Scaffold Surface Research Articles

Characterizing properties of scaffolds 3D printed with peptide-polymer conjugates

Three-dimensional (3D) printing is a popular biomaterials fabrication technique because it enables scaffold composition and architecture to be tuned for different applications. Modifying these properties can also alter mechanical properties, making it challenging to decouple biochemical and physical properties. In this study, inks containing peptide-poly(caprolactone) (PCL) conjugates were solvent-cast 3D printed to create peptide-functionalized scaffolds. We characterized how different concentrations of hyaluronic acid-binding (HAbind-PCL) or mineralizing (E3-PCL) conjugates influenced properties of the resulting 3D-printed constructs. The peptide sequences CGGGRYPISRPRKR (HAbind-PCL; positively charged) and CGGGAAAEEE (E3-PCL; negatively charged) enabled us to evaluate how conjugate chemistry, charge, and concentration affected 3D-printed architecture, conjugate location, and mechanical properties. For both HAbind-PCL and E3-PCL, conjugate addition did not affect ink viscosity, filament diameter, scaffold architecture, or scaffold compressive modulus. Increasing conjugate concentration in the ink prior to printing correlated with an increase in peptide concentration on the scaffold surface. Interestingly, conjugate type affected final conjugate location within the 3D-printed filament cross-section. HAbind-PCL conjugates remained within the filament bulk while E3-PCL conjugates were located closer to the filament surface. E3-PCL at all concentrations did not affect mechanical properties, but an intermediate HAbind-PCL concentration resulted in a moderate decrease in filament tensile modulus. These data suggest final conjugate location within the filament bulk may influence mechanical properties. However, no significant differences were observed between PCL filaments printed without conjugates and filaments printed with higher HAbind-PCL concentrations. These results demonstrate that this 3D printing platform can be used to functionalize the surface without significant changes to the physical properties of the scaffold. The downstream potential of this strategy will enable decoupling of biochemical and physical properties to fine-tune cellular responses and support functional tissue regeneration.

Artificial cilia for soft and stable surface covalent immobilization of bone morphogenetic protein-2.

Preservation of growth factor sensitivity and bioactivity (e.g., bone morphogenetic protein-2 (BMP-2)) post-immobilization to tissue engineering scaffolds remains a great challenge. Here, we develop a stable and soft surface modification strategy to address this issue. BMP-2 (a model growth factor) is covalently immobilized onto homogeneous poly (glycidyl methacrylate) (PGMA) polymer brushes which are grafted onto substrate surfaces (Au, quartz glass, silica wafer, or common biomaterials) via surface-initiated atom transfer radical polymerization. This surface modification method multiplies the functionalized interfacial area; it is simple, fast, gentle, and has little effect on the loaded protein owing to the cilia motility. The immobilized BMP-2 (i-BMP-2) on the surface of homogeneous PGMA polymer brushes exhibits excellent bioactivity (⁓87% bioactivity of free BMP-2 in vitro and 20%-50% higher than scaffolds with free BMP-2 in vivo), with conformation and secondary structure well-preserved after covalent immobilization and ethanol sterilization. Moreover, the osteogenic activity of i-BMP-2 on the nanoline pattern (PGMA-poly (N-isopropylacrylamide)) shows ⁓110% bioactivity of free BMP-2. This is superior compared to conventional protein covalent immobilization strategies in terms of both bioactivity preservation and therapeutic efficacy. PGMA polymer brushes can be used to modify surfaces of different tissue-engineered scaffolds, which facilitates in situ immobilization of growth factors, and accelerates repair of a wide range of tissue types.

In vitro and in vivo evaluation of electrospun poly (ε-caprolactone)/collagen scaffolds and Wharton's jelly mesenchymal stromal cells (hWJ-MSCs) constructs as potential alternative for skin tissue engineering

