Biomaterials and tissue engineering in traumatic brain injury: novel perspectives on promoting neural regeneration

Traumatic brain injury is a serious medical condition that can be attributed to falls, motor vehicle accidents, sports injuries and acts of violence, causing a series of neural injuries and neuropsychiatric symptoms. However, limited accessibility to the injury sites, complicated histological and anatomical structure, intricate cellular and extracellular milieu, lack of regenerative capacity in the native cells, vast variety of damage routes, and the insufficient time available for treatment have restricted the widespread application of several therapeutic methods in cases of central nervous system injury. Tissue engineering and regenerative medicine have emerged as innovative approaches in the field of nerve regeneration. By combining biomaterials, stem cells, and growth factors, these approaches have provided a platform for developing effective treatments for neural injuries, which can offer the potential to restore neural function, improve patient outcomes, and reduce the need for drugs and invasive surgical procedures. Biomaterials have shown advantages in promoting neural development, inhibiting glial scar formation, and providing a suitable biomimetic neural microenvironment, which makes their application promising in the field of neural regeneration. For instance, bioactive scaffolds loaded with stem cells can provide a biocompatible and biodegradable milieu. Furthermore, stem cells-derived exosomes combine the advantages of stem cells, avoid the risk of immune rejection, cooperate with biomaterials to enhance their biological functions, and exert stable functions, thereby inducing angiogenesis and neural regeneration in patients with traumatic brain injury and promoting the recovery of brain function. Unfortunately, biomaterials have shown positive effects in the laboratory, but when similar materials are used in clinical studies of human central nervous system regeneration, their efficacy is unsatisfactory. Here, we review the characteristics and properties of various bioactive materials, followed by the introduction of applications based on biochemistry and cell molecules, and discuss the emerging role of biomaterials in promoting neural regeneration. Further, we summarize the adaptive biomaterials infused with exosomes produced from stem cells and stem cells themselves for the treatment of traumatic brain injury. Finally, we present the main limitations of biomaterials for the treatment of traumatic brain injury and offer insights into their future potential.

Biodegradable electrospun poly(L-lactide-co-ε-caprolactone)/polyethylene glycol/bioactive glass composite scaffold for bone tissue engineering

The field of tissue engineering has witnessed significant advancements in recent years, driven by the pursuit of innovative solutions to address the challenges of bone regeneration. In this study, we developed an electrospun composite scaffold for bone tissue engineering. The composite scaffold is made of a blend of poly(L-lactide-co-ε-caprolactone) (PLCL) and polyethylene glycol (PEG), with the incorporation of calcined and lyophilized silicate-chlorinated bioactive glass (BG) particles. Our investigation involved a comprehensive characterization of the scaffold's physical, chemical, and mechanical properties, alongside an evaluation of its biological efficacy employing alveolar bone-derived mesenchymal stem cells. The incorporation of PEG and BG resulted in elevated swelling ratios, consequently enhancing hydrophilicity. Thermal gravimetric analysis confirmed the efficient incorporation of BG, with the scaffolds demonstrating thermal stability up to 250°C. Mechanical testing revealed enhanced tensile strength and Young's modulus in the presence of BG; however, the elongation at break decreased. Cell viability assays demonstrated improved cytocompatibility, especially in the PLCL/PEG+BG group. Alizarin red staining indicated enhanced osteoinductive potential, and fluorescence analysis confirmed increased cell adhesion in the PLCL/PEG+BG group. Our findings suggest that the PLCL/PEG/BG composite scaffold holds promise as an advanced biomaterial for bone tissue engineering.

Fluocinolone Acetonide Loaded Chitosan Nanofiber Scaffolds for Treatment of Ocular Disorders: In Vitro Characterization, Ex-Vivo Corneal and Ex-Vivo Scleral Evaluation

PURPOSE

Drugs administered in the ocular region need to overcome ocular barriers without permanently damaging the ocular tissues. Moreover, ocular disorders of the posterior segment are more difficult to treat due to invasive procedures required to reach the posterior segment. Hence, to treat posterior disorders of the eye an attempt was made to develop nanofiber (NF) scaffolds for effective management of chronic posterior uveitis. Nanofibers (NFs) were formulated using the electrospinning technique.

METHODS

NF scaffolds were formulated using the electrospinning technique. The effect of different concentrations of chitosan on NF production was studied by considering different ratios of chitosan (CS) and polyvinyl alcohol (PVA). Physicochemical characterization of NFs was performed to evaluate developed NFs.

RESULTS

The optimized NF scaffold had a diameter of 129 ± 3 nm. NF scaffolds were found to have a tensile strength of 0.2882 ± 0.078 N/m2, thickness of 0.16 ± 0.05 mm, and drug entrapment of 95 ± 2.0%. The bioadhesive strength of the NF was found to be 257.3 ± 0.04 g/cm2 indicating high bioadhesion of NFs to the ocular tissues. The in-vitro, ex-vivo corneal and ex-vivo scleral drug release after 12 h was found to be 78.4 ± 1.0%, 65.33 ± 0.2% and 78.41 ± 1.0%, respectively. Ex-vivo whole eye model experiment indicated a concentration of about 40 ± 1.75% of drug permeated from corneal layer to the vitreous humor after 12 h. The Hen's egg test-chorioallantoic membrane study (HET-CAM) study and in-vitro cytotoxicity study on Statens Seruminstitut Rabbit Cornea (SIRC) cell lines indicated that the developed drug-loaded NF scaffolds were found to be non-toxic as compared to pure drug, thus suggesting cytocompatibility.

CONCLUSION

Results of HET-CAM, sterility and ex-vivo studies indicate that the developed formulation is non-toxic, sterile, and effective for the ocular delivery of fluocinolone acetonide to the posterior segment of eye.

Fabrication of Artificial Nerve Conduits Used in a Long Nerve Gap: Current Reviews and Future Studies

There are many commercially available artificial nerve conduits, used mostly to repair short gaps in sensory nerves. The stages of nerve regeneration in a nerve conduit are fibrin matrix formation between the nerve stumps joined to the conduit, capillary extension and Schwann cell migration from both nerve stumps, and, finally, axon extension from the proximal nerve stump. Artificial nerves connecting transected nerve stumps with a long interstump gap should be biodegradable, soft and pliable; have the ability to maintain an intrachamber fibrin matrix structure that allows capillary invasion of the tubular lumen, inhibition of scar tissue invasion and leakage of intratubular neurochemical factors from the chamber; and be able to accommodate cells that produce neurochemical factors that promote nerve regeneration. Here, we describe current progress in the development of artificial nerve conduits and the future studies needed to create nerve conduits, the nerve regeneration of which is compatible with that of an autologous nerve graft transplanted over a long nerve gap.

Decellularized Bovine Skeletal Muscle Scaffolds: Structural Characterization and Preliminary Cytocompatibility Evaluation

Skeletal muscle degeneration is responsible for major mobility complications, and this muscle type has little regenerative capacity. Several biomaterials have been proposed to induce muscle regeneration and function restoration. Decellularized scaffolds present biological properties that allow efficient cell culture, providing a suitable microenvironment for artificial construct development and being an alternative for in vitro muscle culture. For translational purposes, biomaterials derived from large animals are an interesting and unexplored source for muscle scaffold production. Therefore, this study aimed to produce and characterize bovine muscle scaffolds to be applied to muscle cell 3D cultures. Bovine muscle fragments were immersed in decellularizing solutions for 7 days. Decellularization efficiency, structure, composition, and three-dimensionality were evaluated. Bovine fetal myoblasts were cultured on the scaffolds for 10 days to attest cytocompatibility. Decellularization was confirmed by DAPI staining and DNA quantification. Histological and immunohistochemical analysis attested to the preservation of main ECM components. SEM analysis demonstrated that the 3D structure was maintained. In addition, after 10 days, fetal myoblasts were able to adhere and proliferate on the scaffolds, attesting to their cytocompatibility. These data, even preliminary, infer that generated bovine muscular scaffolds were well structured, with preserved composition and allowed cell culture. This study demonstrated that biomaterials derived from bovine muscle could be used in tissue engineering.

