Sustained release of PTH(1-34) from PLGA microspheres suppresses osteoarthritis progression in rats

A combination of chitosan nanoparticles loaded with celecoxib and kartogenin has anti-inflammatory and chondroprotective effects: Results from an in vitro model of osteoarthritis

Loading drugs in drug delivery systems can increase their retention time and control their release within the knee cavity. Hence, we aimed to improve the therapeutic efficacy of celecoxib and kartogenin (KGN) through their loading in chitosan nanoparticles (CS NPs). Celecoxib-loaded nanoparticles (CNPs) and KGN-loaded nanoparticles (K-CS NPs) were prepared using the absorption method and covalent attachment, respectively, through an ionic gelation process. The morphology, particle size, zeta potential, polydispersity index (PDI), conjugation efficiency (CE), encapsulation efficiency (EE), the in vitro release of the drug from NPs, as well as MTT and hemolysis assays, were evaluated. Then, the IL-1β-stimulated chondrocytes were treated with CNPs and K-CS NPs, individually or in combination, to explore their potential chondroprotective and anti-inflammatory effects. CNPs and K-CS NPs showed sizes of 352.6 ± 22.5 and 232.7 ± 4.5 nm, respectively, suitable for intra-articular (IA) injection. Based on the hemolysis results, both NPs exhibited good hemocompatibility within the studied range. Results showed that treating IL-1β-pretreated chondrocytes with CNPs or K-CS NPs remarkably limited the negative effects of IL-1β, especially when both types of NPs were used together. Therefore, injecting these two NPs into the knee cavity may improve drug bioavailability, rapidly suppress inflammation and pain, and promote cartilage regeneration. Meanwhile, for the first time, the study investigated the effect of the simultaneous use of celecoxib and KGN to treat osteoarthritis (OA).

Local injection of abaloparatide promotes mandibular condyle lengthening in adolescent rats via enhancing chondrogenesis and ossification

BACKGROUND

Mandibular condylar hypoplasia negatively affects patient's facial appearance and dentofacial function.

OBJECTIVE

To investigate the effect of local injection of the drug abaloparatide (ABL), an analogue of parathyroid hormone related protein (PTHrP), on promoting lengthening of the mandibular condyle.

METHODS

Thirty adolescent male Sprague-Dawley rats were randomly divided into two groups, which received the injection of ABL or normal saline (the control) every 3 days in the temporomandibular joint (TMJ) cavity. Cone-beam computed tomography and immunohistochemistry assays were performed at 2, 4 and 6 weeks since the injection. Mandibular condylar chondrocytes (MCC) and pre-osteoblasts were treated with ABL or PBS, followed by the CCK-8 detection, IC50, real-time PCR assay, Western Blot and immunofluorescence staining.

RESULTS

In vivo, compared with the control, the ABL group significantly increased the mandibular condylar process length (by 1.34 ± 0.59 mm at 6 weeks), the thickness of the cartilage layer, and enhanced the matrix synthesis. The ABL group had significant up-regulation of SOX 9, COL II, PTHrP and PTH1R, down-regulation of COL X in the cartilage, up-regulation of RUNX 2, and unchanged osteoclastogenesis in the subchondral bone. In vitro, the intra-TMJ injection of ABL promoted the MCC proliferation, with up-regulated expression of chondrogenic genes, and enhanced osteogenic differentiation of the pre-osteoblasts.

CONCLUSIONS

Intra-TMJ injection of abaloparatide promotes mandibular condyle lengthening in the adolescent rats via enhancing chondrogenesis in the mandibular condylar cartilage and ossification in the subchondral bone.

A personalized biomimetic dual-drug delivery system via controlled release of PTH1-34 and simvastatin for in situ osteoporotic bone regeneration

Patients with osteoporosis often encounter clinical challenges of poor healing after bone transplantation due to their diminished bone formation capacity. The use of bone substitutes containing bioactive factors that increase the number and differentiation of osteoblasts is a strategy to improve poor bone healing. In this study, we developed an in situ dual-drug delivery system containing the bone growth factors PTH1-34 and simvastatin to increase the number and differentiation of osteoblasts for osteoporotic bone regeneration. Our system exhibited ideal physical properties similar to those of natural bone and allowed for customizations in shape through a 3D-printed scaffold and GelMA. The composite system regulated the sustained release of PTH1-34 and simvastatin, and exhibited good biocompatibility. Cell studies revealed that the composite system reduced osteoblast death, and promoted expression of osteoblast differentiation markers. Additionally, by radiographic analysis and histological observation, the dual-drug composite system demonstrated promising bone regeneration outcomes in an osteoporotic skull defect model. In summary, this composite delivery system, comprising dual-drug administration, holds considerable potential for bone repair and may serve as a safe and efficacious therapeutic approach for addressing bone defects in patients with osteoporosis.

Microscale strain concentrations in tissue-engineered osteochondral implants are dictated by local compositional thresholds and architecture

Tissue-engineered osteochondral implants manufactured from condensed mesenchymal stem cell bodies have shown promise for treating focal cartilage defects. Notably, such manufacturing techniques have shown to successfully recapture the bulk mechanical properties of native cartilage. However, the relationships among the architectural features, local composition, and micromechanical environment within tissue-engineered cartilage from cell-based aggregates remain unclear. Understanding such relationships is crucial for identifying critical parameters that can predict in vivo performance. Therefore, this study investigated the relationship among architectural features, composition, and micromechanical behavior of tissue-engineered osteochondral implants. We utilized fast-confocal microscopy combined with a strain mapping technique to analyze the micromechanical behavior under quasi-static loading, as well as Fourier Transform Infrared Spectroscopy to analyze the local compositions. More specifically, we investigated the architectural features and compositional distributions generated from tissue maturation, along with macro- and micro-level strain distributions. Our results showed that under compression, cell-based aggregates underwent deformation followed by body movement, generating high local strain around the boundaries, where local aggrecan concentration was low and local collagen concentration was high. By analyzing the micromechanics and composition at the single aggregate length scale, we identified a strong threshold relationship between local strain and compositions. Namely at the aggrecan concentration below 0.015 arbitrary unit (A.U.) and the collagen concentration above 0.15 A.U., the constructs experienced greater than threefold increase in compressive strain. Overall, this study suggests that local compositional features are the primary driver of the local mechanical environment in tissue-engineered cartilage constructs, providing insight into potential quality control parameters for manufacturing tissue-engineered constructs.

