Search Results (80)

This study characterized collagen remodeling in an electron-beam-sterilized porcine acellular dermal matrix (E-PADM) by evaluating host response kinetics during wound healing. E-PADM (n = 6 lots/time point) was implanted in an abdominal wall bridging defect in nonhuman primates (N = 24). Histological, immunohistochemical, and biochemical assessments were conducted. Pro-inflammatory tissue cytokines peaked 1 month post-implantation and subsided to baseline by 6 months. E-PADM-specific serum immunoglobulin G antibodies increased by 213-fold from baseline at 1 month, then decreased to <10-fold by 6–9 months. The mean percentage tissue area staining positively for matrix metalloproteinase-1 plateaued at 3 months (40.3 ± 16.9%), then subsided by 6 months (16.3 ± 11.1%); tissue inhibitor matrix metalloproteinase-1 content plateaued at 1 month (39.0 ± 14.3%), then subsided by 9 months (13.0 ± 8.8%). Mean E-PADM thickness (1.7 ± 0.2 mm pre-implant) increased at 3 months (2.9 ± 1.5 mm), then decreased by 9 months (1.9 ± 1.1; equivalent to pre-implant). Histology demonstrated mild inflammation between 1–3 months, then a peak in host tissue deposition, with ≈75%–100% E-PADM collagen turnover, and fibroblast infiltration and neovascularization between 3–6 months. Picrosirius red staining revealed that mature E-PADM collagen was replaced by host-associated neo-collagen by 6 months. E-PADM implantation induced wound healing, which drove dermal E-PADM collagen remodeling to native, functional fascia-like tissue at the implant site. Full article

The aim of the study was to compare tissue repair of incisions made using different microdissection electrocautery tips in an in vivo animal model. Skin incisions were made, including the subcutaneous tissue, in 30 adult Wistar rats using four types of instruments: a scalpel blade number 15, knife-type electrocautery, microdissection needle, and thin-cut electrode. The animals were divided into five groups based on the euthanasia time—24 h, 48 h, 72 h, 7 days, and 14 days. Each animal received four incisions, one with each type of instrument. Histological and histomorphometric analyses were performed using hematoxylin and eosin (HE) and Picrosirius red stains. Analysis of variance (ANOVA) showed that the type of dissector had no significant effect on type I collagen levels (p = 0.615), whereas the euthanasia time had a significant influence (p < 0.001). Estimated marginal means for type I collagen showed minimal variation among groups, ranging from 35.4% to 36.5%, suggesting limited clinical differences between instruments. These results indicate that while the choice of dissector has a limited impact on type I collagen deposition, time is a determining factor in the wound healing process. The thin-cut electrode enables incisions with tissue repair comparable to that of a number 15 scalpel, as it performs cutting, coagulation, and blending functions at lower temperatures. Full article

Androgens are emerging as important regulators of connective tissue remodeling, but current knowledge about their role in human fascia is still limited. This study examined the expression of the androgen receptor (AR) in human deep fascia and investigated the effects of dihydrotestosterone (DHT) on collagen production by fascial fibroblasts. Fascia lata and thoracolumbar fascia samples were collected from four adult donors (two male and two female). AR expression was assessed by immunohistochemistry and immunocytochemistry. Fascial fibroblasts were treated in vitro for 24 h with DHT at concentrations reflecting physiological levels: 0.4 ng/mL (female), 4 ng/mL (male average), and 10 ng/mL (high male dose). Collagen content was quantified using Picrosirius Red staining, and collagen I and III were evaluated using immunocytochemistry and image analysis, and were compared to an untreated control group. AR was detected in all samples. Low-dose DHT (0.4 ng/mL) significantly increased collagen I (4.80 ± 1.75%) and decreased collagen III (3.32 ± 0.46%) compared to controls (2.09 ± 0.91% and 10.46 ± 0.53%, respectively; p < 0.05). Higher DHT doses induced smaller or no significant changes in collagen subtype expression (e.g., 10 ng/mL: 2.03 ± 0.81% for collagen I, 8.49 ± 1.85% for collagen III). The results demonstrated that human fascia is hormonally responsive via AR, with DHT modulating matrix composition in a dose-dependent manner. The distinct effects at male and female levels may help explain gender differences in fascial stiffness and pain. Full article

