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The southern catfish (Silurus meridionalis) is an economically important carnivorous freshwater fish in China. In this study, we compared the properties of skin collagen from southern catfish fed with raw food (RF) and cooked food (CF). The skin collagen yield in the RF group (8.66 ± 0.11%) was significantly higher than that of the CF group (8.00 ± 0.27%). SDS-PAGE, circular dichroism spectroscopy, and FTIR analyses revealed that the collagen extracted from southern catfish skin in both groups was type I collagen, with a unique triple helix structure and high purity. The thermal denaturation temperature of collagen in the RF group (35.20 ± 0.11 °C) was significantly higher than that of the CF group (34.51 ± 0.25 °C). The DPPH free radical scavenging rates were 68.30 ± 2.41% in the RF collagen and 61.78 ± 3.91% in the CF collagen, which was higher than that found in most fish collagen. Both the RF and CF groups had high ability to form fibrils in vitro. Under the same conditions, the CF group exhibited faster fibril formation and a thicker fibril diameter (p < 0.05). In addition, the RF group exhibited significantly higher expression of col1a1 compared to the CF group. These results indicated that feeding southern catfish raw food contributed to collagen production, and the collagen from these fish may have potential in biomaterial applications. [ABSTRACT FROM AUTHOR]

This study assessed the biocompatibility of two types of nanogold composites: fibronectin-gold (FN-Au) and collagen-gold (Col-Au). It consisted of three main parts: surface characterization, in vitro biocompatibility assessments, and animal models. To determine the structural and functional differences between the materials used in this study, atomic force microscopy, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectrophotometry were used to investigate their surface topography and functional groups. The F-actin staining, proliferation, migration, reactive oxygen species generation, platelet activation, and monocyte activation of mesenchymal stem cells (MSCs) cultured on the FN-Au and Col-Au nanocomposites were investigated to determine their biological and cellular behaviors. Additionally, animal biocompatibility experiments measured capsule formation and collagen deposition in female Sprague–Dawley rats. The results showed that MSCs responded better on the FN-Au and Col-AU nanocomposites than on the control (tissue culture polystyrene) or pure substances, attributed to their incorporation of an optimal Au concentration (12.2 ppm), which induced significant surface morphological changes, nano topography cues, and better biocompatibility. Moreover, neuronal, endothelial, bone, and adipose tissues demonstrated better differentiation ability on the FN-Au and Col-Au nanocomposites. Nanocomposites have a crucial role in tissue engineering and even vascular grafts. Finally, MSCs were demonstrated to effectively enhance the stability of the endothelial structure, indicating that they can be applied as promising alternatives to clinics in the future. [ABSTRACT FROM AUTHOR]

Acute and chronic liver failure are clinically significant conditions, and the artificial liver support system (ALSS) is emerging as a novel and effective approach for the clinical management of liver failure. Within this framework, scaffold materials occupy a pivotal position as integral components of the bioreactor. Elevating the performance capabilities of these scaffolds not only augments the therapeutic efficacy of the artificial liver but also lays the groundwork for refining and selecting large-scale hepatocyte culture models. In this study, we introduced a novel hepatocyte scaffold material designated as PET-COL, crafted by coating polyethylene terephthalate (PET) with collagen. This involved a sequence of modifications, including alkaline hydrolysis, EDC/NHS activation and crosslinking, as well as collagen conjugation. The physicochemical attributes of the scaffold were thoroughly characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), second harmonic generation (SHG), water contact angle measurements, and high-performance liquid chromatography–mass spectrometry (HPLC-MS). Furthermore, an investigation into the material's biological properties was conducted that encompassed SEM (HepaRG growth), fluorescence staining (assessment of cell viability), staining by trypan blue (HepaRG counting), CCK-8 (proliferation of cells), biochemical testing, and immunosorbent assay. Our findings revealed that collagen was covalently bonded to the PET surface, leading to a substantial enhancement in the material's hydrophilicity (p < 0.001). The quantity of collagen coating was determined to be precisely 33.30 μg per scaffold. Human liver progenitor HepaRG cells thrived on the PET-COL material. Compared with the untreated group, cell viability, albumin secretion, urea synthesis, and the expression levels of CYP3A4 and CPS1 increased significantly (p < 0.001), demonstrating remarkable biological vitality. The PET-COL scaffold, as developed in this study, holds immense potential for application in bioartificial livers. [ABSTRACT FROM AUTHOR]

