Porcine collagen type I is now a mainstream material for the fabrication of bioactive biomatrixes in tissue engineering and regenerative medicine. Collagen is the protein with the highest concentration in the ECM and, more specifically, collagen type I occurs in all of the body's skeletal tissues, from skin and bone to tendons and ligaments. This structural protein is responsible for the mechanical rigidity and flexibility of tissues, which makes it a perfect candidate for biomedical use. Porcine type I collagen is widely used because it is emulsified from human collagen, is biologically stable and is an economical, natural resource. Particularly desirable collagen matrices from porcine sources are biocompatible, biodegradable, and provide the biochemical stimuli to enable tissue repair.
Figure 1. Porcine type I collagen mixed with porcine bone graft at a weight ratio of 30:70. (Salamanca E, et al.; 2020)
This replication of the structure and function of natural extracellular matrix is one of its greatest strengths in porcine collagen type I. The ECM provides the attachment, growth and differentiation of cells in the body and is the dynamic environment in which cells thrive and function. When it comes to tissue engineering, this nature can be mimicked to generate working tissues or organs. Porcine collagen type I works best for this, since it is analogous in amino acid sequences and structure to human collagen so it can replicate cellular processes similarly to the native ECM. Its three-helix, fibrous form gives it mechanical stiffness and elasticity, and it is the perfect material to engineer tissues that demand toughness and suppleness, including skin, cartilage and bone. Porcine collagen type I also has great biological features besides its structural benefits that make it useful in biomatrixes. These are among its capacities for cell adhesion and migration, two hallmarks of tissue regeneration. Used as scaffold, collagen type I has receptors for integrins and other receptors on the surface of cells that help them bind to it. This attachment is the final step in the development of cells and new tissue. Also, porcine collagen type I appears to promote the differentiation of cells (including stem cells) into the specialised tissues that will heal them. Collagen type I, for instance, is mainly applied in cartilage repair, bone regeneration, and wound healing of skin where differentiation of cells is crucial to normal tissue function. A third key property of porcine collagen type I is its processing and modification potential. That collagen can be made to gel, sponge, film, scaffold, and fiber, according to the application. This versatility means scientists can modify the material properties to make biomatrixes with the right mechanical, porosity and biodegradability. Collagen sponges and hydrogels, for instance, are used frequently in wound-healing applications, where the material's permeability and wetness are vital. Conversely, in bone tissue engineering, collagen scaffolds can be crosslinked for mechanical strength, to stand up to forces placed on the reconstructed bone. Crosslinking agents like glutaraldehyde or carbodiimides can also be added to make the collagen matrix stronger, less susceptible to enzymatic degradation and still biocompatible.
Because pork collagen type I is bioreformable, its biomedical value goes beyond the bone. Chemical additions, like adding bioactive molecules, can make the material perform better by stimulating specific cellular reactions. For instance, collagen scaffolds could be customised with growth factors, peptides or other bioactive molecules that activate cell proliferation, angiogenesis or collagen production. The familiar example is adding platelet-derived growth factor (PDGF) or transforming growth factor-beta (TGF) to collagen matrix in wound-healing applications because these growth factors are useful for tissue repair by promoting cell migration and matrix remodelling. Further, bioactive peptides such as the RGD (Arg-Gly-Asp) sequence can improve the cell's grip on the collagen scaffold and make the biomaterial even more efficient. Using porcine collagen type I to engineer them into hybrid complexes is another area of emerging promise. It is now becoming increasingly possible to blend collagen with other natural or synthetic biomaterials to make biomatrixes even more versatile. Collanectin, for example, can be conjugated with polysaccharides such as hyaluronic acid or chondroitin sulphate to make composites that are more hydrating, more cell-binding, or more mechanically strong. Sometimes, collagen biomatrixes are added with synthetic polymers, like polylactic acid (PLA) or poly(lactic-co-glycolic acid) (PLGA), to increase the mechanical strength and degradation rates. Such hybrid systems are particularly useful to build scaffolds for applications that need more dense tissues like skin regeneration, which involves a mix of stretch, rigidity and elasticity. It is also possible to bring the potential of porcine collagen type I to use in functional biomaterials like 3D bioprinting and tissue engineering. Bioprinting with collagen bioinks deposited in high-resolution, patient-specific tissue models is now made possible thanks to newer bioprinting techniques that allow for the very precise printing of tissues. Porcine collagen can also be printed in combination with other cells, growth factors and extracellular matrix proteins for 3D bioprinting to create tissue architecture that imitates natural tissue architecture. These printed scaffolds could then be seeded with patient-derived cells to generate tissues for regenerative therapies. The future application of this technology might be developing skin substitutes for burn victims or chronic wound patients. Printing collagen matrixes so they look similar to layers of dermis and epidermis could enable researchers to develop skin substitutes that are more likely to be absorbed into the patient's own tissue and heal more efficiently. What's more, the immunological profile of porcine collagen type I makes it extremely promising for use in human therapeutics. Collagen comes from animals but porcine collagen type I is not very immunogenic, if processed properly. With purification and crosslinking, immunity can be minimised, making it a less dangerous material for human implant. Researchers have discovered that porcine collagen in general does not generate high-level immune reactions unless it's processed in purified, crosslinked form. This is especially useful for applications where it must be implanted for a very long period of time, such as tissue-engineered implants or drug delivery systems. Porcine collagen type I is less immunogenic than other animal collagens, and so its safety profile for human applications is improved. Apart from tissue engineering, porcine collagen type I has also been used for drug delivery, specifically in controlled-release products. matrices of collagen that could be used as carriers for therapeutic substances so that they could be delivered time-delayously. For instance, collagen hydrogels can be filled with growth factors or anti-inflammatory medications to heal chronic wounds or regenerate tissue. The controlled release of these therapeutic molecules from collagen matrix means they stay at the injury site so frequent dosing becomes unnecessary and patients are able to adhere.
Alternate Names:
Type I Collagen (Porcine)
Porcine Collagen
Pig Collagen
Porcine Collagen Hydrogel
Porcine Type I Collagen
Porcine Collagen Fibers
Collagen I (Porcine)
Collagen Type I (Pig)
Porcine Collagen Matrix
Pig Type I Collagen
References:
1. Salamanca E, et al.; Porcine Collagen-Bone Composite Induced Osteoblast Differentiation and Bone Regeneration In Vitro and In Vivo. Polymers (Basel). 2020, 12(1):93
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