Combinatorial delivery of bioactive molecules by a nanoparticle-decorated and functionalized biodegradable scaffold

Biotin-functionalized nanoparticles: an overview of recent trends in cancer detection

Electrochemical bio-sensing is a potent and efficient method for converting various biological recognition events into voltage, current, and impedance electrical signals. Biochemical sensors are now a common part of medical applications, such as detecting blood glucose levels, detecting food pathogens, and detecting specific cancers. As an exciting feature, bio-affinity couples, such as proteins with aptamers, ligands, paired nucleotides, and antibodies with antigens, are commonly used as bio-sensitive elements in electrochemical biosensors. Biotin-avidin interactions have been utilized for various purposes in recent years, such as targeting drugs, diagnosing clinically, labeling immunologically, biotechnology, biomedical engineering, and separating or purifying biomolecular compounds. The interaction between biotin and avidin is widely regarded as one of the most robust and reliable noncovalent interactions due to its high bi-affinity and ability to remain selective and accurate under various reaction conditions and bio-molecular attachments. More recently, there have been numerous attempts to develop electrochemical sensors to sense circulating cancer cells and the measurement of intracellular levels of protein thiols, formaldehyde, vitamin-targeted polymers, huwentoxin-I, anti-human antibodies, and a variety of tumor markers (including alpha-fetoprotein, epidermal growth factor receptor, prostate-specific Ag, carcinoembryonic Ag, cancer antigen 125, cancer antigen 15-3, etc.). Still, the non-specific binding of biotin to endogenous biotin-binding proteins present in biological samples can result in false-positive signals and hinder the accurate detection of cancer biomarkers. This review summarizes various categories of biotin-functional nanoparticles designed to detect such biomarkers and highlights some challenges in using them as diagnostic tools.

Evaluating osteogenic effects associated with the incorporation of ascorbic acid in mineralized collagen scaffolds

Current treatments for craniomaxillofacial (CMF) defects motivate the design of instructive biomaterials that can promote osteogenic healing of complex bone defects. We report methods to promote in vitro osteogenesis of human mesenchymal stem cells (hMSCs) within a model mineralized collagen scaffold via the incorporation of ascorbic acid (vitamin C), a key factor in collagen biosynthesis and bone mineralization. An addition of 5 w/v% ascorbic acid into the base mineralized collagen scaffold significantly changes key morphology characteristics including porosity, macrostructure, and microstructure. This modification promotes hMSC metabolic activity, ALP activity, and hMSC-mediated deposition of calcium and phosphorous. Additionally, the incorporation of ascorbic acid influences osteogenic gene expression (BMP-2, RUNX2, COL1A2) and delays the expression of genes associated with osteoclast activity and bone resorption (OPN, CTSK), though it reduces the secretion of OPG. Together, these findings highlight ascorbic acid as a relevant component for mineralized collagen scaffold design to promote osteogenic differentiation and new bone formation for improved CMF outcomes.

The Delivery and Activation of Growth Factors Using Nanomaterials for Bone Repair

Bone regeneration is a comprehensive process that involves different stages, and various growth factors (GFs) play crucial roles in the entire process. GFs are currently widely used in clinical settings to promote bone repair; however, the direct application of GFs is often limited by their fast degradation and short local residual time. Additionally, GFs are expensive, and their use may carry risks of ectopic osteogenesis and potential tumor formation. Nanomaterials have recently shown great promise in delivering GFs for bone regeneration, as they can protect fragile GFs and control their release. Moreover, functional nanomaterials can directly activate endogenous GFs, modulating the regeneration process. This review provides a summary of the latest advances in using nanomaterials to deliver exogenous GFs and activate endogenous GFs to promote bone regeneration. We also discuss the potential for synergistic applications of nanomaterials and GFs in bone regeneration, along with the challenges and future directions that need to be addressed.

