FoxO3 Regulates Mouse Bone Mesenchymal Stem Cell Fate and Bone-Fat Balance During Skeletal Aging.

Age-related osteoporosis is characterized by an imbalance between osteogenic and adipogenic differentiation in bone mesenchymal stem cells (BMSCs). Forkhead box O 3 (FoxO3) transcription factor is involved in lifespan and cell differentiation. In this study, we explore whether FoxO3 regulates age-related bone loss and marrow fat accumulation. The expression levels of FoxO3 in BMSCs during aging were detected in vivo and in vitro. To explore the role of FoxO3 in osteogenic and adipogenic differentiation, primary BMSCs were isolated from young and aged mice. FoxO3 expression was modulated by adenoviral vector transfection. The role of FoxO3 in bone-fat balance was evaluated by alizarin red S staining, oil red O staining, quantitative reverse transcription-polymerase chain reaction, Western blot, and histological analysis. Age-related bone loss and fat deposit are associated with downregulation of FoxO3. Overexpression of FoxO3 alleviated age-related bone loss and marrow fat accumulation in aged mice. Mechanistically, FoxO3 reduced adipogenesis and enhanced osteogenesis of BMSCs via downregulation of PPAR-γ and Notch signaling, respectively. In conclusion, FoxO3 is an essential factor controlling the fate of BMSCs and is a potential target for the prevention of age-related osteoporosis.

A Bionic Thermosensitive Sustainable Delivery System for Reversing the Progression of Osteoarthritis by Remodeling the Joint Homeostasis.

Although the pathogenesis of osteoarthritis (OA) is unclear, inflammatory cytokines are related to its occurrence. However, few studies focused on the therapeutic strategies of regulating joint homeostasis by simultaneously remodeling the anti-inflammatory and immunomodulatory microenvironments. Fibroblast growth factor 18 (FGF18) is the only disease-modifying OA drug (DMOAD) with a potent ability and high efficiency in maintaining the phenotype of chondrocytes within cell culture models. However, its potential role in the immune microenvironment remains unknown. Besides, information on an optimal carrier, whose interface and chondral-biomimetic microenvironment mimic the native articular tissue, is still lacking, which substantially limits the clinical efficacy of FGF18. Herein, to simulate the cartilage matrix, chondroitin sulfate (ChS)-based nanoparticles (NPs) are integrated into poly(D, L-lactide)-poly(ethylene glycol)-poly(D, L-lactide) (PLEL) hydrogels to develop a bionic thermosensitive sustainable delivery system. Electrostatically self-assembled ChS and ε-poly-l-lysine (EPL) NPs are prepared for the bioencapsulation of FGF18. This bionic delivery system suppressed the inflammatory response in interleukin-1ß (IL-1ß)-mediated chondrocytes, promoted macrophage M2 polarization, and inhibited M1 polarization, thereby ameliorating cartilage degeneration and synovitis in OA. Thus, the ChS-based hydrogel system offers a potential strategy to regulate the chondrocyte-macrophage crosstalk, thus re-establishing the anti-inflammatory and immunomodulatory microenvironment for OA therapy.

Sustained Release of Dicumarol via Novel Grafted Polymer in Electrospun Nanofiber Membrane for Treatment of Peritendinous Adhesion.

The prevention and treatment of post-traumatic peritendinous adhesion (PA) have always been a great difficulty for orthopedic surgeons. Current treatments include resecting surgery, non-steroidal anti-inflammatory drugs (NSAIDs) usage and implantable membranes, often target single disease pathogenic processes, resulting in unfavorable therapeutic outcomes. Here a polylactic acid (PLA)-dicumarol conjugates-electrospun nanofiber membrane (ENM) (PCD) is generated, which can achieve spatial accuracy and temporal sustainability in drug release. It is further demonstrated that PCD possesses a significantly higher and more sustainable drug release profile than traditional drug-loading ENM. By providing a physical barrier and continuous releasing of dicumarol, PCD implantation significantly reduces tissue adhesion by 25%, decreases fibroblasts activity and inhibits key fibrogenic cytokine transforming growth factor beta (TGFß) production by 30%, and improves the biomechanical tendon property by 14.69%. Mechanistically, PCD potently inhibits the connexin43 (Cx43) and thereby tunes down the fibroblastic TGFß/Smad3 signaling pathway. Thus, this approach leverages the anti-adhesion effect of dicumarol and drug release properties of grafted copolymer ENM by esters to provide a promising therapeutic strategy for patients who suffer from PA.

