Multiple integrin ligands provide a highly adhesive and osteoinductive surface that improves selective cell retention technology

A Functionalized Scaffold Facilitates Neurites Extension for Spinal Cord Injury Therapy

Scaffolds have garnered considerable attention for enhancing neural repairment for spinal cord injury (SCI) treatment. Both microstructural features and biochemical modifications play pivotal roles in influencing the interaction of cells with the scaffold, thereby affecting tissue regeneration. Here, a scaffold is designed with spiral structure and gradient peptide modification (GS) specifically for SCI treatment. The spiral structure provides crucial support and space, while the gradient peptide isoleucine-lysine-valine-alanine-valine (IKVAV) modification imparts directional guidance for neuronal and axonal extension. GS scaffold shows a significant nerve extension induction effect through its interlayer gap and gradient peptide density to dorsal root ganglia in vitro, while in vivo studies reveal its substantial promotion for functional recovery and neural repair. Additionally, the GS scaffold displays impressive drug-loading capacity, mesenchymal stem cell-derived exosomes can be efficiently loaded into the GS scaffold and delivered to the injury site, thereby synergistically promoting SCI repair. Overall, the GS scaffold can serve as a versatile platform and present a promising multifunctional approach for SCI treatment.

Exploring a Solvent Dependent Strategy to Control Self-Assembling Behavior and Cellular Interaction in Laminin-Mimetic Short Peptide based Supramolecular Hydrogels

Self-assembled hydrogels, fabricated through diverse non-covalent interactions, have been extensively studied in regenerative medicines. Inspired from bioactive functional motifs of ECM protein, short peptide sequences have shown remarkable abilities to replicate the intrinsic features of the natural extracellular milieu. In this direction, we have fabricated two short hydrophobic bioactive sequences derived from the laminin protein i. e., IKVAV and YIGSR. Based on the substantial hydrophobicity of these peptides, we selected a co-solvent approach as a suitable gelation technique that included different concentrations of DMSO as an organic phase along with an aqueous solution containing 0.1 % TFA. These hydrophobic laminin-based bioactive peptides with limited solubility in aqueous physiological environment showed significantly enhanced solubility with higher DMSO content in water. The enhanced solubility resulted in extensive intermolecular interactions that led to the formation of hydrogels with a higher-order entangled network along with improved mechanical properties. Interestingly, by simply modulating DMSO content, highly tunable gels were accessed in the same gelator domain that displayed differential physicochemical properties. Further, the cellular studies substantiated the potential of these laminin-derived hydrogels in enhancing cell-matrix interactions, thereby reinforcing their applications in tissue engineering.

Advancements in the pathogenesis of hepatic osteodystrophy and the potential therapeutic of mesenchymal stromal cells

Hepatic osteodystrophy (HOD) is a metabolically associated bone disease mainly manifested as osteoporosis with the characteristic of bone loss induced by chronic liver disease (CLD). Due to its high incidence in CLD patients and increased risk of fracture, the research on HOD has received considerable interest. The specific pathogenesis of HOD has not been fully revealed. While it is widely believed that disturbance of hormone level, abnormal secretion of cytokines and damage of intestinal barrier caused by CLD might jointly affect the bone metabolic balance of bone formation and bone absorption. At present, the treatment of HOD is mainly to alleviate the bone loss by drug treatment, but the efficacy and safety are not satisfactory. Mesenchymal stromal cells (MSCs) are cells with multidirectional differentiation potential, cell transplantation therapy based on MSCs is an emerging therapeutic approach. This review mainly summarized the pathogenesis and treatment of HOD, reviewed the research progress of MSCs therapy and the combination of MSCs and scaffolds in the application of osteoporotic bone defects, and discussed the potential and limitations of MSCs therapy, providing theoretical basis for subsequent studies.

