Shaping collagen for engineering hard tissues: Towards a printomics approach

Waste-to-resource: Extraction and transformation of aquatic biomaterials for regenerative medicine

The fisheries and aquaculture industry are known for generating substantial waste or by-products, often underutilized, or relegated to low-value purposes. However, this overlooked segment harbors a rich repository of valuable bioactive materials of which have a broad-spectrum of high-value applications. As the blue economy gains momentum and fisheries expand, sustainable exploitation of these aquatic resources is increasingly prioritized. In this review, we present a comprehensive overview of technology-enabled methods for extracting and transforming aquatic waste into valuable biomaterials and their recent advances in regenerative medicine applications, focusing on marine collagen, chitin/chitosan, calcium phosphate and bioactive-peptides. We discuss the inherent bioactive qualities of these "waste-to-resource" aquatic biomaterials and identify opportunities for their use in regenerative medicine to advance healthcare while achieving the Sustainable Development Goals.

Applications and interventions of polymers and nanomaterials in alveolar bone regeneration and tooth dentistry

Inflammatory diseases exert a significant influence on the periodontium, serving as a primary contributor to the development of periodontitis. The advancement of periodontitis, characterized by manifestations, such as gingival recession, increased periodontal pocket depth and resorption across the alveolar bone, cementum and periodontal ligaments, poses a significant risk of dental detachment. Untreated or delayed treatment further worsens these deleterious outcomes. This emphasizes the critical importance of timely and effective interventions in reducing the consequences associated with periodontitis. Addressing these challenges requires to focus on the fabrication of bioactive materials, particularly scaffolds, as pivotal elements in tissue engineering processes aimed at alveolar bone regeneration. The incorporation of natural polymers, particularly their amalgamation with clays and clay minerals, such as montmorillonite and LAPONITE®, has been identified as a prospective pathway for advancing biomaterials in the realm of dentistry. This amalgamation holds significant potential for the production of biomaterials with enhanced properties, underscoring its relevance and applicability in dental research. This review paper explores the current advancements in natural polymer-based biomaterials employed in various dental applications, including oral caries, regenerative medicine and alveolar bone regeneration. The principal aim of this investigation is to briefly compile and present the existing knowledge while updating information on the utilization of natural polymers in the formulation of biomaterials. Additionally, the paper aims to elucidate their applications within contemporary research trends and developments in the field of odontology. This article extensively delves into pertinent research to assess the progress of nanotechnology in the context of tissue regeneration and the treatment of oral diseases.

Comprehensive review on collagen extraction from food by-products and waste as a value-added material

The consumption of animal products has witnessed a significant increase over the years, leading to a growing need for industries to adopt strict waste control measures to mitigate environmental impacts. The disposal of animal waste in landfill can result in diverse and potentially hazardous decomposition by-products. Animal by-products, derived from meat, poultry, seafood and fish industries, offer a substantial raw material source for collagen and gelatin production due to their high protein content. Collagen, being a major protein component of animal tissues, represents an abundant resource that finds application in various chemical and material industries. The demand for collagen-based products continues to grow, yet the availability of primary material remains limited and insufficient to meet projected needs. Consequently, repurposing waste materials that contain collagen provides an opportunity to meet this need while at the same time minimizing the amount of waste that is dumped. This review examines the potential to extract value from the collagen content present in animal-derived waste and by-products. It provides a systematic evaluation of different species groups and discusses various approaches for processing and fabricating repurposed collagen. This review specifically focuses on collagen-based research, encompassing an examination of its physical and chemical properties, as well as the potential for chemical modifications. We have detailed how the research and knowledge built on collagen structure and function will drive the new initiatives that will lead to the development of new products and opportunities in the future. Additionally, it highlights emerging approaches for extracting high-quality protein from waste and discusses efforts to fabricate collagen-based materials leading to the development of new and original products within the chemical, biomedical and physical science-based industries.

