Collagen Cross-linking Research Articles

Scleral collagen crosslinking as a promising direction of sclera-strengthening treatment of progressive myopia

The review presents recent research works on new technologies of scleral collagen crosslinking, a promising approach to sclerastrengthening treatment of progressive myopia. We assess the advantages and limitations of a number of experimental techniques of photochemical and medicinal crosslinking of the sclera, as well as donor tissue crosslinking aimed at optimizing the plastic material for sclera-strengthening surgery. Successful experiments and effective first clinical implementation results of the approach can be viewed as the basis for its further improvement and wider introduction of the technology into ophthalmological practice.

Evaluation of Collagen Dermal Filler with Lidocaine for the Correction of Nasolabial Folds: A Randomized, Double-Blind, Multicenter Clinical Trial.

Porcine-based dermal injectable collagen is effective for nasolabial fold correction. In the present study, a new dermal injectable collagen, incorporating a novel cross-linking technology and premixed with lidocaine, was introduced. The study aimed to determine the efficacy of the new dermal injectable collagen in improving bilateral nasolabial fold wrinkles, and reducing pain during injection. This prospective, double-blind, multicenter, parallel-group, randomized trial enrolled participants with moderate-to-severe bilateral nasolabial fold wrinkles from February 2019 to March 2021. Participants were randomly assigned to the test group (new dermal injectable collagen with lidocaine featuring a novel cross-linking technology) or control group (traditionally cross-linked dermal injectable collagen with lidocaine). Participants were monitored for adverse events (AEs), and for pain using the Thermometer Pain Scale (TPS) and a visual analog scale (VAS). Efficacy was measured using the Wrinkle Severity Rating Scale (WSRS) and the Global Aesthetic Improvement Scale (GAIS). On the poor or better sides, the 2 groups exhibited a significant decrease in WSRS scores at 4, 12, 24, and 36 weeks after treatment, compared to baseline WSRS scores (all, p < 0.05). Compared to the control group, the test group had a greater decrease in WSRS score (poor or better sides) at 12, 24, 36, and 52 weeks after treatment (all, p < 0.05). A similar observation was also found in the WSRS response rate and GAIS score of the 2 groups. VAS and TPS scores were not significantly different between the 2 groups (p > 0.05), indicating that pain reduction was similar in the 2 groups. All AEs were anticipated AEs associated with facial aesthetic injections, and most recovered within 0 to 30 days without sequelae. There were no differences in AEs between the 2 groups (all, p > 0.05). The new dermal injectable collagen with lidocaine exhibited better efficacy for correcting nasolabial fold wrinkles compared to the control group. Both relieved pain and produced only transient and tolerable AEs.

A sterile corneal perforation in a postpartum lactating mother after 10 years of CXL: A case report and review of literature

To report a case of corneal perforation following injury with a child’s finger in a postpartum lactating mother in a corneal collagen cross-linkage with 1% riboflavin (CXL)-treated eye. A 28-year-old-female presented to us with acute and severe ocular pain in the right eye to the emergency department. She gave history of CXL done 10 years back, and examination revealed central corneal perforation with a flat anterior chamber. We managed the case successfully with penetrating keratoplasty, followed by a glaucoma tube procedure for secondary glaucoma. CXL is the standard treatment for progressive keratoconus, and its long-term safety is well known. Corneal perforation as an adverse event following CXL has also been noted in a few case reports. This case emphasizes the need for close follow-up with serials documentation of corneal thickness and prompt intervention.

Pediatric keratoconus in a tertiary eye hospital in Eastern province, Saudi Arabia: Patient characteristics and management outcomes.

