Anti-fibronectin aptamers improve the colonization of chitosan films modified with D-(+) Raffinose by murine osteoblastic cells

Anti-Fibronectin Aptamer Modifies Blood Clot Pattern and Stimulates Osteogenesis: An Ex Vivo Study

BACKGROUND

Scaffold (SCA) functionalization with aptamers (APT) provides adsorption of specific bioactive molecules on biomaterial surfaces. The aim of this study was to observe if SCA enriched with anti-fibronectin APT can favor coagulum (PhC) and osteoblasts (OSB) differentiation.

METHODS

20 μg of APT was functionalized on SCA by simple adsorption. For PhC formation, SCAs were inserted into rat calvaria defects for 17 h. Following proper transportation (buffer solution PB), OSBs (UMR-106 lineage) were seeded over PhC + SCAs with and without APT. Cells and PhC morphology, PhC cell population, protein labeling and gene expression were observed in different time points.

RESULTS

The APT induced higher alkaline phosphatase and bone sialoprotein immunolabeling in OSB. Mesenchymal stem cells, leukocytes and lymphocytes cells were detected more in the APT group than when scaffolds were not functionalized. Additionally, an enriched and dense fibrin network and different cell types were observed, with more OSB and white blood cells in PhC formed on SCA with APT. The gene expression showed higher transforming growth factor beta 1 (TGF-b1) detection in SCA with APT.

CONCLUSIONS

The SCA functionalization with fibronectin aptamers may alter key morphological and functional features of blood clot formation, and provides a selective expression of proteins related to osteo differentiation. Additionally, aptamers increase TGF-b1 gene expression, which is highly associated with improvements in regenerative therapies.

Aptamer-enriched scaffolds for tissue regeneration: a systematic review of the literature

Introduction: Aptamers are a brand-new class of receptors that can be exploited to improve the bioactivity of tissue engineering grafts. The aim of this work was to revise the current literature on in vitro and in vivo studies in order to i) identify current strategies adopted to improve scaffold bioactivity by aptamers; ii) assess effects of aptamer functionalization on cell behavior and iii) on tissue regeneration. Methods: Using a systematic search approach original research articles published up to 30 April 2022, were considered and screened. Results: In total, 131 records were identified and 18 were included in the final analysis. Included studies showed that aptamers can improve the bioactivity of biomaterials by specific adsorption of adhesive molecules or growth factors from the surrounding environment, or by capturing specific cell types. All the studies showed that aptamers ameliorate scaffold colonization by cells without modifying the physicochemical characteristics of the bare scaffold. Additionally, aptamers seem to promote the early stages of tissue healing and to promote anatomical and functional regeneration. Discussion: Although a metanalysis could not be performed due to the limited number of studies, we believe these findings provide solid evidence supporting the use of aptamers as a suitable modification to improve the bioactivity of tissue engineering constructs.

Fibronectin-Enriched Biomaterials, Biofunctionalization, and Proactivity: A Review

Modern innovation in reconstructive medicine implies the proposition of material-based strategies suitable for tissue repair and regeneration. The development of such systems necessitates the design of advanced materials and the control of their interactions with their surrounding cellular and molecular microenvironments. Biomaterials must actively engage cellular matter to direct and modulate biological responses at implant sites and beyond. Indeed, it is essential that a true dialogue exists between the implanted device and the cells. Biomaterial engineering implies the knowledge and control of cell fate considering the globality of the adhesion process, from initial cell attachment to differentiation. The extracellular matrix (ECM) represents a complex microenvironment able to meet these essential needs to establish a relationship between the material and the contacting cells. The ECM exhibits specific physical, chemical, and biochemical characteristics. Considering the complexity, heterogeneity, and versatility of ECM actors, fibronectin (Fn) has emerged among the ECM protagonists as the most pertinent representative key actor. The following review focuses on and synthesizes the research supporting the potential to use Fn in biomaterial functionalization to mimic the ECM and enhance cell–material interactions.