Pyrrolidine Dithiocarbamate-loaded Electrospun Membranes for Peritendinous Anti-adhesion through Inhibition of the Nuclear Factor-κB Pathway.

Peritendinous adhesion is a major cause of limb dysfunction and disability in clinical practice. Numerous studies suggest that activation of nuclear factor-κB (NF-κB) pathway in macrophages could be the pivotal figure in excessive collagen synthesis and thus peritendinous adhesion formation. In this study, we assumed this pathological process could be suppressed by inhibiting NF-κB phosphorylation and nuclear translocation using pyrrolidine dithiocarbamate (PDTC), a specific NF-κB inhibitor with the ability to penetrate cell membranes, in macrophages. Then, we conducted electrospinning process to incorporate PDTC into poly(L-lactic) acid (PLA) electrospinning membranes, that is, the PDTC-PLA membranes. Further, with integral film quality and stable drug release property, the PDTC-PLA membranes were subsequently analyzed in the capability and mechanism of preventing adhesion formation both in vitro and in vivo. Our results showed inhibition of macrophage proliferation as well as NF-κB pathway activation from in vitro assays and outstanding promotion in inhibiting NF-κB p65 phosphorylation and reducing adhesion formation from in vivo assays of PDTC-PLA compared to PLA membranes. In conclusion, our findings suggested that PDTC-PLA as an alternative therapeutic approach alleviated inflammation and peritendinous adhesion formation through NF-κB signaling pathway. STATEMENT OF SIGNIFICANCE: Pyrrolidine dithiocarbamate (PDTC) can be blended into poly-L-lactic acid (PLA) fibrous membranes by electrospinning process. This incorporation of PDTC into PLA is an effective way to inhibit proinflammatory activation of macrophages and to achieve advanced anti-adhesion outcome after tendon repair.

Self-Healing Hydrogel Embodied with Macrophage-Regulation and Responsive-Gene-Silencing Properties for Synergistic Prevention of Peritendinous Adhesion.

Antiadhesion barriers such as films and hydrogels used to wrap repaired tendons are important for preventing the formation of adhesion tissue after tendon surgery. However, sliding of the tendon can compress the adjacent hydrogel barrier and cause it to rupture, which may then lead to unexpected inflammation. Here, a self-healing and deformable hyaluronic acid (HA) hydrogel is constructed as a peritendinous antiadhesion barrier. Matrix metalloproteinase-2 (MMP-2)-degradable gelatin-methacryloyl (GelMA) microspheres (MSs) encapsulated with Smad3-siRNA nanoparticles are entrapped within the HA hydrogel to inhibit fibroblast proliferation and prevent peritendinous adhesion. GelMA MSs are responsively degraded by upregulation of MMP-2, achieving on-demand release of siRNA nanoparticles. Silencing effect of Smad3-siRNA nanoparticles is around 75% toward targeted gene. Furthermore, the self-healing hydrogel shows relatively attenuated inflammation compared to non-healing hydrogel. The mean adhesion scores of composite barrier group are 1.67 ± 0.51 and 2.17 ± 0.75 by macroscopic and histological evaluation, respectively. The proposed self-healing hydrogel antiadhesion barrier with MMP-2-responsive drug release behavior is highly effective for decreasing inflammation and inhibiting tendon adhesion. Therefore, this research provides a new strategy for the development of safe and effective antiadhesion barriers.

