The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development

Microfluidic cell carriers for cultured meat

Cultured meat aims to produce meat mass from cell culture instead of conventional livestock slaughtering. Due to anchorage-dependent and 3D culturing manner of cells, cell carriers are critical in cultured meat. Various cell carriers have been used for expansion of seed cells and cultured meat tissue construction, such as commercial microcarriers, electrospray microspheres, and 3D-printed microfibers, but facing suboptimal effect of cell growth and specific differentiation. Compared to traditional methods, microfluidics can purposefully fabricate cell carriers with diverse structures and components, thereby achieving adequate simulation of natural muscle. Research has shown that microfluidic fibrous carriers possessed excellent effect in cultured meat tissue construction. This review overviews application and potential of microfluidic cell carriers in cultured meat. Starting with introduction of materials for carrier construction, we discuss limitations of traditional cell carriers and focus on microfluidic carrier in cultured meat. Finally, we present challenges and perspectives of microfluidics for cultured meat.

Hydroxyapatite microspheres encapsulated within hybrid hydrogel promote skin regeneration through the activation of Calcium Signaling and Motor Protein pathway

Hydroxyapatite (HAp), traditionally recognized for its efficacy in bone regeneration, has rarely been explored for skin regeneration applications. This investigation explored HAp microspheres with distinct physicochemical properties tailored away from conventional bone regeneration parameters, and the capacity promoting skin regeneration and mitigating the aging process were investigated when encapsulated in hyaluronate hydrogels. By benchmarking against well-established dermal fillers like PMMA and PLLA, it was revealed the specific attributes of HAp that were conducive to skin regeneration, providing initial insights into the underlying mechanism. HAp enhanced the fibroblast functionality by triggering minimal adaptive immune responses and enhancing the Calcium Signaling and Motor Protein Signaling pathways. This modulation supported the production of normal collagen fibers, essential for ECM maturation and skin structural integrity. The significant ECM regeneration and remodeling capabilities exhibited by the HAp-encapsulated hybrid hydrogels suggested promising application in facial rejuvenation procedures, potentially making a breakthrough in aesthetic and reconstructive surgery.

Rational designation and characterization of a novel humanized collagen capable of self-assembling into triple helix and fibrils with D-period

The triple helix and D-period are distinctive features of native collagen, crucial for its physicochemical properties and bioactivities. However, developing recombinant humanized collagen with D-period features remains elusive. Here, we present a strategy for preparing a novel recombinant humanized collagen using a 'charged-hydrophobic-charged amino acid' sequence with the capacity of self-assembling. The hydrophobic amino acids in the middle region are believed to be crucial for the triple helix formation while the charged amino acids at the C- and N-terminal drive the triple-helix to self-assemble into higher-order structures like fibrils, with D-period formation during this process. To prove this concept, the particular fragment of Gly1059-Ala1103 of human type III collagen, featuring arginine (R), lysine (K), aspartic acid (D), and glutamic acid (E)-rich termini and a Glycine-Proline-Alanine (G-P-A) central motif, was selected and repeated to construct a recombinant humanized collagen, designated as rhCL04. This construct successfully formed hierarchical structures, including triple helices, rod-like fibrils, and hydrogels, exhibiting a distinct 10 nm D-period across a broad pH range from 4 to 10. Additionally, cell adhesion and biocompatibility were confirmed using L929 mouse fibroblast cells, demonstrating the ability to promote cell adhesion activity and no significant cytotoxicity. Our study provides valuable insights into the self-assembling mechanisms of native collagens. Moreover, these results highlight the efficacy of this strategy in producing recombinant humanized collagen with collagen-like characteristics. The simplicity and versatility of the approach, combined with the excellent self-assembling properties and biological activity of rhCL04, underscore its potential for biomaterial production.

Development of a Sensory Neuron-Integrated Skin Spheroid Model for the Evaluation of Neuropeptide-Based Topical Delivery Systems

The skin is a complex organ composed of multiple layers and diverse cell types, including keratinocytes, fibroblasts, adipocytes, and sensory neurons, which maintain its structural and functional integrity together. Conventional in vitro and ex vivo models help investigate drug permeation and selected biological effects. However, they are limited in replicating neural interactions critical for assessing the efficacy of neuropeptide-based therapies. To address this limitation, a sensory neuron-integrated skin spheroid (SS) model was established, incorporating key skin cell types and providing a rapid, adaptable, and physiologically relevant platform for screening the biological activity of topical delivery systems targeting neuronal pathways. The model's responsiveness was demonstrated using acetyl hexapeptide-3 (HEX-3), a neuropeptide that inhibits acetylcholine release. HEX-3 was internalized by spheroid cells, with preferential accumulation around sensory neurons, confirming targeted cellular uptake. In parallel, ex vivo human skin studies confirmed that HEX-3 can traverse the stratum corneum and accumulate in deeper layers. Treatment with this film enhanced skin hydration, reduced scaling, and improved the structural organization of the stratum corneum after 48 h. Functional assays using the SS model showed that HEX-3 treatment suppressed acetylcholine release, upregulated the antioxidant enzyme SOD2, and stimulated type I collagen synthesis. In aged skin samples, the application of HEX-3 significantly increased collagen levels. This effect was mirrored in the spheroid model, which reached collagen levels comparable to those of aged human skin upon treatment. These findings establish the SS model as a robust platform for evaluating the biological activity of neuropeptide-based topical therapies, offering valuable insights for developing advanced strategies for skin rejuvenation and repair.

Natural polysaccharide and protein-based hydrogels: a novel class of materials for sustainable agricultural development

As global population growth and resource constraints intensify, traditional agriculture relies on high-energy consumption and high-pollution measures that can no longer support the demand for sustainable development. Owing to their biocompatibility, degradability and functional diversity, natural polysaccharide- and protein-based hydrogels have become ideal materials for supporting the sustainable use of agricultural soils. This paper systematically reviews the design and preparation of such hydrogels and their potential for agricultural applications. First, in terms of the raw material properties, the molecular structure of polysaccharides and proteins endows hydrogels with excellent water absorption and retention capacity, stimulus responsiveness and environmental adaptability; second, the mechanical strength, swelling behaviour and degradation rate of hydrogels can be precisely regulated through physical cross-linking or chemical cross-linking. At the application level, natural polysaccharide- and protein-based hydrogels subsequently exhibit multidimensional functions. They act as 'miniature reservoirs' to optimise soil water management and the slow release of fertilisers and pesticides to improve utilisation efficiency; they can repair degraded soils and inhibit salinisation by improving the structure of soil aggregates, increasing the content of organic matter, and adsorbing heavy metal ions; and their degradation products can provide carbon sources for soil microorganisms to synergistically promote crop growth. Finally, this paper summarises the research progress on using natural polysaccharide- and protein-based hydrogels in theiragriculture, proposes a vision for the development of next-generation hydrogels based on their multifunctionality, smart responsiveness and practical applications and provides efficient, adaptive and environmentally compatible solutions for sustainable agriculture.

Structural and Mechanical Characterization of Collagen-Hyaluronan Hydrogels Used to Study Cancer Cell Invasion through the Bladder Wall

Collagen-hyaluronic acid (Col-HA) hydrogels are widely studied as biomimetic materials that recapitulate the environmental physical and mechanical properties crucial for understanding the cell behavior during cancer invasion and progression. Our research focused on Col-HA hydrogels as an environment to study the invasion of bladder cancer cells through the bladder wall. The bladder is a heterogeneous structure composed of three main layers: urothelium (the softest), lamina propria (the stiffest), and the muscle outer layer, with elastic properties lying between the two. Thus, the bladder cancer cells migrate through the mechanically distinct environments. We investigated the impact of Col-HA hydrogel microstructure and rheology on migrating bladder cancer T24 cells from the cancer spheroid surface to the surrounding environment formed from various collagen I and HA concentrations and chemical structures. The designed hydrogels showed variability in network density and rheological properties. The migration of bladder cancer cells was inhibited inside hydrogels of ∼1 kPa storage modulus. The correlation analysis showed that collagen concentration primarily defined the rheological properties of Col-HA hydrogels, but hydrogels can soften or stiffen depending on the type of HA used. Within soft Col-HA hydrogels, cells freely invade the surrounding environment, while its stiffening impedes cell movement and almost inhibits cell migration. Only individual, probably leading, cells are observed at the spheroid edges initiating the invasion. Our findings showed that the rheological properties of the hydrogels dominate in regulating cancer cell migration, providing a platform to study how bladder cancer cells migrate through the heterogeneous structure of the bladder wall.