The Role of Integrin Receptor's α and β Subunits of Mouse Mesenchymal Stem Cells on the Interaction of Marine-Derived Blacktip Reef Shark (Carcharhinus melanopterus) Skin Collagen

Marine collagen (MC) has recently attracted more attention in tissue engineering as a biomaterial substitute due to its significant role in cellular signaling mechanisms, especially in mesenchymal stem cells (MSCs). However, the actual signaling mechanism of MC in MSC growth, which is highly influenced by their molecular pattern, is poorly understood. Hence, we investigated the integrin receptors (α₁β₁, α₂β₁, α₁₀β₁, and α₁₁β₁) binding mechanism and proliferation of MCs (blacktip reef shark collagen (BSC) and blue shark collagen (SC)) compared to bovine collagen (BC) on MSCs behavior through functionalized collagen molecule probing for the first time. The results showed that BSC and SC had higher proliferation rates and accelerated scratch wound healing by increasing migratory rates of MSCs. Cell adhesion and spreading results demonstrated that MC had a better capacity to anchor MSCs and maintain cell morphology than controls. Living cell observations showed that BSC was gradually assembled by cells into the ECM network within 24 h. Interestingly, qRT-PCR and ELISA revealed that the proliferative effect of MC was triggered by interacting with specific integrin receptors such as α₂β₁, α₁₀β₁, and α₁₁β₁ of MSCs. Accordingly, BSC accelerated MSCs' growth, adhesion, shape, and spreading by interacting with specific integrin subunits (α₂ and β₁) and thereby triggering further signaling cascade mechanisms.

Intraoperative Creation of Tissue-Engineered Grafts with Minimally Manipulated Cells: New Concept of Bone Tissue Engineering In Situ

Transfer of regenerative approaches into clinical practice is limited by strict legal regulation of in vitro expanded cells and risks associated with substantial manipulations. Isolation of cells for the enrichment of bone grafts directly in the Operating Room appears to be a promising solution for the translation of biomedical technologies into clinical practice. These intraoperative approaches could be generally characterized as a joint concept of tissue engineering in situ. Our review covers techniques of intraoperative cell isolation and seeding for the creation of tissue-engineered grafts in situ, that is, directly in the Operating Room. Up-to-date, the clinical use of tissue-engineered grafts created in vitro remains a highly inaccessible option. Fortunately, intraoperative tissue engineering in situ is already available for patients who need advanced treatment modalities.

Bioactive Scaffold Fabricated by 3D Printing for Enhancing Osteoporotic Bone Regeneration

We develop a poly (lactic-co-glycolic acid)/β-calcium phosphate (PLGA/TCP)-based scaffold through a three-dimensional (3D) printing technique incorporating icaritin (ICT), a unique phytomolecule, and secretome derived from human fetal mesenchymal stem cells (HFS), to provide mechanical support and biological cues for stimulating bone defect healing. With the sustained release of ICT and HFS from the composite scaffold, the cell-free scaffold efficiently facilitates the migration of MSCs and promotes bone regeneration at the femoral defect site in the ovariectomy (OVX)-induced osteoporotic rat model. Furthermore, mechanism study results indicate that the combination of ICT and HFS additively activates the Integrin-FAK (focal adhesion kinase)-ERK1/2 (extracellular signal-regulated kinase 1/2)-Runx2 (Runt-related transcription factor 2) axis, which could be linked to the beneficial recruitment of MSCs to the implant and subsequent osteogenesis enhancement. Collectively, the PLGA/TCP/ICT/HFS (P/T/I/S) bioactive scaffold is a promising biomaterial for repairing osteoporotic bone defects, which may have immense implications for their translation to clinical practice.