The enzyme transglutaminase 2 (TG2) has an open conformation with transamidase activity which crosslinks matrix proteins contributing to fibrosis development. LDN-27219 promotes the closed conformation of TG2, which can enhance vasodilation, but its effects in renal tissue are unknown. We investigated whether LDN-27219 treatment affects albuminuria and markers of renal fibrosis as well as ex vivo vasodilatation. Male C57BL/6 mice (n = 48) underwent unilateral nephrectomy plus insertion of a deoxycorticosterone acetate pellet (DOCA group) or nephrectomy only (sham group). Both groups were randomized to intraperitoneal treatment with either LDN-27219 (8 mg/kg twice daily) or vehicle for 2 weeks. Urine albumin excretion was evaluated by metabolic cages. Kidney tissue fibrosis markers were assessed by qPCR and Western blotting, while the TG2 conformational state was evaluated using native gel electrophoresis. Collagen staining was performed using Picrosirius red and quantified under circularly polarized light. Mesenteric arteries were mounted in wire myographs for evaluation of vasorelaxation. DOCA mouse developed significant albuminuria (p < 0.001 vs. sham), but neither TG2 mRNA nor protein expression was upregulated in the kidney. However, the relative amount of TG2 in the closed conformation was higher in DOCA mice. LDN-27219 did not affect albuminuria, but LDN-27219-treated DOCA mice showed less urine production and less collagen staining than vehicle-treated DOCA mice. LDN-27219 did not affect TG2 mRNA or TG2 protein expression or mRNA of fibrosis markers. LDN-27219-treated mice had enhanced vasorelaxation to the nitric oxide donor sodium nitroprusside. In conclusion, LDN-27219 treatment in the one-kidney DOCA–salt model did not affect renal TG2 mRNA and protein expression or albuminuria but still exerted beneficial effects in terms of reduced kidney fibrosis and urine production in addition to enhanced vasodilatation. Full article

Chronic wound healing is a significant challenge in diabetes. Puerarin is an active compound extracted from the traditional Chinese medicine Pueraria lobata. Puerarin has been used in the treatment of diabetes and derives benefits from its antioxidant, anti-inflammatory, antibacterial, and pro-angiogenesis properties, but its efficacy is hampered by poor water solubility and bioavailability. In this study, we designed a polyvinyl alcohol (PVA)–borax–puerarin (BP) hydrogel system that self-assembled via boronic ester bonds. The BP hydrogel exhibited exceptional physical characteristics, including adaptability, injectability, plasticity, self-healing capabilities, and robust compressive strength, as well as good biocompatibility. In the chronic wound diabetic rats model, the BP hydrogel significantly accelerated wound healing, as evidenced by hematoxylin and eosin (HE) staining, as well as Masson and picrosirius red (PSR) staining. RNA–sequencing and multiple immunohistochemistry (mIHC) analyses revealed that the BP hydrogel exerts a therapeutic effect by modulating macrophage polarization, promoting angiogenesis, and regulating collagen remodeling. Our findings suggest that the BP hydrogel represents a promising wound dressing and holds great potential for clinical applications in acute and chronic wound management. Full article

Pregnancy presents specific metabolic demands, and disruption caused by a high-fat high-sugar diet (HFHSD) have been associated with significant complications, including maternal health risk, fetal developmental issues, and infertility. Obesity-related changes in the uterine tissues may contribute to these challenges. This study analyzed structural changes in the uterus and adipose tissue of pregnant rats on gestation day 22 fed an HFHSD using various staining techniques. Hematoxylin and eosin staining showed morphological changes in the adipose tissue and the uterine structure, including the lumen size and the thickness of the myometrium, endometrium, and perimetrium. The amount of collagen in the uterus was determined by PicroSirius red staining, while PAS-D staining was used to observe glycogen content. Key protein expressions, such as insulin and leptin receptors and UCP1 and UCP3, were analyzed by immunohistochemistry. The HFHSD promoted hypertrophy of visceral and gonadal adipocytes, suggesting metabolic alterations. By the end of pregnancy, a significant reduction in uterine lumen size was observed. Additionally, a decrease in insulin and higher leptin receptor expressions in the myometrium indicated significant physiological alteration. These findings offer insight into how an HFHSD affects uterine structure and function during late pregnancy but should be interpreted within the physiological context of gestation-related metabolic changes. Further research is needed to understand the functional consequences of these alterations on reproductive and metabolic health. Full article

