Preclinical evaluation of (99m)Tc labeled chondroitin sulfate for monitoring of cartilage degeneration in osteoarthritis

Bone/cartilage targeted hydrogel: Strategies and applications

The skeletal system is responsible for weight-bearing, organ protection, and movement. Bone diseases caused by trauma, infection, and aging can seriously affect a patient's quality of life. Bone targeted biomaterials are suitable for the treatment of bone diseases. Biomaterials with bone-targeted properties can improve drug utilization and reduce side effects. A large number of bone-targeted micro-nano materials have been developed. However, only a few studies addressed bone-targeted hydrogel. The large size of hydrogel makes it difficult to achieve systematic targeting. However, local targeted hydrogel still has significant prospects. Molecules in bone/cartilage extracellular matrix and bone cells provide binding sites for bone-targeted hydrogel. Drug delivery systems featuring microgels with targeting properties is a key construction strategy for bone-targeted hydrogel. Besides, injectable hydrogel drug depot carrying bone-targeted drugs is another strategy. In this review, we summarize the bone-targeted hydrogel through application environment, construction strategies and disease applications. We hope this article will provide a reference for the development of bone-targeted hydrogels. We also hope this article could increase awareness of bone-targeted materials.

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Introducing the microenvironment and target molecules in different parts of long bones.

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Summarizing the construction strategy of micro/nanoparticle hydrogel with bone targeting properties.

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Summarizing the construction strategy of hydrogel based depot carrying bone-targeted drugs.

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Reporting the application and effect of bone targeting hydrogel in common bone diseases.

99mTc-NTP 15-5 is a companion radiotracer for assessing joint functional response to sprifermin (rhFGF-18) in a murine osteoarthritis model

With the emergence of disease modifying osteoarthritis drugs (DMOAD), imaging methods to quantitatively demonstrate their efficacy and to monitor osteoarthritis progression at the functional level are urgently needed. Our group showed that articular cartilage can be quantitatively assessed in nuclear medicine imaging by our radiotracer ^99mTc-NTP 15-5 targeting cartilage proteoglycans. In this work, surgically induced DMM mice were treated with sprifermin or saline. We investigated cartilage remodelling in the mice knees by ^99mTc-NTP 15-5 SPECT-CT imaging over 24 weeks after surgery, as wells as proteoglycan biochemical assays. OA alterations were scored by histology according to OARSI guidelines. A specific accumulation of ^99mTc-NTP 15-5 in cartilage joints was evidenced in vivo by SPECT-CT imaging as early as 30 min post-iv injection. In DMM, ^99mTc-NTP 15-5 accumulation in cartilage within the operated joints, relative to contralateral ones, was observed to initially increase then decrease as pathology progressed. Under sprifermin, ^99mTc-NTP 15-5 uptake in pathological knees was significantly increased compared to controls, at 7-, 12- and 24-weeks, and consistent with proteoglycan increase measured 5 weeks post-surgery, as a sign of cartilage matrix remodelling. Our work highlights the potential of ^99mTc-NTP 15-5 as an imaging-based companion to monitor cartilage remodelling in OA and DMOAD response.

Moving Beyond the Limits of Detection: The Past, the Present, and the Future of Diagnostic Imaging in Canine Osteoarthritis

Osteoarthritis (OA) is the most common orthopedic condition in dogs, characterized as the chronic, painful end-point of a synovial joint with limited therapeutic options other than palliative pain control or surgical salvage. Since the 1970s, radiography has been the standard-of-care for the imaging diagnosis of OA, despite its known limitations. As newer technologies have been developed, the limits of detection have lowered, allowing for the identification of earlier stages of OA. Identification of OA at a stage where it is potentially reversible still remains elusive, however, yet there is hope that newer technologies may be able to close this gap. In this article, we review the changes in the imaging of canine OA over the past 50 years and give a speculative view on future innovations which may provide for earlier identification, with the ultimate goal of repositioning the limit of detection to cross the threshold of this potentially reversible disease.

Chondroitin sulfate-functionalized lipid nanoreservoirs: a novel cartilage-targeting approach for intra-articular delivery of cassic acid for osteoarthritis treatment

Novel intra-articular nanoreservoirs were implemented employing different cartilage targeting approaches to improve cartilage bioavailability of a chondroprotective drug, cassic acid (CA), for effective amelioration of cartilage deterioration off-targeting CA gastrointestinal disorders. Herein, we compared active cartilage-targeting approach via chondroitin sulfate (CHS) functionalization versus passive targeting using positively charged nanoparticles to target negatively charged cartilage matrix. Firstly, CA integrated nanoreservoirs (CA-NRs) were fabricated based on ionic conjugation between CA and cationic hydrophobic surface modifier octadecylamine (ODA) and were further functionalized with CHS to develop CHS-CA-NRs. Confocal laser microscope was used to visualize the accumulation of nanoparticles into the cartilage tissue. Both targeting approaches promoted CA local cartilage availability and prolonged its residence time. Compared to passive targeted CA-NRs, active targeted CHS-CA-NRs showed higher fluorescence signals in proximity to and inside chondrocytes which lasted for up to 21 days. In MIA-osteoarthritic rats, CHS-CA-NRs showed superior antiosteoarthritic activity, exhibiting highest cartilage repair compared to CA-NRs. Additionally, CHS-CA-NRs significantly inhibited OA inflammatory cytokine, degradation enzyme and oxidative stress and improved cartilage matrix biosynthesis. Conclusively, CHS-CA-NRs improved OA repair showing a superior efficacy for articular cartilage targeting with CHS which could be a potential advance for OA therapy.

Dual-radiolabelling of an injectable hyaluronan-tyramine-bisphosphonate hybrid gel for in vitro and in vivo tracking

Hyaluronan (HA) have been widely used as the ideal biomaterials. It is important to understand their degradation and distribution for better optimization. From a new aspect of using radiotracers, we designed the HA-tyramine-bisphosphonate derivative for dual-labelling with two radionuclides (^99mTc and ¹³¹I) simultaneously for in vitro and in vivo tracking. This dual-radiolabelled HA derivative can still be non-covalently crosslinked by hydroxyapatites to form injectable gel. The excellent properties of the gel, such as robust, biodegradable, and self-healing capacity were maintained. We firstly proved the possibility to distinguish different radionuclides in the degraded gel using the high-resolution gamma-ray spectrometry. The radiolabelled gel showed lower toxicity than pure hydroxyapatites against various cell lines, while the in vivo results proved that the ^99mTc/¹³¹I-labelling of the gel was safe and stable enough for imaging and quantitatively tracking. The present method can also be applied for the development of dual-radiolabelled gels from other polysaccharides.