Controlled release of insulin from self-assembling nanofiber hydrogel, PuraMatrix™: application for the subcutaneous injection in rats

A Review of Sustained Drug Release Studies from Nanofiber Hydrogels

Polymer nanofibers have exceptionally high surface area. This is advantageous compared to bulk polymeric structures, as nanofibrils increase the area over which materials can be transported into and out of a system, via diffusion and active transport. On the other hand, since hydrogels possess a degree of flexibility very similar to natural tissue, due to their significant water content, hydrogels made from natural or biodegradable macromolecular systems can even be injectable into the human body. Due to unique interactions with water, hydrogel transport properties can be easily modified and tailored. As a result, combining nanofibers with hydrogels would truly advance biomedical applications of hydrogels, particularly in the area of sustained drug delivery. In fact, certain nanofiber networks can be transformed into hydrogels directly without the need for a hydrogel enclosure. This review discusses recent advances in the fabrication and application of biomedical nanofiber hydrogels with a strong emphasis on drug release. Most of the drug release studies and recent advances have so far focused on self-gelling nanofiber systems made from peptides or other natural proteins loaded with cancer drugs. Secondly, polysaccharide nanofiber hydrogels are being investigated, and thirdly, electrospun biodegradable polymer networks embedded in polysaccharide-based hydrogels are becoming increasingly popular. This review shows that a major outcome from these works is that nanofiber hydrogels can maintain drug release rates exceeding a few days, even extending into months, which is an extremely difficult task to achieve without the nanofiber texture. This review also demonstrates that some publications still lack careful rheological studies on nanofiber hydrogels; however, rheological properties of hydrogels can influence cell function, mechano-transduction, and cellular interactions such as growth, migration, adhesion, proliferation, differentiation, and morphology. Nanofiber hydrogel rheology becomes even more critical for 3D or 4D printable systems that should maintain sustained drug delivery rates.

Nanofiber-based systems intended for diabetes

Diabetic mellitus (DM) is the most communal metabolic disease resulting from a defect in insulin secretion, causing hyperglycemia by promoting the progressive destruction of pancreatic β cells. This autoimmune disease causes many severe disorders leading to organ failure, lower extremity amputations, and ultimately death. Modern delivery systems e.g., nanofiber (NF)-based systems fabricated by natural and synthetic or both materials to deliver therapeutics agents and cells, could be the harbinger of a new era to obviate DM complications. Such delivery systems can effectively deliver macromolecules (insulin) and small molecules. Besides, NF scaffolds can provide an ideal microenvironment to cell therapy for pancreatic β cell transplantation and pancreatic tissue engineering. Numerous studies indicated the potential usage of therapeutics/cells-incorporated NF mats to proliferate/regenerate/remodeling the structural and functional properties of diabetic skin ulcers. Thus, we intended to discuss the aforementioned features of the NF system for DM complications in detail.

Production and Immunogenicity of a Tag-Free Recombinant Chimera Based on PfMSP-1 and PfMSP-3 Using Alhydrogel and Dipeptide-Based Hydrogels

A fusion chimeric vaccine comprising multiple protective domains of different blood-stage Plasmodium falciparum antigens is perhaps necessary for widening the protective immune responses and reducing the morbidity caused by the disease. Here we continue to build upon the prior work of developing a recombinant fusion chimera protein, His-tagged PfMSP-Fu24, by producing it as a tag-free recombinant protein. In this study, tag-free recombinant PfMSPFu24 (rFu24) was expressed in Escherichia coli, and the soluble protein was purified using a three-step purification involving ammonium sulphate precipitation followed by 2-step ion exchange chromatography procedures and shown that it was highly immunogenic with the human-compatible adjuvant Alhydrogel. We further investigated two dipeptides, phenylalanine-α, β-dehydrophenylalanine (FΔF) and Leucine-α, β-dehydrophenylalanine (LΔF) based hydrogels as effective delivery platforms for rFu24. These dipeptides self-assembled spontaneously to form a highly stable hydrogel under physiological conditions. rFu24 was efficiently entrapped in both the F∆F and L∆F hydrogels, and the three-dimensional (3D) mesh-like structures of the hydrogels remained intact after the entrapment of the antigen. The two hydrogels significantly stimulated rFu24-specific antibody titers, and the sera from the immunized mice showed an invasion inhibitory activity comparable to that of Alhydrogel. Easily synthesized dipeptide hydrogels can be used as an effective antigen delivery platform to induce immune responses.