Polymeric Biomaterials for the Treatment of Cardiac Post-Infarction Injuries

Cardiac regeneration aims to reconstruct the heart contractile mass, preventing the organ from a progressive functional deterioration, by delivering pro-regenerative cells, drugs, or growth factors to the site of injury. In recent years, scientific research focused the attention on tissue engineering for the regeneration of cardiac infarct tissue, and biomaterials able to anatomically and physiologically adapt to the heart muscle have been proposed as valuable tools for this purpose, providing the cells with the stimuli necessary to initiate a complete regenerative process. An ideal biomaterial for cardiac tissue regeneration should have a positive influence on the biomechanical, biochemical, and biological properties of tissues and cells; perfectly reflect the morphology and functionality of the native myocardium; and be mechanically stable, with a suitable thickness. Among others, engineered hydrogels, three-dimensional polymeric systems made from synthetic and natural biomaterials, have attracted much interest for cardiac post-infarction therapy. In addition, biocompatible nanosystems, and polymeric nanoparticles in particular, have been explored in preclinical studies as drug delivery and tissue engineering platforms for the treatment of cardiovascular diseases. This review focused on the most employed natural and synthetic biomaterials in cardiac regeneration, paying particular attention to the contribution of Italian research groups in this field, the fabrication techniques, and the current status of the clinical trials.

Aptamers recognizing fibronectin confer improved bioactivity to biomaterials and promote new bone formation in a periodontal defect in rats

The use of alloplastic materials in periodontal regenerative therapies is limited by their incapacity to establish a dynamic dialog with the surrounding milieu. The aim of the present study was to control biomaterial surface bioactivity by introducing aptamers to induce the selective adsorption of fibronectin from blood, thus promoting platelets activation in vitro and bone regeneration in vivo. A hyaluronic acid/polyethyleneglycole-based hydrogel was enriched with aptamers selected for recognizing and binding fibronectin. In vitro, the capacity of constructs to support osteoblast adhesion, as well as platelets aggregation and activation was assessed by chemiluminescence within 24 h. Matrices were then evaluated in a rat periodontal defect to assess their regenerative potential by microcomputed tomography (µCT) and their osteogenic capacity by Luminex assay 5, 15 and 30 d postoperatively. Aptamers were found to confer matrices the capacity of sustaining firm cell adhesion (p = 0.0377) and to promote platelets activation (p = 0.0442). In vivo, aptamers promoted new bone formation 30 d post-operatively (p < 0.001) by enhancing osteoblastic lineage commitment maturation. Aptamers are a viable surface modification, which confers alloplastic materials the potential capacity to orchestrate blood clot formation, thus controlling bone healing.

The Body's Cellular and Molecular Response to Protein-Coated Medical Device Implants: A Review Focused on Fibronectin and BMP Proteins

Recent years have seen a marked rise in implantation into the body of a great variety of devices: hip, knee, and shoulder replacements, pacemakers, meshes, glucose sensors, and many others. Cochlear and retinal implants are being developed to restore hearing and sight. After surgery to implant a device, adjacent cells interact with the implant and release molecular signals that result in attraction, infiltration of the tissue, and attachment to the implant of various cell types including monocytes, macrophages, and platelets. These cells release additional signaling molecules (chemokines and cytokines) that recruit tissue repair cells to the device site. Some implants fail and require additional revision surgery that is traumatic for the patient and expensive for the payer. This review examines the literature for evidence to support the possibility that fibronectins and BMPs could be coated on the implants as part of the manufacturing process so that the proteins could be released into the tissue surrounding the implant and improve the rate of successful implantation.

Tetracalcium phosphate and biphasic tetracalcium phosphate/tricalcium phosphate powders' effects evaluation on human osteoblasts

BACKGROUND

Calcium ions levels in bone niches have been demonstrated to severely influence new bone formation. Osteoinductive scaffolds containing calcium have been largely studied to control the release of calcium in bone regeneration and tissue engineering purpose. The aim of the present study was, firstly, to synthesize two different resorbable calcium phosphate-based powders, thought to be reservoirs of calcium ions, and secondary, to investigate their effects on human osteoblasts, in order to develop a suitable titanium coating material.

METHODS

Tetracalcium phosphate (A450) and biphasic tetracalcium phosphatae/tricalcium phosphate (A850) powders were prepared with an innovative method. The presence of calcium phosphate structures was chemically confirmed with XRD. Furthermore, powders macroscopic aspect was observed with a stereomicroscope. For in-vitro experiments, human osteoblastic cells were cultured in the presence of A450 and A850, and assayed for viability and metabolic activity through Crystal Violet and MTT, respectively.

RESULTS

Our synthesis led to the formation of calcium phosphates in both samples, even though A850 presented a higher level of crystallinity and a more powdery aspects than A450. Both the samples enhanced the viability of cultured cells, inhibiting cell metabolic activity in the case of A850, which furthermore showed to be internalized by cells.

