Collagen Cross-linking Research Articles

Promising LOX proteins for cartilage-targeting osteoarthritis therapy.

Osteoarthritis (OA) is the most affected joint disease worldwide, touching millions of people every year. It is caused by a progressive degeneration of articular cartilage, causing pain and limited mobility. Among the pathways involved in cartilage homeostasis, "LOX" proteins (referring to three distinct protein families, very often confused in the literature) play a prominent role. The lipoxygenase enzyme family is involved in the inflammatory process of OA by inducing the production of several pro-inflammatory leukotrienes. Lectin-like oxidized low-density lipoprotein family are receptors located at the surface of chondrocytes, which interact with their ligand, ox-LDL, activating several catabolic pathways involved in OA pathophysiology. Finally, lysyl oxidase and lysyl oxidase-like are enzymes expressed intracellularly (in chondrocytes' cytoplasm) involved in elastin biosynthesis and collagen cross-linking in cartilage extracellular matrix. EMA and FDA have not yet approved any drug targeting the LOX proteins. In particular, today lysyl oxidase-like 2 is considered as a new promising target for OA modifying therapy. This review clarifies the main roles of different LOX proteins involved in the progression of OA. Potential LOX inhibitoion strategies for drug development in advanced OA therapy, particularly for local intraarticular delivery, were listed and discussed for each target type. This review, therefore, proposes promising strategies for future drug development in OA treatment.

Hyperglycemia inhibits AAA expansion: examining the role of lysyl oxidase.

Abdominal aortic aneurysm (AAA) is a common, progressive, and potentially fatal dilation of the most distal aortic segment. Multiple studies with longitudinal follow-up of AAA have identified markedly slower progression among patients affected with diabetes. Understanding the molecular pathway responsible for the growth inhibition could have implications for therapy in nondiabetic patients with AAA. Toward this end, we investigated the effects of hyperglycemia in a murine model of AAA and a carefully monitored cohort of patients with AAA from the Noninvasive Treatment of AAA-Clinical Trial (NTA3CT). In mice with hyperglycemia, AAA growth was inhibited to a similar degree (∼30%) as seen in patients with diabetes. AAA growth correlated inversely to levels of hyperglycemia in mice and patients with AAA. Inhibiting lysyl oxidase (LOX) activity increases aneurysm growth and matrix degradation in this model. Hyperglycemia increased LOX concentration in aortic smooth muscle cells (SMCs) but not in murine AAA tissue. Inhibiting LOX activity completely blocked the growth-inhibitory effect of hyperglycemia. Lysyl oxidase-like 2 (LOXL2), the primary arterial isoform of LOX, is expressed in the same area as type IV collagen along the outer media in murine AAA tissue. There is a significant inverse correlation between LOXL2 and AAA growth rates in patients. Taken together, these studies suggest a role for LOXL2-mediated type IV collagen crosslinking in slowing AAA growth in the setting of hyperglycemia.NEW & NOTEWORTHY AAA grows slower in patients affected by diabetes. This growth inhibition is lost when the enzyme lysyl oxidase (LOX) is blocked in diabetic mice. The predominant arterial isoform of LOX, LOX-like 2 (LOXL2), overlaps with type IV collagen in the outer media of murine aneurysm tissue. Circulating LOXL2 correlates inversely with AAA growth in patients. Type IV collagen cross-linking by LOXL2 may play a role in the AAA growth inhibition associated with diabetes.

Fibrillin-1 G234D mutation in the hybrid1 domain causes tight skin associated with dysregulated elastogenesis and increased collagen cross-linking in mice