Heat shock protein 47 (HSP47), also known as SERPINH1, functions as a collagen-specific molecular chaperone protein essential for the formation and stabilization of the collagen triple helix. Here, we delved into the regulatory pathways governed by HSP47, shedding light on collagen homeostasis. Our investigation revealed a significant reduction in HSP47 mRNA levels in the skin tissue of older mice as compared to their younger counterparts. The augmented expression of HSP47 employing lentivirus infection in fibroblasts resulted in an increased secretion of type I collagen. Intriguingly, the elevated expression of HSP47 in fibroblasts correlated with increased protein and mRNA levels of type I collagen. The exposure of fibroblasts to IRE1α RNase inhibitors resulted in the reduced manifestation of HSP47-induced type I collagen secretion and expression. Notably, HSP47-overexpressing fibroblasts exhibited increased XBP1 mRNA splicing. The overexpression of HSP47 or spliced XBP1 facilitated the nuclear translocation of β-catenin and transactivated a reporter harboring TCF binding sites on the promoter. Furthermore, the overexpression of HSP47 or spliced XBP1 or the augmentation of nuclear β-catenin through Wnt3a induced the expression of type I collagen. Our findings substantiate that HSP47 enhances type I collagen expression and secretion in fibroblasts by orchestrating a mechanism that involves an increase in nuclear β-catenin through IRE1α activation and XBP1 splicing. This study therefore presents potential avenues for an anti-skin-aging strategy targeting HSP47-mediated processes. [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma (PDAC) is a refractory tumor with a poor prognosis, and its complex microenvironment is characterized by a fibrous interstitial matrix surrounding PDAC cells. Type I collagen is a major component of this interstitial matrix. Abundant type I collagen promotes its deposition and cross-linking to form a rigid and dense physical barrier, which limits drug penetration and immune cell infiltration and provides drug resistance and metabolic adaptations. In this study, to identify the physical effect of the stroma, type I collagen was used as a 3D matrix to culture Capan-1 cells and generate a 3D PDAC model. Using transcriptome analysis, a link between type I collagen-induced physical effects and the promotion of Capan-1 cell proliferation and migration was determined. Moreover, metabolomic analysis revealed that the physical effect caused a shift in metabolism toward a glycolytic phenotype. In particular, the high expression of proline in the metabolites suggests the ability to maintain Capan-1 cell proliferation under hypoxic and nutrient-depleted conditions. In conclusion, we identified type I collagen-induced physical effects in promoting Capan-1 cells, which cause PDAC progression, providing support for the role of dense stroma in the PDAC microenvironment and identifying a fundamental method for modeling the complex PDAC microenvironment. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive evaluation of novel composite biomaterials designed for dental applications, aiming to potentially address the prevalent challenge of dental and periodontal tissue loss. The composites consisted of biomimetic hydroxyapatite (mHA) enriched with Mg2+, CO32−, and Zn2+ ions, type I collagen, alginate, and, additionally, chitosan and sericin. The granules were loaded with ibuprofen sodium salt. The investigation encompassed a morphology characterization, a porosity analysis, a chemical structure assessment, and an examination of the swelling behavior, drug release kinetics (ibuprofen), and release profiles of zinc and magnesium ions. The granules exhibited irregular surfaces with an enhanced homogeneity in the chitosan-coated granules and well-developed mesoporous structures. The FT-IR spectra confirmed the presence of ibuprofen sodium, despite overlapping bands for the polymers. The granules demonstrated a high water-absorption capacity, with delayed swelling observed in the chitosan-coated granules. Ibuprofen displayed burst-release profiles, especially in the G1 and G3 samples. In the case of the chitosan-coated granules (G2 and G4), lower amounts of ibuprofen were released. In turn, there was a significant difference in the released amount of magnesium and zinc ions from the granules, which was most likely caused by their different location in the hydroxyapatite crystals. The cytotoxicity assays confirmed the non-cytotoxic behavior of the biomaterial. These findings suggest the potential applicability of these biomaterials in dental scenarios, emphasizing their multifunctional and biocompatible nature. [ABSTRACT FROM AUTHOR]

The treatment of critical-size bone defects remains a complicated clinical challenge. Recently, bone tissue engineering has emerged as a potential therapeutic approach for defect repair. This study examined the biocompatibility and repair efficacy of hydroxyapatite-mineralized bionic polylactic acid (PLA) scaffolds, which were prepared through a combination of 3D printing technology, plasma modification, collagen coating, and hydroxyapatite mineralization coating techniques. Physicochemical analysis, mechanical testing, and in vitro and animal experiments were conducted to elucidate the impact of structural design and microenvironment on osteogenesis. Results indicated that the PLA scaffold exhibited a porosity of 84.1% and a pore size of 350 μm, and its macrostructure was maintained following functionalization modification. The functionalized scaffold demonstrated favorable hydrophilicity and biocompatibility and promoted cell adhesion, proliferation, and the expression of osteogenic genes such as ALP, OPN, Col-1, OCN, and RUNX2. Moreover, the scaffold was able to effectively repair critical-size bone defects in the rabbit radius, suggesting a novel strategy for the treatment of critical-size bone defects. [ABSTRACT FROM AUTHOR]

Rationale: The adult cardiac extracellular matrix (ECM) is largely comprised of type I collagen. In addition to serving as the primary structural support component of the cardiac ECM, type I collagen also provides an organizational platform for other ECM proteins, matricellular proteins, and signaling components that impact cellular stress sensing in vivo. Objective: Here we investigated how the content and integrity of type I collagen affect cardiac structure function and response to injury. Methods and Results: We generated and characterized Col1a2−/− mice using standard gene targeting. Col1a2−/− mice were viable, although by young adulthood their hearts showed alterations in ECM mechanical properties, as well as an unanticipated activation of cardiac fibroblasts and induction of a progressive fibrotic response. This included augmented TGFβ activity, increases in fibroblast number, and progressive cardiac hypertrophy, with reduced functional performance by 9 months of age. Col1a2-loxP-targeted mice were also generated and crossed with the tamoxifen-inducible Postn-MerCreMer mice to delete the Col1a2 gene in myofibroblasts with pressure overload injury. Interestingly, while germline Col1a2−/− mice showed gradual pathologic hypertrophy and fibrosis with aging, the acute deletion of Col1a2 from activated adult myofibroblasts showed a loss of total collagen deposition with acute cardiac injury and an acute reduction in pressure overload-induce cardiac hypertrophy. However, this reduction in hypertrophy due to myofibroblast-specific Col1a2 deletion was lost after 2 and 6 weeks of pressure overload, as fibrotic deposition accumulated. Conclusions: Defective type I collagen in the heart alters the structural integrity of the ECM and leads to cardiomyopathy in adulthood, with fibroblast expansion, activation, and alternate fibrotic ECM deposition. However, acute inhibition of type I collagen production can have an anti-fibrotic and anti-hypertrophic effect. [ABSTRACT FROM AUTHOR]

The matricellular secreted protein acidic and rich in cysteine (SPARC; also known as osteonectin), is involved in the regulation of extracellular matrix (ECM) synthesis, cell-ECM interactions, and bone mineralization. We found decreased SPARC expression in aged skin. Incubating foreskin fibroblasts with recombinant human SPARC led to increased type I collagen production and decreased matrix metalloproteinase-1 (MMP-1) secretion at the protein and mRNA levels. In a three-dimensional culture of foreskin fibroblasts mimicking the dermis, SPARC significantly increased the synthesis of type I collagen and decreased its degradation. In addition, SPARC also induced receptor-regulated SMAD (R-SMAD) phosphorylation. An inhibitor of transforming growth factor-beta (TGF-β) receptor type 1 reversed the SPARC-induced increase in type I collagen and decrease in MMP-1, and decreased SPARC-induced R-SMAD phosphorylation. Transcriptome analysis revealed that SPARC modulated expression of genes involved in ECM synthesis and regulation in fibroblasts. RT-qPCR confirmed that a subset of differentially expressed genes is induced by SPARC. These results indicated that SPARC enhanced ECM integrity by activating the TGF-β signaling pathway in fibroblasts. We inferred that the decline in SPARC expression in aged skin contributes to process of skin aging by negatively affecting ECM integrity in fibroblasts. [ABSTRACT FROM AUTHOR]

