Hybrid bioactive hydroxyapatite/polycaprolactone nanoparticles for enhanced osteogenesis

Alendronate/lactoferrin-dual decorated lipid nanocarriers for bone-homing and active targeting of ivermectin and methyl dihydrojasmonate for leukemia

Chronic myeloid leukemia is a hematological cancer, where disease relapse and drug resistance are caused by bone-hosted-residual leukemia cells. An innovative resolution is bone-homing and selective-active targeting of anticancer loaded-nanovectors. Herein, ivermectin (IVM) and methyl dihydrojasmonate (MDJ)-loaded nanostructured lipid carriers (IVM-NLC) were formulated then dually decorated by lactoferrin (Lf) and alendronate (Aln) to optimize (Aln/Lf/IVM-NLC) for active-targeting and bone-homing potential, respectively. Aln/Lf/IVM-NLC (1 mg) revealed nano-size (73.67 ± 0.06 nm), low-PDI (0.43 ± 0.06), sustained-release of IVM (62.75 % at 140-h) and MDJ (78.7 % at 48-h). Aln/Lf/IVM-NLC afforded substantial antileukemic-cytotoxicity on K562-cells (4.29-fold lower IC50), higher cellular uptake and nuclear fragmentation than IVM-NLC with acceptable cytocompatibility on oral-epithelial-cells (as normal cells). Aln/Lf/IVM-NLC effectively upregulated caspase-3 and BAX (4.53 and 15.9-fold higher than IVM-NLC, respectively). Bone homing studies verified higher hydroxyapatite affinity of Aln/Lf/IVM-NLC (1 mg; 22.88 ± 0.01 % at 3-h) and higher metaphyseal-binding (1.5-fold increase) than untargeted-NLC. Moreover, Aln/Lf/IVM-NLC-1 mg secured 1.35-fold higher in vivo bone localization than untargeted-NLC, with lower off-target distribution. Ex-vivo hemocompatibility and in-vivo biocompatibility of Aln/Lf/IVM-NLC (1 mg/mL) were established, with pronounced amelioration of hepatic and renal toxicity compared to higher Aln doses. The innovative Aln/Lf/IVM-NLC could serve as a promising nanovector for bone-homing, active-targeted leukemia therapy.

Functionally graded hydrogels with opposing biochemical cues for osteochondral tissue engineering

Osteochondral tissue (OC) repair remains a significant challenge in the field of musculoskeletal tissue engineering. OC tissue displays a gradient structure characterized by variations in both cell types and extracellular matrix components, from cartilage to the subchondral bone. These functional gradients observed in the native tissue have been replicated to engineer OC tissuein vitro. While diverse fabrication methods have been employed to create these microenvironments, emulating the natural gradients and effective regeneration of the tissue continues to present a significant challenge. In this study, we present the design and development of CMC-silk interpenetrating (IPN) hydrogel with opposing dual biochemical gradients similar to native tissue with the aim to regenerate the complete OC unit. The gradients of biochemical cues were generated using an in-house-built extrusion system. Firstly, we fabricated a hydrogel that exhibits a smooth transition of sulfated carboxymethyl cellulose (sCMC) and TGF-β1 (SCT gradient hydrogel) from the upper to the lower region of the IPN hydrogel to regenerate the cartilage layer. Secondly, a hydrogel with a hydroxyapatite (HAp) gradient (HAp gradient hydrogel) from the lower to the upper region was fabricated to facilitate the regeneration of the subchondral bone layer. Subsequently, we developed a dual biochemical gradient hydrogel with a smooth transition of sCMC + TGF-β1 and HAp gradients in opposing directions, along with a blend of both biochemical cues in the middle. The results showed that the dual biochemical gradient hydrogels with biochemical cues corresponding to the three zones (i.e. cartilage, interface and bone) of the OC tissue led to differentiation of bone-marrow-derived mesenchymal stem cells to zone-specific lineages, thereby demonstrating their efficacy in directing the fate of progenitor cells. In summary, our study provided a simple and innovative method for incorporating gradients of biochemical cues into hydrogels. The gradients of biochemical cues spatially guided the differentiation of stem cells and facilitated tissue growth, which would eventually lead to the regeneration of the entire OC tissue with a smooth transition from cartilage (soft) to bone (hard) tissues. This promising approach is translatable and has the potential to generate numerous biochemical and biophysical gradients for regeneration of other interface tissues, such as tendon-to-muscle and ligament-to-bone.

Advances in guided bone regeneration membranes: a comprehensive review of materials and techniques

Guided tissue/bone regeneration (GTR/GBR) is a widely used technique in dentistry to facilitate the regeneration of damaged bone and tissue, which involves guiding materials that eventually degrade, allowing newly created tissue to take its place. This comprehensive review the evolution of biomaterials for guided bone regeneration that showcases a progressive shift from non-resorbable to highly biocompatible and bioactive materials, allowing for more effective and predictable bone regeneration. The evolution of biomaterials for guided bone regeneration GTR/GBR has marked a significant progression in regenerative dentistry and maxillofacial surgery. Biomaterials used in GBR have evolved over time to enhance biocompatibility, bioactivity, and efficacy in promoting bone growth and integration. This review also probes into several promising fabrication techniques like electrospinning and latest 3D printing fabrication techniques, which have shown potential in enhancing tissue and bone regeneration processes. Further, the challenges and future direction of GTR/GBR are explored and discussed.

Lysophosphatidic Acid/Polydopamine-Modified nHA Composite Scaffolds for Enhanced Osteogenesis via Upregulating the Wnt/Beta-Catenin Pathway

Guided bone regeneration (GBR) technology has been widely used for the regeneration of periodontal bone defects. However, the limited mechanical properties and bone regeneration potential of the currently available GBR membranes often limit their repair effectiveness. In this paper, serum-derived growth factor lysophosphatidic acid (LPA) nanoparticles and dopamine-decorative nanohydroxyapatite (pDA/nHA) particles were double-loaded into polylactic-glycolic acid/polycaprolactone (PLGA/PCL) scaffolds as an organic/inorganic biphase delivery system, namely, PP-pDA/nHA-LPA scaffolds. Physicochemical properties and osteogenic ability in vitro and in vivo were performed. Scanning electron microscopy and mechanical tests showed that the PP-pDA/nHA-LPA scaffolds had a 3D bionic scaffold structure with improved mechanical properties. In vitro cell experiments demonstrated that the PP-pDA/nHA-LPA scaffolds could significantly enhance the attachment, proliferation, osteogenic differentiation, and mineralization of MC3T3-E1 cells. In vivo, the PP-pDA/nHA-LPA scaffolds exhibited great cytocompatibility and cell recruitment ability in 2- and 4-week subcutaneous implantation experiments and significantly promoted bone regeneration in the periodontal defect scaffold implantation experiment. Moreover, LPA-loaded scaffolds were confirmed to enhance osteogenic activities by upregulating the expression of β-catenin and further activating the Wnt/β-catenin pathway. These results demonstrate that the biphase PP-pDA/nHA-LPA delivery system is a promising material for the GBR.