Modeling the photodynamic effect in 2D versus 3D cell culture under normoxic and hypoxic conditions

BACKGROUND

Photodynamic therapy (PDT), mainly as a combined therapy, can still be considered a promising technology for targeted cancer treatment. Besides the several and essential benefits of PDT, there are some concerns and limitations, such as complex dosimetry, tumor hypoxia, and other mechanisms of resistance. In this study, we present how the cell culture model and cell culture conditions may affect the response to PDT treatment. It was studied by applying two different 3D cell culture, non-scaffold, and hydrogel-based models under normoxic and hypoxic conditions. In parallel, a detailed mechanism of the action of zinc phthalocyanine M2TG3 was presented.

METHODS

Hydrogel-based and tumor spheroids consisting of LNCaP cells, were used as 3D cell culture models in experiments performed under normoxic and hypoxic (1% of oxygen) conditions. Several analyses were performed to compare the activity of M2TG3 under different conditions, such as cytotoxicity, the level of proapoptotic and stress-related proteins, caspase activity, and antioxidant gene expression status. Additionally, we tested bioluminescence and fluorescence assays as a useful approach for a hydrogel-based 3D cell culture.

RESULTS

We found that M2TG3 might lead to apoptotic cancer cell death and is strongly dependent on the model and oxygen availability. Moreover, the expression of the genes modulated in the antioxidative system in 2D and 3D cell culture models were presented. The tested bioluminescence assay revealed several advantages, such as repetitive measurements on the same sample and simultaneous analysis of different parameters due to the non-lysing nature of this assay.

CONCLUSIONS

It was shown that M2TG3 can effectively cause cancer cell death via a different mechanism, depending on cell culture conditions such as the model and oxygen availability.

Polymer-loaded hydrogels serve as depots for lactate and mimic "cold" tumor microenvironments

The burgeoning field of biomaterials for immunotherapy has aided in the understanding of foundational mechanisms of cancer immunology. In particular, implantable biomaterials can be engineered to investigate specific aspects of the tumor microenvironment either singularly or in combination. Of note, the metabolite - lactate, a byproduct of anaerobic glycolysis, is known to reprogram immune cells, resulting in increased tumor survival. An adequate model that can recapitulate intratumoral lactate concentrations does not exist. In this study, we demonstrate that a simple biomaterial platform could be developed as an instructive tool to decipher the effects of lactate in vivo. Briefly, we demonstrate that a peptide hydrogel loaded with granulocyte-macrophage colony stimulating factor and poly-(lactic-co-glycolic acid)/(lactic acid) microparticles can generate the localized lactate concentrations (∼2-22 mM) and cellular makeup of the tumor microenvironment, following subcutaneous implantation in mice. Furthermore, infiltrating immune cells adopt phenotypes similar to those seen in other in vitro and in vivo cancer models, including immunosupressive dendritic cells. This hydrogel system is a framework to interrogate immune cell modulation in cancer-like environments using safe and degradable biomaterials. Moreover, this system can be multifaceted, as incorporation of other cancer tumor environmental factors or chemotherapeutic drugs is facile and could be insightful in developing or improving immunotherapies.