During development, the remodelling of fibrillar components of the uterine extracellular matrix (ECM), mediated by the matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), plays an essential role in embryonic survival. Previously, we observed that in the plains viscacha (Lagostomus maximus), only caudal implantation sites (IS) contain viable embryos, whereas embryos at cranial and middle IS die and are reabsorbed. The objective of this study was to analyse the distribution and expression of key components of the endometrial ECM, including fibrillar collagens, MMPs 2 and 9, and TIMPs 1 and 2, in three uterine segments (US) of the non-pregnant adult viscachas. In sections from three US, we observed a significant craniocaudal increase in collagen fibres (Van Gieson and Picrosirius red staining) and elastic fibres (Verhoeff-Van Gieson trichrome staining), along with the immunolabelling levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 (immunohistochemistry). Zymography revealed similar gelatinolytic activity of MMP-2 in the three US but higher than the MMP-9 activity. However, MMP-9 activity in the caudal segment was significantly higher than that in the cranial and middle ones. These findings suggest that uterine ECM variations along the craniocaudal axis may contribute to uterine remodelling processes that regulate embryonic survival during gestation. Full article

South American camelids inhabit high-altitude environments characterized by hypoxia, influencing embryonic, fetal, and placental development. This study examined the term placenta morphology of alpacas (Vicugna pacos, N = 12) and the immunoexpression of antioxidant selenoproteins (SP). We hypothesize that the placenta of alpacas, adapted to high altitudes, has characteristics with other species also adapted to altitude. Placentas were paraffin-embedded, sectioned (3–5 µm), stained with hematoxylin–eosin (H&E), Masson’s trichrome, and picrosirius red, and analyzed via light and polarized light microscopy. The chorion showed simple cuboidal epithelium with binucleated cells, a subepithelial mesenchyme rich in blood capillaries (area: 124.90 ± 9.82 µm²), and type III collagen fibers. The chorionic villi measured 2740.22 ± 132.75 µm. The allantois contained a simple columnar epithelium and mesenchyme with type I collagen fibers. Immunohistochemistry localized SP-N, SP-P, Dio-3, and GPx-3 in the blood capillaries and mesenchymal tissue of the chorion but not in the allantois. These findings were compared to human and sheep placentas from different altitudes due to a lack of camelid data at low levels. The morphological features resembled adaptations to hypoxia observed in other species. This preliminary study suggests a potential role for selenoproteins in hypoxia adaptation, providing a basis for future functional studies. Full article

Recently, it has been reported that mesenchymal stem cell (MSC)-derived humoral factors promote skin wound healing. As these humoral factors are transiently stored in cytoplasm, we collected them as part of the cell extracts from MSCs (MSC-ext). This study aimed to investigate the effects of MSC-ext on skin wound healing. We examined the effects of MSC-ext on cell proliferation and migration. Additionally, the effect of MSC-ext on skin wound healing was evaluated using a mouse skin defect model. The MSC-ext enhanced the proliferation of dermal fibroblasts, epithelial cells, and endothelial cells. It also increased the number of migrating fibroblasts and epithelial cells. The skin defects treated with MSC-ext demonstrated rapid wound closure compared to those treated with phosphate-buffered saline. The MSC-ext group exhibited a thicker dermis, larger Picrosirius red-positive areas, and a higher number of Ki67-positive cells. Our results indicate that MSC-ext promotes the proliferation and/or migration of fibroblasts, epithelial cells, and endothelial cells, and enhances skin wound healing. This suggests the therapeutic potential of MSC-ext in treating skin defects as a novel cell-free treatment modality. Full article

Background/Objectives: The precise quantification of myocardial infarction is crucial for evaluating therapeutic strategies. We developed a robust, color-based semi-automatic algorithm capable of infarct region detection, isolation and quantification with four different histological staining techniques, and of the isolation and quantification of diffuse fibrosis in the heart. Methods: Our method is developed based on the color difference in the infarct and non-infarct regions after histological staining. Mouse cardiac tissues stained with Masson’s trichrome (MTS), hematoxylin and eosin (H&E), 2,3,5-Triphenyltetrazolium chloride and picrosirius red were included to demonstrate the performance of our method. Results: We demonstrate that our algorithm can effectively identify and produce a clear visualization of infarct tissue in the four staining techniques. Notably, the infarct region on an H&E-stained tissue section can be clearly visualized after processing. The MATLAB-based program we developed holds promise for infarct quantification. Additionally, our program can isolate and quantify diffuse fibrotic elements from an MTS-stained cardiac section, which suggests the algorithm’s potential for evaluating pathological cardiac fibrosis in diseased cardiac tissues. Conclusions: We demonstrate that this color-based algorithm is capable of accurately identifying, isolating and quantifying cardiac infarct regions with different staining techniques, as well as diffuse and patchy fibrosis in MTS-stained cardiac tissues. Full article

