Architecture of β-Lactoglobulin Coating Modulates Bioinspired Alginate Dialdehyde-Gelatine/Polydopamine Scaffolds for Subchondral Bone Regeneration

In this study, we developed polydopamine (PDA)-functionalized alginate dialdehyde-gelatine (ADA-GEL) scaffolds for subchondral bone regeneration. These polymeric scaffolds were then coated with β-Lactoglobulin (β-LG) at concentrations of 1 mg/ml and 2 mg/ml. Morphological analysis indicated a homogeneous coating of the β-LG layer on the surface of network-like scaffolds. The β-LG-coated scaffolds exhibited improved swelling capacity as a function of the β-LG concentration. Compared to ADA-GEL/PDA scaffolds, the β-LG-coated scaffolds demonstrated delayed degradation and enhanced biomineralization. Here, a lower concentration of β-LG showed long-lasting stability and superior biomimetic hydroxyapatite mineralization. According to the theoretical findings, the single-state, representing the low concentration of β-LG, exhibited homogeneous distribution on the surface of the PDA, while the dimer-state (high concentration) displayed a high likelihood of uncontrolled interactions. β-LG-coated ADA-GEL/PDA scaffolds with a lower concentration of β-LG provided a biocompatible substrate that supported adhesion, proliferation, and alkaline phosphatase (ALP) secretion of sheep bone marrow mesenchymal stem cells, as well as increased expression of osteopontin (SPP1) and collagen type 1 (COL1A1) in human osteoblasts. These findings indicate the potential of protein-coated scaffolds for subchondral bone tissue regeneration. STATEMENT OF SIGNIFICANCE: This study addresses a crucial aspect of osteochondral defect repair, emphasizing the pivotal role of subchondral bone regeneration. The development of polydopamine-functionalized alginate dialdehyde-gelatine (ADA-GEL) scaffolds, coated with β-Lactoglobulin (β-LG), represents a novel approach to potentially enhance subchondral bone repair. β-LG, a milk protein rich in essential amino acids and bioactive peptides, is investigated for its potential to promote subchondral bone regeneration. This research explores computationally and experimentally the influence of protein concentration on the ordered or irregular deposition, unravelling the interplay between coating structure, scaffold properties, and in-vitro performance. This work contributes to advancing ordered protein coating strategies for subchondral bone regeneration, providing a biocompatible solution with potential implications for supporting subsequent cartilage repair.

Bovine serum albumin-modified 3D printed alginate dialdehyde-gelatin scaffolds incorporating polydopamine/SiO2-CaO nanoparticles for bone regeneration

Three-dimensional (3D) printing allows precise manufacturing of bone scaffolds for patient-specific applications and is one of the most recently developed and implemented technologies. In this study, bilayer and multimaterial alginate dialdehyde-gelatin (ADA-GEL) scaffolds incorporating polydopamine (PDA)/SiO2-CaO nanoparticle complexes were 3D printed using a pneumatic extrusion-based 3D printing technology and further modified on the surface with bovine serum albumin (BSA) for application in bone regeneration. The morphology, chemistry, and in vitro bioactivity of PDA/SiO2-CaO nanoparticle complexes were characterized (n = 3) and compared with those of mesoporous SiO2-CaO nanoparticles. Successful deposition of the PDA layer on the surface of the SiO2-CaO nanoparticles allowed better dispersion in a liquid medium and showed enhanced bioactivity. Rheological studies (n = 3) of ADA-GEL inks consisting of PDA/SiO2-CaO nanoparticle complexes showed results that may indicate better injectability and printability behavior compared to ADA-GEL inks incorporating unmodified nanoparticles. Microscopic observations of 3D printed scaffolds revealed that PDA/SiO2-CaO nanoparticle complexes introduced additional topography onto the surface of 3D printed scaffolds. Additionally, the modified scaffolds were mechanically stable and elastic, closely mimicking the properties of natural bone. Furthermore, protein-coated bilayer scaffolds displayed controllable absorption and biodegradation, enhanced bioactivity, MC3T3-E1 cell adhesion, proliferation, and higher alkaline phosphatase (ALP) activity (n = 3) compared to unmodified scaffolds. Consequently, the present results confirm that ADA-GEL scaffolds incorporating PDA/SiO2-CaO nanoparticle complexes modified with BSA offer a promising approach for bone regeneration applications.

Biosynthesis of Zinc Oxide Nanoparticles on l-Carnosine Biofunctionalized Polyacrylonitrile Nanofibers; a Biomimetic Wound Healing Material

Multifunctional biohybrid nanofibers (NFs) that can simultaneously drive various cellular activities and confer antibacterial properties are considered desirable in producing advanced wound healing materials. In this study, a bionanohybrid formulation was processed as a NF wound dressing to stimulate the adhesion and proliferation of fibroblast and endothelial cells that play a major role in wound healing. Polyacrylonitrile (PAN) electrospun NFs were hydrolyzed using NaOH and biofunctionalized with l-carnosine (CAR), a dipeptide which could later biosynthesize zinc oxide (ZnO) nanoparticles (NPs) on the NFs surface. The morphological study verified that ZnO NPs are uniformly distributed on the surface of CAR/PAN NFs. Through EDX and XRD analysis, it was validated that the NPs are composed of ZnO and/or ZnO/Zn(OH)2. The presence of CAR and ZnO NPs brought about a superhydrophilicity effect and notably raised the elastic modulus and tensile strength of Zn-CAR/PAN NFs. While CAR ligands were shown to improve the viability of fibroblast (L929) and endothelial (HUVEC) cells, ZnO NPs lowered the positive impact of CAR, most likely due to their repulsive negative surface charge. A scratch assay verified that CAR/PAN NFs and Zn-CAR/PAN NFs aided HUVEC migration more than PAN NFs. Also, an antibacterial assay implied that CAR/PAN NFs and Zn-CAR/PAN NFs are significantly more effective in inhibiting Staphylococcus aureus (S. aureus) than neat PAN NFs are (1000 and 500%, respectively). Taken together, compared to the neat PAN NFs, CAR/PAN NFs with and without the biosynthesized ZnO NPs can support the cellular activities of relevance for wound healing and inactivate bacteria.