Tapping basement membrane motifs: Oral junctional epithelium for surface-mediated soft tissue attachment to prevent failure of percutaneous devices

Teeth, long-lasting percutaneous organs, feature soft tissue attachment through adhesive structures, hemidesmosomes, in the junctional epithelium basement membrane adjacent to teeth. This soft tissue attachment prevents bacterial infection of the tooth despite the rich - and harsh - microbial composition of the oral cavity. Conversely, millions of percutaneous devices (catheters, dental, and orthopedic implants) fail from infection yearly. Standard of care antibiotic usage fuels antimicrobial resistance and is frequently ineffective. Infection prevention strategies, like for dental implants, have failed in generating durable soft tissue adhesion - like that seen with the tooth - to prevent bacterial colonization at the tissue-device interface. Here, inspired by the impervious natural attachment of the junctional epithelium to teeth, we synthesized four cell adhesion peptide (CAPs) nanocoatings, derived from basement membranes, to promote percutaneous device soft tissue attachment. The two leading nanocoatings upregulated integrin-mediated hemidesmosomes, selectively increased keratinocyte proliferation compared to fibroblasts, which cannot form hemidesmosomes, and expression of junctional epithelium adhesive markers. CAP nanocoatings displayed marked durability under simulated clinical conditions and the top performer CAP nanocoating was validated in a percutaneous implant murine model. Basement membrane CAP nanocoatings, inspired by the tooth and junctional epithelium, may provide an alternative anti-infective strategy for percutaneous devices to mitigate the worldwide threat of antimicrobial resistance. STATEMENT OF SIGNIFICANCE: Prevention and management of medical device infection is a significant healthcare challenge. Overzealous antibiotic use has motivated alternative material innovations to prevent infection. Here, we report implant cell adhesion peptide nanocoatings that mimic a long-lasting, natural "medical device," the tooth, through formation of cell adhesive structures called hemidesmosomes. Such nanocoatings sidestep the use of antimicrobial or antibiotic elements to form a soft-tissue seal around implants. The top performing nanocoatings prompted expression of hemidesmosomes and defensive factors to mimic the tooth and was validated in an animal model. Application of cell adhesion peptide nanocoatings may provide an alternative to preventing, rather that necessarily treating, medical device infection across a range of device indications, like dental implants.

Mechanistically Scoping Cell-Free and Cell-Dependent Artificial Scaffolds in Rebuilding Skeletal and Dental Hard Tissues

Rebuilding mineralized tissues in skeletal and dental systems remains costly and challenging. Despite numerous demands and heavy clinical burden over the world, sources of autografts, allografts, and xenografts are far limited, along with massive risks including viral infections, ethic crisis, and so on. Per such dilemma, artificial scaffolds have emerged to provide efficient alternatives. To date, cell-free biomimetic mineralization (BM) and cell-dependent scaffolds have both demonstrated promising capabilities of regenerating mineralized tissues. However, BM and cell-dependent scaffolds have distinctive mechanisms for mineral genesis, which makes them methodically, synthetically, and functionally disparate. Herein, these two strategies in regenerative dentistry and orthopedics are systematically summarized at the level of mechanisms. For BM, methodological and theoretical advances are focused upon; and meanwhile, for cell-dependent scaffolds, it is demonstrated how scaffolds orchestrate osteogenic cell fate. The summary of the experimental advances and clinical progress will endow researchers with mechanistic understandings of artificial scaffolds in rebuilding hard tissues, by which better clinical choices and research directions may be approached.

Superparamagnetic core-shell electrospun scaffolds with sustained release of IONPs facilitating in vitro and in vivo bone regeneration