Hydroxyapatite Incorporated with Fe3O4@MCM-41 Core-Shell: A Promising Nanocomposite for Teriparatide Delivery in Bone Tissue Regeneration

This article presents a comprehensive study of the development of a novel nanocomposite comprising core-shell Fe3O4@MCM-41 with superparamagnetic properties and hydroxyapatite (HAp). The nanocomposite serves as a pH-responsive nanocarrier, offering an efficient injectable dosage for teriparatide (PTH (1-34)) delivery. The aim is to address the limitations associated with drug-induced side effects, precautionary measures, and frequent injections. The nanocomposites, as prepared, were characterized using techniques including X-ray diffraction, Fourier transform infrared, zeta potential, dynamic light scattering, VSM, scanning electron microscopy, and transmission electron microscopy. The nanocomposites' average crystallite diameter was determined to be 27 ± 5 nm. The hydrodynamic size of the PTH (1-34)-loaded nanocarrier ranged from 357 to 495 nm, with a surface charge of -33 mV. The entrapment and loading efficiencies were determined to be 73% and 31%, respectively. All of these findings collectively affirm successful fabrication. Additionally, in vivo medication delivery was investigated using the HPLC method, mirroring the in vitro tests. Utilizing the dialysis approach, we demonstrated sustained-release behavior. PTH (1-34) diffusion increased as the pH decreased from 7.4 to 5.6. After 24 h, drug release was higher at acidic pH (88%) compared to normal pH (43%). The biocompatibility of the PTH (1-34)-loaded nanocarrier was assessed using the MTT assay employing the NIH3T3 and HEK-293 cell lines. The results demonstrated that the nanocarrier not only exhibited nontoxicity but also promoted cell proliferation and differentiation. In the in vivo test, the drug concentration reached 505 μg within 30 min of exposure to the magnetic field. Based on these findings, the Fe3O4@MCM-41/HAp/PTH (1-34) nanocomposite, in combination with a magnetic field, offers an efficient and biocompatible approach to enhance the therapeutic effect of osteogenesis and overcome drug limitations.

Formulation and evaluation of Ocimum sanctum Linn containing carboxymethylcellulose and sorbitol based hydrogel

It is of interest to formulate a hydrogel consisting of Ocimum sanctum Linn, sorbitol, and carboxymethyl cellulose and to evaluate the physical properties of the hydrogel. The hydrogel was prepared by dissolving Ocimum sanctum Linn extract into the mixture containing sorbitol and carboxymethyl cellulose. The formulation was further evaluated for its swelling index, contact angle, in -vitro release properties, and surface analysis using atomic force microscopy. The swelling index showed a significant increase in weight from 1st hr to the 84th hour which is 11.1% and 15.8% respectively. The contact angle test showed a value of 72.81° and 75.99° respectively. In vitro drug release showed a burst release till the 6th day followed by a sustained release till the 20th day. Atomic force microscopy revealed smooth and consistent surface topography with a mean size of 51µm in diameter which depicts that the particles are well dispersed throughout the hydrogel matrix. Data show that hydrogel containing Ocimum sanctum Linn extract, sorbitol, and carboxymethyl cellulose could be an efficient economic primeval substitute that is non-toxic, natural, and structured for clinical application.

Injectable hydrogel loaded with bilayer microspheres to inhibit angiogenesis and promote cartilage regeneration for repairing growth plate injury

Introduction: The repair and regeneration of growth plate injuries using tissue engineering techniques remains a challenge due to large bone bridge formation and low chondrogenic efficiency. Methods: In this study, a bilayer drug-loaded microspheres was developed that contains the vascular endothelial growth factor (VEGF) inhibitor, Bevacizumab, on the outer layer and insulin-like growth factor-1 (IGF-1), a cartilage repair factor, on the inner layer. The microspheres were then combined with bone marrow mesenchymal stem cells (BMSCs) in the gelatin methacryloyl (GelMA) hydrogel to create a composite hydrogel with good injectability and biocompatibility. Results: The in vitro drug-release profile of bilayer microspheres showed a sequential release, with Bevacizumab released first followed by IGF-1. And this hydrogel simultaneously inhibited angiogenesis and promoted cartilage regeneration. Finally, in vivo studies indicated that the composite hydrogel reduced bone bridge formation and improved cartilage regeneration in the rabbit model of proximal tibial growth plate injury. Conclusion: This bilayer microsphere-based composite hydrogel with sequential controlled release of Bevacizumab and IGF-1 has promising potential for growth plate injury repair.

Graphene Oxide/RhPTH(1-34)/Polylactide Composite Nanofibrous Scaffold for Bone Tissue Engineering

Polylactide (PLA) is one of the most promising polymers that has been widely used for the repair of damaged tissues due to its biocompatibility and biodegradability. PLA composites with multiple properties, such as mechanical properties and osteogenesis, have been widely investigated. Herein, PLA/graphene oxide (GO)/parathyroid hormone (rhPTH(1-34)) nanofiber membranes were prepared using a solution electrospinning method. The tensile strength of the PLA/GO/rhPTH(1-34) membranes was 2.64 MPa, nearly 110% higher than that of a pure PLA sample (1.26 MPa). The biocompatibility and osteogenic differentiation test demonstrated that the addition of GO did not markedly affect the biocompatibility of PLA, and the alkaline phosphatase activity of PLA/GO/rhPTH(1-34) membranes was about 2.3-times that of PLA. These results imply that the PLA/GO/rhPTH(1-34) composite membrane may be a candidate material for bone tissue engineering.

New insights in osteoarthritis diagnosis and treatment: Nano-strategies for an improved disease management

Osteoarthritis (OA) is a common chronic joint pathology that has become a predominant cause of disability worldwide. Even though the origin and evolution of OA rely on different factors that are not yet elucidated nor understood, the development of novel strategies to treat OA has emerged in the last years. Cartilage degradation is the main hallmark of the pathology though alterations in bone and synovial inflammation, among other comorbidities, are also involved during OA progression. From a molecular point of view, a vast amount of signaling pathways are implicated in the progression of the disease, opening up a wide plethora of targets to attenuate or even halt OA. The main purpose of this review is to shed light on the recent strategies published based on nanotechnology for the early diagnosis of the disease as well as the most promising nano-enabling therapeutic approaches validated in preclinical models. To address the clinical issue, the key pathways involved in OA initiation and progression are described as the main potential targets for OA prevention and early treatment. Furthermore, an overview of current therapeutic strategies is depicted. Finally, to solve the drawbacks of current treatments, nanobiomedicine has shown demonstrated benefits when using drug delivery systems compared with the administration of the equivalent doses of the free drugs and the potential of disease-modifying OA drugs when using nanosystems. We anticipate that the development of smart and specific bioresponsive and biocompatible nanosystems will provide a solid and promising basis for effective OA early diagnosis and treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

Evaluation of the Effects of Gamma Radiation Sterilization on Rhein-Loaded Biodegradable Microparticles for the Treatment of Osteoarthritis

In previous work, we reported on the design of biodegradable rhein-loaded PLGA microparticles for the treatment of osteoarthritis. Considering that a formulation designed for intra-articular administration must meet sterility requirements to guarantee its safety, in this study the effect of gamma radiation sterilization on these microparticles was evaluated. The size, morphology, and surface characteristics of the microparticles and the encapsulation efficiency of rhein were not affected by the sterilization process. Although DSC and PXRD analyses suggested otherwise, rhein release profiles were not altered by gamma radiation. The release of rhein from the microparticles was fitted to a Gompertz model. In conclusion, the results of this study suggest that gamma radiation is a suitable method for the sterilization of rhein-loaded PLGA microparticles to enable their intra-articular administration in order to provide a therapeutic solution to patients suffering from chronic joint diseases.

