Tissue Scaffolds Research Articles

Magnetic carbon nanotubes modified with proteins and hydrophilic monomers: Cytocompatibility, in-vitro toxicity assays and permeation across biological interfaces

Carbon nanotubes are promising materials for biomedical applications like delivery systems and tissue scaffolds. In this paper, magnetic carbon nanotubes (M-CNTs) covered with bovine serum albumin (M-CNTs-BSA) or functionalized with hydrophilic monomers (M-CNTs-HL) were synthesized, characterized, and evaluated concerning their interaction with Caco-2 cells. There is no comparison between these two types of functionalization, and this study aimed to verify their influence on the material's interaction with the cells. Different concentrations of the nanotubes were applied to investigate cytotoxicity, cell metabolism, oxidative stress, apoptosis, and capability to cross biomimetic barriers. The materials showed cytocompatibility up to 100 μg mL−1 and a hemolysis rate below 2 %. Nanotubes' suspensions were allowed to permeate Caco-2 monolayers for up to 8 h under the effect of the magnetic field. Magnetic nanoparticles associated with the nanotubes allowed estimation of permeation through the monolayers, with values ranging from 0.50 to 7.19 and 0.27 to 9.30 × 10−3 μg (equivalent to 0.43 to 6.22 and 0.23 to 9.54 × 10−2 % of the initially estimated mass of magnetic nanoparticles) for cells exposed and non-exposed to the magnets, respectively. Together, these results support that the developed materials are promising for applications in biomedical and biotechnological fields.

Computational fluid dynamics analysis of the fluid environment of 3D printed gradient structure in interfacial tissue engineering

Mass transport properties within three-dimensional (3D) scaffold are essential for tissue regeneration, such as various fluid environmental cues influence mesenchymal stem cells differentiation. Recently, 3D printing has been emerging as a new technology for scaffold fabrication by controlling the scaffold pore geometry to affect cell growth environment. In this study, the flow field within scaffolds in a perfusion system was investigated with uniform structures, single gradient structures and complex gradient structures using computational fluid dynamics (CFD) method. The CFD results from those uniform structures indicate the fluid velocity and fluid shear stress within the scaffold structure increased as the filament diameter increasing, pore width decreasing, pore shape decreased from 90° to 15°, and layer configuration changing from lattice to stagger structure. By assembling those uniform structure as single gradient structures, it is noted that the fluid dynamic characterisation within the scaffold remains the same as the corresponding uniform structures. A complex gradient structure was designed to mimic natural osteochondral tissue by assembly the uniform structures of filament diameter, pore width, pore shape and layer configuration. The results show that the fluid velocity and fluid shear stress within the complex gradient structure distribute gradually increasing and their maximum magnitude were from 1.15 to 3.20 mm/s, and from 12 to 39 mPa, respectively. CFD technique allows the prediction of velocity and fluid shear stress within the designed 3D gradient scaffolds, which would be beneficial for the tissue scaffold development for interfacial tissue engineering in the future.

Architectural differences in photopolymerized PEG-based thiol-acrylate hydrogels enable enhanced mechanical properties and 3D printability

Hydrogels have been widely investigated for applications in the human body due to their tunability and biocompatibility. Nevertheless, their application is still limited by their relatively low mechanical strength relative to load-bearing tissue scaffolds like articular cartilage. In this work, we synthesized hydrogels by combining linear poly(ethylene glycol) dimethacrylate (PEGDMA) with a 3-arm-PEG end-functionalized with thiol. We demonstrate that the combination of thiol-ene click chemistry with a multifunctional crosslinker reduces the crosslink and entanglement density in comparison with the otherwise statistically crosslinked/polymerized PEGDMA, whereby the only viable mode of gelation is through radical propagation or termination at the double bond. The corresponding minimization of topological heterogeneities that arises during thiol-ene crosslinking results in hydrogels with compressive strength in the range of tens of MPa. The molar mass of the linear PEGDMA precursor is readily tunable, unlocking access to a wider range of mechanical properties. We employed photo-mediated crosslinking protocol, which is amenable to advanced processing technologies such as light-based 3D printing techniques. Such advanced fabrication processes offer high precision and control during the generation of customizable macroscopic objects. Simple prototypes were generated using digital light processing (DLP) equipment. We demonstrate that integrating a simple co-macromonomer into a widely employed hydrogel platform can unlock new mechanical regimes and mitigate the inherent brittleness associated with these materials. The simplicity of this approach, coupled with its easy tunability and adaptability to light-based techniques, holds promise for broadening hydrogel applications in tissue engineering. Our findings contribute to advancing materials and methodologies, facilitating enhanced design and fabrication of functional constructs.