Patterned PCL/PGS Nanofibrous Hyaluronic Acid-Coated Scaffolds Promote Cellular Response and Modulate Gene Expression Profiles

Chronic wounds impose a significant burden on individuals and healthcare systems, necessitating the development of advanced wound management strategies. Tissue engineering, with its ability to create scaffolds that mimic native tissue structures and promote cellular responses, offers a promising approach. Electrospinning, a widely used technique, can fabricate nanofibrous scaffolds for tissue regeneration. In this study, we developed patterned nanofibrous scaffolds using a blend of poly(ε-caprolactone) (PCL) and poly(glycerol sebacate) (PGS), known for their biocompatibility and biodegradability. By employing a mesh collector, we achieved a unique fiber orientation pattern that emulated the natural tissue architecture. The average fiber diameter of PGS/PCL collected on aluminum foil and on mesh was found to be 665.2 ± 4 and 404.8 ± 16 nm, respectively. To enhance the scaffolds' bioactivity and surface properties, it was coated with hyaluronic acid (HA), a key component of the extracellular matrix known for its wound-healing properties. The HA coating improved the scaffold hydrophilicity and surface wettability, facilitating cell attachment, spreading, and migration. Furthermore, the HA-coated scaffold exhibited enhanced biocompatibility, promoting cell viability and proliferation. High-throughput RNA sequencing was performed to analyze the influence of the fabricated scaffold on the gene expression levels of endothelial cells. The top-upregulated biological processes and pathways include cell cycle regulation and cell proliferation. The results revealed significant alterations in gene expression profiles, indicating the scaffold's ability to modulate cellular functions and promote wound healing processes. The developed scaffold holds great promise for advanced wound management and tissue regeneration applications. By harnessing the advantages of aligned nanofibers, biocompatible polymers, and HA coating, this scaffold represents a potential solution for improving wound healing outcomes and improving the quality of life for individuals suffering from chronic wounds.

Polyethersulfone Polymer for Biomedical Applications and Biotechnology

Polymers stand out as promising materials extensively employed in biomedicine and biotechnology. Their versatile applications owe much to the field of tissue engineering, which seamlessly integrates materials engineering with medical science. In medicine, biomaterials serve as prototypes for organ development and as implants or scaffolds to facilitate body regeneration. With the growing demand for innovative solutions, synthetic and hybrid polymer materials, such as polyethersulfone, are gaining traction. This article offers a concise characterization of polyethersulfone followed by an exploration of its diverse applications in medical and biotechnological realms. It concludes by summarizing the significant roles of polyethersulfone in advancing both medicine and biotechnology, as outlined in the accompanying table.

Functionalization of PCL-Based Fiber Scaffolds with Different Sources of Calcium and Phosphate and Odontogenic Potential on Human Dental Pulp Cells

This study investigated the incorporation of sources of calcium, phosphate, or both into electrospun scaffolds and evaluated their bioactivity on human dental pulp cells (HDPCs). Additionally, scaffolds incorporated with calcium hydroxide (CH) were characterized for degradation, calcium release, and odontogenic differentiation by HDPCs. Polycaprolactone (PCL) was electrospun with or without 0.5% w/v of calcium hydroxide (PCL + CH), nano-hydroxyapatite (PCL + nHA), or β-glycerophosphate (PCL + βGP). SEM/EDS analysis confirmed fibrillar morphology and particle incorporation. HDPCs were cultured on the scaffolds to assess cell viability, adhesion, spreading, and mineralized matrix formation. PCL + CH was also evaluated for gene expression of odontogenic markers (RT-qPCR). Data were submitted to ANOVA and Student's t-test (α = 5%). Added CH increased fiber diameter and interfibrillar spacing, whereas βGP decreased both. PCL + CH and PCL + nHA improved HDPC viability, adhesion, and proliferation. Mineralization was increased eightfold with PCL + CH. Scaffolds containing CH gradually degraded over six months, with calcium release within the first 140 days. CH incorporation upregulated DSPP and DMP1 expression after 7 and 14 days. In conclusion, CH- and nHA-laden PCL fiber scaffolds were cytocompatible and promoted HDPC adhesion, proliferation, and mineralized matrix deposition. PCL + CH scaffolds exhibit a slow degradation profile, providing sustained calcium release and stimulating HDPCs to upregulate odontogenesis marker genes.

Melt Electrowriting Scaffolds with Fibre-guiding Features for Periodontal Attachment

Periodontal regeneration requires the re-attachment of oblique and perpendicular periodontal ligament (PDL) fibres to newly formed cementum and alveolar bone, which has proven elusive with existing approaches. In this study, multiple fibre-guiding biphasic tissue engineered constructs were fabricated by melt electrowriting. The biphasic scaffolds were 95% porous and consisted of a pore size gradient bone compartment and periodontal compartment made of fibre-guiding channels with micro-architectural features ranging from 100 to 60 µm aimed to direct PDL fibre alignment and attachment. In vitro evaluations over 3 and 7 days demonstrated a marked improvement in collagen fibre orientation (over 60% fully aligned) for scaffolds with micro-architecture ≤100 µm. The biphasic scaffolds were placed on a dentine slice and implanted ectopically, and this demonstrated that all micro-channels groups facilitated oblique and perpendicular alignment and attachment on the dentine with a mean nuclei angle and mean collagen fibre angle of approximately 60° resembling the native periodontal ligament attachment. A further in vivo testing using a surgically created rodent periodontal model highlighted the 80 µm micro-channel group's effectiveness, showing a significant increase in oblique PDL fibre attachment (72%) and periodontal regeneration (56%) when compared to all other groups onto the tooth root compared to control groups. Further to this, immunohistochemistry demonstrated the presence of periostin in the newly formed ligament indicating that functional regeneration occurred These findings suggest that scaffold micro-architectures of 100 microns or below can play a crucial role in directing periodontal tissue regeneration, potentially addressing a critical gap in periodontal therapy. STATEMENT OF SIGNIFICANCE: Periodontal regeneration remains a significant clinical challenge. Essential to restoring dental health and function is the proper attachment of the periodontal ligament, which is functionally oriented, to regenerated bone and cementum. Our research presents an innovative biphasic scaffold, utilizing Melt Electrowriting to systematically guide tissue growth. Distinct from existing methods, our scaffold is highly porous, adaptable, and precisely guides periodontal ligament fiber attachment to the opposing tooth root and alveolar bone interfaces, a critical step for achieving periodontal functional regeneration. Our findings not only bridge a significant gap in biomaterial driven tissue guidance but also promise more predictable outcomes for patients, marking a transformative advancement in the field.

Recent Advancements in Hydrogel Biomedical Research in Italy

Hydrogels have emerged as versatile biomaterials with remarkable applications in biomedicine and tissue engineering. Here, we present an overview of recent and ongoing research in Italy, focusing on extracellular matrix-derived, natural, and synthetic hydrogels specifically applied to biomedicine and tissue engineering. The analyzed studies highlight the versatile nature and wide range of applicability of hydrogel-based studies. Attention is also given to the integration of hydrogels within bioreactor systems, specialized devices used in biological studies to culture cells under controlled conditions, enhancing their potential for regenerative medicine, drug discovery, and drug delivery. Despite the abundance of literature on this subject, a comprehensive overview of Italian contributions to the field of hydrogels-based biomedical research is still missing and is thus our focus for this review. Consolidating a diverse range of studies, the Italian scientific community presents a complete landscape for hydrogel use, shaping the future directions of biomaterials research. This review aspires to serve as a guide and map for Italian researchers interested in the development and use of hydrogels in biomedicine.

Use of Plant Extracts in Polymeric Scaffolds in the Regeneration of Mandibular Injuries

Severe loss of bone mass may require grafting, and, among the alternatives available, there are natural biomaterials that can act as scaffolds for the cell growth necessary for tissue regeneration. Collagen and elastin polymers are a good alternative due to their biomimetic properties of bone tissue, and their characteristics can be improved with the addition of polysaccharides such as chitosan and bioactive compounds such as jatoba resin and pomegranate extract due to their antigenic actions. The aim of this experimental protocol was to evaluate bone neoformation in experimentally made defects in the mandible of rats using polymeric scaffolds with plant extracts added. Thirty rats were divided into group 1, with a mandibular defect filled with a clot from the lesion and no graft implant (G1-C, n = 10); group 2, filled with collagen/chitosan/jatoba resin scaffolds (G2-CCJ, n = 10); and group 3, with collagen/nanohydroxyapatite/elastin/pomegranate extract scaffolds (G3-CHER, n = 10). Six weeks after surgery, the animals were euthanized and samples from the surgical areas were submitted to macroscopic, radiological, histological, and morphometric analysis of the mandibular lesion repair process. The results showed no inflammatory infiltrates in the surgical area, indicating good acceptance of the scaffolds in the microenvironment of the host area. In the control group (G1), there was a predominance of reactive connective tissue, while in the grafted groups (G2 and G3), there was bone formation from the margins of the lesion, but it was still insufficient for total bone repair of the defect within the experimental period standardized in this study. The histomorphometric analysis showed that the mean percentage of bone volume formed in the surgical area of groups G1, G2, and G3 was 17.17 ± 2.68, 27.45 ± 1.65, and 34.07 ± 0.64 (mean ± standard deviation), respectively. It can be concluded that these scaffolds with plant extracts added can be a viable alternative for bone repair, as they are easily manipulated, have a low production cost, and stimulate the formation of new bone by osteoconduction.

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.