Potential effects of teriparatide (PTH (1-34)) on osteoarthritis: a systematic review

Osteoarthritis (OA) is a common and prevalent degenerative joint disease characterized by degradation of the articular cartilage. However, none of disease-modifying OA drugs is approved currently. Teriparatide (PTH (1-34)) might stimulate chondrocyte proliferation and cartilage regeneration via some uncertain mechanisms. Relevant therapies of PTH (1-34) on OA with such effects have recently gained increasing interest, but have not become widespread practice. Thus, we launch this systematic review (SR) to update the latest evidence accordingly. A comprehensive literature search was conducted in PubMed, Web of Science, MEDLINE, the Cochrane Library, and Embase from their inception to February 2022. Studies investigating the effects of the PTH (1-34) on OA were obtained. The quality assessment and descriptive summary were made of all included studies. Overall, 307 records were identified, and 33 studies were included. In vivo studies (n = 22) concluded that PTH (1-34) slowed progression of OA by alleviating cartilage degeneration and aberrant remodeling of subchondral bone (SCB). Moreover, PTH (1-34) exhibited repair of cartilage and SCB, analgesic, and anti-inflammatory effects. In vitro studies (n = 11) concluded that PTH (1-34) was important for chondrocytes via increasing the proliferation and matrix synthesis but preventing apoptosis or hypertrophy. All included studies were assessed with low or unclear risk of bias in methodological quality. The SR demonstrated that PTH (1-34) could alleviate the progression of OA. Moreover, PTH (1-34) had beneficial effects on osteoporotic OA (OPOA) models, which might be a therapeutic option for OA and OPOA treatment.

Teriparatide prevented synovial inflammation and cartilage destruction in mice with DMM

AIM

Emerging data have demonstrated that low-grade inflammation in osteoarthritis, a long-held degenerative disease. The inflamed synovium produces various cytokines that induce cartilage destruction and joint pain. A previous study showed that teriparatide, an FDA approved anti-osteoporotic drug, may enhance cartilage repair. Our study focuses on its role in OA synovitis.

MATERIALS AND METHODS

Primary mouse articular chondrocytes were used to determine the most potent cytokines involved in OA inflammation and cartilage destruction. A destabilization of the medial meniscus mouse model was established to investigate the effect of teriparatide in OA, particularly, on synovial inflammation and cartilage degradation.

RESULTS

In vitro experiments showed that TNF-α was the most potent inducer of cartilage matrix-degrading enzymes, and that teriparatide antagonized the TNF-α of effect. Consistently, articular cartilage samples from TNF-α transgenic mice contained more MMP-13 positive chondrocytes than those from wild type mice. In addition, more type II collagen was cleaved in human OA cartilage than in normal cartilage samples.

CONCLUSIONS

Teriparatide can prevent synovitis and cartilage degradation by suppressing TNF-α mediated MMP-13 overexpression. Together with its chondroregenerative capability, teriparatide may be the first effective disease modifying osteoarthritis drug.

Applications and prospects of intra-articular drug delivery system in arthritis therapeutics

Arthritis is a kind of chronic disease that affects joints and muscles with the symptoms of joint pain, inflammation and limited movement of joints. Among various clinical therapies, drug therapy has been extensively applied because of its accessibility, safety and effectiveness. In recent years, the intra-articular injection has dramatic therapeutic effects in treating arthritis with high patient compliance and low side effects. In this review, we will introduce pathology of arthritis, along with the accessible treatment and diagnosis methods, then we will summarize major advances of current hopeful intra-articular delivery systems such as microspheres, hydrogels, nanoparticles and liposomes. At last, some safety assessments in the preclinical work and the main challenges for the further development of intra-articular treatment were also discussed.

Anabolic Peptide-Enriched Stealth Nanoliposomes for Effective Anti-Osteoporotic Therapy

The objective of the present work was to develop PTH (1-34)-loaded stealth nanoliposomes (PTH-LPs) by employing the use of the Quality by Design (QbD) approach. Risk identification was carried out using the Ishikawa fishbone diagram. PTH-LPs were optimized using Box Behnken Design, a type of response surface methodology to examine the effect of independent variables on dependent variables such as particle size and percentage entrapment efficiency (%EE). Design space was generated for PTH-LPs to reduce interbatch variability during the formulation development process. Furthermore, a cytotoxicity assay, cell proliferation assay, calcium calorimetric assay, mineralized nodule formation, and cellular uptake assay were carried out on MG-63 osteoblast-like cells. The results obtained from these procedures demonstrated that lipid concentration had a significant positive impact on particle size and %EE, whereas cholesterol concentration showed a reduction in %EE. The particle size and %EE of optimized formulation were found to be 147.76 ± 2.14 nm and 69.18 ± 3.62%, respectively. Optimized PTH-LPs showed the sustained release profile of the drug. In vitro cell evaluation studies showed PTH-LPs have good biocompatibility with MG-63 cells. The cell proliferation study revealed that PTH-LPs induced osteoblast differentiation which improved the formation of mineralized nodules in MG-63 cells. The outcome of the present study conclusively demonstrated the potential of the QbD concept to build quality in PTH-LPs with improved osteoanabolic therapy in osteoporosis.

Alternative Routes of Administration for Therapeutic Antibodies—State of the Art

Background: For the past two decades, there has been a huge expansion in the development of therapeutic antibodies, with 6 to 10 novel entities approved each year. Around 70% of these Abs are delivered through IV injection, a mode of administration allowing rapid and systemic delivery of the drug. However, according to the evidence presented in the literature, beyond the reduction of invasiveness, a better efficacy can be achieved with local delivery. Consequently, efforts have been made toward the development of innovative methods of administration, and in the formulation and engineering of novel Abs to improve their therapeutic index. Objective: This review presents an overview of the routes of administration used to deliver Abs, different from the IV route, whether approved or in the clinical evaluation stage. We provide a description of the physical and biological fundamentals for each route of administration, highlighting their relevance with examples of clinically-relevant Abs, and discussing their strengths and limitations. Methods: We reviewed and analyzed the current literature, published as of the 1 April 2022 using MEDLINE and EMBASE databases, as well as the FDA and EMA websites. Ongoing trials were identified using clinicaltrials.gov. Publications and data were identified using a list of general keywords. Conclusions: Apart from the most commonly used IV route, topical delivery of Abs has shown clinical successes, improving drug bioavailability and efficacy while reducing side-effects. However, additional research is necessary to understand the consequences of biological barriers associated with local delivery for Ab partitioning, in order to optimize delivery methods and devices, and to adapt Ab formulation to local delivery. Novel modes of administration for Abs might in fine allow a better support to patients, especially in the context of chronic diseases, as well as a reduction of the treatment cost.

Monoporous Microsphere as a Dynamically Movable Drug Carrier for Osteoporotic Bone Remodeling

To repair systematically osteoporotic bone defects, it is significant to take effort on both the diminishment of osteoporosis and the enhancement of bone regeneration. Herein, a specifically monoporous microsphere carrier encapsulating dosage-sensitive and short half-time parathyroid hormone (PTH) has been constructed to tackle the issue. Compared with conventional microsphere carriers involving compact, porous, and mesoporous microspheres, the monoporous microsphere is desirable to achieve precisely in-situ delivery and to minimize topical accumulation. Our findings show that the PTH loaded inside MPMs can be gradually released from the single hole of MPMs to improve the initial drug concentration. Also, the MPMs can self-shift with the daily movement of experimental animals to effectively reduce the topical aggregation of released drugs in vitro. In vivo evaluation further confirms that the implant of MPMs-PTH plays a dual role in stimulating the regenerative repair of the cranial defect and relieving osteoporosis in the whole body. Consequently, our current work develops a dynamically movable drug delivery system to achieve precisely in-situ delivery, minimize topical accumulation, and systematically repair osteoporotic bone defects. This article is protected by copyright. All rights reserved.