Mussel-inspired polydopamine decorated silane modified-electroconductive gelatin-PEDOT:PSS scaffolds for bone regeneration

This study seeks to simulate both the chemistry and piezoelectricity of bone by synthesizing electroconductive silane-modified gelatin-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) scaffolds using the freeze drying technique. In order to enhance hydrophilicity, cell interaction, and biomineralization, the scaffolds were functionalized with polydopamine (PDA) inspired by mussels. Physicochemical, electrical, and mechanical analyses were conducted on the scaffolds, as well as in vitro evaluations using the osteosarcoma cell line MG-63. It was found that scaffolds had interconnected porous structures, so the PDA layer formation reduced the size of pores while maintaining scaffold uniformity. PDA functionalization reduced the electrical resistance of the constructs while improving their hydrophilicity, compressive strength, and modulus. As a result of the PDA functionalization and the use of silane coupling agents, higher stability and durability were achieved as well as an improvement in biomineralization capability after being soaked in SBF solution for a month. Additionally, the PDA coating enabled the constructs to enhance viability, adhesion, and proliferation of MG-63 cells, as well as to express alkaline phosphatase and deposit HA, indicating that scaffolds can be used for bone regeneration. Therefore, the PDA-coated scaffolds developed in this study and the non-toxic performance of PEDOT:PSS present a promising approach for further in vitro and in vivo studies.

Management of contralateral molar teeth with necrotic pulp and open apexes using platelet-rich plasma and vital pulp therapy

Regenerative endodontics holds promising potential for the regeneration of living tissues in teeth with necrotic pulp and periapical lesion. Platelet-rich plasma can be easily prepared and used as an ideal scaffold for pulp regeneration.

Progress of Microfluidic Hydrogel-Based Scaffolds and Organ-on-Chips for the Cartilage Tissue Engineering

Cartilage degeneration is among the fundamental reasons behind disability and pain across the globe. Numerous approaches have been employed to treat cartilage diseases. Nevertheless, none have shown acceptable outcomes in the long run. In this regard, the convergence of tissue engineering and microfabrication principles can allow developing more advanced microfluidic technologies, thus offering attractive alternatives to current treatments and traditional constructs used in tissue engineering applications. Herein, the current developments involving microfluidic hydrogel-based scaffolds, promising structures for cartilage regeneration, ranging from hydrogels with microfluidic channels to hydrogels prepared by the microfluidic devices, that enable therapeutic delivery of cells, drugs, and growth factors, as well as cartilage-related organ-on-chips are reviewed. Thereafter, cartilage anatomy and types of damages, and present treatment options are briefly overviewed. Various hydrogels are introduced, and the advantages of microfluidic hydrogel-based scaffolds over traditional hydrogels are thoroughly discussed. Furthermore, available technologies for fabricating microfluidic hydrogel-based scaffolds and microfluidic chips are presented. The preclinical and clinical applications of microfluidic hydrogel-based scaffolds in cartilage regeneration and the development of cartilage-related microfluidic chips over time are further explained. The current developments, recent key challenges, and attractive prospects that should be considered so as to develop microfluidic systems in cartilage repair are highlighted.

A critical review on polydopamine surface-modified scaffolds in musculoskeletal regeneration

Increasing concern about age-related diseases, particularly musculoskeletal injuries and orthopedic conditions, highlights the need for strategies such as tissue engineering to address them. Surface modification has been developed to create pro-healing interfaces, personalize scaffolds and provide novel medicines. Polydopamine, a mussel-inspired adhesive polymer with highly reactive functional groups that adhere to nearly all substrates, has gained attention in surface modification strategies for biomaterials. Polydopamine was primarily developed to modify surfaces, but its effectiveness has opened up promising approaches for further applications in bioengineering as carriers and nanoparticles. This review focuses on the recent discoveries of the role of polydopamine as a surface coating material, with focus on the properties that make it suitable for tackling musculoskeletal disorders. We report the evolution of using it in research, and discuss papers involving the progress of this field. The current research on the role of polydopamine in bone, cartilage, muscle, nerve, and tendon regeneration is discussed, thus giving comprehensive overview about the function of polydopamine both in-vitro and in-vivo. Finally, the report concludes presenting the critical challenges that must be addressed for the clinical translation of this biomaterial while exploring future perspectives and research opportunities in this area.