This study investigates pediatric keratoconus in a tertiary eye hospital in Eastern Province, Saudi Arabia, aiming to understand the presenting features and treatment outcomes in this high-prevalence region. The research addresses pediatric keratoconus clinical profile and management strategies. A retrospective cohort study was conducted from 2022 to 2023, reviewing medical records of pediatric keratoconus patients. Demographic data, clinical characteristics, risk factors, presenting symptoms, and treatment outcomes were recorded. Severity staging was performed based on Amsler-Krumeich's classification. The study included 218 eyes from 109 pediatric keratoconus patients, with 65% of male and 35% of female patients. Decreased vision was the most common symptom (92%), and risk factors included a family history of keratoconus (9%) and vernal keratoconjunctivitis (6%). Stage 1 was the most frequent in both age groups (<14 years and ≥ 14 years). Treatment strategies included corneal collagen cross-linking (CXL), hard contact lenses, corneal rings, deep anterior lamellar keratoplasty (DLK), and penetrating keratoplasty. Significant improvements were observed in visual acuity, refractive errors, and tomographic parameters following these interventions. This study provides valuable insights into pediatric keratoconus in Saudi Arabia, emphasizing the importance of early diagnosis and interventions for better outcomes. Larger, multicenter prospective studies are essential for a comprehensive understanding of pediatric keratoconus and its optimal management. The findings contribute to the knowledge base and guide future research to improve patient quality of life.

P4HA2 promotes proliferation, invasion, and metastasis through regulation of the PI3K/AKT signaling pathway in oral squamous cell carcinoma

Proline 4-hydroxylase 2 (P4HA2) is known for its hydroxylase activity, primarily involved in hydroxylating collagen precursors and promoting collagen cross-linking under physiological conditions. Although its overexpression influences a wide variety of malignant tumors' occurrence and development, its specific effects and mechanisms in oral squamous cell carcinoma (OSCC) remain unclear. This study focused on investigating the expression patterns, carcinogenic functions, and underlying mechanisms of P4HA2 in OSCC cells. Various databases, including TCGA, TIMER, UALCAN, GEPIA, and K-M plotter, along with paraffin-embedded samples, were used to ascertain P4HA2 expression in cancer and its correlation with clinicopathological features. P4HA2 knockdown and overexpression cell models were developed to assess its oncogenic roles and mechanisms. The results indicated that P4HA2 was overexpressed in OSCC and inversely correlated with patient survival. Knockdown of P4HA2 suppressed invasion, migration, and proliferation of OSCC cells both in vitro and in vivo, whereas overexpression of P4HA2 had the opposite effects. Mechanistically, the phosphorylation levels of the PI3K/AKT pathway were reduced following P4HA2 silencing. The study reveals that P4HA2 acts as a promising biomarker for predicting prognosis in OSCC and significantly affects metastasis, invasion, and proliferation of OSCC cells through the regulation of the PI3K/AKT signaling pathway.

EFFICACY OF TRANSEPITHELIAL ACCELERATED COLLAGEN CROSS LINKING IN STOPPING THE PROGRESSION OF KERATOCONUS.

Keratoconus is a progressive ectatic disease of the cornea leading to central corneal thinning, protrusion and permanent visual impairment in untreated cases. It is affecting young children with strong association to vernal keratoconjunctivitis a common disease of Asian countries. Corneal collagen cross linkage (CXL) is standard procedure to stop progression of keratoconus. In this research article we used trans-epithelial accelerated corneal cross-linking to check its efficacy in stopping the progression of disease as quick and safe procedure with less chances of complication than standard CXL protocol. The study was carried out in Khyber Teaching Hospital from November 2022-October 2023. The sample size calculated was 36 with sampling technique of non-probability consecutive convenience sampling method. The mean age of the patients was 19.157±3.53 years. Post corneal cross-linking, at 6 months follow-up showed that in 94.44% of the patients, no progression of keratoconus was noted. Improvement in vision was recorded in 44.44% of patients. A positive correlation was detected between pre- and post-treatment patients in visual acuity, keratometry and pachymetry. The trans-epithelial accelerated corneal collagen crosslinking is a safe and quick procedure for stopping the progression of keratoconus associated with less morbidity and complications.

Peripheral Biomarkers of Anorexia Nervosa: A Meta-Analysis.