Self-Assembling Peptide Scaffold Carrying Neural-Cell Adhesion Molecule-Derived Mimetic-Peptide Transplantation Promotes Proliferation and Stimulates Neurite Extension by Modulating Tau Phosphorylation and Calpain/Glycogen Synthase Kinase 3 beta (GSK-3β) in Neurons

BACKGROUND Self-assembling peptide scaffolds have been extensively applied in tissue engineering. Many investigations have modified self-assembling peptide scaffolds by integrating functional motifs, with promising applications. This study aimed to generate a novel RADA16 self-assembling peptide scaffold integrating a neural-cell adhesion molecule-derived mimetic-peptide (SIDRVEPYSSTAQ) and evaluated the effects on neuron proliferation. MATERIAL AND METHODS A 37-amino-acids peptide of RADA16-activation motif containing neural-cell adhesion molecule-derived mimetic-peptide (SIDRVEPYSSTAQ) was synthesized and self-assembled into a scaffold. Dorsal root ganglion (DRG) and spinal cord motor neurons (SCMN) were primarily isolated and identified. Neurons (DRG and SCMN) were divided into FRM, FRM-MP, and FRM-MP-LiCl groups. The adherence ability of neurons was evaluated using toluidine blue staining. Proliferation and apoptosis of neurons were assessed using CCK-8 and flow cytometry assay, respectively. Immunofluorescence assay was used to measure neurite extension. Western blot assay was used to assess GSK-3ß/p-GSK-3ß, Tau/p-Tau, and calpain expression in neurons. RESULTS FRM-MP-LiCl released multiple-peptide with higher efficiency. FRM-MP-LiCl significantly enhanced proliferation and inhibited apoptosis compared to FRM and FRM-MP groups (p.

Mechanistic investigations into the encapsulation and release of small molecules and proteins from a supramolecular nucleoside gel in vitro and in vivo

Supramolecular gels have recently emerged as promising biomaterials for the delivery of a wide range of bioactive molecules, from small hydrophobic drugs to large biomolecules such as proteins. Although it has been demonstrated that each encapsulated molecule has a different release profile from the hydrogel, so far diffusion and steric impediment have been identified as the only mechanisms for the release of molecules from supramolecular gels. Erosion of a supramolecular gel has not yet been reported to contribute to the release profiles of encapsulated molecules. Here, we use a novel nucleoside-based supramolecular gel as a drug delivery system for proteins with different properties and a hydrophobic dye and describe for the first time how these materials interact, encapsulate and eventually release bioactive molecules through an erosion-based process. Through fluorescence microscopy and spectroscopy as well as small angle X-ray scattering, we show that the encapsulated molecules directly interact with the hydrogel fibres - rather than being physically entrapped in the gel network. The ability of these materials to protect proteins against enzymatic degradation is also demonstrated here for the first time. In addition, the released proteins were proven to be functional in vitro. Real-time fluorescence microscopy together with macroscopic release studies confirm that erosion is the key release mechanism. In vivo, the gel completely degrades after two weeks and no signs of inflammation are detected, demonstrating its in vivo safety. By establishing the contribution of erosion as a key driving force behind the release of bioactive molecules from supramolecular gels, this work provides mechanistic insight into the way molecules with different properties are encapsulated and released from a nucleoside-based supramolecular gel and sets the basis for the design of more tailored supramolecular gels for drug delivery applications.

Sema4D/PlexinB1 promotes endothelial differentiation of dental pulp stem cells via activation of AKT and ERK1/2 signaling