Injectable light-assisted thermo-responsive methylcellulose-sodium humate hydrogel proposed for photothermal ablation and localized delivery of cisplatin

This study aimed to develop injectable light-assisted thermo-responsive methylcellulose hydrogels filled with sodium humate, which were proposed for photothermal ablation and localized cisplatin delivery. Sodium humate converts light energy from laser beams into thermal energy, which causes methylcellulose to gel, thereby controlling the release of chemotherapy agents. Meanwhile, light emission causes to the photothermal ablation of tumor cells. For determining the optimal production conditions, different concentrations of sodium humate and light emission times were investigated. Results show that hydrogel uniformity is highly dependent on variables. An increase in sodium humate concentration and emission time resulted in a slight reduction in swelling ratio and an increase in durability. According to the simulation conditions, the cisplatin release profile was consistent with a non-Fickian mechanism with a predominant erosion contribution. In conjugation with increasing light emission time and sodium humate content, the storage modulus and viscosity increased, demonstrating hydrogel’s sol-gel transition and long-lasting durability. The intrinsic fluorescence spectroscopy study revealed that the hydrogel-model protein complex empowered hydrogel bio-performance. Laser emission and cisplatin release synergistically reduced the number of viable osteosarcoma cell lines, suggesting the possibility of tumor ablation. This study describes the potential of simultaneous photothermal therapy and chemotherapy in osteosarcoma treatment, laying the groundwork for future preclinical and clinical trials.

Mussel-inspired polydopamine decorated alginate dialdehyde-gelatin 3D printed scaffolds for bone tissue engineering application

This study utilized extrusion-based 3D printing technology to fabricate calcium-cross-linked alginate dialdehyde-gelatin scaffolds for bone regeneration. The surface of polymeric constructs was modified with mussel-derived polydopamine (PDA) in order to induce biomineralization, increase hydrophilicity, and enhance cell interactions. Microscopic observations revealed that the PDA layer homogeneously coated the surface and did not appear to induce any distinct change in the microstructure of the scaffolds. The PDA-functionalized scaffolds were more mechanically stable (compression strength of 0.69 ± 0.02 MPa) and hydrophilic (contact angle of 26) than non-modified scaffolds. PDA-decorated ADA-GEL scaffolds demonstrated greater durability. As result of the 18-days immersion in simulated body fluid solution, the PDA-coated scaffolds showed satisfactory biomineralization. Based on theoretical energy analysis, it was shown that the scaffolds coated with PDA interact spontaneously with osteocalcin and osteomodulin (binding energy values of −35.95 kJ mol⁻¹ and −46.39 kJ mol⁻¹, respectively), resulting in the formation of a protein layer on the surface, suggesting applications in bone repair. PDA-coated ADA-GEL scaffolds are capable of supporting osteosarcoma MG-63 cell adhesion, viability (140.18% after 7 days), and proliferation. In addition to increased alkaline phosphatase secretion, osteoimage intensity also increased, indicating that the scaffolds could potentially induce bone regeneration. As a consequence, the present results confirm that 3D printed PDA-coated scaffolds constitute an intriguing novel approach for bone tissue engineering.

Three-dimensional bio-printing of decellularized extracellular matrix-based bio-inks for cartilage regeneration: a systematic review

Cartilage injuries are common problems that increase with the population aging. Cartilage is an avascular tissue with a relatively low level of cellular mitotic activity, which makes it impossible to heal spontaneously. To compensate for this problem, three-dimensional bio-printing has attracted a great deal of attention in cartilage tissue engineering. This emerging technology aims to create three-dimensional functional scaffolds by accurately depositing layer-by-layer bio-inks composed of biomaterial and cells. As a novel bio-ink, a decellularized extracellular matrix can serve as an appropriate substrate that contains all the necessary biological cues for cellular interactions. Here, this review is intended to provide an overview of decellularized extracellular matrix-based bio-inks and their properties, sources, and preparation process. Following this, decellularized extracellular matrix-based bio-inks for cartilage tissue engineering are discussed, emphasizing cell behavior and in-vivo applications. Afterward, the current challenges and future outlook will be discussed to determine the conclusing remarks.

Determinants of gold nanoparticle interactions with Proteins: Off-Target effect study

Photothermal therapy is one of the promising approaches toward cancer treatment. To date, several compounds have been developed for this application, among which nanoparticles are attracting ever-increasing attention. One of the obstacles in developing efficient photothermal nanoparticle agents is their off-target effect which is mainly mediated via non-specific interactions with proteins. Such interaction not only reduces the bioavailability of the agent but also will cause protein aggregation that can be lethal. So, gaining knowledge on the mechanisms mediating such interactions will facilitate development of more effective agents. Our last studies showed the mechanism of action of two modified gold nanoparticles, folic acid functionalized gold nanoparticles (FA-AuNPs) and gold shelled Fe₃O₄ nanoparticles (AuFeNPs), as photothermal agents. In the current work, we focus on the interaction of these two NPs with human serum albumin (HSA) and human hemoglobin (Hb) as model proteins. The complex formation between NPs and proteins was investigated by fluorescence spectroscopy, dynamic light scattering and circular dichroism. Our data distinguishes the very distinct mode of interaction of charged and neutral NPs with proteins. While the interaction of neutral AuFeNP to proteins is protein dependent, charged nanoparticles FA-AuNP interact indistinguishably with all proteins via electrostatic interactions. Moreover, complexes obtained from FA-AuNPs with proteins are more stable than that of AuFeNP. However, the secondary structure content of proteins in the presence of NPs indicates the insignificant effect of NPs on the secondary structure of these proteins. Our data propose that the charge functionalization of the NPs is an effective way for modulating the interaction of nanoparticles with proteins.