Characterization of Acellular Cartilage Matrix-Sodium Alginate Scaffolds in Various Proportions

The development of three-dimensional (3D) bioprinting technology has provided a new solution to address the shortage of donors, multiple surgeries, and aesthetic concerns in microtia reconstruction surgery. The production of bioinks is the most critical aspect of 3D bioprinting. Acellular cartilage matrix (ACM) and sodium alginate (SA) are commonly used 3D bioprinting materials, and there have been reports of their combined use. However, there is a lack of comprehensive evaluations on ACM-SA scaffolds with different proportions. In this study, bioinks were prepared by mixing different proportions of decellularized rabbit ear cartilage powder and SA and then printed using 3D bioprinting technology and crosslinked with calcium ions to fabricate scaffolds. The physical properties, biocompatibility, and toxicity of ACM-SA scaffolds with different proportions were compared. The adhesion and proliferation of rabbit adipose-derived stem cells on ACM-SA scaffolds of different proportions, as well as the secretion of Collagen Type II, were evaluated under an adipose-derived stem cell chondrogenic induction medium. The following conclusions were drawn: when the proportion of SA in the ACM-SA scaffolds was <30%, the printed structure failed to form. The ACM-SA scaffolds in proportions from 1:9 to 6:4 showed no significant cytotoxicity, among which the 5:5 proportion of ACM-SA scaffold was superior in terms of adhesiveness and promoting cell proliferation and differentiation. Although a higher proportion of SA can provide greater mechanical strength, it also significantly increases the swelling ratio and reduces cell proliferation capabilities. Overall, the 5:5 proportion of ACM-SA scaffold demonstrated a more desirable biological and physical performance.

Nanoparticle and Nanotopography-Induced Activation of the Wnt Pathway in Bone Regeneration

Background and Aims: Recent research has focused on developing nanoparticle and nanotopography-based technologies for bone regeneration. The Wingless-related integration site (Wnt) signaling pathway has been shown to play a vital role in this process, in particular in osteogenic differentiation and proliferation. The exact mechanisms by which nanoparticles and nanotopographies activate the Wnt signaling pathway, however, are not fully understood. This review aimed to elucidate the mechanisms by which nanoscale technologies activate the Wnt signaling pathway during bone regeneration. Methods: The terms "Wnt," "bone," and "nano*" were searched on PubMed and Ovid with no date limit. Only original research articles related to Wnt signaling and bone regeneration in the context of nanotopographies, nanoparticles, or scaffolds with nanotopographies/nanoparticles were reviewed. Results: The primary mechanism by which nanoparticles activated the Wnt pathway was by internalization through the endocytic pathway or diffusion through the cell membrane, leading to accumulation of nonphosphorylated β-catenin in the cytoplasm and subsequently downstream osteogenic signaling (e.g., upregulation of runt-related transcription factor 2 [RUNX2]). The specific size of the nanoparticles and the process of endocytosis itself has been shown to modulate the Wnt-β-catenin pathway. Nanotopographies were shown to directly activate frizzled receptors, initiating Wnt/β-catenin signaling. Additional studies showed nanotopographies to activate the Wnt/calcium (Wnt/Ca2+)-dependent and Wnt/planar cell polarity pathways through nuclear factor of activated T cells, and α5β1 integrin stimulation. Finally, scaffolds containing nanotopographies/nanoparticles were found to induce Wnt signaling through a combination of ion release (e.g., lithium, boron, lanthanum, and icariin), which inhibited glycogen synthase kinase 3 beta (GSK-3β) activity, and through similar mechanisms to the nanotopographies. Conclusion: This review concludes that nanoparticles and nanotopographies cause Wnt activation through several different mechanisms, specific to the size, shape, and structure of the nanoparticles or nanotopographies. Endocytosis-related mechanisms, integrin signaling and ion release were the major mechanisms identified across nanoparticles, nanotopographies, and scaffolds, respectively. Knowledge of these mechanisms will help develop more effective targeted nanoscale technologies for bone regeneration. Impact statement Nanoparticles and nanotopographies can activate the Wingless-related integration site (Wnt) signaling pathway, which is essential for bone regeneration. This review has identified that activation is due to endocytosis, integrin signaling and ion release, depending on the size, shape, and structure of the nanoparticles or nanotopographies. By identifying and further understanding these mechanisms, more effective nanoscale technologies that target the Wnt signaling pathway can be developed. These technologies can be used for the treatment of nonunion bone fractures, a major clinical challenge, with the potential to improve the quality of life of millions of patients around the world.

Bioengineering Skin Substitutes for Wound Management-Perspectives and Challenges

Non-healing wounds and skin losses constitute significant challenges for modern medicine and pharmacology. Conventional methods of wound treatment are effective in basic healthcare; however, they are insufficient in managing chronic wound and large skin defects, so novel, alternative methods of therapy are sought. Among the potentially innovative procedures, the use of skin substitutes may be a promising therapeutic method. Skin substitutes are a heterogeneous group of materials that are used to heal and close wounds and temporarily or permanently fulfill the functions of the skin. Classification can be based on the structure or type (biological and synthetic). Simple constructs (class I) have been widely researched over the years, and can be used in burns and ulcers. More complex substitutes (class II and III) are still studied, but these may be utilized in patients with deep skin defects. In addition, 3D bioprinting is a rapidly developing method used to create advanced skin constructs and their appendages. The aforementioned therapies represent an opportunity for treating patients with diabetic foot ulcers or deep skin burns. Despite these significant developments, further clinical trials are needed to allow the use skin substitutes in the personalized treatment of chronic wounds.

The H2O2 Self-Sufficient 3D Printed β-TCP Scaffolds with Synergistic Anti-Tumor Effect and Reinforced Osseointegration

Tumor recurrence and massive bone defects are two critical challenges for postoperative treatment of oral and maxillofacial tumor, posing serious threats to the health of patients. Herein, in order to eliminate residual tumor cells and promote osteogenesis simultaneously, the hydrogen peroxide (H2O2) self-sufficient TCP-PDA-CaO2-CeO2 (TPCC) scaffolds are designed by preparing CaO2 or/and CeO2 nanoparticles (NPs)/chitosan solution and modifying the NPs into polydopamine (PDA)-modified 3D printed TCP scaffolds by rotary coating method. CaO2 NPs loaded on the scaffolds can release Ca2+ and sufficient H2O2 in the acidic tumor microenvironment (TME). The generated H2O2 can further produce hydroxyl radicals (·OH) under catalysis effect by peroxidase (POD) activity of CeO2 NPs, in which the photothermal effect of the PDA coating enhances its POD catalytic effect. Overall, NPs loaded on the scaffold chemically achieve a cascade reaction of H2O2 self-sufficiency and ·OH production, while functionally achieving synergistic effects on anti-tumor and bone promotion. In vitro and in vivo studies show that the scaffolds exhibit effective osteo-inductivity, induced osteoblast differentiation and promote osseointegration. Therefore, the multifunctional composite scaffolds not only validate the concept of chemo-dynamic therapy (CDT) cascade therapy, but also provide a promising clinical strategy for postoperative treatment of oral and maxillofacial tumor.

Tissue Engineering Scaffolds Loaded With a Variety of Plant Extracts: Novel Model in Breast Cancer Therapy

Despite recent improvements in detecting and managing breast cancer (BC), it continues to be a major worldwide health concern that annually affects millions of people. Exploring the anti-BC potentials of natural compounds has received a lot of scientific attention due to their multi-target mode of action and good safety profiles because of these unmet needs. Drugs made from herbs are secure and have a lot fewer negative effects than those made from synthetic materials. Early stage patients benefit from breast-conserving surgery, but the risk of local recurrence remains, necessitating implanted scaffolds. These scaffolds provide residual cancer cell killing and tailored drug delivery. This review looks at plant extract-infused tissue engineering scaffolds, which provide a novel approach to treating BC. By offering patient individualized, safer treatments, these scaffolds could completely change how BC is treated.

Three dimensional (bio)printing of blood vessels: from vascularized tissues to functional arteries

Tissue engineering has emerged as a strategy for producing functional tissues and organs to treat diseases and injuries. Many chronic conditions directly or indirectly affect normal blood vessel functioning, necessary for material exchange and transport through the body and within tissue-engineered constructs. The interest in vascular tissue engineering is due to two reasons: (1) functional grafts can be used to replace diseased blood vessels, and (2) engineering effective vasculature within other engineered tissues enables connection with the host's circulatory system, supporting their survival. Among various practices, (bio)printing has emerged as a powerful tool to engineer biomimetic constructs. This has been made possible with precise control of cell deposition and matrix environment along with the advancements in biomaterials. (Bio)printing has been used for both engineering stand-alone vascular grafts as well as vasculature within engineered tissues for regenerative applications. In this review article, we discuss various conditions associated with blood vessels, the need for artificial blood vessels, the anatomy and physiology of different blood vessels, available 3D (bio)printing techniques to fabricate tissue-engineered vascular grafts and vasculature in scaffolds, and the comparison among the different techniques. We conclude our review with a brief discussion about future opportunities in the area of blood vessel tissue engineering.