Fibrillin-1, an extracellular matrix (ECM) protein encoded by the FBN1 gene, serves as a microfibril scaffold crucial for elastic fiber formation and homeostasis in pliable tissue such as the skin. Aside from causing Marfan syndrome, some mutations in FBN1 result in scleroderma, marked by hardened and thicker skin which limits joint mobility. Here, we describe a tight skin phenotype in the Fbn1G234D/G234D mice carrying a corresponding variant of FBN1 in the hybrid1 domain that was identified in a patient with familial aortic dissection. Unlike scleroderma, skin thickness and collagen fiber abundance do not change in the Fbn1G234D/G234D mutant skin. Instead, increased collagen cross-links were observed. In addition, short elastic fibers were sparsely located underneath the panniculus muscle layer, and an abundance of thin, aberrant elastic fibers was increased within the subcutaneous fascia, which may have tightened skin attachment to the underlying skeletal muscle. Structurally, Fbn1G234D/G234D microfibrils have a disrupted shoulder region that shares similarities with hybrid1 deletion mutant microfibrils. We then demonstrate the consequence of fibrillin-1 G234D mutation on dermal fibroblast functions. Mutant primary fibroblasts produce fewer elastic fibers, exhibit slower migration and increased cell stiffness. Moreover, secretome from mutant fibroblasts are marked by enhanced secretion of ECM, ECM-modifying enzymes, proteoglycans and cytokines, which are pro-tissue repair/fibrogenic. The transcriptome of mutant fibroblasts displays an increased expression of myogenic developmental and immune-related genes. Our study proposes that imbalanced ECM homeostasis due to a fibrillin-1 G234Dmutation impacts fibroblast properties with potential ramifications on skin function.

Prolonged Impact of Bisphosphonates and Glucocorticoids on Bone Mechanical Properties

Background: This study aimed at investigating the prolonged effects of glucocorticoids and bisphosphonates on bone. Methods: Six-to-eight-month-old skeletally mature male Sprague Dawley rats were randomized to receive a cancer therapy combination of zoledronic acid (ZA = 0.13 mg/kg) and dexamethasone (DX = 3.8 mg/kg) (treatment group, n = 10) or sterile phosphate buffer saline solution (control group, n = 10). The rats received weekly intraperitoneal injections for 8 weeks, which were stopped 6 weeks before euthanasia. Mineralized bone samples were characterized by three-point bending tests, micro-CT imaging, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Bone collagen was assessed using tensile tests on the demineralized bones and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy on mineralized and demineralized bones. Results: The samples in the treatment group showed increased tibial cortical thickness, mineral crystal size, and toughness. Analyses of demineralized tibiae revealed decreased collagen tensile strength in the experimental group. The spectroscopic and TGA/DSC analyses showed that the ZA + DX treatment increased the collagen amide I 1660/1690 cm−1 area ratio and collagen denaturalization temperature, indicating a higher level of collagen cross-linking. Conclusions: Bisphosphonates and glucocorticoids led to prolonged changes in the mechanical properties of bone as a result of increased cortical thickness, increased crystal size, and the deterioration of collagen quality.

Lysyl oxidase nanozyme-loaded hydrogel for sustained release and promotion of diabetic bone defect regeneration.

The process of regenerating bone injuries in diabetic presents significant challenges because lysine oxidase (LOX), a key catalytic enzyme for collagen cross-linking, is inhibited in hyperglycemia. The supplementation of LOX is constrained by inadequate sources and diminished enzymatic activity, necessitating the development of effective alternatives for enhancing bone regeneration in diabetes. Herein, we reported a lysyl oxidase nanozyme (LON), derived from the catalytic domain of LOX. LON formed a stable coordination structure with the active center Cu2+ through histidine imidazolyl nitrogen and quinone oxygen, which is consistent with the conformation of the LOX. Our findings suggested that LON demonstrated the capacity to substitute LOX in promoting collagen synthesis and biomineralization. To enable sustained LON delivery, it was incorporated into a GelMA hydrogel (GH), forming a sustained-release reservoir known as LON-GelMA hydrogel (LONGH). Mechanism of LONGH promoting bone healing to accelerate the crosslinking and maturation stage of collagen were also explored, and the 23 genes closely associated with collagen regeneration and osteogenesis were found to be upregulated. The present investigation outcomes reveal that the engineered LONGH hydrogel presents a novel, simple, and commercially viable approach for bone regeneration, offering significant potential for clinical applications.

Tissue Perfusion and Biomarkers Assessment Following Root Coverage Procedures.