Protein-Based Hydrogels: Promising Materials for Tissue Engineering

The successful design of a hydrogel for tissue engineering requires a profound understanding of its constituents' structural and molecular properties, as well as the proper selection of components. If the engineered processes are in line with the procedures that natural materials undergo to achieve the best network structure necessary for the formation of the hydrogel with desired properties, the failure rate of tissue engineering projects will be significantly reduced. In this review, we examine the behavior of proteins as an essential and effective component of hydrogels, and describe the factors that can enhance the protein-based hydrogels' structure. Furthermore, we outline the fabrication route of protein-based hydrogels from protein microstructure and the selection of appropriate materials according to recent research to growth factors, crucial members of the protein family, and their delivery approaches. Finally, the unmet needs and current challenges in developing the ideal biomaterials for protein-based hydrogels are discussed, and emerging strategies in this area are highlighted.

A Facile Method to Synthesize 3D Pomegranate-like Polydopamine Microspheres

Nanospheres have found versatile applications in the biomedical field; however, their possible harmful effects on immune and inflammatory systems are also a crucial concern. Inspired by a pomegranate structure, we demonstrated a novel structure for the nanostructured microspheres to overcome the drawbacks of nanospheres without compromising their merits. In this study, 3D pomegranate-like polydopamine microspheres (PDAMS) were synthesized by self-oxidative polymerization of dopamine hydrochloride. Herein, controlling the pH during polymerization led to synthesizing homogeneous agglomerated nano-sized spheres (400–2000 nm) and finally forming tunable and monodisperse micron-sized particles (21 µm) with uniform spherical shape porous microstructure. PDAMS interaction with the potential targets, Bone morphogenetic protein-2 (BMP2), Decorin, and Matrilin-1, was investigated via molecular calculations. Theoretical energy analysis revealed that PDAMS interaction with BMP2, Decorin, and Matrilin-1 is spontaneous, so that a protein layer formation on the PDAMS surface suggests application in bone and cartilage repair. It was also observed that PDAMS presented in-vitro degradation within 4 weeks. Here, disappearance of the UV-VIS spectrum peak at 280 nm is accompanied by the degradation of catechol groups. Pomegranate-like PDAMS support the biomimetic formation of hydroxyapatite-like layers, making them appropriate candidates for hard tissue applications. Herein, the appearance of peaks in XRD spectrum at 31.37, 39.57, 45.21, and 50.13° attributed to hydroxyapatite-like layers formation. All these results demonstrated that self-oxidative polymerization under a controllable pH can be a green and straightforward technique for preparing the pomegranate-like PDAMS and providing an innovative basis for further pre-clinical and clinical investigations.

The Dibenzyl Isoquinoline Alkaloid Berbamine Ameliorates Osteoporosis by Inhibiting Bone Resorption

Postmenopausal osteoporosis (PMOP) is a kind of primary osteoporosis that is characterized by decreased bone density and strength. Berbamine is a nonbasic quaternary benzylisoquinoline plant alkaloid that has been widely used in the clinic to treat leukopenia in China. We found that berbamine inhibited RANKL-induced osteoclastogenesis of bone marrow-derived macrophages (BMMs) in vitro, which mainly occurred in the middle phase and late phase. The gene and protein expression levels of osteoclast-related molecules, including CTSK, MMP-9, NFATc1, CD44 and DC-STAMP, were also downregulated by berbamine. In vivo, we treated PMOP mice with berbamine for 8 weeks and found that the extent of osteoporosis was alleviated significantly according to micro-CT scanning, hematoxylin-eosin staining, DC-STAMP immunohistochemical staining and TRAP immunohistochemical staining in the distal femurs of the mice. Our findings demonstrate that berbamine has an inhibitory effect on the osteoclastogenesis of BMMs and can prevent bone loss after ovariectomy in vivo. This study provides evidence that berbamine is a potential drug for the prevention and treatment of PMOP.

Bioactive Inks Development for Osteochondral Tissue Engineering: A Mini-Review

Nowadays, a prevalent joint disease affecting both cartilage and subchondral bone is osteoarthritis. Osteochondral tissue, a complex tissue unit, exhibited limited self-renewal potential. Furthermore, its gradient properties, including mechanical property, bio-compositions, and cellular behaviors, present a challenge in repairing and regenerating damaged osteochondral tissues. Here, tissue engineering and translational medicine development using bioprinting technology provided a promising strategy for osteochondral tissue repair. In this regard, personalized stratified scaffolds, which play an influential role in osteochondral regeneration, can provide potential treatment options in early-stage osteoarthritis to delay or avoid the use of joint replacements. Accordingly, bioactive scaffolds with possible integration with surrounding tissue and controlling inflammatory responses have promising future tissue engineering perspectives. This minireview focuses on introducing biologically active inks for bioprinting the hierarchical scaffolds, containing growth factors and bioactive materials for 3D printing of regenerative osteochondral substitutes.

Polydopamine nanospheres coated with bovine serum albumin permit enhanced cell differentiation: fundamental mechanism and practical application for protein coating formation

Protein coating is a strategy for modifying and improving the surface functional properties of nanomaterials. However, the underlying mechanism behind protein coating formation, which is essential for its practical applications, remains largely unknown. Herein, we investigate the fundamental molecular mechanism of protein coating formation. Polydopamine nanospheres (PDANS) coated with bovine serum albumin (BSA) are examined in this study due to their wide biomedical potential. Our results demonstrate that BSAs can flexibly bind to PDANS and maintain their structural dynamicity. Our findings unveil that regular structure formation arises from BSAs lateral interactions via electrostatic forces. Notably, the protein coating modified PDANS surface enhances cell adhesion and proliferation as well as osteogenic differentiation. Such an enhancement is attributed to complementary surface properties provided by the dynamic PDANS-BSA complex and regular structure caused by BSA-BSA interactions in protein coating formation. This study provides a fundamental understanding of the molecular mechanism of protein coating formation, which facilitates the further development of functional protein-coated nanomaterials and guides the bioengineering decision making for biomedical applications, especially in bone tissue engineering.