Recombinant collagen for the repair of skin wounds and photo-aging damage

The skin, being the body's primary defense mechanism, is susceptible to various injuries such as epidermal wounds, natural aging, and ultraviolet-induced damage. As a result, there is growing interest in researching skin repair methods. Traditional animal-derived collagen, widely available on the market, poses risks due to its immunogenicity and potential for viral contamination. In contrast, recombinant collagen sourced from human genes offers a safer alternative. To investigate the potential of human recombinant collagen in skin repair, our research team applied two types, type I human collagen (Col I) and CF-1552(I), to two different skin injury models: a wound-healing model and a photo-aging model. Our findings indicate that both Col I and CF-1552(I) effectively enhance wound healing and repair skin damaged by ultraviolet exposure. Notably, CF-1552(I) showed effects comparable to Col I in promoting cell proliferation in the wound-healing model and increasing malondialdehyde content in the photo-aging model, suggesting that CF-1552(I) may offer greater potential for skin repair compared to the larger Col I molecule.

Chitosan-based injectable hydrogel with multifunction for wound healing: A critical review

Different types of clinical wounds are difficult to treat while infected by bacteria. Wound repair involves multiple cellular and molecular interactions, which is a complicated process. However, wound repair often suffers from abnormal cellular functions or pathways that result in unavoidable side effects, so there is an urgent need for a material that can heal wounds quickly and with few side effects. Based on these needs, hydrogels with injectable properties have been confirmed to be able to undergo self-healing, which provides favorable conditions for wound healing. Notably, as a biopolymer with excellent easy-to-modify properties from a wide range of natural sources, chitosan can be used to prepare injectable hydrogel with multifunction for wound healing because of its outstanding flowability and injectability. Especially, chitosan-based hydrogels with marked biocompatibility, non-toxicity, and bio-adhesion properties are ideal for facilitating wound healing. In this review, the characteristics and healing mechanisms of different wounds are briefly summarized. In addition, the preparation and characterization of injectable chitosan hydrogels in recent years are classified. Additionally, the bioactive properties of this type of hydrogel in vitro and in vivo are demonstrated, and future trend in wound healing is prospected.

Enhancing the Repair of Substantial Volumetric Muscle Loss by Creating Different Levels of Blood Vessel Networks Using Pre-Vascularized Nerve Hydrogel Implants

Volumetric muscle loss (VML), a severe muscle tissue loss from trauma or surgery, results in scarring, limited regeneration, and significant fibrosis, leading to lasting reductions in muscle mass and function. A promising approach for VML recovery involves restoring vascular and neural networks at the injury site, a process not extensively studied yet. Collagen hydrogels have been investigated as scaffolds for blood vessel formation due to their biocompatibility, but reconstructing blood vessels and guiding innervation at the injury site is still difficult. In this study, collagen hydrogels with varied densities of vessel-forming cells are implanted subcutaneously in mice, generating pre-vascularized hydrogels with diverse vessel densities (0-145 numbers/mm2) within a week. These hydrogels, after being transplanted into muscle injury sites, are assessed for muscle repair capabilities. Results showed that hydrogels with high microvessel densities, filling the wound area, effectively reconnected with host vasculature and neural networks, promoting neovascularization and muscle integration, and addressing about 63% of the VML.

IPN based hydrogels for in-vivo wound dressings; catalytic wound healing dynamics and isothermal adsorption models

Interpenetrating network (IPN) methacrylated chitosan or methacrylated flaxseed gum based hydrogels have been utilized to make outstanding in-vivo wound dressings. The photopolymerization process was accomplished in presence of Eosin-Y photoinitiator with average exposure time of 13-14 s for gelation. Spectroscopic structural investigations of 1H NMR. ATR-FTIR, TGA, and AFM techniques were used. In-vitro hemolysis test provided evidence of no cytotoxicity in both hydrogels observed. The in-vivo wound dressings were monitored for five mice coated with each hydrogel and another uncoated five mice for control (self-healing). All measurements were performed in quintuplicate (n = 5) and expressed as mean ± SD values. In wound healing dynamics, our data confirmed that wound healing pass through two stages; hemostasis and inflammation for stage 1, and proliferation and remodeling for stage 2. It also provided evidence of 1st order kinetics with descending rate of healing. Consequently, catalytic role of hydrogels in wound healing was checked via half-life (δ) and negative change of activation energy values (ΔEa). Various isothermal adsorption models demonstrated spontaneous and high binding affinities of hydrogels. It also confirmed the two-stage healing process in presence of hydrogels. Conclusively, the outstanding properties of the two hydrogels suggest their potential applications in treating venous ulcers and diabetic wound healing dressings.