To assess tissue perfusion changes and wound healing biomarker levels after root coverage procedures with coronally advanced flap in combination with the cross-linked xenogeneic collagen matrix (CCMX), loaded either with a placebo or recombinant human platelet-derived growth factor-BB (rhPDGF). This study was designed as a secondary analysis from a previously published clinical trial, and it assessed the tissue perfusion changes over 6 months around multiple gingival recession defects, treated with either with CCMX alone (control) or with CCMX + rhPDGF (test). High frequency Doppler ultrasonography (HFUS) scans were obtained at sites of interest at baseline, 2 weeks, 3 months, and 6 months after surgery. Dynamic tissue perfusion measurements (DTPMs) were performed at the midfacial, interproximal, and transverse aspects of the teeth by an operator, blinded to treatment allocation, using a software package. The expression of different wound healing biomarkers from the gingival crevicular fluid was also assessed. The regression analyses showed similar tissue perfusion changes between the two groups throughout the majority of the 6 months. DTPMs at 2 weeks showed the test group to have significantly higher perfusion relief intensity (pRI, p < 0.001), mean perfused area (pA, p < 0.001), mean blood flow intensity (FImean, p = 0.021), and total blood flow intensity (FItot, p = 0.021) at the graft region of interest (ROI) compared to control sites. The test sites also exhibited significantly greater pA (p = 0.033) and blood flow intensity "blue" (FIblue, meaning flow away from the transducer, p = 0.035) at the level of the flap compared to the control sites. At 2 weeks, FIblue of the graft was directly correlated with the final mean root coverage (p = 0.008) and complete root coverage (p = 0.003). FImean and FItot of the graft exhibited a direct correlation with volume gain at 6 months (p = 0.031 for both parameters). The final GT gain was correlated to the early DTPMs (pA and FIblue) of the graft and the flap. The two groups exhibited different expressions of IL-1β, PDFG-BB, and VEGF over 3 months, with the 1-week levels of PDGF-BB that were associated with time to recovery. HFUS allowed exquisite assessment of tissue perfusion occurring at the entire surgical reconstructive regions and also within the flap and the graft. Sites treated with CCMX + rhPDGF exhibited higher DTPMs, primarily within the graft and flap ROIs at the 2-week timepoint compared to sites augmented with CCMX + saline. Early DTPMs at the graft and flap ROIs showed associations with PROMs and the final clinical outcomes. ClinicalTrials.gov: NCT04462237.

Biotechnological Phytocomplex of Zanthoxylum piperitum (L.) DC. Enhances Collagen Biosynthesis In Vitro and Improves Skin Elasticity In Vivo.

Background:Zanthoxylum piperitum (L.) DC., commonly known as Japanese pepper, is a deciduous shrub native to East Asia. Its berries are widely used as a spice, known for imparting a distinctive, tingly numbing sensation. Biologically, Z. piperitum has antimicrobial, antioxidant, and anti-inflammatory properties, and it is studied for its potential benefits in pain relief and digestive health. This study proposed a novel biotechnological Z. piperitum phytocomplex (ZPP) obtained by plant cell culture for skin health, specifically targeting collagen synthesis, extracellular matrix stability, and resilience against cellular stress. Given the bioactivity of Z. piperitum, we aimed to analyze its efficacy as a sustainable alternative for skin-supportive applications in cosmetics and supplements. Methods: ZPP was produced through stable plant cell cultures, yielding a lignan-rich (3.02% w/w) phytocomplex. Human fibroblasts (HFFs) were treated with varying ZPP concentrations to assess cellular viability, collagen metabolism, and ECM-related enzyme activities, both under normal and cell stress conditions. The in vivo assessment was performed by measuring biophysical skin parameters such as hydration, elasticity, and roughness in female volunteers for a period of six weeks. Results: In vitro, ZPP exhibited non-cytotoxicity at all concentrations tested. Under hyperosmotic stress, ZPP reduced cellular damage, suggesting enhanced resilience. ZPP upregulated lysyl oxidase (LOX) protein levels, critical for collagen cross-linking and ECM stability, with protective effects observed under oxidative/inflammatory conditions. Additionally, ZPP selectively inhibited collagenase, attenuating collagen breakdown, though antioxidant activity was modest. In vivo evaluation highlighted improved skin hydration, elasticity, and roughness. Conclusions: ZPP shows promise as a biotechnological agent for skin health, particularly in supporting collagen integrity, ECM stabilization, and cellular resilience under stress. While further studies are needed to explore its full efficacy, especially for aging and environmentally stressed skin, these findings highlight ZPP's potential as a new ingredient for cosmetic formulations aimed at skin care and the treatment of alterations caused by aging or environmental conditions.