Dermal substitutes bear a high clinical demand because of their ability to promote the healing process of cutaneous wounds by reducing the healing time the appearance and improving the functionality of the repaired tissue. Despite the increasing development of dermal substitutes, most of them are only composed of biological or biosynthetic matrices. This demonstrates the need for new developments focused on using scaffolds with cells (tissue construct) that promote the production of factors for biological signaling, wound coverage, and general support of the tissue repair process. Here, we fabricate by electrospinning two scaffolds: poly(ε-caprolactone) (PCL) as a control and poly(ε-caprolactone)/collagen type I (PCol) in a ratio lower collagen than previously reported, 19:1, respectively. Then, characterize their physicochemical and mechanical properties. As we bear in mind the creation of a biologically functional construct, we characterize and assess in vitro the implications of seeding human Wharton's jelly mesenchymal stromal cells (hWJ-MSCs) on both scaffolds. Finally, to determine the potential functionality of the constructs in vivo, their efficiency was evaluated in a porcine biomodel. Our findings demonstrated that collagen incorporation in the scaffolds produces fibers with similar diameters to those in the human native extracellular matrix, increases wettability, and enhances the presence of nitrogen on the scaffold surface, improving cell adhesion and proliferation. These synthetic scaffolds improved the secretion of factors by hWJ-MSCs involved in skin repair processes such as b-FGF and Angiopoietin I and induced its differentiation towards epithelial lineage, as shown by the increased expression of Involucrin and JUP. In vivo experiments confirmed that lesions treated with the PCol/hWJ-MSCs constructs might reproduce a morphological organization that seems relatively equivalent to normal skin. These results suggest that the PCol/hWJ-MSCs construct is a promising alternative for skin lesions repair in the clinic.

UV-modified and dual-catalytic Cu porphyrin-loaded TiO2 nanotubes with enhanced hemocompatibility and prevention of stent restenosis

Implanting vascular stents is regarded as a ground-breaking technique for treating cardiovascular disorders. Thus, advancements in vascular stent technology and stent materials have significant social and economic implications. The development of a surface with bionic endothelial function of nitric oxide (NO) release is always an ideal direction for cardiovascular material modification. However, The NO-release stents will face severe challenges in the oxidative stress microenvironment of atherosclerotic lesions. Excessive reactive oxygen species (ROS) can delay scaffold surface re-endothelialization by causing rapidly oxidative inactivation of NO and by causing endothelial cells (ECs) to undergo apoptosis. Regulating the oxidative stress microenvironment is crucial to address the aforementioned issues. In this study, a composite material that contains ultraviolet (UV)-modified and Copper (II) meso-tetra(4-carboxyphenyl) porphine (CuTPP)-loaded titanium dioxide nanotubes (NTs) was presented. CuTPP can efficiently catalyze the decomposition of ROS and also decompose GSNO into NO. As a unique technique, UV irradiation was used to enhance the anticoagulant properties of the CuTPP-loaded NTs (NTs@Cu). In vivo and in vitro results demonstrated that UV treated NTs@Cu maintained strong biocompatibility, anti-thrombosis, ECs and smooth muscle cells (SMCs) regulation, and anti-inflammatory capabilities. This technique might present a fresh idea for developing brand-new NO-release scaffolds.

Systematically engineered GO with magnetic CuFe2O4 to enhance bone regeneration on 3D printed PCL scaffold

Composition and processing can profoundly influence the physicomechanical features and cellular function of tissue-engineered scaffolds to regenerate new bone tissue. Here, we developed 3D printed scaffolds containing GO sheets decorated with magnetic CuFe2O4 nanoparticles (NPs). Field emission scanning electron microscopic (FESEM) images depict the formation of high density CuFe2O4 NPs (22 ± 3 nm) uniformly distributed on the surface of GO sheets. Moreover, FESEM images taken from the surface of scaffolds confirm a highly regular structure and desirable printability of the composite material. The incorporation of 8 wt.% GO@CuFe2O4 assist to fabricate PCL-based scaffold with greater mechanical strength (71 ± 0.5 MPa), higher electrical conductivity (2 × 10−8 S/m) and saturation magnetization (1.6 emu/g) as well as better hydrophilicity (74°± 2.4°) than PCL/GO scaffold. Such improvement in physicomechanical properties of the prepared scaffold accelerates pre-osteoblast proliferation, spreading, alkaline phosphatase activity as well as calcium deposition on the scaffold surface and thus, it is an intriguing candidate for useful reconstruction of injured bone tissue.

Evaluation of the Immune Response to Chitosan-graft-poly(caprolactone) Biopolymer Scaffolds.