Incorporating mesoporous SiO2-HA particles into chitosan/hydroxyapatite scaffolds: A comprehensive evaluation of bioactivity and biocompatibility

In this work, composite scaffolds with various composition ratios of chitosan (CS), hydroxyapatite (HA), and mesoporous SiO2 particles co-synthesized with hydroxyapatite (SiO2-HA) were fabricated via the freeze-drying method for bone tissue engineering applications. Morphological studies showed that adding mesoporous particles resulted in a structure with a more uniformly porous geometry, subsequently leading to reduced biodegradation rates and water absorption in the scaffolds. The bioactivity results showed the introduction of mesoporous particles notably enhanced the coverage of the scaffold surface with apatite films. Moreover, biocompatibility assessments using sarcoma osteogenic cell line (SAOS-2) highlighted mesoporous particles' positive impact on cell adhesion and growth. The fluorescence images showed spindle-shaped cells with a greater number and normal cell nuclei for the scaffolds containing mesoporous SiO2-HA particles. The MTT cytotoxicity results indicated that the scaffolds containing mesoporous particles showed approximately 25 % higher cell survival more than single chitosan-based ones. What is more, the mesoporous-containing scaffolds occurred to have the best alkaline phosphatase test (ALP) activity among all scaffolds. It is important to add that CS/HA/mesoporous SiO2-HA scaffolds including SAOS-2 cells showed no sign of either early or late apoptosis. These findings affirm the potential of CS/HA/mesoporous SiO2-HA scaffolds as promising implants for bone tissue engineering.

Doxycycline-Loaded Calcium Phosphate Nanoparticles with a Pectin Coat Can Ameliorate Lipopolysaccharide-Induced Neuroinflammation Via Enhancing AMPK

Neuroinflammation occurs in response to different injurious triggers to limit their hazardous effects. However, failure to stop this process can end in multiple neurological diseases. Doxycycline (DX) is a tetracycline, with potential antioxidant and anti-inflammatory properties. The current study tested the effects of free DX, DX-loaded calcium phosphate (DX@CaP), and pectin-coated DX@CaP (Pec/DX@CaP) nanoparticles on the lipopolysaccharide (LPS)-induced neuroinflammation in mice and to identify the role of adenosine monophosphate-activated protein kinase (AMPK) in this effect. The present study was conducted on 48 mice, divided into 6 groups, eight mice each. Group 1 (normal control), Group 2 (blank nanoparticles-treated), Group 3 (LPS (untreated)), Groups 4, 5, and 6 received LPS, then Group 4 received free DX, Group 5 received DX-loaded calcium phosphate nanoparticles (DX@CaP), and Group 6 received DX-loaded calcium phosphate nanoparticles with a pectin coat (Pec/DX@CaP). At the end of the experimentation period, behavioral tests were carried out. Then, mice were sacrificed, and brain tissue was extracted and used for histological examination, and assessment of interleukin-6 positive cells in different brain areas, in addition to biochemical measurement of SOD activity, TLR-4, AMPK and Nrf2. LPS can induce prominent neuroinflammation. Treatment with (Pec/DX@CaP) can reverse most behavioral, histopathological, and biochemical changes caused by LPS. The findings of the current study suggest that (Pec/DX@CaP) exerts a significant reverse of LPS-induced neuroinflammation by enhancing SOD activity, AMPK, and Nrf2 expression, in addition to suppression of TLR-4.

Study on the poly(methyl methacrylate-acrylic acid)/calcium phosphate cement composite bound by chelation with enhanced water absorption and biomechanical properties

Polymethylmethacrylate (PMMA) bone cement has been widely used as a critical material for fixing prostheses and filling bone defects. The shrinkage of PMMA bone cement was addressed by the additives, however, the uneven integral water absorption and expansion performance as well as the deteriorated mechanical properties of the modified bone cement after immersion in phosphate buffered saline (PBS) and simulation body fluid (SBF) affected the long-term stability after implantation. Calcium phosphate cement (CPC) is a biomaterial with promising applications in orthopedics, whose hydration reaction provides an important driving force for the transfer of water. Besides, the mechanical properties of CPC can be enhanced with the curing process. In this study, CPC was utilized to modify the poly(methyl methacrylate-acrylic acid) [P(MMA-AA)] bone cement. The results demonstrated the successful construction of interconnected CPC water delivery networks in the P(MMA-AA)/CPC composite, the water absorption ratio and expansion ratio of the composite were up to 131.18 ± 9.14% and 168.19 ± 5.44%, respectively. Meanwhile, the transformation of CPC water delivery networks into rigid mechanical support networks as well as the chelation interaction between organic-inorganic enhanced the mechanical properties of the composite after immersion, the compressive strength after immersion reached 62.97 ± 0.97 MPa, which was 27.65% higher than that before immersion. The degradation ratio of the composite was up to 13.76 ± 0.23% after 9 days of immersion, which was 16.4% higher than that of CPC. Furthermore, composites exhibited superior biocompatibility as the release of Ca2+. Therefore, P(MMA-AA)/CPC composite serves as a promising medical filling material for clinical use.