Type I collagen physiological scaffold for tissue regeneration is considered one of the widely used biomaterials for tissue engineering and medical applications. It is hierarchically organized: five laterally staggered molecules are packed within fibrils, arranged into fascicles and bundles. The structural organization is correlated to the direction and intensity of the forces which can be loaded onto the tissue. For a tissue-specific regeneration, the required macro- and microstructure of a suitable biomaterial has been largely investigated. Conversely, the function of multiscale structural integrity has been much less explored but is crucial for scaffold design and application. In this work, collagen was extracted from different animal sources with protocols that alter its structure. Collagen of tendon shreds excised from cattle, horse, sheep and pig was structurally investigated by wide- and small-angle X-ray scattering techniques, at both molecular and supramolecular scales, and thermo-mechanically with thermal and load-bearing tests. Tendons were selected because of their resistance to chemical degradation and mechanical stresses. The multiscale structural integrity of tendons' collagen was studied in relation to the animal source, anatomic location and source for collagen extraction. [ABSTRACT FROM AUTHOR]

We investigated how the extracellular matrix (ECM) affects LoVo colorectal cancer cells behavior during a spatiotemporal invasion. Epithelial-to-mesenchymal transition (EMT) markers, matrix-degrading enzymes, and morphological phenotypes expressed by LoVo-S (doxorubicin-sensitive) and higher aggressive LoVo-R (doxorubicin-resistant) were evaluated in cells cultured for 3 and 24 h on Millipore filters covered by Matrigel, mimicking the basement membrane, or type I Collagen reproducing a desmoplastic lamina propria. EMT and invasiveness were investigated with RT-qPCR, Western blot, and scanning electron microscopy. As time went by, most gene expressions decreased, but in type I Collagen samples, a strong reduction and high increase in MMP-2 expression in LoVo-S and -R cells occurred, respectively. These data were confirmed by the development of an epithelial morphological phenotype in LoVo-S and invading phenotypes with invadopodia in LoVo-R cells as well as by protein-level analysis. We suggest that the duration of culturing and type of substrate influence the morphological phenotype and aggressiveness of both these cell types differently. In particular, the type I collagen meshwork, consisting of large fibrils confining inter fibrillar micropores, affects the two cell types differently. It attenuates drug-sensitive LoVo-S cell aggressiveness but improves a proteolytic invasion in drug-resistant LoVo-R cells as time goes by. Experimental studies on CRC cells should examine the peri-tumoral ECM components, as well as the dynamic physical conditions of TME, which affect the behavior and aggressiveness of both drug-sensitive and drug-resistant LoVo cells differently. [ABSTRACT FROM AUTHOR]

Type I collagen and chitosan are two of the main biological macromolecules used to design scaffolds for tissue engineering. The former has the benefits of being biocompatible and provides biochemical cues for cell adhesion, proliferation and differentiation. However, collagen hydrogels usually exhibit poor mechanical properties and are difficult to functionalize. Chitosan is also often biocompatible, but is much more versatile in terms of structure and chemistry. Although it does have important biological properties, it is not a good substrate for mammalian cells. Combining of these two biomacromolecules is therefore a strategy of choice for the preparation of interesting biomaterials. The aim of this review is to describe the different protocols available to prepare Type I collagen–chitosan hydrogels for the purpose of presenting their physical and chemical properties and highlighting the benefits of mixed hydrogels over single-macromolecule ones. A critical discussion of the literature is provided to point out the poor understanding of chitosan–type I collagen interactions, in particular due to the lack of systematic studies addressing the effect of chitosan characteristics. [ABSTRACT FROM AUTHOR]

Simple Summary: The deposition of excessive collagen resulting in scarring is a detrimental outcome of the wound healing process in humans, ultimately impeding the successful restoration of skin function. Surprisingly, in Fraser's dolphins (Lagenodelphis hosei), collagens undergo a configuration change during wound healing and eventually recover to normal architecture. However, little research has been conducted on dolphins' collagen composition in the skin and the underlying mechanism during the wound healing process. Here, histochemical staining and immunostaining were performed on normal and wounded skin samples in different healing stages of Fraser's dolphins. The results demonstrate that collagens changed in composition during the wound-healing process. The mature healed wound implies the great ability to remove excessive collagen depositions in hypertrophic-like scars in Fraser's dolphins. A better understanding of collagen dynamics in Fraser's dolphins would provide more information and possibilities for solving aberrant scarring problems in humans. Fraser's dolphins (Lagenodelphis hosei) possess great healing abilities. Their skin composition can be restored after wounding, including collagen spacing, orientation, and bundle thickness. However, it remains unclear how collagens are involved in the wound-healing process and eventually regain normality in Fraser's dolphins. Learned from the other two scarless healing animals, changes in type III/I collagen composition are believed to modulate the wound healing process and influence the scarring or scarless fate determination in human fetal skin and spiny mouse skin. In the current study, Herovici's, trichrome, and immunofluorescence staining were used on normal and wounded skin samples in Fraser's dolphins. The results suggested that type I collagens were the main type of collagens in the normal skin of Fraser's dolphins, while type III collagens were barely seen. During the wound healing process, type III collagens showed at early wound healing stages, and type I collagen increased in the mature healed wound. In an early healed wound, collagens were organized in a parallel manner, showing a transient hypertrophic-like scar, and eventually restored to normal collagen configuration and adipocyte distribution in the mature healed wound. The remarkable ability to remove excessive collagens merits further investigation to provide new insights into clinical wound management. [ABSTRACT FROM AUTHOR]

Outbreaks of starfish (Asterias amurensis) pose a major threat to aquaculture and marine ecosystems in Qingdao, China, and no effective methods have been found to control them. A comprehensive study of collagen in starfish could be an alternative to high efficient utilization. Based on this, collagen was firstly extracted from Qingdao A. amurensis. Then, its protein pattern, amino acid composition, secondary structure, microstructure and thermal stability were investigated. The results showed that the A. amurensis collagen (AAC) is a type I collagen composed of α1, α2, and β chains. Glycine, hydroxyproline, and alanine were the major amino acids. The melting temperature was 57.7 °C. From FTIR, UV spectra and CD chromatography, the AAC had an intact triple helix and secondary structure, and microstructural analysis showed that the AAC had a loose, fibrous porous structure. Next, the osteogenic differentiation effect of AAC on Mouse bone marrow stem cells (BMSCs) was investigated, and the results showed that AAC induced osteogenic differentiation of cells by promoting the proliferation of BMSCs, enhancing alkaline phosphatase (ALP) activity, promoting cell mineralization nodules and upregulating the expression of mRNA of relevant osteogenic genes. These results suggest that AAC might have the potential application to bone health-related functional foods. [ABSTRACT FROM AUTHOR]