Biomimetic scaffolds recreating key elements of the architecture and biological activity of the extracellular matrix have enormous potential for soft tissue engineering applications. Combining appropriate mechanical properties with select biological cues presents a challenge for bioengineering, as natural materials are most bioactive but can lack mechanical integrity, while synthetic polymers have strength but are often biologically inert. Blends of synthetic and natural materials, aiming to combine the benefits of each, have shown promise but inherently require a compromise, diluting down favorable properties in each polymer to accommodate the other. Here, we electrospun a material comprising chitosan, a natural polysaccharide, and polycaprolactone (PCL), one of the most widely studied synthetic polymers used in materials engineering. In contrast to a classical blend, here PCL was chemically grafted onto the chitosan backbone to create chitosan-graft-polycaprolactone (CS-g-PCL) and then combined further with unmodified PCL to generate scaffolds with discreet chitosan functionalization. These small amounts of chitosan led to significant changes in scaffold architecture and surface chemistry, reducing the fiber diameter, pore size, and hydrophobicity. Interestingly, all CS-g-PCL-containing blends were stronger than control PCL, though with reduced elongation. In in vitro assessments, increasing the CS-g-PCL content led to significant improvements in in vitro blood compatibility compared to PCL alone while increasing fibroblast attachment and proliferation. In a mouse subcutaneous implantation model, a higher CS-g-PCL content improved the immune response to the implants. Macrophages in tissues surrounding CS-g-PCL scaffolds decreased proportionately to the chitosan content by up to 65%, with a corresponding decrease in pro-inflammatory cytokines. These results suggest that CS-g-PCL is a promising hybrid material comprising natural and synthetic polymers with tailorable mechanical and biological properties, justifying further development and in vivo evaluation.

3D printed solid phase microextraction scaffolds as novel tool for sample preparation; application in antifungal drugs analysis

3D printed solid phase microextraction scaffolds as a novel sorbent were introduced for the extraction of antifungal drugs in wastewater and human plasma prior to their determination by HPLC-UV. The designed adsorbent was prepared as cubic scaffolds using fused deposition modeling (FDM) 3D printer and Polylactic acid (PLA) filament. Scaffold surface was chemically modified using alkaline ammonia solution (Alkali treatment). The application of this new design in the extraction of three antifungal drugs ketoconazole, clotrimazole and miconazole was investigated. Alkali surface modification time was optimized (0.5-5hr) and 4hr selected as the best-modification time. Morphology of the modified surface and its chemical changes were studied using Field Emission Scanning Electron Microscope (FE-SEM) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), respectively. Surface wettability of scaffolds was measured by Water Contact Angel (WCA) and the porosity created in the scaffolds was studied by N2 adsorption/desorption studies analysis. Analytical performance of the method, under optimum conditions (extraction time: 25 min, desorption solvent: methanol, volume of desorption solvent: 2 mL, desorption time: 10 min, solution pH: 8, solution temperature: 40 °C, salt concentration: 3 mol L−1) were obtained as 3.10 and 10.0 µg L−1 for LOD and LOQ, respectively. The calibration graphs were linear in the range of 10–150 µg L−1 and 10-100 µg L−1 for wastewater and plasma, respectively.

3D printing of polylactic acid/boron nitride bone scaffolds: Mechanical properties, biomineralization ability and cell responses

Polylactic acid (PLA) has been widely utilized as a bone scaffold material; however, it exhibits inadequate mechanical performance, biomineralization ability, and cell response, leading to limitations in its practical application. In this study, we utilized boron nitride (BN) nanosheets with favorable mechanical and biological properties to improve the performances of PLA, and prepared PLA/BN composite scaffolds by FDM 3D printing technology. Then, the PLA/BN composite scaffolds with varying BN contents (0–4 wt%) were investigated in terms of microstructure, mechanical performance, biomineralization ability, and cell response. The results showed that the FDM printed PLA/BN scaffolds have an orderly and interconnected porous structure. The mechanical tests showed that the tensile and compression properties (strength and modulus) increased first and then decreased with the content of BN gradually increasing from 0 wt% to 4 wt%, with the optimum mechanical properties occurring at 1 wt%, as an appropriate content of BN could be well-dispersed in the PLA matrix with forming a good interfacial bond, while an excessive content of BN would lead to obvious agglomeration. The simulated body fluid (SBF) soaking experiments showed that BN improved the biomineralization of the PLA scaffold through promoting the formation and deposition of apatite on the scaffold surface by accelerating ion exchange. Besides, an appropriate content of BN promoted the adhesion, proliferation, and osteogenic differentiation of rabbit bone marrow mesenchymal stem cells (BMSCs). These results indicated that BN could be used as a versatile filler for improving the comprehensive performances of polymers, especially for bone tissue engineering.