An Injectable silk-based hydrogel as a novel biomineralization seedbed for critical-sized bone defect regeneration

The healing process of critical-sized bone defects urges for a suitable biomineralization environment. However, the unsatisfying repair outcome usually results from a disturbed intricate milieu and the lack of in situ mineralization resources. In this work, we have developed a composite hydrogel that mimics the natural bone healing processes and serves as a seedbed for bone regeneration. The oxidized silk fibroin and fibrin are incorporated as rigid geogrids, and amorphous calcium phosphate (ACP) and platelet-rich plasma serve as the fertilizers and loam, respectively. Encouragingly, the seedbed hydrogel demonstrates excellent mechanical and biomineralization properties as a stable scaffold and promotes vascularized bone regeneration in vivo. Additionally, the seedbed serves a succinate-like function via the PI3K-Akt signaling pathway and subsequently orchestrates the mitochondrial calcium uptake, further converting the exogenous ACP into endogenous ACP. Additionally, the seedbed hydrogel realizes the succession of calcium resources and promotes the evolution of the biotemplate from fibrin to collagen. Therefore, our work has established a novel silk-based hydrogel that functions as an in-situ biomineralization seedbed, providing a new insight for critical-sized bone defect regeneration.

Degradable biomedical elastomers: paving the future of tissue repair and regenerative medicine

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering.

An engineered lamellar bone mimicking full-scale hierarchical architecture for bone regeneration

Lamellar bone, compactly and ingeniously organized in the hierarchical pattern with 6 ordered scales, is the structural motif of mature bone. Each hierarchical scale exerts an essential role in determining physiological behavior and osteogenic bioactivity of bone. Engineering lamellar bone with full-scale hierarchy remains a longstanding challenge. Herein, using bioskiving and mineralization, we attempt to engineer compact constructs resembling full-scale hierarchy of lamellar bone. Through systematically investigating the effect of mineralization on physicochemical properties and bioactivities of multi-sheeted collagen matrix fabricated by bioskiving, the hierarchical mimicry and hierarchy-property relationship are elucidated. With prolongation of mineralization, hierarchical mimicry and osteogenic bioactivity of constructs are performed in a bidirectional manner, i.e. first rising and then descending, which is supposed to be related with transformation of mineralization mechanism from nonclassical to classical crystallization. Construct mineralized 9 days can accurately mimic each hierarchical scale and efficiently promote osteogenesis. Bioinformatic analysis further reveals that this construct potently activates integrin α5-PI3K/AKT signaling pathway through mechanical and biophysical cues, and thereby repairing critical-sized bone defect. The present study provides a bioinspired strategy for completely resembling complex hierarchy of compact mineralized tissue, and offers a critical research model for in-depth studying the structure-function relationship of bone.

Construction of 3D bioprinting of HAP/collagen scaffold in gelation bath for bone tissue engineering

Reconstruction of bone defects remains a clinical challenge, and 3D bioprinting is a fabrication technology to treat it via tissue engineering. Collagen is currently the most popular cell scaffold for tissue engineering; however, a shortage of printability and low mechanical strength limited its application via 3D bioprinting. In the study, aiding with a gelatin support bath, a collagen-based scaffold was fabricated via 3D printing, where hydroxyapatite (HAP) and bone marrow mesenchymal stem cells (BMSCs) were added to mimic the composition of bone. The results showed that the blend of HAP and collagen showed suitable rheological performance for 3D extrusion printing and enhanced the composite scaffold's strength. The gelatin support bath could effectively support the HAP/collagen scaffold's dimension with designed patterns at room temperature. BMSCs in/on the scaffold kept living and proliferating, and there was a high alkaline phosphate expression. The printed collagen-based scaffold with biocompatibility, mechanical properties and bioactivity provides a new way for bone tissue engineering via 3D bioprinting.