In Vivo Evaluation of the Anti-Skin-Ageing Bioactivity of a Recombinant Dual Humanised Collagen and Poly-L-Lactic Acid

This study introduces a novel recombinant humanised collagen (DuCol) developed through codon optimisation and prokaryotic soluble expression, exhibiting exceptional biocompatibility and bioactivity. Structural integrity was confirmed via RP-HPLC, SEM, and CD spectroscopy. In vitro evaluations revealed DuCol's dose-dependent enhancement of NIH-3T3 fibroblast proliferation, adhesion, and migration. In a D-galactose-induced ageing rat model, subcutaneous implantation of DuCol showcased time-dependent anti-ageing effects. Early-stage intervention (30 days post-injection) markedly upregulated COL1A1 expression through the TGF-β/Smad3 pathway activation, outperforming poly-l-lactic acid (PLLA) in collagen deposition. Histological analysis revealed 23.4% greater dermal thickness in DuCol-treated groups compared to PLLA at 90 days. While PLLA exhibited sustained collagen stimulation beyond 90 days, DuCol exhibited superior early-phase efficacy (p < 0.001) with comparable safety profiles (no inflammatory response observed through 180-day monitoring). The combinatorial PLLA/DuCol (P&C) formulation synergistically enhanced dermal regeneration, achieving a 31.7% thicker collagen matrix than monotherapy groups. These results underscore the potential of DuCol as a novel implantable filler material for skin repair and regeneration.

Bifunctional collagen fibers-based porous material for integrated purification of oily seawater

Desalination has long been a critical strategy to address the global shortage of freshwater resources. However, the purification of oily seawater introduces additional complex challenges. This study presents the development of an eco-friendly, collagen fibers-based porous material (CFsPM), fabricated by binding collagen fibers with hydroxypropyl methylcellulose as a sustainable adhesive. Subsequently, Fe3 +-tannic acid coordination system was introduced into the collagen fibers to prepare a bifunctional porous material (Fe3+-P@CFsPM), designed for both emulsion separation and solar-driven seawater desalination. The coordination and hydrogen bonding interactions between the Fe3+-tannic acid complex and the -COOH/-OH/-NH2 groups of CFs, as well as the phenolic -OH groups of tannic acid, established stable cross-linked networks that enhanced the material's mechanical properties. Fe3+-P@CFsPM demonstrated outstanding performance in separating oil-in-water emulsions, with a separation flux exceeding 5500 L·m-2·h-1 and separation efficiency greater than 99.95%, owing to its superwettability in air and superoleophobicity in water. The hierarchical fibrous structure and the formation of the dark coordination complex within the collagen fibers significantly boosted the photothermal conversion efficiency of Fe3+-P@CFsPM. With the excellent self-desalting capability benefited from the superhydrophilicity and hierarchical transport properties, Fe3+-P@CFsPM maintained a superior evaporation rate (> 1.50 kg·m-2·h-1) for solar-driven evaporation of both low- and high-salinity seawater under 1.0 sun irradiation, with the produced fresh water meeting WHO standards. This bifunctional porous material, derived from collagen fibers, provides an integrated solution for oily seawater purification and presents a novel approach for the high-value utilization of collagen fibers.

Advanced collagen-based scaffolds for cartilage and osteochondral regeneration: A review

Osteoarthritis (OA), a prevalent degenerative joint disease, presents a formidable challenge to human health due to its complex pathophysiology. Despite various clinical treatments, a definitive cure for OA remains elusive, leaving patients with only symptomatic relief. Tissue engineering has emerged as a promising approach for OA treatment, offering the potential to restore damaged cartilage and osteochondral tissues. Collagen-based scaffolds, renowned for their superior biocompatibility and bioactivity, hold significant potential in promoting effective cartilage and osteochondral regeneration. Over the past decades, substantial progress has been made in the design and clinical translation of collagen-based scaffolds for cartilage and osteochondral tissue engineering. However, no comprehensive review has yet addressed the application of collagen scaffold materials for OA treatment. This review highlights the advanced fabrication of collagen-based scaffolds, including porous matrices, hydrogels, and microspheres, and their integration with cells, growth factors, and pharmaceuticals for OA therapy. Additionally, it examines the clinical translation of collagen-integrated constructs for managing OA. With continued innovation, collagen-enriched scaffolds are expected to play a pivotal role in improving outcomes for OA patients.

Impact of Culture Duration on the Properties and Functionality of Yeast-Derived Extracellular Vesicles

Extracellular vesicles (EVs), lipid bilayer nanovesicles secreted by cells, carry nucleic acids, proteins, and other bioactive molecules that influence recipient cells and modulate various biological processes. This study investigated how energy depletion and fermentation processes influence the characteristics and physiological functions of EVs secreted by Saccharomyces cerevisiae. Specifically, we analyzed EVs derived from 24-h cultures, representing the glucose utilization phase, and 72-h cultures, representing the starvation stage. Under energy-depleted conditions (72-h cultures), yeast secreted a higher number of EV particles, albeit with a smaller average particle size. In contrast, EVs from yeast cultured for 24 h, during the glucose utilization phase, were enriched in Pep12-rich endosome-derived vesicles and exhibited 71% higher cellular internalization efficiency. Proteomic and transcriptomic analyses revealed distinct protein and microRNA profiles between EVs from 24- and 72-h cultures, highlighting their potential roles in tissue regeneration, cell proliferation, and collagen synthesis. As a result, EVs derived from 24-h cultures exhibited a 15% greater effect in promoting collagen synthesis. The differential effects on collagen production may be attributed to the efficiency of endocytosis and the specific protein and microRNA cargo of the EVs. This study emphasizes the functional potential and unique properties of yeast-derived EVs while proposing strategies to modulate EV composition by adjusting the yeast culture duration and the energy source in the medium. Further research is needed to control yeast-produced EV components and to understand their mechanisms of action for effective therapeutic applications.

The environmental impact of extracellular matrix preparation

The extracellular matrix (ECM) is a network of proteins and other molecules that encase and support cells and tissues in the body. As clinical and biotechnological uses of ECM are expanding, it is essential to assess the environmental impact associated with its production. Due to high levels of customization, various laboratories employ distinct methods; therefore, this study evaluates three common protocols. Life cycle assessment (LCA) methodology has been developed to evaluate the environmental impacts of products produced through diverse processes. Despite its widespread application in the pharmaceutical industry, LCA has seldom been utilized to estimate the environmental effects of laboratory protocols. This Viewpoint applies LCA to assess the functionality and environmental impacts of ECM produced via P1, P2, and P3. The results of this assessment indicate that the protocol with the highest impact generates approximately 43 times more CO2-equivalent emissions (CO2 eq) than that with the lowest impact, while the ECM produced using the least impactful protocol demonstrates the highest biocompatibility. Additional environmental indicators such as eutrophication, photochemical oxidation, and acidification also vary among the tested protocols. This work underscores the need to factor environmental impact in the development of novel biomedical materials.

