Microporous Polyurethane Thin Layer as a Promising Scaffold for Tissue Engineering

AlveoMPU: Bridging the Gap in Lung Model Interactions Using a Novel Alveolar Bilayer Film

The alveoli, critical sites for gas exchange in the lungs, comprise alveolar epithelial cells and pulmonary capillary endothelial cells. Traditional experimental models rely on porous polyethylene terephthalate or polycarbonate membranes, which restrict direct cell-to-cell contact. To address this limitation, we developed AlveoMPU, a new foam-based mortar-like polyurethane-formed alveolar model that facilitates direct cell-cell interactions. AlveoMPU features a unique anisotropic mortar-shaped configuration with larger pores at the top and smaller pores at the bottom, allowing the alveolar epithelial cells to gradually extend toward the bottom. The underside of the film is remarkably thin, enabling seeded pulmonary microvascular endothelial cells to interact with alveolar epithelial cells. Using AlveoMPU, it is possible to construct a bilayer structure mimicking the alveoli, potentially serving as a model that accurately simulates the actual alveoli. This innovative model can be utilized as a drug-screening tool for measuring transepithelial electrical resistance, assessing substance permeability, observing cytokine secretion during inflammation, and evaluating drug efficacy and pharmacokinetics.

Production of Plant-Based, Film-Type Scaffolds Using Alginate and Corn Starch for the Culture of Bovine Myoblasts

Natural scaffolds have been the cornerstone of tissue engineering for decades, providing ideal environments for cell growth within extracellular matrices. Previous studies have favored animal-derived materials, including collagen, gelatin, and laminin, owing to their superior effects in promoting cell attachment, proliferation, and differentiation compared to non-animal scaffolds, and used immortalized cell lines. However, for cultured meat production, non-animal-derived scaffolds with edible cells are preferred. Our study represents the first research to describe plant-derived, film-type scaffolds to overcome limitations associated with previously reported thick, gel-type scaffolds completely devoid of animal-derived materials. This approach has been employed to address the difficulties of fostering bovine muscle cell survival, migration, and differentiation in three-dimensional co-cultures. Primary bovine myoblasts from Bos Taurus Coreanae were harvested and seeded on alginate (Algi) or corn-derived alginate (AlgiC) scaffolds. Scaffold functionalities, including biocompatibility and the promotion of cell proliferation and differentiation, were evaluated using cell viability assays, immunofluorescence staining, and reverse transcription-quantitative polymerase chain reaction. Our results reveal a statistically significant 71.7% decrease in production time using film-type scaffolds relative to that for gel-type scaffolds, which can be maintained for up to 7 days. Film-type scaffolds enhanced initial cell attachment owing to their flatness and thinness relative to gel-type scaffolds. Algi and AlgiC film-type scaffolds both demonstrated low cytotoxicity over seven days of cell culture. Our findings indicated that PAX7 expression increased 16.5-fold in alginate scaffolds and 22.8-fold in AlgiC from day 1 to day 3. Moreover, at the differentiation stage on day 7, MHC expression was elevated 41.8-fold (Algi) and 32.7-fold (AlgiC), providing initial confirmation of the differentiation potential of bovine muscle cells. These findings suggest that both Algi and AlgiC film scaffolds are advantageous for cultured meat production.

Investigation on Filaments for 3D Printing of Nasal Septum Cartilage Implant

Septoplasty is a widely used method in treating deviated septum. Although it is successfully implemented, there are problems with excessive bleeding, septal perforation, or infections. The use of anatomically shaped implants could help overcome these problems. This paper focuses on assessing the possibility of the usage of a nasal septum cartilage implant 3D printed from various market-available filaments. Five different types of laments were used, two of which claim to be suitable for medical use. A combination of modeling, mechanical (bending, compression), structural (FTIR), thermal (DSC, MFR), surface (contact angle), microscopic (optical), degradation (2 M HCl, 5 M NaOH, and 0.01 M PBS), printability, and cell viability (MTT) analyses allowed us to assess the suitability of materials for manufacturing implants. Bioflex had the most applicable properties among the tested materials, but despite the overall good performance, cell viability studies showed toxicity of the material in MTT test. The results of the study show that selected filaments were not suitable for nasal cartilage implants. The poor cell viability of Bioflex could be improved by surface modification. Further research on biocompatible elastic materials for 3D printing is needed either by the synthesis of new materials or by modifying existing ones.

