Hydroxyapatite Particles Induced Modulation of Collagen Expression and Secretion in Primary Human Dermal Fibroblasts

Nanohydroxyapatite Coating Attenuates Fibrotic and Immune Responses to Promote Keratoprosthesis Biointegration in Advanced Ocular Surface Disorders

Keratoprosthesis (KPro) implantation is frequently the only recourse for patients with severe corneal disease. However, problems arise due to inadequate biointegration of the KPro, particularly the PMMA optical cylinder, such as tissue detachment, tissue melting, or eye-threatening infection in the interface. Here, using the AuroKPro as a model prosthesis, a surface functionalization approach─coating the optical cylinder with nanohydroxyapatite (nHAp)─was trialed in rabbit eyes with and without a proceeding chemical injury. In chemically injured eyes, which simulated total limbal epithelial stem cell deficiency, clear benefits were conferred by the coating. The total modified Hackett-McDonald score and area of tissue apposition differences 12 weeks after implantation were 5.0 and 22.5%, respectively. Mechanical push-in tests revealed that 31.8% greater work was required to detach the tissues. These differences were less marked in uninjured eyes, which showed total score and tissue apposition differences of 2.5 and 11.5%, respectively, and a work difference of 23.5%. The improved biointegration could be contributed by the attenuated expression of fibronectin (p = 0.036), collagen 3A1 (p = 0.033), and α-smooth muscle actin (p = 0.045)─proteins typically upregulated during nonadherent fibrous capsule envelopment of bioinert material─adjacent to the optical cylinders. The coating also appeared to induce a less immunogenic milieu in the ocular surface tissue, evidenced by the markedly lower expression of tear proteins associated with immune and stimulus responses. Collectively, the level of these tear proteins in eyes with coated prostheses was 1.1 ± 13.0% of naïve eyes: substantially lower than with noncoated KPros (246.5 ± 79.3% of naïve, p = 0.038). Together, our results indicated that nHAp coating may reduce the risk of prosthesis failure in severely injured eyes, which are representative of the cohort of KPro patients.

Long acting tariquidar loaded stearic acid-modified hydroxyapatite enhances brain penetration and antitumor effect of temozolomide

Temozolomide (TMZ) is the first line chemotherapy for glioblastoma (GBM) treatment, but the P-glycoprotein (P-gp) expressed in blood-brain barrier (BBB) will pump out TMZ from the brain leading to decreased TMZ concentration. Tariquidar (TQD), a selective and potent P-gp inhibitor, may be suitable for combination therapy to increase concentration of TMZ in brain. Hydroxyapatite (HAP) is a biodegradable material with sustained release characteristics, and stearic acid surface-modified HAP (SA-HAP) can increase hydrophobicity to facilitate TQD loading. TQD-loaded stearic acid surface-modified HAP (SA-HAP-TQD) was prepared with optimal size and high TQD loading efficiency, and in vitro release and cellular uptake of SA-HAP-TQD showed that SA-HAP-TQD were taken up into lysosome and continuously released TQD from macrophages. In vivo studies have found that over 70 % of SA-HAP was degraded and 80 % of TQD was released from SA-HAP-TQD 28 days after administration. SA-HAP-TQD could increase brain penetration of TMZ, but it would not enhance adverse effects of TMZ in healthy mice. SA-HAP-TQD and TMZ combination had longer median survival than TMZ single therapy in GL261 orthotopic model. These results suggest that SA-HAP-TQD has sustained release characteristics and are potential for improving antitumor effect with TMZ treatment.