Food Safety Evaluation of Recombinant Humanized Type III Collagen Produced by Komagataella phaffii SMD1168-2COL3

Collagens are biofunctional proteins that have been widely used in many fields, including biomedical, cosmetics, and skin care for their value in maintaining the integrity of cellular membranes. Collagens are also commonly consumed in foods and provide a source of protein and amino acids. As part of the safety assessment for this particular recombinant humanized type III (RHTypeIII) collagen produced by Komagataella phaffii SMD1168-2COL3, a series of toxicological tests were conducted. This collagen has ≥ 90% amino acid sequence homology to bovine and porcine collagen. The RHTypeIII collagen showed no evidence of genotoxic potential in a battery of tests. It was not toxic in an acute oral study, with no effects at 10 g/kg BW. The RHTypeIII collagen was not developmentally toxic in Sprague Dawley (SD) rat, and the NOAEL was 4.5 g/kg BW/day. In a 90-day oral gavage study in rats, there were no adverse findings observed; therefore, the high dose level (4.5 g/kg BW/day) was considered the NOAEL. The protein sequence was subjected to homology searches against the AllergenOnline database (sliding 80-amino acid windows and full sequence searches). From the 80-amino acid alignment searches, 23 significant matches were identified (> 35% identity and E value < 1 × 10-7) to allergens of bovine, fish, anisakis, feverfew pollen, ragweed pollen, and wheat origin. Although matches were identified, further assessment of the in silico results combined with a literature review demonstrates that the risk of allergenic cross-reactivity for this collagen is low. These results demonstrate RHTypeIII collagen is not toxic and unlikely to present a risk of allergy when used as a food ingredient.

3D Bioprinting Models for Glioblastoma: From Scaffold Design to Therapeutic Application

Conventional in vitro models fail to accurately mimic the tumor in vivo characteristics, being appointed as one of the causes of clinical attrition rate. Recent advances in 3D culture techniques, replicating essential physical and biochemical cues such as cell-cell and cell-extracellular matrix interactions, have led to the development of more realistic tumor models. Bioprinting has emerged to advance the creation of 3D in vitro models, providing enhanced flexibility, scalability, and reproducibility. This is crucial for the development of more effective drug treatments, and glioblastoma (GBM) is no exception. GBM, the most common and deadly brain cancer, remains a major challenge, with a median survival of only 15 months post-diagnosis. This review highlights the key components needed for 3D bioprinted GBM models. It encompasses an analysis of natural and synthetic biomaterials, along with crosslinking methods to improve structural integrity. Also, it critically evaluates current 3D bioprinted GBM models and their integration into GBM-on-a-chip platforms, which hold noteworthy potential for drug screening and personalized therapies. A versatile development framework grounded on Quality-by-Design principles is proposed to guide the design of bioprinting models. Future perspectives, including 4D bioprinting and machine learning approaches, are discussed, along with the current gaps to advance the field further.

Mechanisms of gel formation in collagen/hydroxypropyl methylcellulose aqueous mixtures below the threshold for macroscopic phase separation

The gelation mechanisms of aqueous collagen/hydroxypropyl methylcellulose (HPMC) mixtures were investigated below the macroscopic phase separation threshold. This study examines the interactions between collagen and HPMC, the phase behavior, and the resulting gel and structural properties. The results indicate that at low mixing concentrations, hydrogen bonding between collagen and HPMC, along with excluded volume effects, induces microscopic phase separation under partially phase-compatible conditions. As the HPMC concentration increases, the phase morphology transitions from a collagen-dominant phase to an HPMC-dominant phase, accompanied by enhanced hydrogen bonding between the two components. Gel formation in these mixtures follows a two-step gelation process, with HPMC influencing gelation kinetics. The excluded volume effect results in collagen concentration, while an optimal HPMC concentrations facilitates the entanglement of collagen chains, promoting the formation of α-helix, β-turn, and antiparallel β-sheet conformations, and ordered triple-helix structures, thereby enhancing gel properties. However, at excessively high HPMC concentrations, excessive hydrogen bonding and excluded volume effects hinder the formation of triple-helix structures, leading to a gel network with reduced mechanical properties. This study highlights the critical role of HPMC concentration in modulating collagen gel formation and provides insights into the complex interactions governing gelation in protein-polysaccharide systems.

The culture and application of circulating tumor cell-derived organoids

Circulating tumor cells (CTCs), which have the heterogeneity and histological properties of the primary tumor and metastases, are shed from the primary tumor and/or metastatic lesions into the vasculature and initiate metastases at remote sites. In the clinic, CTCs are used extensively in liquid biopsies for early screening, diagnosis, treatment, and prognosis. Current research focuses on using CTC-derived models to study tumor heterogeneity and metastasis, with 3D organoids emerging as a promising tool in cancer research and precision oncology. However, isolating and enriching CTCs from blood remains challenging due to their scarcity, exacerbated by the lack of an optimized culture medium for CTC-derived organoids (CTCDOs). In this review, we summarize the origin, isolation, enrichment, culture, validation, and clinical application of CTCs and CTCDOs.

Development of hyaluronic acid-based hydrogels for chronic diabetic wound healing: A review

This research delves into the advancements in chronic skin wound treatment, with a particular focus on diabetic foot ulcers, utilizing hyaluronic acid (HA)-based hydrogels. Hyaluronic acid, an integral component of the skin's extracellular matrix, plays a crucial role in process such as inflammation, angiogenesis, and tissue regeneration. Due to their three-dimensional network structure, biocompatibility, hydrophilicity, and gas exchange capabilities, HA-based hydrogels are considered highly suitable for promoting wound healing. Nonetheless, pure HA hydrogels exhibit limitations including insufficient mechanical strength and rapid release of encapsulated substances. To address these limitations, the incorporation of bioactive materials such as chitosan and collagen was investigated. This combination not only optimized mechanical strength and degradation rates but also enhanced antibacterial and anti-inflammatory properties. Furthermore, responsive hydrogel dressings were developed to adapt to the specific characteristics of the diabetic wound microenvironment, enabling on-demand drug release. These advancements present new perspectives for the treatment of diabetic foot ulcers.

Sequential activation of osteogenic microenvironment via composite peptide-modified microfluidic microspheres for promoting bone regeneration

The osteogenic microenvironment (OME) significantly influences bone repair; however, reproducing its dynamic activation and repair processes remains challenging. In this study, we designed injectable porous microspheres modified with composite peptides to investigate cascade alterations in OME and their underlying mechanisms. Poly l-lactic acid microfluidic microspheres underwent surface modifications through alkaline hydrolysis treatment, involving heterogeneous grafting of bovine serum albumin nanoparticles with stem cell-homing peptides (BNP@SKP) and BMP-2 mimicking peptides (P24), respectively. These modifications well-organized the actions of initial release and subsequent in situ grafting of peptides. Cellular experiments demonstrated varied degrees of chemotactic recruitment and osteogenic differentiation in mesenchymal stem cells. Further biological analysis revealed that BNP@SKP targeted the Ras/Erk axis and upregulated matrix metalloproteinase (MMP)2 and MMP9 expression, thereby enhancing initial chemotaxis and recruitment. In vivo studies validated the establishment of a dynamically regulated OME centered on the microspheres, resulting in increased stem cell recruitment, sequential activation of the differentiation microenvironment, and facilitation of in situ osteogenesis without ectopic ossification. In conclusion, this study successfully fabricated composite peptide-modified microspheres and systematically explored the mechanisms of bone formation through sequential activation of OME via heterogeneous grafting of signaling molecules. This provides theoretical evidence for biomaterials based on microenvironment regulation.

Imaging Interstitial Fluids and Extracellular Matrix in Cerebrovascular Disorders: Current Perspectives and Clinical Applications

This article provides a comprehensive review of current neuroimaging techniques for visualizing and quantifying extracellular matrix (ECM) components and interstitial fluid (ISF) dynamics in cerebrovascular disorders. It examines how alterations in ECM composition and ISF movement patterns correlate with various cerebrovascular pathologies, including ischemic stroke, frontotemporal dementia, cerebral small vessel disease, Alzhheimer's disease, and vascular dementia. The review emphasizes novel imaging markers specific to ECM/ISF alterations and their utility in differentiating various cerebrovascular pathologies. Special attention is given to the clinical applications of these imaging techniques for early disease detection, monitoring progression, and guiding therapeutic interventions.