Background: Altered patterns of bile acids (BAs) are frequently present in liver fibrosis, and BAs function as signaling molecules to initiate inflammatory responses. Silybin meglumine (SLB-M) is widely used in treating various liver diseases including liver fibrosis. However, research on its effects on bile acid (BA) metabolism is limited. This study investigated the therapeutic effects of SLB-M on liver fibrosis and BA metabolism in a CCl₄-induced murine model. Methods: A murine liver fibrosis model was induced by CCl4. Fibrosis was evaluated using HE, picrosirius red, and Masson’s trichrome staining. Liver function was assessed by serum and hepatic biochemical markers. Bile acid (BA) metabolism was analyzed using LC-MS/MS. Bioinformatics analyses, including PPI network, GO, and KEGG pathway analyses, were employed to explore molecular mechanisms. Gene expression alterations in liver tissue were examined via qRT-PCR. Results: SLB-M treatment resulted in significant histological improvements in liver tissue, reducing collagen deposition and restoring liver architecture. Biochemically, SLB-M not only normalized serum liver enzyme levels (ALT, AST, TBA, and GGT) but also mitigated disruptions in both systemic and hepatic BA metabolism by increased unconjugated BAs like cholic acid and chenodeoxycholic acid but decreased conjugated BAs including taurocholic acid and taurodeoxycholic acid, compared to that in CCl₄-induced murine model. Notably, SLB-M efficiently improved the imbalance of BA homeostasis in liver caused by CCl₄ via activating Farnesoid X receptor. Conclusions: These findings underscore SLB-M decreased inflammatory response, reconstructed BA homeostasis possibly by regulating key pathways, and gene expressions in BA metabolism. Full article

Biomaterials and biopharmaceuticals for correcting large bone defects are a potential area of translational science. A new bioproduct, purified from snake venom and fibrinogen from buffalo blood, aroused interest in the repair of venous ulcers. Expanding potential uses, it has also been used to form biocomplexes in combination with bone grafts, associated with physical therapies or used alone. The aim of this preclinical study was to evaluate low-level laser photobiomodulation (PBM) in critical defects in the calvaria of rats filled with nanohydroxyapatite (NH) associated with the heterologous fibrin biopolymer (HFB). Sixty animals were used, divided into six groups (n = 10 each): G1 (NH); G2 (HFB); G3 (NH + HFB); G4 (NH + PBM); G5 (HFB + PBM); G6 (NH + HFB + PBM). PBM simultaneously used red (R) and infrared (IR) light emission, applied intraoperatively and twice a week, until the end of the experiment at 42 days. Microtomography, bone formation can be seen initially at the margins of the defect, more evident in G5. Microscopically, bone formation demonstrated immature and disorganized trabeculation at 14 days, with remnants of grafting materials. At 42 days, the percentage of new bone formed was higher in all groups, especially in G5 (HFB, 45.4 ± 3.82), with collagen fibers at a higher degree of maturation and yellowish-green color in the birefringence analysis with Picrosirius-red. Therefore, it is concluded that the HFB + PBM combination showed greater effectiveness in the repair process and presents potential for future clinical studies. Full article