Effects of Nanomaterials on Synthesis and Degradation of the Extracellular Matrix

Extracellular matrix (ECM) remodeling is accompanied by the continuous synthesis and degradation of the ECM components. This dynamic process plays an important role in guiding cell adhesion, migration, proliferation, and differentiation, as well as in tissue development, body repair, and maintenance of homeostasis. Nanomaterials, due to their photoelectric and catalytic properties and special structure, have garnered much attention in biomedical fields for use in processes such as tissue engineering and disease treatment. Nanomaterials can reshape the cell microenvironment by changing the synthesis and degradation of ECM-related proteins, thereby indirectly changing the behavior of the surrounding cells. This review focuses on the regulatory role of nanomaterials in the process of cell synthesis of different ECM-related proteins and extracellular protease. We discuss influencing factors and possible related mechanisms of nanomaterials in ECM remodeling, which may provide different insights into the design and development of nanomaterials for the treatment of ECM disorder-related diseases.

A double-network porous hydrogel based on high internal phase emulsions as a vehicle for potassium sucrose octasulfate delivery accelerates diabetic wound healing

Diabetic wounds are a difficult medical challenge. Excessive secretion of matrix metalloproteinase-9 (MMP-9) in diabetic wounds further degrades the extracellular matrix and growth factors and causes severe vascular damage, which seriously hinders diabetic wound healing. To solve these issues, a double-network porous hydrogel composed of poly (methyl methacrylate-co-acrylamide) (p(MMA-co-AM)) and polyvinyl alcohol (PVA) was constructed by the high internal phase emulsion (HIPE) technique for the delivery of potassium sucrose octasulfate (PSO), a drug that can inhibit MMPs, increase angiogenesis and improve microcirculation. The hydrogel possessed a typical polyHIPE hierarchical microstructure with interconnected porous morphologies, high porosity, high specific surface area, excellent mechanical properties and suitable swelling properties. Meanwhile, the p(MMA-co-AM)/PVA@PSO hydrogel showed high drug-loading performance and effective PSO release. In addition, both in vitro and in vivo studies showed that the p(MMA-co-AM)/PVA@PSO hydrogel had good biocompatibility and significantly accelerated diabetic wound healing by inhibiting excessive MMP-9 in diabetic wounds, increasing growth factor secretion, improving vascularization, increasing collagen deposition and promoting re-epithelialization. Therefore, this study provided a reliable therapeutic strategy for diabetic wound healing, some theoretical basis and new insights for the rational design and preparation of wound hydrogel dressings with high porosity, high drug-loading performance and excellent mechanical properties.

Octanoyl esterification of low molecular weight sulfated galactan enhances the cellular uptake and collagen expression in fibroblast cells

Low molecular weight sulfated galactan (LMSG) supplemented with octanoyl ester (Oct-LMSG) demonstrated superior wound healing activity compared to the unsupplemented LMSG in a fibroblast wound model. To test the hypothesis that the increased bioactivity of Oct-LMSG may depend on its penetration into the plasma membrane, its cellular uptake was investigated and collagen production in fibroblast cells was assessed for the first time. The cellular uptake of Oct-LMSG was examined using indirect immunofluorescence and a confocal laser scanning microscope. In addition, the degree of fibroblast activation associated with this uptake was evaluated. The results indicated increased LMSG internalization in fibroblasts treated with Oct-LMSG. Transmission electron micrographs revealed the ultrastructure of active protein production in fibroblasts upon treatment with Oct-LMSG. In addition, Oct-LMSG upregulated the expression of type I collagen mRNA and proteins, as well as related signaling molecules involved in collagen synthesis, including collagen type I α1 chain (Col1A1), Col1A2, phosphorylated (p)-Smad2/3 and p-Smad4. The current findings support the notion that the supplementation of LMSG with octanoyl enhanced its cellular uptake into fibroblasts and, as a result, regulated the expression of type I collagen in fibroblasts via the activation of the Smad signaling pathway. This study demonstrates the therapeutic potential of Oct-LMSG in promoting tissue regeneration.