Recent Advancements in Polyurethane-based Tissue Engineering

In tissue engineering, polyurethane-based implants have gained significant traction because of their high compatibility and inertness. The implants therefore show fewer side effects and lasts longer. Also, the mechanical properties can be tuned and morphed into a particular shape, owing to which polyurethanes show immense versatility. In the last 3 years, scientists have devised methods to enhance the strength of and induce dynamic properties in polyurethanes, and these developments offer an immense opportunity to use them in tissue engineering. The focus of this review is on applications of polyurethane implants for biomedical application with detailed analysis of hard tissue implants like bone tissues and soft tissues like cartilage, muscles, skeletal tissues, and blood vessels. The synthetic routes for the preparation of scaffolds have been discussed to gain a better understanding of the issues that arise regarding toxicity. The focus here is also on concerns regarding the biocompatibility of the implants, given that the precursors and byproducts are poisonous.

Polyurethane based hybrid ciprofloxacin-releasing wound dressings designed for skin engineering purpose

PURPOSE

Even in the 21st century, chronic wounds still pose a major challenge due to potentially inappropriate treatment options, so the latest wound dressings are hybrid systems that enable clinical management, such as a hybrid of hydrogels, antibiotics and polymers. These wound dressings are mainly used for chronic and complex wounds, which can easily be infected by bacteria.

MATERIALS AND METHODS

Six Composite Porous Matrices (CPMs) based on polyurethane (PUR) in alliance with polylactide (PLAs) and poly(vinyl alcohol) (PVA) were prepared and analyzed using optical microscopy. Three different types of hydrogels and their Ciprofloxacin (Cipro) modified variants' ratios were prepared and analyzed using FTIR, SEM and EDX techniques. Six Hybrid Cipro-Releasing Hydrogel Wound Dressings (H-CRWDs) were also prepared and underwent short-term degradation, Cipro release, microbiology and cell viability measurements.

RESULTS

Average porosity of CPMs was in the range of 69-81%. The pore size of the obtained CPMs was optimal for skin regeneration. Short-term degradation studies revealed degradability in physiological conditions regardless of sample type. A meaningful release was also observed even in short time (21.76 ​± ​0.64 ​μg/mL after 15 ​min). Microbiological tests showed visible inhibition zones. Cell viability tests proved that the obtained H-CRWDs were biocompatible (over 85% of cells).

CONCLUSIONS

A promising hybrid wound dressing was labeled. Simple and cost-effective methods were used to obtain microbiologically active and biocompatible dressings. The results were of importance for the design and development of acceptable solutions in the management of chronic wounds of high potential for infection.

Combination of Nitric Oxide Release and Surface Texture for Mitigating the Foreign Body Response

The tissue response to polyurethane (PU)-coated implants employing active and/or passive FBR mitigation techniques was evaluated over a 28 day study in a diabetic swine model. Active FBR mitigation was achieved through the sustained release of nitric oxide (NO) from a mesoporous silica nanoparticle-doped PU coating. Passive FBR mitigation was achieved through the application of a foam- or fiber-based topcoat. These topcoats were designed to possess topographical features known to promote tissue integration with foam-coated implants having pore sizes of approximately 50 μm and fiber-coated implants consisting of fiber diameters of less than 1 μm. Nitric oxide-release profiles were minimally impacted by the presence of either topcoat. Inflammatory cell density and collagen density at the implant-tissue interface were assessed at 7, 14, 21, and 28 days following implantation. Nitric oxide-releasing implants had significantly lower inflammatory cell density and collagen density than non-NO-releasing controls. The presence of a topcoat did not significantly impact inflammatory cell density, though top-coated textured implants resulted in significantly lower collagen density, irrespective of NO release. Overall, coatings that combine NO release with surface texture demonstrated the greatest potential for tissue-based biomedical device applications.