Enhanced oral absorption of teriparatide with therapeutic potential for management of osteoporosis

In this study, a system for oral delivery of recombinant human parathyroid hormone [rhPTH(1-34); teriparatide (TRP)] was developed to enhance oral absorption and to demonstrate an equivalent therapeutic effect to that of subcutaneous (SC) TRP injection. The solid oral formulation of TRP was prepared by electrostatic complexation with l-lysine-linked deoxycholic acid (LDA) and deoxycholic acid (DA) at a molar ratio of 1:5:7 in the aqueous dispersion of non-ionic n-dodecyl-β-d-maltoside (DM) at a 1:15 weight ratio, followed by freeze-drying the dispersal, yielding TRP(1:5:7)-15. As expected, TRP(1:5:7)-15 showed a 414% increase in permeability across the Caco-2/HT29-MTX-E12 cell monolayer, resulting in a 13.0-fold greater oral bioavailability compared with free TRP. In addition, the intestinal transport mechanisms in the presence of specific inhibitors of clathrin-mediated endocytosis, macropinocytosis, and bile acid transporters revealed 44.4%, 28.7%, and 51.2% decreases in transport, respectively, confirming that these routes play crucial roles in the permeation of TRP in TRP(1:5:7)-15. Notably, this formulation showed similar activation of the release of cyclic adenosine monophosphate (cAMP) compared with TRP, suggesting equivalent efficacy in the parathyroid hormone receptor-adenylate cyclase system of osteosarcoma cells. Furthermore, oral TRP(1:5:7)-15 (equivalent to 0.4 mg/kg TRP) demonstrated increases in bone mineral density (36.9%) and trabecular thickness (31.3%) compared with untreated glucocorticoid-induced osteoporotic mice. Moreover, the elevated levels of biomarkers of bone formation, including osteocalcin, were also comparable with those after SC injection of TRP (0.02 mg/kg). These findings suggest that TRP(1:5:7)-15 can be used as an effective oral therapy for the management of osteoporosis.

Parathyroid Hormone (1-34) Attenuates Cartilage Degradation and Preserves Subchondral Bone Micro-architecture in Rats with Patella Baja-Induced-Patellofemoral Joint Osteoarthritis

Several studies have revealed that PTH1-34 may possess the potential for treating osteoarthritis (OA) and osteoporosis. However, no study has yet determined whether PTH1-34 can be used for the treatment of patella baja-induced patellofemoral joint OA (PFJOA). Thus, this study sought to assess the efficacy of PTH1-34 for the treatment of PFJOA in a rat model. Patella baja was induced in 3-month-old female Sprague-Dawley (SD) rats by patellar ligament shortening (PLS), after which the rats were randomly divided into three groups (n = 12): Sham, PLS, and PTH group (PTH + PLS, PTH1-34, 30 µg/kg/d, 5 days per week for 10 weeks). Thereafter, radiographic imaging, macroscopic and microscopic analyses, immunohistochemistry, and microcomputed tomography (CT) analysis were performed. The appearance of PLS-induced PFJOA promoted obvious changes in the patellar position and structure in the PLS group, which were characterized by cartilage degeneration, subchondral bone microstructure deterioration, patella baja, and increasing patella length. However, these negative characteristics were markedly ameliorated by PTH1-34, which not only inhibited cartilage catabolism by decreasing MMP-13 and ADAMTS-4 but also enhanced anabolism by increasing Col-II and Aggrecan. Furthermore, the micro-CT results showed a marked improvement in subchondral bone microarchitecture. The findings presented herein demonstrated that early treatment with PTH1-34 could improve cartilage metabolism and subchondral bone health in this PFJOA model.

Micro- and nanotechnology in biomedical engineering for cartilage tissue regeneration in osteoarthritis

Osteoarthritis, which typically arises from aging, traumatic injury, or obesity, is the most common form of arthritis, which usually leads to malfunction of the joints and requires medical interventions due to the poor self-healing capacity of articular cartilage. However, currently used medical treatment modalities have reported, at least in part, disappointing and frustrating results for patients with osteoarthritis. Recent progress in the design and fabrication of tissue-engineered microscale/nanoscale platforms, which arises from the convergence of stem cell research and nanotechnology methods, has shown promising results in the administration of new and efficient options for treating osteochondral lesions. This paper presents an overview of the recent advances in osteochondral tissue engineering resulting from the application of micro- and nanotechnology approaches in the structure of biomaterials, including biological and microscale/nanoscale topographical cues, microspheres, nanoparticles, nanofibers, and nanotubes.

Therapeutic antibodies - natural and pathological barriers and strategies to overcome them

Antibody-based therapeutics have become a major class of therapeutics with over 120 recombinant antibodies approved or under review in the EU or US. This therapeutic class has experienced a remarkable expansion with an expected acceleration in 2021-2022 due to the extraordinary global response to SARS-CoV2 pandemic and the public disclosure of over a hundred anti-SARS-CoV2 antibodies. Mainly delivered intravenously, alternative delivery routes have emerged to improve antibody therapeutic index and patient comfort. A major hurdle for antibody delivery and efficacy as well as the development of alternative administration routes, is to understand the different natural and pathological barriers that antibodies face as soon as they enter the body up to the moment they bind to their target antigen. In this review, we discuss the well-known and more under-investigated extracellular and cellular barriers faced by antibodies. We also discuss some of the strategies developed in the recent years to overcome these barriers and increase antibody delivery to its site of action. A better understanding of the biological barriers that antibodies have to face will allow the optimization of antibody delivery near its target. This opens the way to the development of improved therapy with less systemic side effects and increased patients' adherence to the treatment.

Carbazate-modified cross-linked dextran microparticles suppress the progression of osteoarthritis by ROS scavenging

A series of modified polysaccharide microparticles have been fabricated and their potential application for scavenging reactive oxygen species (ROS) and their derivatives to achieve osteoarthritis (OA) treatment has been explored. These microparticles were cross-linked dextran (Sephadex) with different carbazate substitution ratios determined by the TNBS assay and elemental analysis. It has been demonstrated that they could effectively scavenge carbonylated proteins and ROS including hydroxyl radicals (˙OH), superoxide anions (˙O₂^-) and H₂O₂ and their derivatives with high efficiency, improve the viability of H₂O₂-treated chondrocytes by reducing their ROS levels, as well as lower their inflammatory factors. The above ability of antioxidation and inflammation resistance improved with the increase of carbazate substitution ratio. Significantly, this work provided the proof that modified Sephadex successfully alleviated the deterioration of cartilage and the progression of OA in vivo. The proposed microparticles showed a very promising capability for reducing ROS levels and further treating OA.

Intra-articular low-dose parathyroid hormone (1-34) improves mobility and articular cartilage quality in a preclinical age-related knee osteoarthritis model

Aims

Osteoarthritis (OA) is prevalent among the elderly and incurable. Intra-articular parathyroid hormone (PTH) ameliorated OA in papain-induced and anterior cruciate ligament transection-induced OA models; therefore, we hypothesized that PTH improved OA in a preclinical age-related OA model.

Methods

Guinea pigs aged between six and seven months of age were randomized into control or treatment groups. Three- or four-month-old guinea pigs served as the young control group. The knees were administered 40 μl intra-articular injections of 10 nM PTH or vehicle once a week for three months. Their endurance as determined from time on the treadmill was evaluated before kill. Their tibial plateaus were analyzed using microcalculated tomography (μCT) and histological studies.