Carboxymethylated and Sulfated Furcellaran from Furcellaria lumbricalis and Its Immobilization on PLA Scaffolds

This study involved the creation of highly porous PLA scaffolds through the porogen/leaching method, utilizing polyethylene glycol as a porogen with a 75% mass ratio. The outcome achieved a highly interconnected porous structure with a thickness of 25 μm. To activate the scaffold's surface and improve its hydrophilicity, radiofrequency (RF) air plasma treatment was employed. Subsequently, furcellaran subjected to sulfation or carboxymethylation was deposited onto the RF plasma treated surfaces with the intention of improving bioactivity. Surface roughness and water wettability experienced enhancement following the surface modification. The incorporation of sulfate/carboxymethyl group (DS = 0.8; 0.3, respectively) is confirmed by elemental analysis and FT-IR. Successful functionalization of PLA scaffolds was validated by SEM and XPS analysis, showing changes in topography and increases in characteristic elements (N, S, Na) for sulfated (SF) and carboxymethylated (CMF). Cytocompatibility was evaluated by using mouse embryonic fibroblast cells (NIH/3T3).

Specific tissue engineering for temporomandibular joint disc perforation

BACKGROUND

The temporomandibular joint (TMJ) disc is a critical fibrocartilaginous structure with limited regenerative capacity in the oral system. Perforation of the TMJ disc can lead to osteoarthritis and ankylosis of the TMJ because of the lack of disc protection. Clinical treatments for TMJ disc perforation, such as discectomy, hyaluronic acid injection, endoscopic surgery and high position arthroplasty of TMJ, are questionable with regard to long-term outcomes, and only three fourths of TMJ disc perforations are repairable by surgery, even in the short-term. Tissue engineering offers the potential for cure of repairable TMJ disc perforations and regeneration of unrepairable ones.

OBJECTIVES

This review discusses the classification of TMJ disc perforation and defines typical TMJ disc perforation. Advancements in the engineering-based repair of TMJ disc perforation by stem cell therapy, construction of a disc-like scaffold and functionalization by offering bioactive stimuli are also summarized in the review, and the barriers developing engineering technologies need to overcome to be popularized are discussed.

Optimization of Polycaprolactone and Type I Collagen Scaffold for Tendon Tissue Regeneration

Introduction Collagen synthesis is vital for restoring musculoskeletal tissues, particularly in tendon and ligamentous structures. Tissue engineering utilizes scaffolds for cell adhesion and differentiation. Although synthetic scaffolds offer initial strength, their long-term stability is surpassed by biological scaffolds. Combining polycaprolactone (PCL) toughness with collagen in scaffold design, this study refines fabrication via electrospinning, aiming to deliver enduring biomimetic matrices for widespread applications in musculoskeletal repair. Methods Electrospinning employed four solutions with varied collagen and PCL concentrations, dissolved in chloroform, methanol, and hexafluoro-2-propanol. Solutions were combined to yield 60 mg/mL concentrations with different collagen/PCL ratios. Electrospinning at 12-14kV voltage produced scaffolds, followed by vacuum-drying. Collagen coating was applied to PCL and 15% collagen/PCL scaffolds using a 0.1% collagen solution. SEM characterized fiber morphology, tensile testing was conducted to determine the mechanical properties of the scaffold, and Fourier-transform infrared (FTIR) spectroscopy analyzed scaffold composition. Atomic force microscopy (AFM) analyzed the stiffness properties of individual fibers, and a finite element model was developed to predict the mechanical properties. Cell culture involved seeding human bone marrow mesenchymal stem cells onto scaffolds, which were assessed through Alamar Blue assay and confocal imaging. Results Various scaffolds (100% PCL, PCL-15% collagen, PCL-25% collagen, PCL-35% collagen) were fabricated to emulate the extracellular matrix, revealing collagen's impact on fiber diameter reduction with increasing concentration. Tensile testing highlighted collagen's initial enhancement of mechanical strength, followed by a decline beyond PCL-15% collagen. FTIR spectroscopy detected potential hydrogen bonding between collagen and PCL. A finite element model predicted scaffold response to external forces which was validated by the tensile test data. Cell viability and proliferation assays demonstrated successful plating on all scaffolds, with optimal proliferation observed in PCL-25% collagen. Confocal imaging confirmed stem cell integration into the three-dimensional material. Collagen coating preserved nanofiber morphology, with no significant changes in diameter. Coating of collagen significantly altered the tensile strength of the scaffolds at the macro scale. AFM highlighted stiffness differences between PCL and collagen-coated PCL mats at the single fiber scale. The coating process did not significantly enhance initial cell attachment but promoted increased proliferation on collagen-coated PCL scaffolds. Conclusion The study reveals collagen-induced mechanical and morphological alterations, influencing fiber alignment, diameter, and chemical composition while emphasizing scaffolds' vital role in providing a controlled niche for stem cell proliferation and differentiation. The optimization of each of these scaffold characteristics and subsequent finite element modeling can lead to highly repeatable and ideal scaffold properties for stem cell integration and proliferation.

Recent Advances in Scaffolds for Guided Bone Regeneration

The rehabilitation of alveolar bone defects of moderate to severe size is often challenging. Currently, the therapeutic approaches used include, among others, the guided bone regeneration technique combined with various bone grafts. Although these techniques are widely applied, several limitations and complications have been reported such as morbidity, suboptimal graft/membrane resorption rate, low structural integrity, and dimensional stability. Thus, the development of biomimetic scaffolds with tailor-made characteristics that can modulate cell and tissue interaction may be a promising tool. This article presents a critical consideration in scaffold's design and development while also providing information on various fabrication methods of these nanosystems. Their utilization as delivery systems will also be mentioned.

Current approaches in tissue engineering-based nanotherapeutics for osteosarcoma treatment

Osteosarcoma (OS) is a malignant bone neoplasm plagued by poor prognosis. Major treatment strategies include chemotherapy, radiotherapy, and surgery. Chemotherapy to treat OS has severe adverse effects due to systemic toxicity to healthy cells. A possible way to overcome the limitation is to utilize nanotechnology. Nanotherapeutics is an emerging approach in treating OS using nanoparticulate drug delivery systems. Surgical resection of OS leaves a critical bone defect requiring medical intervention. Recently, tissue engineered scaffolds have been reported to provide physical support to bone defects and aid multimodal treatment of OS. These scaffolds loaded with nanoparticulate delivery systems could also actively repress tumor growth and aid new bone formation. The rapid developments in nanotherapeutics and bone tissue engineering have paved the way for improved treatment efficacy for OS-related bone defects. This review focuses on current bifunctional nanomaterials-based tissue engineered (NTE) scaffolds that use novel approaches such as magnetic hyperthermia, photodynamic therapy, photothermal therapy, bioceramic and polymeric nanotherapeutics against OS. With further optimization and screening, NTE scaffolds could meet clinical applications for treating OS patients.

Dimethyloxallyl glycine-loaded mesoporous bioactive glass/poly(D,L-lactide) composite scaffolds with ultrasound stimulation for promoting bone repair

Introduction: Bone tissue engineering is considered the ideal approach for bone repair. Mesoporous bioactive glass (MBG) possesses the characteristics of high drug-loading capacity and bioactivity. Low-intensity pulsed ultrasound contributes to promoting fracture healing and bone defect repair, and dimethyloxalyl glycine (DMOG) is a small molecular inhibitor that can suppress prolyl hydroxylase, reducing the degradation of hypoxia-inducible factor. Methods: In this study, we proposed to prepare DMOG-loaded MBG/poly(D,L-lactide) composite scaffolds (DMOG-MBG/PDLLA) for promoting bone repair. The effects of ultrasound stimulation and DMOG release on the cell responses of rat bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) and bone repair in vivo were investigated. Results and Discussion: The results showed that both ultrasound stimulation and DMOG release could promote the proliferation, adhesion and differentiation of BMSCs and HUVECs, respectively. After the implantation of scaffolds in rat cranial bone defect model for 8 weeks, the results indicated that the combined ultrasound stimulation and DMOG release contributed to the highest ability for promoting bone repair. Hence, the DMOG-MBG/PDLLA scaffolds with ultrasound stimulation are promising for application in bone repair.