The pathogenesis of anorexia nervosa (AN) has been hypothesized to involve several biological systems. However, reliable biomarkers for AN have yet to be established. This study was aimed to identify statistically significant and clinically meaningful peripheral biomarkers associated with AN. A systematic literature search was conducted to identify studies published in English from inception until 30 June 2022. We conducted two-level random-effects meta-analyses to examine the difference between AN and comparison groups across 52 distinct biomarkers and found that acylated ghrelin, adrenocorticotropic hormone (ACTH), carboxy-terminal collagen crosslinks (CTX), cholesterol, cortisol, des-acyl ghrelin, ghrelin, growth hormone (GH), obestatin, and soluble leptin receptor levels were significantly higher in cases of AN compared with those in non-AN controls. Conversely, C-reactive protein (CRP), CD3 positive, CD8, creatinine, estradiol, follicle-stimulating hormone (FSH), free thyroxine, free triiodothyronine, glucose, insulin, insulin-like growth factor 1 (IGF-1), leptin, luteinizing hormone, lymphocyte, and prolactin levels were significantly lower in AN compared with those in non-AN controls. Our findings indicate that peripheral biomarkers may be linked to the pathophysiology of AN, such as processes of adaptation to starvation. Scientific investigation into peripheral biomarkers may ultimately yield breakthroughs in personalized clinical care for AN.

Computational and Experimental Characterization of Aligned Collagen across Varied Crosslinking Degrees.

Collagen-based scaffolds have been widely used in tissue engineering. The alignment of collagen fibers and the degree of crosslinking in engineering tissue scaffolds significantly affect cell activity and scaffold stability. Changes in microarchitecture and crosslinking degree also impact the mechanical properties of collagen scaffolds. A clear understanding of the effects of collagen alignment and crosslinking degrees can help properly control these critical parameters for fabricating collagen scaffolds with desired mechanical properties. In this study, combined uniaxial mechanical testing and finite element method (FEM) were used to quantify the effects of fiber alignment and crosslinking degree on the mechanical properties of collagen threads. We have fabricated electrochemically aligned collagen (ELAC) and compared it with randomly distributed collagen at varying crosslinking degrees, which depend on genipin concentrations of 0.1% or 2% for crosslinking durations of 1, 4, and 24 h. Our results indicate that aligned collagen fibers and higher crosslinking degree contribute to a larger Young's modulus. Specifically, aligned fiber structure, compared to random collagen, significantly increases Young's modulus by 112.7% at a 25% crosslinking degree (0.1% (4 h), i.e., 0.1% genipin concentration with a crosslinking duration of 4 h). Moreover, the ELAC Young's modulus increased by 90.3% as the crosslinking degree doubled by changing the genipin concentration from 0.1% to 2% with the same 4 h crosslinking duration. Furthermore, verified computational models can predict mechanical properties based on specific crosslinking degrees and fiber alignments, which facilitate the controlled fabrication of collagen threads. This combined experimental and computational approach provides a systematic understanding of the interplay among fiber alignment, crosslinking parameters, and mechanical performance of collagen scaffolds. This work will enable the precise fabrication of collagen threads for desired tissue engineering performance, potentially advancing tissue engineering applications.

Dynamics of Corneal Swelling With Hypoosmolar Riboflavin After Induction During Corneal Collagen Crosslinking in Patients With Progressive Keratoconus.

To evaluate the rate of corneal swelling induced by hypoosmolar riboflavin in patients with progressive keratoconus (KCN) with corneal thickness <400 µm after the induction phase using riboflavin with 20% dextran during epithelium-off corneal crosslinking (CXL). Prospective, nonrandomized, single-center consecutive case series. Preoperative assessments included tomography, specular microscopy, and hysteresis. After epithelial debridement, riboflavin with 20% dextran (Photrexa Viscous; Glaukos, Burlington, MA) was applied at 2-min intervals during a 30-min induction phase. Eyes that dehydrated to a minimum corneal thickness (MCT) of <400 µm after induction (postinduction pachymetry) were recruited. Hypoosmolar riboflavin 0.146% (Photrexa; Glaukos) was used every 10 s to induce stromal swelling, with pachymetry performed every 30 s until the MCT was ≥400 µm (postswelling pachymetry). Corneal swelling rate was compared with variables using regression analysis. In 31 eyes of 31 patients, mean postinduction pachymetry was 338.4 ± 28.7 μm. Hypoosmolar riboflavin induced a postswelling pachymetry of 413.4 ± 15.0 μm over a mean of 5.2 ± 3.2 min, and the average stromal swelling rate was 10.3 ± 8.7 μm/30 s. All eyes reached a postswelling pachymetry MCT ≥400 µm and no cases were aborted. Eyes with highly severe KCN (Kmax >70 and Belin/Ambrosio enhanced ectasia display final D score >17) experienced quicker swelling (14.4 ± 12.8 μm/30 s and 14.9 ± 12.4 μm/30 s, respectively; P < 0.05 for both). A thicker postinduction pachymetry was moderately associated with a faster rate of swelling (rs = 0.389; P = 0.030). Hypoosmolar riboflavin 0.146% can be safely employed in thinner corneas, allowing for swelling to ≥400 µm for epithelium-off CXL. Associations between swelling rate, KCN severity, and postinduction pachymetry were determined, allowing for a more accurate prediction of procedure time during CXL.