Macrophage Polarization Modulated by NF-κB in Polylactide Membranes-Treated Peritendinous Adhesion.

Foreign body reactions (FBR) to implants seriously impair tissue-implant integration and postoperative adhesion. The macrophage, owing to its phenotypic plasticity, is a major regulator in the formation of the inflammatory microenvironment; NF-κB signaling also plays a vital role in the process. It is hypothesized that NF-κB phosphorylation exerts a proinflammatory regulator in FBR to polylactide membranes (PLA-M) and adhesion. First, in vitro and in vivo experiments show that PLA-M induces NF-κB phosphorylation in macrophages, leading to M1 polarization and release of inflammatory factors. The inflammatory microenvironment formed due to PLA-M accelerates myofibroblast differentiation and release of collagen III and MMP2, jointly resulting in peritendinous adhesion. Therefore, JSH-23 (a selective NF-κB inhibitor)-loaded PLA membrane (JSH-23/PLA-M) is fabricated by blend electrospinning to regulate the associated M1 polarization for peritendinous anti-adhesion. JSH-23/PLA-M specifically inhibits NF-κB phosphorylation in macrophages and exhibits anti-inflammatory and anti-adhesion properties. The findings demonstrate that NF-κB phosphorylation has a critical role in PLA-induced M1 polarization and aggravating FBR to PLA-M. Additionally, JSH-23/PLA-M precisely targets modulation of NF-κB phosphorylation in FBR to break the vicious cycle in peritendinous adhesion therapy.

Promotion of collagen deposition during skin healing through Smad3/mTOR pathway by parathyroid hormone-loaded microneedle.

Skin wounds are associated with huge economic and emotional burdens for millions of people annually and are a challenge for health workers worldwide. At present, for skin defects after traumatic accidents, especially large-area skin defects, newly developed strategies such as the use of emerging biomaterials and cell therapy could be considered as options besides classic skin grafts. However, the new strategies have to deal with problems such as immune rejection and high costs for patients. An insufficient understanding of the mechanisms of skin wound healing further hinders the development of innovative treatment approaches. In this study, we developed a parathyroid hormone (PTH)-loaded phase-transition microneedle (PTMN) patch to deliver PTH subcutaneously in an efficient manner and change microneedle patch daily to achieve intermittent and systematic drug administration. By evaluating wound closure, re-epithelialization, collagen deposition, and extracellular matrix (ECM) expression in a Sprague-Dawley rat model of traumatic skin wounds, we demonstrated that intermittent systemic administration of PTH using our PTMN patches accelerated skin wound healing. Further, we demonstrated that the use of the patch may accelerate skin wound healing depending on the activation of the transforming growth factor (TGF)-ß/Smad3/mammalian target of rapamycin (mTOR) cascade pathway. Our results suggest that the PTH-loaded PTMN patch may be a novel therapeutic strategy for treating skin wounds.

Beeswax-inspired superhydrophobic electrospun membranes for peritendinous anti-adhesion.

Posttraumatic peritendinous adhesion leads to limb disability. Physical barrier was widely used and thus focus was paid to fabricate the hydrophobic surfaces of electrospun membrane for anti-adhesion. However, current methods are limited and complicated. In this study, beeswax (Wax)/poly-L-lactic acid (PLA) anti-adhesion membranes were fabricated by blending electrospinning of Wax and PLA. The water contact angle was tested to investigate the hydrophobicity of the surfaces. Incorporation of Wax into PLA did not destroy the micro-pores between Wax/PLA fibers. After 7-day culture, proliferation of fibroblasts on Wax/PLA anti-adhesion membranes were significantly less than that on culture dish and PLA membranes. In rat Achilles adhesion model, least histological peritendinous adhesion formation was detected on the repaired sites in the group treated with Wax/PLA membranes than PLA membranes. Consequently, blending electrospinning of Wax into PLA is an easy method to fabricate hydrophobic surface of electrospun membrane with advanced peritendinous anti-adhesion outcome.