Advances in 3D-printed scaffold technologies for bone defect repair: materials, biomechanics, and clinical prospects

The treatment of large bone defects remains a significant clinical challenge due to the limitations of current grafting techniques, including donor site morbidity, restricted availability, and suboptimal integration. Recent advances in 3D bioprinting technology have enabled the fabrication of structurally and functionally optimized scaffolds that closely mimic native bone tissue architecture. This review comprehensively examines the latest developments in 3D-printed scaffolds for bone regeneration, focusing on three critical aspects: (1) material selection and composite design encompassing metallic; (2) structural optimization with hierarchical porosity (macro/micro/nano-scale) and biomechanical properties tailored; (3) biological functionalization through growth factor delivery, cell seeding strategies and surface modifications. We critically analyze scaffold performance metrics from different research applications, while discussing current translational barriers, including vascular network establishment, mechanical stability under load-bearing conditions, and manufacturing scalability. The review concludes with a forward-looking perspective on innovative approaches such as 4D dynamic scaffolds, smart biomaterials with stimuli-responsive properties, and the integration of artificial intelligence for patient-specific design optimization. These technological advancements collectively offer unprecedented opportunities to address unmet clinical needs in complex bone reconstruction.

Squid Skin Decellularised Dermal Matrix for Enhancing Repair of Acute Cranial Injuries in Rabbit Model

Squid skin decellularized dermal matrix (SADM) is gaining attention in tissue engineering and regenerative medicine due to its mimicking of the extracellular matrix property. Hence, SADM was used to investigate mimicking the microenvironment of cellular growth, inducing cellular infiltration and angiogenesis, and facilitating the repair of acute craniofacial wounds. For this, tissue regeneration membranes from squid skin were prepared by decolorization, degreasing and decellularisation methods. The effect of SADM in guiding bone tissue regeneration was evaluated using the rabbit skull bone defect model. SEM images of SADM had a bilayer membrane architecture characterized by a reticulated porous structure on one side and a dense, non-porous surface on the opposite side. Notably, the water absorption capacity of SADM was approximately eight times higher than its weight, exhibiting a porosity of 58% and a peak average tensile stress of 10.43 MPa. Additionally, simulations of tissue fluid degradation indicated a degradation rate of 70.42% and 88.33% on days 8 and 12, respectively. Following 4 and 8 weeks of animal studies focused on repairing cranial bone defects in rabbits, the findings demonstrated that SADM served as an effective barrier against fibrous connective tissue, promoted the proliferation of osteoblasts, and supported bone regeneration. This was confirmed through micro-CT imaging, and sections were stained with senna solid green. In summary, SADM is capable of directing cell infiltration and bone tissue formation, modulating the expression and secretion of inflammatory and skin repair-related factors, thereby enhancing tissue healing.

Expression, optimization and biological activity analysis of recombinant type XII collagen in Pichia pastoris

Collagen XII (COL12A1) is a type of FACIT collagen that plays an important role in the extracellular matrix structuring, participating in the regulation of collagen fiber size, and serves as a link between different components of the extracellular matrix. However, it is still unclear whether exogenous administration of collagen XII has a direct regulatory effect. In this study, we successfully produced recombinant human XII-type collagen (rh12C) through genetic engineering approach, which is composed of different functional domains. A Pichia pastoris host cell strain was constructed based on the intracellular translation regulatory mechanism of collagen, achieving a maximum yield of 4.89 g/L. After purification and structural characterization of the protein, its potential biological efficacy was evaluated through in vitro cell experiments.

Targeting tumor extracellular matrix with nanoparticles to circumvent therapeutic resistance

Each stage of tumor development is intrinsically linked to the tumor microenvironment (TME), wherein the extracellular matrix (ECM) serves as a vital and abundant component in tumor tissues. The ECM is a non-cellular, three-dimensional macromolecular network scaffold that provides structural support to cells, stores bioactive molecules, and mediates signaling pathways through specific binding to cell surface receptors. Moreover, the ECM in tumor tissues plays a crucial role in impeding drug diffusion and resisting apoptosis induced by conventional anti-cancer therapies that primarily target cancer cells. Therefore, directing attentions towards the tumor ECM can facilitate the identification of novel targets and the development of new therapies. This review aims to summarize the composition, structure, remodeling, and function of tumor ECM, its association with drug resistance, and current targeting strategies, with a specific emphasis on nanoparticles (NPs).

Structural and functional analysis of a homotrimeric collagen peptide

Objective

This study aimed to chemically synthesize a homotrimeric collagen peptide, evaluate its safety, and assess its effectiveness in promoting collagen synthesis.

Methods

A homotrimeric collagen peptide was synthesized and structurally characterized using circular dichroism and infrared spectroscopy. Thermal stability was analyzed by TG-DSC, and molecular weight and amino acid composition were determined. In vitro cytotoxicity testing assessed safety, while UV-induced photoaging experiments evaluated its effects on collagen and elastin synthesis. In vivo studies in BALB/c mice examined its impact on collagen content, skin structure, and angiogenesis.

Results

The synthesized collagen peptide exhibited high purity (99.1%) and an amino acid composition of glycine, proline, and hydroxyproline in a balanced ratio (15:17:13). Structural analysis confirmed a stable triple-helical conformation similar to type I collagen with excellent thermal stability (Tm = 326.15°C). Cytotoxicity testing showed no adverse effects on cell viability. In vitro, the peptide significantly enhanced collagen and elastin synthesis in fibroblasts. In vivo, intradermal and subcutaneous injection increased collagen content, improved skin structure, and enhanced microvessel density.

Conclusion

This study presents a chemically synthesized homotrimeric collagen peptide with superior purity, structural stability, and biological efficacy in promoting collagen synthesis. Compared to previous studies, this biomimetic material exhibits exceptional thermal stability (Tm = 326.15°C) and a well-balanced amino acid composition, enabling applications in cosmetics and medical devices requiring heat sterilization (e.g., autoclaving), as validated by our patented method (China Patent No. ZL202410309842.9).

Binding of collagen I to integrins alleviates UVB-caused mitochondrial disorders in human keratinocytes HaCaT through enhancement of F-actin polymerization

Collagen I is one of the major components of the extracellular matrix in human skin, and is frequently used in skin cares and medications. Previously, we revealed that human keratinocytes HaCaT cells grown on collagen I (Col)-coated dishes gain resistance against UVB damages owing to the restored mitophagy. In this study, we further investigate the mechanisms by which collagen I modulates mitophagy. UVB irradiation causes loss of integrin β1 and collapse of F-actin cytoskeleton. Considering the requirement of actin skeleton in various cellular processes, we are curious about the participation of F-actin collapse in UVB damage. Integrin β1, whose activation enhances F-actin assembly, is a potential target for Col in UVB-treated cells. Notably, inhibiting integrin by adding an inhibitor RGDS or siRNA attenuates the effect of Col against UVB damages, confirming the participation of integrin in cell protection. The collapse of F-actin is rescued by Col, accompanying increases in the mRNA of F-actin polymerization-associated proteins and decreases in the mRNA of depolymerization-associated proteins. Inhibiting actin polymerization by using cytochalasin D represses the protective effect of Col, confirming the cytoprotective role of F-actin in UVB-treated cells. Remarkably, mitophagy in UVB-treated cells restored by Col-coating is inhibited by adding cytochalasin D or RGDS, as shown by the decreases of lysosomes, mitochondrial ubiquitin proteins, and co-localization of autophagosomes and mitochondria, resulting in accumulation of damaged mitochondria, which stresses the importance of F-actin and integrin in mitophagy. In summary, integrins and F-actin are required for mitophagy in UVB-irradiated HaCaT cells, and their enhancements by Col-coating facilitate timely elimination of damaged mitochondria caused by UVB, finally contributing to cell survival.

Recent Advances in the Development and Application of Cell-Loaded Collagen Scaffolds

Tissue engineering techniques aim to improve or replace biological tissues or organs by utilizing the extracellular matrix to facilitate the repair of damaged tissues or organs. Collagen-based scaffolds offer numerous advantages, including excellent biocompatibility, low immunogenicity, biodegradability, hemostatic properties, and mechanical strength. Collagen scaffolds can reconstruct the extracellular microenvironment, promote cell adhesion, migration, proliferation, and differentiation, and play a critical role in cell-to-cell and cell-to-matrix interactions. Collagen has been extensively utilized in tissue engineering to facilitate tissue repair and organ reconstruction. This review examines the properties of collagen, including its composition, structure, biological characteristics, and role in regulating various cellular behaviors. Additionally, the preparation of cell-loaded collagen scaffolds is discussed, along with a comprehensive overview of their applications in various tissues, including skin, nerve, bone/cartilage, heart, liver, and others. Emerging strategies and future perspectives for clinical tissue repair are also presented. This review provides a comprehensive synthesis of the mechanisms underlying the use of cell-loaded collagen scaffolds as advanced biomaterials, emphasizing their potential to expand the clinical applications of collagen.