A new composite fabricated from hydroxyapatite, gelatin-MgO microparticles, and compatibilized poly(butylene succinate) with osteogenic functionality

In this study, thermally processed recycled fish teeth (FT) and fish scales, magnesium oxide (MgO), and biobased polyesters were fabricated into new bioactive and environmentally friendly composites. The magnesium oxide was encapsulated into laboratory-made fish scale-derived gelatin to form gelatin-MgO microparticles. Hydroxyapatite (HA) and gelatin were obtained by heat-treating FTs and fish scales, respectively. Compatibilized poly(butylene succinate) (CPBS), i.e., poly(butylene succinate) (PBS) to which had been added acrylic acid-grafted PBS (PBS-g-AA) compatibilizer, was combined with HA/gelatin-MgO (GHA) to form CPBS/GHA composites. The structure and tensile properties of the composites were investigated. The CPBS/GHA composites improved the adhesion and proliferation of osteoblast cells. Osteoblast growth, osteoclast growth inhibition, and the antibacterial effect of CPBS/GHA composites were primarily due to the slow release of magnesium ions into the environment from the gelatin-MgO microparticles. Higher levels of calcium and phosphorus species were observed for various PBS/HA and CPBS/GHA composites immersed in simulated body fluid. Mineralization measurements indicated that calcium and phosphate ions precipitated in osteoblasts placed on PBS/HA and CPBS/GHA composites. The study successfully developed a new composite material containing 5 wt% gelatin/MgO (phr), CPBS/HA 10 wt% and 1.0 % gelatin/MgO (an optimum formula of MgO). This composite exhibited superior tensile strength, antibacterial effect, osteoclast growth enhancement, and osteoclast growth reduction. These results suggest that the composites may facilitate the formation of new bone formation in vivo. The CPBS/GHA composites displayed good bone tissue repair ability in engineering applications.

From materials to clinical use: advances in 3D-printed scaffolds for cartilage tissue engineering

Osteoarthritis caused by articular cartilage defects is a particularly common orthopedic disease that can involve the entire joint, causing great pain to its sufferers. A global patient population of approximately 250 million people has an increasing demand for new therapies with excellent results, and tissue engineering scaffolds have been proposed as a potential strategy for the repair and reconstruction of cartilage defects. The precise control and high flexibility of 3D printing provide a platform for subversive innovation. In this perspective, cartilage tissue engineering (CTE) scaffolds manufactured using different biomaterials are summarized from the perspective of 3D printing strategies, the bionic structure strategies and special functional designs are classified and discussed, and the advantages and limitations of these CTE scaffold preparation strategies are analyzed in detail. Finally, the application prospect and challenges of 3D printed CTE scaffolds are discussed, providing enlightening insights for their current research.

Investigations into the effects of scaffold microstructure on slow-release system with bioactive factors for bone repair

In recent years, bone tissue engineering (BTE) has played an essential role in the repair of bone tissue defects. Although bioactive factors as one component of BTE have great potential to effectively promote cell differentiation and bone regeneration, they are usually not used alone due to their short effective half-lives, high concentrations, etc. The release rate of bioactive factors could be controlled by loading them into scaffolds, and the scaffold microstructure has been shown to significantly influence release rates of bioactive factors. Therefore, this review attempted to investigate how the scaffold microstructure affected the release rate of bioactive factors, in which the variables included pore size, pore shape and porosity. The loading nature and the releasing mechanism of bioactive factors were also summarized. The main conclusions were achieved as follows: i) The pore shapes in the scaffold may have had no apparent effect on the release of bioactive factors but significantly affected mechanical properties of the scaffolds; ii) The pore size of about 400 μm in the scaffold may be more conducive to controlling the release of bioactive factors to promote bone formation; iii) The porosity of scaffolds may be positively correlated with the release rate, and the porosity of 70%-80% may be better to control the release rate. This review indicates that a slow-release system with proper scaffold microstructure control could be a tremendous inspiration for developing new treatment strategies for bone disease. It is anticipated to eventually be developed into clinical applications to tackle treatment-related issues effectively.

Biodegradable Biopolymeric Nanoparticles for Biomedical Applications-Challenges and Future Outlook

Biopolymers are polymers obtained from either renewable or non-renewable sources and are the most suitable candidate for tailor-made nanoparticles owing to their biocompatibility, biodegradability, low toxicity and immunogenicity. Biopolymeric nanoparticles (BPn) can be classified as natural (polysaccharide and protein based) and synthetic on the basis of their origin. They have been gaining wide interest in biomedical applications such as tissue engineering, drug delivery, imaging and cancer therapy. BPn can be synthesized by various fabrication strategies such as emulsification, ionic gelation, nanoprecipitation, electrospray drying and so on. The main aim of the review is to understand the use of nanoparticles obtained from biodegradable biopolymers for various biomedical applications. There are very few reviews highlighting biopolymeric nanoparticles employed for medical applications; this review is an attempt to explore the possibilities of using these materials for various biomedical applications. This review highlights protein based (albumin, gelatin, collagen, silk fibroin); polysaccharide based (chitosan, starch, alginate, dextran) and synthetic (Poly lactic acid, Poly vinyl alcohol, Poly caprolactone) BPn that has recently been used in many applications. The fabrication strategies of different BPn are also being highlighted. The future perspective and the challenges faced in employing biopolymeric nanoparticles are also reviewed.

Preparation and Characterization of Biomimetic Functional Scaffold with Gradient Structure for Osteochondral Defect Repair

Osteochondral (OC) defects cannot adequately repair themselves due to their sophisticated layered structure and lack of blood supply in cartilage. Although therapeutic interventions are reaching an advanced stage, current clinical therapies to repair defects are in their infancy. Among the possible therapies, OC tissue engineering has shown considerable promise, and multiple approaches utilizing scaffolds, cells, and bioactive factors have been pursued. The most recent trend in OC tissue engineering has been to design gradient scaffolds using different materials and construction strategies (such as bi-layered, multi-layered, and continuous gradient structures) to mimic the physiological and mechanical properties of OC tissues while further enabling OC repair. This review focuses specifically on design and construction strategies for gradient scaffolds and their role in the successful engineering of OC tissues. The current dilemmas in the field of OC defect repair and the efforts of tissue engineering to address these challenges were reviewed. In addition, the advantages and limitations of the typical fabrication techniques for gradient scaffolds were discussed, with examples of recent studies summarizing the future prospects for integrated gradient scaffold construction. This updated and enlightening review could provide insights into our current understanding of gradient scaffolds in OC tissue engineering.