Results

PTH increased the endurance on the treadmill test, preserved glycosaminoglycans, and reduced Osteoarthritis Research Society International score and chondrocyte apoptosis rate. No difference was observed in the subchondral plate bone density or metaphyseal trabecular bone volume and bone morphogenetic 2 protein staining.

Conclusion

Subchondral bone is crucial in the initiation and progression of OA. Although previous studies have shown that subcutaneous PTH alleviates knee OA by improving subchondral and metaphyseal bone mass, we demonstrated that intra-articular PTH injections improved spontaneous OA by directly affecting the cartilage rather than the subchondral or metaphyseal bone in a preclinical age-related OA model.

Cite this article: Bone Joint Res 2021;10(8):514–525.

Causal Relationship Between Parathyroid Hormone and the Risk of Osteoarthritis: A Mendelian Randomization Study

Background

Previous studies have demonstrated an inverse association between parathyroid hormone (PTH) and the risk of osteoarthritis (OA). However, it remains unknown whether such association reflects causality. We aimed to apply a Mendelian randomization (MR) approach to investigate the causal association between PTH and OA.

Materials and Methods

We performed a two-sample MR analysis using summary statistics from 13 cohorts (PTH, N = 29,155) and a recent genome-wide association study meta-analysis (OA, N = 455,221) by the UK Biobank and Arthritis Research UK OA Genetics (arcOGEN). MR analyses were carried out mainly using the inverse-variance-weighted method. Sensitivity analyses were performed to test the robustness of the associations using the weighted median method, the MR-Egger method, and "leave-one-out" analysis. Analyses were performed again to test whether the associations remained statistically significant after excluding any outlier variants that were detected using the MR-PRESSO (Mendelian Randomization Pleiotropy RESidual Sum and Outlier) test.

Results

Five single-nucleotide polymorphisms (SNPs) were selected as instrumental variables at the genome-wide significance threshold (p < 5 × 10^-8). The causal effect between PTH and OA was genetically predicted using the inverse-variance-weighted method (odds ratio = 0.67, 95% confidence interval: 0.50-0.90; p = 0.008). This result was borne out using the weighted median method (odds ratio = 0.73, 95% confidence interval: 0.60-0.90; p = 0.004). The causality remained robust after discarding the outlier variants as well as SNPs associated with confounding factors.

Conclusion

MR analysis supported a potential causative relationship between decreased serum circulating PTH and a higher risk of hip and knee OA.

3D bio-printed biphasic scaffolds with dual modification of silk fibroin for the integrated repair of osteochondral defects

Repair of osteochondral defects is still a challenge, especially the regeneration of hyaline cartilage. Parathyroid hormone (PTH) can inhibit the hypertrophy of chondrocytes to maintain the phenotype of hyaline cartilage. Here, we aimed to construct a bio-printed biphasic scaffold with a mechanical gradient based on dual modification of silk fibroin (SF) for the integrated repair of osteochondral defects. Briefly, SF was grafted with PTH (SF-PTH) and covalently immobilized with methacrylic anhydride (SF-MA), respectively. Next, gelatin methacryloyl (GM) mixed with SF-PTH or SF-MA was used as a bio-ink for articular cartilage and subchondral bone regeneration. Finally, the GM + SF-PTH/GM + SF-MA osteochondral biphasic scaffold was constructed using 3D bioprinting technology, and implanted in a rabbit osteochondral defect model. In this study, the SF-PTH bio-ink was synthesized for the first time. In vitro results indicated that the GM + SF-MA bio-ink had good mechanical properties, while the GM + SF-PTH bio-ink inhibited the hypertrophy of chondrocytes and was beneficial for the production of hyaline cartilage extracellular matrix. Importantly, an integrated GM + SF-PTH/GM + SF-MA biphasic scaffold with a mechanical gradient was successfully constructed. The results in vivo demonstrated that the GM + SF-PTH/GM + SF-MA scaffold could promote the regeneration of osteochondral defects and maintain the phenotype of hyaline cartilage to a large extent. Collectively, our results indicate that the integrated GM + SF-PTH/GM + SF-MA biphasic scaffold constructed by 3D bioprinting is expected to become a new strategy for the treatment of osteochondral defects.

Recent developments in natural and synthetic polymeric drug delivery systems used for the treatment of osteoarthritis

Osteoarthritis (OA), is a common musculoskeletal disorder that will progressively increase in older populations and is expected to be the most dominant cause of disability in the world population by 2030. The progression of OA is controlled by a multi-factorial pathway that has not been completely elucidated and understood yet. However, over the years, research efforts have provided a significant understanding of some of the processes contributing to the progression of OA. Both cartilage and bone degradation processes induce articular cells to produce inflammatory mediators that produce proinflammatory cytokines that block the synthesis of collagen type II and aggrecan, the major components of cartilage. Systemic administration and intraarticular injection of anti-inflammatory agents are the first-line treatments of OA. However, small anti-inflammatory molecules are rapidly cleared from the joint cavity which limits their therapeutic efficacy. To palliate this strong technological drawback, different types of polymeric materials such as microparticles, nanoparticles, and hydrogels, have been examined as drug carriers for the delivery of therapeutic agents to articular joints. The main purpose of this review is to provide a summary of recent developments in natural and synthetic polymeric drug delivery systems for the delivery of anti-inflammatory agents to arthritic joints. Furthermore, this review provides an overview of the design rules that have been proposed so far for the development of drug carriers used in OA therapy. Overall it is difficult to state clearly which polymeric platform is the most efficient one because many advantages and disadvantages could be pointed to both natural and synthetic formulations. That requires further research in the near future.

Parathyroid hormone attenuates osteoarthritis pain by remodeling subchondral bone in mice

Osteoarthritis, a highly prevalent degenerative joint disorder, is characterized by joint pain and disability. Available treatments fail to modify osteoarthritis progression and decrease joint pain effectively. Here, we show that intermittent parathyroid hormone (iPTH) attenuates osteoarthritis pain by inhibiting subchondral sensory innervation, subchondral bone deterioration, and articular cartilage degeneration in a destabilized medial meniscus (DMM) mouse model. We found that subchondral sensory innervation for osteoarthritis pain was significantly decreased in PTH-treated DMM mice compared with vehicle-treated DMM mice. In parallel, deterioration of subchondral bone microarchitecture in DMM mice was attenuated by iPTH treatment. Increased level of prostaglandin E2 in subchondral bone of DMM mice was reduced by iPTH treatment. Furthermore, uncoupled subchondral bone remodeling caused by increased transforming growth factor β signaling was regulated by PTH-induced endocytosis of the PTH type 1 receptor-transforming growth factor β type 2 receptor complex. Notably, iPTH improved subchondral bone microarchitecture and decreased level of prostaglandin E2 and sensory innervation of subchondral bone in DMM mice by acting specifically through PTH type 1 receptor in Nestin+ mesenchymal stromal cells. Thus, iPTH could be a potential disease-modifying therapy for osteoarthritis.

PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression in MIO mice

This study aims to investigate the effects and mechanisms of parathyroid hormone [1-34] (PTH1-34) on TNF-α-stimulated mice chondrocytes, as well as cartilage from a meniscus injury induced osteoarthritis (MIO) mice model. The C57BL/6J mice received medial meniscectomy, and then administrated with PTH1-34. The results showed that PTH1-34 administration decreased secondary allodynia and the pain-related transcripts. The IHC, ELISA, Micro-CT imaging and histopathology analysis revealed the significantly improved subchondral plate thickness and bone porosity, the reduced pro-inflammatory cytokines in serum and joint fluid. In vitro, mice chondrocyte was treated with TNF-α or co-cultured with synovial cells. The results showed that TNF-α markedly upregulated the MMP13 expression, and the ERK1/2, NF-κB or PI3K signaling pathway inhibitors could reverse the induction effect of TNF-α on expression of MMP13 in chondrocytes. PTH1-34 alone has no effect on the expression of MMP13 and NF-κB signaling pathways, but the PTH1-34 could reverse the induction effect of TNF-α on MMP13 expression and NF-κB signaling pathway activation in chondrocytes. In addition, PTH1-34 administration inhibited the expression of TNF-α and MMP13, and chondrocyte viability, while the PKA repressor reversed the effect of PTH1-34 in chondrocytes co-cultured with synovial cells. In conclusion, PTH1-34 has an obvious analgesic and anti-inflammatory effect, inhibits the matrix synthesis and alleviates the progression of osteoarthritis. In vitro, PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression via the PKA pathway and the NF-κB signaling pathways, respectively.

"Old Drugs, New Tricks" - Local controlled drug release systems for treatment of degenerative joint disease

Osteoarthritis (OA) and chronic low back pain (CLBP) caused by intervertebral disc (IVD) degeneration are joint diseases that have become major causes for loss of quality of life worldwide. Despite the unmet need, effective treatments other than invasive, and often ineffective, surgery are lacking. Systemic administration of drugs entails suboptimal local drug exposure in the articular joint and IVD. This review provides an overview of the potency of biomaterial-based drug delivery systems as novel treatment modality, with a focus on the biological effects of drug release systems that have reached translation at the level of in vivo models and relevant ex vivo models. These studies have shown encouraging results of biomaterial-based local delivery of several types of drugs, mostly inhibitors of inflammatory cytokines or other degenerative factors. Prevention of inflammation and degeneration and pain relief was achieved, although mainly in small animal models, with interventions applied at an early disease stage. Less convincing data were obtained with the delivery of regenerative factors. Multidisciplinary efforts towards tackling the discord between in vitro and in vivo release, combined with adaptations in the regulatory landscape may be needed to enhance safe and expeditious introduction of more and more effective controlled release-based treatments with the OA and CLBP patients.

Biomaterial-engineered intra-articular drug delivery systems for osteoarthritis therapy

Osteoarthritis (OA) is a progressive and degenerative disease, which is no longer confined to the elderly. So far, current treatments are limited to symptom relief, and no valid OA disease-modifying drugs are available. Additionally, OA relative joint is challenging for drug delivery, since the drugs experience rapid clearance in joint, showing a poor bioavailability. Existing therapeutic drugs, like non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, are not conducive for long-term use due to adverse effects. Though supplementations, including chondroitin sulfate and glucosamine, have shown beneficial effects on joint tissues in OA, their therapeutic use is still debatable. New emerging agents, like Kartogenin (KGN) and Interleukin-1 receptor antagonist (IL-1 ra), without a proper formulation, still will not work. Therefore, it is urgent to establish a suitable and efficient drug delivery system for OA therapy. In this review, we pay attention to various types of drug delivery systems and potential therapeutic drugs that may escalate OA treatments.

Cartilage-targeting and dual MMP-13/pH responsive theranostic nanoprobes for osteoarthritis imaging and precision therapy

Osteoarthritis (OA) microenvironment is marked by matrix metalloproteinases-13 (MMP-13) overexpression and weak acidity, making it possible to develop dual-stimuli responsive theranostic nanoprobes for OA diagnosis and therapy. However, current MMP/pH-responsive systems are not suitable for OA because of their poor biocompatibility, poor degradation and non-cartilage-targeting of the responsive probes. Here we designed a novel biocompatible cartilage-targeting and MMP-13/pH-responsive ferritin nanocages (CMFn) loaded with an anti-inflammatory drug (Hydroxychloroquine, HCQ), termed CMFn@HCQ, for OA imaging and therapy. We found that CMFn could be smartly "turned on" to emit light for OA imaging in response to the level of overexpressed MMP-13 in OA microenvironment, corresponding to the degree of OA severity. Thus the light intensity detected reflected the degree of OA severity, enabling the precise disease classification by our CMFn. CMFn could be "turned off" to stop emitting light in the normal joint. CMFn@HCQ nanocages could target the cartilage and release HCQ in the OA joint specifically under acidic pH conditions in a sustained manner, prolonging the drug retention time to 14 days to remarkably reduce synovial inflammation in the OA joints. The CMFn@HCQ nanocages represent a smart dual-stimuli responsive and cartilage-targeting nanoprobes, and hold promise for imaging-guided precision therapy for OA.

PTH decreases in vitro human cartilage regeneration without affecting hypertrophic differentiation

Regenerated cartilage formed after Autologous Chondrocyte Implantation may be of suboptimal quality due to postulated hypertrophic changes. Parathyroid hormone-related peptide, containing the parathyroid hormone sequence (PTHrP 1–34), enhances cartilage growth during development and inhibits hypertrophic differentiation of mesenchymal stromal cells (MSCs) and growth plate chondrocytes. This study aims to determine the possible anabolic and/or hypertrophic effect of PTH on human articular chondrocytes. Healthy human articular cartilage-derived chondrocytes (n = 6 donors) were cultured on type II collagen-coated transwells with/without 0.1 or 1.0 μM PTH from day 0, 9, or 21 until the end of culture (day 28). Extracellular matrix production, (pre)hypertrophy and PTH signaling were assessed by RT-qPCR and/or immunohistochemistry for collagen type I, II, X, RUNX2, MMP13, PTHR1 and IHH and by determining glycosaminoglycan production and DNA content. The Bern score assessed cartilage quality by histology. Regardless of the concentration and initiation of supplementation, PTH treatment significantly decreased DNA and glycosaminoglycan content and reduced the Bern score compared with controls. Type I collagen deposition was increased, whereas PTHR1 expression and type II collagen deposition were decreased by PTH supplementation. Expression of the (pre)hypertrophic markers MMP13, RUNX2, IHH and type X collagen were not affected by PTH. In conclusion, PTH supplementation to healthy human articular chondrocytes did not affect hypertrophic differentiation, but negatively influenced cartilage quality, the tissues’ extracellular matrix and cell content. Although PTH may be an effective inhibitor of hypertrophic differentiation in MSC-based cartilage repair, care may be warranted in applying accessory PTH treatment due to its effects on articular chondrocytes.

Recent Insights into the Contribution of the Changing Hypertrophic Chondrocyte Phenotype in the Development and Progression of Osteoarthritis

Osteoarthritis (OA) is an extremely prevalent age-related condition. The economic and societal burden due to the cost of symptomatic treatment, inability to work, joint replacement, and rehabilitation is huge and increasing. Currently, there are no effective medical therapies that delay or reverse the pathological manifestations of OA. Current treatment options are, without exception, focused on slowing down progression of the disease to postpone total joint replacement surgery for as long as possible and keeping the associated pain and joint immobility manageable. Alterations in the articular cartilage chondrocyte phenotype might be fundamental in the pathological mechanisms of OA development. In many ways, the changing chondrocyte phenotype in osteoarthritic cartilage resembles the process of endochondral ossification as seen, for instance, in developing growth plates. However, the relative contribution of endochondral ossification to the changing chondrocyte phenotype in the development and progression of OA remains poorly described. In this review, we will discuss the current knowledge regarding the cartilage endochondral phenotypic changes occurring during OA development and progression, as well as the molecular and environmental effectors driving these changes. Understanding how these molecular mechanisms determine the chondrocyte cell fate in OA will be essential in enabling cartilage regenerative approaches in future treatments of OA.