Effect and mechanism of signal peptide and maltose on recombinant type III collagen production in Pichia pastoris

Recombinant type III collagen plays an important role in cosmetics, wound healing, and tissue engineering. Thus, increasing its production is necessary. After an initial increase in output by modifying the signal peptide, we showed that adding 1% maltose directly to the medium increased the yield and reduced the degradation of recombinant type III collagen. We initially verified that Pichia pastoris GS115 can metabolize and utilize maltose. Interestingly, maltose metabolism-associated proteins in Pichia pastoris GS115 have not yet been identified. RNA sequencing and transmission electron microscopy were performed to clarify the specific mechanism of maltose influence. The results showed that maltose significantly improved the metabolism of methanol, thiamine, riboflavin, arginine, and proline. After adding maltose, the cell microstructures tended more toward the normal. Adding maltose also contributed to yeast homeostasis and methanol tolerance. Finally, adding maltose resulted in the downregulation of aspartic protease YPS1 and a decrease in yeast mortality, thereby slowing down recombinant type III collagen degradation. KEY POINTS: • Co-feeding of maltose improves recombinant type III collagen production. • Maltose incorporation enhances methanol metabolism and antioxidant capacity. • Maltose addition contributes to Pichia pastoris GS115 homeostasis.

Improving Effects of Peripheral Nerve Decompression Microsurgery of Lower Limbs in Patients with Diabetic Peripheral Neuropathy

Background: Peripheral nerve decompression microsurgery can relieve nerve entrapment and improve the symptoms of DPN. However, postoperative tissue adhesion will produce new pressure on the nerves, affecting the surgical efficacy. In this study, a nerve conduit was used in the peripheral nerve decompression microsurgery to prevent postoperative adhesions, and the role of the nerve conduit in surgical nerve decompression was explored. Methods: A total of 69 patients with DPN were recruited and randomly divided into three groups: the nerve conduit group, conventional surgery group, and control group. Two weeks before surgery and 6 months after surgery, patients in each group were clinically tested using the visual analog scale (VAS) score, neurophysiological test, Toronto clinical scoring system (TCSS) score, and two-point discrimination (2-PD) test. Results: The patients’ symptoms in the nerve conduit group were relieved to varying degrees, and the relief rate reached 90.9%; the treatment efficacy was higher than that in the other groups. The postoperative nerve conduction velocity (NCV) in the two surgical groups was significantly higher than that before the surgery, and the difference between the nerve conduit group and the conventional surgery group was statistically significant (p < 0.05). For the 2-PD test, there was a statistically significant difference between the two surgical groups (p < 0.05). The TCSS score in the two surgical groups was significantly higher than that in the control group (p < 0.01). There was a significant difference in the TCSS scores between the nerve conduit group and the conventional surgery group (p < 0.05). Conclusions: The nerve conduit could further improve the efficacy of peripheral nerve decompression microsurgery in the treatment of DPN.

Accelerating bone regeneration using poly(lactic-co-glycolic acid)/hydroxyapatite scaffolds containing duck feet-derived collagen

Collagen, with low antigenicity and excellent cell adhesion, is a biomaterial mainly used for regenerating bone, cartilage, and skin, owing to its biocompatibility and biodegradability. Results from a previous study confirmed that a scaffold mixed with duck feet-derived collagen (DC) and Poly(lactic-co-glycolic acid) (PLGA) reduced inflammatory reaction and increased bone regeneration. To develop an optimal bone substitute we included hydroxyapatite (HAp), a key osteoconductive material, in a DC and PLGA mixture. We fabricated 0, 10, 20, 40, 60, and 80 wt% DC/PLGA/HAp scaffolds and studied their potential for bone tissue engineering. Characteristic analysis of the scaffold and seeding of rabbit bone marrow mesenchymal stem cells (rBMSCs) on the scaffold were conducted to investigate cell proliferation, osteogenic differentiation, and bone formation. We confirmed that increasing DC concentration not only improved the compressive strength of the DC/PLGA/HAp scaffold but also cell proliferation and osteogenic differentiation. It was found through comparison with previous studies that including HAp in the scaffold also promotes osteogenic differentiation. Our study thus shows through in vivo results that the 80 wt% DC/PLGA/HAp scaffold promotes bone mineralization and collagen deposition while reducing the inflammatory response. Hence, 80 wt% DC/PLGA/HAp has excellent potential as a biomaterial for bone regeneration applications.