Hierarchical Assemblies of Collagen-Mimetic Peptides: From a Fundamental Understanding to Developing Biomaterials

Collagen is the most abundant protein in animals and crucial for maintaining the structural and functional integrity of the extracellular matrix. Its primary structure consists of ∼300 repeats of the Xaa-Yaa-Gly triplet, where Xaa and Yaa are often proline (Pro) and 4-(R)-hydroxyproline (Hyp) residues, respectively. Collagen is fundamentally a right-handed triple helix that undergoes self-association, forming complex supramolecular structures in the body. Despite extensive study, the detailed mechanisms behind its higher-order assembly remain unclear due to challenges in its purification and the extensive post-translational modifications that it undergoes. To better understand the molecular aspects of collagen's complex structure, researchers developed collagen-mimetic peptides (CMPs)─short peptides composed of 7-17 Xaa-Yaa-Gly triplets─easily synthesized in the laboratory. Over the years, research on CMPs has provided significant insights into the formation and stability of the collagen triple helix. However, creating multihierarchical self-assembled structures beyond the triple helix remains challenging. Recently, various strategies such as covalent linkages, salt-bridge interactions, incorporation of hydrophobic groups, metal-coordinated assembly, and coassembly with foreign partners have been employed to design higher-order CMP assemblies. These innovations have led to the creation of fibers, 2D sheets, wires, and spherical micelles. This progress has paved the way for the rational design of novel peptide-based biomaterials, which may offer advantages over animal-derived collagen, including the absence of potential allergens and contaminants. This review highlights recent advancements in CMP assembly design, discussing the principles, challenges, and prospects of these biomaterials in clinical applications.

Hyperstable and Fibril-Forming Collagen-Mimetic Peptides in Shortest Triple Helices: Empowering the Capping by π-systems

Developing collagen-mimetic peptides (CMPs) with short triple helices and fibril-forming ability remains challenging. Herein, we stabilized short CMPs (3-6 GPO repeats) by attaching extended aromatic π-system─fluorenyl groups at the N-terminus and tyrosine at the C-terminus. These modifications promoted triple helix folding through π-π interactions, acting as a "glue" to stabilize the structure and facilitate fibrillation. A single fluorenyl cap required 5 GPO repeats for helix formation, while double fluorenyl capping reduced this to 4 repeats. Notably, at pH 5.5, triple helices formed with only 3 GPO repeats. The double-capped CMPs exhibited hyperstability (Tm = 76 °C) and formed fibrillar networks at physiological pH. Biophysical and computational studies confirmed the role of π-π and CH-π interactions, along with hydrogen bonding, in stabilization. The minimalistic CMPs supported cell viability, demonstrating their potential for biomedical applications. This strategy offers a method to design highly stable, short CMPs that form robust fibrillar networks.

Establishing a Bioink Assessment Protocol: GelMA and Collagen in the Bioprinting of a Potential In Vitro Intestinal Model

Collagen and gelatin methacryloyl (GelMA) are widely studied biomaterials for extrusion-based bioprinting (EBB) due to their excellent biological properties and ability to mimic the extracellular matrix of native tissues. This study aims to establish a preliminary workflow for approaching EBB by assessing collagen and GelMA printability and biological performance. GelMA was selected for its cost-effectiveness and ease of synthesis, while our collagen formulation was specifically optimized for printability, which is a challenging aspect of bioprinting. A parallel evaluation of their printability and biological performance is provided to develop a preliminary 3D intestinal model replicating the submucosa, lamina propria, and epithelial layer. Rheological analyses demonstrated that both materials exhibit a shear-thinning behavior. Collagen (u-CI) displayed a shear-thinning parameter p = 0.1 and a consistency index C = 80.62 Pa·s, while GelMA (u-GI) exhibited a more pronounced shear-thinning effect and enhanced shape retention (p = 0.06, C = 286.6 Pa·s). Post-extrusion recovery was higher for collagen (85%), compared to GelMA (45%), indicating its greater mechanical resilience. Photo-crosslinking improved hydrogel stability, with an increase in storage modulus G' for both materials. Printing tests confirmed the suitability of both hydrogels for bioprinting, with GelMA demonstrating higher print fidelity than collagen. Dimensional stability assessments under incubating conditions revealed that collagen constructs maintained their shape for 14 days before degradation, whereas GelMA constructs exhibited a gradual decrease in diameter over 21 days. Cell culture studies showed that human skin fibroblasts (HSFs) and human colon adenocarcinoma cells (HCT-8) could be successfully cocultured in an optimized RPMI 1640-based medium. AlamarBlue assays and Live/Dead staining confirmed high cell viability and proliferation within both hydrogel matrices. Notably, HSFs in GelMA exhibited more elongated morphologies, likely due to the material's lower stiffness (380 Pa) compared to collagen (585 Pa). HCT-8 cells adhered more rapidly to GelMA constructs, forming colonies within 7 days, whereas on collagen, colony formation was delayed to 14 days. Finally, a layered intestinal model was fabricated, and immunostaining confirmed the expression of tight junction (ZO-1) and adhesion (E-cadherin) proteins, validating the epithelial monolayer integrity. These findings highlight the potential of collagen and GelMA in 3D bioprinting applications for gut tissue engineering and pave the way for future developments of in vitro intestinal models.

Fabrication and applications of biofunctional collagen biomaterials in tissue engineering

Collagen is extensively used in tissue engineering for various organ tissue regeneration due to the main component of human organ extracellular matrix (ECM) and their inherent nature bioactivity. Collagen various types naturally exist in different organ ECMs. Collagen fabricated with natural ECM mimics architecture, composition and mechanical properties for various organ tissue regeneration. Collagen fabrication with organ-specific biofunctionality facilitated organ tissue engineering as compared to unmodified collagen biomaterials. Collagen biofunctionality improved by subjecting collagen to synthesis, fibers and surface modifications, and blending with other components. Furthermore, collagen is loaded with bioactive molecules, growth factors, drugs and cells also enhancing the biofunctionality of collagen biomaterials. In this review, we will explore the recent advancements in biofunctional collagen biomaterials fabrication with organ-specific biofunctionality in tissue engineering to resolve various organ tissue engineering issues and regeneration challenges. Biofunctional collagen biomaterials stimulate microenvironments inside and around the implants to excellently regulate cellular activities, differentiate cells into organ native cells, enhanced ECM production and remodeling to regenerate organ tissues with native structure, function and maturation. This review critically explored biofunctional collagen biomaterials fabrication in resolving various organ tissue engineering issues and regeneration challenges, and opening new directions of biofunctional collagen biomaterials fabrication, design and applications.

Assessing New Collagen Therapies for Wound Healing: A Murine Model Approach

Collagen proteins play important roles in wound healing and are of great interest in regenerative medicine. This study evaluated the efficacy of new collagen-based products and compared them to commercial products in a murine model of cutaneous healing. Circular excisional defects were generated on 72 Wistar rats. Six study groups were established according to the administered collagen treatment: Control (without treatment), SD-C (semidenatured), Catrix, Hy-C (hydrolyzed), N-C (native) and Helix3-CP. Seven and eighteen days post-surgery, animals were euthanized. Wound closure was macroscopically assessed by taking zenithal images of the defects. Morphological, histological and immunohistochemical studies were performed to evaluate the healing process. After 7 days, open areas and degree of epithelialization were similar among the groups. Significant differences were observed in contraction between control and the N-C and Helix3-CP groups. Untreated animals exhibited a more pronounced granulation tissue with a high number of inflammatory cells and a disorganised extracellular matrix with type III collagen deposition. After 18 days, animals treated with new collagen (Hy-C and N-C) exhibited accelerated wound closure, increased epithelialization and a more organised granulation tissue. Local administration of new collagen treatments promotes the progression of the reparative process and significantly accelerates wound closure compared with nontreated wounds.