Integrated gradient tissue-engineered osteochondral scaffolds: Challenges, current efforts and future perspectives

The osteochondral defect repair has been most extensively studied due to the rising demand for new therapies to diseases such as osteoarthritis. Tissue engineering has been proposed as a promising strategy to meet the demand of simultaneous regeneration of both cartilage and subchondral bone by constructing integrated gradient tissue-engineered osteochondral scaffold (IGTEOS). This review brought forward the main challenges of establishing a satisfactory IGTEOS from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue, and the limitations of obtaining the desired and required scaffold. Then, we comprehensively discussed and summarized the current tissue-engineered efforts to resolve the above challenges, including architecture strategies, fabrication techniques and in vitro/in vivo evaluation methods of the IGTEOS. Especially, we highlighted the advantages and limitations of various fabrication techniques of IGTEOS, and common cases of IGTEOS application. Finally, based on the above challenges and current research progress, we analyzed in details the future perspectives of tissue-engineered osteochondral construct, so as to achieve the perfect reconstruction of the cartilaginous and osseous layers of osteochondral tissue simultaneously. This comprehensive and instructive review could provide deep insights into our current understanding of IGTEOS.

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Providing main challenges to establish integrated gradient osteochondral scaffold.

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Discussing the current tissue-engineered efforts to resolve the above challenges.

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Highlighting construct techniques, and evaluation index and methods of IGTEOS.

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Discussing the future perspectives to achieve perfect osteochondral reconstruction.

CTAB enabled microwave-hydrothermal assisted mesoporous Zn-doped hydroxyapatite nanorods synthesis using bio-waste Nodipecten nodosus scallop for biomedical implant applications

In biomedical exploration, the predominant characteristic is synthesizing and fabricating multifunctional nanostructure with intensified biocompatibility and excellent antibacterial applications to avoid post-surgical implant failure. The objective of the current study is to examine ideal mesoporous zinc-doped hydroxyapatite (HAp) for future use in the field of biomedical research. In the present investigation, we synthesized mesoporous Zn-doped HAp nanorods with varied mole concentrations using a profound microwave hydrothermal method utilizing bio-waste Nodipecten nodosus scallop as a calcium source and CTAB as an organic modifier. Bio-waste Nodipecten nodosus scallop is a widely available cheap calcium precursor which is converted into pure and zinc-doped hydroxyapatite nanorods with the help of the microwave hydrothermal method. Different analytical techniques like spectroscopy and electron microscopy were employed to evaluate and precisely characterize the structural and morphological characteristics in synthesized pure and mesoporous Zn-doped HAp nanorods. CTAB and microwave hydrothermal methods successfully create mesoporous Zn-doped hydroxyapatite nanorods with different sizes and morphology. Mesoporous Zinc-doped HAp nanorods show excellent antibacterial activity against Klebsiella pneumoniae (MTCC 7407) and Bacillus subtilis (MTCC 1133), compared to other nanorods. ZnHAp-3 shows notable excellent results of antibacterial effect towards K. pneumoniae and B. subtilis, by exhibiting 12.36 ± 0.12 and 13.12 ± 0.16 mm zone of inhibition. Furthermore, ZnHAp-1 shows the lower zone of inhibition, while the ZnHAp-3 sample shows the highest zone of inhibition. A foremost study performed was toxicity assays to validate safe attributes of mesoporous zinc-doped HAp intensified with the proliferation function of the zebrafish model. The results reveal the non-toxic behavior of pure and mesoporous zinc-doped HAp samples. Thus, our studies provide evidence for the synthesis technique for the mesoporous zinc-doped HAp nanorods using a novel CTAB-enabled microwave hydrothermal method utilizing bio-waste Nodipecten nodosus scallop as a calcium source will be alternative affordable biocidal antibacterial materials for controlling post-surgical implant failures.

Evaluation of 'surgery-friendly' bone scaffold characteristics: 3D printed ductile BG/PCL scaffold with high inorganic content to repair critical bone defects

The repair of irregular and complex critical bone defects remains a challenge in clinical practice. The application of 3D-printed bioceramics particle/polymer composite scaffolds in bone tissue engineering has been widely studied. At present, the inorganic particle content of the composite scaffolds is generally low, resulting in poor osteogenic activity. However, scaffold with high inorganic content are highly brittle, difficult to operate during surgery, and cannot be in close contact with surrounding bones. Therefore, it is of great significance to design a 'surgery-friendly' scaffold with high bioceramic content and good ductility. In this study, we used the solvent method to add high concentration (wt% 70%) bioglass (BG) into polycaprolactone (PCL), and polyethylene glycol was used as plasticizer to prepare 70% BG/PCL composite scaffolds with high ductility using 3D printing technology.In vitroexperiments showed that the scaffold had good mechanical properties: easy extension, easy folding and strong compressive resistance. It also showed good performance in biocompatibility and osteogenic activity. It was further observed that compared with pure BG or PCL implantation, the scaffold with higher BG content could have more new bone tissue appeared after 12 weeks. All these results indicate that 3D-printed 70% BG/PCL scaffolds have great potential for personalized repair of bone defects.

Cranioplasty Using Three-Dimensional–Printed Polycaprolactone Implant and Free Latissimus Dorsi Musculocutaneous Flap in a Patient with Repeated Wound Problem following Titanium Cranioplasty

Titanium mesh is an alloplastic material widely used for the reconstruction of moderate-to-large skull defects. Repeated wound problems or infection following these reconstructions inevitably lead to the replacement of the cranioplasty material. Among the various alloplastic materials, polycaprolactone implants are usually used for the coverage of small defects such as burr holes. 1 Herein, we present a case of a large cranial defect successfully reconstructed with three-dimensional-printed polycaprolactone implant and a free latissimus dorsi musculocutaneous flap. Until 1-year follow-up, the patient showed a favorable esthetic outcome with no complications or wound relapse.

