A keratin-based microparticle for cell delivery

Abstract

Keratin-based biomaterials represent an attractive opportunity in the fields of wound healing and tissue regeneration, not only for their chemical and physical properties, but also for their ability to act as a delivery system for a variety of payloads. Importantly, keratins are the only natural biomaterial that is not targeted by specific tissue turnover-related enzymes, giving it potential stability advantages and greater control over degradation after implantation. However, in-situ polymerization chemistry in some keratin systems are not compatible with cells, and incorporation within constructs such as hydrogels may lead to hypoxia and cell death. To address these challenges, we envisioned a pre-formed keratin microparticle on which cells could be seeded, while other payloads (e.g. drugs, growth factors or other biologic compounds) could be contained within, although studies investigating the potential partitioning between phases during emulsion polymerization would need to be conducted. This study employs well-established water-in-oil emulsion procedures as well as a suspension culture method to load keratin-based microparticles with bone marrow-derived mesenchymal stem cells. Fabricated microparticles were characterized for size, porosity and surface structure and further analyzed to investigate their ability to form gels upon hydration. The suspension culture technique was validated based on the ability for loaded cells to maintain their viability and express actin and vinculin proteins, which are key indicators of cell attachment and growth. Maintenance of expression of markers associated with cell plasticity was also investigated. As a comparative model, a collagen-coated microparticle (Sigma) of similar size was used. Results showed that an oxidized form of keratin (“keratose” or “KOS”) formed unique microparticle structures of various size that appeared to contain a fibrous sub-structure. Cell adhesion and viability was greater on keratin microparticles compared to collagen-coated microparticles, while marker expression was retained on both.

Clinical Application of Bone Marrow Mesenchymal Stem/Stromal Cells to Repair Skeletal Tissue

“…Hydrogels and scaffolds use a range of natural and synthetic materials and biopolymers to achieve bone regeneration [ 56 , 57 ]. Natural materials include proteins, such as collagen, gelatin, laminin, keratin, elastin, fibroin, fibrin, heparin; or polysaccharides such as hyaluronan, chitosan and alginate, while those with microbial activity including cellulose, gellan gum and dextran [ 58 , 59 , 60 , 61 , 62 , 63 ]. Synthetic biopolymers include poly(ethylene glycol) (PEG), polyacrylamide (PAM), plyvinyl alcohol (PVA), poly lactic acid to name a few [ 57 , 58 , 64 , 65 ].…”

“…The natural and synthetic materials are fabricated into a range of structures including but not limited to injectable hydrogels, microbeads, nanogels, hydrogel fibers, biofilms, membranes, solid porous scaffolds or sponges. These scaffolds are prepared by microfluidics, in situ polymerization, electrostatic droplet extrusion, emulsification and coaxial air jetting, physical and chemical crosslinking, electrospinning, solvent casting and particulate leaching, gas-foaming, powder compaction, emulsion freeze-drying, thermal phase separation, laser sintering, stereolitography, and 3D printing [ 56 , 59 , 60 ].…”

Self‐Assembly of Platelet Lysates Proteins into Microparticles by Unnatural Disulfide Bonds for Bottom‐Up Tissue Engineering

“…[6] Nevertheless, the most sophisticated designs with high porosity, [7] surface/volume ratio, [8] anisotropic properties, [9] or DOI: 10.1002/adma.202304659 surface topography [10] are often created with synthetic polymers or biologically derived polysaccharides. Protein-based microparticles cover a small niche, with most advanced research focusing on collagen, [11] keratin, [12] elastin-like polypeptides (ELPs), [13] and the well-known gelatin. [14] Proteins are considered emerging biomaterials for biotechnology and bioengineering, boosting cell-material interactions and cell-cell communications.…”

Silver Nanoparticle-Anchored Human Hair Kerateine/PEO/PVA Nanofibers for Antibacterial Application and Cell Proliferation

“…Additionally, keratins contain cell adhesion motifs similar in structure to extracellular matrix proteins (such as collagen or fibronectin), arginine-glycine-aspartate (RGD) and leucine-aspartate-valine (LDV), which can support cell attachment and proliferation [ 5 ]. These unique structures and biological properties make keratin the focus of the biomedical field, including wound dressing, tissue engineering and drug delivery [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Nevertheless, the shortcomings of brittleness, poor mechanical properties and processing properties limit the practical use of keratin [ 13 , 14 ].…”