Additive Manufacturing of Iron Carbide Incorporated Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug Delivery Applications

In this study, we have synthesized a bioactive glass with composition 45SiO2-20Na2O-23CaO-6P2O5-2.5B2O3-1ZnO-2MgO-0.5CaF2 (wt %). Further, it has been incorporated with 0.4 wt % iron carbide nanoparticles to prepare magnetic bioactive glass (MBG) with good heat generation capability for potential applications in magnetic field-assisted hyperthermia. The MBG scaffolds have been fabricated using extrusion-based additive manufacturing by mixing MBG powder with 25% Pluronic F-127 solution as the binder. The saturation magnetization of iron carbide nanoparticles in the bioactive glass matrix has been found to be 80 emu/g. The morphological analysis (pore size distribution, porosity, open pore network modeling, tortuosity, and pore interconnectivity) was done using an in-house developed methodology that revealed the suitability of the scaffolds for bone tissue engineering. The compressive strength (14.3 ± 1.6 MPa) of the MBG scaffold was within the range of trabecular bone. The in vitro test using simulated body fluid (SBF) showed the formation of apatite indicating the bioactive nature of scaffolds. Further, the drug delivery behaviors of uncoated and polycaprolactone (PCL) coated MBG scaffolds have been evaluated by loading an anticancer drug (Mitomycin C) onto the scaffolds. While the uncoated scaffold demonstrated the drug's burst release for the initial 80 h, the PCL-coated scaffold showed the gradual release of the drug. These results demonstrate the potential of the proposed MBG for bone tissue engineering and drug delivery applications.

Multidimensional 3D-Printed Scaffolds and Regeneration of Intrabony Periodontal Defects: A Systematic Review

BACKGROUND

The utilization of regenerative techniques in periodontology involves tailoring tissue engineering principles to suit the oral cavity's unique environment. Advancements in computer-assisted technology, specifically utilizing cone beam computed tomography (CBCT), enabled the fabrication of 3D-printed scaffolds. The current review aims to explore whether 3D-printed scaffolds are effective in promoting osteogenesis in patients with periodontal defects.

METHODS

A thorough exploration was undertaken across seven electronic databases (PubMed, Scopus, ScienceDirect, Google Scholar, Cochrane, Web of Science, Ovid) to detect pertinent research in accordance with specified eligibility criteria, aligning with the PRISMA guidelines. Two independent reviewers undertook the screening and selection of manuscripts, executed data extraction, and evaluated the bias risk using the Newcastle-Ottawa Scale for non-randomized clinical trials and SYRCLE's risk of bias tool for animal studies.

RESULTS

Initially, 799 articles were identified, refined by removing duplicates. After evaluating 471 articles based on title and abstract, 18 studies remained for full-text assessment. Eventually, merely two manuscripts fulfilled all the eligibility criteria concerning human trials. Both studies were prospective non-randomized clinical trials. Moreover, 11 animal studies were also included.

CONCLUSIONS

The use of multidimensional, 3D-printed, customized scaffolds appears to stimulate periodontal regeneration. While the reported results are encouraging, additional studies are required to identify the ideal characteristics of the 3D scaffold to be used in the regeneration of periodontal tissue.

Braided biomimetic PCL grafts for anterior cruciate ligament repair and regeneration

Anterior cruciate ligament (ACL) is a knee joint stabilizer with a limited regeneration capacity mainly because of low cellular content. State-of-the-art procedures are unable to restore the functions of the tissue as demonstrated by limited success rates. Regenerative engineering can offer a solution for restoring the functions of torn/ruptured ligaments provided that biomimetic grafts are available as grafts/scaffolds. However, a model construct to test behavior of cells to better understand the healing mechanism of ACL is still missing. This study, firstly, aimed at creating an injured rabbit ACL model. Then, the injured and healthy ACL tissues were characterized in terms of alignment and diameter distributions of collagen fibrils. Next, polycaprolactone (PCL) grafts were prepared from braided electrospun meshes and were characterized in terms of alignment and diameter distributions of fibers. Finally, biomechanical properties of ACL tissue and mechanical properties of PCL grafts were determined and compared. Findings demonstrated that distributions of the fiber diameters of PCL electrospun grafts were similar to diameter distribution of collagens of healthy and injured rabbit ACL. The novelty of this study relies on the determination of the diameter distribution of collagens of healthy and injured rabbit ACL tissues, and fabrication of PCL grafts with diameter distributions similar to that seen in healthy and injured ACLs. This study is significant because it addresses a worldwide clinical problem associated with millions of patients. The fibrous biomimetic graft designed in this study is different from the traditional grafts that exhibit unimodal distribution, and it is expected to have a significant contribution to ACL regeneration efforts.

Bioprinting: Mechanical Stabilization and Reinforcement Strategies in Regenerative Medicine

Bioprinting describes the printing of biomaterials and cell-laden or cell-free hydrogels with various combinations of embedded bioactive molecules. It encompasses the precise patterning of biomaterials and cells to create scaffolds for different biomedical needs. There are many requirements that bioprinting scaffolds face, and it is ultimately the interplay between the scaffold's structure, properties, processing, and performance that will lead to its successful translation. Among the essential properties that the scaffolds must possess-adequate and appropriate application-specific chemical, mechanical, and biological performance-the mechanical behavior of hydrogel-based bioprinted scaffolds is the key to their stable performance in vivo at the site of implantation. Hydrogels that typically constitute the main scaffold material and the medium for the cells and biomolecules are very soft, and often lack sufficient mechanical stability, which reduces their printability and, therefore, the bioprinting potential. The aim of this review article is to highlight the reinforcement strategies that are used in different bioprinting approaches to achieve enhanced mechanical stability of the bioinks and the printed scaffolds. Enabling stable and robust materials for the bioprinting processes will lead to the creation of truly complex and remarkable printed structures that could accelerate the application of smart, functional scaffolds in biomedical settings. Impact statement Bioprinting is a powerful tool for the fabrication of 3D structures and scaffolds for biomedical applications. It has gained tremendous attention in recent years, and the bioink library is expanding to include more and more material combinations. From the practical application perspective, different properties need to be considered, such as the printed structure's chemical, mechanical, and biological performances. Among these, the mechanical behavior of the printed constructs is critical for their successful translation into the clinic. The aim of this review article is to explore the different reinforcement strategies used for the mechanical stabilization of bioinks and bioprinted structures.

Efficacy analysis following polymer coated drug eluting stent and bare metal stent deployment for femoropopliteal arterial disease

OBJECTIVES

The objective is to assess the performance of the Eluvia polymer coated drug eluting stent (DES) compared to a bare metal stent (BMS) platform in patients with femoropopliteal arterial disease.

METHODS

This is a retrospective, single-center analysis. Patients treated with the Eluvia DES (group Eluvia) or the EverFlex BMS (group BMS) for femoropopliteal disease between January 2013 and December 2019 were included. Primary measure outcome of this analysis was the overall mortality. The PTX specific mortality, the primary patency, the amputation free survival (AFS), and the target lesion revascularization (TLR) rates were additionally evaluated.

RESULTS

A total of 124 patients were treated by BMS deployment, while the Eluvia platform was preferred in 75 subjects. In both groups the majority presented with lifestyle limiting claudication (BMS: 84% vs Eluvia: 73%, p = 0.73). Chronic total occlusions were more frequent in patients treated by BMS (BMS: 71% vs Eluvia: 84%, p = 0.027), whereas the calcification burden (BMS: 81% vs Eluvia: 76%, p = 0.43) and the median lesion length (in mm, IQR) (BMS: 160 (100 to 240) vs Eluvia: 140 (80 to 229), p = 0.17) were comparable. At 24 months, the overall survival (BMS: 93% vs Eluvia: 89%, hazard ratio (HR): 1.20, 95% confidence interval (CI): 0.55 to 2.64, p = 0.64) and the PTX specific survival (BMS: 95% vs Eluvia: 95%, HR: 1.28, 95% CI: 0.41 to 4.02, p = 0.67) did not differ significantly between the two platforms. No significant difference was observed regarding the 24 months primary patency rate (BMS: 66% vs Eluvia: 78%, HR: 0.65, 95% CI: 0.37 to 1.15, p = 0.18), the freedom from TLR (BMS: 83% vs Eluvia: 89%, HR: 0.81, 95% CI: 0.39 to 1.68, p = 0.572), and the AFS (BMS: 93 vs Eluvia: 89%, HR: 1.20, 95% CI: 0.55 to 2.64). The Cox regression analysis revealed a higher mortality risk among patients with chronic limb-threatening ischemia (CLTI) (HR: 3.14, 95% CI: 1.61 to 6.14, p = 0.008), chronic obstructive pulmonary disease (COPD) (HR: 4.65, 95% CI: 2.14 to 10.09, p = 0.001), in octagenerians (HR: 4.40, 95% CI: 1.92 to 10.44, p = 0.005), and in patients not on statins at baseline (HR: 2.44, 95% CI: 1.19 to 4.99, p=0.014).

CONCLUSIONS

In this cohort, the use of the Eluvia DES did not increase the risk for mortality compared to BMS deployment. CLTI, COPD, advanced age, and the lack of statin therapy at baseline were associated with a higher risk for death.