Topography-guided, patterned, customized corneal crosslinking for non-invasive astigmatism correction.

To propose and evaluate a novel, non-invasive approach for enduring corneal astigmatism correction based on topography-guided, patterned, customized riboflavin-ultraviolet A corneal collagen crosslinking (CXL). Astigmatism was modelled on both eyes of rabbits. A randomly selected eye of each rabbit was treated by the proposed CXL procedure with another eye as control. The proposed procedure was performed by a self-built intelligent platform through delivering ultraviolet A lattice in a refined and patterned manner, based on pre-operative corneal topography. The long-term effectiveness, stability, and safety were investigated for 180 days, with topographic measurements, anterior segment optical coherence tomography (AS-OCT), and in vivo corneal confocal microscopy (IVCM). Spatially selective demarcation lines in AS-OCT images and trabecular patterned hyperdense structure with abundant needle-like processes in IVCM images were detected in the CXL eyes, revealing spatially selective crosslinking. Reductions of astigmatic magnitude (in the steep axis: 0.46 ± 0.28 vs. 2.15 ± 0.58 dioptres, P < 0.001) and high order aberration (0.38 ± 0.18 vs. 0.59 ± 0.19, P = 0.009) with increase of visual strehl ratio (0.21 ± 0.06 vs. 0.13 ± 0.03, P < 0.001) were found in the CXL eyes after CXL and maintained for 180 days, compared to inconspicuous changes in the control eyes. No obvious opacity and inflammation were observed in the CXL eyes, and transient loss of endothelial cells in the treated area was recovered in the subsequent visit. The proposed novel, non-invasive approach safely fulfilled corneal astigmatism correction with visual quality improvement as well as a decrease in high-order aberration.

Effects of Aging on Intramuscular Collagen-Related Factors After Injury to Mouse Tibialis Anterior Muscle.

Collagen I is the most abundant type of intramuscular collagen. Lysyl oxidase promotes collagen cross-link formation, which helps stabilize the extracellular matrix. Furthermore, matrix metalloproteinases, responsible for collagen degradation, maintain typical muscle structure and function through remodeling. Although it is well known that aging leads to delayed recovery of muscle fibers, the impact of aging on the remodeling of intramuscular collagen is not well understood. In this study, we investigated the impact of aging on collagen remodeling during muscle injury recovery using young and old mouse models. Muscle injury was induced in the right tibialis anterior (TA) muscle of male C57BL/6J mice [aged 21 weeks (young) and 92 weeks (old)] using intramuscular cardiotoxin injection, with the left TA serving as a sham with saline injection. Following a one-week recovery period, aging was found to delay the recovery of the fiber cross-sectional area. The intensity and area of immunoreactivity for collagen I were significantly increased in old mice compared to young mice post-injury. Additionally, Lox expression and the number of LOX (+) cells in the extracellular matrix significantly increased in old mice compared to young mice post-injury. Furthermore, Mmp9 and MMP9 expression levels after muscle injury were higher in old mice than in young mice. These results suggest that muscle injury in old mice can lead to increased collagen I accumulation, enhanced collagen cross-link formation, and elevated MMP9 expression compared to young mice.

Impact of High Glucose on Bone Collagenous Matrix Composition, Structure, and Organization: An Integrative Analysis Using an Ex Vivo Model.

Diabetes mellitus is a widespread metabolic disorder linked to numerous systemic complications, including adverse effects on skeletal health, such as increased bone fragility and fracture risk. Emerging evidence suggests that high glucose may disrupt the extracellular matrix (ECM) of bone, potentially altering its composition and organization. Collagen, the primary organic component of the ECM, is critical for maintaining structural integrity and biomechanical properties. However, definitive evidence and a comprehensive understanding of the molecular mechanisms through which high glucose impacts the ECM and collagen remain elusive. This study employed an ex vivo embryonic chicken femur model to investigate the effects of high glucose on the collagenous matrix. A comprehensive approach integrating histological evaluation, histomorphometry, ATR-FTIR spectroscopy, and proteomics was adopted to unravel structural, biochemical, and molecular changes in the ECM. Histomorphometric analysis revealed disrupted collagen fibril architecture, characterized by altered fibril diameter, alignment, and spatial organization. ATR-FTIR spectroscopy highlighted biochemical modifications, including non-enzymatic glycation that impaired collagen crosslinking and reduced matrix integrity. Proteomic profiling unveiled significant alterations in ECM composition and function, including downregulation of key collagen crosslinking enzymes and upregulation of inflammatory and coagulation pathways. High glucose profoundly disrupts the collagenous matrix of bone, weakening its structural integrity and organization. These findings emphasize the critical impact of high glucose environments on extracellular matrix composition and bone quality, offering insights into the mechanisms behind diabetic bone fragility and guiding future research toward targeted therapeutic strategies.