Hydroxyapatite-Tethered Peptide Hydrogel Promotes Osteogenesis

Hydroxyapatite (HAp) as natural bone composition is highly osteoinductive. To harvest its osteoinductivity in bone regenerative engineering, the HAp-supporting hydrogel is urgently needed to minimize inhomogeneous aggregation of HAp. Here, we developed a HAp-stabilizing hydrogel based on peptide self-assembly. FmocFFRR was efficient for HAp-capping due to arginine-phosphate interaction. Tethering FmocFFRR on the HAp surface facilitated self-assembly to form FmocFFRR/HAp hybrid hydrogel, enabling stable dispersion of HAp in it. The molecular interactions between FmocFFRR and HAp particles were studied using microscopic and spectral characterizations. FmocFFRR/HAp hydrogel exhibited more enhanced mechanical properties than FmocFFRR. The biocompatibility of FmocFFRR/HAp hydrogel was verified using an ATP assay and live-dead staining assay. More importantly, FmocFFRR/HAp hydrogel not only enabled cell attachment on its surface, but also supported 3D cell culturing inside the hydrogel. Further, 3D culturing of MC3T3-E1 preosteoblasts inside FmocFFRR/HAp hydrogel significantly enhanced the expressions of osteogenesis markers, including alkaline phosphate (ALP), type-I collagen (COL1), and osteocalcin (OCN), demonstrating the promoting effect of osteoblast differentiation. These findings inspire its potential application in bone regenerative engineering.

Biomaterials for Tissue Engineering Applications and Current Updates in the Field: A Comprehensive Review

Tissue engineering has emerged as an interesting field nowadays; it focuses on accelerating the auto-healing mechanism of tissues rather than organ transplantation. It involves implanting an In Vitro cultured initiative tissue or a scaffold loaded with tissue regenerating ingredients at the damaged area. Both techniques are based on the use of biodegradable, biocompatible polymers as scaffolding materials which are either derived from natural (e.g. alginates, celluloses, and zein) or synthetic sources (e.g. PLGA, PCL, and PLA). This review discusses in detail the recent applications of different biomaterials in tissue engineering highlighting the targeted tissues besides the in vitro and in vivo key findings. As well, smart biomaterials (e.g. chitosan) are fascinating candidates in the field as they are capable of elucidating a chemical or physical transformation as response to external stimuli (e.g. temperature, pH, magnetic or electric fields). Recent trends in tissue engineering are summarized in this review highlighting the use of stem cells, 3D printing techniques, and the most recent 4D printing approach which relies on the use of smart biomaterials to produce a dynamic scaffold resembling the natural tissue. Furthermore, the application of advanced tissue engineering techniques provides hope for the researchers to recognize COVID-19/host interaction, also, it presents a promising solution to rejuvenate the destroyed lung tissues.

Evaluation of the Anti-Cancer Potential of Rosa damascena Mill. Callus Extracts against the Human Colorectal Adenocarcinoma Cell Line

Chemotherapy is an aggressive form of chemical drug therapy aiming to destroy cancer cells. Adjuvant therapy may reduce hazards of chemotherapy and help in destroying these cells when obtained from natural products, such as medical plants. In this study, the potential therapeutic effect of Rosa damascena callus crude extract produced in vitamin-enhanced media is investigated on colorectal cancer cell line Caco-2. Two elicitors, i.e., L-ascorbic acid and citric acid at a concentration of 0.5 g/L were added to the callus induction medium. Callus extraction and the GC–MS analysis of methanolic crude extracts were also determined. Cytotoxicity, clonogenicity, proliferation and migration of Caco-2 colorectal cancer cells were investigated using MTT cytotoxicity, colony-forming, Ki-67 flow cytometry proliferation and Migration Scratch assays, respectively. Our results indicated that L-ascorbic acid treatment enhanced callus growth parameters and improved secondary metabolite contents. It showed the least IC50 value of 137 ug/mL compared to 237 ug/mL and 180 ug/mL in the citric acid-treated and control group. We can conclude that R. damascena callus elicited by L-ascorbic acid improved growth and secondary metabolite contents as well as having an efficient antiproliferative, anti-clonogenic and anti-migratory effect on Caco-2 cancer cells, thus, can be used as an adjuvant anti-cancer therapy.

Improved oral nutraceutical-based intervention for the management of obesity: pterostilbene-loaded chitosan nanoparticles

Aim: To formulate and assess the oral anti-obesity effect of polymeric-based pterostilbene (PS)-loaded nanoparticles. Methods: Pterostilbene-hydroxypropyl β-cyclodextrin inclusion complex loaded in chitosan nanoparticles (PS/HPβCD-NPs) were prepared and characterized in vitro. Cytotoxicity, pharmacokinetics and anti-obesity effects were assessed on Caco-2 cell line and high-fat-diet-induced obesity rat model, respectively. In vivo assessment included histological examination, protein and gene expression of obesity biomarkers in adipose tissues. Results: Safe PS/HPβCD-NPs were successfully prepared with improved bioavailability compared with free PS. PS/HPβCD-NPs showed an improved anti-obesity effect, as supported by histological examination, lipid profile, UCP1 gene expression and protein expression of SIRT1, COX2, IL-6 and leptin. Conclusion: Orally administered PS nanoparticles represent a new and promising anti-obesity strategy owing to the sustainable weight loss and minimal side effects; this may be of great socio-economic impact.

Translating Material Science into Bone Regenerative Medicine Applications: State-of-The Art Methods and Protocols

In the last 20 years, bone regenerative research has experienced exponential growth thanks to the discovery of new nanomaterials and improved manufacturing technologies that have emerged in the biomedical field. This revolution demands standardization of methods employed for biomaterials characterization in order to achieve comparable, interoperable, and reproducible results. The exploited methods for characterization span from biophysics and biochemical techniques, including microscopy and spectroscopy, functional assays for biological properties, and molecular profiling. This review aims to provide scholars with a rapid handbook collecting multidisciplinary methods for bone substitute R&D and validation, getting sources from an up-to-date and comprehensive examination of the scientific landscape.

