Hydroxyapatite nanorod and microsphere functionalized with bioactive lactoferrin as a new biomaterial for enhancement bone regeneration

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.

A review of the biological activities of lactoferrin: mechanisms and potential applications

Lactoferrin, a multifunctional iron-binding protein found in milk and other body fluids, possesses numerous biological activities. The functional activity of lactoferrin lies not only in its iron-binding capacity but also in the molecular mechanisms by which it can affect important chemical components in the host. However, the molecular mechanisms underlying these activities remain unelucidated. In this paper, we review the structure, properties, and contents of different lactoferrin milk sources. The different biological activities, namely antibacterial, antiviral, immunomodulatory, anti-inflammatory, bone regeneration, and improved metabolic disorder bioactivities, and the associated potential mechanisms of lactoferrin are summarized with the aim of providing a reference for the development of lactoferrin-related products.

Use of Biomaterials in 3D Printing as a Solution to Microbial Infections in Arthroplasty and Osseous Reconstruction

The incidence of microbial infections in orthopedic prosthetic surgeries is a perennial problem that increases morbidity and mortality, representing one of the major complications of such medical interventions. The emergence of novel technologies, especially 3D printing, represents a promising avenue of development for reducing the risk of such eventualities. There are already a host of biomaterials, suitable for 3D printing, that are being tested for antimicrobial properties when they are coated with bioactive compounds, such as antibiotics, or combined with hydrogels with antimicrobial and antioxidant properties, such as chitosan and metal nanoparticles, among others. The materials discussed in the context of this paper comprise beta-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP), hydroxyapatite, lithium disilicate glass, polyetheretherketone (PEEK), poly(propylene fumarate) (PPF), poly(trimethylene carbonate) (PTMC), and zirconia. While the recent research results are promising, further development is required to address the increasing antibiotic resistance exhibited by several common pathogens, the potential for fungal infections, and the potential toxicity of some metal nanoparticles. Other solutions, like the incorporation of phytochemicals, should also be explored. Incorporating artificial intelligence (AI) in the development of certain orthopedic implants and the potential use of AI against bacterial infections might represent viable solutions to these problems. Finally, there are some legal considerations associated with the use of biomaterials and the widespread use of 3D printing, which must be taken into account.

Nanoparticular and other carriers to deliver lactoferrin for antimicrobial, antibiofilm and bone-regenerating effects: a review

Bone and joint infections are a rare but serious problem worldwide. Lactoferrin’s antimicrobial and antibiofilm activity coupled with its bone-regenerating effects may make it suitable for improving bone and joint infection treatment. However, free lactoferrin (LF) has highly variable oral bioavailability in humans due to potential for degradation in the stomach and small intestine. It also has a short half-life in blood plasma. Therefore, encapsulating LF in nanocarriers may slow degradation in the gastrointestinal tract and enhance LF absorption, stability, permeability and oral bioavailability. This review will summarize the literature on the encapsulation of LF into liposomes, solid lipid nanoparticles, nanostructured lipid carriers, polymeric micro and nanoparticles and hydroxyapatite nanocrystals. The fabrication, characterization, advantages, disadvantages and applications of each system will be discussed and compared.

Frontiers of Hydroxyapatite Composites in Bionic Bone Tissue Engineering

Bone defects caused by various factors may cause morphological and functional disorders that can seriously affect patient's quality of life. Autologous bone grafting is morbid, involves numerous complications, and provides limited volume at donor site. Hence, tissue-engineered bone is a better alternative for repair of bone defects and for promoting a patient's functional recovery. Besides good biocompatibility, scaffolding materials represented by hydroxyapatite (HA) composites in tissue-engineered bone also have strong ability to guide bone regeneration. The development of manufacturing technology and advances in material science have made HA composite scaffolding more closely related to the composition and mechanical properties of natural bone. The surface morphology and pore diameter of the scaffold material are more important for cell proliferation, differentiation, and nutrient exchange. The degradation rate of the composite scaffold should match the rate of osteogenesis, and the loading of cells/cytokine is beneficial to promote the formation of new bone. In conclusion, there is no doubt that a breakthrough has been made in composition, mechanical properties, and degradation of HA composites. Biomimetic tissue-engineered bone based on vascularization and innervation show a promising future.

