A Guide to Collagen Sources, Applications and Current Advancements

The increase in use of collagen products in almost every sector of utility has stipulated the rising demand for collagen. It is an essential fibrous glycoprotein, which is abundantly present in the extracellular matrix and connective tissues in many living organisms. Owing to its unique characteristics such as biocompatibility, bioavailability and weak antigenicity it has gained major interest in the food, pharmaceutical, cosmetic, biomedical and leather industries. The collagen-based composites possess an enhanced capacity to dissipate mechanical energy, strength and stiffness making it the most promising biomolecule for its multifaceted applications. Recently, synthetic biology platforms are getting wide attention for the production of non-native collagen alternatives to meet the rising demand for collagen worldwide. In the initial part, this review aims to explain different sources, structures, biosynthesis of collagen and its types followed by the emerging applications of collagen as a next-generation biomaterial in the later part. The article emphasises the synthesis of non-native collagen using novel expression systems like plant and algae in addition to bacteria and yeast with industrial consideration. In the conclusion section, challenges and opportunities of using synthetic biology tools are described.

3D-Printed Mucoadhesive Collagen Scaffolds as a Local Tetrahydrocurcumin Delivery System

Native collagen doughs were processed using a syringe-based extrusion 3D printer to obtain collagen scaffolds. Before processing, the rheological properties of the doughs were analyzed to determine the optimal 3D printing conditions. Samples showed a high shear-thinning behavior, reported beneficial in the 3D printing process. In addition, tetrahydrocurcumin (THC) was incorporated into the dough formulation and its effect on collagen structure, as well as the resulting scaffold’s suitability for wound healing applications, were assessed. The denaturation peak observed by differential scanning calorimetry (DSC), along with the images of the scaffolds’ surfaces assessed using scanning electron microscopy (SEM), showed that the fibrillar structure of collagen was maintained. These outcomes were correlated with X-ray diffraction (XRD) results, which showed an increase of the lateral packaging of collagen chains was observed in the samples with a THC content up to 4%, while a higher content of THC considerably decreased the structural order of collagen. Furthermore, physical interactions between collagen and THC molecules were observed using Fourier transform infrared (FTIR) spectroscopy. Additionally, all samples showed swelling and a controlled release of THC. These results along with the mucoadhesive properties of collagen suggested the potential of these THC–collagen scaffolds as sustained THC delivery systems.

Sequence-specific response of collagen-mimetic peptides to osmotic pressure

Native collagen molecules usually contract upon dehydration, but the details of their interaction with water are poorly understood. Previous molecular modeling studies indicated a spatially inhomogeneous response, with a combination of local axial expansion and contraction. Such sequence-dependent effects are difficult to study with native collagen. In this article, we use collagen-mimetic peptides (CMPs) to investigate the effect of osmotic pressure on several collagen-mimetic sequences. Synchrotron x-ray diffraction combined with molecular dynamics simulations shows that CMPs pack differently depending on osmotic pressure and exhibit changes in the helical rise per residue of individual molecules. Infrared spectroscopy reveals that osmotic pressure affects the stability of the triple helix through changes in triple helix-stabilizing hydrogen bonds. Surprisingly, CMPs with the canonical collagen sequence glycine–proline–hydroxyproline are found to elongate upon dehydration, while sequence modifications are able to reverse this tendency. This strongly suggests that the overall contraction of native collagen molecules is not programmed into the canonical sequence but is specific to local amino acids that substitute for proline or hydroxyproline along the protein chain. Collagen is an essential protein in mammalian extracellular tissues and a better understanding of its mechanical function is important both from a materials science and from a biomedical viewpoint. Recently, collagen has been shown to contract along the fibre direction when subjected to osmotic stress, a process that could play important roles in strengthening bone and in developing tissue tension during extracellular matrix development. The present work uses collagen-like short peptides to show that the canonical collagen sequence is not responsible for this contraction. The conclusion is that the collagen amino acid sequence must have evolved to include guest sequences within the canonical glycine-proline-hydroxyproline repeat that provide the observed contractility. Impact statement Collagen is an essential protein in mammalian extracellular tissues and a better understanding of its mechanical function is important both from a materials science and from a biomedical viewpoint. Recently, collagen has been shown to contract along the fibre direction when subjected to osmotic stress, a process that could play important roles in strengthening bone and in developing tissue tension during extracellular matrix development. The present work uses collagen-like short peptides to show that the canonical collagen sequence is not responsible for this contraction. The conclusion is that the collagen amino acid sequence must have evolved to include guest sequences within the canonical glycine-proline-hydroxyproline that provide the observed contractility. Graphic Abstract