Poly-ε-caprolactone/poly(rotaxane) seeded with human dental pulp stem cells or osteoblasts promotes angiogenesis: a chorioallantoic membrane assay

Biomaterials used for tissue regeneration should ideally provide a favorable environment for cell proliferation and differentiation. Angiogenesis is crucial for supplying oxygen and nutrients necessary for cellular survival at implantation sites. The aim of this study was to evaluate the overall angiogenesis response of a poly ε-caprolactone/poly (rotaxane) blend (poly-blend) carried by human dental pulp stem cells (hDPSCs) or osteoblasts (OB) seeded in the chorioallantoic membranes (CAM) of fertilized chicken eggs on embryonic day 7. They were classified into the following intervention groups: (a) poly(polymeric blend disks free of cells); (b) hDPSC seeded onto CAM; (c) poly/hDPSC (where hDPSCs were seeded onto poly-blend); (d) poly/OB (where osteoblasts were seeded onto poly); (e) OB (where hDPSCs differentiated into osteoblasts were seeded onto CAM); and (f) a negative control when a sterilized silicone ring free of cells or polymer was inserted into CAM. On embryonic day 14, the quantitative and qualitative characteristics of the blood vessels in the CAMs were analyzed macroscopically and microscopically. Macroscopic examination showed that the Poly/hDPSC samples exhibited an increased medium vessel density. Additionally, microscopic observations showed that the Poly/hDPSC group and poly alone resulted in a large lumen area of vascularization. Thus, poly ε-caprolactone/poly (rotaxane) did not impair angiogenesis. Furthermore, poly-blend carried by stem cells of dental pulp origin shows a better vasculogenic potential, which is essential for regenerative therapies.

Biomaterial-targeted precision nanoparticle delivery to the injured spinal cord

Drug delivery requires precision in timing, location, and dosage to achieve therapeutic benefits. Challenges in addressing all three of these critical criteria result in poor temporal dexterity, widespread accumulation and off-target effects, and high doses with the potential for toxicity. To address these challenges, we have developed the BiomatErial Accumulating Carriers for On-demand Nanotherapy (BEACON) platform that utilizes an implantable biomaterial to serve as a target for systemically delivered nanoparticles (NPs). With the BEACON system, administered NPs are conjugated with a ligand that has high affinity for a receptor in the implanted biomaterial. To test BEACON, an in vivo spinal cord injury (SCI) model was used as it provides an injury model where the three identified criteria can be tested as it is a dynamic and complicated injury model with no currently approved therapies. Through our work, we have demonstrated temporal dexterity in NP administration by injecting 6 days post-SCI, decreased off-target accumulation with a significant drop in liver accumulation, and retention of our NPs in the target biomaterial. The BEACON system can be applied broadly, beyond the nervous system, to improve systemically delivered NP accumulation at an implanted biomaterial target. STATEMENT OF SIGNIFICANCE: Targeted drug delivery approaches have the potential to improve therapeutic regimens for patients on a case-by-case basis. Improved localization of a therapeutic to site of interest can result in increased efficacy and limit the need for repeat dosing. Unfortunately, targeted strategies can fall short when receptors on cells or tissues are too widespread or change over the course of disease or injury progression. The BEACON system developed herein eliminates the need to target a cell or tissue receptor by targeting an implantable biomaterial with location-controllable accumulation and sustained presentation over time. The targeting paradigm presented by BEACON is widely applicable throughout tissue engineering and regenerative medicine without the need to retool for each new application.

Recent Advances in the Surface Functionalization of PLGA-Based Nanomedicines

Therapeutics are habitually characterized by short plasma half-lives and little affinity for targeted cells. To overcome these challenges, nanoparticulate systems have entered into the disease arena. Poly(d,l-lactide-co-glycolide) (PLGA) is one of the most relevant biocompatible materials to construct drug nanocarriers. Understanding the physical chemistry of this copolymer and current knowledge of its biological fate will help in engineering efficient PLGA-based nanomedicines. Surface modification of the nanoparticle structure has been proposed as a required functionalization to optimize the performance in biological systems and to localize the PLGA colloid into the site of action. In this review, a background is provided on the properties and biodegradation of the copolymer. Methods to formulate PLGA nanoparticles, as well as their in vitro performance and in vivo fate, are briefly discussed. In addition, a special focus is placed on the analysis of current research in the use of surface modification strategies to engineer PLGA nanoparticles, i.e., PEGylation and the use of PEG alternatives, surfactants and lipids to improve in vitro and in vivo stability and to create hydrophilic shells or stealth protection for the nanoparticle. Finally, an update on the use of ligands to decorate the surface of PLGA nanomedicines is included in the review.