Functionalized Porous Hydroxyapatite Scaffolds for Tissue Engineering Applications: A Focused Review

Biomaterials have been widely used in tissue engineering applications at an increasing rate in recent years. The increased clinical demand for safe scaffolds, as well as the diversity and availability of biomaterials, has sparked rapid interest in fabricating diverse scaffolds to make significant progress in tissue engineering. Hydroxyapatite (HAP) has drawn substantial attention in recent years owing to its excellent physical, chemical, and biological properties and facile adaptable surface functionalization with other innumerable essential materials. This focused review spotlights a brief introduction on HAP, scope, a historical outline, basic structural features/properties, various synthetic strategies, and their scientific applications concentrating on functionalized HAP in the diverse area of tissue engineering fields such as bone, skin, periodontal, bone tissue fixation, cartilage, blood vessel, liver, tendon/ligament, and corneal are emphasized. Besides clinical translation aspects, the future challenges and prospects of HAP based biomaterials involved in tissue engineering are also discussed. Furthermore, it is expected that researchers may find this review expedient in gaining an overall understanding of the latest advancement of HAP based biomaterials.

Osteogenic effect of polymethyl methacrylate bone cement with surface modification of lactoferrin

Polymethyl methacrylate (PMMA) bone cement is a commonly used filling material in orthopedic surgery. Its good and stable performances make it the most widely used in all kinds of bone cement. With the advancement of the application and research of PMMA bone cement by surgeons, its disadvantages such as non-degradation and non-bioactivity are gradually exposed. In recent years, the biological functions of lactoferrin (LF) have been gradually explored, especially its role in promoting osteogenesis. In this study, LF was modified on the surface of solidified PMMA bone cement (LF/PMMA bone cement) by physical/chemical mixed modification and verified by cytological experiments in vitro. In vitro studies have implicated that PMMA bone cement modified with LF can improve the attachment, expansion, proliferation, extracellular matrix secretion and osteogenic differentiation of mouse preosteoblasts (MC3T3-E1) cells, indicating biocompatibility. This experiment provides a novel insight for improving the biological activity of PMMA bone cement and lays a foundation for broadening the clinical application of PMMA bone cement.

Lactoferrin as a regenerative agent: The old-new panacea?

Lactoferrin (Lf) possesses various biological properties and therapeutic potentials being a perspective anti-inflammatory, antibacterial, antiviral, antioxidant, antitumor, and immunomodulatory agent. A significant body of literature has also demonstrated that Lf modulates regenerative processes in different anatomical structures, such as bone, cartilage, skin, mucosa, cornea, tendon, vasculature, and adipose tissue. Hence, this review collected and analyzed the data on the regenerative effects of Lf, as well as paid specific attention to their molecular basis. Furthermore, tissue and condition-specific activities of different Lf types as well as problems of their delivery to the targeted organs were discussed. The authors strongly hope that this review will stimulate researchers to focus on the highlighted topics thus accelerating the progress of Lf's wider clinical application.

