Sustained Local Release of Methylprednisolone From a Thiol-Acrylate Poly(Ethylene Glycol) Hydrogel for Treating Chronic Compressive Radicular Pain

Factors That Influence Base-Catalyzed Thiol-Ene Hydrogel Synthesis

Injectable, localized drug delivery using hydrogels made from ethoxylated trimethylolpropane tri-3-mercaptopropionate (ETTMP) and poly(ethylene glycol) diacrylate (PEGDA) has shown great potential due to these hydrogels' ability to exhibit non-swelling behavior and tunable drug release properties. However, current synthesis methods in the literature suffer from poor ETTMP solubility in water, slow gelation times exceeding 20 min, and a lack of reproducibility. To address these limitations, we have developed a reliable synthesis procedure and conducted a sensitivity analysis of key variables. This has enabled us to synthesize ETTMP-PEGDA hydrogels in a polymer concentration range of 15 to 90 wt% with gelation times of less than 2 min and moduli ranging from 3.5 to 190 kPa. We overcame two synthesis limitations by identifying the impact of residual mercaptopropionic acid and alumina purification column height on gelation time and by premixing ETTMP and PEGDA to overcome low ETTMP solubility in water. Our ETTMP-PEGDA mixture can be stored at -20 °C for up to 2 months without crosslinking, allowing easy storage and shipment. These and previous results demonstrate the potential of ETTMP-PEGDA hydrogels as promising candidates for injectable, localized drug delivery with tunable drug release properties.

Single-Cell Sequencing Reveals the Optimal Time Window for Anti-Inflammatory Treatment in Spinal Cord Injury

Though the occurrence of neuroinflammation after spinal cord injury (SCI) is essential for antigen clearance and tissue repair, excessive inflammation results in cell death and axon dieback. The effect of anti-inflammatory medicine used in clinical treatment remains debatable owing to the inappropriate therapeutic schedule that does not align with the biological process of immune reaction. A better understanding of the immunity process is critical to promote effective anti-inflammatory therapeutics. However, cellular heterogeneity, which results in complex cellular functions, is a major challenge. This study performs single-cell RNA sequencing by profiling the tissue proximity to the injury site at different time points after SCI. Depending on the analysis of single-cell data and histochemistry observation, an appropriate time window for anti-inflammatory medicine treatment is proposed. This work also verifies the mechanism of typical anti-inflammatory medicine methylprednisolone sodium succinate (MPSS), which is found attributable to the activation inhibition of cells with pro-inflammatory phenotype through the downregulation of pathways such as TNF, IL2, and MIF. These pathways can also be provided as targets for anti-inflammatory treatment. Collectively, this work provides a therapeutic schedule of 1-3 dpi (days post injury) to argue against classical early pulse therapy and provides some pathways for target therapy in the future.

Sustain release of loaded insulin within biomimetic hydrogel microsphere for sciatic tissue engineering in vivo

We developed insulin loaded biomimetic microsphere by laccase-mediated crosslinking using a microfluidic device in the water-in-oil emulsion system as an injectable vehicle for the repair of sciatic tissue. Aqueous polymeric solution of phenol-substituted hyaluronic acid (HAPh) and collagen (ColPh) containing insulin and laccase flowed from the inner channel into oil flow within an outer channel which leads formation of hydrogel microsphere. The physical properties of prepared specimens including swelling rate, mechanical resistance and the prolonged release rate of microspheres proved applicability of fabricated vehicles for tissue engineering and drug delivery systems. The growth profile and behavior of cells in microspheres indicated cytocompatibility of the method and prepared vehicles for microtissue development. Histopathological examination revealed a significant increase in axonal regeneration, and remyelination process in injured sciatic nerve following treatment with HAPh/ColPh microspheres containing insulin compared to control groups. Also, the functional characteristic of sciatic tissue showed that the presence of biomimetic microsphere and insulin simultaneously had improved sciatic tissue functions including functional sciatic index (SFI) values, reaction to hot plate and muscle weight of rats. In summary, the results proved that composite biomimetic microspheres containing insulin effectively improved nerve regeneration in the rat model.