Cutting Edge Aquatic-Based Collagens in Tissue Engineering

Aquatic-based collagens have attracted much interest due to their great potential application for biomedical sectors, including the tissue engineering sector, as a major component of the extracellular matrix in humans. Their physical and biochemical characteristics offer advantages over mammalian-based collagen; for example, they have excellent biocompatibility and biodegradability, are easy to extract, and pose a relatively low immunological risk to mammalian products. The utilization of aquatic-based collagen also has fewer religious restrictions and lower production costs. Aquatic-based collagen also creates high-added value and good environmental sustainability by aquatic waste utilization. Thus, this study aims to overview aquatic collagen's characteristics, extraction, and fabrication. It also highlights its potential application for tissue engineering and the regeneration of bone, cartilage, dental, skin, and vascular tissue. Moreover, this review highlights the recent research in aquatic collagen, future prospects, and challenges for it as an alternative biomaterial for tissue engineering and regenerative medicines.

Hydrogel: A Potential Material for Bone Tissue Engineering Repairing the Segmental Mandibular Defect

Free flap surgery is currently the only successful method used by surgeons to reconstruct critical-sized defects of the jaw, and is commonly used in patients who have had bony lesions excised due to oral cancer, trauma, infection or necrosis. However, donor site morbidity remains a significant flaw of this strategy. Various biomaterials have been under investigation in search of a suitable alternative for segmental mandibular defect reconstruction. Hydrogels are group of biomaterials that have shown their potential in various tissue engineering applications, including bone regeneration, both through in vitro and in vivo pre-clinical animal trials. This review discusses different types of hydrogels, their fabrication techniques, 3D printing, their potential for bone regeneration, outcomes, and the limitations of various hydrogels in preclinical models for bone tissue engineering. This review also proposes a modified technique utilizing the potential of hydrogels combined with scaffolds and cells for efficient reconstruction of mandibular segmental defects.

Bioprinting of hair follicle germs for hair regenerative medicine

Hair regenerative medicine is a promising approach to treat hair loss. The replication of in vivo tissue configurations and microenvironments, such as hair follicle germs, has been studied to prepare tissue grafts for hair regenerative medicine. However, such approaches should be scalable, because a single patient with alopecia requires thousands of tissue grafts. In this paper, we propose an approach for the scalable and automated preparation of highly hair-inductive tissue grafts using a bioprinter. Two collagen droplets (2 µL each) containing mesenchymal and epithelial cells were placed adjacent to each other to fabricate hair-follicle-germ-like grafts. During three days of culture, the pairs of microgel beads were spontaneously contracted by cell traction forces, whereas the two cell types remained separated, where the densities of the cells and collagen were enriched more than 10 times. This approach allowed us to fabricate submillimeter objects printed with millimeter-order accuracy, facilitating scalable and automated tissue graft preparation. Because of mesenchymal-epithelial interactions, hair microgels (HMGs, i.e., collagen- and cell-enriched microgels) efficiently regenerate hair follicles and shafts when transplanted into the back skin of mice. However, the generated hair shafts mostly remain under the skin. Therefore, we printed microgel beads onto surgical suture guides arrayed on a stage. The microgel beads were contracted along with the suture guides in culture prior to transplantation. The guide-inserted HMGs significantly improved hair-shaft sprouting through the skin, owing to the control of the orientation of the HMGs transplanted into the skin. This approach is a promising strategy to advance hair regenerative medicine. STATEMENT OF SIGNIFICANCE: This study proposes an approach for the scalable and automated preparation of highly hair-inductive grafts using a bioprinter. Two collagen droplets containing mesenchymal and epithelial cells were placed adjacently. Cell traction forces caused the pairs of microgel beads to spontaneously contract in culture. Because of mesenchymal-epithelial interactions, hair microgels (HMGs) efficiently regenerated hair follicles on the back skin of mice. However, the generated hair shafts remained mostly beneath the skin. Therefore, we printed microgel beads onto surgical suture guides arrayed on a stage. The guide-inserted HMGs significantly improved hair-shaft sprouting through the skin owing to the control of the orientation of the HMGs in the skin. This approach represents a promising strategy for advancing hair regenerative medicine.

