Nature-Inspired Unconventional Approaches to Develop 3D Bioceramic Scaffolds with Enhanced Regenerative Ability

Distal femoral bone defect treatment using an engineered hydroxyapatite cylinder scaffold made from rattan wood

Distal femoral non-union presents significant challenges, often requiring complex treatment strategies to achieve bone healing. In this case, a young male patient with an open fracture of the distal femur developed an atrophic non-union, 9 months after initial fixation. The patient underwent surgical intervention with debridement, leading to a 2.2 cm bone defect and placement of a cylindrical synthetic bone graft (b.Bone), combined with bone marrow aspirate concentrate. This approach aimed to provide structural support and enhance biological healing. The choice of the cylindrical graft was due to its optimal fit and support for the anterior femoral cortex. Postoperative outcomes were favourable, with successful bone healing, confirmed radiologically, and restoration of function. This case demonstrates the potential of synthetic bone substitutes augmented with biological agents as a promising alternative to traditional grafts in managing complex non-unions.

Collagen-hydroxyapatite based scaffolds for bone trauma and regeneration: recent trends and future perspectives

Regenerative therapy, a key area of tissue engineering, holds promise for restoring damaged organs, especially in bone regeneration. Bone healing is natural to the body but becomes complex under stress and disease. Large bone deformities pose significant challenges in tissue engineering. Among various methods, scaffolds are attractive as they provide structural support and essential nutrients for cell adhesion and growth. Collagen and hydroxyapatite (HA) are widely used due to their biocompatibility and biodegradability. Collagen and nano-scale HA enhance cell adhesion and development. Thus, nano HA/collagen scaffolds offer potential solutions for bone regeneration. This review focuses on the use and production of nano-sized HA/collagen composites in bone regeneration.

Preliminary osteogenic and antibacterial investigations of wood derived antibiotic-loaded bone substitute for the treatment of infected bone defects

Introduction: The development of reliable treatments for infected or potentially infected bone loss resulting from open fractures and non-unions is extremely urgent, especially to reduce the prolonged courses of antimicrobial therapy to which affected patients are subjected. Numerous bone graft substitutes have been used over the years, but there are currently no effective solutions to treat critical bone loss, especially in the presence of infection. The present study evaluated the use of the biomorphic calcium phosphate bone scaffold b. Bone™, based on a next-generation resorbable biomimetic biomaterial, in bone reconstruction surgery in cases of infection. Methods: Using an "in vitro 3D bone fracture model" to predict the behavior of this drug delivery system during critical bone loss at an infected (or potentially infected) site, the effects of scaffolds loaded with gentamicin or vancomycin on the viability and differentiation capacity of human mesenchymal stem cells (hMSCs) were evaluated. Results: This scaffold, when loaded with gentamicin or vancomycin, exhibits a typical drug release curve that determines the inhibitory effects on the growth of Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli, as well as relative biofilm formation. Discussion: The study demonstrates that b.bone scaffolds can effectively address key challenges in orthopedic surgery and patient care by inhibiting bacterial growth and biofilm formation through rapid, potent antibiotic release, reducing the risk of treatment failure due to resistance, and providing a promising solution for bone infections and improved patient outcomes. Future studies could explore the combination of different antibiotics on these scaffolds for more tailored and effective treatments against post-traumatic osteomyelitis pathogens.

A natural biogenic fluorapatite as a new biomaterial for orthopedics and dentistry: antibacterial activity of lingula seashell and its use for nanostructured biomimetic coatings