Unveiling In situ fibrillation for superior tissue scaffolds with two-phase copolymer microcellular foams

High open-pore content and high mechanical strength are important in Tissue engineering. However, an increase in one property is often at the expense of the other. This study reports a first-of-its-kind study using two-phase copolymers Poly (caprolactone-co-lactic acid) (PLCL) as a compatibilizer, combining in-situ fibrillation and microcellular foaming, thus preparing foams with high open-pore content and high mechanical properties. The porous foam scaffold promotes the adhesion and diffusion of endothelial cells and expedites scaffold endothelialization. Additionally, the enhanced open porosity of the foams augments the effectiveness of drug absorption and release, underscoring its significant potential for practical application.

Unraveling the influence of channel size and shape in 3D printed ceramic scaffolds on osteogenesis

Bone has the capacity to regenerate itself for relatively small defects; however, this regenerative capacity is diminished in critical-size bone defects. The development of synthetic materials has risen as a distinct strategy to address this challenge. Effective synthetic materials to have emerged in recent years are bioceramic implants, which are biocompatible and highly bioactive. Yet nothing suitable for the repair of large bone defects has made the transition from laboratory to clinic. The clinical success of bioceramics has been shown to depend not only on the scaffold's intrinsic material properties but also on its internal porous geometry. This study aimed to systematically explore the implications of varying channel size, shape, and curvature in tissue scaffolds on in vivo bone regeneration outcomes. 3D printed bioceramic scaffolds with varying channel sizes (0.3 mm to 1.5 mm), shapes (circular vs rectangular), and curvatures (concave vs convex) were implanted in rabbit femoral defects for 8 weeks, followed by histological evaluation. We demonstrated that circular channel sizes of around 0.9 mm diameter significantly enhanced bone formation, compared to channel with diameters of 0.3 mm and 1.5 mm. Interestingly, varying channel shapes (rectangular vs circular) had no significant effect on the volume of newly formed bone. Furthermore, the present study systematically demonstrated the beneficial effect of concave surfaces on bone tissue growth in vivo, reinforcing previous in silico and in vitro findings. This study demonstrates that optimizing architectural configurations within ceramic scaffolds is crucial in enhancing bone regeneration outcomes. Statement of significanceDespite the explosion of work on developing synthetic scaffolds to repair bone defects, the amount of new bone formed by scaffolds in vivo remains suboptimal. Recent studies have illuminated the pivotal role of scaffolds’ internal architecture in osteogenesis. However, these investigations have mostly remained confined to in silico and in vitro experiments. Among the in vivo studies conducted, there has been a lack of systematic analysis of individual architectural features. Herein, we utilized bioceramic 3D printing to conduct a systematic exploration of the effects of channel size, shape, and curvature on bone formation in vivo. Our results demonstrate the significant influence of channel size and curvature on in vivo outcomes. These findings provide invaluable insights into the design of more effective bone scaffolds.