Chondrocyte affinity peptide modified PAMAM conjugate as a nanoplatform for targeting and retention in cartilage

AIM

To develop a nanocarrier for targeted delivery of agents to the cartilage.

MATERIALS & METHODS

Chondrocyte affinity peptide modified PEGylated polyamidoamine conjugates (CAP-PEG-PAMAM) were prepared and rhodamine B isothiocyanate (RB) fluorophore was linked on them for comparative biological tracing and profiling.

RESULTS

CAP4-PP-RB exhibited much more efficient cellular uptake in vitro than that of PEG-PAMAM-RB. Both the conjugates were likely internalized by chondrocytes via clathrin and caveolin co-mediated endocytosis, and delivered to lysosomes. In vivo imaging demonstrated the fluorescein-labeled nanocarrier was capable to persist in the joint cavity of rats for a prolonged time. Furthermore, the CAP4-PEG-PAMAM showed a good biocompatibility and enhanced penetration effects in vivo.

CONCLUSION

CAP-PEG-PAMAM could be an effective nanocarrier for intra-articular delivery of agents to cartilage.

Microspheres containing decellularized cartilage induce chondrogenesis in vitro and remain functional after incorporation within a poly(caprolactone) filament useful for fabricating a 3D scaffold

In this study, articular cartilage was decellularized preserving a majority of the inherent proteins, cytokines, growth factors and sGAGs. The decellularized cartilage matrix (dCM) was then encapsulated in poly(lactic acid) microspheres (MS + dCM) via double emulsion. Blank microspheres without dCM, MS(-), were also produced. The microspheres were spherical in shape and protein encapsulation efficiency within MS + dCM was 63.4%. The sustained release of proteins from MS + dCM was observed over 4 weeks in vitro. Both MS + dCM and MS(-) were cytocompatible. The sustained delivery of retained growth factors and cytokines from MS + dCM promoted cell migration in contrast to MS(-). Subsequently, chondrogenesis of human mesenchymal stem cells was upregulated in presence of MS + dCM as evidenced from immunohistochemistry, biochemical quantification and qPCR studies. Specifically, collagen II, aggrecan and SOX 9 gene expression were increased in the presence of MS + dCM by an order or more in magnitude compared to MS(-) with concomitant downregulation of hypertrophic genes (COL X) despite being cultured in the absence of chondrogenic media, (p < 0.05). Lastly, microspheres containing alkaline phosphatase (MS + ALP), a surrogate to assess the thermal stability of dCM proteins, incorporated within poly(caprolactone) filaments showed that the enzyme remained functional after filament production by melt extrusion. The establishment of a novel, thermally stable process for producing filaments containing chondroinductive microspheres provides evidence supporting subsequent development of a clinically-relevant, 3D scaffold fabricated from them for osteochondral regeneration and repair.

Intra-articular delivery of tetramethylpyrazine microspheres with enhanced articular cavity retention for treating osteoarthritis

Tetramethylpyrazine (TMP) is a traditional Chinese herbal medicine with strong anti-inflammatory and cartilage protection activities, and thus a promising candidate for treating osteoarthritis. However, TMP is rapidly cleared from the joint cavity after intra-articular injection and requires multiple injections to maintain efficacy. The aim of this study was to encapsulate TMP into poly (lactic-co-glycolic acid) (PLGA) microspheres to enhance the TMP retention in the joint, reducing injection frequencies and decreasing dosage. TMP microspheres were prepared by emulsion/solvent evaporation method. The intra-articular retention of the drug was assessed by detecting the drug concentration distributed in the joint tissue at different time points. The therapeutic effect of TMP microspheres was evaluated by the swelling of knee joints and histologic analysis in papain-induced OA rat model. The prepared freeze-dried microspheres with a particle size of about 10 µm can effectively prolong the retention time of the drug in the articular cavity to 30 d, which is 4.7 times that of the TMP solution. Intra-articular injection of TMP microspheres efficiently relieved inflammatory symptoms, improved joint lesions and decreased the depletion of proteoglycan. In conclusion, intra-articular injection of TMP loaded microspheres was a promising therapeutic method in the treatment of OA.

Prolonged inhibition of inflammation in osteoarthritis by triamcinolone acetonide released from a polyester amide microsphere platform

Controlled biomaterial-based corticosteroid release might circumvent multiple injections and the accompanying risks, such as hormone imbalance and muscle weakness, in osteoarthritic (OA) patients. For this purpose, microspheres were prepared from an amino acid-based polyester amide (PEA) platform and loaded with triamcinolone acetonide (TAA). TAA loaded microspheres were shown to release TAA for over 60days in PBS. Furthermore, the bioactivity lasted at least 28days, demonstrated by a 80-95% inhibition of PGE₂ production using TNFα-stimulated chondrocyte culture, indicating inhibition of inflammation. Microspheres loaded with the near infrared marker NIR780-iodide injected in healthy rat joints or joints with mild collagenase-induced OA showed retention of the microspheres up till 70days after injection. After intra-articular injection of TAA-loaded microspheres, TAA was detectable in the serum until day seven. Synovial inflammation was significantly lower in OA joints injected with TAA-loaded microspheres based on histological Krenn scores. Injection of TAA-loaded nor empty microspheres had no effect on cartilage integrity as determined by Mankin scoring. In conclusion, the PEA platform shows safety and efficacy upon intra-articular injection, and its extended degradation and release profiles compared to the currently used PLGA platforms may render it a good alternative. Even though further in vivo studies may need to address dosing and readout parameters such as pain, no effect on cartilage pathology was found and inflammation was effectively lowered in OA joints.

Synthesis, characterization, and cytocompatibility of potential cockle shell aragonite nanocrystals for osteoporosis therapy and hormonal delivery

Calcium carbonate is a porous inorganic nanomaterial with huge potential in biomedical applications and controlled drug delivery. This study aimed at evaluating the physicochemical properties and in vitro efficacy and safety of cockle shell aragonite calcium carbonate nanocrystals (ANC) as a potential therapeutic and hormonal delivery vehicle for osteoporosis management. Free and human recombinant parathyroid hormone 1-34 (PTH 1-34)-loaded cockle shell aragonite calcium carbonate nanocrystals (PTH-ANC) were synthesized and evaluated using standard procedures. Transmission electron microscopy and field emission scanning electron microscopy results demonstrated highly homogenized spherical-shaped aragonite nanocrystals of 30±5 nm diameter. PTH-ANC had a zeta potential of -27.6±8.9 mV. The encapsulation efficiency of the formulation was found to be directly proportional to the concentrations of the drug fed. The X-ray diffraction patterns revealed strong crystallizations with no positional change of peaks before and after PTH-ANC synthesis. Fourier transform infrared spectroscopy demonstrated no detectable interactions between micron-sized aragonite and surfactant at molecular level. PTH-ANC formulation was stabilized at pH 7.5, enabling sustained slow release of PTH 1-34 for 168 h (1 week). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytocompatibility assay in Human Foetal Osteoblast Cell Line hFOB 1.19 showed that ANC can safely support osteoblast proliferation up to 48 h whereas PTH-ANC can safely support the proliferation at 72 h and beyond due to the sustained slow release of PTH 1-34. It was concluded that due to its biogenic nature, ANC is a cytocompatible antiosteoporotic agent. It doubles as a nanocarrier for the enhancement of efficacy and safety of the bone anabolic PTH 1-34. ANC is expected to reduce the cost, dosage, and dose frequency associated with the use of PTH 1-34 management of primary and secondary forms of osteoporosis.