Process optimization for extraction of avian eggshell membrane derived collagen for tissue engineering applications

The avian eggshell membranes’ composition depicts close resemblance with the extracellular matrix of the cells, and therefore being widely employed as potential biomaterials for tissue engineering applications. However, the optimization of process conditions for collagen extraction, the main constituent of eggshell membranes is still challenging. In the present study, extraction of collagen was performed by an enzymatic method optimized through the one-factor-at-a-time (OFAT) technique for three parameters viz. pepsin concentration, treatment time and pH. The process optimization resulted in the maximum yield of 56% collagen with 350 U/mg pepsin concentration at pH 3 treated for 9 days, not reported yet. The collagen extraction was confirmed by OD at 232 nm; and its viscoelasticity behaviour at pH 5. The physico–chemical characterization of extracted collagen with FESEM, ATR-FTIR, surface roughness analysis and contact angle measurement revealed the morphological and topological alteration during the collagen extraction. The process optimization and characterization of eggshell membrane derived collagen can aid in the significant biomaterials development for tissue regeneration.

Prevention of collagen hydrogel contraction using polydopamine-coating and alginate outer shell increases cell contractile force

Collagen is the most abundant protein in the extracellular matrix of mammals and has a great effect on various cell behaviors including adhesion, differentiation, and migration. However, it is difficult to utilize collagen gel as a physical scaffold in vitro because of its severe contraction. Decrease in the overall hydrogel volume induces changes in cell distribution, and mass transfer within the gel. Uncontrolled mechanical and physiological factors in the fibrous matrix result in uncontrolled cell behaviors in the surrounding cells. In this study, two strategies were used to minimize the contraction of collagen gel. A disk-shaped frame made of polydopamine-coated polydimethylsiloxane (PDMS) prevented horizontal contraction at the edge of the hydrogel. The sequentially cross-linked collagen gel with alginate outer shell (CA-shell) structure inhibited the vertical gel contraction. The combined method synergistically prevented the hydrogel from shrinkage in long-term 3D cell culture. We observed the shift in balance of differentiation from adipogenesis to osteogenesis in mesenchymal stem cells under the environment where gel contraction was prevented, and confirmed that this phenomenon is closely associated with the mechanotransduction based on Yes-associated protein (YAP) localization. Development of this contraction inhibition platform made it possible to investigate the influence of regulation of cellular microenvironments. The physical properties of the hydrogel fabricated in this study were similar to that of pure collagen gel but completely changed the cell behavior within the gel by inhibition of gel contraction. The platform can be used to broaden our understanding of the fundamental mechanism underlying cell-matrix interactions and reproduce extracellular matrix in vivo.

Variation in Hydrogel Formation and Network Structure for Telo-, Atelo- and Methacrylated Collagens

As the most abundant protein in the extracellular matrix, collagen has become widely studied in the fields of tissue engineering and regenerative medicine. Of the various collagen types, collagen type I is the most commonly utilised in laboratory studies. In tissues, collagen type I forms into fibrils that provide an extended fibrillar network. In tissue engineering and regenerative medicine, little emphasis has been placed on the nature of the network that is formed. Various factors could affect the network structure, including the method used to extract collagen from native tissue, since this may remove the telopeptides, and the nature and extent of any chemical modifications and crosslinking moieties. The structure of any fibril network affects cellular proliferation and differentiation, as well as the overall modulus of hydrogels. In this study, the network-forming properties of two distinct forms of collagen (telo- and atelo-collagen) and their methacrylated derivatives were compared. The presence of the telopeptides facilitated fibril formation in the unmodified samples, but this benefit was substantially reduced by subsequent methacrylation, leading to a loss in the native self-assembly potential. Furthermore, the impact of the methacrylation of the collagen, which enables rapid crosslinking and makes it suitable for use in 3D printing, was investigated. The crosslinking of the methacrylated samples (both telo- and atelo-) was seen to improve the fibril-like network compared to the non-crosslinked samples. This contrasted with the samples of methacrylated gelatin, which showed little, if any, fibrillar or ordered network structure, regardless of whether they were crosslinked.

Promoting mineralization at biological interfaces Ex vivo with novel amelotin-based bio-nano complexes

Conclusion

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AMTN/AMTN-Col functionalized HANP are potent mineral-promoting bio-nano complexes.

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AMTN/AMTN-Col coated HANP promote collagen mineralization.

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AMTN/AMTN-Col coated HANP enhance resin-dentin bond strength.