Current Insights into Collagen Type I

Collagen type I (Col-I) is unique due to its high biocompatibility in human tissue. Despite its availability from various sources, Col-I naturally mimics the extracellular matrix (ECM) and generally makes up the larger protein component (90%) in vasculature, skin, tendon bone, and other tissue. The acceptable physicochemical properties of native Col-I further enhance the incorporation of Col-I in various fields, including pharmaceutical, cosmeceutical, regenerative medicine, and clinical. This review aims to discuss Col-I, covering the structure, various sources of availability, native collagen synthesis, current extraction methods, physicochemical characteristics, applications in various fields, and biomarkers. The review is intended to provide specific information on Col-I currently available, going back five years. This is expected to provide a helping hand for researchers who are concerned about any development on collagen-based products particularly for therapeutic fields.

POTENCY OF ORAL UN-DENATURED TYPE II COLLAGENIN THE TREATMENT OF OSTEOARTHRITIS, WITH SPECIFICAL RELATIONSHIP TO KNEE JOINT- A META-ANALYTIC REVIEW

Introduction: One of the chronic progressive diseases of the elderly is Osteoarthritis. There is a wide spectrum of Nutraceuticals, for Osteoarthritis, but there does not exist, a convincing literature based evidence, in support of their denitive and specic rationale of utility. We here in, aim to evaluate the evidence in literature hither to available, for establishing the potency and efcaciousness of the indigenous type II collagen variant. Methods: st st A schematic search was performed of Pub Med, Scopus and the Google Scholar, from dates (1 December 2009 to 1 December 2020), with the search terms: 'Osteoarthritis', 'Nutraceuticals', 'Oral Collagen', 'Glucosamine', 'Chondroitin Sulfate', 'Acetaminophen' and 'Native Collagen'. Articles containing the following were included in the study: Randomized Control Trial and Clinical Trial, Primary data, OA and Oral Collagen studies related to joint disease. Total number of patients studied, the number of patients who were treated by Native Collagen Type II variant, Denatured Collagen Type II variant, Glucosamine, Chondroitin Sulfate and Acetaminophen.A number of studies using various scoring systems were incorporated in our study. Finally, all the functional outcomes, according to the VAS and WOMAC scores, were cumulatively tabulated, and analyzed schematically and their results deduced. Results: Multiple researches have been executed, to elucidate upon the efcacy and the safety, of Oral Collagen of the type II variant, in the medicaments prescribed for OA, especially relating to the Knee joint. Oral Collagen is administered, either in a Denatured or an Undenatured form .The results indicate , that out of all the Nutraceuticals, Undenatured/Native collagen of the type II variant, proved to be by far the most safe and signicantly more efcacious, compared to other Nutraceuticals. Although all the suggested treatments reduced the WOMAC and the VAS scores, here in UC II, showed more efciency and sustenance of the pain reduction, in both the assessment scores, in comparison with other orally administrated Nutraceuticals. Conclusion: Our Meta-Analysis concludes that, Type II Undenatured Collagen, is a relatively safe and also signicantly more efcient, in improving the joint function, ROM and for the alleviation of bone joint pain, in OA knee (Genu OA) patients.

Translation of Collagen Ultrastructure to Biomaterial Fabrication for Material Independent but Highly Efficient Topographic Immunomodulation