In Vitro Evaluation of Biphasic Calcium Phosphate Scaffolds Derived from Cuttlefish Bone Coated with Poly(ester urea) for Bone Tissue Regeneration.

This study investigates the osteogenic differentiation of umbilical-cord-derived human mesenchymal stromal cells (hUC-MSCs) on biphasic calcium phosphate (BCP) scaffolds derived from cuttlefish bone doped with metal ions and coated with polymers. First, the in vitro cytocompatibility of the undoped and ion-doped (Sr2+, Mg2+ and/or Zn2+) BCP scaffolds was evaluated for 72 h using Live/Dead staining and viability assays. From these tests, the most promising composition was found to be the BCP scaffold doped with strontium (Sr2+), magnesium (Mg2+) and zinc (Zn2+) (BCP-6Sr2Mg2Zn). Then, samples from the BCP-6Sr2Mg2Zn were coated with poly(ԑ-caprolactone) (PCL) or poly(ester urea) (PEU). The results showed that hUC-MSCs can differentiate into osteoblasts, and hUC-MSCs seeded on the PEU-coated scaffolds proliferated well, adhered to the scaffold surfaces, and enhanced their differentiation capabilities without negative effects on cell proliferation under in vitro conditions. Overall, these results suggest that PEU-coated scaffolds are an alternative to PCL for use in bone regeneration, providing a suitable environment to maximally induce osteogenesis.

3D Printing Process Research and Performance Tests on Sodium Alginate-Xanthan Gum-Hydroxyapatite Hybridcartilage Regenerative Scaffolds.

Cartilage injury is a common occurrence in the modern world. Compared with traditional treatment methods, bio-3D printing technology features better utility in the field of cartilage repair and regeneration, but still faces great challenges. For example, there is currently no means to generate blood vessels inside the scaffolds, and there remains the question of how to improve the biocompatibility of the generated scaffolds, all of which limit the application of bio-3D printing technology in this area. The main objective of this article was to prepare sodium alginate-xanthan gum-hydroxyapatite (SA-XG-HA) porous cartilage scaffolds that can naturally degrade in the human body and be used to promote cartilage damage repair by 3D printing technology. First, the viscosities of SA and XG were analyzed, and their optimal ratio was determined. Second, a mathematical model of the hybrid slurry was established based on the power-law fluid model, in which the printing pressure, needle movement speed, and fiber spacing were established as important parameters affecting the printing performance of the composite. Third, by performing a finite element simulation of the printing process and combining it with the actual printing process, suitable printing parameters were determined (air pressure of 1 bar, moving speed of 9 mm/s, line spacing of 1.6 mm, and adjacent layers of 0-90°). Fourth, composite scaffolds were prepared and tested for their compressive properties, degradation properties, cytotoxicity, and biocompatibility. The results showed that the novel composite scaffolds prepared in this study possessed good mechanical and biological properties. Young's modulus of the composite scaffolds reached 130 KPa and was able to maintain a low degradation rate in simulated body fluid solution for >1 month. The activity of the C5.18 chondrocytes in the scaffold leach solution exceeded 120%. The cells were also able to proliferate densely on the scaffold surface.

GestureSurface: VR Sketching through Assembling Scaffold Surface with Non-Dominant Hand.

3D sketching in virtual reality (VR) provides an immersive drawing experience for designs. However, due to the lack of depth perception cues in VR, scaffolding surfaces that constrain strokes to 2D are usually used as visual guides to reduce the difficulty of drawing accurate strokes. When the dominant hand is occupied by the pen tool, the efficiency of scaffolding-based sketching can be improved by using gesture input to reduce the idleness of the non-dominant hand. This paper presents GestureSurface, a bi-manual interface that uses non-dominant hand performing gestures to operate scaffolding and the other hand drawing with controller. We designed a set of non-dominant gestures to create and manipulate scaffolding surfaces, which are assembled by automatic combination based on five predefined primitive surfaces. We evaluated GestureSurface through a 20-person user study and found that the method of scaffolding-based sketching using non-dominant hand has the advantages of high efficiency and low fatigue.

