Biomedical and industrial applications of collagen

Novel Modification of Collagen: Realizing Desired Water Solubility and Thermostability in a Conflict-Free Way

Because of poor water solubility and low thermostability, the application of collagen is limited seriously in fields such as injectable biomaterials and cosmetics. In order to overcome the two drawbacks simultaneously, a novel bifunctional modifier based on the esterification of polyacrylic acid (PAA) with N-hydroxysuccinimide (NHS) was prepared. The esterification degree of PAA-NHS esters was increased upon increasing the NHS dose, which was confirmed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance spectrascopy. FTIR results indicated that the triple helix of the modified collagens remained integrated, whereas the molecular weight became larger, as reflected by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern. The modified collagens displayed excellent water solubility under neutral condition, owing to lower isoelectric point (3.1-4.3) than that of native collagen (7.1). Meanwhile, denaturation temperatures of the modified collagens were increased by 4.8-5.9 °C after modification. The modified collagen displayed hierarchical microstructures, as reflected by field-emission scanning electron microscopy, while atomic force microscopy further revealed a "fishing net-like" network in the nanoscale, reflecting a unique aggregation behavior of collagen macromolecules after modification. As a whole, the PAA-NHS ester as a bifunctional modifier endowed collagen with desired water solubility and thermostability in a conflict-free manner, which was beneficial to the process and application of the water-soluble collagen.

Elicited ROS Scavenging Activity, Photoprotective, and Wound-Healing Properties of Collagen-Derived Peptides from the Marine Sponge Chondrosia reniformis

Recently, the bioactive properties of marine collagen and marine collagen hydrolysates have been demonstrated. Although there is some literature assessing the general chemical features and biocompatibility of collagen extracts from marine sponges, no data are available on the biological effects of sponge collagen hydrolysates for biomedical and/or cosmetic purposes. Here, we studied the in vitro toxicity, antioxidant, wound-healing, and photoprotective properties of four HPLC-purified fractions of trypsin-digested collagen extracts-marine collagen hydrolysates (MCHs)-from the marine sponge C. reniformis. The results showed that the four MCHs have no degree of toxicity on the cell lines analyzed; conversely, they were able to stimulate cell growth. They showed a significant antioxidant activity both in cell-free assays as well as in H₂O₂ or quartz-stimulated macrophages, going from 23% to 60% of reactive oxygen species (ROS) scavenging activity for the four MCHs. Finally, an in vitro wound-healing test was performed with fibroblasts and keratinocytes, and the survival of both cells was evaluated after UV radiation. In both experiments, MCHs showed significant results, increasing the proliferation speed and protecting from UV-induced cell death. Overall, these data open the way to the use of C. reniformis MCHs in drug and cosmetic formulations for damaged or photoaged skin repair.

Collagen: A review on its sources and potential cosmetic applications

Collagen is a fibrillar protein that conforms the conjunctive and connective tissues in the human body, essentially skin, joints, and bones. This molecule is one of the most abundant in many of the living organisms due to its connective role in biological structures. Due to its abundance, strength and its directly proportional relation with skin aging, collagen has gained great interest in the cosmetic industry. It has been established that the collagen fibers are damaged with the pass of time, losing thickness and strength which has been strongly related with skin aging phenomena [Colágeno para todo. 60 y más. 2016. http://www.revista60ymas.es/InterPresent1/groups/revistas/documents/binario/ses330informe.pdf.]. As a solution, the cosmetic industry incorporated collagen as an ingredient of different treatments to enhance the user youth and well-being, and some common presentations are creams, nutritional supplement for bone and cartilage regeneration, vascular and cardiac reconstruction, skin replacement, and augmentation of soft skin among others [J App Pharm Sci. 2015;5:123-127]. Nowadays, the biomolecule can be obtained by extraction from natural sources such as plants and animals or by recombinant protein production systems including yeast, bacteria, mammalian cells, insects or plants, or artificial fibrils that mimic collagen characteristics like the artificial polymer commercially named as KOD. Because of its increased use, its market size is valued over USD 6.63 billion by 2025 [Collagen Market By Source (Bovine, Porcine, Poultry, Marine), Product (Gelatin, Hydrolyzed Collagen), Application (Food & Beverages, Healthcare, Cosmetics), By Region, And Segment Forecasts, 2014 - 2025. Grand View Research. http://www.grandviewresearch.com/industry-analysis/collagen-market. Published 2017.]. Nevertheless, there has been little effort on identifying which collagen types are the most suitable for cosmetic purposes, for which the present review will try to enlighten in a general scope this unattended matter.