Alveolar Ridge Preservation Using a Novel Species-Specific Collagen-Enriched Deproteinized Bovine Bone Mineral: Histological Evaluation of a Prospective Case Series.

In recent years, the significance of maintaining the alveolar ridge following tooth extractions has markedly increased. Alveolar ridge preservation (ARP) is a commonly utilized technique and a variety of bone substitute materials and biologics are applied in different combinations. For this purpose, a histological evaluation and the clinical necessity of subsequent guided bone regeneration (GBR) in delayed implantations were investigated in a prospective case series after ARP with a novel deproteinized bovine bone material (95%) in combination with a species-specific collagen (5%) (C-DBBM). Notably, block-form bone substitutes without porcine collagen are limited, and moreover, the availability of histological data on this material remains limited. Ten patients, each scheduled for tooth extraction and desiring future implantation, were included in this study. Following tooth extraction, ARP was performed using a block form of C-DBBM in conjunction with a double-folded bovine cross-linked collagen membrane (xCM). This membrane was openly exposed to the oral cavity and secured using a crisscross suture. After a healing period ranging from 130 to 319 days, guided trephine drilling was performed for implant insertion utilizing static computer-aided implant surgery (s-CAIS). Cores harvested from the area previously treated with ARP were histologically processed and examined. Guided bone regeneration (GBR) was not necessary for any of the implantations. Histological examination revealed the development of a lattice of cancellous bone trabeculae through appositional membranous osteogenesis at various stages surrounding C-DBBM granules as well as larger spongy or compact ossicles with minimal remnants. The clinical follow-up period ranged from 2.5 to 4.5 years, during which no biological or technical complications occurred. Within the limitations of this prospective case series, it can be concluded that ARP using this novel C-DBBM in combination with a bovine xCM could be a treatment option to avoid the need for subsequent GBR in delayed implantations with the opportunity of a bovine species-specific biomaterial chain.

Safety and Efficacy of Epithelium-Off Corneal Collagen Cross-Linking for the Treatment of Corneal Ectasia: A Report by the American Academy of Ophthalmology

To review the evidence on the safety and effectiveness of epithelium-off corneal collagen cross-linking (CXL) for the treatment of progressive corneal ectasia. A literature search of the PubMed database was most recently conducted in March 2024 with no date restrictions and limited to studies published in English. The search identified 359 citations that were reviewed in abstract form, and 43 of these were reviewed in full text. High-quality randomized clinical trials comparing epithelium-off CXL with conservative treatment in patients who have keratoconus (KCN) and post-refractive surgery ectasia were included. The panel deemed 6 articles to be of sufficient relevance for inclusion, and these were assessed for quality by the panel methodologist; 5 were rated level I, and 1 was rated level II. There were no level III studies. This analysis includes 6 prospective, randomized controlled trials that evaluated the use of epithelium-off CXL to treat progressive KCN (5 studies) and post-laser refractive surgery ectasia (1 study), with a mean postoperative follow-up of 2.4 years (range, 1-5 years). All studies showed a decreased progression rate in treated patients compared with controls. Improvement in the maximum keratometry (Kmax) value, corrected distance visual acuity (CDVA), and uncorrected distance visual acuity (UDVA) was observed in the treatment groups compared with control groups. A decrease in corneal thickness was observed in both groups but was greater in the CXL group. Complications were rare. Epithelium-off CXL is effective in reducing the progression of KCN and post-laser refractive surgery ectasia in most treated patients with an acceptable safety profile. Proprietary or commercial disclosure may be found after the references.

