Guiding Fibroblast Activation Using an RGD-Mutated Heparin Binding II Fragment of Fibronectin for Gingival Titanium Integration

De Novo Design of Integrin α5β1 Modulating Proteins for Regenerative Medicine

Integrin α5β1 is crucial for cell attachment and migration in development and tissue regeneration, and α5β1 binding proteins could have considerable utility in regenerative medicine and next-generation therapeutics. We use computational protein design to create de novo α5β1-specific modulating miniprotein binders, called NeoNectins, that bind to and stabilize the open state of α5β1. When immobilized onto titanium surfaces and throughout 3D hydrogels, the NeoNectins outperform native fibronectin and RGD peptide in enhancing cell attachment and spreading, and NeoNectin-grafted titanium implants outperformed fibronectin and RGD-grafted implants in animal models in promoting tissue integration and bone growth. NeoNectins should be broadly applicable for tissue engineering and biomedicine.

Effect of Functionalization of Texturized Polypropylene Surface by Silanization and HBII-RGD Attachment on Response of Primary Abdominal and Vaginal Fibroblasts

Soft tissue defects, such as incisional hernia or pelvic organ prolapse, are prevalent pathologies characterized by a tissue microenvironment rich in fragile and dysfunctional fibroblasts. Precision medicine could improve their surgical repair, currently based on polymeric materials. Nonetheless, biomaterial-triggered interventions need first a better understanding of the cell-material interfaces that truly consider the patients' biology. Few tools are available to study the interactions between polymers and dysfunctional soft tissue cells in vitro. Here, we propose polypropylene (PP) as a matrix to create microscale surfaces w/wo functionalization with an HBII-RGD molecule, a fibronectin fragment modified to include an RGD sequence for promoting cell attachment and differentiation. Metal mold surfaces were roughened by shot blasting with aluminum oxide, and polypropylene plates were obtained by injection molding. HBII-RGD was covalently attached by silanization. As a proof of concept, primary abdominal and vaginal wall fasciae fibroblasts from control patients were grown on the new surfaces. Tissue-specific significant differences in cell morphology, early adhesion and cytoskeletal structure were observed. Roughness and biofunctionalization parameters exerted unique and combinatorial effects that need further investigation. We conclude that the proposed model is effective and provides a new framework to inform the design of smart materials for the treatment of clinically compromised tissues.

Enhancing osseointegration of titanium implants through MC3T3-E1 protein-gelatin polyelectrolyte multilayers

Titanium and its alloys have found extensive use in the biomedical field, however, implant loosening due to weak osseointegration remains a concern. Improved surface morphology and chemical composition can enhance the osseointegration of the implant. Bioactive molecules have been utilized to modify the surface of the titanium-based material to achieve rapid and efficient osseointegration between the implant and bone tissues. In this study, the bioactive substance MC3T3-E1 protein-gelatin polyelectrolyte multilayers were constructed on the surface of the titanium implants by means of layer-by-layer self-assembly to enhance the strength of the bond between the bone tissue and the implant. The findings of the study indicate that the layer-by-layer self-assembly technique can enhance surface roughness and hydrophilicity to a considerable extent. Compared to pure titanium, the hydrophilicity of TiOH LBL was significantly increased with a water contact angle of 75.0 ± $$ \pm $$ 2.4°. The modified titanium implant exhibits superior biocompatibility and wound healing ability upon co-culture with cells. MC3T3-E1 cells were co-cultured with TiOH LBL for 1, 3, and 5 days and their viability was higher than 85%. In addition, the wound healing results demonstrate that TiOH LBL exhibited the highest migratory ability (243 ± 10 μm). Furthermore, after 7 days of osteogenic induction, the modified titanium implant significantly promotes osteoblast differentiation.

Zn2+ Differentially Influences the Neutralisation of Heparins by HRG, Fibrinogen, and Fibronectin

For coagulation to be initiated, anticoagulant glycosaminoglycans (GAGs) such as heparins need to be neutralised to allow fibrin clot formation. Platelet activation triggers the release of several proteins that bind GAGs, including histidine-rich glycoprotein (HRG), fibrinogen, and fibronectin. Zn2+ ions are also released and have been shown to enhance the binding of HRG to heparins of a high molecular weight (HMWH) but not to those of low molecular weight (LMWH). The effect of Zn2+ on fibrinogen and fibronectin binding to GAGs is unknown. Here, chromogenic assays were used to measure the anti-factor Xa and anti-thrombin activities of heparins of different molecular weights and to assess the effects of HRG, fibrinogen, fibronectin, and Zn2+. Surface plasmon resonance was also used to examine the influence of Zn2+ on the binding of fibrinogen to heparins of different molecular weights. Zn2+ had no effect on the neutralisation of anti-factor Xa (FXa) or anti-thrombin activities of heparin by fibronectin, whereas it enhanced the neutralisation of unfractionated heparin (UFH) and HMWH by both fibrinogen and HRG. Zn2+ also increased neutralisation of the anti-FXa activity of LMWH by fibrinogen but not HRG. SPR showed that Zn2+ increased fibrinogen binding to both UFH and LMWH in a concentration-dependent manner. The presented results reveal that an increase in Zn2+ concentration has differential effects upon anticoagulant GAG neutralisation by HRG and fibrinogen, with implications for modulating anti-coagulant activity in plasma.