Novel 3D coaxial flow-focusing nozzle device for the production of monodispersed collagen microspheres

We have developed a 3D coaxial flow-focusing nozzle device for the mass production of monodispersed collagen microspheres and chemically crosslinked them using EDC (1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide) and N-hydroxysuccinimide (NHS). The size of the microspheres was varied between 200 μm and 600 μm by adjusting the ratio of the flow rates of the dispersed and continuous phases. MDA231-GFP cells were attached to the surface of these particles and their viability was investigated. Because they are comprised of a natural biomaterial, these collagen microspheres will have numerous applications, including bone regeneration scaffolds for tissue engineering and analyses of cancer cell interactions in a 3D environment.

Collagen from the Marine Sponges Axinella cannabina and Suberites carnosus: Isolation and Morphological, Biochemical, and Biophysical Characterization

In search of alternative and safer sources of collagen for biomedical applications, the marine demosponges Axinella cannabina and Suberites carnosus, collected from the Aegean and the Ionian Seas, respectively, were comparatively studied for their insoluble collagen, intercellular collagen, and spongin-like collagen content. The isolated collagenous materials were morphologically, physicochemically, and biophysically characterized. Using scanning electron microscopy and transmission electron microscopy the fibrous morphology of the isolated collagens was confirmed, whereas the amino acid analysis, in conjunction with infrared spectroscopy studies, verified the characteristic for the collagen amino acid profile and its secondary structure. Furthermore, the isoelectric point and thermal behavior were determined by titration and differential scanning calorimetry, in combination with circular dichroism spectroscopic studies, respectively.

The Bright Side of Gelatinous Blooms: Nutraceutical Value and Antioxidant Properties of Three Mediterranean Jellyfish (Scyphozoa)

Jellyfish are recorded with increasing frequency and magnitude in many coastal areas and several species display biological features comparable to the most popular Asiatic edible jellyfish. The biochemical and antioxidant properties of wild gelatinous biomasses, in terms of nutritional and nutraceutical values, are still largely unexplored. In this paper, three of the most abundant and commonly recorded jellyfish species (Aurelia sp.1, Cotylorhiza tuberculata and Rhizostoma pulmo) in the Mediterranean Sea were subject to investigation. A sequential enzymatic hydrolysis of jellyfish proteins was set up by pepsin and collagenase treatments of jellyfish samples after aqueous or hydroalcoholic protein extraction. The content and composition of proteins, amino acids, phenolics, and fatty acids of the three species were recorded and compared. Protein content (mainly represented by collagen) up to 40% of jellyfish dry weight were found in two of the three jellyfish species (C. tuberculata and R. pulmo), whereas the presence of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) was significantly higher in the zooxanthellate jellyfish C. tuberculata only. Remarkable antioxidant ability was also recorded from both proteinaceous and non proteinaceous extracts and the hydrolyzed protein fractions in all the three species. The abundance of collagen, peptides and other bioactive molecules make these Mediterranean gelatinous biomasses a largely untapped source of natural compounds of nutraceutical, cosmeceutical and pharmacological interest.