MiR-214–3p regulates Piezo1, lysyl oxidases and mitochondrial function in human cardiac fibroblasts

Cardiac fibroblasts are pivotal regulators of cardiac homeostasis and are essential in the repair of the heart after myocardial infarction (MI), but their function can also become dysregulated, leading to adverse cardiac remodelling involving both fibrosis and hypertrophy. MicroRNAs (miRNAs) are noncoding RNAs that target mRNAs to prevent their translation, with specific miRNAs showing differential expression and regulation in cardiovascular disease. Here, we show that miR-214–3p is enriched in the fibroblast fraction of the murine heart, and its levels are increased with cardiac remodelling associated with heart failure, or in the acute phase after experimental MI. Tandem mass tagging proteomics and in-silico network analyses were used to explore protein targets regulated by miR-214–3p in cultured human cardiac fibroblasts from multiple donors. Overexpression of miR-214–3p by miRNA mimics resulted in decreased expression and activity of the Piezo1 mechanosensitive cation channel, increased expression of the entire lysyl oxidase (LOX) family of collagen cross-linking enzymes, and decreased expression of an array of mitochondrial proteins, including mitofusin-2 (MFN2), resulting in mitochondrial dysfunction, as measured by citrate synthase and Seahorse mitochondrial respiration assays. Collectively, our data suggest that miR-214–3p is an important regulator of cardiac fibroblast phenotypes and functions key to cardiac remodelling, and that this miRNA represents a potential therapeutic target in cardiovascular disease.

Reinforcing the aneurysmal aorta by additional layering: old and new strategies to prevent rupture

Adventitial crosslinking is a method in current investigational stage for preventing the rupture of aortic aneurysms. It is based on the photochemical crosslinking of adventitial collagen by exposure to ultraviolet A radiation. Essentially, an adventitial top layer is generated that displays enhanced mechanical properties and imparts additional strength and stiffness to the aneurysmal wall. Looking back upon the history of aortic surgery during 1940s, the aortic film wrapping, then dubbed “cellophane wrapping”, also was a procedure employed for delaying the aneurysmal rupture. In principle, the two procedures are similar in that both result in laminar composites, although the top layers differ fundamentally from each other. This review discussed in some detail the use and clinical outcomes of the aortic wrapping with artificial films, also mentioning the contemporary procedures still grouped under this umbrella term. The focus of the review was a comparative view on two procedures, the aortic film wrapping and adventitial crosslinking. It was concluded that the methods are different in many aspects, including the mechanisms of action. In fact, the promoters of adventitial crosslinking were not aware of the prior existence of aortic film wrapping. However, the achievements of the classical wrapping, by now regarded as merely historical episodes, did not discard prior knowledge, but repurposed it in a process that led to innovative strategies.

Collagen-β-cyclodextrin hydrogels for advanced wound dressings: super-swelling, antibacterial action, inflammation modulation, and controlled drug release

A key strategy in enhancing the efficacy of collagen-based hydrogels involves incorporating polysaccharides, which have shown great promise for wound healing. In this study, semi-interpenetrating polymeric network (semi-IPN) hydrogels comprised of collagen (Col) with the macrocyclic oligosaccharide β-cyclodextrin (β-CD) (20–80 wt.%) were synthesised. Fourier-transform infrared (FTIR) spectroscopy confirmed the successful fabrication of these Col/β-CD hydrogels, evidenced by the presence of characteristic absorption bands, including the urea bond band at ∼1740 cm−1, related with collagen crosslinking. Higher β-CD content was associated with increased crosslinking, higher swelling, and faster gelation. The β-CD content directly influenced the morphology and semi-crystallinity. All Col/β-CD hydrogels displayed superabsorbent properties, enhanced thermal stability, and exhibited slow degradation rates. Mechanical properties were significantly improved with contents higher than β-CD 40 wt.%. These hydrogels inhibited the growth of Escherichia coli bacteria and facilitated the controlled release of agents, such as malachite green, methylene blue, and ketorolac. The chemical composition of the Col/β-CD hydrogels did not induce cytotoxic effects on monocytes and fibroblast cells. Instead, they actively promoted cellular metabolic activity, encouraging cell growth and proliferation. Moreover, cell signalling modulation was observed, leading to changes in the expression of TNF-α and IL-10 cytokines. In summary, the results of this research indicate that these novel hydrogels possess multifunctional characteristics, including biocompatibility, super-swelling capacity, good thermal, hydrolytic, and enzymatic degradation resistance, antibacterial activity, inflammation modulation, and the ability to be used for controlled delivery of therapeutic agents, indicating high potential for application in advanced wound dressings.