Tuning the biomimetic behavior of hybrid scaffolds for bone tissue engineering through surface modifications and drug immobilization

Bone defects arising from injury and/or disease are a common and debilitating clinical lesion. While the development of tissue microenvironments utilizing biomimetic constructs is an emerging approach for bone tissue engineering. In this context, bioactive glass nanoparticles (BGNPs) were embedded within polycaprolactone (PCL) scaffolds. The scaffolds exhibit an engineered unidirectional pore structure which are surface activated via oxygen plasma to allow immobilization of simvastatin (SIM) on the pore surface. Microscopic observation indicated the surface modification did not disturb the lamellar orientation of the pores improving the biomimetic formation of hydroxyapatite. Mathematically modelled release profiles reveal that the oxygen plasma pre-treatment can be utilized to modulate the release profile of SIM from the scaffolds. With the release mechanism controlled by the balance between the diffusion and erosion mechanisms. Computational modelling shows that Human Serum Albumin and Human α₂-macroglobulin can be utilized to increase SIM bioavailability for cells via a molecular docking mechanism. Cellular studies show positive MG-63 cell attachment and viability on optimized scaffolds with alkaline phosphatase activity enhanced along with enhanced expression of osteocalcoin biomarker.

Schisandrin A restrains osteoclastogenesis by inhibiting reactive oxygen species and activating Nrf2 signalling

Objectives

Intracellular reactive oxygen species (ROS) induced by receptor activator of NF‐kB ligand (RANKL) has been proven to be a critical factor in the development of osteoclasts. This study aimed to prove that schisandrin A (Sch), a novel anti‐oxidant compound, is able to suppress osteoclastogenesis and prevent bone loss in ovariectomized (OVX) mice by suppressing ROS via nuclear factor erythroid 2‐related factor (Nrf2).

Material and Methods

Micro‐CT was used to detect bone formation. The effects of Sch on receptor activator of nuclear factor‐κB (NF‐κB) ligand (RANKL)‐induced reactive oxygen species (ROS) were measured by dihydroethidium (DHE) staining in vivo and 2',7'‐dichlorodihydrofluorescein diacetate (DCFH‐DA) staining in vitro. Immunofluorescence staining was used to detect the expression of Nrf2 in vivo. siRNA was used to evaluate the effect of Nrf2 in osteoclastogenesis.

Results

Sch suppresses RANKL‐induced ROS production by regulating nuclear factor erythroid 2‐related factor (Nrf2) in vitro and vivo. Mechanistically, Sch enhances the expression of Nrf2 by regulating the degradation of Nrf2. Further, Sch suppresses phosphorylation of P65 and its nuclear translocation, as well as the degradation of IκBα. Collectively, our findings reveal that Sch protects against OVX‐induced bone loss by suppressing ROS via Nrf2.

Conclusions

Our results showed the potential of anti‐oxidant compound schisandrin A in the treatment of osteoporosis, highlighting Nrf2 as a novel promising target in osteoclast‐related disease.

Effects of lamellar microstructure of retinoic acid loaded-matrixes on physicochemical properties, migration, and neural differentiation of P19 embryonic carcinoma cells

In this study, retinoic acid loaded-PLGA-gelatin matrixes were prepared with both freeze-casting and freeze-drying techniques. Herein, the effect of unidirectional microstructure with tunable pores on release profile, cellular adhesion, migration, and differentiation was compared. Morphological observation determined that highly interconnected porous structure can be formed, but lamellar pore channels were observed in freeze-casting prepared constructs. The absorption ratio was increased, and the biodegradation rate was decreased as a function of the orientation of microstructure. The in-vitro release study illustrated non-Fickian release mechanism in both methods, so that erosion has predominated over diffusion. Accordingly, PLGA-gelatin scaffolds prepared with freeze-drying technique showed no adequate erosion due to the rigid structure, while freeze-casting one presented more favorable erosion. Microscopic observations of adhered P19 embryonic cells on the scaffolds showed that the freeze-casting matrixes with unidirectional pores provide a more compatible microenvironment for cell attachments and spreading. Besides, it facilitated cell migration and penetration inside the structure and may act as guidance for neuron growth. Improvement in the expression of neural genes in unidirectionally oriented pores proved the decisive role of contact guidance for nerve healing. It seems that the freeze-cast PLGA-gelatin-retinoic acid scaffolds have initial features for nerve tissue regeneration studies.