<div>Supplement-free induction of cellular differentiation and polarization solely through the topography of materials is an auspicious strategy but has so far significantly lacked behind the efficiency and intensity of media-supplementation based protocols. For immune cells, low intensity effects were achieved on rhodent cells using standard technologically driven surface patterns and scaffold geometries, but no effects could be achieved for human immune cells. <br></div><p> </p> <p>Consistent with the idea that 3D structural motives in the extracellular matrix possess immunomodulatory capacity as part of the natural healing process, we found that human monocyte-derived macrophages show a strong M2a like pro-healing polarization when cultured on type I rat-tail collagen fibers (hereafter termed "collagen I") but not on collagen I films. <br></p><p>Therefore, we hypothesized that highly aligned nanofibrils also of synthetic polymers, if packed into larger bundles in 3D topographical similarity to native collagen I, would induce a localized macrophage polarization. <br></p> <p> </p> <p>For the automated fabrication of such bundles in a 3D printing manner, we pioneered the strategy of "Melt Electrofibrillation" by the integration of flow directed polymer phase separation into Melt Electrowriting and subsequent selective dissolution of the matrix polymer. This process yields nano-fiber bundles with a remarkable structural similarity to native collagen I fibers, particularly for medical grade polycaprolactone (PCL). </p> <p> </p> <p>These biomimetic fibrillar structures indeed induced a pronounced elongation of human monocyte-derived macrophages and unprecedentedly triggered their M2-like polarization as efficiently as IL-4 cytokine treatment.</p> <p> </p> <p>Our data evidence the biological importance of human macrophage-elongation on collagen fibers and pioneers a strategy to fabricate scaffolds that exploit this effect to drive macrophage polarization through precise and biomimetic material design. </p>

Translation of Collagen Ultrastructure to Biomaterial Fabrication for Material Independent but Highly Efficient Topographic Immunomodulation

<div>Supplement-free induction of cellular differentiation and polarization solely through the topography of materials is an auspicious strategy but has so far significantly lacked behind the efficiency and intensity of media-supplementation based protocols. For immune cells, low intensity effects were achieved on rhodent cells using standard technologically driven surface patterns and scaffold geometries, but no effects could be achieved for human immune cells. <br></div><p> </p> <p>Consistent with the idea that 3D structural motives in the extracellular matrix possess immunomodulatory capacity as part of the natural healing process, we found that human monocyte-derived macrophages show a strong M2a like pro-healing polarization when cultured on type I rat-tail collagen fibers (hereafter termed "collagen I") but not on collagen I films. <br></p><p>Therefore, we hypothesized that highly aligned nanofibrils also of synthetic polymers, if packed into larger bundles in 3D topographical similarity to native collagen I, would induce a localized macrophage polarization. <br></p> <p> </p> <p>For the automated fabrication of such bundles in a 3D printing manner, we pioneered the strategy of "Melt Electrofibrillation" by the integration of flow directed polymer phase separation into Melt Electrowriting and subsequent selective dissolution of the matrix polymer. This process yields nano-fiber bundles with a remarkable structural similarity to native collagen I fibers, particularly for medical grade polycaprolactone (PCL). </p> <p> </p> <p>These biomimetic fibrillar structures indeed induced a pronounced elongation of human monocyte-derived macrophages and unprecedentedly triggered their M2-like polarization as efficiently as IL-4 cytokine treatment.</p> <p> </p> <p>Our data evidence the biological importance of human macrophage-elongation on collagen fibers and pioneers a strategy to fabricate scaffolds that exploit this effect to drive macrophage polarization through precise and biomimetic material design. </p>

Extraction Methods, Characterization and Biomedical Applications of Collagen: a Review

It is difficult to develop a standard extraction method for all types of collagen from different tissues due to the extreme diversity of collagen types. Some procedures are based on the isolation of acid, pepsin, and enzymatic soluble collagen, showing certain advantages and disadvantages. Other methods were also optimized to partially purify collagen and extract it easier than the methods currently used. Indeed, this review describes some advantages and disadvantages of these isolation methods. Moreover, major biomedical applications of collagen were reported. Given the great importance of biocompatible matrices in tissue engineering, the availability of native collagen should be investigated by refining the collagen extraction procedure.

O uso de membrana de colágeno de pericárdio bovino na regeneração óssea: características e relato de caso

The aim of this article was to describe the use of the bovine pericardium collagen membrane and to present its physical-chemical characteristics through laboratory tests, in addition to a case report proving its clinical performance. Called native collagen membranes from the animal pericardium, this product has ideal characteristics for promoting bone neoformation in grafting procedures for volumetric augmentation. Scanning electron microscopy (SEM) tests showed the organization of collagen fibers, and tensile tests pointed an adequate resistance to the mechanisms of graft stabilization, through sutures, screws or pins. Within the limitations of this article, it was possible to conclude that the bovine pericardium collagen membrane has the appropriate characteristics for use in guided bone regeneration procedures, with efficient handling, stability, and predictability.