Reshapable Osteogenic Biomaterials Combining Flexible Melt Electrowritten Organic Fibers with Inorganic Bioceramics

Ever-growing various applications, especially for tissue regeneration, cause a pressing need for novel methods to functionalize melt electrowritten (MEW) microfibrous scaffolds with unique nanomaterials. Here, two novel strategies are proposed to modify MEW polycaprolactone (PCL) grids with ZnO nanoparticles (ZP) or ZnO nanoflakes (ZF) to enhance osteogenic differentiation. The calcium mineralization levels of MC3T3 osteoblasts cultured on PCL/ZP 0.1 scaffolds are ∼3.91-fold higher than those cultured on nonmodified PCL scaffolds, respectively. Due to the nanotopography mimicking bone anatomy, the PCL/ZF scaffolds (∼2.60 times higher in ALP activity compared to PCL/ZP 1 and ∼2.17 times higher in mineralization compared to PCL/ZP 0.1) achieved superior results. Moreover, the flexible feature inherited from PCL grids makes it possible for them to act as a reshapable osteogenic bioscaffold. This study provides new strategies for synthesizing nanomaterials on microscale surfaces, opening up a new route for functionalizing MEW scaffolds to fulfill the growing demand of tissue engineering.

3D Printed Poly(𝜀-caprolactone)/Hydroxyapatite Scaffolds for Bone Tissue Engineering: A Comparative Study on a Composite Preparation by Melt Blending or Solvent Casting Techniques and the Influence of Bioceramic Content on Scaffold Properties

Bone tissue engineering has been developed in the past decades, with the engineering of bone substitutes on the vanguard of this regenerative approach. Polycaprolactone-based scaffolds are fairly applied for bone regeneration, and several composites have been incorporated so as to improve the scaffolds' mechanical properties and tissue in-growth. In this study, hydroxyapatite is incorporated on polycaprolactone-based scaffolds at two different proportions, 80:20 and 60:40. Scaffolds are produced with two different blending methods, solvent casting and melt blending. The prepared composites are 3D printed through an extrusion-based technique and further investigated with regard to their chemical, thermal, morphological, and mechanical characteristics. In vitro cytocompatibility and osteogenic differentiation was also assessed with human dental pulp stem/stromal cells. The results show the melt-blending-derived scaffolds to present more promising mechanical properties, along with the incorporation of hydroxyapatite. The latter is also related to an increase in osteogenic activity and promotion. Overall, this study suggests polycaprolactone/hydroxyapatite scaffolds to be promising candidates for bone tissue engineering, particularly when produced by the MB method.

PLA/Hydroxyapatite scaffolds exhibit in vitro immunological inertness and promote robust osteogenic differentiation of human mesenchymal stem cells without osteogenic stimuli

Bone defects stand out as one of the greatest challenges of reconstructive surgery. Fused deposition modelling (FDM) allows for the printing of 3D scaffolds tailored to the morphology and size of bone damage in a patient-specific and high-precision manner. However, FDM still suffers from the lack of materials capable of efficiently supporting osteogenesis. In this study, we developed 3D-printed porous scaffolds composed of polylactic acid/hydroxyapatite (PLA/HA) composites with high ceramic contents (above 20%, w/w) by FDM. The mechanical properties of the PLA/HA scaffolds were compatible with those of trabecular bone. In vitro degradation tests revealed that HA can neutralize the acidification effect caused by PLA degradation, while simultaneously releasing calcium and phosphate ions. Importantly, 3D-printed PLA/HA did not induce the upregulation of activation markers nor the expression of inflammatory cytokines in dendritic cells thus exhibiting no immune-stimulatory properties in vitro. Evaluations using human mesenchymal stem cells (MSC) showed that pure PLA scaffolds exerted an osteoconductive effect, whereas PLA/HA scaffolds efficiently induced osteogenic differentiation of MSC even in the absence of any classical osteogenic stimuli. Our findings indicate that 3D-printed PLA scaffolds loaded with high concentrations of HA are most suitable for future applications in bone tissue engineering.

Binding Peptide-Promoted Biofunctionalization of Graphene Paper with Hydroxyapatite for Stimulating Osteogenic Differentiation of Mesenchymal Stem Cells

Graphene paper (GP), a macroscopic self-supporting material, has exceptional flexibility and preserves the excellent physical and chemical properties of graphene nanomaterials. But its applications in regenerative medicine remain to be further explored. Here, we biologically functionalized GP with hydroxyapatite (HA) nanorods by the use of GP-binding peptides as an affinity linker. This strategy solved two daunting challenges for regenerative medicine applications of GP: the lack of good hydrophilicity for supporting cell growth and the difficulty in forming composites by binding with nanobiomaterials. Briefly, we first screened a high-affinity GP-binding peptide (TWWNPRLVYFDY) by the phage display technique. Then we chemically conjugated the GP-binding peptide to the synthetic HA nanorods. The GP-binding peptide on the resultant HA nanorods enabled them to be bound and assembled onto the GP substrate with high affinity, forming a GP-peptide-HA composite with significantly improved hydrophilicity of GP. The composite promoted the attachment and proliferation of mesenchymal stem cells (MSCs), demonstrating its outstanding biocompatibility. Due to the unique compositions of the composite, it was also found to induce osteogenic differentiation of MSCs in vitro in the absence of other inducers in the medium, by verifying the expression of the osteogenic markers including collagen-1, bone morphogenetic proteins 2, runx-related transcription factor 2, osteocalcin, and alkaline phosphatase. Our work suggests that the GP-binding peptide can be used to link inorganic nanoparticles onto GP to facilitate the biomedical applications of GP.

Nanotopography in directing osteogenic differentiation of mesenchymal stem cells: potency and future perspective

Severe bone injuries can result in disabilities and thus affect a person's quality of life. Mesenchymal stem cells (MSCs) can be an alternative for bone healing by growing them on nanopatterned substrates that provide mechanical signals for differentiation. This review aims to highlight the role of nanopatterns in directing or inducing MSC osteogenic differentiation, especially in bone tissue engineering. Nanopatterns can upregulate the expression of osteogenic markers, which indicates a faster differentiation process. Combined with growth factors, nanopatterns can further upregulate osteogenic markers, but with fewer growth factors needed, thereby reducing the risks and costs involved. Nanopatterns can be applied in scaffolds for tissue engineering for their lasting effects, even in vivo, thus having great potential for future bone treatment.

Stimuli-responsive Polymeric nanosystems for therapeutic applications

BACKGROUND

Recent past decades have reported emerging of polymeric nanoparticles as a promising technique for controlled and targeted drug delivery. As nanocarriers, they have high drug loading and delivery to the specific site or targeted cells with an advantage of no drug leakage within en route and unloading of a drug in a sustained fashion at the site. These stimuli-responsive systems are functionalized in dendrimers, metallic nanoparticles, polymeric nanoparticles, liposomal nanoparticles, quantum dots.

