Engineering approaches for RNA-based and cell-based osteoarthritis therapies

Shear-thinning hydrogel for allograft cell transplantation and externally controlled transgene expression

This work establishes the design of a fully synthetic, shear-thinning hydrogel platform that is injectable and can isolate engineered, allogeneic cell therapies from the host. We utilized RAFT to generate a library of linear random copolymers of N,N-dimethylacrylamide (DMA) and 2-vinyl-4,4-dimethyl azlactone (VDMA) with variable mol% VDMA and degree of polymerization. Poly(DMA-co-VDMA) copolymers were subsequently modified with either adamantane (Ad) or β-cyclodextrin (Cd) through amine-reactive VDMA to prepare hydrogel precursor macromers containing complementary guest-host pairing pendant groups that, when mixed, form shear-thinning hydrogels. Rheometric evaluation of the hydrogel library enabled identification of lead macromer structures comprising 15 mol% pendants (Ad or Cd) and a degree of polymerization of 1000; mixing of these Ad and Cd functionalized precursors yielded hydrogels possessing storage modulus above 1000 Pa, tan(δ) values below 1 and high yield strain, which are target characteristics of robust but injectable shear-thinning gels. This modular system proved amenable to nanoparticle integration with surface-modified nanoparticles displaying Ad. The addition of the Ad-functionalized nanoparticles simultaneously improved mechanical properties of the hydrogels and enabled extended hydrogel retention of a model small molecule in vivo. In studies benchmarking against alginate, a material traditionally used for cell encapsulation, the lead hydrogel showed significantly less fibrous encapsulation in a subcutaneous implant site. Finally, this platform was utilized to encapsulate and extend in vivo longevity of inducible transgene-engineered mesenchymal stem cells in an allogeneic transplant model. The hydrogels remained intact and blocked infiltration by host cells, consequently extending the longevity of grafted cell function relative to a benchmark, shear-thinning hyaluronic acid-based gel. In sum, the new synthetic, shear-thinning hydrogel system presented here shows potential for further development as an injectable platform for delivery and in situ drug modulation of allograft and engineered cell therapies.

Ion channels in osteoarthritis: emerging roles and potential targets

Osteoarthritis (OA) is a highly prevalent joint disease that causes substantial disability, yet effective approaches to disease prevention or to the delay of OA progression are lacking. Emerging evidence has pinpointed ion channels as pivotal mediators in OA pathogenesis and as promising targets for disease-modifying treatments. Preclinical studies have assessed the potential of a variety of ion channel modulators to modify disease pathways involved in cartilage degeneration, synovial inflammation, bone hyperplasia and pain, and to provide symptomatic relief in models of OA. Some of these modulators are currently being evaluated in clinical trials. This review explores the structures and functions of ion channels, including transient receptor potential channels, Piezo channels, voltage-gated sodium channels, voltage-dependent calcium channels, potassium channels, acid-sensing ion channels, chloride channels and the ATP-dependent P2XR channels in the osteoarthritic joint. The discussion spans channel-targeting drug discovery and potential clinical applications, emphasizing opportunities for further research, and underscoring the growing clinical impact of ion channel biology in OA.

Identification of biomarkers and potential drug targets in osteoarthritis based on bioinformatics analysis and mendelian randomization

Background

Osteoarthritis (OA) can lead to chronic joint pain, and currently there are no methods available for complete cure. Utilizing the Gene Expression Omnibus (GEO) database for bioinformatics analysis combined with Mendelian randomization (MR) has been widely employed for drug repurposing and discovery of novel therapeutic targets. Therefore, our research focus is to identify new diagnostic markers and improved drug target sites.

Methods

Gene expression data from different tissues of synovial membrane, cartilage and subchondral bone were collected through GEO data to screen out differential genes. Two-sample MR Analysis was used to estimate the causal effect of expression quantitative trait loci (eQTL) on OA. Through the intersection of the two, core genes were obtained, which were further screened by bioinformatics analysis for in vitro and in vivo molecular experimental verification. Finally, drug prediction and molecular docking further verified the medicinal value of drug targets.