Fabrication of 3D-printed hydroxyapatite using freeze-drying method for bone regeneration: RVE and finite element simulation analysis

Tissue engineering is an interdisciplinary approach that utilizes cells, scaffolds, and biofactors to develop biosynthetic bone scaffolds for bone regeneration applications. These scaffolds are three-dimensional porous structures with specific mechanical and biological properties that facilitate the attachment and proliferation of osteoinductive cells on their surfaces. In this study, bone scaffolds were 3D-printed using PLA material, and a variety of three-dimensional porous structures, including Kelvin, Octet truss, and Gibson Ashby, were employed. To improve the biological properties of the scaffolds, they were coated with alginate/hydroxyapatite using the Freeze-drying method. The Alginate/HA RVEs were analyzed under periodic boundary conditions, and the elastic modulus was found to improve from 100 MPa (pure alginate) to 149 MPa by adding 30 wt% HA particles. The mechanical properties of the scaffolds were investigated under compressive deformation using experiments and finite element simulations. The results show that the compressive strength of structures follows the order σOctettruss > σGibsonashby > σKelvin. The Freeze-drying process causes pore formation on the scaffold surface. According to the microstructural analysis, the pore size was observed for composite scaffolds approximately at 320–340 μm. After 21-day, most parts of the scaffold surface were coated by the apatite layer completely, and the surface of the pores was blocked by the apatite layer. To characterize cell viability, an MTT assay was used. The scaffolds expose high cell viability around 97% and did not show any significant toxicity.

Surface modifications of scaffolds for bone regeneration

An important strategy in bone tissue engineering is to design and implement biomaterials for the construction of desired scaffolds for the treatment of injuries or fractures. The scaffolds used in bone tissue engineering should have enough strength to withstand the mechanical stress during bone regeneration. However, synthetic or biological polymers used for the fabrication of bone scaffolds do not possess appropriate substrates for an effective material-cell interaction. Consequently, scaffolds are subjected to a variety of physical and chemical post-modifications, and this review discusses only various chemical methods used in post-modifications of scaffolds. Different chemical modifications of scaffolds surfaces are divided into three major categories including plasma surface modification, surface modification with various crosslinking agents and surface functionalization with different functional groups.

Decellularization: Leveraging a Tissue Engineering Technique for Food Production.

The edible nature of many plants makes leaves particularly useful as scaffolds for the development of cultured meat, where animal tissue is grown in the laboratory setting. Recently, we demonstrated that decellularized spinach leaves can serve as scaffolds to grow and differentiate cells for cultured meat products. However, conventional decellularization methods use solutions that are not considered safe for use in food, such as organic solvents (hexanes) and detergents (triton X-100 (TX100)). This study modified decellularization protocols to incorporate detergents that are regulated (REG) by the United States Food and Drug Administration (FDA) for use in food, such as Polysorbate 20 (PS20), and eliminates the use of hexanes for cuticle removal. Spinach leaves were decellularized with sodium dodecyl sulfate and then with either TX100 (control) or PS20. The average DNA content for TX100 samples and PS20 samples was similar (1.3 ± 0.07 vs 1.3 ± 0.05 ng/mg; TX100 vs PS20, p = ns). The importance of cuticle removal was tested by removing hexanes from the protocol. Groups that included the cuticle removal step exhibited an average reduction in DNA content of approximately 91.7%, and groups that omitted the cuticle removal step exhibited an average reduction of approximately 90.3% (p = ns), suggesting that the omission of the cuticle removal step did not impede decellularization. Lastly, primary bovine satellite cells (PBSCs) were cultured for 7 days (d) on the surface of spinach leaves decellularized using the REG protocol. After the 7 d incubation period, PBSCs grown on the surface of REG scaffolds had an average viability of approximately 97.4%. These observations suggest that the REG protocol described in this study is an effective decellularization method, more closely adhering to food safety guidelines, that could be implemented in lab grown meat and alternative protein products.

Proliferation kinetics and mineralization properties of MC3T3‐E1 cells on whey protein isolate scaffolds for bone tissue regeneration

AbstractThe purpose of the study is to assess the influence of scaffold composition and properties on the cellular proliferation and scaffold mineralization on a whey protein isolate (WPI) scaffold. Scaffolds of varying concentrations of WPI, calcium chloride, and amylopectin are seeded with cells, and growth curves are constructed from cell density measurements following incubation. Non‐linear regression yields kinetic growth parameters which are compared for quantitative assessment of scaffold performance. Scaffolds show biocompatibility and the ability to sustain a culture for the length of the study. For up to 14 days, the data are well described by exponential growth. Thereafter, saturation behavior appears, and the data fit well to a sigmoidal model. The seeding efficiency improves with increasing WPI concentration, peaking at 5 mM CaCl2, and decreases with added amylopectin. The growth constant is almost independent of scaffold composition, with possible increases with added CaCl2 and amylopectin. The retardation constant is independent of composition. Scaffolds cultured in differentiation and mineralization conditions, shows development of a mineralized matrix both on acellular scaffold surfaces and in osteoblast cultures. The ability of the unmodified WPI gel surfaces to promote the growth and differentiation of a model preosteoblast provides valuable trends and concentration effects for further scaffold design.