Calcium phosphates are widely studied in orthopedics and dentistry, to obtain biomimetic and antibacterial implants. However, the multi-substituted composition of mineralized tissues is not fully reproducible from synthetic procedures. Here, for the first time, we investigate the possible use of a natural, fluorapatite-based material, i.e., Lingula anatina seashell, resembling the composition of bone and enamel, as a biomaterial source for orthopedics and dentistry. Indeed, thanks to its unique mineralization process and conditions, L. anatina seashell is among the few natural apatite-based shells, and naturally contains ions having possible antibacterial efficacy, i.e., fluorine and zinc. After characterization, we explore its deposition by ionized jet deposition (IJD), to obtain nanostructured coatings for implantable devices. For the first time, we demonstrate that L. anatina seashells have strong antibacterial properties. Indeed, they significantly inhibit planktonic growth and cell adhesion of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The two strains show different susceptibility to the mineral and organic parts of the seashells, the first being more susceptible to zinc and fluorine in the mineral part, and the second to the organic (chitin-based) component. Upon deposition by IJD, all films exhibit a nanostructured morphology and sub-micrometric thickness. The multi-doped, complex composition of the target is maintained in the coating, demonstrating the feasibility of deposition of coatings starting from biogenic precursors (seashells). In conclusion, Lingula seashell-based coatings are non-cytotoxic with strong antimicrobial capability, especially against Gram-positive strains, consistently with their higher susceptibility to fluorine and zinc. Importantly, these properties are improved compared to synthetic fluorapatite, showing that the films are promising for antimicrobial applications.

Polysaccharide-bioceramic composites for bone tissue engineering: A review

Limitations associated with conventional bone substitutes such as autografts, increasing demand for bone grafts, and growing elderly population worldwide necessitate development of unique materials as bone graft substitutes. Bone tissue engineering (BTE) would ensure therapy advancement, efficiency, and cost-effective treatment modalities of bone defects. One way of engineering bone tissue scaffolds by mimicking natural bone tissue composed of organic and inorganic phases is to utilize polysaccharide-bioceramic hybrid composites. Polysaccharides are abundant in nature, and present in human body. Biominerals, like hydroxyapatite are present in natural bone and some of them possess osteoconductive and osteoinductive properties. Ion doped bioceramics could substitute protein-based biosignal molecules to achieve osteogenesis, vasculogenesis, angiogenesis, and stress shielding. This review is a systemic summary on properties, advantages, and limitations of polysaccharide-bioceramic/ion doped bioceramic composites along with their recent advancements in BTE.

Latest Research of Doped Hydroxyapatite for Bone Tissue Engineering

Bone tissue engineering has attracted great interest in the last few years, as the frequency of tissue-damaging or degenerative diseases has increased exponentially. To obtain an ideal treatment solution, researchers have focused on the development of optimum biomaterials to be applied for the enhancement of bioactivity and the regeneration process, which are necessary to support the proper healing process of osseous tissues. In this regard, hydroxyapatite (HA) has been the most widely used material in the biomedical field due to its great biocompatibility and similarity with the native apatite from the human bone. However, HA still presents some deficiencies related to its mechanical properties, which are essential for HA to be applied in load-bearing applications. Bioactivity is another vital property of HA and is necessary to further improve regeneration and antibacterial activity. These drawbacks can be solved by doping the material with trace elements, adapting the properties of the material, and, finally, sustaining bone regeneration without the occurrence of implant failure. Considering these aspects, in this review, we have presented some general information about HA properties, synthesis methods, applications, and the necessity for the addition of doping ions into its structure. Also, we have presented their influence on the properties of HA, as well as the latest applications of doped materials in the biomedical field.

Advanced applications of strontium-containing biomaterials in bone tissue engineering

Strontium (Sr) and strontium ranelate (SR) are commonly used therapeutic drugs for patients suffering from osteoporosis. Researches have showed that Sr can significantly improve the biological activity and physicochemical properties of materials in vitro and in vivo. Therefore, a large number of strontium containing biomaterials have been developed for repairing bone defects and promoting osseointegration. In this review, we provide a comprehensive overview of Sr-containing biomaterials along with the current state of their clinical use. For this purpose, the different types of biomaterials including calcium phosphate, bioactive glass, and polymers are discussed and provided future outlook on the fabrication of the next-generation multifunctional and smart biomaterials.

HYDRHA: Hydrogels of hyaluronic acid. New biomedical approaches in cancer, neurodegenerative diseases, and tissue engineering

In the last decade, hyaluronic acid (HA) has attracted an ever-growing interest in the biomedical engineering field as a biocompatible, biodegradable, and chemically versatile molecule. In fact, HA is a major component of the extracellular matrix (ECM) and is essential for the maintenance of cellular homeostasis and crosstalk. Innovative experimental strategies in vitro and in vivo using three-dimensional (3D) HA systems have been increasingly reported in studies of diseases, replacement of tissue and organ damage, repairing wounds, and encapsulating stem cells for tissue regeneration. The present work aims to give an overview and comparison of recent work carried out on HA systems showing advantages, limitations, and their complementarity, for a comprehensive characterization of their use. A special attention is paid to the use of HA in three important areas: cancer, diseases of the central nervous system (CNS), and tissue regeneration, discussing the most innovative experimental strategies. Finally, perspectives within and beyond these research fields are discussed.