CONCLUSIONS

We developed two different kind of calcium phosphate-based powders and we tested their effect on human osteoblasts, underlying the possibility of use calcium phosphate-based coatings to enhance cell response on implantable materials.

A glance on the role of fibronectin in controlling cell response at biomaterial interface

The bioactivity of biomaterials is closely related to cell response in contact with them. However, shortly after their insertion, materials are soon covered with proteins that constitute the biological fluids, and which render the direct surface recognition by cells almost impossible. The control of protein adsorption at the interface is therefore desirable. Extracellular matrix proteins are of particular interest in this sense, due to their well-known ability to modulate cell behavior. Particularly, fibronectin plays a leading role, being present in both healthy and injured tissues undergoing healing and regeneration. The aim of the present work is to give an overview on fibronectin and on its involvement in the control of cell behavior providing evidence of its pivotal role in the control of cell adhesion, spreading, migration, proliferation and differentiation. A deep insight into methods to enrich biomaterials surface with fibronectin will be then discussed, as well as new cues on the possibility to design tailored platforms able to specifically retain fibronectin from the surrounding extracellular milieu.

Thermal treatment to increase titanium wettability induces selective proteins adsorption from blood serum thus affecting osteoblasts adhesion

OBJECTIVES

To investigate how a thermal treatment to increase titanium wettability influences proteins adsorption from blood serum and osteoblasts responses.

METHODS

Titanium discs with machined or micro-rough profiles were thermally treated to obtain hydrophilic surfaces. The adsorption kinetics of two representative serum proteins were determined by Bradford assay, while the stable protein adsorption pattern from blood serum was investigated by SDS-PAGE and Western Blot analysis. Subsequently, MC3T3-E1 cells were cultured on titanium for 24h and assayed for adhesion and morphology.

RESULTS

Thermally-induced hydrophilicity dramatically improved the capacity of titanium to selectively adsorb fibronectin and fibrinogen from blood serum, without evident influence on other representative serum proteins. The selective adsorption of fibronectin was linked to the improved capacity of MC3T3-E1 cells to adhere and spread on hydrophilic surfaces.

SIGNIFICANCE

We identified a potential method to improve selective protein adsorption on titanium by enhancing implant surface wettability through a thermal treatment. Selective fibronectin adsorption was further indicated as the responsible for improved osteoblasts adhesion. Targeting specific cell response by selective protein adsorption appears to be crucial to conceive even more performant therapies.

Is selective protein adsorption on biomaterials a viable option to promote periodontal regeneration?

Periodontitis is an inflammatory condition that can induce significant destruction of the periodontium, the set of specialized tissues that provide nourishment and support to the teeth. According to the guided tissue regeneration principles, the periodontium can be regenerated if the spatiotemporal control of wound healing is obtained, namely the tune control of cell response. After material implantation, protein adsorption at the interface is the first occurring biological event, which influences subsequent cell response. With the regard of this, we hypothesize that the control of selective adsorption of biological cues from the surrounding milieu may be a key-point to control selective cell colonization of scaffolds for periodontal tissue regeneration.

Osteoblast adhesion and response mediated by terminal -SH group charge surface of SiOxCy nanowires

Robust cell adhesion is known to be necessary to promote cell colonization of biomaterials and differentiation of progenitors. In this paper, we propose the functionalization of Silicon Oxycarbide (SiO_xC_y) nanowires (NWs) with 3-mercaptopropyltrimethoxysilane (MPTMS), a molecule containing a terminal -SH group. The aim of this functionalization was to develop a surface capable to adsorb proteins and promote cell adhesion, proliferation and a better deposition of extracellular matrix. This functionalization can be used to anchor other structures such as nanoparticles, proteins or aptamers. It was observed that surface functionalization markedly affected the pattern of protein adsorption, as well as the in vitro proliferation of murine osteoblastic cells MC3T3-E1, which was increased on functionalized nanowires (MPTMS-NWs) compared to bare NWs (control) (p < 0.0001) after 48 h. The cells showed a better adhesion on MPTMS-NWs than on bare NWs, as confirmed by immunofluorescence studies on the cytoskeleton, which showed a more homogeneous vinculin distribution. Gene expression analysis showed higher expression levels for alkaline phosphatase and collagen I, putative markers of the osteoblast initial differentiation stage. These results suggest that functionalization of SiO_xC_y nanowires with MPTMS enhances cell growth and the expression of an osteoblastic phenotype, providing a promising strategy to improve the biocompatibility of SiO_xC_y nanowires for biomedical applications.