Mussel-inspired polydopamine-mediated surface modification of freeze-cast poly (ε-caprolactone) scaffolds for bone tissue engineering applications

There are many methods used to fabricate the scaffolds for tissue regeneration, among which freeze casting has attracted a great deal of attention due to the capability to create a unidirectional structure. In this study, polycaprolactone (PCL) scaffolds were fabricated by freeze-casting technology in order to create porous microstructure with oriented open-pore channels. To induce biomineralization, and to improve hydrophilicity and cell interactions, mussel-inspired polydopamine (PDA) was coated on the surface of the freeze-cast PCL constructs. Then, the synergistic effects of oriented microstructure and deposited layer on efficient reconstruction of injured bone were studied. Microscopic observations demonstrated that, the coated layer did not show any special change in lamellar microstructure of the scaffolds. Water-scaffold interactions were evaluated by contact angle measurements, and they demonstrated strong enhancement in the hydrophilicity of the polymeric scaffolds after PDA coating. Biodegradation ratio and water uptake evaluation confirmed an increase in the measured values after PDA precipitation. The biomineralization of the PDA-coated scaffolds was characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD). Obtained results confirmed biomineralization of the constructs after a 28-day immersion in a simulated body fluid (SBF) solution. Mechanical analysis demonstrated higher compressive strength after PDA coating. L929 fibroblast cell viability and attachment illustrated that PDA-coated PCL scaffolds are able to support cell adhesion and proliferation. The increased secretion of alkaline phosphatase (ALP) after culturing osteosarcoma cell lines (MG-63) revealed the initial capability of scaffolds to induce bone regeneration. Therefore, the PDA-coated scaffolds introduce a promising approach for bone tissue engineering application.

Mussel-inspired polydopamine induced the osteoinductivity to ice-templating PLGA-gelatin matrix for bone tissue engineering application

In this study, poly(lactic-co-glycolic acid) (PLGA)-gelatin scaffolds were fabricated using the freeze-casting technique. Polydopamine (PDA) coating was applied on the surface of scaffolds to enhance the hydrophilicity, bioactivity, and cellular behavior of the composite constructs. Further, the synergistic effect of PDA coating and lamellar microstructure of scaffolds was evaluated on the promotion of properties. Based on morphological observations, freeze-casting constructs showed lamellar pore channels while the uniformity and pore size were slightly affected by deposition of PDA. The hydrophilicity and swelling capacity of the scaffolds were assessed using contact angle measurement and phosphate buffered saline absorption ratio. The results indicated a significant increment in water-matrix interactions following surface modification. The evaluation of the biodegradation ratio revealed the higher degree of degradation in PDA-coated samples owing to the presence of hydrophilic functional groups in the chemical structure of PDA. On the other hand, the bioactivity potential of PDA in the simulated body fluid solution confirmed the possibility of using coated constructs as a bone reconstructive substitute. The improvement of cellular attachment and filopodia formation in PDA-contained matrixes was the other benefit of the coating process. Furthermore, cellular proliferation and ALP activity were enhanced after PDA coating. The suggested PDA-coated PLGA-gelatin scaffolds can be applied in bone tissue regeneration.

An efficient functionalization of dexamethasone-loaded polymeric scaffold with [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane coupling agent for bone regeneration: Synthesis, characterization, and in vitro evaluation

In this study, dexamethasone-loaded gelatin–starch scaffolds were fabricated by the freeze-drying technique under different cooling temperatures and polymeric compositions. The constructs were modified via [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane coupling agent in order to produce a bioactive network structure for bone tissue engineering applications. Herein, the synergistic effect of [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane and dexamethasone was examined on the bioactivity and osteogenic behavior of scaffolds. Based on scanning electron microscopy micrographs, more fine pores were formed at higher freezing temperatures. The prepared microstructure at a rapid freezing rate resulted in diminished mechanical properties and a greater level of swelling and durability compared with a slow freezing rate. According to the acquired results, the mechanical strength decreased, while both absorption capacity and mass loss rate increased as a function of starch addition. Furthermore, the enhancement of hydrophilicity and reduction of mechanical stability enhanced the dexamethasone release levels. In addition, the synthesized constructs confirmed the positive effect of [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane and dexamethasone on biomimetic mineralization of the scaffolds. Supporting the cellular adhesion and proliferation alongside the expression of alkaline phosphatase, especially in the presence of dexamethasone, was the other advantage of synthetic scaffolds as a bone reconstructive substitute. Accordingly, drug-loaded hybrid constructs seem to be promising for further preclinical and clinical investigations in bone tissue engineering.

Fabrication and characterisation of super-paramagnetic responsive PLGA-gelatine-magnetite scaffolds with the unidirectional porous structure: a physicochemical, mechanical, and in vitro evaluation

Architecture and composition of Scaffolds are influential factors in the regeneration of defects. Herein, synthesised iron oxide (magnetite) nanoparticles (MNPs) by co-precipitation technique were evenly distributed in polylactic-co-glycolic acid (PLGA)-gelatine Scaffolds. Hybrid structures were fabricated by freeze-casting method to the creation of a matrix with tunable pores. The synthesised MNPs were characterised by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and vibrating sample magnetometer analysis. Scanning electron microscopy micrographs of porous Scaffolds confirmed the formation of unidirectional microstructure, so that pore size measurement indicated the orientation of pores in the direction of solvent solidification. The addition of MNPs to the PLGA-gelatine Scaffolds had no particular effect on the morphology of the pores, but reduced slightly pore size distribution. The MNPs contained constructs demonstrated increased mechanical strength, but a reduced absorption capacity and biodegradation ratio. Stability of the MNPs and lack of iron release was the point of strength in this investigation and were determined by atomic absorption spectroscopy. The evolution of rat bone marrow mesenchymal stem cells performance on the hybrid structure under a static magnetic field indicated the potential of super-paramagnetic constructs for further pre-clinical and clinical studies in the field of neural regeneration.