A 3D-Printed Biomaterial Scaffold Reinforced with Inorganic Fillers for Bone Tissue Engineering: In Vitro Assessment and In Vivo Animal Studies.

This research aimed to substantiate the potential practicality of utilizing a matrix-like platform, a novel 3D-printed biomaterial scaffold, to enhance and guide host cells' growth for bone tissue regeneration. The 3D biomaterial scaffold was successfully printed using a 3D Bioplotter® (EnvisionTEC, GmBH) and characterized. Osteoblast-like MG63 cells were utilized to culture the novel printed scaffold over a period of 1, 3, and 7 days. Cell adhesion and surface morphology were examined using scanning electron microscopy (SEM) and optical microscopy, while cell viability was determined using MTS assay and cell proliferation was evaluated using a Leica microsystem (Leica MZ10 F). The 3D-printed biomaterial scaffold exhibited essential biomineral trace elements that are significant for biological bone (e.g., Ca-P) and were confirmed through energy-dispersive X-ray (EDX) analysis. The microscopy analyses revealed that the osteoblast-like MG63 cells were attached to the printed scaffold surface. The viability of cultured cells on the control and printed scaffold increased over time (p < 0.05); however, on respective days (1, 3, and 7 days), the viability of cultured cells between the two groups was not significantly different (p > 0.05). The protein (human BMP-7, also known as growth factor) was successfully attached to the surface of the 3D-printed biomaterial scaffold as an initiator of osteogenesis in the site of the induced bone defect. An in vivo study was conducted to substantiate if the novel printed scaffold properties were engineered adequately to mimic the bone regeneration cascade using an induced rabbit critical-sized nasal bone defect. The novel printed scaffold provided a potential pro-regenerative platform, rich in mechanical, topographical, and biological cues to guide and activate host cells toward functional regeneration. The histological studies revealed that there was progress in new bone formation, especially at week 8 of the study, in all induced bone defects. In conclusion, the protein (human BMP-7)-embedded scaffolds showed higher regenerative bone formation potential (week 8 complete) compared to the scaffolds without protein (e.g., growth factor; BMP-7) and the control (empty defect). At 8 weeks postimplantation, protein (BMP-7) significantly promoted osteogenesis as compared to other groups. The scaffold underwent gradual degradation and replacement by new bones at 8 weeks in most defects.

Vancomycin-loaded silica coatings for controlled release of drug and Si ions to repair infected bone defects

Promoting bone regeneration while inhibiting bacterial infection is still clinical challenge in the repair of infectious bone defects. Herein, a vancomycin-loaded silica coating with controlled release of drug and Si ions was prepared on polymer matrix via layer-by-layer assembly, to construct a functional composite coating scaffold with antibacterial function and enhanced bone regeneration capacity. Different release behavior and antibacterial effect were achieved by alternating or sequential deposition on the scaffold surface. In vitro study showed that both the alternating and the sequential coatings could promote osteogenic differentiation of bone mesenchymal stem cells, and the sequential coating exhibited a higher bacteriostatic rate of 97 % against Staphylococcus aureus. In vivo study of infectious bone defect model demonstrated that the sequential coating with an outer layer of vancomycin allowed more sufficient antibacterial treatment in the early stage of infection and achieved superior bone regeneration consequently. Transcriptomic analysis indicated that the vancomycin loading in the silica coating played an antibacterial role without interfering with the bone-promoting process of silicon ions, and revealed that the mechanism of osteogenic promotion was based on the activation of osteo/angio-genic related genes expression and corresponding signaling pathways. This study demonstrates an effective strategy to design functional composite scaffolds for complex infectious bone repair.