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AMTN/AMTN-Col coated HANP are potential candidates for clinical application.

Influence of Biomimetically Mineralized Collagen Scaffolds on Bone Cell Proliferation and Immune Activation

Collagen, as the main component of connective tissue, is frequently used in various tissue engineering applications. In this study, porous sponge-like collagen scaffolds were prepared by freeze-drying and were then mineralized in a simulated body fluid. The mechanical stability was similar in both types of scaffolds, but the mineralized scaffolds (MCS) contained significantly more calcium, magnesium and phosphorus than the unmineralized scaffolds (UCS). Although the MCS contained a lower percentage (~32.5%) of pores suitable for cell ingrowth (113–357 μm in diameter) than the UCS (~70%), the number of human-osteoblast-like MG-63 cells on days 1, 3 and 7 after seeding was higher on MCS than on UCS, and the cells penetrated deeper into the MCS. The cell growth in extracts prepared by eluting the scaffolds for 7 days in a cell culture medium was also markedly higher in the MCS extracts, as indicated by real-time monitoring in the sensory xCELLigence system for 7 days. From this point of view, MCS are more promising for bone tissue engineering than UCS. However, MCS evoked a more pronounced inflammatory response than UCS, as indicated by the production of tumor necrosis factor-alpha (TNF-α) in macrophage-like RAW 264.7 cells in cultures on these scaffolds.

The biological effect of recombinant humanized collagen on damaged skin induced by UV-photoaging: An in vivo study

The application of medical devices to repair skin damage is clinically accepted and natural polymer enjoys an important role in this field, such as collagen or hyaluronic acid, etc. However, the biosafety and efficacy of these implants are still challenged. In this study, a skin damage animal model was prepared by UV-photoaging and recombinant humanized type III collagen (rhCol III) was applied as a bioactive material to implant in vivo to study its biological effect, comparing with saline and uncrosslinked hyaluronic acid (HA). Animal skin conditions were non-invasively and dynamically monitored during the 8 weeks experiment. Histological observation, specific gene expression and other molecular biological methods were applied by the end of the animal experiment. The results indicated that rhCol III could alleviate the skin photoaging caused by UV radiation, including reduce the thickening of epidermis and dermis, increase the secretion of Collagen I (Col I) and Collagen III (Col III) and remodel of extracellular matrix (ECM). Although the cell-material interaction and mechanism need more investigation, the effect of rhCol III on damaged skin was discussed from influence on cells, reconstruction of ECM, and stimulus of small biological molecules based on current results. In conclusion, our findings provided rigorous biosafety information of rhCol III and approved its potential in skin repair and regeneration. Although enormous efforts still need to be made to achieve successful translation from bench to clinic, the recombinant humanized collagen showed superiorities from both safety and efficacy aspects.

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Investigated the biological effect of recombinant humanized collagen type III (rhCol III) in vivo.

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Provided the safety and efficacy evidence for rhCol III in skin damage repair.

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Preliminary mechanism discussion on the biological effect of rhCol III.

On the Path to Thermo-Stable Collagen: Culturing the Versatile Sponge Chondrosia reniformis

The collagen proteins family is sought-after in the pharmaceuticals, cosmetics, and food industries for various biotechnological applications. The most abundant sources of collagen are pigs and cows, but due to religious restrictions and possible disease transmission, they became less attractive. An alternative source can be found in marine invertebrates, specifically in sponges. Alas, two problems arise: (1). Growing sponges is complicated. (2). Sponge collagen has low heat tolerance, which can impose a problem for human biotechnological usage. To fill these gaps, we studied the collagen-abundant sponge Chondrosia reniformis. Two culture experiments were conducted: (1). A sea-based system examined the difference in growth rates of C. reniformis from different habitats, growing under natural seasonal conditions; (2). A land-based controlled system, which assessed the growth-rate of C. reniformis at different temperatures. The results reveal that C. reniformis from shallow habitats are growing larger and faster than individuals from colder, deeper habitats, and that the optimal temperature for C. reniformis growth is 25 °C. The results demonstrate that C. reniformis is highly fit for culture and can produce thermally stable collagen. Further research is needed to determine the best conditions for C. reniformis culture for collagen extract and other exciting materials for bioprospecting.