Physicochemical and biological investigation of oxygen plasma modified electrospun polyurethane scaffolds for connective tissue engineering application

In this study, electrospinning was selected to fabricate randomly oriented polyurethane (PU) nanofibers for tissue engineering application, and the surface of scaffolds was exposed to oxygen plasma flow. The morphology structure of the PU scaffolds before and after oxygen plasma treatment was observed using scanning electron microscopy (SEM) micrographs, and the fiber diameter distribution was measured using Image J software. The results demonstrated that oxygen plasma modification reduces the fiber diameter without any other special effects on fiber microstructure. Water drop contact angle and swelling ratio of PU constructs were performed to estimate the water-scaffolds interactions. The results revealed improvement of hydrophilicity by oxygen plasma treatment. Atomic force microscopy test was done to analyze a topological characteristic of the scaffolds, and it was found out that oxygen plasma treatment decreases the roughness of the scaffolds. The biological behavior of the scaffolds was investigated by SEM observation and MTT assay after L-929 fibroblast cells culture. In vitro assays demonstrated biocompatibility, cellular attachments, and filopodia formation on plasma modified samples. These results suggest that oxygen plasma treatment improves the physicochemical and biological properties of PU scaffolds to create a more hydrophilic surface which facilitates cell attachments and proliferation.

A facile method to synthesize mussel-inspired polydopamine nanospheres as an active template for in situ formation of biomimetic hydroxyapatite

In this study, Mussel-inspired polydopamine (PDA) nanospheres were synthesized via spontaneous oxidative polymerization of dopamine hydrochloride (dopa-HCl) in a deionized water-alcohol mixed solvent at room temperature and atmospheric air, under alkaline condition. Field-emission scanning electron microscopy (FE-SEM) demonstrated production of sphere-like shape with a smooth surface and tunable size, while monodispersity increased by utilizing isopropanol instead of ethanol owing to lower R_a values based on Hansen solubility parameter (HSP) theory. Dropwise addition of monomer played an undeniable role in the fabrication of uniform and smaller spheres. The difference of the charge repulsion of constructs in the range of pH led to different dispersive behavior in a variety of solvents, exhibiting versatile applications. The presence of active functional groups on the surface of PDA spheres made them an appropriate option for PDA-assisted biomimetic mineralization of hydroxyapatite (HA), which is the result of the interaction between abundant catecholamine moieties in PDA and Ca⁺² ions in simulated body fluid. Bio-adhesive nature of PDA in water and the presence of amino and hydroxyl functional groups support desirable L929 mouse fibroblast cell spreading. The viability of >90% fibroblast cells proved the biocompatibility of polymerized structure. All the achievements indicated that PDA nanospheres provide a biocompatible and bioactive template for green synthesizing hydroxyapatite and the innovative basis for further tissue engineering applications.

Oxygen-plasma treatment-induced surface engineering of biomimetic polyurethane nanofibrous scaffolds for gelatin-heparin immobilization

Polyurethane (PU) has been extensively used in vascular tissue engineering due to its outstanding mechanical performance and blood compatibility behavior. Here, biomimetic PU-based scaffolds were prepared using an electrospinning technique and gelatin-heparin was introduced as a surface modifier after oxygen plasma treatment to improve cell attachment and release an anticoagulation agent. Morphology, Fourier transform infrared (FTIR) spectroscopy, compression strength, swelling and biodegradation ratio, drug release level and cellular interactions were evaluated. According to the scanning electron microscopy (SEM) micrographs, gelatin-heparin immobilized PU nanofibers exhibited a smooth surface and a bead free structure that nanofibers distributed in the range of 300–1000 nm. The mechanical strength of constructs, swelling and biodegradation ratio, and drug release level illustrated higher values for oxygen plasma-treated samples compared with bilayered scaffolds. Cellular adhesion and biocompatibility ameliorated after plasma treatment. All the mentioned findings indicated the initial physicomechanical and biological potential of biomimetic PU-based fibers in the improvements of vascular scaffolds.

Microwave-induced rapid formation of biomimetic hydroxyapatite coating on gelatin-siloxane hybrid microspheres in 10X-SBF solution

Bioactive materials can attract calcium and phosphate ions in simulated body fluid (SBF) solution to mimic the composition of extracellular matrix (ECM). Rapid biodegradation rate of natural polymers in contact with water-based solutions and time-consuming process of mineralization in SBF led to using concentrated simulated media. Herein, gelatin-siloxane microspheres were fabricated via single emulsion method. Then hybrid spheres were immersed in the modified 10X-SBF solution, and microwave energy (600 W) was expanded for the rapid formation of hydroxyapatite (HA) on the spheres. Results indicated homogeneous coating of microspheres and high similarity of synthesized HA to the bone composition. Increasing intensity of HA-related peaks in Fourier transform infrared spectrum, X-ray diffraction and surface roughness after utilizing microwave-assisted method confirmed high efficiency of this technique in biomimetic mineralization of structures. Cell culture studies with human osteosarcoma cell lines (MG-63) demonstrated that mineralized HA in 10X-SBF solution under microwave treatment could be able to mimic bone ECM for tissue regeneration applications in the shortest time and highest similarity to the natural tissue.

Deceased Organ Donation From Pediatric Donors: Does the Literature Really Help Us? Implication for More Powerful Guidelines

BACKGROUND

Brain-dead pediatric donors have always been the focus of attention because of the higher quality, utility, and possibility of their organ donation. However, donors under the age of 5 years always necessitate making more challenging management efforts, which are not clearly implied in most parts of the guidelines.

METHODS

The data obtained from 79 brain-dead pediatric donors of the Organ Procurement Unit of Masih Daneshvari Hospital, Tehran, Iran, were assessed. The donors were divided into 2 groups, including donors under 5 years of age (group A) and those between 5 and 12 years of age (group B). Metabolic, hemodynamic, hematologic, and electrolyte status as well as the suitability for donation were compared in the study groups.