Bio-based polymers are attracting great interest due to their potential for several applications in place of conventional polymers. In the field of electrochemical devices, the electrolyte is a fundamental element that determines their performance, and polymers represent good candidates for developing solid-state and gel-based electrolytes toward the development of full-solid-state devices. In this context, the fabrication and characterization of uncrosslinked and physically cross-linked collagen membranes are reported to test their potential as a polymeric matrix for the development of a gel electrolyte. The evaluation of the membrane's stability in water and aqueous electrolyte and the mechanical characterization demonstrated that cross-linked samples showed a good compromise in terms of water absorption capability and resistance. The optical characteristics and the ionic conductivity of the cross-linked membrane, after overnight dipping in sulfuric acid solution, demonstrated the potential of the reported membrane as an electrolyte for electrochromic devices. As proof of concept, an electrochromic device was fabricated by sandwiching the membrane (after sulfuric acid dipping) between a glass/ITO/PEDOT:PSS substrate and a glass/ITO/SnO2 substrate. The results in terms of optical modulation and kinetic performance of such a device demonstrated that the reported cross-linked collagen membrane could represent a valid candidate as a water-based gel and bio-based electrolyte for full-solid-state electrochromic devices. [ABSTRACT FROM AUTHOR]

The mechanism behind how flavin mononucleotide (FMN)-producing bacteria attach to a host intestine remains unclear. In order to address this issue, this study isolated the Gram-positive bacteria Lactobacillus plantarum from Mongolian fermented Airag, named L. plantarum MA. These bacteria were further employed as the model microbes, and their electrogenic properties were first identified by their significant expression of type II NADH-quinone oxidoreductase. This study also demonstrated that the electrical activity of L. plantarum MA can be conducted through flavin mononucleotide (FMN)-based extracellular electron transfer, which is highly dependent on the presence of a carbon source in the medium. Our data show that approximately 15 µM of FMN, one of the key electron donors for the generation of electricity, can be produced from L. plantarum MA, as they were cultured in the presence of lactulose for 24 h. We further demonstrated that the electrical activity of L. plantarum MA can promote microbial adhesion and can thus enhance the colonization effectiveness of Caco-2 cells and mouse cecum. Such enhanced adhesiveness was attributed to the increased expression of type I collagens in the intestinal epithelium after treatment with L. plantarum MA. This study reveals the mechanism behind the electrogenic activity of L. plantarum MA and shows how the bacteria utilize electricity to modulate the protein expression of gut tissue for an enhanced adhesion process. [ABSTRACT FROM AUTHOR]

Type I and V collagens are the major components of fibrillogenic proteins in fish skin, and their hydrolysis products possess hyaluronidase inhibitory activity. In this study, for the first time, type I and V collagens were isolated from the skin of shortbill spearfish and striped marlin. Type I (2α1[I]α2[I]) and type V (α1[V]α3[V]α2[V]) collagens composed of distinct α-peptide chains with comparable structures were investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and UV spectrophotometric chromatography. After enzymatic digestion, the collagen peptides were purified by using ultrafiltration (30 KDa) and high-performance liquid chromatography (RP-HPLC) to yield CPI-F3 and CPV-F4 fractions with strong hyaluronidase inhibition rates (42.17% and 30.09%, respectively). Based on the results of simulated gastrointestinal fluid, temperature, and pH stability assays, CPI-F3 and CPV-F4 exhibited stability in gastric fluid and showed no significant changes under the temperature range from 50 to 70 °C (p > 0.05). The results of this first research on the bioactivity of type V collagen peptides provide valuable information for the biomedical industry and show the potential for future bioactivity investigations of type V collagen and its peptides. [ABSTRACT FROM AUTHOR]

The epithelial–mesenchymal transition (EMT) is an important biological process that is physiologically observed during development, wound healing, and cancer invasion. During EMT induction, cancer cells lose their epithelial properties owing to various tumor microenvironmental factors and begin to exhibit mesenchymal properties, such as loss of apical–basal polarity, weakened intercellular adhesion, and promotion of single cell migration. Several factors, including growth factor stimulation and adhesion to type I collagen (Col-I), induce EMT in cancer cells. Cells adhere to Col-I via specific receptors and induce EMT by activating outside-in signals. In vivo, Col-I molecules often form fibrils, which then assemble into supramolecular structures (gel form). Col-I also self-assembles in vitro under physiological conditions. Notably, Col-I can be used as a culture substrate in both gel and non-gel forms, and the gel formation state of Col-I affects cell fate. Although EMT can be induced in both forms of Col-I, the effects of gel formation on EMT induction remain unclear and somewhat inconsistent. Therefore, this study reviews the relationship between Col-I gel-forming states and EMT induction in cancer cells. [ABSTRACT FROM AUTHOR]

Aim of the study was to understand the behavior of colon cancer LoVo-R cells (doxorubicin-resistant) vs. LoVo-S (doxorubicin sensitive) in the initial steps of extracellular matrix (ECM) invasion. We investigated how the matrix substrates Matrigel and type I collagen-mimicking the basement membrane (BM) and the normal or desmoplastic lamina propria, respectively-could affect the expression of epithelial-to-mesenchymal transition (EMT) markers, matrix-degrading enzymes, and phenotypes. Gene expression with RT-qPCR, E-cadherin protein expression using Western blot, and phenotypes using scanning electron microscopy (SEM) were analyzed. The type and different concentrations of matrix substrates differently affected colon cancer cells. In LoVo-S cells, the higher concentrated collagen, mimicking the desmoplastic lamina propria, strongly induced EMT, as also confirmed by the expression of Snail, metalloproteases (MMPs)-2, -9, -14 and heparanase (HPSE), as well as mesenchymal phenotypes. Stimulation in E-cadherin expression in LoVo-S groups suggests that these cells develop a hybrid EMT phenotype. Differently, LoVo-R cells did not increase their aggressiveness: no changes in EMT markers, matrix effectors, and phenotypes were evident. The low influence of ECM components in LoVo-R cells might be related to their intrinsic aggressiveness related to chemoresistance. These results improve understanding of the critical role of tumor microenvironment in colon cancer cell invasion, driving the development of new therapeutic approaches. [ABSTRACT FROM AUTHOR]