Inducing of dental pulp stem cells (DPSCs) into endothelial cells (ECs) to prevascularize pulp tissue constructs may offer a novel and viable approach for enhancing pulp regeneration. However, there are numerous challenges in current methods for the acquisition of sufficient translational ECs. It was known that Sema4D/PlexinB1 signaling exerts profound effects on enhancing vascular endothelial growth factor (VEGF) secretion and angiogenesis. Whether Sema4D/PlexinB1 could regulate endothelial differentiation of DPSCs is not yet investigated. In this study, when DPSCs were treated with Sema4D (2 μg/mL), ECs-specific (VEGFR1, VEGFR2, CD31, and vWF), and angiogenic genes and proteins were significantly upregulated. The induced ECs exhibited similar endothelial vessel formation ability to that of human umbilical vein endothelial cells (HUVECs). Furthermore, phosphorylation of AKT increased dramatically within 5 minutes (from 0.93 to 21.8), while p-ERK1/2 was moderately elevated (from 0.94 to 2.65). In summary, our results demonstrated that Sema4D/PlexinB1 signaling induces endothelial differentiation of DPSCs. The interactions of Sema4D, VEGF, ANGPTL4, ANG1, and HIF-1α may play a crucial role in mediating the differentiation process.

Supramolecular biofunctional materials

This review discusses supramolecular biofunctional materials, a novel class of biomaterials formed by small molecules that are held together via noncovalent interactions. The complexity of biology and relevant biomedical problems not only inspire, but also demand effective molecular design for functional materials. Supramolecular biofunctional materials offer (almost) unlimited possibilities and opportunities to address challenging biomedical problems. Rational molecular design of supramolecular biofunctional materials exploit powerful and versatile noncovalent interactions, which offer many advantages, such as responsiveness, reversibility, tunability, biomimicry, modularity, predictability, and, most importantly, adaptiveness. In this review, besides elaborating on the merits of supramolecular biofunctional materials (mainly in the form of hydrogels and/or nanoscale assemblies) resulting from noncovalent interactions, we also discuss the advantages of small peptides as a prevalent molecular platform to generate a wide range of supramolecular biofunctional materials for the applications in drug delivery, tissue engineering, immunology, cancer therapy, fluorescent imaging, and stem cell regulation. This review aims to provide a brief synopsis of recent achievements at the intersection of supramolecular chemistry and biomedical science in hope of contributing to the multidisciplinary research on supramolecular biofunctional materials for a wide range of applications. We envision that supramolecular biofunctional materials will contribute to the development of new therapies that will ultimately lead to a paradigm shift for developing next generation biomaterials for medicine.

Vaccine Adjuvant Nanotechnologies

The increasing sophistication of vaccine adjuvant design has been driven by improved understanding of the importance of nanoscale features of adjuvants to their immunological function. Newly available advanced nanomanufacturing techniques now allow very precise control of adjuvant particle size, shape, texture, and surface chemistry. Novel adjuvant concepts include self-assembling particles and targeted immune delivery. These individual concepts can be combined to create a single integrated vaccine nanoparticle-combining antigen, adjuvants, and DC-targeting elements. In the process, the concept of an adjuvant has broadened to include not only immune-stimulatory substances but also any design features that enhance the immune response against the relevant vaccine antigen. The modern definition of an adjuvant includes not only classical immune stimulators but also any aspects of particle size, shape, and surface chemistry that enhance vaccine immunogenicity. It even includes purely physical processes such as texturing of particle surfaces to maximize immunogenicity. Looking forward, adjuvants will increasingly be seen not as separate add-on items but as wholly integrated elements of a complete vaccine delivery package. Hence, vaccine systems will increasingly approach the complexity and sophistication of pathogens themselves, incorporating highly specific particle properties, contents, and behaviors, all designed to maximize immune system recognition and drive the immune response in the specific direction that affords maximal protection.

Antimicrobial Nanostructures for Neurodegenerative Infections

Nanostructures have been widely involved in changes in the drug delivery system. Nanoparticles have unique physicochemical properties, e.g., ultrasmall size, large surface area, and the ability to target specific actions. Various nanomaterials, like Ag, ZnO, Cu/CuO, and Al₂O₃, have antimicrobial activity. Basically, six mechanisms are involved in the production of antimicrobial activity, i.e., (1) destruction of the peptidoglycan layer, (2) release of toxic metal ions, (3) alteration of cellular pH via proton efflux pumps, (4) generation of reactive oxygen species, (5) damage of nuclear materials, and (6) loss of ATP production. Nanomedicine contributes to various pharmaceutical applications, like diagnosis and treatment of various ailments including microbial diseases. Furthermore, nanostructured antimicrobial agents are also involved in the treatment of the neuroinfections associated with neurodegenerative disorders. This chapter focuses on the nanostructure and nanomedicine of antimicrobial agents and their prospects for the possible management of infections associated with neurodegenerative disorders.