Collagen turnover during cervical remodeling involves both intracellular and extracellular collagen degradation pathways.

Reproductive success requires accurately timed remodeling of the cervix to orchestrate the maintenance of pregnancy, the process of labor, and birth. Prior work in mice established that a combination of continuous turnover of fibrillar collagen and reduced formation of collagen cross-links allows for the gradual increase in tissue compliance and delivery of the fetus during labor. However, the mechanism for continuous collagen degradation to ensure turnover during cervical remodeling is still unknown. This study demonstrates the functional role of extracellular and intracellular collagen degradative pathways in two different settings of cervical remodeling: physiological term remodeling and inflammation-mediated premature remodeling. Extracellular collagen degradation is achieved by the activity of fibroblast-derived matrix metalloproteases MMP14, MMP2, and fibroblast activation protein (FAP). In parallel, we demonstrate the function of an intracellular collagen degradative pathway in fibroblast cells mediated by the collagen endocytic mannose receptor type-2 (MRC2). These pathways appear to be functionally redundant as loss of MRC2 does not obstruct collagen turnover or cervical function in pregnancy. While both extracellular and intracellular pathways are also utilized in inflammation-mediated premature cervical remodeling, the extracellular collagen degradation pathway uniquely employs fibroblast and immune-cell derived proteases. In sum, these findings identify the dual utilization of two distinct degradative pathways as a failsafe mechanism to achieve continuous collagen turnover in the cervix, thereby allowing dynamic shifts in cervical tissue mechanics and function.

The effects of type 1 and type 2 diabetes mellitus on bone health in chronic kidney disease.

Fracture is an under-recognized but common complication of diabetes mellitus, with an incidence approaching twofold in type 2 diabetes mellitus (T2DM) and up to sevenfold in type 1 diabetes mellitus (T1DM) compared with that in the general population. Both T1DM and T2DM induce chronic hyperglycaemia, leading to the accumulation of advanced glycosylation end products that affect osteoblast function, increased collagen crosslinking and a senescence phenotype promoting inflammation. Together with an increased incidence of microvascular disease and an increased risk of vitamin D deficiency, these factors reduce bone quality, thereby increasing bone fragility. In T1DM, reduced anabolic stimuli as well as the presence of autoimmune conditions might also contribute to reduced bone mass and increased fragility. Diabetes mellitus is the most common cause of kidney failure, and fracture risk is exacerbated when chronic kidney disease (CKD)-related mineral and bone disorders are superimposed on diabetic changes. Microvascular pathology, cortical thinning and trabecular deterioration are particularly prominent in patients with T1DM and CKD, who suffer more fragility fractures than do other patients with CKD. This Review explores the pathophysiology of bone fragility in patients with diabetes mellitus and CKD and discusses techniques to predict fracture and pharmacotherapy that might reduce fracture risk.

Integrating Corneal Collagen Crosslinking with Refractive Procedures (LASIK and PRK): A Comprehensive Review

Corneal collagen crosslinking is primarily carried out as a treatment modality for the management of corneal ectasias such as keratoconus, keratoglobus, pellucid marginal degeneration etc, as well as for the management of post refractive surgery corneal ectasias. However, it has evolved into a tool to strengthen the cornea in patients with borderline topography, who desire spectacle independence. This combined technique aims to enhance corneal strength and stability while maintaining visual acuity. However, careful patient selection, precise surgical planning, and understanding the biomechanical effects of crosslinking on the refractive outcome are essential to optimize the results. This article reviews the current evidence, risks, and considerations of simultaneous corneal collagen crosslinking and refractive surgery, highlighting its role in modern corneal and refractive surgery practices.