A reformative shear precipitation procedure for the fabrication of vancomycin-loaded poly(lactide-co-glycolide) microspheres

This study reports the encapsulation of vancomycin, as a model hydrophilic drug, into poly(lactide-co-glycolide) microspheres using a novel reformative shear precipitation procedure. In contrast to the external aqueous phase used in the conventional microencapsulation technique based on emulsion solvent evaporation/extraction, the reformative shear precipitation procedure explored in this study uses a shear medium composed of glycerol as the viscous medium and ethanol as polymer antisolvent, which is relatively immiscible with the hydrophilic drug. This limits drug diffusion and leads to rapid microsphere solidification, which allows a large proportion of the hydrophilic drug to be encapsulated within the microspheres. The influence of various processing parameters, including polymer concentration, volume ratio of ethanol to glycerol in the shear medium, volume of aqueous drug solution, initial drug loading, and injecting rate of the drug-polymer emulsion, on the encapsulation efficiency and characteristics of resulting microspheres were investigated. The morphology and release characteristics, as well as mechanical, in vitro and in vivo behaviour of vancomycin-loaded poly(lactide-co-glycolide) microspheres prepared using the novel procedure were also investigated. The results demonstrated that the reformative shear precipitation procedure could achieve the loading of hydrophilic drugs into poly(lactide-co-glycolide) microspheres with high encapsulation efficiency, and the success of the procedure was largely influenced by the volume ratio of ethanol to glycerol in the shear medium. Vancomycin-loaded poly(lactide-co-glycolide) microspheres prepared using this procedure demonstrated favourable mechanical characteristics, antibacterial activity, and in vivo degradation behaviour which suggested their suitability for use as a sustained delivery system.

Orthopedic tissue regeneration: cells, scaffolds, and small molecules

Orthopedic tissue regeneration would benefit the aging population or patients with degenerative bone and cartilage diseases, especially osteoporosis and osteoarthritis. Despite progress in surgical and pharmacological interventions, new regenerative approaches are needed to meet the challenge of creating bone and articular cartilage tissues that are not only structurally sound but also functional, primarily to maintain mechanical integrity in their high load-bearing environments. In this review, we discuss new advances made in exploiting the three classes of materials in bone and cartilage regenerative medicine--cells, biomaterial-based scaffolds, and small molecules--and their successes and challenges reported in the clinic. In particular, the focus will be on the development of tissue-engineered bone and cartilage ex vivo by combining stem cells with biomaterials, providing appropriate structural, compositional, and mechanical cues to restore damaged tissue function. In addition, using small molecules to locally promote regeneration will be discussed, with potential approaches that combine bone and cartilage targeted therapeutics for the orthopedic-related disease, especially osteoporosis and osteoarthritis.

Titania nanotubes for orchestrating osteogenesis at the bone-implant interface

Titanium implants can fail due to inappropriate biomechanics at the bone-implant interface that leads to suboptimal osseointegration. Titania nanotubes (TNTs) fabricated on Ti implants by the electrochemical process have emerged as a promising modification strategy to facilitate osseointegration. TNTs enable augmentation of bone cell functions at the bone-implant interface and can be tailored to incorporate multiple functionalities including the loading of active biomolecules into the nanotubes to target anabolic processes in bone conditions such as osteoporotic fractures. Advanced functions can be introduced, including biopolymers, nanoparticles and electrical stimulation to release growth factors in a desired manner. This review describes the application of TNTs for enhancing osteogenesis at the bone-implant interface, as an alternative approach to systemic delivery of therapeutic agents.

Strategies to Optimize Adult Stem Cell Therapy for Tissue Regeneration

Stem cell therapy aims to replace damaged or aged cells with healthy functioning cells in congenital defects, tissue injuries, autoimmune disorders, and neurogenic degenerative diseases. Among various types of stem cells, adult stem cells (i.e., tissue-specific stem cells) commit to becoming the functional cells from their tissue of origin. These cells are the most commonly used in cell-based therapy since they do not confer risk of teratomas, do not require fetal stem cell maneuvers and thus are free of ethical concerns, and they confer low immunogenicity (even if allogenous). The goal of this review is to summarize the current state of the art and advances in using stem cell therapy for tissue repair in solid organs. Here we address key factors in cell preparation, such as the source of adult stem cells, optimal cell types for implantation (universal mesenchymal stem cells vs. tissue-specific stem cells, or induced vs. non-induced stem cells), early or late passages of stem cells, stem cells with endogenous or exogenous growth factors, preconditioning of stem cells (hypoxia, growth factors, or conditioned medium), using various controlled release systems to deliver growth factors with hydrogels or microspheres to provide apposite interactions of stem cells and their niche. We also review several approaches of cell delivery that affect the outcomes of cell therapy, including the appropriate routes of cell administration (systemic, intravenous, or intraperitoneal vs. local administration), timing for cell therapy (immediate vs. a few days after injury), single injection of a large number of cells vs. multiple smaller injections, a single site for injection vs. multiple sites and use of rodents vs. larger animal models. Future directions of stem cell-based therapies are also discussed to guide potential clinical applications.

PLGA-linked alendronate enhances bone repair in diaphysis defect model

Alendronate (ALN) is known as an anti-resorptive drug for the treatment of osteoporosis. Recently, ALN was found to stimulate osteogenic differentiation in mesenchymal stem cells and enhance new bone formation in calvarial bone defects. Previous in vitro and in vivo studies found that the effective concentration of ALN was approximately 1-10   μm. In the present study, a poly (lactic-co-glycolic acid) (PLGA) cross-linked ALN (PLGA-ALN) with a short-term controlled-release property for local application to enhance bone repair was developed. An in vitro drug-release kinetic test showed that PLGA-ALN microspheres released an effective concentration (50-100 nm) of ALN for 9 days. The effect of PLGA-ALN on bone repair was tested in a rat femoral bone defect model. The biomechanical study results showed that the maximal strength, stiffness and energy absorption were significantly increased in the PLGA-ALN group compared with the PLGA group. The microstructure of the newly formed bone at the defect site was analysed using microcomputed tomography. The PLGA-ALN group significantly improved the trabecular bone volume at the defect site compared with the PLGA group. The fibril collagen and immunolocalized bone morphogenetic protein 2 were evident in the newly formed trabecular bone in the PLGA-ALN group. Local use of newly developed PLGA-ALN-enhanced bone repair was attributable to increasing bone matrix formation, which improved the ultrastructure of the newly formed bone and thus increased the biomechanical properties of the repaired bone. It is suggested that PLGA-ALN may be a potential bone graft substitute to enhance bone repair. Copyright © 2016 John Wiley & Sons, Ltd.