Controlled release of TGF-beta 1 from RADA self-assembling peptide hydrogel scaffolds

Bioactive mediators, cytokines, and chemokines have an important role in regulating and optimizing the synergistic action of materials, cells, and cellular microenvironments for tissue engineering. RADA self-assembling peptide hydrogels have been proved to have an excellent ability to promote cell proliferation, wound healing, tissue repair, and drug delivery. Here, we report that D-RADA16 and L-RADA16-RGD self-assembling peptides can form stable second structure and hydrogel scaffolds, affording the slow release of growth factor (transforming growth factor cytokine-beta 1 [TGF-beta 1]). In vitro tests demonstrated that the plateau release amount can be obtained till 72 hours. Moreover, L-RADA16, D-RADA16, and L-RADA16-RGD self-assembling peptide hydrogels containing TGF-beta 1 were used for 3D cell culture of bone mesenchymal stem cells of rats for 2 weeks. The results revealed that these three RADA16 peptide hydrogels had a significantly favorable influence on proliferation of bone mesenchymal stem cells and hold some promise in slow and sustained release of growth factor.

Peptide-Based Supramolecular Hydrogels for Delivery of Biologics

The demand for therapeutic biologics has rapidly grown over recent decades, creating a dramatic shift in the pharmaceutical industry from small molecule drugs to biological macromolecular therapeutics. As a result of their large size and innate instability, the systemic, topical, and local delivery of biologic drugs remains a highly challenging task. Although there exist many types of delivery vehicles, peptides and peptide conjugates have received continuously increasing interest as molecular blocks to create a great diversity of supramolecular nanostructures and hydrogels for the effective delivery of biologics, due to their inherent biocompatibility, tunable biodegradability, and responsiveness to various biological stimuli. In this context, we discuss the design principles of supramolecular hydrogels using small molecule peptides and peptide conjugates as molecular building units, and review the recent effort in using these materials for protein delivery and gene delivery.

Intraosseous Delivery of Bone Morphogenic Protein-2 Using a Self-Assembling Peptide Hydrogel

Osteonecrosis of the femoral head (ONFH) is a debilitating hip disorder, which often produces a permanent femoral head deformity and osteoarthritis. The local delivery of biological agents capable of stimulating bone healing offer potential new treatment options for patients with ONFH. Previous studies from our laboratory have shown that a local intraosseous infusion of bone morphogenic protein-2 (BMP-2) was effective in stimulating new bone formation in a piglet model of ischemic ONFH. However, infusion of BMP-2 solution was associated with unwanted dissemination of BMP-2 out of the femoral head and produced heterotopic ossification in the hip capsule. Injectable hydrogels offer a potential method to control the dissemination of biological molecules in vivo. In the present study, we evaluated the potential of a peptide-based, self-assembling hydrogel called RADA16 to transition from a solution to a gel following infusion into the femoral head, thereby preventing backflow, as well as its potential use as a delivery vehicle for BMP-2. Cadaver pig femoral heads were used to study the backflow and the distribution of RADA16 following an intraosseous infusion. Microcomputed tomography analysis following the infusion of RADA16 mixed with a radiocontrast agent revealed a significant decrease in the amount of back flow of radiocontrast agent down the needle track compared to the soluble infusion of radiocontrast without RADA16. Furthermore, RADA16 mixed with radiocontrast agent showed good distribution within the femoral head. In addition, in vitro experiments revealed that higher concentrations of RADA16 decreased the rate of BMP-2 dissemination out of the hydrogel. The BMP-2 that was released from RADA16 maintains its biological activity, inducing the phosphorylation of SMAD1/5/8 in pig primary bone marrow stromal cells. Lastly, pig primary bone marrow stromal cells showed significantly increased in vitro proliferation on RADA16 hydrogels over 1 week compared to tissue culture plastic, suggesting that it is a suitable matrix for supporting cellular proliferation. In conclusion, RADA16 showed potential for use as a drug delivery vehicle to control the delivery of BMP-2 within the femoral head. This novel therapy may be able to provide benefits to patients suffering from debilitating conditions such as osteonecrosis of the femoral head.