Aminocarbonyl proteins increase with age in the dermal layer. Gene Chip analysis of mRNA expression in human dermal fibroblasts cultured on collagen gels treated with glyceraldehyde as an aminocarbonyl protein and on untreated collagen gels showed a decrease in the amount of aquaporin 1 (AQP1) mRNA. In this study, we clarified the involvement of AQP1 in collagen gel contraction and the production of fibrillin 1 and type I collagen in cultured human dermal fibroblasts. In the experiment, AQP1 siRNA was transfected into cultured human dermal fibroblasts to deplete AQP1, and the cell motility and contractile activity of the collagen gel were assessed. The production of fibrillin 1 and type I collagen was also examined by RT–qPCR and antibody staining. AQP1 depletion decreased the collagen gel contractile activity, and both the amount of mRNA and the antibody staining of fibrillin 1 and type I collagen decreased. Furthermore, the depletion of AQP1 reduced the levels of F-actin and phosphorylated myosin light chain 2, suggesting their involvement in reductions of the motility and collagen gel contractile activity of fibroblasts. These findings suggest that AQP1 is an important biomolecule for cell motility in human dermal fibroblasts and that decreased motility results in decreased expression of extracellular matrix proteins such as fibrillin 1 and type I collagen. [ABSTRACT FROM AUTHOR]

Simple Summary: One cause of parturition abnormalities in cows may be the insufficient opening of the birth canal; however, the process by which the canal becomes flexible in cows is unknown. Herein, we observed changes in the cervix from late pregnancy to parturition to clarify the physiological changes related to cervical ripening during normal calving. Mucus and tissue samples from the cervix were collected from 41 cows at 30-day intervals from 200 to 260 days of gestation and at 7-day intervals from 260 days of gestation to parturition. The percentage of neutrophils in the mucus (PMN%) was calculated, and the concentration of interleukin (IL)-8, an inflammatory cytokine, was measured. The cervical tissues were observed under a microscope, and the percentage of type I collagen was calculated. The PMN% in the cervical mucus increased 5 weeks before delivery, peaking 1 week before calving; IL-8 was significantly increased at 295 days compared to that at 200 days of gestation. The percentage of type I collagen in the cervical tissue decreased significantly from 200 days to 274 days of pregnancy and continued to decrease thereafter until the week of calving. In conclusion, the cervix of cows begins to ripen at approximately 260 days of pregnancy. Dystocia and stillbirths in cows pose a high risk of loss of both dams and fetuses, thereby resulting in high economic losses. One of the causes of these problems is birth canal abnormalities. Thus, to prevent these occurrences, it is necessary to understand the mechanisms underlying cervical ripening. Although physiological inflammatory responses and changes in collagen composition have been reported in humans and mice, related information is scarce for cows. We observed inflammatory changes and changes in the collagen composition in the cervix from late pregnancy to parturition to clarify some of the physiological changes associated with cervical ripening during normal calving in cows. Cervical mucus and tissue samples were collected from 41 Japanese Black cows at 200, 230, and 260 days of gestation and at 7-day intervals thereafter until parturition. The percentage of polymorphonuclear neutrophils (PMN%) in the mucus was calculated, and interleukin (IL)-8 concentration was determined by enzyme-linked immunosorbent assay. Blood samples were collected from the jugular vein, and leukocyte counts were determined. Picrosirius red-stained cervical tissue specimens were observed under a polarizing microscope, and the percentage of type I and type III collagen areas in the cervical tissue were calculated. The PMN% in cervical mucus was lowest at 200 days gestation (12–13 weeks before delivery), significantly increased 5 weeks before (21.7 ± 0.04), and was highest 1 week before calving (50.9 ± 0.04). IL-8 levels were increased at 295 days compared with those at 200 days of pregnancy (p < 0.05). No significant changes were observed in the white blood cell counts. The percentage of type I collagen in the cervical tissue reached a maximum (91.4 ± 0.02%) on day 200, significantly decreased after 274 days (3 weeks before calving), and continued to decrease thereafter until the week of parturition. There was no significant change in type III collagen levels. The results suggest that cervical ripening progresses when PMNs begin to infiltrate the cervix at around 260 days of gestation (5–4 weeks before parturition), IL-8, which increases at the end of pregnancy, mobilizes PMNs, and enhances inflammation, and that type I collagen changes are useful as an indicator of cervical ripening. [ABSTRACT FROM AUTHOR]

Oxidative stress is the leading cause of skin aging damage. Excessive accumulation of reactive oxygen species (ROS) in cells induced by hydrogen peroxide (H2O2) triggers a decrease in collagen synthesis and an increase in collagen degradation, which are biomarkers of skin aging. We evaluated the potential protective mechanism of Sea buckthorn proanthocyanidins (SBP) against the oxidative stress-induced skin aging process from multiple aspects. We treated human skin fibroblasts (HSFs) with 300 µmoL/L of H2O2 for 24 h, followed by 25, 50, and 100 µg/mL of SBP for 24 h. The results showed that SBP could enhance the activities of superoxide dismutase (SOD) and glutathione (GSH), effectively remove excess ROS, and significantly improve the changes in cell morphology and viability caused by excessive ROS in skin cells. In addition, SBP could promote the synthesis of Col I in aging HSFs through the TGF-β1/Smads pathway and inhibit the degradation of Col I by regulating the MMPs/TIMPs system, thereby maintaining the stability of the ECM structure to achieve anti-aging purposes. Finally, we studied the migration ability of SBP, and the results showed that 100 µg/mL of SBP was most conducive to the cell migration of senescent cells, laying a foundation for follow-up animal experiments. These results will increase the application value of SBP in the cosmetic and antioxidative functional food industries. [ABSTRACT FROM AUTHOR]

