Amplifying endogenous stem cell migration for in situ bone tissue formation: Substance P analog and BMP mimetic peptide-loaded click-crosslinked hyaluronic acid hydrogel.

Endogenous stem cell-driven in situ bone tissue formation has recently garnered increasing attention. Therefore, our study sought to refine methods to enhance the migration and subsequent osteogenic differentiation of these cells. Our innovative approach involves using an injectable hydrogel that combines click cross-linking sites and a BMP-2 mimetic peptide (BP) with hyaluronic acid (HA). This injectable formulation, hereinafter referred to as SPa + Cx-HA-BP, incorporates a substance P analog peptide (SPa) with Cx-HA-BP, proving versatile for in vitro and in vivo applications without cytotoxicity. The controlled release of SPa creates a gradient that guides endogenous stem cells towards the Cx-HA scaffold from specific tissue niches. Both Cx-HA and SPa+Cx-HA induced minimal changes in the expression of genes associated with osteogenic differentiation. In contrast, these genes were robustly induced by both SPa + Cx-HA+BP and SPa + Cx-HA-BP, in which BP was respectively integrated via physical and chemical methods. Remarkably, chemically incorporating BP (Cx-HA-BP) resulted in 4-9 times higher osteogenic gene expression than physically mixed BP in Cx-HA+BP. This study validates the role of SPa role in guiding endogenous stem cells toward the hydrogel and underscores the substantial impact of sustained BP presence within the hydrogel. Collectively, our findings offer valuable insights for the development of innovative strategies to promote endogenous stem cell-based tissue regeneration. The developed hydrogel effectively guides stem cells from their natural locations and facilitates sustained osteogenic differentiation, thus holding great promise for applications in regenerative medicine.

ATN Classification and Clinical Progression of the Amyloid-Negative Group in Alzheimer's Disease Neuroimaging Initiative Participants.

Alzheimer's disease has recently been classified using three biological markers (amyloid [A], tau [T], and neurodegeneration [N]) to help elucidate its progression. We aimed to investigate whether there were differences between cognitive function and the clinical dementia symptoms over time relative to the ATN classification in the amyloid-negative group. In the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort, 310 participants who underwent all the tests required for ATN classification were enrolled. The cognitive function score differences (Alzheimer's Disease Assessment Scale-Cognitive Subscale 13 [ADAS-Cog 13], Clinical Dementia Rating Sum of Boxes [CDR-SOB], and Mini-Mental State Examination [MMSE]) between the groups were analyzed using the analysis of covariance and score changes over time with a linear mixed-effects model. In the cross-sectional analysis, ADAS-Cog 13 scores were higher for A-T-N+ and A-T+N+ than for A-T-N- (p<0.001) and A-T+N- (p<0.001). In the longitudinal analysis, CDR-SOB scores for A-T+N+ deteriorated faster than A-T-N- (p<0.001), A-T+N- (p<0.001) and A-T-N+ (p<0.001). Hippocampal atrophy progressed faster in A-T-N+ (p<0.001) and A-T+N+ (p=0.02) than in A-T-N-. Through this study, we discovered that even in individuals classified as amyloid negative, neurodegeneration with tau deposition exacerbates cognitive decline and worsens clinical symptoms, underscoring the need for continuous monitoring and observation.

In-situ wound healing by SDF-1-mimic peptide-loaded click crosslinked hyaluronic acid scaffold.

Endogenous stem cell-based in-situ tissue regeneration has recently gained considerable attention. In this study, we investigated the potential of a chemokine, SDF-1-mimic peptide (SMP), to promote endogenous stem cell-based in-situ wound healing. Our approach involved the development of a click crosslinked hyaluronic acid scaffold loaded with SMP (Cx-HA + SMP) to release SMP in a wound site. The Cx-HA scaffold maintained its structural integrity throughout the wound healing process and also captured endogenous stem cells. Gradual SMP release from the Cx-HA + SMP scaffold established a concentration gradient at the wound site. In animal wound experiments, Cx-HA + SMP exhibited faster wound contraction compared to Cx-HA + SDF-1. Additionally, Cx-HA + SMP resulted in approximately 1.2-1.6 times higher collagen formation compared to Cx-HA + SDF-1. SMP released from the Cx-HA + SMP scaffold promoted endogenous stem cell migration to the wound site 1.5 times more effectively than Cx-HA + SDF-1. Moreover, compared to Cx-HA + SDF-1, Cx-HA + SMP exhibited higher expression of CXCR4 and CD31, as well as the positive markers CD29 and CD44 for endogenous stem cells. The endogenous stem cells that migrated through Cx-HA + SMP regenerated into wound skin with minimal scar granule formation, similar to the normal tissue. In conclusion, SMP peptide offers greater convenience, while efficiently attracting migrating endogenous stem cells compared to the SDF protein. Our findings suggest that Cx-HA + SMP scaffolds hold promise as a strategy to enhance endogenous stem cell-based in-situ wound healing.