3D Poly (L-lactic acid) fibrous sponge with interconnected porous structure for bone tissue scaffold

Large bone defects, often resulting from trauma and disease, present significant clinical challenges. Electrospun fibrous scaffolds closely resembling the morphology and structure of natural ECM are highly interested in bone tissue engineering. However, the traditional electrospun fibrous scaffold has some limitations, including lacking interconnected macropores and behaving as a 2D scaffold. To address these challenges, a sponge-like electrospun poly(L-lactic acid) (PLLA)/polycaprolactone (PCL) fibrous scaffold has been developed by an innovative and convenient method (i.e., electrospinning, homogenization, progen leaching and shaping). The resulting scaffold exhibited a highly porous structure (overall porosity = 85.9 %) with interconnected, regular macropores, mimicking the natural extracellular matrix. Moreover, the incorporation of bioactive glass (BG) particles improved the hydrophilicity (water contact angle = 79.7°) and biocompatibility and promoted osteoblast cell growth. In-vitro 10-day experiment revealed that the scaffolds led to high cell viability. The increment of the proliferation rates was 195.4 % at day 7 and 281.6 % at day 10. More importantly, Saos-2 cells could grow, proliferate, and infiltrate into the scaffold. Therefore, this 3D PLLA/PCL with BG sponge holds great promise for bone defect repair in tissue engineering applications.

SPINNED: Simulation-based physics-informed neural network for deconvolution of dynamic susceptibility contrast MRI perfusion data.

To propose the simulation-based physics-informed neural network for deconvolution of dynamic susceptibility contrast (DSC) MRI (SPINNED) as an alternative for more robust and accurate deconvolution compared to existing methods. The SPINNED method was developed by generating synthetic tissue residue functions and arterial input functions through mathematical simulations and by using them to create synthetic DSC MRI time series. The SPINNED model was trained using these simulated data to learn the underlying physical relation (deconvolution) between the DSC-MRI time series and the arterial input functions. The accuracy and robustness of the proposed SPINNED method were assessed by comparing it with two common deconvolution methods in DSC MRI data analysis, circulant singular value decomposition, and Volterra singular value decomposition, using both simulation data and real patient data. The proposed SPINNED method was more accurate than the conventional methods across all SNR levels and showed better robustness against noise in both simulation and real patient data. The SPINNED method also showed much faster processing speed than the conventional methods. These results support that the proposed SPINNED method can be a good alternative to the existing methods for resolving the deconvolution problem in DSC MRI. The proposed method does not require any separate ground-truth measurement for training and offers additional benefits of quick processing time and coverage of diverse clinical scenarios. Consequently, it will contribute to more reliable, accurate, and rapid diagnoses in clinical applications compared with the previous methods including those based on supervised learning.

The Combination of Bioactive Herbal Compounds with Biomaterials for Regenerative Medicine.

Regenerative medicine aims to restore the function of diseased or damaged tissues and organs by cell therapy, gene therapy, and tissue engineering, along with the adjunctive application of bioactive molecules. Traditional bioactive molecules, such as growth factors and cytokines, have shown great potential in the regulation of cellular and tissue behavior, but have the disadvantages of limited source, high cost, short half-life, and side effects. In recent years, herbal compounds extracted from natural plants/herbs have gained increasing attention. This is not only because herbal compounds are easily obtained, inexpensive, mostly safe, and reliable, but also owing to their excellent effects, including anti-inflammatory, antibacterial, antioxidative, proangiogenic behavior and ability to promote stem cell differentiation. Such effects also play important roles in the processes related to tissue regeneration. Furthermore, the moieties of the herbal compounds can form physical or chemical bonds with the scaffolds, which contributes to improved mechanical strength and stability of the scaffolds. Thus, the incorporation of herbal compounds as bioactive molecules in biomaterials is a promising direction for future regenerative medicine applications. Herein, an overview on the use of bioactive herbal compounds combined with different biomaterial scaffolds for regenerative medicine application is presented. We first introduce the classification, structures, and properties of different herbal bioactive components and then provide a comprehensive survey on the use of bioactive herbal compounds to engineer scaffolds for tissue repair/regeneration of skin, cartilage, bone, neural, and heart tissues. Finally, we highlight the challenges and prospects for the future development of herbal scaffolds toward clinical translation. Overall, it is believed that the combination of bioactive herbal compounds with biomaterials could be a promising perspective for the next generation of regenerative medicine.