Clinical experience with denosumab discontinuation.

Discontinuing denosumab (DMAb) rapidly decreases bone mineral density (BMD) and increases the risk of multiple vertebral fractures. We wanted to examine if the recommendation stated in the ECTS position paper on DMAb discontinuation can prevent the bone loss in a clinical setting. We conducted a retrospective cohort study based on medical records of patients referred for DMAb discontinuation. We administered zoledronate (ZOL) 6 months after the last DMAb injection and 3, 6, 12, and 24 months thereafter if p-C-terminal collagen crosslinks (CTX) increased above 0.5 μg/l or BMD decreased (≥ 5% at the hip, ≥ 3% at the spine) at months 12 and 24. We included 66 women and men discontinuing DMAb after a mean treatment duration of 6.7 ± 2.7 (mean ± SD) years. BMD decreased 12 months after the initial ZOL treatment by 2.5 ± 4.2% and 1.9 ± 2.5% at the LS and TH, respectively (n = 44) (p ≤ 0.001 for all). There was no significant change in FNBMD (0.0 ± 5.1) (p > 0.05). No significant change in BMD was seen from month 12 to month 24 at any site (p > 0.05 for all). Thirty percent and twenty-two percent of patients experienced flu-like symptoms after the first and second ZOL infusion. No fractures occurred during the study period. Adhering to the recommendation in the ECTS position statement, a mean of 3 infusions of ZOL limited the bone loss 12 and 24 months after DMAb discontinuation, thereby preserving most of the BMD gained during DMAb treatment. The frequent occurrence of flu-like symptoms after ZOL proves to be a challenge, showing that routine prophylaxis against acute phase responses should be considered in patients treated with ZOL after discontinuing DMAb.

Kidney function, bone health, and vascular calcifications in patients with CKD II - IV: A 2 - 3 year prospective study with bone biopsies.

Patients with chronic kidney disease (CKD) have serum, bone, and vascular abnormalities presenting as chronic kidney disease-mineral bone disorder (CKD-MBD) syndrome. This study sought to identify the parameters with the greatest relative impact on progression of CKD-MBD abnormalities. This prospective study measured 237 parameters including serum markers, clinical variables, dual-energy X-ray absorptiometry (DXA) measurements, vascular calcifications, and histomorphometric results from bone samples obtained at baseline and after 2-3 years. Relative impact of these parameters on kidney function, bone changes, and vascular calcification were assessed using machine learning, a subset of artificial intelligence analyses. Baseline estimated glomerular filtration rate (eGFR) values ranged from 18 to 70 mL/min and declined in 52% of subjects by at least 3.3% annually during the study. These declines in eGFR were associated with changes in specific serum markers, bone quantity decreases, and bone quality alterations, but not with arterial calcifications. Arterial calcifications were associated with collagen crosslinking heterogeneity, serum phosphorus, diuretics and atorvastatin treatment, but not with kidney function. Baseline collagen crosslinking heterogeneity was an important factor impacting progression of coronary, but not aortic calcification. Baseline serum phosphorus was a factor primarily associated with progression of aortic calcification. Machine learning revealed specific bone and vascular abnormalities occurring early during loss of kidney function. Bone, vascular, blood, medication use, and other parameters were identified impacting the presence and progression of arterial calcification and altering bone quality and quantity in this understudied patient population. Serum phosphorus levels considered normal impacted progression of arterial calcification. Identification of these parameters and their relative importance enhances our understanding of CKD progression and should improve patient care.

Use of Photoreactive Riboflavin and Blue Light Irradiation in Improving Dentin Bonding-Multifaceted Evaluation.