Hydrogels as drug delivery platforms for orthopedic diseases treatment: A review

The skeletal system serves as a crucial support structure for the human body, any damage or disease to bones can result in prolonged pain, impaired mobility, and other negative outcomes. For the treatment of bone diseases, with the in-depth study of the therapeutic mechanism, various small molecule drugs, cells, cytokines, growth factors, bioactive ions, collectively referred to as "drugs" in this context, are increasingly investigated for their potential application in surgical procedures, defect repair, or treatment of diseased bone regions. However, various challenges, including, low stability, the necessity for precise dosage control, are encountered in the administration of drugs. Consequently, the advancement of drug delivery platforms is crucial to safeguard drug efficacy and address the requirement for dosage regulation. Given the attributes of current drug delivery platforms, hydrogels exhibit favorable biocompatibility and offer the ability to easily regulate drug loading and release. As a carrier with diverse properties, abundant varieties, optimal performance, hydrogels present a promising solution in drug delivery. This paper aims to analyze the potential of hydrogel as a delivery platform for treating orthopedics diseases by reviewing the characteristics of hydrogel delivery systems, mechanisms of drug binding, current research findings, and projecting future developments in this field.

Collagen Hydrolysates from Animal By-Products in Topical Cosmetic Formulations

The circular economy of animal by-products rich in collagen focuses on converting collagen into peptides with a defined molecular weight. Collagen hydrolysates prepared by biotechnological methods from chicken gizzards, deer tendons, and Cyprinus carpio skeletons can be an alternative source of collagen for cosmetic products that traditionally use bovine or porcine collagen hydrolysates. Collagen hydrolysates were characterized by antioxidant activity, surface tension, solution contact angle, and other parameters (dry weight, ash content, and solution clarity). Furthermore, the vibrational characterization of functional groups and their molecular weight was performed using the GPC-RID method. Subsequently, emulsion and gel cosmetic matrices were prepared with 0.5% and 1.5% collagen hydrolysates. Microbiological stability, organoleptic properties, and viscosity were investigated. Verification of the biophysical parameters of the topical formulations was performed in vivo on a group of volunteers by measuring skin hydration and pH and determining trans-epidermal water loss. Fish collagen hydrolysate was the most suitable for cosmetic applications in the parameters investigated. Moreover, it also effectively reduces wrinkles in the periorbital region when used in a gel matrix.

Collagen Hybridizing Peptides Promote Collagen Fibril Growth In Vitro

Recreating the structural and mechanical properties of native tissues in vitro presents significant challenges, particularly in mimicking the dense fibrillar network of extracellular matrixes such as skin and tendons. This study develops a reversible collagen film through cycling collagen self-assembly and disassembly, offering an innovative approach to address these challenges. We first generated an engineered collagen scaffold by applying plastic compression to the collagen hydrogel. The reversibility of the collagen assembly was explored by treating the scaffold with lactic acid, leading to its breakdown into an amorphous gel─a process termed defibrillogenesis. Subsequent immersion of this gel in phosphate buffer facilitated the reassembly of collagen into fibrils larger than those in the original scaffold yet with the D-banding pattern characteristic of collagen fibrils. Transfer learning of the mobileNetV2 convolutional neural network trained on atomic force microscope images of collagen nanoscale D-banding patterns was created with 99% training and testing accuracy. In addition, extensive external validation was performed, and the model achieved high robustness and generalization with unseen data sets. Further innovation was introduced by applying collagen hybridizing peptides, which significantly accelerated and directed the assembly of collagen fibrils, promoting a more organized and aligned fibrillar structure. This study not only demonstrates the feasibility of creating a reversible collagen film that closely mimics the density and structural properties of the native matrix but also highlights the potential of using collagen hybridizing peptides to control and enhance collagen fibrillogenesis. Our findings offer promising tissue engineering and regenerative medicine strategies by enabling precise manipulation of collagen structures in vitro.

Unlocking the Potential of Marine Sidestreams in the Blue Economy: Lessons Learned from the EcoeFISHent Project on Fish Collagen

This review provides a general overview of collagen structure, biosynthesis, and biological properties, with a particular focus on marine collagen sources, especially fisheries discards and by-catches. Additionally, well-documented applications of collagen are presented, with special emphasis not only on its final use but also on the processes enabling sustainable and safe recovery from materials that would otherwise go to waste. Particular attention is given to the extraction process, highlighting key aspects essential for the industrialization of fish sidestreams, such as hygiene standards, adherence to good manufacturing practices, and ensuring minimal environmental impact. In this context, the EcoeFISHent projects have provided valuable insights, aiming to create replicable, systemic, and sustainable territorial clusters based on a multi-circular economy and industrial symbiosis. The main goal of this project is to increase the monetary income of certain categories, such as fishery and aquaculture activities, through the valorization of underutilized biomass.

Optimizing Flexor Digitorum Profundus Tendon Repair: A Narrative Review

Zone II flexor digitorum profundus (FDP) tendon injuries are complex, and present significant challenges in hand surgery, due to the need to balance strength and flexibility during repair. Traditional suture techniques often lead to complications such as adhesions or tendon rupture, prompting the exploration of novel strategies to improve outcomes. This review investigates the use of flexor digitorum superficialis (FDS) tendon autografts to reinforce FDP repairs, alongside the integration of biomaterials to enhance mechanical strength without sacrificing FDS tissue. Key biomaterials, including collagen-polycaprolactone (PCL) composites, are evaluated for their biocompatibility, mechanical integrity, and controlled degradation properties. Collagen-PCL emerges as a leading candidate, offering the potential to reduce adhesions and promote tendon healing. Although nanomaterials such as nanofibers and nanoparticles show promise in preventing adhesions and supporting cellular proliferation, their application remains limited by manufacturing challenges. By combining advanced repair techniques with biomaterials like collagen-PCL, this approach aims to improve surgical outcomes and minimize complications. Future research will focus on validating these findings in biological models, assessing tendon healing through imaging, and comparing the cost-effectiveness of biomaterial-enhanced repairs with traditional methods. This review underscores the potential for biomaterial-based approaches to transform FDP tendon repair.

Corneal first aid lens: Collagen-based hydrogels loading aFGF as contact lens for treating corneal injuries

Severe corneal injuries can cause visual impairment even blindness. Surgically stitching or implanting biomaterials have been developed, but their implementation requires professional surgeons, failing to address the immediate need of medical treatment. The pressing challenge lies in developing multifunctional biomaterials that enable self-management of corneal injuries. This study introduces collagen-based hydrogels that can be used as contact lenses, incorporating macromolecular collagen into common polymer materials via a dual-step orthogonal cross-linking process. This method ensures superior optical and mechanical performance while preserving the bioactivity and structural stability of the incorporated materials. Specialized contact lens facilitates the controlled release of labile protein therapeutics such as acidic fibroblast growth factor (aFGF), eliminating the need for stabilizers like heparin. This capability allows the lens to deliver a wide range of labile proteins, thus expanding its therapeutic use across various ophthalmic and potentially other medical conditions. The lens's anti-inflammatory and anti-fibrotic properties effectively treat corneal alkali burn. Termed 'corneal first-aids lens', it can provide postoperative clinical care and serve as a viable and safe therapeutic alternative for patients with limited medical access.

The role of various collagen types in tumor biology: a review

Collagen comprises approximately 30% of the body's protein content and is essential for maintaining the structural integrity, support, and strength of the skin, muscles, bones, and connective tissues. Recent research has further elucidated its role in various aspects of tumor biology, including tumorigenesis, invasion, migration, drug resistance, and recurrence. Furthermore, collagen is involved in prognostic assessments, the evaluation of therapeutic efficacy, immunoregulation, and the identification of potential treatment targets in oncology. This review examines a range of tumor types, including lung, gastric, breast, melanoma, and colorectal cancers, among others. Our objective is to differentiate these tumors based on the specific types of collagen present and to analyze the roles of various collagen types in tumor development, progression, prognosis, and their potential as therapeutic targets.