Bone tissue engineering (BTE) is a promising approach to recover insufficient bone in dental implantations. However, the clinical application of BTE scaffolds is limited by their low mechanical strength and lack of osteoinduction. In an attempt to circumvent these limitations and improve osteogenesis, we introduced magnetic iron oxide nanoparticles (IONPs) into a core-shell porous electrospun scaffold and evaluated their impact on the physical, mechanical, and biological properties of the scaffold. We used poly(lactic-co-glycolic acid)/polycaprolactone/beta-tricalcium phosphate (PPT) scaffolds with and without γ-Fe₂O₃ encapsulation, namely PPT-Fe scaffolds and PPT scaffolds, respectively. The γ-Fe₂O₃ used in the PPT-Fe scaffolds was coated with polyglucose sorbitol carboxymethylether and was biocompatible. Structurally, PPT-Fe scaffolds showed uniform iron distribution encapsulated within the resorbable PPT scaffolds, and these scaffolds supported sustainable iron release. Furthermore, compared with PPT scaffolds, PPT-Fe scaffolds showed significantly better physical and mechanical properties, including wettability, superparamagnetism, hardness, tensile strength, and elasticity modulus. In vitro tests of rat adipose-derived mesenchymal stem cells (rADSCs) seeded onto the scaffolds showed increased expression of integrin β1, alkaline phosphatase, and osteogenesis-related genes. In addition, enhanced in vivo bone regeneration was observed after implanting PPT-Fe scaffolds in rat calvarial bone defects. Thus, we can conclude that the incorporation of IONPs into porous scaffolds for long-term release can provide a new strategy for BTE scaffold optimization and is a promising approach that can offer enhanced osteogenic capacity in clinical applications.

Cutting Edge Endogenous Promoting and Exogenous Driven Strategies for Bone Regeneration

Bone damage leading to bone loss can arise from a wide range of causes, including those intrinsic to individuals such as infections or diseases with metabolic (diabetes), genetic (osteogenesis imperfecta), and/or age-related (osteoporosis) etiology, or extrinsic ones coming from external insults such as trauma or surgery. Although bone tissue has an intrinsic capacity of self-repair, large bone defects often require anabolic treatments targeting bone formation process and/or bone grafts, aiming to restore bone loss. The current bone surrogates used for clinical purposes are autologous, allogeneic, or xenogeneic bone grafts, which although effective imply a number of limitations: the need to remove bone from another location in the case of autologous transplants and the possibility of an immune rejection when using allogeneic or xenogeneic grafts. To overcome these limitations, cutting edge therapies for skeletal regeneration of bone defects are currently under extensive research with promising results; such as those boosting endogenous bone regeneration, by the stimulation of host cells, or the ones driven exogenously with scaffolds, biomolecules, and mesenchymal stem cells as key players of bone healing process.

Laminin alpha 4 promotes bone regeneration by facilitating cell adhesion and vascularization

Selective cell retention (SCR) has been widely used as a bone tissue engineering technique for the real-time fabrication of bone grafts. The greater the number of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) retained in the scaffold, the better the osteoinductive and angiogenic properties of the scaffold's microenvironment. Improved bioscaffold properties in turn lead to improved bone graft survival, bone regeneration, and angiogenesis. Laminin plays a key role in cell-matrix adhesion, cell proliferation, and differentiation. We designed a collagen-binding domain (CBD) containing the core functional amino acid sequences of laminin α4 (CBD-LN peptide) to supplement the functional surface of a collagen-based decalcified bone matrix (DBM) scaffold. This scaffold promoted MSCs and EPCs early cell adhesion through up-regulating the expression of integrin α5β1 and integrin αvβ3 respectively, thus accelerated the following cell spreading, proliferation, and differentiation. Interestingly, it promoted the retention of MSCs (CD90⁺/CD105⁺ cells) and EPCs (CD31⁺ cells) in the scaffold following the use of clinical SCR technology. Furthermore, the DBM/CBD-LN scaffold induced the formation of type H vessels through the activation of the HIF-1α signaling pathway. The DBM/CBD-LN scaffold displayed rapid bone formation and angiogenesis in vivo, suggesting that it might be used as a new biomaterial in bone tissue engineering. STATEMENT OF SIGNIFICANCE: Selective cell retention technology (SCR) has been utilized in clinical settings to manufacture bioactive bone grafts. Specifically, demineralized bone matrix (DBM) is a widely-used SCR clinical biomaterial but it displays poor adhesion performance and angiogenic activity. In this work, we designed a collagen-binding domain (CBD) containing the core functional amino acid sequences of laminin α4 to supplement the functional surface of a collagen-based DBM scaffold. This bioscaffold promoted SCR-mediated MSCs and EPCs early cell adhesion, thus accelerated the following cell spreading, proliferation, and differentiation. Our results indicate this bioscaffold greatly induced osteogenesis and angiogenesis in vivo. In general, this bioscaffold has a good prospect for SCR application and may provide highly bioactive bone implant in clinical environment.