In vivo behavior in rabbit radius bone defect of scaffolds based on nanocarbonate hydroxyapatite

Bone defects treatment may require the use of biomaterials that behave as a support and promote bone regeneration. Limitations associated with the use of autografts and allografts make it necessary to design new synthetic bone substitutes. Some of the most promising biomaterials currently under investigation are based on nanocarbonate hydroxyapatite (nCHA). In this study, we studied the bone-inducing capacity of nCHA-based scaffolds alone (SAG) and enriched with osteostatin (SAGO) or with bone marrow aspirate(SAGB) after implantation for 12 weeks in a 15-mm long critical defect performed in the radius of New Zealand rabbits. Bone formation obtained was compared with a group with the unfilled defect (CE), as control group, and other with the defect filed with iliac crest autograft (GS), as gold standard. X-ray follow-up was performed at 2, 4, 6 and 12 weeks and μCT and histological studies at 12 weeks. The radiological results showed a greater increment in bone formation in the GS group (75%-100%), followed by the SAG and SAGB groups (50%-75%). μCT results showed an increase of bone volume/tissue volume values in GS group followed by SAG and SAGB groups (0.53, 0.40, and 0.31 respectively) compared with CE group (0.26). Histological results showed limited resorption of the nCHA scaffolds and partial osseointegration in the SAG and SAGB groups. However, in the SAGO group, the presence of connective tissue encapsulating the scaffold was detected. In SAG, SAGB, and increase of bone formation were observed compared with CE group, but less than the GS group. Thus, the investigated materials represent a significant advance in the design of synthetic materials for bone grafting, but further studies are needed to bring their in vivo behavior closer to autograft, the gold standard.

Chitosan-Based Biomaterial in Wound Healing: A Review

Wound healing is an evolving and intricate technique that is vital to the restoration of tissue integrity and function. Over the past few decades, chitosan a biopolymer derived from chitin, became known as an emerging biomaterial in the field of healing wounds due to its distinctive characteristics including biocompatibility, biodegradability, affinity to biomolecules, and wound-healing activity. This natural polymer exhibits excellent healing capabilities by accelerating the development of new skin cells, reducing inflammation, and preventing infections. Due to its distinct biochemical characteristics and innate antibacterial activity, chitosan has been extensively researched as an antibacterial wound dressing. Chronic wounds, such as diabetic ulcers and liver disease, are a growing medical problem. Chitosan-based biomaterials are a promising solution in the domain of wound care. The article analyzes the depth of chitosan-based biomaterials and their impact on wound healing and also the methods to enhance the advantages of chitosan by incorporating bioactive compounds. This literature review is aimed to improve the understanding and knowledge about biomaterials and their use in wound healing.

Advances in extracellular vesicle-based combination therapies for spinal cord injury

Spinal cord injury is a severe insult to the central nervous system that causes persisting neurological deficits. The currently available treatments involve surgical, medical, and rehabilitative strategies. However, none of these techniques can markedly reverse neurological deficits. Recently, extracellular vesicles from various cell sources have been applied to different models of spinal cord injury, thereby generating new cell-free therapies for the treatment of spinal cord injury. However, the use of extracellular vesicles alone is still associated with some notable shortcomings, such as their uncertainty in targeting damaged spinal cord tissues and inability to provide structural support to damaged axons. Therefore, this paper reviews the latest combined strategies for the use of extracellular vesicle-based technology for spinal cord injury, including the combination of extracellular vesicles with nanoparticles, exogenous drugs and/or biological scaffold materials, which facilitate the targeting ability of extracellular vesicles and the combinatorial effects with extracellular vesicles. We also highlight issues relating to the clinical transformation of these extracellular vesicle-based combination strategies for the treatment of spinal cord injury.

Features of Changes in the Structure and Properties of a Porous Polymer Material with Antibacterial Activity during Biodegradation in an In Vitro Model

Hybrid porous polymers based on poly-EGDMA and polylactide containing vancomycin, the concentration of which in the polymer varied by two orders of magnitude, were synthesized. The processes of polymer biodegradation and vancomycin release were studied in the following model media: phosphate-buffered saline (PBS), trypsin-Versene solution, and trypsin-PBS solution. The maximum antibiotic release was recorded during the first 3 h of extraction. The duration of antibiotic escape from the polymer samples in trypsin-containing media varied from 3 to 22 days, depending on the antibiotic content of the polymer. Keeping samples of the hybrid polymer in trypsin-containing model media resulted in acidification of the solutions-after 45 days, up to a pH of 1.84 in the trypsin-Versene solution and up to pH 1.65 in the trypsin-PBS solution. Here, the time dependences of the vancomycin release from the polymer into the medium and the decrease in pH of the medium correlated. These data are also consistent with the results of a study of the dynamics of sample weight loss during extraction in the examined model media. However, while the polymer porosity increased from ~53 to ~60% the pore size changed insignificantly, over only 10 μm. The polymer samples were characterized by their antibacterial activity against Staphylococcus aureus, and this activity persisted for up to 21 days during biodegradation of the material, regardless of the medium type used in model. Surface-dependent human cells (dermal fibroblasts) adhere well, spread out, and maintain high viability on samples of the functionalized hybrid polymer, thus demonstrating its biocompatibility in vitro.

Bioactive Polyurethane-Poly(ethylene Glycol) Diacrylate Hydrogels for Applications in Tissue Engineering

Polyurethanes (PUs) are a highly adaptable class of biomaterials that are among some of the most researched materials for various biomedical applications. However, engineered tissue scaffolds composed of PU have not found their way into clinical application, mainly due to the difficulty of balancing the control of material properties with the desired cellular response. A simple method for the synthesis of tunable bioactive poly(ethylene glycol) diacrylate (PEGDA) hydrogels containing photocurable PU is described. These hydrogels may be modified with PEGylated peptides or proteins to impart variable biological functions, and the mechanical properties of the hydrogels can be tuned based on the ratios of PU and PEGDA. Studies with human cells revealed that PU-PEG blended hydrogels support cell adhesion and viability when cell adhesion peptides are crosslinked within the hydrogel matrix. These hydrogels represent a unique and highly tailorable system for synthesizing PU-based synthetic extracellular matrices for tissue engineering applications.

Fluoride-Incorporated Apatite Coating on Collagen Sponge as a Carrier for Basic Fibroblast Growth Factor

Coating layers consisting of a crystalline apatite matrix with immobilized basic fibroblast growth factor (bFGF) can release bFGF, thereby enhancing bone regeneration depending on their bFGF content. We hypothesized that the incorporation of fluoride ions into apatite crystals would enable the tailored release of bFGF from the coating layer depending on the layer's fluoride content. In the present study, coating layers consisting of fluoride-incorporated apatite (FAp) crystals with immobilized bFGF were coated on a porous collagen sponge by a precursor-assisted biomimetic process using supersaturated calcium phosphate solutions with various fluoride concentrations. The fluoride content in the coating layer increased with the increasing fluoride concentration of the supersaturated solution. The increased fluoride content in the coating layer reduced its solubility and suppressed the burst release of bFGF from the coated sponge into a physiological salt solution. The bFGF release was caused by the partial dissolution of the coating layer and, thus, accompanied by the fluoride release. The concentrations of released bFGF and fluoride were controlled within the estimated effective ranges in enhancing bone regeneration. These findings provide useful design guidelines for the construction of a mineralized, bFGF-releasing collagen scaffold that would be beneficial for bone tissue engineering, although further in vitro and in vivo studies are warranted.

Characterization of Gelatin-Polycaprolactone Membranes by Electrospinning

New advances in materials science and medicine have enabled the development of new and increasingly sophisticated biomaterials. One of the most widely used biopolymers is polycaprolactone (PCL) because it has properties suitable for biomedical applications, tissue engineering scaffolds, or drug delivery systems. However, PCL scaffolds do not have adequate bioactivity, and therefore, alternatives have been studied, such as mixing PCL with bioactive polymers such as gelatin, to promote cell growth. Thus, this work will deal with the fabrication of nanofiber membranes by means of the electrospinning technique using PCL-based solutions (12 wt.% and 20 wt.%) and PCL with gelatin (12 wt.% and 8 wt.%, respectively). Formic acid and acetic acid, as well as mixtures of both in different proportions, have been used to prepare the preliminary solutions, thus supporting the electrospinning process by controlling the viscosity of the solutions and, therefore, the size and uniformity of the fibers. The physical properties of the solutions and the morphological, mechanical, and thermal properties of the membranes were evaluated. Results demonstrate that it is possible to achieve the determined properties of the samples with an appropriate selection of polymer concentrations as well as solvents.