The treatment of osteoporotic fractures is a severe clinical issue, especially in cases where low support is provided, e.g., pelvis. New treatments aim to stimulate bone formation in compromised scenarios by using multifunctional biomaterials combined with biofabrication techniques to produce 3D structures (scaffolds) that can support bone formation. Bone's extracellular matrix (ECM) is mainly composed of type I collagen, making this material highly desirable in bone tissue engineering applications, and its bioactivity can be improved by incorporating specific biomolecules. In this work, type I collagen membranes were produced by electrospinning showing a fibre diameter below 200 nm. An optimized one-step strategy allowed to simultaneously crosslink the electrospun membranes and bind ICOS-Fc, a biomolecule able to reversibly inhibit osteoclast activity. The post-treatment did not alter the ECM-like nanostructure of the meshes and the physicochemical properties of collagen. UV-Vis and TGA analyses confirmed both crosslinking and grafting of ICOS-Fc onto the collagen fibres. The preservation of the biological activity of grafted ICOS-Fc was evidenced by the ability to affect the migratory activity of ICOSL-positive cells. The combination of ICOS-Fc with electrospun collagen represents a promising strategy to design multifunctional devices able to boost bone regeneration in osteoporotic fractures. [ABSTRACT FROM AUTHOR]

Zirconia, with its excellent mechanical strength and esthetics, has a growing potential for applications in dentistry and orthopedics. However, in order for zirconia to have a high affinity with bone tissue, the bioactivity of the surface must be further increased. In order to increase the bioactivity of zirconia, research was conducted to make a porous support or to fill the porous structure with nano-hydroxyapatite (nHA). In this case, there is a risk that physically filled nHA could be released depending on the living environment. In this study, nHA and type I collagen were introduced to the zirconia surface by chemical covalent bonding to increase bioactivity and ensure safety in the body. The chemical reaction of the surface was confirmed by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. In addition, the biological activity was evaluated by examining the cytotoxicity and bone formation ability of the modified zirconia using osteoblasts. As a result, it was found that the bioactivity of the zirconia surface was greatly improved by immobilizing nHA and type I collagen. [ABSTRACT FROM AUTHOR]

Systemic sclerosis (SSc) is characterized by excessive collagen deposition in the skin and internal organs. Activated fibroblasts are the key effector cells for the overproduction of type I collagen, which comprises the α1(I) and α2(I) chains encoded by COL1A1 and COL1A2, respectively. In this study, we examined the expression patterns of α1(I) and α2(I) collagen in SSc fibroblasts, as well as their co-regulation with each other. The relative expression ratio of COL1A1 to COL1A2 in SSc fibroblasts was significantly higher than that in control fibroblasts. The same result was observed for type I collagen protein levels, indicating that α2(I) collagen is more elevated than α2(I) collagen. Inhibition or overexpression of α1(I) collagen in control fibroblasts affected the α2(I) collagen levels, suggesting that α1(I) collagen might act as an upstream regulator of α2(I) collagen. The local injection of COL1A1 small interfering RNA in a bleomycin-induced SSc mouse model was found to attenuate skin fibrosis. Overall, our data indicate that α2(I) collagen is a potent regulator of type I collagen in SSc; further investigations of the overall regulatory mechanisms of type I collagen may help understand the aberrant collagen metabolism in SSc. [ABSTRACT FROM AUTHOR]

Collagen from fish has been proven to have a low antigenicity that has no difference in the genetic codes compared with mammalian-based collagen. This study was designed to investigate the impact of tilapia skin collagen on immunogenicity and biocompatibility in vivo and in vitro. The structural characteristics of both acid-soluble and pepsin-soluble collagen (ASC and PSC), determined using SDS-PAGE and atomic force microscopy imaging experiments, revealed that the collagen had the basic characteristics of type I collagen (COL-I). The in vitro biocompatibility of the collagens showed good cell proliferation against human foreskin fibroblast (HFF-1) cells. PSC and ASC were considered to be almost non-hemolytic biomaterials with favorable blood compatibility in hemolysis tests. The in vivo antigenicity of the collagen in an ICR mouse model evoked an acceptable specific inflammatory response compared to bovine collagen. The implant's position had developed a complete granulation tissue and the sponge disappeared after 8 weeks. The level of cytokines produced by the COL-I immune response was much lower than bovine collagen, which indicated the appropriate implantable property and biodegradability of the collagens. In conclusion, the tilapia COL-I has a lower immunogenicity with better compatibility than bovine COL-I and is a potential alternative to conventional mammalian collagens in biomedical uses. [ABSTRACT FROM AUTHOR]

Collagen is one of the most widely used biomaterials in health-related sectors. The industrial production of collagen mostly relies on its extraction from mammals, but several issues limited its use. In the last two decades, marine organisms attracted interest as safe, abundant, and alternative source for collagen extraction. In particular, the possibility to valorize the huge quantity of fish industry waste and byproducts as collagen source reinforced perception of fish collagen as eco-friendlier and particularly attractive in terms of profitability and cost-effectiveness. Especially fish byproducts from eco-sustainable aquaponics production allow for fish biomass with additional added value and controlled properties over time. Among fish species, Oreochromis niloticus is one of the most widely bred fish in large-scale aquaculture and aquaponics systems. In this work, type I collagen was extracted from aquaponics-raised Tilapia skin and characterized from a chemical, physical, mechanical, and biological point of view in comparison with a commercially available analog. Performed analysis confirmed that the proprietary process optimized for type I collagen extraction allowed to isolate pure native collagen and to preserve its native conformational structure. Preliminary cellular studies performed with mouse fibroblasts indicated its optimal biocompatibility. All data confirmed the eligibility of the extracted Tilapia-derived native type I collagen as a biomaterial for healthcare applications. [ABSTRACT FROM AUTHOR]

Type I collagen is the main component of the extracellular matrix that acts as the physical and biochemical support of tissues. Thanks to its characteristics, collagen is widely employed as a biomaterial for implantable device fabrication and as antiaging food supplementation. Because of the BSE transmission in the 1990s, aquatic animals have become a more suitable extraction source than warm-blooded animals. Moreover, as recently demonstrated, a supplementing diet with fish collagen can increase the body's collagen biosynthesis. In this context, Tilapia feeding was supplemented with hydrolyzed collagen in order to enhance the yield of extracted collagen. Tilapia skin was investigated with wide and small angle scattering techniques, analyzing the collagen structure from the submolecular to the nanoscale and correlated with Differential Scanning Calorimetry (DSC) measurements. Our studies demonstrated that the supplementation appears to have an effect at the nanoscale in which fibrils appear more randomly oriented than in fish fed with no supplemented feed. Conversely, no effect of a collagen-rich diet was observed at the submolecular scale. [ABSTRACT FROM AUTHOR]