Engineering a vascularized collagen-β-tricalcium phosphate graft using an electrochemical approach

Vascularization of three-dimensional large synthetic grafts for tissue regeneration remains a significant challenge. Here we demonstrate an electrochemical approach, named the cell electrochemical detachment (CED) technique, to form an integral endothelium and use it to prevascularize a collagen-β-tricalcium phosphate (β-TCP) graft. The CED technique electrochemically detached an integral endothelium from a gold-coated glass rod to a collagen-infiltrated, channeled, macroporous β-TCP scaffold, forming an endothelium-lined microchannel containing graft upon removal of the rod. The in vitro results from static and perfusion culture showed that the endothelium robustly emanated microvascular sprouting and prevascularized the entire collagen/β-TCP integrated graft. The in vivo subcutaneous implantation studies showed that the prevascularized collagen/β-TCP grafts established blood flow originating from the endothelium-lined microchannel within a week, and the blood flow covered more areas in the graft over time. In addition, many blood vessels invaded the prevascularized collagen/β-TCP graft and the in vitro preformed microvascular networks anastomosed with the host vasculature, while collagen alone without the support of rigid ceramic scaffold showed less blood vessel invasion and anastomosis. These results suggest a promising strategy for effectively vascularizing large tissue-engineered grafts by integrating multiple hydrogel-based CED-engineered endothelium-lined microchannels into a rigid channeled macroporous scaffold.

Marine origin collagens and its potential applications

Collagens are the most abundant high molecular weight proteins in both invertebrate and vertebrate organisms, including mammals, and possess mainly a structural role, existing different types according with their specific organization in distinct tissues. From this, they have been elected as one of the key biological materials in tissue regeneration approaches. Also, industry is constantly searching for new natural sources of collagen and upgraded methodologies for their production. The most common sources are from bovine and porcine origin, but other ways are making their route, such as recombinant production, but also extraction from marine organisms like fish. Different organisms have been proposed and explored for collagen extraction, allowing the sustainable production of different types of collagens, with properties depending on the kind of organism (and their natural environment) and extraction methodology. Such variety of collagen properties has been further investigated in different ways to render a wide range of applications. The present review aims to shed some light on the contribution of marine collagens for the scientific and technological development of this sector, stressing the opportunities and challenges that they are and most probably will be facing to assume a role as an alternative source for industrial exploitation.

Orientation distribution of highly oriented type I collagen deposited on flat samples with different geometries

The structural arrangement of type I collagen in vivo is critical for the normal functioning of tissues, such as bone, cornea, tendons, and blood vessels. At present, there are no established low-cost techniques for fabricating aligned collagen structures for applications in regenerative medicine. Here, we report on a straightforward approach to fabricate collagen films, with defined orientation distributions of collagen fibrillar aggregates within a matrix of oriented collagen molecules on flat sample surfaces. Langmuir-Blodgett (LB) technology was used to deposit thin films of oriented type I collagen onto flat substrates exhibiting various shapes. By varying the shapes of the substrates (e.g., rectangles, squares, circles, parallelograms, and various shaped triangles) as well as their sizes, a systematic study on collagen alignment patterns was conducted. It was found that the orientation and the orientation distribution of collagen along these various shaped substrates are directly depending on the geometry of the substrate and the dipping direction of that sample with respect to the collagen/water subphase. An important factor in tissue engineering is the stability, durability, and endurance of the constructed artificial tissue and thus its functioning in regenerative medicine applications. By testing these criteria, we found that the coated films and their alignments were stable for at least three months under different conditions and, moreover, that these films can withstand temperatures of up to 60 °C for a short time. Therefore, these constructs may have widespread applicability in the engineering of collagen-rich tissues.