Hydroxyapatite-Bovine Serum Albumin-Paclitaxel Nanoparticles for Locoregional Treatment of Osteosarcoma

Osteosarcoma is the most primary type of bone tumor occurring in the pediatric and adolescent age groups. In order to obtain the most appropriate prognosis, both tumor recurrence inhibition and bone repair promotion are required. In this study, a ternary nanoscale biomaterial/antitumor drug complex including hydroxyapatite (HA), bovine serum albumin (BSA) and paclitaxel (PTX) is prepared for post-surgical cancer treatment of osteosarcoma in situ. The HA-BSA-PTX nanoparticles, about 55 nm in diameter with drug loading efficiency (32.17 wt%), have sustained release properties of PTX and calcium ions (Ca²⁺ ) and low cytotoxicity to human fetal osteoblastic (hFOB 1.19) cells in vitro. However, for osteosarcoma (143B) cells, the proliferation, migration, and invasion ability are significantly inhibited. The in situ osteosarcoma model studies demonstrate that HA-BSA-PTX nanoparticles have significant anticancer effects and can effectively inhibit tumor metastasis. Meanwhile, the detection of alkaline phosphatase activity, calcium deposition, and reverse transcription-polymerase chain reaction proves that the HA-BSA-PTX nanoparticles can promote the osteogenic differentiation. Therefore, the HA-BSA-PTX nanodrug delivery system combined with sustained drug release, antitumor, and osteogenesis effects is a promising agent for osteosarcoma adjuvant therapy.

Genistein Improves Bone Healing via Triggering Estrogen Receptor Alpha-Mediated Expressions of Osteogenesis-Associated Genes and Consequent Maturation of Osteoblasts

Osteoporosis-associated fractures may cause higher morbidity and mortality. Our previous study showed the effects of genistein, a phytoestrogen, on the induction of estrogen receptor alpha (ERα) gene expression and stimulation of osteoblast mineralization. In this study, rat calvarial osteoblasts and an animal bone defect model were used to investigate the effects of genistein on bone healing. Treatment with genistein caused a time-dependent increase in alkaline phosphatase (ALP) activity in rat osteoblasts. Levels of cytosolic and nuclear ERα significantly augmented following exposure to genistein. Subsequently, genistein elevated levels of ALP mRNA and protein in rat osteoblasts. Moreover, genistein induced other osteogenesis-associated osteocalcin and Runx2 mRNA and protein expressions. Knocking-down ERα using RNA interference concurrently inhibited genistein-induced Runx2, osteocalcin, and ALP mRNA expression. Attractively, administration of ICR mice suffering bone defects with genistein caused significant increases in the callus width, chondrocyte proliferation, and ALP synthesis. Results of microcomputed tomography revealed that administration of genistein increased trabecular bone numbers and improved the bone thickness and volume. This study showed that genistein can improve bone healing via triggering ERα-mediated osteogenesis-associated gene expressions and subsequent osteoblast maturation.

Lactoferrin Functionalized Biomaterials: Tools for Prevention of Implant-Associated Infections

Tissue engineering is one of the most important biotechnologies in the biomedical field. It requires the application of the principles of scientific engineering in order to design and build natural or synthetic biomaterials feasible for the maintenance of tissues and organs. Depending on the specific applications, the selection of the proper material remains a significant clinical concern. Implant-associated infection is one of the most severe complications in orthopedic implant surgeries. The treatment of these infections is difficult because the surface of the implant serves not only as a substrate for the formation of the biofilm, but also for the selection of multidrug-resistant bacterial strains. Therefore, a promising new approach for prevention of implant-related infection involves development of new implantable, non-antibiotic-based biomaterials. This review provides a brief overview of antimicrobial peptide-based biomaterials-especially those coated with lactoferrin.