PURPOSE OF REVIEW

The authors reviewed the potential of smart stimuli-responsive carriers for therapeutic application and their behavior in external or internal stimuli like pH, temperature, redox, light, and magnet. These stimuli-responsive drug delivery systems behave differently in In vitro and In vivo drug release patterns. Stimuli-responsive nanosystems include both hydrophilic and hydrophobic systems. This review highlights the recent development of the physical properties and their application in specific drug delivery.

CONCLUSION

The stimuli (smart, intelligent, programmed) drug delivery systems provide site-specific drug delivery with potential therapy for cancer, neurodegenerative, lifestyle disorders. As development and innovation, the stimuli-responsive based nanocarriers are moving at a fast pace and huge demand for biocompatible and biodegradable responsive polymers for effective and safe delivery.

Comparison of the Morphological and Structural Characteristic of Bioresorbable and Biocompatible Hydroxyapatite-Loaded Biopolymer Composites

Calcium phosphate (CaP)-based ceramic-biopolymer composites can be regarded as innovative bioresorbable coatings for load-bearing implants that can promote the osseointegration process. The carbonated hydroxyapatite (cHAp) phase is the most suitable CaP form, since it has the highest similarity to the mineral phase in human bones. In this paper, we investigated the effect of wet chemical preparation parameters on the formation of different CaP phases and compared their morphological and structural characteristics. The results revealed that the shape and crystallinity of CaP particles were strongly dependent on the post-treatment methods, such as heat or alkaline treatment of as-precipitated powders. In the next step, the optimised cHAp particles have been embedded into two types of biopolymers, such as polyvinyl pyrrolidone (PVP) and cellulose acetate (CA). The pure polymer fibres and the cHAp-biopolymer composites were produced using a novel electrospinning technique. The SEM images showed the differences between the morphology and network of CA and PVP fibres as well as proved the successful attachment of cHAp particles. In both cases, the fibres were partially covered with cHAp clusters. The SEM measurements on samples after one week of immersion in PBS solution evidenced the biodegradability of the cHAp-biopolymer composites.

3D printed bioinspired scaffolds integrating doxycycline nanoparticles: Customizable implants for in vivo osteoregeneration

3D printing has revolutionized pharmaceutical research, with applications encompassing tissue regeneration and drug delivery. Adopting 3D printing for pharmaceutical drug delivery personalization via nanoparticle-reinforced hydrogel scaffolds promises great regenerative potential. Herein, we engineered novel core/shell, bio-inspired, drug-loaded polymeric hydrogel scaffolds for pharmaceutically personalized drug delivery and superior osteoregeneration. Scaffolds were developed using biopolymeric blends of gelatin, polyvinyl alcohol and hyaluronic acid and integrated with composite doxycycline/hydroxyapatite/polycaprolactone nanoparticles (DX/HAp/PCL) innovatively via 3D printing. The developed scaffolds were optimized for swelling pattern and in-vitro drug release through tailoring the biphasic microstructure and wet/dry state to attain various pharmaceutical personalization platforms. Freeze-dried scaffolds with nanoparticles reinforcing the core phase (DX/HAp/PCL-LCS-FD) demonstrated favorably controlled swelling, preserved structural integrity and controlled drug release over 28 days. DX/HAp/PCL-LCS-FD featured double-ranged pore size (90.4 ± 3.9 and 196.6 ± 38.8 µm for shell and core phases, respectively), interconnected porosity and superior mechanical stiffness (74.5 ± 6.8 kPa) for osteogenic functionality. Cell spreading analysis, computed tomography and histomorphometry in a rabbit tibial model confirmed osteoconduction, bioresorption, immune tolerance and bone regenerative potential of the original scaffolds, affording complete defect healing with bone tissue. Our findings suggest that the developed platforms promise prominent local drug delivery and bone regeneration.

Pharmaceutical electrospinning and 3D printing scaffold design for bone regeneration

Bone regenerative engineering provides a great platform for bone tissue regeneration covering cells, growth factors and other dynamic forces for fabricating scaffolds. Diversified biomaterials and their fabrication methods have emerged for fabricating patient specific bioactive scaffolds with controlled microstructures for bridging complex bone defects. The goal of this review is to summarize the points of scaffold design as well as applications for bone regeneration based on both electrospinning and 3D bioprinting. It first briefly introduces biological characteristics of bone regeneration and summarizes the applications of different types of material and the considerations for bone regeneration including polymers, ceramics, metals and composites. We then discuss electrospinning nanofibrous scaffold applied for the bone regenerative engineering with various properties, components and structures. Meanwhile, diverse design in the 3D bioprinting scaffolds for osteogenesis especially in the role of drug and bioactive factors delivery are assembled. Finally, we discuss challenges and future prospects in the development of electrospinning and 3D bioprinting for osteogenesis and prominent strategies and directions in future.

Engineering 3D-printed core-shell hydrogel scaffolds reinforced with hybrid hydroxyapatite/polycaprolactone nanoparticles for in vivo bone regeneration

The versatility of 3D printing has rendered it an indispensable tool for the fabrication of composite hydrogel scaffolds, offering bone biomimetic features through inorganic and biopolymeric components as promising platforms for osteoregeneration. In this work, extrusion-based 3D printing was employed for the realization of osteoconductive composite biopolymer-based hydrogel scaffolds reinforced with hybrid bioactive hydroxyapatite/polycaprolactone nanoparticles (HAp/PCL NPs) for osteoregeneration. The printing technique was optimized for ink printability and viscosity and crosslinking parameters, where a biopolymeric blend of gelatin, polyvinyl alcohol and hyaluronic acid was developed as innovative plain polymeric ink (PPI). Scaffolds were fabricated by 3D printing adopting a biphasic core/shell geometry, where the core phase of the scaffolds was reinforced with HAp/PCL NPs; the scaffolds were then freeze-dried. Novel composite freeze-dried, loaded-core scaffolds, HAp/PCL NPs-LCS-FD exhibited controlled swelling and maintained structural integrity for 28 days. The developed HAp/PCL NPs-LCS-FD also demonstrated double-ranged pore size, interconnected porosity and efficient mechanical stiffness and strength, favorable for osteoconductive actions. Cell infiltration studies, computed tomography and histomorphometry demonstrated that HAp/PCL NPs-LCS-FD afforded osteoconduction, biodegradation, biocompatibility and bone healing in rabbit tibial model, acting as a template for new bone formation. Our findings suggest that HAp/PCL NPs-LCS-FD could offer prominent bone regeneration and could be involved in various bone defects.