Biobased polyurethanes for biomedical applications

Polyurethanes (PUs) are a major family of polymers displaying a wide spectrum of physico-chemical, mechanical and structural properties for a large range of fields. They have shown suitable for biomedical applications and are used in this domain since decades. The current variety of biomass available has extended the diversity of starting materials for the elaboration of new biobased macromolecular architectures, allowing the development of biobased PUs with advanced properties such as controlled biotic and abiotic degradation. In this frame, new tunable biomedical devices have been successfully designed. PU structures with precise tissue biomimicking can be obtained and are adequate for adhesion, proliferation and differentiation of many cell's types. Moreover, new smart shape-memory PUs with adjustable shape-recovery properties have demonstrated promising results for biomedical applications such as wound healing. The fossil-based starting materials substitution for biomedical implants is slowly improving, nonetheless better renewable contents need to be achieved for most PUs to obtain biobased certifications. After a presentation of some PU generalities and an understanding of a biomaterial structure-biocompatibility relationship, recent developments of biobased PUs for non-implantable devices as well as short- and long-term implants are described in detail in this review and compared to more conventional PU structures.

Simvastatin-loaded graphene oxide embedded in polycaprolactone-polyurethane nanofibers for bone tissue engineering applications

Here, the role of simvastatin-loaded graphene oxide embedded in polyurethane-polycaprolactone nanofibers for bone tissue engineering has been investigated. The scaffolds were physicochemically and mechanically characterized, and obtained polymeric composites were used as MG-63 cell culture scaffolds. The addition of graphene oxide-simvastatin to nanofibers generates a homogeneous and uniform microstructure as well as a reduction in fiber diameter. Results of water-scaffolds interaction indicated higher hydrophilicity and absorption capacity as a function of graphene oxide addition. Scaffolds’ mechanical properties and physical stability improved after the addition of graphene oxide. Inducing bioactivity after the addition of simvastatin-loaded graphene oxide terminated its capability for hard tissue engineering application, evidenced by microscopy images and phase characterization. Nanofibrous scaffolds could act as a sustained drug carrier. Using the optimal concentration of graphene oxide-simvastatin is necessary to avoid toxic effects on tissue. Results show that the scaffolds are biocompatible to the MG-63 cell and support alkaline phosphatase activity, illustrating their potential use in bone tissue engineering. Briefly, graphene-simvastatin-incorporated in polymeric nanofibers was developed to increase bioactive components’ synergistic effect to induce more bioactivity and improve physical and mechanical properties as well as in vitro interactions for better results in bone repair.

Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications

Being biodegradable and biocompatible are crucial characteristics for biomaterial used for medical and biomedical applications. Vegetable oil-based polyols are known to contribute both the biodegradability and biocompatibility of polyurethanes; however, petrochemical-based polyols were often incorporated to improve the thermal and mechanical properties of polyurethane. In this work, palm oil-based polyester polyol (PPP) derived from epoxidized palm olein and glutaric acid was reacted with isophorone diisocyanate to produce an aliphatic polyurethane, without the incorporation of any commercial petrochemical-based polyol. The effects of water content and isocyanate index were investigated. The polyurethanes produced consisted of > 90% porosity with interconnected micropores and macropores (37-1700 µm) and PU 1.0 possessed tensile strength and compression stress of 111 kPa and 64 kPa. The polyurethanes with comparable thermal stability, yet susceptible to enzymatic degradation with 7-59% of mass loss after 4 weeks of treatment. The polyurethanes demonstrated superior water uptake (up to 450%) and did not induce significant changes in pH of the medium. The chemical changes of the polyurethanes after enzymatic degradation were evaluated by FTIR and TGA analyses. The polyurethanes showed cell viability of 53.43% and 80.37% after 1 and 10 day(s) of cytotoxicity test; and cell adhesion and proliferation in cell adhesion test. The polyurethanes produced demonstrated its potential as biomaterial for soft tissue engineering applications.

Recent advances in tissue engineering scaffolds based on polyurethane and modified polyurethane

Organ repair, regeneration, and transplantation are constantly in demand due to various acute, chronic, congenital, and infectious diseases. Apart from traditional remedies, tissue engineering (TE) is among the most effective methods for the repair of damaged tissues via merging the cells, growth factors, and scaffolds. With regards to TE scaffold fabrication technology, polyurethane (PU), a high-performance medical grade synthetic polymer and bioactive material has gained significant attention. PU possesses exclusive biocompatibility, biodegradability, and modifiable chemical, mechanical and thermal properties, owing to its unique structure-properties relationship. During the past few decades, PU TE scaffold bioactive properties have been incorporated or enhanced with biodegradable, electroactive, surface-functionalised, ayurvedic products, ceramics, glass, growth factors, metals, and natural polymers, resulting in the formation of modified polyurethanes (MPUs). This review focuses on the recent advances of PU/MPU scaffolds, especially on the biomedical applications in soft and hard tissue engineering and regenerative medicine. The scientific issues with regards to the PU/MPU scaffolds, such as biodegradation, electroactivity, surface functionalisation, and incorporation of active moieties are also highlighted along with some suggestions for future work.