Enhanced intra-articular therapy for rheumatoid arthritis using click-crosslinked hyaluronic acid hydrogels loaded with toll-like receptor antagonizing peptides.

Rheumatoid arthritis (RA) is a chronic inflammatory disorder that results in the deterioration of joint cartilage and bone. Toll-like receptor 4 (TLR4) has been pinpointed as a key factor in RA-related inflammation. While Toll-like receptor antagonizing peptide 2 (TAP2) holds potential as an anti-inflammatory agent, its in vivo degradation rate hinders its efficacy. We engineered depots of TAP2 encapsulated in click-crosslinked hyaluronic acid (TAP2+Cx-HA) for intra-articular administration, aiming to enhance the effectiveness of TAP2 as an anti-inflammatory agent within the joint cavity. Our data demonstrated that FI-TAP2+Cx-HA achieves a longer retention time in the joint cavity compared to FI-TAP2 alone. Mechanistically, we found that TAP2 interacts with TLR4 on the cell membranes of inflammatory cells, thereby inhibiting the nuclear translocation of NF-κB and maintaining it in an inactive cytoplasmic state. In a rat model of RA, the TAP2+Cx-HA formulation effectively downregulated the inflammatory cytokines TNF-α and IL-6, while upregulating the anti-inflammatory cytokine IL-10 and the therapeutic protein 14-3-3ζ. This led to a more rapid restoration of cartilage thickness, increased deposition of glycosaminoglycans, and new bone tissue formation in the regenerated cartilage, in comparison to a single TAP2 treatment after a six-week period. Our results suggest that TAP2+Cx-HA could serve as a potent intra-articular treatment for RA, offering both symptomatic relief and promoting cartilage regeneration. This innovative delivery system holds significant promise for improving the management of RA and other inflammatory joint conditions. STATEMENT OF SIGNIFICANCE: In this study, we developed a therapy by creating toll-like receptor 4 (TLR4)-antagonizing peptide (TAP2)-loaded click-crosslinked hyaluronic acid (TAP2+Cx-HA) depots for direct intra-articular injection. Our study demonstrates that FI-TAP2+Cx-HA exhibits a more than threefold longer lifetime in the joint cavity compared to FI-TAP2 alone. Furthermore, we found that TAP2 binds to TLR4 and masks the nuclear localization signals of NF-κB, leading to its sequestration in an inactive state in the cytoplasm. In a rat model of RA, TAP2+Cx-HA effectively suppresses inflammatory molecules, specifically TNF-α and IL-6, while upregulating the anti-inflammatory cytokine IL-10 and the therapeutic protein 14-3-3ζ. This resulted in faster regeneration of cartilage thickness, increased glycosaminoglycan deposits in the regenerated cartilage, and a twofold increase in new bone tissue formation compared to a single TAP2 treatment.

Development and In Vivo Assessment of an Injectable Cross-Linked Cartilage Acellular Matrix-PEG Hydrogel Scaffold Derived from Porcine Cartilage for Tissue Engineering.