Standardized and axially vascularized calcium phosphate-based implants for segmental mandibular defects: A promising proof of concept

The reconstruction of massive segmental mandibular bone defects (SMDs) remains challenging even today; the current gold standard in human clinics being vascularized bone transplantation (VBT). As alternative to this onerous approach, bone tissue engineering strategies have been widely investigated. However, they displayed limited clinical success, particularly in failing to address the essential problem of quick vascularization of the implant. Although routinely used in clinics, the insertion of intrinsic vascularization in bioengineered constructs for the rapid formation of a feeding angiosome remains uncommon. In a clinically relevant model (sheep), a custom calcium phosphate-based bioceramic soaked with autologous bone marrow and perfused by an arteriovenous loop was tested to regenerate a massive SMD and was compared to VBT (clinical standard). Animals did not support well the VBT treatment, and the study was aborted 2 weeks after surgery due to ethical and animal welfare considerations. SMD regeneration was successful with the custom vascularized bone construct. Implants were well osseointegrated and vascularized after only 3 months of implantation and totally entrapped in lamellar bone after 12 months; a healthy yellow bone marrow filled the remaining space. STATEMENT OF SIGNIFICANCE: Regenerative medicine struggles with the generation of large functional bone volume. Among them segmental mandibular defects are particularly challenging to restore. The standard of care, based on bone free flaps, still displays ethical and technical drawbacks (e.g., donor site morbidity). Modern engineering technologies (e.g., 3D printing, digital chain) were combined to relevant surgical techniques to provide a pre-clinical proof of concept, investigating for the benefits of such a strategy in bone-related regenerative field. Results proved that a synthetic-biologics-free approach is able to regenerate a critical size segmental mandibular defect of 15 cm³ in a relevant preclinical model, mimicking real life scenarii of segmental mandibular defect, with a full physiological regeneration of the defect after 12 months.

Proteomic Analysis of Decellularized Extracellular Matrix: Achieving a Competent Biomaterial for Osteogenesis

Decellularized ECMs have been used as biological scaffolds for tissue repair due to their tissue-specific biochemical and mechanical composition, poorly simulated by other materials. It is used as patches and powders, and it could be further processed via enzymatic digestion under acidic conditions using pepsin. However, part of the bioactivity is lost during the digestion process due to protein denaturation. Here, stepwise digestion was developed to prepare a competent biomaterial for osteogenesis from three different ECM sources. In addition, three different proteases were compared to evaluate the most effective digestion protocol for specific cellular processes. GAGs and peptide quantification showed that the stepwise method yielded a higher concentration of bioactive residues. Circular dichroism analysis also showed that the stepwise approach preserved the secondary structures better. The protein profiles of the digested ECMs were analyzed, and it was found to be highly diverse and tissue-specific. The digestion of ECM from pericardium produced peptides originated from 94 different proteins, followed by 48 proteins in ECM from tendon and 35 proteins in ECM from bone. In addition, digested products from pericardium ECM yielded increased proliferation and differentiation of bone marrow mesenchymal stem cells to mature osteoblasts.

Application of Nano-Inspired Scaffolds-Based Biopolymer Hydrogel for Bone and Periodontal Tissue Regeneration

This review's objectives are to provide an overview of the various kinds of biopolymer hydrogels that are currently used for bone tissue and periodontal tissue regeneration, to list the advantages and disadvantages of using them, to assess how well they might be used for nanoscale fabrication and biofunctionalization, and to describe their production processes and processes for functionalization with active biomolecules. They are applied in conjunction with other materials (such as microparticles (MPs) and nanoparticles (NPs)) and other novel techniques to replicate physiological bone generation more faithfully. Enhancing the biocompatibility of hydrogels created from blends of natural and synthetic biopolymers can result in the creation of the best scaffold match to the extracellular matrix (ECM) for bone and periodontal tissue regeneration. Additionally, adding various nanoparticles can increase the scaffold hydrogel stability and provide a number of biological effects. In this review, the research study of polysaccharide hydrogel as a scaffold will be critical in creating valuable materials for effective bone tissue regeneration, with a future impact predicted in repairing bone defects.