The pharmacology of vitamin C

Ascorbic acid, the reduced form of vitamin C, is a ubiquitous small carbohydrate. Despite decades of focused research, new metabolic functions of this universal electron donor are still being discovered and add to the complexity of our view of vitamin C in human health. Although praised as an unsurpassed water-soluble antioxidant in plasma and cells, the most interesting functions of vitamin C seem to be its roles as specific electron donor in numerous biological reactions ranging from the well-known hydroxylation of proline to cofactor for the epigenetic master regulators ten-eleven translocation enzymes and Jumonji domain-containing histone-lysine demethylases. Some of these functions may have important implications for disease prevention and treatment and have spiked renewed interest in, eg, vitamin C's potential in cancer therapy. Moreover, some fundamental pharmacokinetic properties of vitamin C remain to be established including if other mechanisms than passive diffusion governs the efflux of ascorbate anions from the cell. Taken together, there still seems to be much to learn about the pharmacology of vitamin C and its role in health and disease. This review explores new avenues of vitamin C and integrates our present knowledge of its pharmacology. SIGNIFICANCE STATEMENT: Vitamin C is involved in multiple biological reactions of which most are essential to human health. Hundreds of millions of people are considered deficient in vitamin C according to accepted guidelines, but little is known about the long-term consequences. Although the complexity of vitamin C's physiology and pharmacology has been widely disregarded in clinical studies for decades, it seems clear that a deeper understanding of particularly its pharmacology holds the key to unravel and possibly exploit the potential of vitamin C in disease prevention and therapy.

Collagen as a biomaterial for skin wound healing: From structural characteristics to the production of devices for tissue engineering

Collagen is an abundant component in the human body and plays a fundamental role in the integrity and function of various tissues, including skin, bones, joints, and connective tissues. This natural polymer also contributes to physiological balance and individual health. Within this context, this article reviews the structure of collagen, describing intrinsic characteristics that range from its molecular composition to its organization into bundles. Additionally, the review highlights some of the applications of collagen in tissue engineering, particularly its mimicry of the skin's extracellular matrix. For this review, searches were performed in PubMed, Scopus, and Web of Sciences. The inclusion criteria were established based on the relevance of the studies for the objectives of the review and methodological quality. After selection of the articles, a critical analysis of their content was conducted and the information was synthesized and presented concisely. Analysis of the properties of collagen revealed its key importance for the design of bioactive materials in regenerative applications. However, challenges such as the need for improvement of the integration of implanted materials and a better understanding of the underlying biological processes remain.

Collagen remodeling-mediated signaling pathways and their impact on tumor therapy

In addition to their traditional roles in maintaining tissue morphology and organ development, emerging evidence suggests that collagen (COL) remodeling-referring to dynamic changes in the quantity, stiffness, arrangements, cleavage states, and homo-/hetero-trimerization of COLs-serves as a key signaling mechanism that governs tumor growth and metastasis. COL receptors act as switches, linking various forms of COL remodeling to different cell types during cancer progression, including cancer cells, immune cells, and cancer-associated fibroblasts. In this review, we summarize recent findings on the signaling pathways mediated by COL arrangement, cleavage, and trimerization states (both homo- and hetero-), as well as the roles of the primary COL receptors-integrin, DDR1/2, LAIR-1/2, MRC2, and GPVI-in cancer progression. We also discuss the latest therapeutic strategies targeting COL fragments, cancer-associated fibroblasts, and COL receptors, including integrins, DDR1/2, and LAIR1/2. Understanding the pathways modulated by COL remodeling and COL receptors in various pathological contexts will pave the way for developing new precision therapies.

Molecular Diffusion and Optical Properties of Implantable Collagen Materials

The effects of optical clearing of implantable collagen materials were studied using optical clearing agents (OCAs) based on aqueous glucose solutions of various concentrations. By measuring the kinetics of the collimated transmission spectra, the diffusion D and permeability P coefficients of the OCAs of collagen materials were determined as D = (0.22 ± 0.05) × 10-6 to (1.41 ± 0.05) × 10-6 cm2/c and P = (0.55 ± 0.04) × 10-4 to (1.77 ± 0.07) × 10-4 cm/c. Studies with optical coherence tomography (OCT) confirmed that each of the OCAs used had an effect on the optical properties of collagen materials, and allowed us to quantify the group refractive indices of the collagen of various samples, which turned out to be in the range from nc = 1.476 to nc = 1.579.

Influence of aerogel mechanical properties on collagen micromorphology and its architecture

Previously, we demonstrated the promise of aerogels for the repair of nerve injuries as neural cells extend longer processes (neurites) when grown on aerogels compared to a control surface. We also reported that the aerogel surface topography influenced neurite length. Neurite extension may be boosted by depositing collagen on the aerogel prior to plating the cells. Indeed, collagen has many applications in biomaterials for nerve repair because it profoundly influences cellular properties such as shape and motility. Using collagen to enhance neurite extension requires knowing the effect of collagen deposition on the aerogel surface profile as well as how the aerogel's surface topography influences collagen organization into fibers or films. Herein, we have examined by SEM and profilometry the reciprocal relationship between collagen micromorphology and aerogel surface features including pore diameters, surface roughness, and Young's modulus (Y). Using 5 types of aerogels differing from each other by these parameters, we show that increasing the collagen surface concentration from 4 to 20 μg cm-2 leads to a gradual transition in collagen architecture from discrete fibers to films where individual fibers were not discernible. The collagen surface concentration at which deposited collagen changes from filaments to films (transition point, T.P.) was strongly dependent on aerogel physical properties as it increased with increasing pore diameter and surface roughness, while Y had little effect. These results provide a practical framework to customize the organization of collagen fibers on scaffolds for biomedical applications.

Suture-Mediated Delivery System Reduces the Incidence of Uterine Scarring Through the TGF-β Pathway

In recent years, factors such as the postponement of childbearing and the relaxation of the childbearing policy have led to an increase in the proportion of cesarean sections and other intrauterine surgeries among pregnant women, further increasing the incidence of uterine scars. Currently, there is a lack of effective clinical treatment methods for uterine scars. In this study, a suture loaded with gene medicine was designed for the repair of uterine scars. Specifically, the non-viral vector Lipo8000 was first used to form a complex solution with the plasmid TGF-β3. Then, it was mixed and adsorbed with the surgical sutures pretreated with recombinant human type III collagen (RhCol III). In vitro experiments confirmed that RhCol III and the plasmid were successfully loaded onto the sutures and could be released and expressed. In vivo experiments were carried out using a rat model simulating uterine scars. The section results showed that compared with the scar model group, the expression level of TGF-β3 in the RhCol III+TGF-β3 group increased by 39%, the expression level of TGF-β1 decreased by 62.8%, and the fibrosis rate decreased by 16.8%, which has a positive effect on the prevention of uterine scars. This study integrates the therapeutic medicine into the sutures, ensuring that the medicine can come into contact with the wound site after suturing. Moreover, RhCol III and the gene medicine work synergistically to promote the repair of uterine wounds.

Advances in growth factor-containing 3D printed scaffolds in orthopedics

Currently, bone tissue engineering is a research hotspot in the treatment of orthopedic diseases, and many problems in orthopedics can be solved through bone tissue engineering, which can be used to treat fractures, bone defects, arthritis, etc. More importantly, it can provide an alternative to traditional bone grafting and solve the problems of insufficient autologous bone grafting, poor histocompatibility of grafts, and insufficient induced bone regeneration. Growth factors are key factors in bone tissue engineering by promoting osteoblast proliferation and differentiation, which in turn increases the efficiency of osteogenesis and bone regeneration. 3D printing technology can provide carriers with better pore structure for growth factors to improve the stability of growth factors and precisely control their release. Studies have shown that 3D-printed scaffolds containing growth factors provide a better choice for personalized treatment, bone defect repair, and bone regeneration in orthopedics, which are important for the treatment of orthopedic diseases and have potential research value in orthopedic applications. This paper aims to summarize the research progress of 3D printed scaffolds containing growth factors in orthopedics in recent years and summarize the use of different growth factors in 3D scaffolds, including bone morphogenetic proteins, platelet-derived growth factors, transforming growth factors, vascular endothelial growth factors, etc. Optimization of material selection and the way of combining growth factors with scaffolds are also discussed.