Ciprofloxacin-Modified Degradable Hybrid Polyurethane-Polylactide Porous Scaffolds Developed for Potential Use as an Antibacterial Scaffold for Regeneration of Skin

The aim of the performed study was to fabricate an antibacterial and degradable scaffold that may be used in the field of skin regeneration. To reach the degradation criterion for the biocompatible polyurethane (PUR), obtained by using amorphous α,ω-dihydroxy(ethylene-butylene adipate) macrodiol (PEBA), was used and processed with so-called "fast-degradable" polymer polylactide (PLA) (5 or 10 wt %). To meet the antibacterial requirement obtained, hybrid PUR-PLA scaffolds (HPPS) were modified with ciprofloxacin (Cipro) (2 or 5 wt %) and the fluoroquinolone antibiotic inhibiting growth of bacteria, such as Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, which are the main causes of wound infections. Performed studies showed that Cipro-modified HPPS, obtained by using 5% of PLA, possess suitable mechanical characteristics, morphology, degradation rates, and demanded antimicrobial properties to be further developed as potential scaffolds for skin tissue engineering.

Fabrication and Characterization of Flexible Medical-Grade TPU Filament for Fused Deposition Modeling 3DP Technology

The possibility of using additive manufacturing (AM) in the medicine area has created new opportunities in health care. This has contributed to a sharp increase in demand for 3D printers, their systems and materials that are adapted to strict medical requirements. We described herein a medical-grade thermoplastic polyurethane (S-TPU) which was developed and then formed into a filament for Fused Deposition Modeling (FDM) 3D printers during a melt-extrusion process. S-TPU consisting of aliphatic hexamethylene 1,6-diisocyanate (HDI), amorphous α,ω-dihydroxy(ethylene-butylene adipate) (PEBA) and 1,4 butandiol (BDO) as a chain extender, was synthesized without the use of a catalyst. The filament (F-TPU) properties were characterized by rheological, mechanical, physico-chemical and in vitro biological properties. The tests showed biocompatibility of the obtained filament as well as revealed no significant effect of the filament formation process on its properties. This study may contribute to expanding the range of medical-grade flexible filaments for standard low-budget FDM printers.

Preparation and Characterization of Graphene Oxide-Modified Sapium sebiferum Oil-Based Polyurethane Composites with Improved Thermal and Mechanical Properties

Bio-based polyurethane (PU) composites with superior thermal and mechanical properties have received wide attention. This is due to the recent rapid developments in the PU industry. In the work reported here, novel nano-composites with graphene oxide (GO)-modified Sapium sebiferum oil (SSO)-based PU has been synthesized via in situ polymerization. GO, prepared using the improved Hummers method from natural graphene (NG), and SSO-based polyol with a hydroxyl value of 211 mg KOH/g, prepared by lipase hydrolysis, were used as raw materials. The microstructures and properties of GO and the nano-composites were both characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile tests. The results showed that GO with its nano-sheet structure possessed a significant number of oxygen-containing functional groups at the surface. The nano-composites containing 1 wt % GO in the PU matrix (PU1) exhibited excellent comprehensive properties. Compared with those for pure PU, the glass transition temperature (Tg) and initial decomposition temperature (IDT) of the PU1 were enhanced by 14.1 and 31.8 °C, respectively. In addition, the tensile strength and Young's modulus of the PU1 were also improved by 126% and 102%, respectively, compared to the pure PU. The significant improvement in both the thermal stability and mechanical properties for PU/GO composites was attributed to the homogeneous dispersion and good compatibility of GO with the PU matrix. The improvement in the properties upon the addition of GO may be attributable to the strong interfacial interaction between the reinforcing agent and the PU matrix.