Design Strategies and Biomimetic Approaches for Calcium Phosphate Scaffolds in Bone Tissue Regeneration

Bone is a complex biologic tissue, which is extremely relevant for various physiological functions, in addition to movement, organ protection, and weight bearing. The repair of critical size bone defects is a still unmet clinical need, and over the past decades, material scientists have been expending efforts to find effective technological solutions, based on the use of scaffolds. In this context, biomimetics which is intended as the ability of a scaffold to reproduce compositional and structural features of the host tissues, is increasingly considered as a guide for this purpose. However, the achievement of implants that mimic the very complex bone composition, multi-scale structure, and mechanics is still an open challenge. Indeed, despite the fact that calcium phosphates are widely recognized as elective biomaterials to fabricate regenerative bone scaffolds, their processing into 3D devices with suitable cell-instructing features is still prevented by insurmountable drawbacks. With respect to biomaterials science, new approaches maybe conceived to gain ground and promise for a substantial leap forward in this field. The present review provides an overview of physicochemical and structural features of bone tissue that are responsible for its biologic behavior. Moreover, relevant and recent technological approaches, also inspired by natural processes and structures, are described, which can be considered as a leverage for future development of next generation bioactive medical devices.

The Osteoinductivity of Calcium Phosphate-Based Biomaterials: A Tight Interaction With Bone Healing

Calcium phosphate (CaP)-based bioceramics are the most widely used synthetic biomaterials for reconstructing damaged bone. Accompanied by bone healing process, implanted materials are gradually degraded while bone ultimately returns to its original geometry and function. In this progress report, we reviewed the complex and tight relationship between the bone healing response and CaP-based biomaterials, with the emphasis on the in vivo degradation mechanisms of such material and their osteoinductive properties mediated by immune responses, osteoclastogenesis and osteoblasts. A deep understanding of the interaction between biological healing process and biomaterials will optimize the design of CaP-based biomaterials, and further translate into effective strategies for biomaterials customization.

New Ground-Breaking Strategies in Bone Regeneration—In Memory of Nerio Ceroni

This editorial article is dedicated to the memory of the Nerio Ceroni, the grandfather of the first author [...]

Evaluation of Human Bone Marrow Mesenchymal Stromal Cell (MSC) Functions on a Biomorphic Rattan-Wood-Derived Scaffold: A Comparison between Cultured and Uncultured MSCs

The reconstruction of large bone defects requires the use of biocompatible osteoconductive scaffolds. These scaffolds are often loaded with the patient’s own bone marrow (BM) cells to facilitate osteoinductivity and biological potency. Scaffolds that are naturally sourced and fabricated through biomorphic transitions of rattan wood (B-HA scaffolds) offer a unique advantage of higher mechanical strength and bioactivity. In this study, we investigated the ability of a biomorphic B-HA scaffold (B-HA) to support the attachment, survival and gene expression profile of human uncultured BM-derived mesenchymal stromal cells (BMSCs, n = 6) and culture expanded MSCs (cMSCs, n = 7) in comparison to a sintered, porous HA scaffold (S-HA). B-HA scaffolds supported BMSC attachment (average 98%) and their survival up to 4 weeks in culture. Flow cytometry confirmed the phenotype of cMSCs on the scaffolds. Gene expression indicated clear segregation between cMSCs and BMSCs with MSC osteogenesis- and adipogenesis-related genes including RUNX2, PPARγ, ALP and FABP4 being higher expressed in BMSCs. These data indicated a unique transcriptional signature of BMSCs that was distinct from that of cMSCs regardless of the type of scaffold or time in culture. There was no statistical difference in the expression of osteogenic genes in BMSCs or cMSCs in B-HA compared to S-HA. VEGF release from cMSCs co-cultured with human endothelial cells (n = 4) on B-HA scaffolds suggested significantly higher supernatant concentration with endothelial cells on day 14. This indicated a potential mechanism for providing vasculature to the repair area when such scaffolds are used for treating large bone defects.