Results

In the joint analysis utilizing the GEO database and MR approach, five genes exhibited significance across both analytical methods. These genes were subjected to bioinformatics analysis, revealing their close association with immunological functions. Further refinement identified two core genes (ARL4C and GAPDH), whose expression levels were found to decrease in OA pathology and exhibited a protective effect in the MR analysis, thus demonstrating consistent trends. Support from in vitro and in vivo molecular experiments was also obtained, while molecular docking revealed favorable interactions between the drugs and proteins, in line with existing structural data.

Conclusion

This study identified potential diagnostic biomarkers and drug targets for OA through the utilization of the GEO database and MR analysis. The findings suggest that the ARL4C and GAPDH genes may serve as therapeutic targets, offering promise for personalized treatment of OA.

METTL3 regulates cartilage development and homeostasis by affecting Lats1 mRNA stability in an m6A-YTHDF2-dependent manner

Cartilage maintains the structure and function of joints, with disturbances leading to potential osteoarthritis. N6-methyladenosine (m6A), the most widespread post-transcriptional modification in eukaryotes, plays a crucial role in regulating biological processes. While current research has indicated that m6A affects the progression of osteoarthritis, its function in the development and homeostasis of articular cartilage remains unclear. Here we report that Mettl3 deficiency in chondrocytes leads to mandibular condylar cartilage morphological alterations, early temporomandibular joint osteoarthritis, and diminished adaptive response to abnormal mechanical stimuli. Mechanistically, METTL3 modulates Lats1 mRNA methylation and facilitates its degradation in an m6A-YTHDF2-dependent manner, which subsequently influences the degradation and nuclear translocation of YAP1. Intervention with the Hippo pathway inhibitor XMU-MP-1 alleviates condylar abnormality caused by Mettl3 knockout. Our findings demonstrate the role of METTL3 in cartilage development and homeostasis, offering insights into potential treatment strategies for osteoarthritis.

Pharmacotherapy for osteoarthritis-related pain: current and emerging therapies

INTRODUCTION

Osteoarthritis (OA) related pain has affected millions of people worldwide. However, the current pharmacological options for managing OA-related pain have not achieved a satisfactory effect.

AREAS COVERED

This narrative review provides an overview of the current and emerging drugs for OA-related pain. It covers the drugs' mechanism of action, safety, efficacy, and limitations. The National Library of Medicine (PubMed) database was primarily searched from 2000 to 2024.

EXPERT OPINION

Current treatment options are limited and suboptimal for OA pain management. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are the recognized and first-line treatment in the management of OA-related pain, and other drugs are inconsistent recommendations by guidelines. Emerging treatment options are promising for OA-related pain, including nerve growth factor (NGF) inhibitors, ion channel inhibitors, and calcitonin gene-related peptide (CGRP) antagonists. Besides, drugs repurposing from antidepressants and antiepileptic analgesics are shedding light on the management of OA-related pain. The management of OA-related pain is challenging as pain is heterogeneous and subjective. A more comprehensive strategy combined with non-pharmacological therapy needs to be considered, and tailored management options to individualized patients.

Effective delivery of miR-150-5p with nucleus pulposus cell-specific nanoparticles attenuates intervertebral disc degeneration

BACKGROUND

The use of gene therapy to deliver microRNAs (miRNAs) has gradually translated to preclinical application for the treatment of intervertebral disc degeneration (IDD). However, the effects of miRNAs are hindered by the short half-life time and the poor cellular uptake, owing to the lack of efficient delivery systems. Here, we investigated nucleus pulposus cell (NPC) specific aptamer-decorated polymeric nanoparticles that can load miR-150-5p for IDD treatment.

METHODS

The role of miR-150-5p during disc development and degeneration was examined by miR-150-5p knockout (KO) mice. Histological analysis was undertaken in disc specimens. The functional mechanism of miR-150-5p in IDD development was investigated by qRT-PCR assay, Western blot, coimmunoprecipitation and immunofluorescence. NPC specific aptamer-decorated nanoparticles was designed, and its penetration, stability and safety were evaluated. IDD progression was assessed by radiological analysis including X-ray and MRI, after the annulus fibrosus needle puncture surgery with miR-150-5p manipulation by intradiscal injection of nanoparticles. The investigations into the interaction between aptamer and receptor were conducted using mass spectrometry, molecular docking and molecular dynamics simulations.