Recently, photoactivated riboflavin (RF) treatments have been approved to improve resin-dentin bonding by enhancing dentinal collagen crosslinking. This study aimed to evaluate whether RF activated by blue light (BL, 450 nm) strengthens the collagen matrix, increases resistance to enzymatic degradation, and improves adhesion as effectively as ultraviolet A (UVA, 375 nm) activation. Six groups were examined: control (no treatment); RF0.1UV2 (0.1% RF with 2 min of UVA irradiation); RF0.1BL1, RF0.1BL2, RF1BL1, and RF1BL2 (0.1% and 1% RF with 1 or 2 min of BL irradiation). The effects of RF/BL on collagen crosslinking were validated by gel electrophoresis. A nanoindentation test showed that both RF/UVA and RF/BL treatments enhanced the elastic modulus and nanohardness of demineralized dentin. A zymography assay using collagen extracted from demineralized dentin also revealed significant matrix metalloproteinase-2 inhibition across all RF treatments. Microtensile bond strength (µTBS) tests conducted both post-treatment and after 7-day enzymatic degradation showed that three RF0.1 groups (RF0.1UV2, RF0.1BL1, and RF0.1BL2) maintained high µTBS values after degradation, while RF0.1BL1 generated a significantly thicker hybrid layer compared to other groups. These findings suggest that RF/BL is as effective as RF/UVA in crosslinking dentinal collagen and resisting enzymatic degradation, with 0.1% RF proving superior to 1% RF in enhancing dentin bonding.

Evaluation of corneal epithelial changes after corneal collagen cross-linking by using anterior segment optical coherence tomography

Background The thickness of the corneal epithelium can be precisely measured using anterior segment optical coherence tomography (AS-OCT). Aim This study aimed to conduct an AS-OCT evaluation of changes in the corneal epithelial thickness following collagen cross-linking (CXL). Patient and methods This prospective interventional study utilized 23 eyes from 13 cases who underwent treatment for progressive keratoconus (KC) with epi-off corneal CXL according to the Dresden’s Protocol. Results After 6 months postoperative the central minimum epithelial thickness (0.0–2.0 mm) showed a statistically significant increase, while the mid-peripheral (5.0–7.0 mm) showed a statistically significant decrease compared with the preoperative level. The central average epithelial thickness (0.0–2.0 mm) showed statistically nonsignificant increase, while the mid-peripheral and peripheral (5.0–7.0, 7.0–9.0 mm) showed a statistically significant decrease in comparison to the level before the operation. At 6 months postoperative, a decrease in Mean k was associated with statistically significant elevation in average central and paracentral epithelial thickness (0.0–2.0, 2.0–5.0 mm) as compared with the preoperative level (negative correlation). At 6 months postoperative, reduction in thinnest pachymetry was associated with statistically significant increase in central and paracentral average epithelial thickness (0.0–2.0, 2.0–5.0 mm) (negative correlation) as compared with the preoperative and 3 months postoperative. Conclusions With AS-OCT, it is simple to track changes in the epithelium over time. Epithelial remodeling occurs after CXL in the areas of protrusion and thinning. The thickness of the epithelium is greatest at the cone’s base and diminishes as one moves away from it.

Effects of low phosphorus diets on phosphorus balance and plasma concentrations of 25-hydroxyvitamin D3, and carboxy-terminal collagen crosslinks during the transition period in dairy cows.

Our aim was to determine the effects of P intake on P balance, serum parathyroid hormone (PTH) levels and bone resorption during the final 4 weeks prepartum and the first 8 weeks of lactation. Sixty pregnant multiparous Holstein Friesian dairy cows were assigned to a randomized block design with repeated measurements and dietary treatments arranged according to a 2 × 2 factorial design. The experimental diets contained 3.6 (high phosphorus, HP) or 2.2 (low phosphorus, LP) g P/kg DM during the dry period (Dry-HP and Dry-LP, respectively) and 3.8 or 2.9 g P/kg DM during 56 d after calving (Lac-HP and Lac-LP, respectively). The level of dietary P, expressed as g/kg DM, of Dry-LP was 18% greater than recommended by the Dutch Central Bureau for Livestock feeding, while the P content of Lac-LP was, across the 8 wks of lactation, 24% lower than recommended. Both P intake and fecal P excretion decreased in the dry period to increase again in subsequent lactation. Cows fed high dietary P excreted more P in the feces than cows fed low dietary P pre- and postpartum. Cows in both Dry-HP and Dry-LP were in positive P balance in the dry period. Cows in both Lac-LP and Lac-HP were in negative P balance after calving, with the negative P balance being more pronounced in Lac-LP than in Lac-HP. Serum concentrations of PTH, and apparent total-tract OM and NDF digestibility, were neither affected by any 2-way or 3-way interaction between time of sampling and dietary treatments nor by the P concentration of the experimental diets during the pre- and postpartum period. Before calving, serum carboxy-terminal collagen crosslinks (CTX) concentrations were basically similar between Dry-HP and Dry-LP. After calving, serum CTX concentrations increased, with a more pronounced increase when Lac-LP was fed compared with Lac-HP. The results suggest that when feeding diets containing low P (2.9 g/kg DM) postpartum, cows excreted less P in the feces than at recommended dietary P (3.8 g P/kg DM) without negative impact on OM and NDF digestibility. The increase in serum CTX concentrations, without increasing serum PTH concentrations upon feeding low P, indicates a prominent role of bone resorption to meet P demands in the first 8 weeks postpartum. The present trial focused on the final 4 weeks of gestation and the subsequent 8 weeks of lactation, but long-term effects of low dietary P during early lactation on serum PTH and on bone P dynamics in mid and late lactation need to be further investigated.