Phosphorylation inhibition of protein-tyrosine phosphatase 1B tyrosine-152 induces bone regeneration coupled with angiogenesis for bone tissue engineering

A close relationship has been reported to exist between cadherin-mediated cell–cell adhesion and integrin-mediated cell mobility, and protein tyrosine phosphatase 1B (PTP1B) may be involved in maintaining this homeostasis. The stable residence of mesenchymal stem cells (MSCs) and endothelial cells (ECs) in their niches is closely related to the regulation of PTP1B. However, the exact role of the departure of MSCs and ECs from their niches during bone regeneration is largely unknown. Here, we show that the phosphorylation state of PTP1B tyrosine-152 (Y152) plays a central role in initiating the departure of these cells from their niches and their subsequent recruitment to bone defects. Based on our previous design of a PTP1B Y152 region-mimicking peptide (152RM) that significantly inhibits the phosphorylation of PTP1B Y152, further investigations revealed that 152RM enhanced cell migration partly via integrin αvβ3 and promoted MSCs osteogenic differentiation partly by inhibiting ATF3. Moreover, 152RM induced type H vessels formation by activating Notch signaling. Demineralized bone matrix (DBM) scaffolds were fabricated with mesoporous silica nanoparticles (MSNs), and 152RM was then loaded onto them by electrostatic adsorption. The DBM-MSN/152RM scaffolds were demonstrated to induce bone formation and type H vessels expansion in vivo. In conclusion, our data reveal that 152RM contributes to bone formation by coupling osteogenesis with angiogenesis, which may offer a potential therapeutic strategy for bone defects.

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PTP1B plays a dual regulatory role in cadherin- and integrin-related pathways.

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Inhibition of PTP1B Y152 phosphorylation enhances the departure of MSCs from the stem cell niche.

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DBM-MSN/152RM scaffolds coordinate the recruitment of MSCs and ECs.

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DBM-MSN/152RM scaffolds promote bone regeneration and angiogenesis in bone defects.

[Effect of demineralized bone matrix modified by laminin α4 chain functional peptide on H-type angiogenesis and osteogenesis to promote bone defect repair]

Objective

Based on the cell-extracellular matrix adhesion theory in selective cell retention (SCR) technology, demineralized bone matrix (DBM) modified by simplified polypeptide surface was designed to promote both bone regeneration and angiogenesis.

Methods

Functional peptide of α4 chains of laminin protein (LNα4), cyclic RGDfK (cRGD), and collagen-binding domain (CBD) peptides were selected. CBD-LNα4-cRGD peptide was synthesized in solid phase and modified on DBM to construct DBM/CBD-LNα4-cRGD scaffold (DBM/LN). Firstly, scanning electron microscope and laser scanning confocal microscope were used to examine the characteristics and stability of the modified scaffold. Then, the adhesion, proliferation, and tube formation properties of CBD-LNα4-cRGD peptide on endothelial progenitor cells (EPCs) were detected, respectively. Western blot method was used to verify the molecular mechanism affecting EPCs. Finally, 24 10-week-old male C57 mice were used to establish a 2-mm-length defect of femoral bone model. DBM/LN and DBM scaffolds after SCR treatment were used to repair bone defects in DBM/LN group ( n=12) and DBM group ( n=12), respectively. At 8 weeks after operation, the angiogenesis and bone regeneration ability of DBM/LN scaffolds were evaluated by X-ray film, Micro-CT, angiography, histology, and immunofluorescence staining [CD31, endomucin (Emcn), Ki67].