Porous Titanium Scaffold: A New Design for Controlled Drug Delivery

Gelatin crosslinking using conventional methods is usually associated with some toxic side effects. In this research, therefore, the vacuum heating method at 10 Pascal and 140°C under different times of 8, 16, and 32 h was used to cross-link strontium-loaded gelatin microparticles with varying degrees obtained by the oil/water mixing method on titanium scaffolds by the dip-coating method to avoid toxicity and also to control the strontium release rate to the surrounding tissue. The possible phases formed on the surface of the porous titanium scaffolds, the gelatin microparticle distribution, gelatin strontium loading, and strontium release were characterized using thin film X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and inductively coupled plasma-mass spectrometer (ICP-MS) machines, respectively. The results indicated that at 600°C, the rutile phase was formed on the surface of the heat-treated titanium scaffolds. Furthermore, strontium was successfully loaded in the spherical gelatin microparticles, and the strontium-loaded gelatin microparticles were distributed uniformly on the surface of the titanium scaffolds, while the rate of the in vitro strontium release decreased by increasing the time of the gelatin microparticle vacuum-heat crosslinking, whereas at the burst release step, the in vitro strontium release rates were around 5, 4.4, and 2.5 ppm/h, for the 8, 16, and 32 h vacuum-heat cross-linked gelatin microparticles, respectively.

3D printed Sr‐HA/PCL scaffolds: Fabrication via liquid solvent technique

AbstractIn this research, the Sr‐HA/poly(ɛ‐caprolactone) (PCL) composite scaffold was fabricated using a solvent‐based extrusion method. First, the coprecipitation method was used to synthesize the Sr‐HA powders. For this purpose, strontium was doped into hydroxyapatite (HA) with molar ratios of 0%, 2%, 4%, and 6%. Then, the solvent‐based extrusion method was used to manufacture the 3D printed Sr‐HA/PCL scaffolds. X‐ray diffraction analysis, Fourier transform infrared spectrum, and field emission scanning electron microscope of all samples calcined at 900°C for 1 h indicated the formation of a single‐phase HA structure. The composition of the synthesized powders was confirmed using an inductively coupled plasma test and energy‐dispersive X‐ray spectroscopy. The compressive strength of Sr‐HA/PCL scaffolds compared with pure HA increased from 3.8 to 5.9 MPa. Results of the MTT test showed that Sr‐HA/PCL scaffolds were biocompatible and the growth and proliferation of MG63 cells on the surface of scaffolds increased with the presence of strontium.

CO-CULTURE OF MESENCHYMAL STROMAL CELLS AND LIGAMENTOCYTES ON TRIPHASIC EMBROIDERED SCAFFOLDS FOR ANTERIOR CRUCIATE LIGAMENT ENTHESIS TISSUE ENGINEERING

Successful anterior cruciate ligament (ACL) reconstructions strive a firm ligament-bone integration. Therefore, the aim of this study was to address in more detail the enthesis as the thriphasic bone attachment of the ACL using a tissue engineering approach. To establish a tissue-engineered enthesis-like construct, triphasic scaffolds embroidered from poly(L-lactide-co-caprolactone) and polylactic acid functionalized with collagen foam were colonized with osteogenically differentiated human mesenchymal stromal cells (hMSCs) and lapine (L) ACL fibroblasts.These triphasic scaffolds with a bone-, a fibrocartilage transition- and a ligament phase were seeded directly after spheroid assembly or with 14 days precultured LACL fibroblast spheroids and 14 days osteogenically differentiated hMSCs spheroids (=longer preculture) and cultured for further 14 days. Cell survival was tested. Collagen type I and vimentin were immunolabeled and the content of DNA and sulfated glycosaminoglycan (sGAG) was quantified. The relative gene expression of tenascin C, type I and X collagens, Mohawk and Runx2 was analyzed.Compared to the LACL spheroids the hMSC spheroids adhered better to the scaffold surface with faster cell outgrowth on the fibers. Collagen type I and vimentin were mainly detected in the hMSCs colonizing the bone zone. The DNA content was generally higher in the bone (hMSCs) than in the ligament zones and after short spheroid preculture higher than after longer preculture whereas the sGAG content was greater after longer preculture for both cell types. The longer precultivated hMSCs expressed more type I collagen in comparison to those only shortly precultured before scaffold seeding. Type I collagen and tenascin C were higher expressed in scaffolds directly colonized with LACL compared to those seeded after longer spheroid preculture. The gene expression of ECM components and transcription factors depended on cell type and preculturing condition.Zonal colonization of triphasic scaffolds using the spheroid method is possible offering a novel approach for enthesis tissue engineering.