Osteoking Decelerates Cartilage Degeneration in DMM-Induced Osteoarthritic Mice Model Through TGF-β/smad-dependent Manner

Osteoarthritis (OA) is a common disease characterized by cartilage degeneration. In recent years much attention has been paid to Traditional Chinese Medicine (TCM) since its treatments have shown efficacy for ameliorating cartilage degradation with mild side effects. Osteoking is a TCM prescription that has long been used in OA treatment. However, the exact mechanism of Osteoking are not fully elucidated. In the current study, destabilization of the medial meniscus (DMM)-induced OA mice was introduced as a wild type animal model. After 8 weeks of administration of Osteoking, histomorphometry, OARSI scoring, gait analysis, micro-CT, and immunohistochemical staining for Col2, MMP-13, TGFβRII and pSmad-2 were conducted to evaluate the chondroprotective effects of Osteoking in vivo. Further in vitro experiments were then performed to detect the effect of Osteoking on chondrocytes. TGFβRII^Col2ER transgenic mice were constructed and introduced in the current study to validate whether Osteoking exerts its anti-OA effects via the TGF-β signaling pathway. Results demonstrated that in wild type DMM mice, Osteoking ameliorated OA-phenotype including cartilage degradation, subchondral bone sclerosis, and gait abnormality. Col2, TGFβRII, and pSmad-2 expressions were also found to be up-regulated after Osteoking treatment, while MMP-13 was down-regulated. In vitro, the mRNA expression of MMP-13 and ADAMTS5 decreased and the mRNA expression of Aggrecan, COL2, and TGFβRII were up-regulated after the treatment of Osteoking in IL-1β treated chondrocytes. The additional treatment of SB505124 counteracted the positive impact of Osteoking on primary chondrocytes. In TGFβRII^Col2ER mice, spontaneous OA-liked phenotype was observed and treatment of Osteoking failed to reverse the OA spontaneous progression. In conclusion, Osteoking ameliorates OA progression by decelerating cartilage degradation and alleviating subchondral bone sclerosis partly via the TGF-β signaling pathway.

Biomaterial Strategies to Bolster Neural Stem Cell-Mediated Repair of the Central Nervous System

Stem cell therapies have the potential to not only repair, but to regenerate tissue of the central nervous system (CNS). Recent studies demonstrate that transplanted stem cells can differentiate into neurons and integrate with the intact circuitry after traumatic injury. Unfortunately, the positive findings described in rodent models have not been replicated in clinical trials, where the burden to maintain the cell viability necessary for tissue repair becomes more challenging. Low transplant survival remains the greatest barrier to stem cell-mediated repair of the CNS, often with fewer than 1-2% of the transplanted cells remaining after 1 week. Strategic transplantation parameters, such as injection location, cell concentration, and transplant timing achieve only modest improvements in stem cell transplant survival and appear inconsistent across studies. Biomaterials provide researchers with a means to significantly improve stem cell transplant survival through two mechanisms: (1) a vehicle to deliver and protect the stem cells and (2) a substrate to control the cytotoxic injury environment. These biomaterial strategies can alleviate cell death associated with delivery to the injury and can be used to limit cell death after transplantation by limiting cell exposure to cytotoxic signals. Moreover, it is likely that control of the injury environment with biomaterials will lead to a more reliable support for transplanted cell populations. This review will highlight the challenges associated with cell delivery in the CNS and the advances in biomaterial development and deployment for stem cell therapies necessary to bolster stem cell-mediated repair.

Gait Assessment of Pain and Analgesics: Comparison of the DigiGait™ and CatWalk™ Gait Imaging Systems

Investigation of pain requires measurements of nociceptive sensitivity and other pain-related behaviors. Recent studies have indicated the superiority of gait analysis over traditional evaluations (e.g., skin sensitivity and sciatic function index [SFI]) in detecting subtle improvements and deteriorations in animal models. Here, pain-related gait parameters, whose criteria include (1) alteration in pain models, (2) correlation with nociceptive threshold, and (3) normalization by analgesics, were identified in representative models of neuropathic pain (spared nerve injury: coordination data) and inflammatory pain (intraplantar complete Freund’s adjuvant: both coordination and intensity data) in the DigiGait™ and CatWalk™ systems. DigiGait™ had advantages in fixed speed (controlled by treadmill) and dynamic SFI, while CatWalk™ excelled in intrinsic velocity, intensity data, and high-quality 3D images. Insights into the applicability of each system may provide guidance for selecting the appropriate gait imaging system for different animal models and optimization for future pain research.