Coronally Advanced Flap with a Xenogeneic Collagen Matrix or a rhPDGF-BB-regenerative approach for Bilateral Multiple Gingival Recessions: A Split-mouth Clinical Feasibility Study.

This split-mouth trial investigated the efficacy of treating bilateral gingival recessions with either a xenogeneic cross-linked collagen matrix (CCM), or recombinant human platelet derived growth factor (rhPDGF-BB) with a bone allograft (AG). Ten patients were treated with the coronally advanced flap (CAF), either with a CCM, or rhPDGF-BB &#43; AG. The primary outcome was percentage of mean root coverage (mRC) at 12 months. Additional outcomes included clinical, volumetric, patient-reported outcome measures (PROMs) and ultrasonographic assessment of gingival thickness (GT) and position of the buccal bone (uBD). At 12 months, both groups showed significant improvements, with a mRC of 78.6% in the CCM group, and 82.3% for the rhPDGF-BB &#43; AG sites. 3D analysis of both groups showed comparable volumetric gain. CCM-treated sites displayed higher ultrasonographic echogenicity in GT (p<.01) than rhPDGF-BB &#43; AG sites. The rhPDGF-BB &#43; AG group showed greater reduction in the buccal bone dehiscence (mean 2.03 mm, p<0.01), less swelling during the first three days, and slighty greater mean root coverage. CCM and rhPDGF-BB &#43; AG showed to be effective in the treating multiple adjacent gingival recessions. CCM promotes greater gain in gingival thickness, while rhPDGF-BB &#43; AG resulted in a significantly less buccal bone dehiscense.

Augmented silver sulfadiazine nanostructured lipid carriers impregnated collagen sponge for promoting burn wound healing.

Silver sulfadiazine (SSD) is a widely used antibacterial agent for burn wound treatment owing to its capability in re-epithelialization and wound healing. However, due to its low solubility, the need for an effective drug delivery system is mandatory. This study aimed to optimize SSD nanostructured lipid-based carriers (NLCs), incorporated in a collagen sponge form as an innovative topical dosage form for effective burn wound treatment. SSD-NLCs were prepared by applying Box-Behnken design and characterized in terms of particle size, zeta potential, and entrapment efficiency (EE). The optimized SSD-NLCs formula was selected and incorporated into a cross-linked collagen sponge and lyophilized for 24 h. The SSD-NLCs sponge morphological structure, porosity, swelling ratio, in vitro drug release profile and antibacterial activity were assessed. Furthermore, investigating the competitive inhibitory efficiency of SSD against para-aminobenzoic acid (PABA), the native ligand for the dihydropteroate synthetase enzyme based on the calculated binding free energy using the CB-Dock docking server was evaluated. Additionally, the wound healing activity and histopathological studies were evaluated on a second-degree burn wounds in a rat model. The optimized SSD-NLCs were spherical, possessing size of 115.69 ± 3.25 nm, EE% of 89.69 ± 1.36 % and a porosity of 71.22 %. Furthermore, the SSD-NLCs sponge showed an enhanced swelling ratio and improved antimicrobial activity compared to SSD. Finally, in vivo studies in rats showed that SSD-NLCs sponge are effective wound healing formulation owing to their ability to improve the quality of tissue regeneration without scars formation. Results showed that SSD-NLCs sponge can enhance the SSD efficacy in treatment of burn wounds. Further toxicological studies are still needed before clinical application.