skin defect wounds, showed potential to further improve the available biomaterial systems, such as skin and other soft tissues.

Articular cartilage reconstruction with TGF-β1-simulating self-assembling peptide hydrogel-based composite scaffold

Transforming growth factor-β (TGF-β) is an important inducing factor for the differentiation of mesenchymal stem cells and the secretion of collagen II, but the inaccessibility and instability limit its application in clinical practice. In this study, the TGF-β1-simulating peptide LIANAK (CM) was connected with the self-assembling peptide Ac-(RADA)₄-CONH₂ (RAD) to obtain the functionalized self-assembling peptide Ac-(RADA)₄-GG-LIANAK-CONH₂ (RAD-CM). The results indicated that the CM-functionalized RAD hydrogel contributed to the enhanced expressions of chondrogenic genes and extracellular matrix deposition. The self-assembling peptides were then combined with decellularized cartilage extracellular matrix (DCM) to construct a composite scaffold for articular cartilage repair. The CM-functionalized composite scaffold RAD/RAD-CM/DCM (R/C/D) exhibited good bioactivity and structural stability and exhibited satisfactory performance in promoting neocartilage restoration and the reconstruction of the osteochondral unit. This study provides a promising strategy for in situ cartilage regeneration via the stable presentation of TGF-β1-simulating peptide. STATEMENT OF SIGNIFICANCE: Deficiency of effective chondrogenic inducers (especially, the TGF-β family) significantly limits the self-regeneration of cartilage in osteochondral defect cases. Oligopeptide LIANAK, named CM, could simulate TGF-β1's bioactivity with particular structure, but traditional chemical crosslinking to polymer scaffolds resulted in risks of safety and complication, which is unfavorable for clinical applications. Here, self-assembling peptide RAD was used to load CM, to obtain a TGF-β1 mimetic peptide hydrogel. Depending on the homology (amino acids) of RAD and CM, the synthesis of the whole peptide only needs simply extended sequences of CM following that of RAD by automated solid-phase peptide synthesis. The modified peptide effectively demonstrated osteochondrogenic bioactivity, ensured the convenience, safety, and mass production, which displayed great potential in tissue engineering research and translational medicine.

Strategies to Control or Mimic Growth Factor Activity for Bone, Cartilage, and Osteochondral Tissue Engineering

Growth factors play a critical role in tissue repair and regeneration. However, their clinical success is limited by their low stability, short half-life, and rapid diffusion from the delivery site. Supraphysiological growth factor concentrations are often required to demonstrate efficacy but can lead to adverse reactions, such as inflammatory complications and increased cancer risk. These issues have motivated the development of delivery systems that enable sustained release and controlled presentation of growth factors. This review specifically focuses on bioconjugation strategies to enhance growth factor activity for bone, cartilage, and osteochondral applications. We describe approaches to localize growth factors using noncovalent and covalent methods, bind growth factors via peptides, and mimic growth factor function with mimetic peptide sequences. We also discuss emerging and future directions to control spatiotemporal growth factor delivery to improve functional tissue repair and regeneration.

Evaluation of the in vivo wound healing potential of the lipid fraction from activated platelet-rich plasma

Previous in vitro studies suggest a direct relevance for the peptide-free lipid fraction (LF) of platelet-rich plasma (PRP) in biological mechanisms related to wound healing. However, there are no scientific reports to date on the wound healing activities of this lipid component in vivo. Thus, the present study provides a scientific evaluation for the wound healing potential of the lipid portion of the activated PRP. For the wound healing activity assessment, in vivo full-thickness excisional wounds were created on the dorsal skin of Sprague-Dawley rats. Lipid extract from pooled PRP was applied topically to the wounds on 0, 3, and 7 days after injury. Histological assessment of epidermal and dermal regeneration, granulation tissue thickness and angiogenesis by Sirius red and Masson's trichrome staining, in addition to immunohistochemical staining for transforming growth factor beta-1 (TGF-β1), collagen type I (COL I), and collagen type III (COL III) were performed on skin biopsies at 3, 7 and 14 days. The total histological scores of the LF group were significantly higher than the 25% dimethylsulfoxide-control group. According to the immunohistochemical staining, the observed expression changes for TGF-β1, COL I and III at 3, 7, and 14 days after wounding were significantly better in the study group than the control group. Furthermore, COL I/III ratio in the lipid extract-treated group at day 14 was much higher than that of the control group. Meanwhile, analysis of the data also indicated that the LF has less positive effects on all evaluated parameters than PRP. From the present data, it could be concluded that the peptide-free LF of PRP has potent wound healing capacity in vivo for cutaneous wounds, although not as much as that of PRP. Strengthening our understanding of the wound healing potential of lipid components of PRP and platelet-derived lipid factors may provide new avenues for improving the healing process of a wound with elevated protease activity.