A Standardized Protocol of Simultaneous Transepithelial Phototherapeutic Keratectomy (PTK) Followed by Corneal Collagen Crosslinking for Keratoconus.

To report outcomes in patients with progressive keratoconus who underwent a standardized protocol of transepithelial phototherapeutic keratectomy (t-PTK) laser followed by accelerated corneal collagen crosslinking (CXL). All patients with progressive keratoconus undergoing our protocol at a London clinic between 2019 and 2023 were included. The protocol involved t-PTK at 58-μm central ablation depth at a 9-mm treatment zone on the Schwind Amaris 1050RS platform. Preoperative K readings of 43.0D (both K1 and K2) were inputted for all cases. Patients then underwent CXL with a pulsed-light accelerated protocol (30 mW/cm2 for 8 minutes of UVA exposure time with 1 second on/1 second off). Seventy-nine eyes from 55 patients were included with an average follow-up of 12 months (range 6-24 months). Both mean uncorrected distance visual acuity (UDVA) and best spectacle-corrected visual acuity improved significantly from 0.42 preoperatively to 0.29 postoperatively (P < 0.01) and 0.11 to 0.06 postoperatively (P < 0.01), respectively. The refractive cylinder reduced significantly from -3.07D to -2.63D (P < 0.05). The mean Km improved from 46.15D to 45.44D (P < 0.01) and mean Kmax from 54.03D to 52.52D (P < 0.01). 77% of eyes (n = 61) exhibited Kmax improvement postoperatively, and 56% showed an improvement in UDVA (n = 44). 16% (n = 13) had worsening of vision, but of these, only 1 patient had visual loss of more than 2 lines. No eyes had corneal haze reported at the final follow-up, and none required additional treatment. This standardized simultaneous t-PTK and CXL protocol is safe and effective for the treatment of progressive keratoconus, providing visual, refractive, and topographic improvements.

The impact of interrupted corneal collagen crosslinking (CXL) treatment

PurposeTo evaluate progression of keratoconus in patients where CXL treatment was interrupted due to insufficient swelling of the cornea.MethodsA retrospective review was conducted of all patients with keratoconus diagnosis who underwent CXL at the Department of Ophthalmology, Örebro University Hospital (USÖ) during the years 2010–2017. In total 377 eyes of 280 patients were screened for inclusion. In 17 eyes (15 patients), the treatment was interrupted due to insufficient swelling of the cornea. Patient journals were reviewed and keratometry examinations were analysed for long-term progression.ResultsEleven eyes (nine patients) were included in the study. Five eyes showed no signs of progression after the interrupted CXL treatment. In one eye progression continued, however, first after a period of a number of years, indicating a delayed course of clinical progression.ConclusionThis study indicates that debridement of the corneal epithelium and riboflavin administration without intense UVA radiation may slow or arrest the progression of keratoconus, likely due to photosensitisation from ambient light.

An Effective Treatment for Progressive Keratoconus with Two-Year Outcomes: Accelerated Epithelium-on Corneal Cross-Linking

Purpose: Corneal collagen cross-linking is a surgical technique for progressive keratoconus. There are several technical modifications with varying clinical outcomes. This study aimed to evaluate the long-term outcomes of the accelerated epithelium-on collagen cross-linking. Design &amp; Methods: A retrospective study was performed on progressive keratoconus patients treated via the accelerated epithelium-on collagen cross-linking who completed the 24th-month follow-up. We included 111 eyes of 77 patients. Clinical variables, including visual acuity, aberrometry, topographic measurements, and refractive outcomes, were evaluated at the postoperative 12th and 24th months. Results: There was a significant improvement in postoperative visual acuity in 50.4% of the patients (p