Type I collagen, the predominant protein of vertebrates, assembles into fibrils that orchestrate the form and function of bone, tendon, skin, and other tissues. Collagen plays roles in hemostasis, wound healing, angiogenesis, and biomineralization, and its dysfunction contributes to fibrosis, atherosclerosis, cancer metastasis, and brittle bone disease. To elucidate the type I collagen structure-function relationship, we constructed a type I collagen fibril interactome, including its functional sites and disease-associated mutations. When projected onto an X-ray diffraction model of the native collagen microfibril, data revealed a matrix interaction domain that assumes structural roles including collagen assembly, crosslinking, proteoglycan (PG) binding, and mineralization, and the cell interaction domain supporting dynamic aspects of collagen biology such as hemostasis, tissue remodeling, and cell adhesion. Our type III collagen interactome corroborates this model. We propose that in quiescent tissues, the fibril projects a structural face; however, tissue injury releases blood into the collagenous stroma, triggering exposure of the fibrils' cell and ligand binding sites crucial for tissue remodeling and regeneration. Applications of our research include discovery of anti-fibrotic antibodies and elucidating their interactions with collagen, and using insights from our angiogenesis studies and collagen structure-function model to inform the design of super-angiogenic collagens and collagen mimetics. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) reside quiescently within a specialised 'niche' environment in the bone marrow. However, following appropriate signalling cues, MSCs mobilise and migrate out from the niche, typically toward either sites of injury (a regenerative response) or toward primary tumours (an intrinsic homing response, which promotes MSCs as cellular vectors for therapeutic delivery). To date, very little is known about MSC mobilisation. By adopting a 3D MSC niche model, whereby MSC spheroids are cultured within a type I collagen gel, recent studies have highlighted interleukin-6 (IL-6) as a key cytokine involved in MSC migration. Herein, the ability of IL-6 to induce MSC migration was further investigated, and the key matrix metalloproteinases used to effect cell mobilisation were identified. Briefly, the impact of IL-6 on the MSC migration in a two-dimensional model systems was characterised--both visually using an Ibidi chemotaxis plate array (assessing for directional migration) and then via a standard 2D monolayer experiment, where cultured cells were challenged with IL-6 and extracted media tested using an Abcam Human MMP membrane antibody array. The 2D assay displayed a strong migratory response toward IL-6 and analysis of the membrane arrays data showed significant increases of several key MMPs. Both data sets indicated that IL-6 is important in MSC mobilisation and migration. We also investigated the impact of IL-6 induction on MSCs in 3D spheroid culture, serving as a simplistic model of the bone marrow niche, characterised by fluorescently tagged magnetic nanoparticles and identical membrane antibody arrays. An increase in MMP levels secreted by cells treated with 1 ng/mL IL-6 versus control conditions was noted in addition to migration of cells away from the central spheroid mass. [ABSTRACT FROM AUTHOR]

In this study, type I collagen was coated onto unmodified and modified microporous biphasic calcium phosphate (BCP) scaffolds. Surface characterization using a scanning electron microscope (SEM) and a surface goniometer confirmed the modification of the BCP coating. The quantity of the collagen coating was investigated using Sirius Red staining, and quantitative assessment of the collagen coating showed no significant differences between the two groups. MG63 cells were used to evaluate cell proliferation and ALP activity on the modified BCP scaffolds. The modified microporous surfaces showed low contact angles and large surface areas, which enhanced cell spreading and proliferation. Coating of the BCP scaffolds with type I collagen led to enhanced cell-material interactions and improved MG63 functions, such as spreading, proliferation, and differentiation. The micropore/collagen-coated scaffold showed the highest rate of cell response. These results indicate that a combination of micropores and collagen enhances cellular function on bioengineered bone allograft tissue. [ABSTRACT FROM AUTHOR]

The epithelial-mesenchymal transition (EMT) is an important biological process that is physiologically observed during development, wound healing, and cancer invasion. During EMT induction, cancer cells lose their epithelial properties owing to various tumor microenvironmental factors and begin to exhibit mesenchymal properties, such as loss of apical-basal polarity, weakened intercellular adhesion, and promotion of single cell migration. Several factors, including growth factor stimulation and adhesion to type I collagen (Col-I), induce EMT in cancer cells. Cells adhere to Col-I via specific receptors and induce EMT by activating outside-in signals. In vivo, Col-I molecules often form fibrils, which then assemble into supramolecular structures (gel form). Col-I also self-assembles in vitro under physiological conditions. Notably, Col-I can be used as a culture substrate in both gel and non-gel forms, and the gel formation state of Col-I affects cell fate. Although EMT can be induced in both forms of Col-I, the effects of gel formation on EMT induction remain unclear and somewhat inconsistent. Therefore, this study reviews the relationship between Col-I gel-forming states and EMT induction in cancer cells.

Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long SWCNTs was assessed via oxidative stress generation, collagen expression and transforming growth factor-beta (TGF-ß) production as potential fibrosis biomarkers. Long SWCNTs were significantly more potent than short SWCNTs in terms of reactive oxygen species (ROS) response, collagen production and TGF-ß release. Furthermore, our finding on the length-dependent in vitro fibrogenic response was validated by the in vivo lung fibrosis outcome, thus supporting the predictive value of the in vitro model. Our results also demonstrated the key role of ROS in SWCNT-induced collagen expression and TGF-ß activation, indicating the potential mechanisms of length-dependent SWCNT-induced fibrosis. Together, our study provides new evidence for the role of fiber length in SWCNT-induced lung fibrosis and offers a rapid cell-based assay for fibrogenicity testing of nanomaterials with the ability to predict pulmonary fibrogenic response in vivo. [ABSTRACT FROM AUTHOR]