Jingshu Keli attenuates cervical spinal nerve ligation-induced allodynia in rats through inhibition of spinal microglia and Stat3 activation

BACKGROUND CONTEXT

Cervical radicular pain resulting from mechanical compression of a spinal nerve secondary to spinal degenerative alternations negatively impacts patients' quality of life. Jingshu Keli (JSKL), a traditional Chinese medicine formula with multiple active compounds, has been prescribed for pain management in patients with cervical radiculopathy for decades. Two major components of JSKL, ferulic acid and cinnamaldehyde, were identified to have anti-inflammation effect via inhibiting activation of Stat3.

PURPOSE

To investigate the efficacy of JSKL by investigating its mechanism in attenuating cervical radiculopathy-induced mechanical allodynia via modulation activation of spinal microglia and phosphorylation of signal transducer and activator of transcription 3 (Stat3).

STUDY DESIGN

An in vivo animal experiment.

METHODS

Cervical radiculopathy of rats was established by C7 spinal nerve ligation (SNL) with 6-0 silk suture. The effect of postoperational daily gavage of JSKL on mechanical allodynia of rats was tested on day 3, 7, and 14 after surgery. Furthermore, spinal glial cells activation and phosphorylation of Stat3 (p-Stat3) were tested with immunofluorescence imaging and Western blot.

RESULT

The JSKL significantly inhibited SNL-induced allodynia as well as microglia activation in the spinal cord on day 7 and 14 after surgery. Moreover, expression of p-Stat3 was decreased in rats with SNL and JSKL treatment in comparison with rats with SNL and vehicle treatment.

CONCLUSIONS

The JSKL attenuated SNL-induced mechanical allodynia in rats. This analgesic effect might be explained by the suppression of activations of spinal microglia as well as p-Stat3. Our study provides experimental evidence for JSKL as an alternative approach to manage refractory pain in patients with cervical radiculopathy.

The relationship between pro-inflammatory cytokines and pain, appetite and fatigue in patients with advanced cancer

Background

Systemic inflammation is associated with reduced quality of life and increased symptoms in patients with advanced cancer. The aims of this study were to examine the relationships between inflammatory biomarkers and the Patient Reported Outcome Measures (PROMs) of pain, appetite and fatigue; and to explore whether levels of baseline biomarkers were associated with changes in these PROMs following treatment with corticosteroids.

Material and methods

An exploratory analysis was done on a trial examining the analgesic properties of corticosteroids in patients with advanced cancer. Inclusion criteria were: >18 years, taking opioids for moderate or severe cancer pain; pain ≥4 (numerical rating scale 0–10). Serum was extracted and levels of inflammatory biomarkers were assessed. PROMs of pain, appetite and fatigue were assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30 (EORTC QLQ-C30). The relationships between PROMs and inflammatory biomarkers were examined using Spearman Rho-Rank and multiple regression analysis.

Results

Data were available on 49 patients. Levels of sTNF-r1, IL-6, IL-18, MIF, MCP-1, TGF-β1, IL-1ra, and C-reactive protein (CRP) and Erythrocyte sedimentation rate (ESR) were elevated; IL-1β, IL-2, IL-4, IL-8, IL-10, IL-12(p70), interferon-γ, MIP-1α, and TNF-α were below the level of detection. The following correlations were observed: appetite and IL-6 and CRP; fatigue and IL-1ra (r_s: 0.38–0.41, p< .01). There was no association between pretreatment biomarkers and effect from corticosteroid treatment.

Conclusion

In patients with advanced cancer and pain, some pro-inflammatory cytokines were related to appetite and fatigue. Inflammatory biomarkers were not associated with pain or with the efficacy of corticosteroid therapy. Further research examining the attenuation of the systemic inflammatory response and possible effects on symptoms would be of interest.