RESULTS

Of 1252 donors, 6.3% were under 12 years of age. Trauma and drug toxicity were the two primary causes of brain death in group A. In comparison, trauma and brain tumor were the leading causes of brain death in group B. The prevalence of both hyperglycemia and respiratory acidosis was significantly higher in group A (P < .05). However, severe anemia and coagulopathy were more prevalent in group B (P < .05). The high-dose inotropic administration was used for 42.4% of the donors in group A, whereas only 26% of the donors in group B needed a high dose of inotropes (P < .05). The mean quantity of organ harvested per donor was 2.1 and 2.25 in groups A and B, respectively. Furthermore, donor loss was not significantly different in both groups.

CONCLUSIONS

The occurrence of different complications in donors under the age of 5 years requires special treatment considerations that should be the center of attention in the related guidelines. Organ donation per donor indicates that donors under the age of 5 years are a valuable resource for organ procurement.

Bi-layered electrospun nanofibrous polyurethane-gelatin scaffold with targeted heparin release profiles for tissue engineering applications

Tissue engineering is a biotechnology that is used to develop biological substitutes to restore, maintain, or improve functions. Thus, the porous scaffolds are used to accommodate cells in tissue engineering. In this research, three dimensional (3D) bi-layered polyurethane (PU)-gelatin nanofibrous scaffolds were prepared by the electrospinning method, after which the capability of the released heparin as an anti-coagulation factor was evaluated. Electrospinning has been extensively investigated for the preparation of fibers that exhibit a high surface area to volume ratio. Results showed that scanning electron microscopy (SEM) micrographs exhibited a smooth surface as well as a highly porous and bead-free structure, in which fibers were distributed in the range of 100–600 nm. The modulus and ultimate tensile strength (UTS) decreased and increased, respectively, after crosslinking the reaction of polymers. This process also reduced swelling ratio, the hydrolytic biodegradation rate, and the release rate as a function of time. Moreover, an in vitro assay demonstrated that 3D nanofibrous scaffolds supported L929 fibroblast cell viability and that cells adhered and spread on the fibers. Based on the obtained results, the heparin-loaded electrospinning nanofibrous scaffolds have initial physicochemical and mechanical properties to protect neo-tissue formation.

Efficacy of recruitment maneuver for improving the brain dead marginal lungs to ideal

BACKGROUND

Because of the shortage of lungs for transplantation, finding the suitable lungs in brain-dead donors is an important issue. Recruitment maneuver is a strategy aimed at re-expanding collapsed and edematous lung tissue. The aim of this study was to assess the efficacy of this maneuver on improving marginal lungs for transplantation.

METHODS

From 127 brain-dead potential donor which were evaluated for lung donation in Masih Daneshvari Organ Procurement Unit of Tehran, Iran, 31 (25%) had marginal lungs for transplantation. These donors had normal chest X ray or bilateral infiltration and had PaO2 200-300 mm Hg with FIO2 100%. The recruitment maneuver was performed and arterial blood gas was obtained before and after maneuver. The maneuver lasts for 2 hours with continuous check of O2 saturation and patient's hemodynamic during. Finally, patients with normal bronchoscopy and PaO2/FIO2 >300 mm Hg were considered good candidates for lung transplantation. The frequency (%) and mean ± SD were used for description of variables and the Wilcoxon test was used for comparison between pre- and post-maneuver PaO2 with FIO2 100%.

RESULTS

The mean ± SD of PaO2/FIO2 with 100% FIO2 of patients before and after recruitment were 239 ± 62 and 269 ± 91, respectively. Recruitment maneuver could convert 10 marginal lungs (32%) to appropriate ones (PaO2 > 300) and finally 8 lungs were transplanted.

CONCLUSIONS

Findings of this study showed that recruitment maneuver could convert inappropriate lungs to appropriate ones in one third of brain-dead patients who had marginal lung condition. So, it is recommended that this maneuver is considered in the assessment protocol of lungs for donation.

Effects of sulfur water extraction on anthocyanins properties of tepals in flower of saffron (Crocus sativus L)

A sulfur solution with different metabisulfite concentrations (100, 400, 700, 1,000 and 2,000 ppm) was used to extract anthocyanins from saffron tepals. The extraction process was compared with acidified ethanol solution at similar extraction times of 20, 40, 60, 120, and 180 min at 40 °C. The recovery of anthocyanins with sulfur solution was higher than ethanol extraction and reached to 700 mg anthocyanins/100 g, when the sulfur concentration and extraction time were 700 ppm and 60 min, respectively. HPLC analysis showed that anthocyanins extracted with sulfur solution followed by partial desulfurization and reducing sulfur content (to less than 250 ppm) had around 100 % more cyanidin 3 glucosides and 100 % less pelargonidin 3,5 glucosides in comparison with ethanol extraction. Additionally, the color of low-sulfured anthocyanins had more saturation (chroma), less lightness, and more stability than the one extracted with ethanol solution. While monomeric and polymeric anthocyanins extracted with sulfur solution had less than 1 % changes after 3 h extraction time, they had more than 12 % changes when they extracted with alcoholic solution at similar conditions. Overall, the sulfur method had a potential to extract stable anthocyanins from waste and discarded saffron tepals in aqueous solvent, and with higher quantity and quality (more attractive color) than conventional ethanol extraction method.