Functional Fibronectin Adsorption on Aptamer-Doped Chitosan Modulates Cell Morphology by Integrin-Mediated Pathway

A decisive step in cell-biomaterial interaction is represented by the adsorption of proteins at the interface, whose fine control may be useful to trigger proper cell response. To this purpose, we can selectively control protein adsorption on biomaterials by means of aptamers. Aptamers selected to recognize fibronectin dramatically enhance chitosan ability to promote cell proliferation and adhesion, but the underlying biological mechanism remains unknown. We supposed that aptamers contributed to ameliorate the adsorption of fibronectin in an advantageous geometrical conformation for cells, thus regulating their morphology by the proper activation of the integrin-mediated pathway. We investigated this possibility by culturing epithelial cells on chitosan enriched with increasing doses of aptamers in the presence or in the absence of cytoskeleton pharmacological inhibitors. Our results showed that aptamers control cell morphology in a dose dependent manner (p < 0.0001). Simultaneously, when the inhibition of actin polymerization was induced, the control of cell morphology was attenuated (p < 0.0001), while no differences were detected when cells contractility was challenged (p > 0.05). Altogether, our data provide evidence that aptamers contribute to control fibronectin adsorption on biomaterials by preserving its conformation and thus function. Furthermore, our work provides a new insight into a new way to accurately tailor material surface bioactivity.

Tailoring the Interface of Biomaterials to Design Effective Scaffolds

Tissue engineering (TE) is a multidisciplinary science, which including principles from material science, biology and medicine aims to develop biological substitutes to restore damaged tissues and organs. A major challenge in TE is the choice of suitable biomaterial to fabricate a scaffold that mimics native extracellular matrix guiding resident stem cells to regenerate the functional tissue. Ideally, the biomaterial should be tailored in order that the final scaffold would be (i) biodegradable to be gradually replaced by regenerating new tissue, (ii) mechanically similar to the tissue to regenerate, (iii) porous to allow cell growth as nutrient, oxygen and waste transport and (iv) bioactive to promote cell adhesion and differentiation. With this perspective, this review discusses the options and challenges facing biomaterial selection when a scaffold has to be designed. We highlight the possibilities in the final mold the materials should assume and the most effective techniques for its fabrication depending on the target tissue, including the alternatives to ameliorate its bioactivity. Furthermore, particular attention has been given to the influence that all these aspects have on resident cells considering the frontiers of materiobiology. In addition, a focus on chitosan as a versatile biomaterial for TE scaffold fabrication has been done, highlighting its latest advances in the literature on bone, skin, cartilage and cornea TE.

Physicochemical and pharmacokinetic properties of polymeric films loaded with cisplatin for the treatment of malignant pleural mesothelioma

Background

Malignant mesothelioma is an invasive neoplasm arising from mesothelial surfaces of the pleural and peritoneal cavities. Mesothelioma treatment is unsatisfactory and recurrence is common. Here an innovative locoregional treatment for malignant pleural mesothelioma is presented.

Methods

Chitosan- and hyaluronate-based films were loaded with 0.5% and 4% w/w cisplatin and were studied for their physicochemical, mechanical and drug release characteristics. The performance of the drug delivery systems was assessed in vitro on A549 cells and on an orthotopic model of MPM recurrence in rats.

Results

Polysaccharide films produced were thin, flexible and resistant. Cisplatin was completely released from hyaluronic acid films within 96 hours, while drug release was found to be much more prolonged with chitosan films. The drug released from hyaluronate films was effective against A549 cell line, while for chitosan films the release was too slow to produce cytotoxicity. Similarly, cisplatin-loaded chitosan films in vivo released minimal quantities of cisplatin and induced inflammation and foreign body reaction. Cisplatin-loaded hyaluronate acid films on the contrary were able to prevent tumor recurrence. The cisplatin-loaded hyaluronate films provided higher C_max and AUC compared to a solution of cisplatin administered intrapleurally, but did not show any sign of treatment related toxicity.

Conclusions

Hyaluronate-based films appear as an optimal platform for the development of drug delivery systems suitable for the loco-regional post-surgical treatment of lung malignancies.