Collagen for bone tissue regeneration

In the last decades, increased knowledge about the organization, structure and properties of collagen (particularly concerning interactions between cells and collagen-based materials) has inspired scientists and engineers to design innovative collagen-based biomaterials and to develop novel tissue-engineering products. The design of resorbable collagen-based medical implants requires understanding the tissue/organ anatomy and biological function as well as the role of collagen's physicochemical properties and structure in tissue/organ regeneration. Bone is a complex tissue that plays a critical role in diverse metabolic processes mediated by calcium delivery as well as in hematopoiesis whilst maintaining skeleton strength. A wide variety of collagen-based scaffolds have been proposed for different tissue engineering applications. These scaffolds are designed to promote a biological response, such as cell interaction, and to work as artificial biomimetic extracellular matrices that guide tissue regeneration. This paper critically reviews the current understanding of the complex hierarchical structure and properties of native collagen molecules, and describes the scientific challenge of manufacturing collagen-based materials with suitable properties and shapes for specific biomedical applications, with special emphasis on bone tissue engineering. The analysis of the state of the art in the field reveals the presence of innovative techniques for scaffold and material manufacturing that are currently opening the way to the preparation of biomimetic substrates that modulate cell interaction for improved substitution, restoration, retention or enhancement of bone tissue function.

Controlled deposition of highly oriented type I collagen mimicking in vivo collagen structures

The structural arrangement of type I collagen in vivo is critical for the normal functioning of tissues, such as bone, cornea, and blood vessels. At present, there are no low-cost techniques for fabricating aligned collagen structures for applications in regenerative medicine. Here, we report a straightforward approach to fabricate collagen films, with defined orientation of collagen fibrillar aggregates within a matrix of oriented collagen molecules. Langmuir-Blodgett (LB) technology was used to deposit thin films of oriented type I collagen onto substrates. It was found that collagen does not behave like classical LB materials, such as amphiphilic hydrocarbon acids or lipids. The thickness of the deposited collagen films and the area-pressure isotherms were found to depend on the amount of material spread. In addition, no film collapse was detected and the deposited LB films were thicker than the theoretical dimension of a collagen monolayer (1.5 nm) formed by triple helical collagen molecules. Individual LB films with thicknesses of up to 20 nm were obtained, and multiple depositions yielded overall film thicknesses of up to 100 nm. Films consisted of a matrix of collagen molecules containing thicker fibrillar aggregates of collagen (micrometers in length). These fibrillar aggregates were built up of shorter unit molecules forming "spun thread" structures, some of which exhibited a zigzag pattern. In addition to aligning collagen unidirectionally (similar for example to tendon), we performed a two-step deposition procedure, in which the substrate was turned 90 degrees between two consecutive collagen deposition steps. The resulting films showed orthogonally aligned collagen layers, mimicking the structure of cornea. Thus, this technique permits control of the thickness of individual layers, the orientation of successive layers, and the number of layers within the construct. Therefore, it may have widespread applicability for the engineering of collagen-rich tissues.

Extraction and characterization of collagen with or without telopeptides from chicken skin

Poultry by-products are not often processed into high-value products. Rather than being transformed into meal for animal feed, a large quantity of chicken skin could be used to produce collagen, which is valued for its unique functional properties. The purpose of this research project was to extract and characterize collagen from chicken skin. Skins were first ground and then were heated to 40 or 60 degrees C to extract the fat. After mechanical separation, the collagen contained in the resulting solid phase was extracted with pepsin or ethylene diamine. Types I and III collagen were then isolated and characterized by SDS PAGE, antigen labeling, determination of tyrosine residues, and transmission electron microscopy. The total collagen content of the skin was recovered from the solid phase following heat treatment at 40 degrees C. Extraction yields varied with the solubilization process: 38.9% of the collagen content in the solid phase was extracted with pepsin and 25.1% with ethylene diamine. Ratios of type I to type III collagen fractionated using NaCl were 74.4:19.8% with pepsin and 62.4:31.7% with ethylene diamine. Characterization tests further revealed the presence of telopeptides solely on ethylene diamine-solubilized collagen. Chicken skin thus appears to be a good alternative source of high-quality collagen.