Lactoferrin in Bone Tissue Regeneration

Among the multiple properties exhibited by lactoferrin (Lf), its involvement in bone regeneration processes is of great interest at the present time. A series of in vitro and in vivo studies have revealed the ability of Lf to promote survival, proliferation and differentiation of osteoblast cells and to inhibit bone resorption mediated by osteoclasts. Although the mechanism underlying the action of Lf in bone cells is still not fully elucidated, it has been shown that its mode of action leading to the survival of osteoblasts is complemented by its mitogenic effect. Activation of several signalling pathways and gene expression, in an LRPdependent or independent manner, has been identified. Unlike the effects on osteoblasts, the action on osteoclasts is different, with Lf leading to a total arrest of osteoclastogenesis. Due to the positive effect of Lf on osteoblasts, the potential use of Lf alone or in combination with different biologically active compounds in bone tissue regeneration and the treatment of bone diseases is of great interest. Since the bioavailability of Lf in vivo is poor, a nanotechnology- based strategy to improve the biological properties of Lf was developed. The investigated formulations include incorporation of Lf into collagen membranes, gelatin hydrogel, liposomes, loading onto nanofibers, porous microspheres, or coating onto silica/titan based implants. Lf has also been coupled with other biologically active compounds such as biomimetic hydroxyapatite, in order to improve the efficacy of biomaterials used in the regulation of bone homeostasis. This review aims to provide an up-to-date review of research on the involvement of Lf in bone growth and healing and on its use as a potential therapeutic factor in bone tissue regeneration.

Nbr1-regulated autophagy in Lactoferrin-induced osteoblastic differentiation

The molecular mechanism of autophagy in Lactoferrin (LF) induced osteoblast differentiation is not fully demonstrated. In this study, alkaline phosphatase (ALP) activity, alizarin red S staining and ELISA were used to study N-terminal propeptide of type I procollagen (PINP) expression. mRFP-GFP-LC3 adenoviruses, mono-dansylcadaverine (MDC) staining, scanning electron microscopy, and western blot analysis was employed to probe the LF induced autophagy. The interaction between autophagy receptor Neighbor of Brca1 gene (Nbr1) and pp38 was studied. 3-methyladenine (3-MA) and chloroquine (CQ) could inhibit the activity of ALP, PINP and the autophagy in LF group. LF treatment could up-regulate and down-regulate the expressions of pp38 and Nbr1with a dose-dependent manner, respectively. LF could inhibit the recognition of pp38 and Nbr1. In addition, LF can prompt Nbr1-medicated autophagy and prevent pp38 degradation by autophagy. LF can induce Nbr1-mediated autophagy and inhibit pp38 entering into autophagy flux in the physiological process of osteoblast differentiation.Abbreviations: CQ:chloroquine；LF: Lactoferrin; 3-MA: 3-methyladenine; ALP: Alkaline phosphatase; ANOVA: Analysis of variance; CCK-8: Cell Counting Kit-8; LC3: Microtubule-associated protein light chain3; MDC: Monodansylcadaverine; Nbr1: neighbor of Brca1 gene; PINP: N-terminal propeptide of type I procollagen; PVDF: Polychlorotrifluoroethylene; pp38: phosphorylation p38; RAPA: Rapamycin; SDS: sodium dodecyl sulfate.

Functionalized calcium orthophosphates (CaPO4) and their biomedical applications

Due to the chemical similarity to natural calcified tissues (bones and teeth) of mammals, calcium orthophosphates (abbreviated as CaPO₄) appear to be good biomaterials for creation of artificial bone grafts. However, CaPO₄ alone have some restrictions, which limit their biomedical applications. Various ways have been developed to improve the properties of CaPO₄ and their functionalization is one of them. Namely, since surfaces always form the interfaces between implanted grafts and surrounding tissues, the state of CaPO₄ surfaces plays a crucial role in the survival of bone grafts. Although the biomedically relevant CaPO₄ possess the required biocompatible properties, some of their properties could be better. For example, functionalization of CaPO₄ to enhance cell attachment and cell material interactions has been developed. In addition, to prepare stable formulations from nanodimensional CaPO₄ particles and prevent them from agglomerating, the surfaces of CaPO₄ particles are often functionalized by sorption of special chemicals. Furthermore, there are functionalizations in which CaPO₄ are exposed to various types of physical treatments. This review summarizes the available knowledge on CaPO₄ functionalizations and their biomedical applications.

