Layer-by-layer assembly of procyanidin and collagen promotes mesenchymal stem cell proliferation and osteogenic differentiation in vitro and in vivo

Immobilizing c(RGDfc) on the surface of metal-phenolic networks by thiol-click reaction for accelerating osteointegration of implant

The limited osteointegration often leads to the failure of implant, which can be improved by fixing bioactive molecules onto the surface, such as arginyl-glycyl-aspartic acid (RGD): a cell adhesion motif. Metal-Phenolic Networks (MPNs) have garnered increasing attention from different disciplines in recent years due to their simple and rapid process for depositing on various substrates or particles with different shapes. However, the lack of cellular binding sites on MPNs greatly blocks its application in tissue engineering. In this study, we present a facile and efficient approach for producing PC/Fe@c(RGDfc) composite coatings through the conjugation of c(RGDfc) peptides onto the surface of PC/Fe-MPNs utilizing thiol-click reaction. By combined various techniques (ellipsometry, X-ray photoelectron spectroscopy, Liquid Chromatography-Mass Spectrometry, water contact angle, scanning electronic microscopy, atomic force microscopy) the physicochemical properties (composition, coating mechanism and process, modulus and hydrophilicity) of PC/Fe@c(RGDfc) surface were characterized in detail. In addition, the PC/Fe@c(RGDfc) coating exhibits the remarkable ability to positively modulate cellular attachment, proliferation, migration and promoted bone-implant integration in vivo, maintaining the inherent features of MPNs: anti-inflammatory, anti-oxidative properties, as well as multiple substrate deposition. This work contributes to engineering MPNs-based coatings with bioactive molecules by a facile and efficient thiol-click reaction, as an innovative perspective for future development of surface modification of implant materials.

Implants coating strategies for antibacterial treatment in fracture and defect models: A systematic review of animal studies

Objective

Fracture-related infection (FRI) remains a major concern in orthopaedic trauma. Functionalizing implants with antibacterial coatings are a promising strategy in mitigating FRI. Numerous implant coatings have been reported but the preventive and therapeutic effects vary. This systematic review aimed to provide a comprehensive overview of current implant coating strategies to prevent and treat FRI in animal fracture and bone defect models.

Methods

A literature search was performed in three databases: PubMed, Web of Science and Embase, with predetermined keywords and criteria up to 28 February 2023. Preclinical studies on implant coatings in animal fracture or defect models that assessed antibacterial and bone healing effects were included.

Results

A total of 14 studies were included in this systematic review, seven of which used fracture models and seven used defect models. Passive coatings with bacteria adhesion resistance were investigated in two studies. Active coatings with bactericidal effects were investigated in 12 studies, four of which used metal ions including Ag+ and Cu2+; five studies used antibiotics including chlorhexidine, tigecycline, vancomycin, and gentamicin sulfate; and the other three studies used natural antibacterial materials including chitosan, antimicrobial peptides, and lysostaphin. Overall, these implant coatings exhibited promising efficacy in antibacterial effects and bone formation.

Conclusion

Antibacterial coating strategies reduced bacterial infections in animal models and favored bone healing in vivo. Future studies of implant coatings should focus on optimal biocompatibility, antibacterial effects against multi-drug resistant bacteria and polymicrobial infections, and osseointegration and osteogenesis promotion especially in osteoporotic bone by constructing multi-functional coatings for FRI therapy.

The translational potential of this paper

The clinical treatment of FRI is complex and challenging. This review summarizes novel orthopaedic implant coating strategies applied to FRI in preclinical studies, and offers a perspective on the future development of orthopaedic implant coatings, which can potentially contribute to alternative strategies in clinical practice.

Engineering tunable dual peptide hybrid coatings promote osseointegration of implants

Utilizing complementary bioactive peptides is a promising surface engineering strategy for bone regeneration on osteogenesis. In this study, we designed block peptides, (Lysine)6-capped RGD (K6-(linker-RGD)3) and OGP (K6-linker-(YGFGG)2), which were mildly grafted onto PC/Fe-MPNs through supramolecular interactions between K6 and PC residues on the MPNs surface to form a dual peptide coating, named PC/Fe@K6-RGD/OGP. The properties of the block peptides coating, including mechanics, hydrophilicity, chemical composition, etc., were detailly characterized by various techniques (ellipsometry, quartz crystal microbalance, X-ray photoelectron spectroscopy, water contact angle, scanning electronic microscopy and atomic force microscopy). Importantly, the RGD/OGP ratio can be well adjusted, which allowed optimizing the RGD/OGP ratio to endow significantly enhanced osteogenic activity of MC3T3-E1 cells through the Wnt/β-catenin pathway, while also promoting cell adhesion, immune regulation, inhibiting osteoclast differentiation and oxidative stress reduction. In vivo, the optimized RGD/OGP coatings promoted bone regeneration and osseointegration around implants in rats with bone defects. In conclusion, rationally designed PC/Fe@K6-RGD/OGP coating integrated RGD and OGP bioactivities, providing a convenient approach to enhance bioinert implant surfaces for bone regeneration.