Design and applications of protein delivery systems in nanomedicine and tissue engineering

Proteins are biological macromolecules involved in a wide range of biological functions, which makes them very appealing as therapeutics agents. Indeed, compared to small molecule drugs, their endogenous nature ensures their biocompatibility and biodegradability, they can be used in a large range of applications and present a higher specificity and activity. However, they suffer from unfolding, enzymatic degradation, short half-life and poor membrane permeability. To overcome such drawbacks, the development of protein delivery systems to protect, carry and deliver them in a controlled way have emerged importantly these last years. In this review, the formulation of a wide panel of protein delivery systems either in the form of polymer or inorganic nanoengineered colloids and scaffolds are presented and the protein loading and release mechanisms are addressed. A section is also dedicated to the detection of proteins and the characterization methods of their release. Then, the main protein delivery systems developed these last three years for anticancer, tissue engineering or diabetes applications are presented, as well as the major in vivo models used to test them. The last part of this review aims at presenting the perspectives of the field such as the use of protein-rich material or the sequestration of proteins. This part will also deal with less common applications and gene therapy as an indirect method to deliver protein.

Poly-(Lactic-co-Glycolic) Acid Nanoparticles for Synergistic Delivery of Epirubicin and Paclitaxel to Human Lung Cancer Cells

Combination therapy using chemically distinct drugs has appeared as one of the promising strategies to improve anticancer treatment efficiency. In the present investigation, poly-(lactic-co-glycolic) acid (PLGA) nanoparticles electrostatically conjugated with polyethylenimine (PEI)-based co-delivery system for epirubicin and paclitaxel (PLGA-PEI-EPI-PTX NPs) has been developed. The PLGA-PEI-EPI-PTX NPs exhibited a monodispersed size distribution with an average size of 240.93 ± 12.70 nm as measured through DLS and 70.8-145 nm using AFM. The zeta potential of 41.95 ± 0.65 mV from -17.45 ± 2.15 mV further confirmed the colloidal stability and PEI modification on PLGA nanoparticles. Encapsulation and loading efficiency along with in vitro release of drug for nanoparticles were done spectrophotometrically. The FTIR analysis of PLGA-PEI-EPI-PTX NPs revealed the involvement of amide moiety between polymer PLGA and PEI. The effect of nanoparticles on the cell migration was also corroborated through wound healing assay. The MTT assay demonstrated that PLGA-PEI-EPI-PTX NPs exhibited considerable anticancer potential as compared to the naïve drugs. Further, p53 protein expression analysed through western blot showed enhanced expression. This study suggests that combination therapy using PLGA-PEI-EPI-PTX NPs represent a potential approach and could offer clinical benefits in the future for lung cancer patients.

Nanoclay-based 3D printed scaffolds promote vascular ingrowth ex vivo and generate bone mineral tissue in vitro and in vivo

Acellular soft hydrogels are not ideal for hard tissue engineering given their poor mechanical stability, however, in combination with cellular components offer significant promise for tissue regeneration. Indeed, nanocomposite bioinks provide an attractive platform to deliver human bone marrow stromal cells (HBMSCs) in three dimensions producing cell-laden constructs that aim to facilitate bone repair and functionality. Here we present the in vitro, ex vivo and in vivo investigation of bioprinted HBMSCs encapsulated in a nanoclay-based bioink to produce viable and functional three-dimensional constructs. HBMSC-laden constructs remained viable over 21 d in vitro and immediately functional when conditioned with osteogenic media. 3D scaffolds seeded with human umbilical vein endothelial cells (HUVECs) and loaded with vascular endothelial growth factor (VEGF) implanted ex vivo into a chick chorioallantoic membrane (CAM) model showed integration and vascularisation after 7 d of incubation. In a pre-clinical in vivo application of a nanoclay-based bioink to regenerate skeletal tissue, we demonstrated bone morphogenetic protein-2 (BMP-2) absorbed scaffolds produced extensive mineralisation after 4 weeks (p < 0.0001) compared to the drug-free and alginate controls. In addition, HBMSC-laden 3D printed scaffolds were found to significantly (p < 0.0001) support bone tissue formation in vivo compared to acellular and cast scaffolds. These studies illustrate the potential of nanoclay-based bioink, to produce viable and functional constructs for clinically relevant skeletal tissue regeneration.