Human Mesenchymal Stem Cell Response to Lactoferrin-based Composite Coatings

The potential of mesenchymal stem cells (MSCs) for implantology and cell-based therapy represents one of the major ongoing research subjects within the last decades. In bone regeneration applications, the various environmental factors including bioactive compounds such as growth factors, chemicals and physical characteristics of biointerfaces are the key factors in controlling and regulating osteogenic differentiation from MSCs. In our study, we have investigated the influence of Lactoferrin (Lf) and Hydroxyapatite (HA) embedded within a biodegradable PEG-PCL copolymer on the osteogenic fate of MSCs, previous studies revealing an anti-inflammatory potential of the coating and osteogenic differentiation of murine pre-osteoblast cells. The copolymer matrix was obtained by the Matrix Assisted Pulsed Laser Evaporation technique (MAPLE) and the composite layers containing the bioactive compounds (Lf, HA, and Lf-HA) were characterised by Scanning Electron Microscopy and Atomic Force Microscopy. Energy-dispersive X-ray spectroscopy contact angle and surface energy of the analysed coatings were also measured. The characteristics of the composite surfaces were correlated with the viability, proliferation, and morphology of human MSCs (hMSCs) cultured on the developed coatings. All surfaces were found not to exhibit toxicity, as confirmed by the LIVE/DEAD assay. The Lf-HA composite exhibited an increase in osteogenic differentiation of hMSCs, results supported by alkaline phosphatase and mineralisation assays. This is the first report of the capacity of biodegradable composite layers containing Lf to induce osteogenic differentiation from hMSCs, a property revealing its potential for application in bone regeneration.

Lactoferrin-Hydroxyapatite Containing Spongy-Like Hydrogels for Bone Tissue Engineering

The development of bioactive and cell-responsive materials has fastened the field of bone tissue engineering. Gellan gum (GG) spongy-like hydrogels present high attractive properties for the tissue engineering field, especially due to their wide microarchitecture and tunable mechanical properties, as well as their ability to entrap the responsive cells. Lactoferrin (Lf) and Hydroxyapatite (HAp) are bioactive factors that are known to potentiate faster bone regeneration. Thus, we developed an advanced three-dimensional (3D) biomaterial by integrating these bioactive factors within GG spongy-like hydrogels. Lf-HAp spongy-like hydrogels were characterized in terms of microstructure, water uptake, degradation, and concomitant release of Lf along the time. Human adipose-derived stem cells (hASCs) were seeded and the capacity of these materials to support hASCs in culture for 21 days was assessed. Lf addition within GG spongy-like hydrogels did not change the main features of GG spongy-like hydrogels in terms of porosity, pore size, degradation, and water uptake commitment. Nevertheless, HAp addition promoted an increase of the pore wall thickness (from ~13 to 28 µm) and a decrease on porosity (from ~87% to 64%) and mean pore size (from ~12 to 20 µm), as well as on the degradability and water retention capabilities. A sustained release of Lf was observed for all the formulations up to 30 days. Cell viability assays showed that hASCs were viable during the culture period regarding cell-laden spongy-like hydrogels. Altogether, we demonstrate that GG spongy-like hydrogels containing HAp and Lf in high concentrations gathered favorable 3D bone-like microenvironment with an increased hASCs viability with the presented results.

Study of physico-chemical properties and in vitro antimicrobial activity of hydroxyapatites obtained from bone calcination

Hydroxyapatite was obtained by bone calcinations. To study the calcination process, bovine and porcine bones were first autoclaved to remove fat and other non-bone tissues. They were then heated in an alumina pan in an oxidizing atmosphere of air, where simultaneous thermal analysis curves were recorded. To prepare the hydroxyapatites, bone samples were calcined at 850 °C and 1000 °C using a muffle furnace for 1 h. The obtained materials were powdered using mortar and pestle, and sifted in a sieve (60 mesh) without any additional purification or chemical treatment. The materials obtained were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The antimicrobial properties of these materials were determined through direct contact tests against Staphylococcus aureus. The natural hydroxyapatites obtained by bone calcination inhibited S. aureus growth, with the material obtained by calcination of bovine bones at 1000 °C, showing the best antimicrobial activity. These results indicated that bone wastes can be used to obtain hydroxyapatites with antimicrobial activity.