RESULTS

We investigated NPC-specific aptamer-decorated polymeric nanoparticles that can bind to miR-150-5p for IDD treatment. Furthermore, we detected that nanoparticle-loaded miR-150-5p inhibitors alleviated NPC senescence in vitro, and the effects of the nanoparticles were sustained for more than 3 months in vivo. The microenvironment of NPCs improves the endo/lysosomal escape of miRNAs, greatly inhibiting the secretion of senescence-associated factors and the subsequent degeneration of NPCs. Importantly, nanoparticles delivering miR-150-5p inhibitors attenuated needle puncture-induced IDD in mouse models by targeting FBXW11 and inhibiting TAK1 ubiquitination, resulting in the downregulation of NF-kB signaling pathway activity.

CONCLUSIONS

NPC-targeting nanoparticles delivering miR-150-5p show favorable therapeutic efficacy and safety and may constitute a promising treatment for IDD.

Platelet-Rich Plasma in the Management of Temporomandibular Joint Pain in Young Adults With Temporomandibular Disorder

BACKGROUND

Temporomandibular disorder (TMD) encompasses a range of conditions affecting the temporomandibular joint (TMJ) and associated structures, with TMJ pain being a prevalent symptom. Conventional management strategies have limitations, which require the exploration of innovative interventions. Platelet-rich plasma (PRP), known for its regenerative properties, presents a potential therapeutic avenue. This study aims to investigate the effectiveness of PRP in reducing the pain associated with mild TMJ in young adults.

METHODOLOGY

Participants (n = 128) aged 18 to 35 years with mild TMD were evenly randomized into PRP treatment and placebo control groups. PRP was prepared using a standardized protocol, and intra-articular injections were administered. Placebo injections mimic PRP. Follow-up evaluations were carried out at four and eight weeks after the intervention.

RESULTS

The study successfully randomized comparable groups, and the PRP treatment group experienced a significant reduction in TMJ pain (visual analog scale [VAS] score: 6.8 ± 1.2 to 2.1 ± 1.0 at eight weeks, P < 0.001). The PRP treatment also increased the largest opening of the mouth (from 38.2 ± 2.5 to 43.5 ± 3.1, P < 0.001) and the number of lateral movements (12.3 ± 1.5 to 14.9 ± 2.0, P < 0.001), while the placebo group had very few changes. Positive patient-reported outcomes on daily activities were observed, with no serious complications reported in either group.

CONCLUSIONS

This study provides evidence supporting the efficacy of PRP in reducing TMJ pain, improving jaw function, and improving quality of life in young adults with mild TMD. The results underscore the potential of PRP as a minimally invasive intervention for TMJ disorders.

A programmable arthritis-specific receptor for guided articular cartilage regenerative medicine

Objective

Investigational cell therapies have been developed as disease-modifying agents for the treatment of osteoarthritis (OA), including those that inducibly respond to inflammatory factors driving OA progression. However, dysregulated inflammatory cascades do not specifically signify the presence of OA. Here, we deploy a synthetic receptor platform that regulates cell behaviors in an arthritis-specific fashion to confine transgene expression to sites characterized by cartilage degeneration.

Methods

An scFv specific for type II collagen (CII) was used to produce a synthetic Notch (synNotch) receptor that enables "CII-synNotch" mesenchymal stromal cells (MSCs) to recognize CII fibers exposed in damaged cartilage. Engineered cell activation by both CII-treated culture surfaces and on primary tissue samples was measured via inducible reporter transgene expression. TGFβ3-expressing cells were assessed for cartilage anabolic gene expression via qRT-PCR. In a co-culture with CII-synNotch MSCs engineered to express IL-1Ra, ATDC5 chondrocytes were stimulated with IL-1α, and inflammatory responses of ATDC5s were profiled via qRT-PCR and an NF-κB reporter assay.

Results

CII-synNotch MSCs are highly responsive to CII, displaying activation ranges over 40-fold in response to physiologic CII inputs. CII-synNotch cells exhibit the capacity to distinguish between healthy and damaged cartilage tissue and constrain transgene expression to regions of exposed CII fibers. Receptor-regulated TGFβ3 expression resulted in upregulation of Acan and Col2a1 in MSCs, and inducible IL-1Ra expression by engineered CII-synNotch MSCs reduced pro-inflammatory gene expression in chondrocytes.

Conclusion

This work demonstrates proof-of-concept that the synNotch platform guides MSCs for spatially regulated, disease-dependent delivery of OA-relevant biologic drugs.