Results

Material related tests showed that the surface of DBM/LN scaffold was rougher than DBM scaffold, but the pore diameter did not change significantly ( t=0.218, P=0.835). After SCR treatment, DBM/LN scaffold was still stable and effective. Compared with DBM scaffold, DBM/LN scaffold could adhere to more EPCs after the surface modification of CBD-LNα4-cRGD ( P<0.05), and the proliferation rate and tube formation ability increased. Western blot analysis showed that the relative expressions of VEGF, phosphorylated FAK (p-FAK), and phosphorylated ERK1/2 (p-ERK1/2) proteins were higher in DBM/LN than in DBM ( P<0.05). In the femoral bone defect model of mice, it was found that mice implanted with DBM/LN scaffold had stronger angiogenesis and bone regeneration capacity ( P<0.05), and the number of CD31 ^hiEmcn ^hi cells increased significantly ( P<0.05).

Conclusion

DBM/LN scaffold can promote the adhesion of EPCs. Importantly, it can significantly promote the generation of H-type vessels and realize the effective coupling between angiogenesis and bone regeneration in bone defect repair.

Biomimetic titanium implant coated with extracellular matrix enhances and accelerates osteogenesis

Aim: To evaluate the biological function of titanium implants coated with cell-derived mineralized extracellular matrix, which mimics a bony microenvironment. Materials & methods: A biomimetic titanium implant was fabricated primarily by modifying the titanium surface with TiO₂ nanotubes or sand-blasted, acid-etched topography, then was coated with mineralized extracellular matrix constructed by culturing bone marrow mesenchymal stromal cells. The osteogenic ability of biomimetic titanium surface in vitro and in vivo were evaluated. Results: In vitro and in vivo studies revealed that the biomimetic titanium implant enhanced and accelerated osteogenesis of bone marrow stromal cells by increasing cell proliferation and calcium deposition. Conclusion: By combining surface topography modification with biological coating, the results provided a valuable method to produce biomimetic titanium implants with excellent osteogenic ability.

Differentiation of neural-type cells on multi-scale ordered collagen-silica bionanocomposites

Cells respond to biophysical and biochemical signals. We developed a composite filament from collagen and silica particles modified to interact with collagen and/or present a laminin epitope (IKVAV) crucial for cell-matrix adhesion and signal transduction. This combines scaffolding and signaling and shows that local tuning of collagen organization enhances cell differentiation.

CD41-deficient exosomes from non-traumatic femoral head necrosis tissues impair osteogenic differentiation and migration of mesenchymal stem cells

Non-traumatic osteonecrosis of the femoral head (ONFH) is clinically a devastating and progressive disease without an effective treatment. Mesenchymal stem cells (MSCs) transplantation has been used to treat ONFH in early stage, but the failure rate of this therapy is high due to the reduced osteogenic differentiation and migration of the transplanted MSCs related with pathological bone tissues. However, the mechanism responsible for this decrease is still unclear. Therefore, we assume that the implanted MSCs might be influenced by signals delivered from pathological bone tissue, where the exosomes might play a critical role in this delivery. This study showed that exosomes from ONFH bone tissues (ONFH-exos) were able to induce GC-induced ONFH-like damage, in vivo and impair osteogenic differentiation and migration of MSCs, in vitro. Then, we analyzed the differentially expressed proteins (DEPs) in ONFH-exos using proteomic technology and identified 842 differentially expressed proteins (DEPs). On the basis of gene ontology (GO) enrichment analysis of DEPs, fold-changes and previous report, cell adhesion-related CD41 (integrin α2b) was selected for further investigation. Our study showed that the CD41 (integrin α2b) was distinctly decreased in ONFH-exos, compared to NOR-exos, and downregulation of CD41 could impair osteogenic differentiation and migration of the MSCs, where CD41-integrin β3-FAK-Akt-Runx2 pathway was involved. Finally, our study further suggested that CD41-affluent NOR-exos could restore the glucocorticoid-induced decline of osteogenic differentiation and migration in MSCs, and prevent GC-induced ONFH-like damage in rat models. Taken together, our study results revealed that in the progress of ONFH, exosomes from the pathological bone brought about the failure of MSCs repairing the necrotic bone for lack of some critical proteins, like integrin CD41, and prompted the progression of experimentally induced ONFH-like status in the rat. CD41 could be considered as the target of early diagnosis and therapy in ONFH.