Acute-phase serum amyloid A (SAA) can disrupt vascular homeostasis and is elevated in subjects with diabetes, cardiovascular disease, and rheumatoid arthritis. Cyclic nitroxides (e.g., Tempo) are a class of piperidines that inhibit oxidative stress and inflammation. This study examined whether 4-methoxy-Tempo (4-MetT) inhibits SAA-mediated vascular and renal dysfunction. Acetylcholine-mediated vascular relaxation and aortic guanosine-3′,5′-cyclic monophosphate (cGMP) levels both diminished in the presence of SAA. 4-MetT dose-dependently restored vascular function with corresponding increases in cGMP. Next, male ApoE-deficient mice were administered a vehicle (control, 100 µL PBS) or recombinant SAA (100 µL, 120 µg/mL) ± 4-MetT (at 15 mg/kg body weight via i.p. injection) with the nitroxide administered before (prophylaxis) or after (therapeutic) SAA. Kidney and hearts were harvested at 4 or 16 weeks post SAA administration. Renal inflammation increased 4 weeks after SAA treatment, as judged by the upregulation of IFN-γ and concomitant increases in iNOS, p38MAPK, and matrix metalloproteinase (MMP) activities and increased renal fibrosis (Picrosirius red staining) in the same kidneys. Aortic root lesions assessed at 16 weeks revealed that SAA enhanced lesion size (vs. control; p < 0.05), with plaque presenting with a diffuse fibrous cap (compared to the corresponding aortic root from control and 4-MetT groups). The extent of renal dysfunction and aortic lesion size was largely unchanged in 4-MetT-supplemented mice, although renal fibrosis diminished at 16 weeks, and aortic lesions presented with redistributed collagen networks. These outcomes indicate that SAA stimulates renal dysfunction through promoting the IFN-γ–iNOS–p38MAPK axis, manifesting as renal damage and enhanced atherosclerotic lesions, while supplementation with 4-MetT only affected some of these pathological changes. Full article

Tendon injury and healing involve significant changes to tissue biology and composition. Current techniques often require animal sacrifice or tissue destruction, limiting assessment of dynamic changes in tendons, including treatment response, disease development, rupture risk, and healing progression. Changes in tendon composition, such as altered collagen content, can significantly impact tendon mechanics and function. Analyses of compositional changes typically require ex vivo techniques with animal sacrifice or destruction of the tissue. In vivo evaluation of tendons is critical for longitudinal assessment. We hypothesize that photoacoustic ultrasound detects differences in collagen concentration throughout healing. We utilized photoacoustic ultrasound, a hybrid imaging modality that combines ultrasound and laser-induced photoacoustic signals to create detailed and high-resolution images of tendons, to identify its endogenous collagen composition. We correlated the photoacoustic signal to picrosirius red staining. The results show that the photoacoustic ultrasound-estimated collagen content in tendons correlates well with picrosirius red staining. This study demonstrates that photoacoustic ultrasound can assess injury-induced compositional changes within tendons and is the first study to image these targets in rat Achilles tendon in vivo. Full article

The evolution of biomaterials engineering allowed for the development of products that improve outcomes in the medical–dental field. Bioglasses have demonstrated the ability to either compose or replace different materials in dentistry. This study evaluated the cytotoxicity, biocompatibility, calcium deposition, and collagen maturation of 45S5 bioglass experimental paste and Bio-C Temp, compared to calcium hydroxide (Ca(OH)₂) paste. The 45S5 bioglass and Ca(OH)₂ powder were mixed with distilled water (ratio 2:1); Bio-C Temp is ready-for-use. Dental pulp cells were exposed to the materials’ extracts (1:2 and 1:4 dilutions; 24, 48, and 72 h) for MTT and live/dead analyses. Polyethylene tubes filled with the pastes, or left empty (control), were implanted on the dorsum of 16 rats. After 7 and 30 days (n = 8/period), the rats were euthanized and the specimens were processed for hematoxylin–eosin (H&E), von Kossa (vK), and picrosirius red (PSR) staining, or without staining for polarized light (PL) birefringence analysis. A statistical analysis was applied (p < 0.05). There was no difference in cell viability among Ca(OH)₂, 45S5 bioglass, and the control, across all periods and dilutions (p > 0.05), while Bio-C Temp was cytotoxic in all periods and dilutions compared to the control (p < 0.05). Regarding biocompatibility, there was a reduction in inflammation from 7 to 30 days for all groups, without significant differences among the groups for any period (p > 0.05). The fibrous capsules were thick for all groups at 7 days and thin at 30 days. All materials showed positive structures for vK and PL analysis. At 7 days, the control and 45S5 bioglass showed more immature collagen than the other groups (p < 0.05); at 30 days, 45S5 bioglass had more immature than mature collagen, different from the other groups (p < 0.05). In conclusion, Bio-C Temp presented cytotoxicity compared to the other materials, but the three pastes showed biocompatibility and induced calcium deposition. Additionally, the bioglass paste allowed for marked and continuous collagen proliferation. This study contributed to the development of new biomaterials and highlighted different methodologies for understanding the characteristics of medical–dental materials. Full article