A Combined Computational and Experimental Analysis of PLA and PCL Hybrid Nanocomposites 3D Printed Scaffolds for Bone Regeneration

A combined computational and experimental study of 3D-printed scaffolds made from hybrid nanocomposite materials for potential applications in bone tissue engineering is presented. Polycaprolactone (PCL) and polylactic acid (PLA), enhanced with chitosan (CS) and multiwalled carbon nanotubes (MWCNTs), were investigated in respect of their mechanical characteristics and responses in fluidic environments. A novel scaffold geometry was designed, considering the requirements of cellular proliferation and mechanical properties. Specimens with the same dimensions and porosity of 45% were studied to fully describe and understand the yielding behavior. Mechanical testing indicated higher apparent moduli in the PLA-based scaffolds, while compressive strength decreased with CS/MWCNTs reinforcement due to nanoscale challenges in 3D printing. Mechanical modeling revealed lower stresses in the PLA scaffolds, attributed to the molecular mass of the filler. Despite modeling challenges, adjustments improved simulation accuracy, aligning well with experimental values. Material and reinforcement choices significantly influenced responses to mechanical loads, emphasizing optimal structural robustness. Computational fluid dynamics emphasized the significance of scaffold permeability and wall shear stress in influencing bone tissue growth. For an inlet velocity of 0.1 mm/s, the permeability value was estimated at 4.41 × 10-9 m2, which is in the acceptable range close to human natural bone permeability. The average wall shear stress (WSS) value that indicates the mechanical stimuli produced by cells was calculated to be 2.48 mPa, which is within the range of the reported literature values for promoting a higher proliferation rate and improving osteogenic differentiation. Overall, a holistic approach was utilized to achieve a delicate balance between structural robustness and optimal fluidic conditions, in order to enhance the overall performance of scaffolds in tissue engineering applications.

Beyond Vision: An Overview of Regenerative Medicine and Its Current Applications in Ophthalmological Care

Regenerative medicine (RM) has emerged as a promising and revolutionary solution to address a range of unmet needs in healthcare, including ophthalmology. Moreover, RM takes advantage of the body's innate ability to repair and replace pathologically affected tissues. On the other hand, despite its immense promise, RM faces challenges such as ethical concerns, host-related immune responses, and the need for additional scientific validation, among others. The primary aim of this review is to present a high-level overview of current strategies in the domain of RM (cell therapy, exosomes, scaffolds, in vivo reprogramming, organoids, and interspecies chimerism), centering around the field of ophthalmology. A search conducted on clinicaltrials.gov unveiled a total of at least 209 interventional trials related to RM within the ophthalmological field. Among these trials, there were numerous early-phase studies, including phase I, I/II, II, II/III, and III trials. Many of these studies demonstrate potential in addressing previously challenging and degenerative eye conditions, spanning from posterior segment pathologies like Age-related Macular Degeneration and Retinitis Pigmentosa to anterior structure diseases such as Dry Eye Disease and Limbal Stem Cell Deficiency. Notably, these therapeutic approaches offer tailored solutions specific to the underlying causes of each pathology, thus allowing for the hopeful possibility of bringing forth a treatment for ocular diseases that previously seemed incurable and significantly enhancing patients' quality of life. As advancements in research and technology continue to unfold, future objectives should focus on ensuring the safety and prolonged viability of transplanted cells, devising efficient delivery techniques, etc.

Magnetic Alignment of Collagen: Principles, Methods, Applications, and Fiber Alignment Analyses

Anisotropically aligned collagen scaffolds mimic the microarchitectural properties of native tissue, possess superior mechanical properties, and provide the essential physicochemical cues to guide cell response. Biofabrication methodologies to align collagen fibers include mechanical, electrical, magnetic, and microfluidic approaches. Magnetic alignment of collagen was first published in 1983 but widespread use of this technique was hindered mainly due to the low diamagnetism of collagen molecules and the need for very strong tesla-order magnetic fields. Over the last decade, there is a renewed interest in the use of magnetic approaches that employ magnetic particles and low-level magnetic fields to align collagen fibers. In this review, the working principle, advantages, and limitations of different collagen alignment techniques with special emphasis on the magnetic alignment approach are detailed. Key findings from studies that employ high-strength magnetic fields and the magnetic particle-based approach to align collagen fibers are highlighted. In addition, the most common qualitative and quantitative image analyses methods to assess collagen alignment are discussed. Finally, current challenges and future directions are presented for further development and clinical translation of magnetically aligned collagen scaffolds.

Hydrogel Composite Magnetic Scaffolds: Toward Cell-Free In Situ Bone Tissue Engineering

Reconstruction of critical sized bone defects in the oral and maxillofacial region continues to be clinically challenging despite the significant development of osteo-regenerative materials. Among 3D biomaterials, hydrogels and hydrogel composites have been explored for bone regeneration, however, their inferior clinical performance in comparison to autografts is mainly attributed to variable rates of degradation and lack of vascularization. In this study, we report hydrogel composite magnetic scaffolds formed from calcium carbonate, poly(vinyl alcohol) (PVA), and magnetic nanoparticles (MNPs), using PVA as matrix and calcium carbonate particles in vaterite phase as filler, to enhance the cross-linking of matrix and porosity with MNPs that can target and regulate cell signaling pathways to control cell behavior and improve the osteogenic and angiogenic potential. The physical and mechanical properties were evaluated, and cytocompatibility was investigated by culturing human osteoblast-like cells onto the scaffolds. The vaterite phase due to its higher solubility in comparison to calcium phosphates, combined with the freezing-thawing process of PVA, yielded porous scaffolds that exhibited adequate thermal stability, favorable water-absorbing capacity, excellent mineralization ability, and cytocompatibility. An increasing concentration from 1, 3, and 6 wt % MNPs in the scaffolds showed a statistically significant increase in compressive strength and modulus of the dry specimens that exhibited brittle fracture. However, the hydrated specimens were compressible and showed a slight decrease in compressive strength with 6% MNPs, although this value was higher compared to that of the scaffolds with no MNPs.

Photobiomodulation Therapy Improves Repair of Bone Defects Filled by Inorganic Bone Matrix and Fibrin Heterologous Biopolymer

Biomaterials are used extensively in graft procedures to correct bone defects, interacting with the body without causing adverse reactions. The aim of this pre-clinical study was to analyze the effects of photobiomodulation therapy (PBM) with the use of a low-level laser in the repair process of bone defects filled with inorganic matrix (IM) associated with heterologous fibrin biopolymer (FB). A circular osteotomy of 4 mm in the left tibia was performed in 30 Wistar male adult rats who were randomly divided into three groups: G1 = IM + PBM, G2 = IM + FB and G3 = IM + FB + PBM. PBM was applied at the time of the experimental surgery and three times a week, on alternate days, until euthanasia, with 830 nm wavelength, in two points of the operated site. Five animals from each group were euthanized 14 and 42 days after surgery. In the histomorphometric analysis, the percentage of neoformed bone tissue in G3 (28.4% ± 2.3%) was higher in relation to G1 (24.1% ± 2.91%) and G2 (22.2% ± 3.11%) at 14 days and at 42 days, the percentage in G3 (35.1% ± 2.55%) was also higher in relation to G1 (30.1% ± 2.9%) and G2 (31.8% ± 3.12%). In the analysis of the birefringence of collagen fibers, G3 showed a predominance of birefringence between greenish-yellow in the neoformed bone tissue after 42 days, differing from the other groups with a greater presence of red-orange fibers. Immunohistochemically, in all experimental groups, it was possible to observe immunostaining for osteocalcin (OCN) near the bone surface of the margins of the surgical defect and tartrate-resistant acid phosphatase (TRAP) bordering the newly formed bone tissue. Therefore, laser photobiomodulation therapy contributed to improving the bone repair process in tibial defects filled with bovine biomaterial associated with fibrin biopolymer derived from snake venom.

Tailoring the Heterogeneous Structure of Macro-Fibers Assembled by Bacterial Cellulose Nanofibrils for Tissue Engineering Scaffolds

Bacterial cellulose/oxidized bacterial cellulose nanofibrils (BC/oxBCNFs) macro-fibers are developed as a novel scaffold for vascular tissue engineering. Utilizing a low-speed rotary coagulation spinning technique and precise solvent control, macro-fibers with a unique heterogeneous structure with dense surface and porous core are created. Enhanced by a polydopamine (PDA) coating, these macro-fibers offer robust mechanical integrity, high biocompatibility, and excellent cell adhesion. When cultured with endothelial cells (ECs) and smooth muscle cells (SMCs), the macro-fibers support healthy cell proliferation and exhibit a unique spiral SMC alignment, demonstrating their vascular suitability. This innovative strategy opens new avenues for advances in tissue engineering.

Cellular Senescence Program is Sensitive to Physical Differences in Polymeric Tissue Scaffolds

A typical cellular senescence program involves exposing cells to DNA-damaging agents such as ionization radiation or chemotherapeutic drugs, which cause multipronged changes, including increased cell size and volume, the onset of enhanced oxidative stress, and inflammation. In the present study, we examined if the senescence onset decision is sensitive to the design, porosity, and architecture of the substrate. To address this, we generated a library of polymeric scaffolds widely used in tissue engineering of varied stiffness, architecture, and porosity. Using irradiated A549 lung cancer cells, we examined the differences between cellular responses in these 3D scaffold systems and observed that senescence onset is equally diminished. When compared to the two-dimensional (2D) culture formats, there were profound changes in cell size and senescence induction in three-dimensional (3D) scaffolds. We further establish that these observed differences in the senescence state can be attributed to the altered cell spreading and cellular interactions on these substrates. This study elucidates the role of scaffold architecture in the cellular senescence program.