Beneficial effects of a novel shark-skin collagen dressing for the promotion of seawater immersion wound healing

BACKGROUND

Wounded personnel who work at sea often encounter a plethora of difficulties. The most important of these difficulties is seawater immersion. Common medical dressings have little effect when the affected area is immersed in seawater, and only rarely dressings have been reported for the treatment of seawater-immersed wounds. The objective of this study is to develop a new dressing which should be suitable to prevent the wound from seawater immersion and to promote the wound healing.

METHODS

Shark skin collagen (SSC) was purified via ethanol de-sugaring and de-pigmentation and adjusted for pH. A shark skin collagen sponge (SSCS) was prepared by freeze-drying. SSCS was attached to an anti-seawater immersion polyurethane (PU) film (SSCS + PU) to compose a new dressing. The biochemical properties of SSC and physicochemical properties of SSCS were assessed by standard methods. The effects of SSCS and SSCS + PU on the healing of seawater-immersed wounds were studied using a seawater immersion rat model. For the detection of SSCS effects on seawater-immersed wounds, 12 SD rats, with four wounds created in each rat, were divided into four groups: the 3rd day group, 5th day group, 7th day group and 12th day group. In each group, six wounds were treated with SSCS, three wounds treated with chitosan served as the positive control, and three wounds treated with gauze served as the negative control. For the detection of the SSCS + PU effects on seawater-immersed wounds, 36 SD rats were divided into three groups: the gauze (GZ) + PU group, chitosan (CS) + PU group and SSCS + PU group, with 12 rats in each group, and two wounds in each rat. The wound sizes were measured to calculate the healing rate, and histomorphology and the immunohistochemistry of the CD31 and TGF-β expression levels in the wounded tissues were measured by standard methods.

RESULTS

The results of Ultraviolet-visible (UV-vis) spectrum, Fourier-transform infrared (FTIR) spectrum, circular dichroism (CD) spectra, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and amino acid composition analyses of SSC demonstrated that SSC is type I collagen. SSCS had a homogeneous porous structure of approximately 200 μm, porosity rate of 83.57% ± 2.64%, water vapor transmission ratio (WVTR) of 4500 g/m², tensile strength of 1.79 ± 0.41 N/mm, and elongation at break of 4.52% ± 0.01%. SSCS had significant beneficial effects on seawater-immersed wound healing. On the 3rd day, the healing rates in the GZ negative control, CS positive control and SSCS rats were 13.94% ± 5.50%, 29.40% ± 1.10% and 47.24% ± 8.40%, respectively. SSCS also enhanced TGF-β and CD31 expression in the initial stage of the healing period. The SSCS + PU dressing effectively protected wounds from seawater immersion for at least 4 h, and accelerated re-epithelialization, vascularization and granulation formation of seawater-immersed wounds in the earlier stages of wound healing, and as well as significantly promoted wound healing. The SSCS + PU dressing also enhanced expression of TGF-β and CD31. The effects of SSCS and SSCS + PU were superior to those of both the chitosan and gauze dressings.

CONCLUSIONS

SSCS has significant positive effects on the promotion of seawater-immersed wound healing, and a SSCS + PU dressing effectively prevents seawater immersion, and significantly promotes seawater-immersed wound healing.

Injectable Peptide Decorated Functional Nanofibrous Hollow Microspheres to Direct Stem Cell Differentiation and Tissue Regeneration

Injectable microspheres are attractive stem cell carriers for minimally invasive procedures. For tissue regeneration, the microspheres need to present the critical cues to properly direct stem cell differentiation. In natural extracellular matrix (ECM), growth factors (GFs) and collagen nanofibers provide critical chemical and physical cues. However, there have been no reported technologies that integrate synthetic nanofibers and GFs into injectable microspheres. In this study, we synthesized functional nanofibrous hollow microspheres (FNF-HMS), which can covalently bind GF-mimicking peptides. Two different GF-mimicking peptides, Transforming Growth Factor-β1 mimicking peptide Cytomodulin (CM) and Bone Morphogenetic Protein-2 mimicking peptide P24, were separately conjugated onto the FNF-HMS to induce distinct differentiation pathways of rabbit bone marrow-derived mesenchymal stem cells (BMSCs). While no existing biomaterials were reported to successfully deliver CM to induce chondrogenesis, the developed FNF-HMS were shown to effectively present CM to BMSCs and successfully induced their chondrogenesis for cartilage formation in both in vitro and in vivo studies. In addition, P24 was conjugated onto the newly developed FNF-HMS and was capable of retaining its bioactivity and inducing ectopic bone formation in nude mice. These results demonstrate that the novel FNF-HMS can effectively deliver GF-mimicking peptides to modulate stem cell fate and tissue regeneration.