TMT-based quantitative proteomics reveals the genetic mechanisms of secondary hair follicle development in fine-wool sheep

The development of secondary hair follicles influences the quality of sheep wool. However, the mechanism by which proteins mediate the fetal development of secondary hair follicles remains unknown. In this study, the histomorphology of secondary hair follicles was analyzed over four stages of fetal development (75, 85, 95, and 105 gestational days). TMT-based quantitative proteomics was used to compare the differential protein profiles of skin tissues between consecutive developmental periods (75 versus 85, 85 versus 95, and 95 versus 105 gestational days). We found that the density of secondary hair follicles and the secondary hair follicles/primary hair follicles ratio increased from 85 to 105 gestational days. Bioinformatic analysis identified 238, 35, and 348 differentially expressed proteins in the respective comparison periods. Focal adhesion, ECM-receptor interaction, and the estrogen signaling pathway all played important roles in secondary hair follicle development. COL1A1, THBS3, ITGA6, COL6A1, and THBS4 were identified as potential candidate proteins in the initiation of secondary hair follicles. This study provides valuable proteomics data on secondary hair follicle development and thus has deepened our understanding of the molecular mechanisms underlying wool quality traits in fine-wool sheep.

Collagen as a bio-ink for 3D printing: a critical review

The significance of three-dimensional (3D) bioprinting in the domain of regenerative medicine and tissue engineering is readily apparent. To create a multi-functional bioinspired structure, 3D bioprinting requires high-performance bioinks. Bio-inks refer to substances that encapsulate viable cells and are employed in the printing procedure to construct 3D objects progressive through successive layers. For a bio-ink to be considered high-performance, it must meet several critical criteria: printability, gelation kinetics, structural integrity, elasticity and strength, cell adhesion and differentiation, mimicking the native ECM, cell viability and proliferation. As an exemplar application, tissue grafting is used to repair and replace severely injured tissues. The primary considerations in this case include compatibility, availability, advanced surgical techniques, and potential complications after the operation. 3D printing has emerged as an advancement in 3D culture for its use as a regenerative medicine approach. Thus, additive technologies such as 3D bioprinting may offer safe, compatible, and fast-healing tissue engineering options. Multiple methods have been developed for hard and soft tissue engineering during the past few decades, however there are many limitations. Despite significant advances in 3D cell culture, 3D printing, and material creation, a gold standard strategy for designing and rebuilding bone, cartilage, skin, and other tissues has not yet been achieved. Owing to its abundance in the human body and its critical role in protecting and supporting human tissues, soft and hard collagen-based bioinks is an attractive proposition for 3D bioprinting. Collagen, offers a good combination of biocompatibility, controllability, and cell loading. Collagen made of triple helical collagen subunit is a protein-based organic polymer present in almost every extracellular matrix of tissues. Collagen-based bioinks, which create bioinspired scaffolds with multiple functionalities and uses them in various applications, is a represent a breakthrough in the regenerative medicine and biomedical engineering fields. This protein can be blended with a variety of polymers and inorganic fillers to improve the physical and biological performance of the scaffolds. To date, there has not been a comprehensive review appraising the existing literature surround the use of collagen-based bioink applications in 'soft' or 'hard' tissue applications. The uses of the target region in soft tissues include the skin, nerve, and cartilage, whereas in the hard tissues, it specifically refers to bone. For soft tissue healing, collagen-based bioinks must meet greater functional criteria, whereas hard tissue restoration requires superior mechanical qualities. Herein, we summarise collagen-based bioink's features and highlight the most essential ones for diverse healing situations. We conclude with the primary challenges and difficulties of using collagen-based bioinks and suggest future research objectives.

Application and progress of 3D printed biomaterials in osteoporosis

Osteoporosis results from a disruption in skeletal homeostasis caused by an imbalance between bone resorption and bone formation. Conventional treatments, such as pharmaceutical drugs and hormone replacement therapy, often yield suboptimal results and are frequently associated with side effects. Recently, biomaterial-based approaches have gained attention as promising alternatives for managing osteoporosis. This review summarizes the current advancements in 3D-printed biomaterials designed for osteoporosis treatment. The benefits of biomaterial-based approaches compared to traditional systemic drug therapies are discussed. These 3D-printed materials can be broadly categorized based on their functionalities, including promoting osteogenesis, reducing inflammation, exhibiting antioxidant properties, and inhibiting osteoclast activity. 3D printing has the advantages of speed, precision, personalization, etc. It is able to satisfy the requirements of irregular geometry, differentiated composition, and multilayered structure of articular osteochondral scaffolds with boundary layer structure. The limitations of existing biomaterials are critically analyzed and future directions for biomaterial-based therapies are considered.

Characteristics and food applications of aquatic collagen and its derivatives: A review

Collagen and its hydrolysates have high bioavailability, good biocompatibility, biodegradability, and biological activity which has meant that they have been widely used in food, medicine, cosmetics, and other industries. Although the properties and applications of collagen have been reviewed recently, few studies have focused on aquatic collagen. To provide readers with a deeper understanding of aquatic collagen, this review addresses the structure and properties of aquatic collagen and compares them with mammalian collagen, as well as the differences between collagen, gelatin, and collagen peptides. In contrast to mammalian collagen, aquatic collagen prevents zoonotic diseases, reduces environmental pollution, improves the utilization of aquatic resources, and facilitates the extraction and separation of active oligopeptides. Additionally, methods for screening functional peptides using in vitro digestion have been introduced. Finally, the review focuses on the applications of collagen and its derivatives in food preservation (packaging films, coatings, additives, and antifreeze peptides), drug delivery (microcapsules, emulsions, nanoparticles, and hydrogels), nutrition, and healthcare.

Functional outcome of cell seeded tracheal scaffold after mechanical stress in vitro

Tracheal tissue engineering is still facing major challenges: realization of efficient vascularization and mechanical properties comparable to native trachea need to be achieved. In this study, we present a strategy for the manufacturing of a construct for tracheal tissue engineering by conditioning through cell seeding followed by mechanical stimulation in vitro. Scaffolds derived from porcine trachea decellularized with supercritical carbon dioxide were seeded with stem cells of different tissue sources and cultured in a bioreactor for 21 days under mechanical stimulation. Enhanced chondrogenic development was demonstrated, with improved sulphated glycosaminoglycan secretion and cellular alignment which resulted in mechanical properties resembling native trachea. This method may provide a useful addition to tracheal tissue engineering strategies aimed at optimizing cartilage formation.

Deproteinized Bovine Bone Mineral With Collagen for Anterior Maxillary Ridge Augmentation: A Retrospective Cohort Study

OBJECTIVES

This study aimed to assess the effects of deproteinized bovine bone mineral with collagen (DBBMC) combined with deproteinized bovine bone mineral (DBBM) on facial alveolar bone augmentation in the anterior maxillary region.

MATERIALS AND METHODS

Patients receiving dental implant placement with simultaneous lateral bone augmentation using DBBM (control group) or DBBMC combined with DBBM (test group) were included in the study. The radiographic assessment of facial alveolar bone, such as facial horizontal bone thickness (FHBT), facial vertical bone level (FVBL), and square of facial bone (SFB), was taken by cone beam computed tomography (CBCT). Generalized estimated equation (GEE) was performed to identify influencing factors associated with the contraction in square of facial bone (SFBC).

RESULTS

A total of 164 implants from 164 patients were included in this study. After 6 months post-surgery, the SFBC and the alterations of FHBT and FVBL in the test group were significantly higher than those in the control group (p < 0.05). After 1-2 years after restorations, the SFBC and the alterations of FHBT and FVBL in the test group were significantly lower than those in the control group (p < 0.05). Spearman correlation analysis demonstrated a positive correlation between the alterations of FVBL and FHBT at the implant platform level in the test group (rs = 0.322, p = 0.001; rs = 0.349, p = 0.002). Implant timing of early loading (p = 0.014) and the implant site of the central incisor (p = 0.040) were significantly associated with the SFBC.

CONCLUSIONS

The applications of DBBMC combined with DBBM achieved better facial alveolar bone augmentation in the anterior maxillary region, especially in early implant placement.