Semaphorin 3C Released from a Biocompatible Hydrogel Guides and Promotes Axonal Growth of Rodent and Human Dopaminergic Neurons

Cell therapy in experimental models of Parkinson's disease replaces the lost dopamine neurons (DAN), but we still need improved methods to guide dopaminergic axons (DAx) of grafted neurons to make proper connections. The protein Semaphorin 3C (Sema3C) attracts DAN axons and enhances their growth. In this work, we show that the hydrogel PuraMatrix, a self-assembling peptide-based matrix, incorporates Sema3C and releases it steadily during 4 weeks. We also tested if hydrogel-delivered Sema3C attracts DAx using a system of rat midbrain explants embedded in collagen gels. We show that Sema3C released by this hydrogel attracts DAx, in a similar way to pretectum, which is known to attract growing DAN axons. We assessed the effect of Sema3C on the growth of DAx using microfluidic devices. DAN from rat midbrain or those differentiated from human embryonic stem cells showed enhanced axonal extension when exposed to hydrogel-released Sema3C, similar to soluble Sema3C. Notably, DAN of human origin express the cognate Sema3C receptors, Neuropilin1 and Neuropilin2. These results show that PuraMatrix is able to incorporate and release Sema3C, and such delivery guides and promotes the axonal growth of DAN. This biocompatible hydrogel might be useful as a Sema3C carrier for in vivo studies in parkinsonian animal models.

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers.

A combination hydrogel microparticle-based vaccine prevents type 1 diabetes in non-obese diabetic mice

Targeted delivery of self-antigens to the immune system in a mode that stimulates a tolerance-inducing pathway has proven difficult. To address this hurdle, we developed a vaccine based-approach comprised of two synthetic controlled-release biomaterials, poly(lactide-co-glycolide; PLGA) microparticles (MPs) encapsulating denatured insulin (key self-antigen in type 1 diabetes; T1D), and PuraMatrix^TM peptide hydrogel containing granulocyte macrophage colony-stimulating factor (GM-CSF) and CpG ODN1826 (CpG), which were included as vaccine adjuvants to recruit and activate immune cells. Although CpG is normally considered pro-inflammatory, it also has anti-inflammatory effects, including enhancing IL-10 production. Three subcutaneous administrations of this hydrogel (GM-CSF/CpG)/insulin-MP vaccine protected 40% of NOD mice from T1D. In contrast, all control mice became diabetic. In vitro studies indicate CpG stimulation increased IL-10 production, as a potential mechanism. Multiple subcutaneous injections of the insulin containing formulation resulted in formation of granulomas, which resolved by 28 weeks. Histological analysis of these granulomas indicated infiltration of a diverse cadre of immune cells, with characteristics reminiscent of a tertiary lymphoid organ, suggesting the creation of a microenvironment to recruit and educate immune cells. These results demonstrate the feasibility of this injectable hydrogel/MP based vaccine system to prevent T1D.