Global research trends and hotspots on tendon-derived stem cell: a bibliometric visualization study

Purpose: This study was aimed to examine the global research status and current research hotspots in the field of tendon stem cells. Methods: Bibliometric methods were employed to retrieve relevant data from the Web of Science Core Collection (WOSCC) database. Additionally, Citespace, Vosviewer, SCImago, and Graphad Prism were utilized to analyze the publication status in this field, identify the current research hotspots, and present a mini-review. Results: The most active countries in this field were China and the United States. Notable authors contributing significantly to this research included Lui Pauline Po Yee, Tang Kanglai, Zhang Jianying, Yin Zi, and Chen Xiao, predominantly affiliated with institutions such as the Hong Kong Hospital Authority, Third Military Medical University, University of Pittsburgh, and Zhejiang University. The most commonly published journals in this field were Stem Cells International, Journal of Orthopedic Research, and Stem Cell Research and Therapy. Moreover, the current research hotspots primarily revolved around scaffolds, molecular mechanisms, and inflammation regulation. Conclusion: Tendon stem cells hold significant potential as seed cells for tendon tissue engineering and offer promising avenues for further research Scaffolds, molecular mechanisms and inflammation regulation are currently research hotspots in this field.

Conducting polymer scaffolds: a new frontier in bioelectronics and bioengineering

Conducting polymer (CP) scaffolds have emerged as a transformative tool in bioelectronics and bioengineering, advancing the ability to interface with biological systems. Their unique combination of electrical conductivity, tailorability, and biocompatibility surpasses the capabilities of traditional nonconducting scaffolds while granting them access to the realm of bioelectronics. This review examines recent developments in CP scaffolds, focusing on material and device advancements, as well as their interplay with biological systems. We highlight applications for monitoring, tissue stimulation, and drug delivery and discuss perspectives and challenges currently faced for their ultimate translation and clinical implementation.

Biomimetic Scaffolds Based on Mn2+-, Mg2+-, and Sr2+-Substituted Calcium Phosphates Derived from Natural Sources and Polycaprolactone

The occurrence of bone disorders is steadily increasing worldwide. Bone tissue engineering (BTE) has emerged as a promising alternative to conventional treatments of bone defects, developing bone scaffolds capable of promoting bone regeneration. In this research, biomimetic scaffolds based on ion-substituted calcium phosphates, derived from cuttlefish bone, were prepared using a hydrothermal method. To synthesize Mn2+-substituted scaffolds, three different manganese concentrations (corresponding to 1, 2.5, and 5 mol% Mn substitutions for Ca into hydroxyapatite) were used. Also, syntheses with the simultaneous addition of an equimolar amount (1 mol%) of two (Mg2+ and Sr2+) or three ions (Mn2+, Mg2+, and Sr2+) were performed. A chemical, structural, and morphological characterization was carried out using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effects of the ion substitutions on the lattice parameters, crystallite sizes, and fractions of the detected phases were discussed. Multi-substituted (Mn2+, Mg2+, and Sr2+) scaffolds were coated with polycaprolactone (PCL) using simple vacuum impregnation. The differentiation of human mesenchymal stem cells (hMSCs), cultured on the PCL-coated scaffold, was evaluated using histology, immunohistochemistry, and reverse transcription-quantitative polymerase chain reaction analyses. The expression of collagen I, alkaline phosphatase, and dentin matrix protein 1 was detected. The influence of PCL coating on hMSCs behavior is discussed.

A Supramolecular Injectable Methacryloyl Chitosan-Tricine-Based Hydrogel with 3D Printing Potential for Tissue Engineering Applications

Printable hydrogels have attracted significant attention as versatile, tunable, and spatiotemporally controlled biomaterials for tissue engineering (TE) applications. Several chitosan-based systems are reported presenting low or no solubility in aqueous solutions at physiological pH. Herein, a novel neutrally charged, biomimetic, injectable, and cytocompatible dual-crosslinked (DC) hydrogel system based on a double functionalized chitosan (CHT) with methacryloyl and tricine moieties (CHTMA-Tricine), completely processable at physiological pH, with promising three-dimensional (3D) printing potential is presented. Tricine, an amino acid typically used in biomedicine, is capable of establishing supramolecular interactions (H-bonds) and is never explored as a hydrogel component for TE. CHTMA-Tricine hydrogels demonstrate significantly greater toughness (ranging from 656.5 ± 82.2 to 1067.5 ± 121.5 kJ m-3 ) compared to CHTMA hydrogels (ranging from 382.4 ± 44.1 to 680.8 ± 104.5 kJ m-3 ), highlighting the contribution of the supramolecular interactions for the overall reinforced 3D structure provided by tricine moieties. Cytocompatibility studies reveal that MC3T3-E1 pre-osteoblasts cells remain viable for 6 days when encapsulated in CHTMA-Tricine constructs, with semi-quantitative analysis showing ≈80% cell viability. This system's interesting viscoelastic properties allow the fabrication of multiple structures, which couple with a straightforward approach, will open doors for the design of advanced chitosan-based biomaterials through 3D bioprinting for TE.

Combining Step-Growth and Chain-Growth Polymerizations in One Pot: Light-Induced Fabrication of Conductive Nanoporous PEDOT-PCL Scaffold

A novel method based on light-induced fabrication of a poly (3,4-ethylenedioxythiophene)-polycaprolactone (PEDOT-PCL) scaffold using phenacyl bromide (PAB) as a single-component photoinitiator is presented. HBr released from the step-growth polymerization of EDOT is utilized as an in situ catalyst for the chain-growth polymerization of ε-caprolactone. Detailed investigations disclose the formation of a self-assembled nanoporous electroconductive scaffold (1.2 mS cm-1 ). Fluorescence emission spectra of the fabricated scaffold exhibit a mixed solvatochromic behavior, indicating specific interactions between the self-assembled scaffold and solvents with varying polarities, as evidenced by transmission electron microscopy (TEM). Moreover, the same light-induced technique can also be applied for bulk photopolymerization showcasing the versatility and wide-ranging scope of the originated method. In brief, this study introduces a novel approach for light-induced polymerization reactions that is merging step-growth and chain-growth mechanisms. This innovative approach is promising to facilitate in situ polymerization of monomers possessing diverse functionalities.

Applications of Scaffolds in Tissue Engineering: Current Utilization and Future Prospective

Current regenerative medicine tactics focus on regenerating tissue structures pathologically modified by cell transplantation in combination with supporting scaffolds and biomolecules. Natural and synthetic polymers, bioresorbable inorganic and hybrid materials, and tissue decellularized were deemed biomaterials scaffolding because of their improved structural, mechanical, and biological abilities.Various biomaterials, existing treatment methodologies and emerging technologies in the field of Three-dimensional (3D) and hydrogel processing, and the unique fabric concerns for tissue engineering. A scaffold that acts as a transient matrix for cell proliferation and extracellular matrix deposition, with subsequent expansion, is needed to restore or regenerate the tissue. Diverse technologies are combined to produce porous tissue regenerative and tailored release of bioactive substances in applications of tissue engineering. Tissue engineering scaffolds are crucial ingredients. This paper discusses an overview of the various scaffold kinds and their material features and applications. Tabulation of the manufacturing technologies for fabric engineering and equipment, encompassing the latest fundamental and standard procedures.

Advancements in scaffold for treating ligament injuries; in vitro evaluation

Tendon/ligament (T/L) injuries are a worldwide health problem that affects millions of people annually. Due to the characteristics of tendons, the natural rehabilitation of their injuries is a very complex and lengthy process. Surgical treatment of a T/L injury frequently necessitates using autologous or allogeneic grafts or synthetic materials. Nonetheless, these alternatives have limitations in terms of mechanical properties and histocompatibility, and they do not permit the restoration of the original biological function of the tissue, which can negatively impact the patient's quality of life. It is crucial to find biological materials that possess the necessary properties for the successful surgical treatment of tissues and organs. In recent years, the in vitro regeneration of tissues and organs from stem cells has emerged as a promising approach for preparing autologous tissue and organs, and cell culture scaffolds play a critical role in this process. However, the biological traits and serviceability of different materials used for cell culture scaffolds vary significantly, which can impact the properties of the cultured tissues. Therefore, this review aims to analyze the differences in the biological properties and suitability of various materials based on scaffold characteristics such as cell compatibility, degradability, textile technologies, fiber arrangement, pore size, and porosity. This comprehensive analysis provides valuable insights to aid in the selection of appropriate scaffolds for in vitro tissue and organ culture.