Immediate implantation of ultrafine fiber slow-release system based on cell electrospinning to induce osteogenesis of mesenchymal stem cells

This study presents the development and evaluation of a poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) ultrafine fiber slow-release system for in vivo osteogenic induction of human umbilical cord mesenchymal stem cells (HUCMSCs). Utilizing dual-nozzle and cell electrospinning techniques, the system encapsulates L-ascorbic acid-2-phosphate magnesium (ASP), β-glycerophosphate sodium and dexamethasone (DEX) within the fibers, ensuring sustained osteogenic differentiation. The scaffold's morphology, characterization, hydrophilicity, mechanical properties and cellular behavior were examined. Immediate subcutaneous implantation in rabbits was conducted to observe its ectopic osteogenic induction effect. Successfully fabricated P34HB ultrafine fiber slow-release system. Characterization confirmed the uniform distribution of HUCMSCs and inducing components within the scaffold, with no chemical reactions affecting the active components. In vitro tests showcased a prolonged release of DEX and ASP, while biocompatibility assays highlighted the scaffold's suitability for cellular growth. Alizarin Red, type I collagen, and osteopontin (OPN) staining verified the scaffold's potent osteogenic induction effect on HUCMSCs. Notably, immediate implantation into New Zealand White rabbits led to significant new bone formation within 8 weeks. These findings underscore the system's potential for immediate in vivo implantation without prior in vitro induction, marking a promising advancement in bone tissue engineering.

Fibrous topology promoted pBMP2-activated matrix on titanium implants boost osseointegration

Titanium (Ti) implants have been extensively used after surgical operations. Its surface bioactivity is of importance to facilitate integration with surrounding bone tissue, and ultimately ensure stability and long-term functionality of the implant. The plasmid DNA-activated matrix (DAM) coating on the surface could benefit osseointegration but is still trapped by poor transfection for further application, especially on the bone marrow mesenchymal stem cells (BMSCs) in vivo practical conditions. Herein, we constructed a DAM on the surface of fibrous-grained titanium (FG Ti) composed of phase-transition lysozyme (P) as adhesive, cationic arginine-rich lipid (RLS) as the transfection agent and plasmid DNA (pDNA) for bone morphology protein 2 (BMP2) expression. The cationic lipid RLS improved up to 30-fold higher transfection than that of commercial reagents (Lipofectamine 2000 and polyethyleneimine) on MSC. And importantly, Ti surface topology not only promotes the DAM to achieve high transfection efficiency (∼75.7% positive cells) on MSC due to the favorable combination but also reserves its contact induction effect for osteoblasts. Upon further exploration, the fibrous topology on FG Ti could boost pDNA uptake for gene transfection, and cell migration in MSC through cytoskeleton remodeling and induce contact guidance for enhanced osteointegration. At the same time, the cationic RLS together with adhesive P were both antibacterial, showing up to 90% inhibition rate against Escherichia coli and Staphylococcus aureus with reduced adherent microorganisms and disrupted bacteria. Finally, the FG Ti-P/pBMP2 implant achieved accelerated bone healing capacities through highly efficient gene delivery, aligned surface topological structure and increased antimicrobial properties in a rat femoral condylar defect model.

[Effect of Wnt/β-catenin signaling pathway in neural differentiation of human bone marrow mesenchymal stem cells]

Objective

To explore the effect of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and the combination of bFGF and EGF in the neural differentiation of human bone marrow mesenchymal stem cells (hBMSCs), and the role of Wnt/β-catenin signaling pathway in this process.

Methods

The identified 4th-generation hBMSCs were divided into five groups according to different induction conditions, namely control group (group A), EGF induction group (group B), bFGF induction group (group C), EGF and bFGF combined induction group (group D), and EGF, bFGF, and Dickkopf-related protein 1 (DKK-1) combined induction group (group E). After 7 days of continuous induction, the cell morphology was observed by inverted fluorescence phase contrast microscopy, levels of genes that were related to neural cells [Nestin, neuron-specific enolase (NSE), microtubule-associated protein 2 (MAP-2), and glial fibrillary acidic protein (GFAP)] and key components of the Wnt/β-catenin signaling pathway (β-catenin and Cyclin D1) were detected by RT-PCR, and the levels of proteins that were related to neural cells (Nestin and GFAP) as well as genes that were involved in Wnt/β-catenin signaling pathway [β-catenin, phosphorylation β-catenin (P-β-catenin), Cytoplasmic β-catenin, and Nuclear β-catenin] were explored by cellular immunofluorescence staining and Western blot.