Characterization of natural hydroxyapatite originated from fish bone and its biocompatibility with osteoblasts

Hydroxyapatite (HAP) was very attractive for using as bone implant material for a long period due to the close similarity with natural bone in composition and osteoconductive properties. In this study, three kinds of natural HAP (nHAP) derived from rainbow trout (Onchorynchus mkiss), cod (Gadus) and salmon (Oncorhynchus keta) bones were prepared using thermal calcination method for the first time. Resultant nHAPs were characterized by fourier transform infrared spectroscopy (FT-IR), x-ray diffraction analysis (XRD), field-emission scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. Biocompatibility of calcined nHAP was evaluated through MTT cell viability assay and alkaline phosphatase activity experiment using mouse preosteoblast MC3T3-E1. Results of cell experiment indicated that the nHAP originated from rainbow trout and salmon bones showed better biological compatibility compared with the nHAP originated from cod bone and chemical synthetic HAP (cHAP). This is most likely attributed to the different element composition in nHAP, i.e., the nHAP derived from rainbow trout and salmon bones showed the presence of CO₃^2- and Mg²⁺. Therefore, the nHAP originated from rainbow trout and salmon bones have a great potential for application as implant material substitute in bone tissue engineering and the natural waste fish bone product can be used for hydroxyapatite synthesis as a part of bio-waste management.

A phosphorylated chitosan armed hydroxyapatite nanocomposite for advancing activity onosteoblastandosteosarcomacells

Recently, applications of traditional medicine in tissue engineering have gained increasing attention.

A New Bone Substitute Developed from 3D-Prints of Polylactide (PLA) Loaded with Collagen I: An In Vitro Study

Although a lot of research has been performed, large segmental bone defects caused by trauma, infection, bone tumors or revision surgeries still represent big challenges for trauma surgeons. New and innovative bone substitutes are needed. Three-dimensional (3D) printing is a novel procedure to create 3D porous scaffolds that can be used for bone tissue engineering. In the present study, solid discs as well as porous cage-like 3D prints made of polylactide (PLA) are coated or filled with collagen, respectively, and tested for biocompatibility and endotoxin contamination. Microscopic analyses as well as proliferation assays were performed using various cell types on PLA discs. Stromal-derived factor (SDF-1) release from cages filled with collagen was analyzed and the effect on endothelial cells tested. This study confirms the biocompatibility of PLA and demonstrates an endotoxin contamination clearly below the FDA (Food and Drug Administration) limit. Cells of various cell types (osteoblasts, osteoblast-like cells, fibroblasts and endothelial cells) grow, spread and proliferate on PLA-printed discs. PLA cages loaded with SDF-1 collagen display a steady SDF-1 release, support cell growth of endothelial cells and induce neo-vessel formation. These results demonstrate the potential for PLA scaffolds printed with an inexpensive desktop printer in medical applications, for example, in bone tissue engineering.

Vibrational spectroscopy and imaging: applications for tissue engineering

Tissue engineering (TE) approaches strive to regenerate or replace an organ or tissue. The successful development and subsequent integration of a TE construct is contingent on a series of in vitro and in vivo events that result in an optimal construct for implantation. Current widely used methods for evaluation of constructs are incapable of providing an accurate compositional assessment without destruction of the construct. In this review, we discuss the contributions of vibrational spectroscopic assessment for evaluation of tissue engineered construct composition, both during development and post-implantation. Fourier transform infrared (FTIR) spectroscopy in the mid and near-infrared range, as well as Raman spectroscopy, are intrinsically label free, can be non-destructive, and provide specific information on the chemical composition of tissues. Overall, we examine the contribution that vibrational spectroscopy via fiber optics and imaging have to tissue engineering approaches.