Collagen architecture and signaling orchestrate cancer development

The tumor microenvironment (TME) controls tumor progression and maintenance. Accordingly, tumor-centric cancer treatment must adjust to being more holistic and TME-centric. Collagens are the most abundant TME proteins, and their dynamic remodeling profoundly affects both TME architecture and tumor development. Recent evidence shows that in addition to being structural elements, collagens are an important source of nutrients and decisive growth controlling and immunoregulatory signals. This review focuses on macropinocytosis-dependent collagen support of cancer cell metabolism and the role of collagen fiber remodeling and trimer heterogeneity in control of tumor bioenergetics, growth, progression, and response to therapy. If properly translated, these basic advances may alter the future of cancer treatment.

Potentilloside A, a New Flavonol-bis-Glucuronide from the Leaves of Potentilla chinensis, Inhibits TNF-α-Induced ROS Generation and MMP-1 Secretion

The major contributor to skin aging is UV radiation, which activates pro-inflammatory cytokines including TNF-α. TNF-α is involved in the acceleration of skin aging via ROS generation and MMP-1 secretion. In our preliminary study, a 30% EtOH extract from the leaves of Potentilla chinensis (LPCE) significantly inhibited TNF-α-induced ROS generation in human dermal fibroblasts (HDFs). Therefore, the objective of this study is to identify the active components in LPCE. A new flavonol-bis-glucuronide (potentilloside A, 1) and 14 known compounds (2-15) were isolated from an LPCE by repeated chromatography. The chemical structure of the new compound 1 was determined by analyzing its spectroscopic data (NMR and HRMS) and by acidic hydrolysis. Nine flavonols (2-9 and 11) and two flavone glycosides (12 and 13) from P. chinensis were reported for the first time in this study. Next, we evaluated the effects of the isolates (1-15) on TNF-α-induced ROS generation in HDFs. As a result, all compounds significantly inhibited ROS generation. Furthermore, LPCE and potentilloside A (1) remarkably suppressed MMP-1 secretion in HDFs stimulated by TNF-α. The data suggested that LPCE and potentilloside A (1) are worthy of further experiments for their potential as anti-skin aging agents.

An update on hydroxyapatite/collagen composites: What is there left to say about these bioinspired materials?

Hydroxyapatite (HAp)/collagen-based composite materials have been a constant in the development of bioinspired materials for bone tissue engineering. The most fundamental research works focus on combining HAp, due to its chemical similarity with the mineral component of bones, and collagen, which is the most abundant protein in the body. Modern studies have explored different two-dimensional (2D) and 3D structures, in order to obtain biomaterials with specific physicochemical, mechanical, and biological characteristics that can be applied in distinct biomedical applications. However, as there is already so much work developed with these materials, it is crucial to question: what can still be done? What is the importance of current know-how for the future of bioinspired materials? In this paper we intend to review and update the available methodologies to synthesize HAp/collagen composites, along with their characteristics. In addition, the future of these materials in terms of applications and their potential as a cutting-edge technology is discussed.

One-Step Synthesis of Magnetic Nanocomposite with Embedded Biologically Active Substance

Magnetic nanocomposites based on hydroxyapatite were prepared by a one-step process using the hydrothermal coprecipitation method to sinter iron oxides (Fe3O4 and γ-Fe2O3). The possibility of expanding the proposed technique for the synthesis of magnetic composite with embedded biologically active substance (BAS) of the 2-arylaminopyrimidine group was shown. The composition, morphology, structural features, and magnetic characteristics of the nanocomposites synthesized with and without BAS were studied. The introduction of BAS into the composite synthesis resulted in minor changes in the structural and physical properties. The specificity of the chemical bonds between BAS and the hydroxyapatite-magnetite core was revealed. The kinetics of the BAS release in a solution simulating the stomach environment was studied. The cytotoxicity of (HAP)FexOy and (HAP)FexOy + BAS composites was studied in vitro using the primary culture of human liver carcinoma cells HepG2. The synthesized magnetic composites with BAS have a high potential for use in the biomedical field, for example, as carriers for magnetically controlled drug delivery and materials for bone tissue engineering.