Preparation of thiolated poly (lactic acid) microspheres by amine ester reaction to simulate three-dimensional inkjet printing (3DP) biocompatible scaffolds

3D inkjet printing (3DP) technology offers the advantages of fast processing speed and high precision, but achieving a strong combination of “powder” and “ink“ in polymer materials remains a great challenge. In this work, thiolated poly(lactic acid) (PLA) microspheres are fabricated through the amine-ester reaction between cysteine and PLA in a “green” water environment. 3DP is then simulated using thiolated PLA microspheres as the “powder”, and acryloylmorpholine containing double bonds as the “ink”. By virtue of the fast “thiol-ene click” reaction, the PLA scaffolds with a covalent bonding interface are fabricated within 20 s. Both the thiolated microspheres and scaffolds exhibit good biocompatibility, and the tensile strength of the scaffolds can reach 13.2 MPa, with the Young's modulus of 722 MPa, meeting the performance requirements of bone tissue scaffolds. Therefore, a new strategy to solve the interfacial bonding problem in 3DP technology are provided, facilitating the 3DP molding of PLA powder and promoting its application in the field of life and health.

EXPANDING HORIZONS: DIVERSE APPLICATIONS OF RUBBERS AND ELASTOMERS IN EMERGING TECHNOLOGIES

ABSTRACT Rubbers and elastomers have a rich history that spans many eras of human civilization dating back to 1600 AD. Upon their introduction into Europe, they became common materials in shoes and fabrics. With the invention of vulcanization by Charles Goodyear in 1839, rubbers became widely used in many new applications, ranging from tires to industrial machine parts. Today, rubbers and elastomers are essential in the development of innovative, emerging technologies. This review exemplifies how rubbers and elastomers have been used to advance the emerging fields of soft robotics through soft grippers and dielectric elastomer actuators, stretchable and wearable devices through conductive elastomers and smart elastomers used in thermal camouflage and sensors, biomedical applications through tissue scaffolding and stretch-triggered drug delivery, and energy harvesting through piezoelectric elastomers and wave harvesting triboelectric nanogenerators. This review also briefly summarizes other developments in these fields as well as glimpses into other emerging fields that are advancing through the incorporation of rubbers and elastomers.

Adipose tissue reconstruction facilitated with low immunogenicity decellularized adipose tissue scaffolds.

There is currently an urgent need to develop engineered scaffolds to support new adipose tissue formation and facilitate long-term maintenance of function and defect repair to further generate prospective bioactive filler materials capable of fulfilling surgical needs. Herein, adipose regeneration methods were optimized and decellularized adipose tissue (DAT) scaffolds with good biocompatibility were fabricated. Adipose-like tissues were reconstructed using the DAT and 3T3-L1 preadipocytes, which have certain differentiation potential, and the regenerative effects of the engineered adipose tissuesin vitroandin vivowere explored. The method improved the efficiency of adipose removal from tissues, and significantly shortened the time for degreasing. Thus, the DAT not only provided a suitable space for cell growth but also promoted the proliferation, migration, and differentiation of preadipocytes within it. Following implantation of the constructed adipose tissuesin vivo, the DAT showed gradual degradation and integration with surrounding tissues, accompanied by the generation of new adipose tissue analogs. Overall, the combination of adipose-derived extracellular matrix and preadipocytes for adipose tissue reconstruction will be of benefit in the artificial construction of biomimetic implant structures for adipose tissue reconstruction, providing a practical guideline for the initial integration of adipose tissue engineering into clinical medicine.

Investigation of Liquid Collagen Ink for Three-Dimensional Printing.

Three-dimensional printing provides more versatility in the fabrication of scaffold materials for hard and soft tissue replacement, but a critical component is the ink. The ink solution should be biocompatible, stable, and able to maintain scaffold shape, size, and function once printed. This paper describes the development of a collagen ink that remains in a liquid pre-fibrillized state prior to printing. The liquid stability occurs due to the incorporation of ethylenediaminetetraacetic acid (EDTA) during dialysis of the collagen. Collagen inks were 3D-printed using two different printers. The resulting scaffolds were further processed using two different chemical crosslinkers, 1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride)/N-hydroxysuccinimide (EDC/NHS) and genipin; gold nanoparticles were conjugated to the scaffolds. The 3D-printed scaffolds were characterized to determine their extrudability, stability, amount of AuNP conjugated, and overall biocompatibility via cell culture studies using fibroblast cells and stroma cells. The results demonstrated that the liquid collagen ink was amendable to 3D printing and was able to maintain its 3D shape. The scaffolds could be conjugated with gold nanoparticles and demonstrated enhanced biocompatibility. It was concluded that the liquid collagen ink is a good candidate material for the 3D printing of tissue scaffolds.