Dynamics of collagen oxidation and cross linking in regenerating and irreversibly infarcted myocardium

In mammalian hearts myocardial infarction produces a permanent collagen-rich scar. Conversely, in zebrafish a collagen-rich scar forms but is completely resorbed as the myocardium regenerates. The formation of cross-links in collagen hinders its degradation but cross-linking has not been well characterized in zebrafish hearts. Here, a library of fluorescent probes to quantify collagen oxidation, the first step in collagen cross-link (CCL) formation, was developed. Myocardial injury in mice or zebrafish resulted in similar dynamics of collagen oxidation in the myocardium in the first month after injury. However, during this time, mature CCLs such as pyridinoline and deoxypyridinoline developed in the murine infarcts but not in the zebrafish hearts. High levels of newly oxidized collagen were still seen in murine scars with mature CCLs. These data suggest that fibrogenesis remains dynamic, even in mature scars, and that the absence of mature CCLs in zebrafish hearts may facilitate their ability to regenerate.

Periostin regulates lysyl oxidase through ERK1/2 MAPK-dependent serum response factor in activated cardiac fibroblasts.

Collagen crosslinking, mediated by lysyl oxidase, is an adaptive mechanism of the cardiac repair process initiated by cardiac fibroblasts postmyocardial injury. However, excessive crosslinking leads to cardiac wall stiffening, which impairs the contractile properties of the left ventricle and leads to heart failure. In this study, we investigated the role of periostin, a matricellular protein, in the regulation of lysyl oxidase in cardiac fibroblasts in response to angiotensin II and TGFβ1. Our results indicated that periostin silencing abolished the angiotensin II and TGFβ1-mediated upregulation of lysyl oxidase. Furthermore, the attenuation of periostin expression resulted in a notable reduction in the activity of lysyl oxidase. Downstream of periostin, ERK1/2 MAPK signaling was found to be activated, which in turn transcriptionally upregulates the serum response factor to facilitate the enhanced expression of lysyl oxidase. The periostin-lysyl oxidase association was also positively correlated in an in vivo rat model of myocardial infarction. The expression of periostin and lysyl oxidase was upregulated in the collagen-rich fibrotic scar tissue of the left ventricle. Remarkably, echocardiography data showed a reduction in the left ventricular wall movement, ejection fraction, and fractional shortening, indicative of enhanced stiffening of the cardiac wall. These findings shed light on the mechanistic role of periostin in the collagen crosslinking initiated by activated cardiac fibroblasts. Our findings signify periostin as a possible therapeutic target to reduce excessive collagen crosslinking that contributes to the structural remodeling associated with heart failure.

Elucidating the mechano-molecular dynamics of TRAP activity using CRISPR/Cas9 mediated fluorescent reporter mice

Osteoclasts are essential for bone remodeling by adapting their resorptive activity in response to their mechanical in vivo environment. However, the molecular mechanisms underlying this process remain unclear. Here, we demonstrated the role of tartrate-resistant acid phosphatase (TRAP, Acp5), a key enzyme secreted by osteoclasts, in bone remodeling and mechanosensitivity. Using CRISPR/Cas9 reporter mice, we demonstrated bone cell reporter (BCRIbsp/Acp5) mice feature fluorescent TRAP-deficient osteoclasts and examined their activity during mechanically driven trabecular bone remodeling. Although BCRIbsp/Acp5 mice exhibited trabecular bone impairments and reduced resorption capacity in vitro, RNA sequencing revealed unchanged levels of key osteoclast-associated genes such as Ctsk, Mmp9, and Calcr. These findings, in conjunction with serum carboxy-terminal collagen crosslinks (CTX) and in vivo mechanical loading outcomes collectively indicated an unaltered bone resorption capacity of osteoclasts in vivo. Furthermore, we demonstrated similar mechanoregulation during trabecular bone remodeling in BCRIbsp/Acp5 and wild-type (WT) mice. Hence, this study provides valuable insights into the dynamics of TRAP activity in the context of bone remodeling and mechanosensation.