Comparison between self-assembling peptide nanofiber scaffold (SAPNS) and fibrin sealant in neurosurgical hemostasis

RADA16-I is a synthetic type I self-assembling peptide nanofiber scaffold (SAPNS) which may serve as a novel biocompatible hemostatic agent. Its application in neurosurgical hemostasis, however, has not been explored. Although RADA16-I is nontoxic and nonimmunogenic, its intrinsic acidity may potentially provoke inflammation in the surgically injured brain. We conducted an animal study to compare RADA16-I with fibrin sealant, a commonly used agent, with the hypothesis that the former would be a comparable alternative. Using a standardized surgical brain injury model, 30 Sprague-Dawley rats were randomized into three treatment groups: RADA16-I, fibrin sealant or gelatin sponge (control). Animals were sacrificed on day 3 and 42. Astrocytic and microglial infiltrations within the cerebral parenchyma adjacent to the operative site were significantly lower in the RADA16-I and fibrin sealant groups than control. RADA16-I did not cause more cellular inflammatory response despite its acidity when compared with fibrin sealant. Immunohistochemical studies showed infiltration by astrocytes and microglia into the fibrin sealant and RADA16-I grafts, suggesting their potential uses as tissue scaffolds. RADA16-I is a promising candidate for further translational and clinical studies that focus on its applications as a safe and effective hemostat, proregenerative nanofiber scaffold as well as drug and cell carrier.

Effective and durable genetic modification of human mesenchymal stem cells via controlled release of rAAV vectors from self-assembling peptide hydrogels with a maintained differentiation potency

Controlling the release of recombinant adeno-associated virus (rAAV) vectors from biocompatible materials is a novel, attractive approach to increase the residence time and effectiveness of a gene carrier at a defined target site. Self-assembling peptides have an ability to form stable hydrogels and encapsulate cells upon exposure to physiological pH and ionic strength. Here, we examined the capacity of the peptide hydrogel RAD16-I in a pure (RAD) form or combined with hyaluronic acid (RAD-HA) to release rAAV vectors as a means to genetically modify primary human bone marrow-derived mesenchymal stem cells (hMSCs), a potent source of cells for regenerative medicine. Specifically, we demonstrate the ability of the systems to efficiently encapsulate and release rAAV vectors in a sustained, controlled manner for the effective transduction of hMSCs (up to 80%) without deleterious effects on cell viability (up to 100%) or on their potential for chondrogenic differentiation over time (up to 21days). The present study demonstrates that RAD16-I is an advantageous material with tunable properties to control the release of rAAV vectors as a promising tool to develop new, improved therapeutic approaches for tissue engineering in vivo.

Vaccine self-assembling immune matrix is a new delivery platform that enhances immune responses to recombinant HBsAg in mice

Vaccination remains the most effective public health tool to prevent infectious diseases. Many vaccines are marginally effective and need enhancement for immunocompromised, elderly, and very young populations. To enhance immunogenicity, we exploited the biphasic property of the (RADA)4 synthetic oligopeptide to create VacSIM (vaccine self-assembling immune matrix), a new delivery method. VacSIM solution can easily be mixed with antigens, organisms, and adjuvants for injection. Postinjection, the peptides self-assemble into hydrated nanofiber gel matrices, forming a depot with antigens and adjuvants in the aqueous phase. We believe the depot provides slow release of immunogens, leading to increased activation of antigen-presenting cells that then drive enhanced immunogenicity. Using recombinant hepatitis B virus surface antigen (rHBsAg) as a model immunogen, we compared VacSIM delivery to delivery in alum or complete Freund's adjuvant (CFA). Delivery of the rHBsAg antigen to mice via VacSIM without adjuvant elicited higher specific IgG responses than when rHBsAg was delivered in alum or CFA. Evaluating IgG subtypes showed a mixed Th1/Th2 type response following immunization with VacSIM, which was driven further toward Th1 with addition of CpG as the adjuvant. Increased specific IgG endpoint titers were observed in both C57BL/6 and BALB/c mice, representative of Th1 and Th2 environments, respectively. Restimulation of splenocytes suggests that VacSIM does not cause an immediate proinflammatory response in the host. Overall, these results suggest that VacSIM, as a new delivery method, has the potential to enhance immunogenicity and efficacy of numerous vaccines.