3D printed Nanohydroxyapatite/Polyamide 66 scaffolds with balanced mechanical property and osteogenic ability for bone repair

The biomaterial requirements for bone tissue repair are extremely strict. It not only requires the biomaterial to have good biocompatibility and biological activity, but also requires sufficient mechanical strength. Polyamide 66 (PA66) and nano-hydroxyapatite (n-HA) have been widely investigated in bone tissue engineering scaffold, however, its composites require further research. In this study, the 3D printing technology was utilized to fabricate personalized n-HA/PA66 bone tissue scaffold. The mechanical properties of n-HA/PA66 composite can be adjusted by configuring different raw material components and applying different porosity. It was found that 50 % porosity n-HA/PA66 composite scaffold showed a uniform porous structure and a compressive strength of 33.9 MPa. The composite scaffold also exhibited excellent biological properties while improving mechanical properties, in vitro cell tests indicated that the 3D printed n-HA/PA66 composite scaffold promoted differentiation of bone marrow mesenchymal stem cells (BMSCs) into osteoblasts. In in vivo animal model proved that the scaffold promoted endogenous bone regeneration in rabbit patellar bone defects, with newly formed bone volume of 20.9 % after two months of implantation. This research proposed a 3D printed polyamide/nano-hydroxyapatite composite with balanced mechanical property and osteogenic ability for customized bone tissue repair, and it has promising application prospects.

Influence of Breath-Mimicking Ventilated Incubation on Three-Dimensional Bioprinted Respiratory Tissue Scaffolds.

Development of respiratory tissue constructs is challenging due to the complex structure of native respiratory tissue and the unique biomechanical conditions induced by breathing. While studies have shown that the inclusion of biomechanical stimulus mimicking physiological conditions greatly benefits the development of engineered tissues, to our knowledge no studies investigating the influence of biomechanical stimulus on the development of respiratory tissue models produced through three-dimensional (3D) bioprinting have been reported. This paper presents a study on the utilization of a novel breath-mimicking ventilated incubator to impart biomechanical stimulus during the culture of 3D respiratory bioprinted constructs. Constructs were bioprinted using an alginate/collagen hydrogel containing human primary pulmonary fibroblasts with further seeding of human primary bronchial epithelial cells. Biomechanical stimulus was then applied via a novel ventilated incubator capable of mimicking the pressure and airflow conditions of multiple breathing conditions: standard incubation, shallow breathing, normal breathing, and heavy breathing, over a two-week time period. At time points between 1 and 14 days, constructs were characterized in terms of mechanical properties, cell proliferation, and morphology. The results illustrated that incubation conditions mimicking normal and heavy breathing led to greater and more continuous cell proliferation and further indicated a more physiologically relevant respiratory tissue model.

Synthesis of Alginate/Collagen Bioink for Bioprinting Respiratory Tissue Models.

Synthesis of bioinks for bioprinting of respiratory tissue requires considerations related to immunogenicity, mechanical properties, printability, and cellular compatibility. Biomaterials can be tailored to provide the appropriate combination of these properties through the synergy of materials with individual pros and cons. Sodium alginate, a water-soluble polymer derived from seaweed, is a cheap yet printable biomaterial with good structural properties; however, it lacks physiological relevance and cell binding sites. Collagen, a common component in the extra cellular matrix of many tissues, is expensive and lacks printability; however, it is highly biocompatible and exhibits sites for cellular binding. This paper presents our study on the synthesis of bioinks from alginate and collagen for use in bioprinting respiratory tissue models. Bioinks were synthesized from 40 mg/mL (4%) alginate and 3 mg/mL (0.3%) collagen in varying ratios (1:0, 4:1, 3:1, 2:1, and 1:1); then examined in terms of rheological properties, printability, compressive, and tensile properties and cellular compatibility. The results illustrate that the ratio of alginate to collagen has a profound impact on bioink performance and that, among the examined ratios, the 3:1 ratio is the most appropriate for use in bioprinting respiratory tissue scaffolds.