Results

When compared to groups A and B, the typical neuro-like cell changes were observed in groups C-E, and most obviously in group D. RT-PCR showed that the relative expressions of Nestin, NSE, and MAP-2 genes in groups C-E, the relative expressions of GFAP gene in groups D and E, the relative expression of NSE gene in group B, the relative expressions of β-catenin gene in groups C and D, and the relative expressions of Cyclin D1 gene in groups B-D significantly increased when compared with group A ( P<0.05). Compared with group E, the relative expressions of Nestin, NSE, MAP-2, GFAP, β-catenin, and CyclinD1 genes significantly increased in group D ( P<0.05); compared with group C, the relative expression of Nestin gene in group D significantly decreased ( P<0.05), while NSE, MAP-2, and GFAP genes significantly increased ( P<0.05). The cellular immunofluorescence staining showed that the ratio of NSE- and GFAP-positive cells significantly increased in groups C-E than in group A, in group D than in groups C and E ( P<0.05). Western blot assay showed that the relative expression of NSE protein was significantly higher in groups C and D than in group A and in group D than in groups C and E ( P<0.05). In addition, the relative expression of GFAP protein was significantly higher in groups C-E than in group A and in group D than in group E ( P<0.05). Besides, the relative expressions of β-catenin, Cytoplasmic β-catenin, Nuclear β-catenin, and the ratio of Nuclear β-catenin to Cytoplasmic β-catenin were significantly higher in groups C and D than in group A and in group D than in group E ( P<0.05), whereas the relative expression of P-β-catenin protein was significantly lower in groups C and D than in group A and in group D than in group E ( P<0.05).

Conclusion

Different from EGF, bFGF can induce neural differentiation of hBMSCs. In addition, EGF can enhance the hBMSCs neural differentiation of bFGF, while the Wnt/β-catenin signaling pathway may play a positive regulatory role in these processes.

A construct of adipose-derived mesenchymal stem cells-laden collagen scaffold for fertility restoration by inhibiting fibrosis in a rat model of endometrial injury

Severe endometrium damage causes pathological conditions such as thin endometrium and intrauterine adhesion, resulting in uterine factor infertility. Mesenchymal stem cell (MSC) therapy is a promising strategy in endometrial repair; yet, exogenous MSCs still raise concerns for safety and ethical issues. Human adipose-derived mesenchymal stem cells (ADMSCs) residing in adipose tissue have high translational potentials due to their autologous origin. To harness the high translation potentials of ADMSC in clinical endometrium regeneration, here we constructed an ADMSCs composited porous scaffold (CS/ADMSC) and evaluated its effectiveness on endometrial regeneration in a rat endometrium-injury model. We found that CS/ADMSC intrauterine implantation (i) promoted endometrial thickness and gland number, (ii) enhanced tissue angiogenesis, (iii) reduced fibrosis and (iv) restored fertility. We ascertained the pro-proliferation, pro-angiogenesis, immunomodulating and anti-fibrotic effects of CS/ADMSC in vitro and revealed that the CS/ADMSC influenced extracellular matrix composition and organization by a transcriptomic analysis. Our results demonstrated the effectiveness of CS/ADMSC for endometrial regeneration and provided solid proof for our future clinical study.

Engineering Antioxidant Surfaces for Titanium-Based Metallic Biomaterials

Prolonged inflammation induced by orthopedic metallic implants can critically affect the success rates, which can even lead to aseptic loosening and consequent implant failure. In the case of adverse clinical conditions involving osteoporosis, orthopedic trauma and implant corrosion-wear in peri-implant region, the reactive oxygen species (ROS) activity is enhanced which leads to increased oxidative stress. Metallic implant materials (such as titanium and its alloys) can induce increased amount of ROS, thereby critically influencing the healing process. This will consequently affect the bone remodeling process and increase healing time. The current review explores the ROS generation aspects associated with Ti-based metallic biomaterials and the various surface modification strategies developed specifically to improve antioxidant aspects of Ti surfaces. The initial part of this review explores the ROS generation associated with Ti implant materials and the associated ROS metabolism resulting in the formation of superoxide anion, hydroxyl radical and hydrogen peroxide radicals. This is followed by a comprehensive overview of various organic and inorganic coatings/materials for effective antioxidant surfaces and outlook in this research direction. Overall, this review highlights the critical need to consider the aspects of ROS generation as well as oxidative stress while designing an implant material and its effective surface engineering.