In bone regenerative strategies, the controlled release of growth factors is one of the main aspects for successful tissue regeneration. Recent trends in the drug delivery field increased the interest in the development of biodegradable systems able to protect and transport active agents. In the present study, we designed degradable poly(lactic-co-glycolic)acid (PLGA) nanocarriers suitable for the release of Transforming Growth Factor-beta 1 (TGF-β1), a key molecule in the management of bone cells behaviour. Spherical TGF-β1-containing PLGA (PLGA_TGF-β1) nanoparticles (ca.250 nm) exhibiting high encapsulation efficiency (ca.64%) were successfully synthesized. The TGF-β1 nanocarriers were subsequently combined with type I collagen for the fabrication of nanostructured 3D printed scaffolds able to mimic the TGF-β1 presence in the human bone extracellular matrix (ECM). The homogeneous hybrid formulation underwent a comprehensive rheological characterisation in view of 3D printing. The 3D printed collagen-based scaffolds (10 mm × 10 mm × 1 mm) successfully mimicked the TGF-β1 presence in human bone ECM as assessed by immunohistochemical TGF-β1 staining, covering ca.3.4% of the whole scaffold area. Moreover, the collagenous matrix was able to reduce the initial burst release observed in the first 24 h from about 38% for the PLGA_TGF-β1 alone to 14.5%, proving that the nanocarriers incorporation into collagen allows achieving sustained release kinetics. [ABSTRACT FROM AUTHOR]

Nonalcoholic steatohepatitis (NASH) is a disease closely associated with obesity and diabetes. A prevalence of type 2 diabetes and a high body mass index in cryptogenic cirrhosis may imply that obesity leads to cirrhosis. Here, we examined the effects of an extract of Ecklonia cava, a brown algae, on the activation of high glucose-induced hepatic stellate cells (HSCs), key players in hepatic fibrosis. Isolated HSCs were incubated with or without a high glucose concentration. Ecklonia cava extract (ECE) was added to the culture simultaneously with the high glucose. Treatment with high glucose stimulated expression of type I collagen and α-smooth muscle actin, which are markers of activation in HSCs, in a dose-dependent manner. The activation of high glucose-treated HSCs was suppressed by the ECE. An increase in the formation of intracellular reactive oxygen species (ROS) and a decrease in intracellular glutathione levels were observed soon after treatment with high glucose, and these changes were suppressed by the simultaneous addition of ECE. High glucose levels stimulated the secretion of bioactive transforming growth factor-β (TGF-β) from the cells, and the stimulation was also suppressed by treating the HSCs with ECE. These results suggest that the suppression of high glucose-induced HSC activation by ECE is mediated through the inhibition of ROS and/or GSH and the downregulation of TGF-β mediated through the inhibition of ROS and/or GSH and the downregulation of TGF-β secretion. ECE is useful for preventing the development of diabetic liver fibrosis. secretion. ECE is useful for preventing the development of diabetic liver fibrosis. [ABSTRACT FROM AUTHOR]

Bone strength and the incidence and severity of skeletal disorders vary significantly among human populations, due in part to underlying genetic differentiation. While clinical models predict that this variation is largely deleterious, natural population variation unrelated to disease can go unnoticed, altering our perception of how natural selection has shaped bone morphologies over deep and recent time periods. Here, we conduct the first comparative population-based genetic analysis of the main bone structural protein gene, collagen type I α 1 (COL1A1), in clinical and 1000 Genomes Project datasets in humans, and in natural populations of chimpanzees. Contrary to predictions from clinical studies, we reveal abundant COL1A1 amino acid variation, predicted to have little association with disease in the natural population. We also find signatures of positive selection associated with intron haplotype structure, linkage disequilibrium, and population differentiation in regions of known gene expression regulation in humans and chimpanzees. These results recall how recent and deep evolutionary regimes can be linked, in that bone morphology differences that developed among vertebrates over 450 million years of evolution are the result of positive selection on subtle type I collagen functional variation segregating within populations over time. [ABSTRACT FROM AUTHOR]

Osteoporosis is a worldwide disease resulting in the increase of bone fragility and enhanced fracture risk in adults. In the context of osteoporotic fractures, bone tissue engineering (BTE), i.e., the use of bone substitutes combining biomaterials, cells, and other factors, is considered a potential alternative to conventional treatments. Innovative scaffolds need to be tested in in vitro systems where the simultaneous presence of osteoblasts (OBs) and osteoclasts (OCs), the two main players of bone remodeling, is required to mimic their crosstalk and molecular cooperation. To this aim, two composite materials were developed, based on type I collagen, and containing either strontium-enriched mesoporous bioactive glasses or rod-like hydroxyapatite nanoparticles. The developed nanostructured systems underwent genipin chemical crosslinking and were then tested with an indirect co-culture of human trabecular bone-derived OBs and buffy coat-derived OC precursors, for 2–3 weeks. The favorable structural and biological properties of the materials proved to successfully support the viability, adhesion, and differentiation of cells, encouraging a further investigation of the developed bioactive systems as biomaterial inks for the 3D printing of more complex scaffolds for BTE. [ABSTRACT FROM AUTHOR]

Urethral stenosis is a pathological condition that consists in the narrowing of the urethral lumen because of the formation of scar tissue. Unfortunately, none of the current surgical approaches represent an optimal solution because of the high stricture recurrence rate. In this context, we preliminarily explored the potential of an insoluble type-I collagen from horse tendon as scaffolding material for the development of innovative devices for the regeneration of injured urethral tracts. Non-porous collagen-based substrates were produced and optimized, in terms of crosslinking density of the macromolecular structure, to either provide mechanical properties compliant with the urinary tract physiological stress and better sustain tissue regeneration. The effect of the adopted crosslinking strategy on the protein integrity and on the substrate physical–chemical, mechanical and biological properties was investigated in comparison with a decellularized matrix from porcine small intestinal submucosa (SIS patch), an extensively used xenograft licensed for clinical use in urology. The optimized production protocols allowed the preservation of the type I collagen native structure and the realization of a substrate with appealing end-use properties. The biological response, preliminarily investigated by immunofluorescence experiments on human adult renal stem/progenitor cells until 28 days, showed the formation of a stem-cell monolayer within 14 days and the onset of spheroids within 28 days. These results suggested the great potential of the collagen-based material for the development of scaffolds for urethral plate regeneration and for in vitro cellular studies. [ABSTRACT FROM AUTHOR]