The development of a modular and open-source multi-head 3D bioprinter for fabricating complex structures

Various 3D bioprinting techniques have been introduced and developed to fabricate biomimetic constructs based on biomaterials or cell-laden bioinks to create functionally engineered tissues or organs for tissue engineering applications. However, single-biomaterial printing techniques often fail to replicate the intricate compositions and diversity found in native tissues. Multi-bioinks or multi-biomaterials in bioprinting can be utilized through either a single printhead or multiple separate printheads. However, the cost of commercially available multi-heads for bioprinting is prohibitively high, hindering their application in tissue engineering endeavors. Additionally, each bioink or biomaterial possesses unique printing characteristics that are best suited for specific printing techniques. The current study presents the development of a modular and cost-effective dual-head position bioprinter based on an open-source approach using Marlin firmware. The highlighted features of the 3D bioprinter include the use of various power sources such as compressed air and electricity for the printheads, the integration of a movable printhead mechanism with a wiper arm to prevent collisions with large printed samples during printing, a printhead adapter, as well as nozzle kits designed in a modular form for easy replacement for specific bio-applications. Therefore, despite the presence of two positions to mount the printheads, the custom-designed bioprinter exhibits the capability to flexibly accommodate four distinct printhead modules and three modular nozzle kits to print various biomaterials, such as polycaprolactone (PCL) and its composites with sodium alginate (SA), tricalcium phosphate (TCP) and hydrogel mixtures including SA, gelatin (GL), and k-carrageenan (κ-Carr). Complex tissue scaffolds were successfully fabricated using multi-biomaterials to showcase the versatility of the bioprinter, thereby demonstrating its potential for a wide range of tissue engineering applications.

Plant Decellularization by Chemical and Physical Methods for Regenerative Medicine: A Review Article.

Fabricating three-dimensional (3D) scaffolds is attractive due to various advantages for tissue engineering, such as cell migration, proliferation, and adhesion. Since cell growth depends on transmitting nutrients and cell residues, naturally vascularized scaffolds are superior for tissue engineering. Vascular passages help the inflow and outflow of liquids, nutrients, and waste disposal from the scaffold and cell growth. Porous scaffolds can be prepared by plant tissue decellularization which allows for the cultivation of various cell lines depending on the intended application. To this end, researchers decellularize plant tissues by specific chemical and physical methods. Researchers use plant parts depending on their needs, for example, decellularizing the leaves, stems, and fruits. Plant tissue scaffolds are advantageous for regenerative medicine, wound healing, and bioprinting. Studies have examined various plants such as vegetables and fruits such as orchid, parsley, spinach, celery, carrot, and apple using various materials and techniques such as sodium dodecyl sulfate, Triton X-100, peracetic acid, deoxyribonuclease, and ribonuclease with varying percentages, as well as mechanical and physical techniques like freeze-thaw cycles. The process of data selection, retrieval, and extraction in this review relied on scholarly journal publications and other relevant papers related to the subject of decellularization, with a specific emphasis on plant-based research. The obtained results indicate that, owing to the cellulosic structure and vascular nature of the decellularized plants and their favorable hydrophilic and biological properties, they have the potential to serve as biological materials and natural scaffolds for the development of 3D-printing inks and scaffolds for tissue engineering.