Novel drug delivery system: an immense hope for diabetics

CONTEXT

Existing medication systems for the treatment of diabetes mellitus (DM) are inconvenient and troublesome for effective and safe delivery of drugs to the specific site. Therefore, investigations are desired to deliver antidiabetics using novel delivery approaches followed by their commercialization.

OBJECTIVE

The present review aims to provide a compilation on the latest development in the field of novel drug delivery systems (NDDSs) for antidiabetics with special emphasis on particulate, vesicular and miscellaneous systems.

METHODS

Review of literature (restricted to English language only) was done using electronic databases like Pubmed® and Scirus, i.e. published during 2005-2013. The CIMS/MIMS India Medical Drug Information eBook was used regarding available marketed formulation of antidiabetic drugs. Keywords used were "nanoparticle", "microparticle", "liposomes", "niosomes", "transdermal systems", "insulin", "antidiabetic drugs" and "novel drug delivery systems". Single inclusion was made for one article. If in vivo study was not done then article was seldom included in the manuscript.

RESULTS

The curiosity to develop NDDSs of antidiabetic drugs with special attention to the nanoparticulate system followed by microparticulate and lipid-based system is found to emerge gradually to overcome the problems associated with the conventional dosage forms and to win the confidence of end users towards the higher acceptability.

CONCLUSION

In the current scientific panorama when the area of novel drug delivery system has been recognized for its palpable benefits, unique potential of providing physical stability, sustained and site-specific drug delivery for a scheduled period of time can open new vistas for precise, safe and quality treatment of DM.

Preparation and pharmaceutical evaluation of nano-fiber matrix supported drug delivery system using the solvent-based electrospinning method

In this study, utilizing the solvent-based electrospinning (ES) method, which is mainly employed in the textile industry, we prepared nanofiber-based capsules including drugs for controlled-release delivery systems using methacrylic acid copolymer (EUDRAGIT(®) S100, MAC) as a polymer, and evaluated their in vitro drug dissolution profiles and in vivo pharmacokinetics in rats. As the model drugs, uranine (UN) was used as a water-soluble drug and nifedipine (NP) as a water-insoluble drug. The mean diameters of drug free nano-fiber and nano-fiber including NP or UN were 751.5 ± 67.2, 703.3 ± 71.2 and 2477.8 ± 206.1 nm, respectively. X-ray diffraction for the nano-fibrotic sheet showed that UN and/or NP were packed in nano-fiber in an amorphous form. The in vitro release of UN or NP from the nano-fiber packed capsules (NFPC) and milled-powder of nano-fiber packed capsules (MPPC) showed controlled release of UN or NP as compared to capsules of a physical mixture of MAC and each drug. An in vivo pharmacokinetic study in rats after intraduodenal administration of NFPC or MPPC including UN and/or NP clearly demonstrated that application of nano-fibrotic technique as a drug delivery system offers drastic changes in pharmacokinetic profiles for both water-soluble and water-insoluble drugs. The ES method is a useful technique to prepare a nano-fiber like solid dispersion for polar or nonpolar drugs, and has wide potential pharmaceutical applications.

Availability of polymeric nanoparticles for specific enhanced and targeted drug delivery

Over the past 20–30 years there has been quite a number of studies interested in polymeric nanoparticle (PNP) systems as a pharmaceutical approach for poorly soluble drugs, peptide drugs, gene and antibodies. Now, the products based on the PNP technologies are used in the fields of medical science, pharmaceutical science, tissue engineering and clothing, food and housing. This review focuses attention on PNPs for specific enhanced and targeted drug delivery of therapeutic drugs including peptide drugs as well as drug delivery applications of such systems. Outcomes from recent studies on polymers, how to make PNPs, pharmacokinetics and pharmacodynamics of PNPs, and the release profiles from PNPs and related systems are also described, including their pharmacokinetics and pharmacodynamics, if available. In addition, the latest PNP trends and will be described.