Development, processing and characterization of Polycaprolactone/Nano-Hydroxyapatite/Chitin-Nano-Whisker nanocomposite filaments for additive manufacturing of bone tissue scaffolds

This paper focuses on utilizing the Fused Deposition Modeling (FDM) to manufacture Polycaprolactone/Nano-Hydroxyapatite/Chitin-Nano-Whisker nanocomposite scaffolds and their subsequent characterization for biomedical applications. FDM nanocomposite filaments were manufactured in multiple nanocomposite formulations of Polycaprolactone/Nano-Hydroxyapatite (nHA), Polycaprolactone/Chitin-Nano-Whisker (CNW), and Polycaprolactone/nHA/CNW using a green method. The FDM processing conditions were optimized using Taguchi orthogonal array method. The mechanical, biodegradation, and biocompatibility properties of the bone tissue scaffolds were assessed. A preosteoblast mouse bone cell line was used for cell proliferation and attachment assays. The results indicated that CNW content in the filaments slightly increases the mechanical properties of the 3D printed parts, and the nanocomposite with 3% CNW content exhibited significant improvement in the cell proliferation and attachment properties of the scaffolds. The nHA content considerably improved the mechanical properties of the scaffolds. The nHA and CNW nanofillers increased the biodegradation rate of PCL. In general, considering all types of responses, a green manufactured nanocomposite of PCL/nHA/CNW can significantly increase the biological and mechanical properties of the 3D printed products for bone tissue scaffolds.

Enzymatic Preparation and Characterization of Spherical Microparticles Composed of Artificial Lignin and TEMPO-Oxidized Cellulose Nanofiber

A one-pot and one-step enzymatic synthesis of submicron-order spherical microparticles composed of dehydrogenative polymers (DHPs) of coniferyl alcohol as a typical lignin precursor and TEMPO-oxidized cellulose nanofibers (TOCNFs) was investigated. Horseradish peroxidase enzymatically catalyzed the radical coupling of coniferyl alcohol in an aqueous suspension of TOCNFs, resulting in the formation of spherical microparticles with a diameter and sphericity index of approximately 0.8 μm and 0.95, respectively. The ζ-potential of TOCNF-functionalized DHP microspheres was about -40 mV, indicating that the colloidal systems had good stability. Nanofibrous components were clearly observed on the microparticle surface by scanning electron microscopy, while some TOCNFs were confirmed to be inside the microparticles by confocal laser scanning microscopy with Calcofluor white staining. As both cellulose and lignin are natural polymers known to biodegrade, even in the sea, these woody TOCNF-DHP microparticle nanocomposites were expected to be promising alternatives to fossil resource-derived microbeads in cosmetic applications.

Additive Manufacturing of Porous Ti6Al4V Alloy: Geometry Analysis and Mechanical Properties Testing

This work is devoted to the research of porous titanium alloy structures suitable for use in biomedical applications. Mechanical properties were examined on six series of samples with different structures and porosity via static compressive test to identify the type of structure suitable for elimination of the “stress shielding” effect. In addition, high porosity is desirable due to the overgrowth of bone tissue into the internal structure of the implant. The samples were made of titanium alloy Ti6Al4V by using selective laser melting (SLM) additive manufacturing. The series of samples differ from each other in pore size (200, 400, and 600 µm) and porous structure topology (cubic or trabecular). The actual weight of all samples, which plays an important role in identifying other characteristics, was determined. Compressive tests were focused on the detection of maximum stress. The highest porosity and thus the lowest weight were achieved in the samples with a trabecular structure and 600 µm pore size. All tested samples reached optimal values of maximum stress and tensile strength. The most appropriate mechanical properties were observed for samples with a 200 µm pore diameter and cubic structure.

Biomaterial-Based Nanocomposite for Osteogenic Repurposing of Doxycycline

Background

Besides its antimicrobial action, doxycycline (DX) has lately been repurposed as a small-molecule drug for osteogenic purposes. However, osteogenic DX application is impeded by its dose-dependent cytotoxicity. Further, high-dose DX impairs cell differentiation and mineralization.

Purpose

Integrating DX into a biomaterial-based delivery system that can control its release would not only ameliorate its cytotoxic actions but also augment its osteogenic activity. In this work, we managed to engineer novel composite DX–hydroxyapatite–polycaprolactone nanoparticles (DX/HAp/PCL) to modify DX osteogenic potential.

Methods

Employing a 2³-factorial design, we first optimized HApN for surface-area attributes to maximize DX loading. Composite DX/HAp/PCL were then realized using a simple emulsification technique, characterized using various in vitro methods, and evaluated for in vitro osteogenesis.

Results

The developed HApN exhibited a favorable crystalline structure, Ca:P elemental ratio (1.67), mesoporous nature, and large surface area. DX/HAp/PCL achieved the highest reported entrapment efficiency (94.77%±1.23%) of DX in PCL-based particles. The developed composite system achieved controlled release of the water-soluble DX over 24 days. Moreover, the novel composite nanosystem managed to significantly ameliorate DX cytotoxicity on bone-marrow stem cells, as well as enhance its overall proliferation potential. Alkaline phosphatase and mineralization assays revealed superior osteodifferentiation potential of the composite system. Quantification of gene expression demonstrated that while DX solution was able to drive bone-marrow stem cells down the osteogenic lineage into immature osteoblasts after 10-day culture, the innovative composite system allowed maturation of osteodifferentiated cells. To the best of our knowledge, this is the first work to elaborate the impact of DX on the expression of osteogenic genes: RUNX2, OSP, and BSP. Further, the osteogenicity of a DX-loaded particulate-delivery system has not been previously investigated.

Conclusion

Our findings indicate that repurposing low-dose DX in complementary biomaterial-based nanosystems can offer a prominent osteogenic candidate for bone-regeneration purposes.