The cartilage acellular matrix (CAM) derived from porcine cartilage, which does not induce significant inflammation and provides an environment conducive for cell growth and differentiation, is a promising biomaterial candidate for scaffold fabrication. However, the CAM has a short period in vivo, and the in vivo maintenance is not controlled. Therefore, this study is aimed at developing an injectable hydrogel scaffold using a CAM. The CAM is cross-linked with a biocompatible polyethylene glycol (PEG) cross-linker to replace typically used glutaraldehyde (GA) cross-linker. The cross-linking degree of cross-linked CAM by PEG cross-linker (Cx-CAM-PEG) according to the ratios of the CAM and PEG cross-linker is confirmed by contact angle and heat capacities measured by differential scanning calorimetry. The injectable Cx-CAM-PEG suspension exhibits controllable rheological properties and injectability. Additionally, injectable Cx-CAM-PEG suspensions with no free aldehyde group are formed in the in vivo hydrogel scaffold almost simultaneously with injection. In vivo maintenance of Cx-CAM-PEG is realized by the cross-linking ratio. The in vivo formed Cx-CAM-PEG hydrogel scaffold exhibits certain host-cell infiltration and negligible inflammation within and near the transplanted Cx-CAM-PEG hydrogel scaffold. These results suggest that injectable Cx-CAM-PEG suspensions, which are safe and biocompatible in vivo, represent potential candidates for (pre-)clinical scaffolds.

Comparative effectiveness of combined antiplatelet treatments in acute minor ischaemic stroke.

BACKGROUND: No study has thoroughly compared the effectiveness of combined antiplatelet treatments (other than clopidogrel-aspirin) versus clopidogrel-aspirin or aspirin alone for early secondary prevention in acute ischaemic stroke. METHODS: We identified patients with acute, minor, non-cardiogenic ischaemic stroke treated with aspirin alone, clopidogrel-aspirin or other combination treatment. Propensity scores considering the inverse probability of treatment weighting were used to adjust for baseline imbalances. The primary outcome was the composite of all strokes (ischaemic or haemorrhagic), myocardial infarction and all-cause mortality at 3 months. RESULTS: Among 12 234 patients (male: 61.9%; age: 65.5±13 years) who met the eligibility criteria, aspirin, clopidogrel-aspirin and other combination treatments were administered in 52.2%, 42.9% and 4.9% of patients, respectively. In the crude analysis, the primary outcome event at 3 months occurred in 14.5% of the other combination group, 14.4% of the aspirin group and 13.0% of the clopidogrel-aspirin group. In the weighted Cox proportional hazards analysis, the 3-month primary outcome event occurred less frequently in the clopidogrel-aspirin group than in the other combination group (weighted HR: 0.82 (0.59-1.13)), while no association was found between the aspirin group (weighted HR: 1.04 (0.76-1.44)) or other combination group and the 3-month primary outcome. CONCLUSION: Other combined antiplatelet treatment, compared with aspirin alone or clopidogrel-aspirin, was not associated with reduced risks of primary composite vascular events or recurrent stroke during the first 3 months after stroke. Therefore, the results suggest that other combination treatments, particularly the cilostazol-based combination, may not be effective alternatives for clopidogrel-aspirin to prevent early vascular events in patients with acute minor stroke. Further exploration in clinical trials will be needed.

Crystallization Behavior of Amorphous Si3N4 and Particle Size Control of the Crystallized α-Si3N4.

Amorphous silicon nitride powder prepared by low-temperature vapor-phase reaction was heat treated at various temperatures for different periods of time to examine the crystallization behavior. The effects of the heat-treatment temperature and duration on the degree of crystallization were investigated along with the effect of the heat-up rate on the particle size, and its distribution, of the crystallized α-phase silicon nitride powder. A phase transition from amorphous to α-phase occurred at a temperature above 1400 degrees C. The crystallization. process was completed after heat treatment at 1500 degrees C for 3 h or at 1550 degrees C for 1 h. The crystallization process starts at the surface of the amorphous particle: while the outer regions of the particle become crystalline, the inner part remains amorphous. The re-arrangement of the Si and N atoms on the surface of the amorphous particle leads to the formation of hexagonal crystals that are separated from the host amorphous particle. The particle size and size distribution can be controlled by varying the heat-treatment profile (namely, the heat-treatment temperature, heating rate, and heating duration at the specified temperature), which can be used to control the relative extent of the nucleation and growth. The completion of most of the nucleation process by lowering the heat-up rate can be used to achieve a singlet particle size distribution. Bimodal particle size distribution can be achieved by fast heat-up during the crystallization process.