In vivo delivery of VEGF RNA and protein to increase osteogenesis and intraosseous angiogenesis

Deficient bone vasculature is a key component in pathological conditions ranging from developmental skeletal abnormalities to impaired bone repair. Vascularisation is dependent upon vascular endothelial growth factor (VEGF), which drives both angiogenesis and osteogenesis. The aim of this study was to examine the efficacy of blood vessel and bone formation following transfection with VEGF RNA or delivery of recombinant human VEGF165 protein (rhVEGF165) across in vitro and in vivo model systems. To quantify blood vessels within bone, an innovative approach was developed using high-resolution X-ray computed tomography (XCT) to generate quantifiable three-dimensional reconstructions. Application of rhVEGF165 enhanced osteogenesis, as evidenced by increased human osteoblast-like MG-63 cell proliferation in vitro and calvarial bone thickness following in vivo administration. In contrast, transfection with VEGF RNA triggered angiogenic effects by promoting VEGF protein secretion from MG-63VEGF165 cells in vitro, which resulted in significantly increased angiogenesis in the chorioallantoic (CAM) assay in ovo. Furthermore, direct transfection of bone with VEGF RNA in vivo increased intraosseous vascular branching. This study demonstrates the importance of continuous supply as opposed to a single high dose of VEGF on angiogenesis and osteogenesis and, illustrates the potential of XCT in delineating in 3D, blood vessel connectivity in bone.

Printing bone in a gel: using nanocomposite bioink to print functionalised bone scaffolds

Free-form printing offers a novel biofabrication approach to generate complex shapes by depositing hydrogel materials within a temporary supportive environment. However, printed hydrogels typically lack the requisite mechanical properties and functionality of the desired tissue, limiting application and, more importantly, safety and efficacy of the implant. The study authors have developed an innovative nanoclay-based bioink to print high shape fidelity functional constructs for potential skeletal application. Laponite® (LAP) nanoclay was combined with gellan gum (GG) to generate a printable hydrogel that was highly stable in vitro, displayed limited swelling ability compared with the silicate-free control and remained stable over time. An agarose fluid gel was found to provide the requisite support for the deposition of the material ink and preservation of the printed structure before crosslinking. Printed C2C12 myoblasts remained viable and displayed extensive proliferation over 21 days in culture. Cell-laden scaffolds demonstrated functionality within 1 day of culture in vitro and that was preserved over 3 weeks. Analysis of absorption and release mechanisms from LAP-GG using model proteins (lysozyme and bovine serum albumin) demonstrated the retention capability of the clay-based materials for compound localisation and absence of burst release. Vascular endothelial growth factor ​was loaded within the agarose fluid gel and absorbed by the material ink via absorption during deposition. The 3D-printed constructs were implanted on the chorioallantoic membrane of a 10-day-old developing chick. Extensive and preferential vasculature infiltration was observed in LAP-GG-loaded vascular endothelial growth factor constructs compared with controls (p<0.01 and p<0.0001) after only 7 days of incubation. The current studies demonstrate, for the first time, the application of innovative LAP-GG 3D constructs in the generation of growth factor-loaded 3D constructs for potential application in skeletal tissue repair.

Fabrication of a nanoparticle-containing 3D porous bone scaffold with proangiogenic and antibacterial properties

3D porous scaffolds based on agarose and nanocrystalline apatite, two structural components that act as a temporary mineralized extracellular matrix, were prepared by the GELPOR3D method. This shaping technology allows the introduction of thermally-labile molecules within the scaffolds during the fabrication procedure. An angiogenic protein, Vascular Endothelial Growth Factor, and an antibiotic, cephalexin, loaded in mesoporous silica nanoparticles, were included to design multifunctional scaffolds for bone reconstruction. The dual release of both molecules showed a marked increase in the number of blood vessels on embryonic day 14 in chicken embryos grown ex ovo, while, at the same time providing an antibiotic local concentration capable of inhibiting Staphylococcus aureus bacterial growth. In this sense, different release patterns, monitored by UV-spectroscopy, could be tailored as a function of the cephalexin loading strategy, either releasing all the loaded cephalexin in the first 4 h or less than 50% after 24 h. The scaffold surface was characterized by a high hydrophilicity, with contact angles between 50° and 63°, which enabled the adhesion and proliferation of preosteoblastic cells. STATEMENT OF SIGNIFICANCE: The localized delivery of bioactive molecules has attracted significant attention due to the potential for dose reduction as well as reduced side effects compared to systemic delivery. In this article multifunctional 3D porous scaffolds with a designed porosity have been fabricated. The method also enables the controlled loading of an antibiotic drug and an angiogenic protein into the scaffold. These scaffolds, whose composition resembles the extracellular matrix are suitable for the adhesion of preosteoblast cells, exhibit a sustained cephalexin delivery adequate for inhibiting bacterial growth as well as release the proangiogenic molecule which induces blood vessel formation in chicken embryos grown ex ovo.