Evidence that TNF-β suppresses osteoblast differentiation of mesenchymal stem cells and resveratrol reverses it through modulation of NF-κB, Sirt1 and Runx2

It has been established that inflammation plays an important role in bone formation and bone loss. Although a lot is known about the role of TNF-α in bone health, very little is understood about TNF-β, also called lymphotoxin. In this report, we examine the effect of TNF-β on osteogenic differentiation of mesenchymal stem cells (MSCs) and its modulation by resveratrol. Monolayer and high-density cultures of MSCs were treated with osteogenic induction medium with/without TNF-β, Sirt1 inhibitor nicotinamide (NAM), antisense oligonucleotides against Sirt1 (ASO) and/or Sirt1 stimulator resveratrol. We found that TNF-β inhibits, in a similar way to NAM or Sirt1-ASO, the early stage of osteogenic differentiation of MSCs and this was accompanied with downregulation of bone-specific matrix, β1-integrin, Runx2 and with upregulation of NF-κB phosphorylation and NF-κB-regulated gene products involved in the inflammatory, degradative processes and apoptosis. However, resveratrol reversed TNF-β- and NAM-suppressed MSCs osteogenesis by activation of Sirt1 and Runx2 that led to osteoblast differentiation. Furthermore, downregulation of Sirt1 by mRNA inhibited the effect of resveratrol, highlighting the important impact of this enzyme in the TNF-β signaling pathway. Finally, resveratrol was able to manifest its effect both by suppression of TNF-β-induced NF-κB and through direct activation of the Sirt1 and Runx2 pathway. Thus, through these studies, we present a mechanism by which a T cell-derived cytokine, TNF-β can affect bone formation through modulation of MSCs differentiation that involves NF-κB, Sirt1, Runx2 and resveratrol reversed TNF-β-promoted impairments in MSCs osteogenesis.

Inhibition of protein-tyrosine phosphatase 1B phosphorylation enhances early adhesion of mesenchymal stem cells to facilitate fabrication of tissue-engineered bone

Enhancement of cell-matrix adhesion is preferable and crucial in various fields of tissue engineering. Integrins are important receptors that facilitate cell-matrix adhesion, mediated by intracellular molecules and crosstalk with the cadherin adhesion pathway, which mainly facilitates cell-cell adhesion. Protein-tyrosine phosphatase 1B (PTP1B) has emerged as a pivot in the crosstalk between the cadherin adhesion pathway and the integrin adhesion pathway. The phosphorylation state of PTP1B tyrosine-152 (Y152) plays a central role in balancing the two different cell adhesion forms. In this study, a PTP1B Y152 region mimicking (152RM) peptide was designed to decrease the phosphorylation of PTP1B Y152 via competitive inhibition. As a result, the dissociation of cadherin complexes and the release of PTP1B from cadherin had sharply increased, and Src, an important intracellular component of integrin, was activated, indicating that the cadherin adhesion pathway was inhibited, whereas the integrin adhesion pathway was enhanced. Moreover, upon treatment with the 152RM peptide, we observed that the early adhesion of human bone marrow-derived mesenchymal stem cells (MSCs) was accelerated and the anchoring of MSCs on the surface of integrin ligands was enhanced by an enhanced matrix adhesion ability of MSCs themselves. Importantly, the 152RM peptide significantly promoted the adhesion efficiency of MSCs in the selective cell retention technology, which fabricates instant bone implants in clinical settings, to stimulate osteogenesis in vivo.