63 Allogeneic Recellularized Lung Orthotopic (ARLO) Transplant Research

OBJECTIVES/GOALS: As of 2021, the lung transplantation waiting list has a mortality rate of 7.6 deaths per 100 patient-years. Bioengineered human organs is an emerging field of tissue engineering with a goal of developing suitable organs for transplantation. The focus of the project is to evaluate the efficacy of bioengineered lungs using a human-to-swine model. METHODS/STUDY POPULATION: This project will involve designing and assessing the bioengineered lung by establishing a human-to-pig xenotransplantation survival model. The project aims to evaluate how well the bioengineered lung functions within a living model. The bioengineered lung is constructed using swine connective tissue scaffolding, which has been recellularized with human cells. Anatomically, the lung will resemble a swine lung but will possess the immunological and cellular markers of human tissue. The proposed model will initially assess the immunological response of swine to human lung tissue. Lung function will be assessed during surgery using pulmonary vein gas samples and tissue sampling. Following the end of the study, additional tissues samples will be taken to evaluate the immunological response to the tissue. RESULTS/ANTICIPATED RESULTS: Xenotransplantation and bioengineered organs are two new emerging fields of research that have just begun to enter the large animal testing phase. This model will provide a novel human-to-pig xenotransplant survival model that will be used to test the efficacy of bioengineered lungs function in a dynamic living organism. The design has taken the principles of immunology learned from the current clinical and xenotransplant research and has incorporated this knowledge into the known pig-to-pig transplant models. We anticipate that this model design will be easily reproducible and can be expanded to other bioengineered organs as an effective means to test functionality. DISCUSSION/SIGNIFICANCE: The COVID-19 pandemic’s aftermath may lead to an increased demand for lung transplants. Bioengineered lungs could provide an additional source of organs to supplement current availability. This novel approach has the potential to offer a means to test several different types of bioengineered organs in the future.

Polyvinyl alcohol: Starch based membrane scaffolds for tissue transparency requirements: Fabrication, characterization and cytotoxicity studies

In this study, the characterization and cytocompatibility of polyvinyl alcohol:starch (PVA:ST) based membrane tissue scaffolds developed for tissue transparency requirements in tissue engineering applications were evaluated in the presence of sodium dodecyl sulphate (SDS). In this context, two different amounts of SDS were added to the polymer structure of transparent membrane scaffolds to roughen the surfaces of PVA:ST membranes and to promote cell adhesion. In the light of this aim, three different types of membranes were created: A constant PVA:ST ratio of 9:1 (wt:wt) was used as a control and varying amounts of SDS (2 and 4 wt% of the total polymer amount) were added to the polymer solutions. Membrane tissue scaffolds were formed by freeze-drying method. Scaffold properties such as morphology, transparency, water absorption, chemical structure and cytocompatibility were investigated. In terms of physicochemical properties, it was observed that with the addition of SDS, the membranes had a rougher surface while retaining water retention and transparency. In cytotoxicity studies, the membranes were found to be non-cytotoxic and promoted cell proliferation as assessed by MTT assay. Furthermore, the PVA:ST membrane scaffold with 4% SDS added was able to promote the attachment, migration and proliferation of Mouse Embryonic Fibroblasts (MEFs) more than the control group. Overall, the results indicate that SDS-added PVA:ST scaffold membranes are suitable for human corneal stromal regeneration, wound dressing material and neural tissue engineering applications.

Porous Mg–Zn–Ca scaffolds for bone repair: a study on microstructure, mechanical properties and in vitro degradation behavior

Biodegradable porous Mg scaffolds are a promising approach to bone repair. In this work, 3D-spherical porous Mg–1.5Zn–0.2Ca (wt.%) scaffolds were prepared by vacuum infiltration casting technology, and MgF2 and fluorapatite coatings were designed to control the degradation behavior of Mg-based scaffolds. The results showed that the pores in Mg-based scaffolds were composed of the main spherical pores (450–600 μm) and interconnected pores (150–200 μm), and the porosity was up to 74.97%. Mg-based porous scaffolds exhibited sufficient mechanical properties with a compressive yield strength of about 4.04 MPa and elastic modulus of appropriately 0.23 GPa. Besides, both MgF2 coating and fluorapatite coating could effectively improve the corrosion resistance of porous Mg-based scaffolds. In conclusion, this research would provide data support and theoretical guidance for the application of biodegradable porous Mg-based scaffolds in bone tissue engineering.Graphical